%0 journal article %@ 1879-0003 %A Blanco, F.G., Machatschek, R., Keller, M., Hernández-Arriaga, A.M., Godoy, M.S., Tarazona, N.A., Prieto, M.A. %D 2023 %J International Journal of Biological Macromolecules %N Part 2 %P 126760 %R doi:10.1016/j.ijbiomac.2023.126760 %T Nature-inspired material binding peptides with versatile polyester affinities and binding strengths %U https://doi.org/10.1016/j.ijbiomac.2023.126760 Part 2 %X Biodegradable polyesters, such as polyhydroxyalkanoates (PHAs), are having a tremendous impact on biomedicine. However, these polymers lack functional moieties to impart functions like targeted delivery of molecules. Inspired by native GAPs, such as phasins and their polymer-binding and surfactant properties, we generated small material binding peptides (MBPs) for polyester surface functionalization using a rational approach based on amphiphilicity. Here, two peptides of 48 amino acids derived from phasins PhaF and PhaI from Pseudomonas putida, MinP and the novel-designed MinI, were assessed for their binding towards two types of PHAs, PHB and PHOH. In vivo, fluorescence studies revealed selective binding towards PHOH, whilst in vitro binding experiments using the Langmuir-Blodgett technique coupled to ellipsometry showed KD in the range of nM for all polymers and MBPs. Marked morphological changes of the polymer surface upon peptide adsorption were shown by BAM and AFM for PHOH. Moreover, both MBPs were successfully used to immobilize cargo proteins on the polymer surfaces. Altogether, this work shows that by redesigning the amphiphilicity of phasins, a high affinity but lower specificity to polyesters can be achieved in vitro. Furthermore, the MBPs demonstrated binding to PET, showing potential to bind cargo molecules also to synthetic polyesters. %0 dataset %@ %A Sahabudeen, H., Zhang, Q., Liu, Y., Heuchel, M., Machatschek, R. %D 2023 %J Zenodo %R doi:10.5281/zenodo.7782736 %T Mechanistic insights into the deformation and degradation of a 2D metal organic framework %U https://doi.org/10.5281/zenodo.7782736 %X 2D metal-organic frameworks (2D-MOFs) materials can be subjected to various modes of mechanical stresses and strains in a wide range of applications, for which their mechanical properties are critical to reach practical implementations. Despite the rapid developments focused on the preparation of ultrathin 2D-MOF materials, very little is known about their mechanical and degradation behavior. Here, we use the established 2D-MOF PdTCPP-Cu (NAFS-13) as model system, to introduce the Langmuir–Blodgett (LB) technique, combined with interfacial rheology, as a novel in situ method for direct determination of the in-plane Young’s modulus by simultaneously measuring the 2D shear and compression moduli of a 2D-MOF formed at the air-water interface. Furthermore, it can be used to evaluate mechanistic models describing the degradation kinetics of 2D MOFs. To provide a deeper understanding of the factors that determine the Young’s modulus observed in such a set up, we carried out nanoindentation measurements and molecular dynamics (MD) simulations based on classical force fields. This protocol allows us to gain mechanistic insights into the impact of structural defects, temperature, tensile and compression stress on the Young’s modulus of 2D MOFs. %0 conference poster %@ %A Zhang, S., Ma, N., Machatschek, R. %D 2023 %J Makromolekulares Kolloquium Freiburg 2023 %T Fabrication and analysis of laminin-111 Langmuir-Blodgett films with biophysical gradients for screening cellular adhesion %U %X %0 journal article %@ 1616-301X %A Bhuvanesh, T., Nie, Y., Machatschek, R., Ma, N., Lendlein, A. %D 2023 %J Advanced Functional Materials %N 46 %P 2304268 %R doi:10.1002/adfm.202304268 %T Laminin - dynamic bonds enable multifunctionality in a biological 2D network %U https://doi.org/10.1002/adfm.202304268 46 %X A layer of laminins, assembled on a thin sheet of collagen type IV (Col-IV) forms the backbone of the basal lamina, which controls biological processes such as embryogenesis, tissue homeostasis, and development. Here, the dynamic functions of laminin-111 (Lam-111) in ultrathin films at the air–water interface are investigated. It is shown that the 2D confinement induces polymerization and that expansion via adlayer formation occurs only with extended growth time. The highly robust self-assembly enables the functionalization of surfaces with cross-linked 2D Lam-111 networks of defined thickness using little more than a beaker. The 2D laminin material also displays two dynamic functions required for the maintenance of tissues – the capability for self-renewal and self-healing. By assembling Lam-111 2D networks at the surface of Col-IV sheets, freestanding bilayers closely mimicking the basal lamina can be produced in vitro. There is a marked difference in miPSC spreading and adhesion force between Lam-111 sheets assembled in the presence or absence of Col-IV. These fundamental studies highlight the importance of dynamic functions, encoded into the molecular structure of the building blocks, for the assembly, maintenance, and functioning of the complex material systems found in natural tissues and can provide cues for the molecular design of resilient technical systems. %0 journal article %@ 2397-7132 %A Sahabudeen, H., Zhang, Q., Liu, Y., Heuchel, M., Machatschek, R. %D 2023 %J npj 2D Materials and Applications %P 25 %R doi:10.1038/s41699-023-00391-3 %T Mechanistic insights into the deformation and degradation of a 2D metal organic framework %U https://doi.org/10.1038/s41699-023-00391-3 %X 2D metal-organic frameworks (2D-MOFs) materials can be subjected to various modes of mechanical stresses and strains in a wide range of applications, for which their mechanical properties are critical to reach practical implementations. Despite the rapid developments focused on the preparation of ultrathin 2D-MOF materials, very little is known about their mechanical and degradation behavior. Here, we use the established 2D-MOF PdTCPP-Cu (NAFS-13) as model system, to introduce the Langmuir–Blodgett (LB) technique, combined with interfacial rheology, as a novel in situ method for direct determination of the in-plane Young’s modulus by simultaneously measuring the 2D shear and compression moduli of a 2D-MOF formed at the air-water interface. Furthermore, it can be used to evaluate mechanistic models describing the degradation kinetics of 2D MOFs. To provide a deeper understanding of the factors that determine the Young’s modulus observed in such a set up, we carried out nanoindentation measurements and molecular dynamics (MD) simulations based on classical force fields. This protocol allows us to gain mechanistic insights into the impact of structural defects, temperature, tensile and compression stress on the Young’s modulus of 2D MOFs. %0 journal article %@ 0021-9797 %A Saretia, S., Folikumah, M., Liu, Y., Machatschek, R. %D 2023 %J Journal of Colloid and Interface Science %P 176-183 %R doi:10.1016/j.jcis.2022.12.161 %T Understanding the (dis)-assembly of in situ forming hydrogel coatings in a 2D model system %U https://doi.org/10.1016/j.jcis.2022.12.161 %X Non-cross-linked PEG or PEG incubated with cross-linkers at slightly acidic pH desorbs from the interface over time. Cross-linking of PEG at alkaline pH renders 2D hydrogel networks (thickness <1 nm) that are stable against desorption. They are easily transferrable onto solid mica surfaces, forming homogenous coatings as revealed by AFM. The type of dithiol cross-linker used to form the branching centers influences the degradability of these 2D hydrogel networks in the presence of lipase, peroxides, or bases. For example, enzymatic degradation of the 2D hydrogel networks can be switched “on” or “off” depending on the cleavable sites in the cross-linkers. %0 conference poster %@ %A Saretia, S., Machatschek, R. %D 2022 %J MRS Spring Meting 2022 %T Correlating PEG-depsipeptide cross-linking and degradation kinetics using ultrathin hydrogel networks at the air-water interface %U %X %0 journal article %@ 0884-2914 %A Machatschek, R., Heuchel, M., Lendlein, A. %D 2022 %J Journal of Materials Research %N 1 %P 67-76 %R doi:10.1557/s43578-021-00339-7 %T Thin-layer studies on surface functionalization of polyetherimide: Hydrolysis versus amidation %U https://doi.org/10.1557/s43578-021-00339-7 1 %X Among the high-performance and engineering polymers, polyimides and the closely related polyetherimide (PEI) stand out by their capability to react with nucleophiles under relatively mild conditions. By targeting the phthalimide groups in the chain backbone, post-functionalization offers a pathway to adjust surface properties such as hydrophilicity, solvent resistance, and porosity. Here, we use ultrathin PEI films on a Langmuir trough as a model system to investigate the surface functionalization with ethylene diamine and tetrakis(4-aminophenyl)porphyrin as multivalent nucleophiles. By means of AFM, Raman spectroscopy, and interfacial rheology, we show that hydrolysis enhances the chemical and mechanical stability of ultrathin films and allows for the formation of EDC/NHS-activated esters. Direct amidation of PEI was achieved in the presence of a Lewis acid catalyst, resulting in free amine groups rather than cross-linking. When comparing amidation with hydrolysis, we find a greater influence of the latter on material properties. %0 journal article %@ 2329-2237 %A Tarazona, N., Machatschek, R., Balcucho, J., Castro-Mayorga, J., Saldarriaga, J., Lendlein, A. %D 2022 %J MRS Energy & Sustainability %P 28-34 %R doi:10.1557/s43581-021-00015-7 %T Opportunities and challenges for integrating the development of sustainable polymer materials within an international circular (bio)economy concept %U https://doi.org/10.1557/s43581-021-00015-7 %X Leading-edge polymer-based materials for consumer and advanced applications are necessary to achieve sustainable development at a global scale. It is essential to understand how sustainability can be incorporated in these materials via green chemistry, the integration of bio-based building blocks from biorefineries, circular bioeconomy strategies, and combined smart and functional capabilities. %0 journal article %@ 2059-8521 %A Zhang, S., Liu, Y., Machatschek, R., Lendlein, A. %D 2022 %J MRS Advances %N 4 %P 56-62 %R doi:10.1557/s43580-021-00160-8 %T Ultrathin collagen type I films formed at the air-water interface %U https://doi.org/10.1557/s43580-021-00160-8 4 %X Collagen-based biomaterials with oriented fibrils have shown great application potential in medicine. However, it is still challenging to control the type I collagen fibrillogenesis in ultrathin films. Here, we report an approach to produce cohesive and well-organized type I collagen ultrathin films of about 10 nm thickness using the Langmuir-Blodgett technique. Ellipsometry, rheology, and Brewster angle microscopy are applied to investigate in situ how the molecules behave at the air-water interface, both at room temperature and 37 °C. The interfacial storage modulus observed at room temperature vanishes upon heating, indicating the existence and disappearance of the network structure in the protein nanosheet. The films were spanning over holes as large as 1 mm diameter when transferred at room temperature, proving the strong cohesive interactions. A highly aligned and fibrillar structure was observed by atomic force microscopy (AFM) and optical microscopy. %0 journal article %@ 0884-2914 %A Hoffmann, F., Machatschek, R., Lendlein, A. %D 2022 %J Journal of Materials Research %P 1093-1101 %R doi:10.1557/s43578-022-00495-4 %T Analytical model and Monte Carlo simulations of polymer degradation with improved chain cut statistics %U https://doi.org/10.1557/s43578-022-00495-4 %X The degradation of polymers is described by mathematical models based on bond cleavage statistics including the decreasing probability of chain cuts with decreasing average chain length. We derive equations for the degradation of chains under a random chain cut and a chain end cut mechanism, which are compared to existing models. The results are used to predict the influence of internal molecular parameters. It is shown that both chain cut mechanisms lead to a similar shape of the mass or molecular mass loss curve. A characteristic time is derived, which can be used to extract the maximum length of soluble fragments l of the polymer. We show that the complete description is needed to extract the degradation rate constant k from the molecular mass loss curve and that l can be used to design polymers that lose less mechanical stability before entering the mass loss phase. %0 conference lecture %@ %A Tarazona, N., Machatschek, R., Lendlein, A. %D 2022 %J MRS Spring Meeting 2022 %T Decreasing the glass transition temperature (Tg) of poly(ethylene terephthalate) films at the air-water interface by reducing sample dimensions %U %X %0 conference poster %@ %A Machatschek, R., Sahabudeen, H., Lendlein, A. %D 2022 %J MRS Spring Meeting 2022 %T In situ mechanical characterization and degradation of 2D MOFs %U %X %0 journal article %@ 0009-3084 %A Sęk, A., Perczyk, P., Szcześ, A., Machatschek, R., Wydro, P. %D 2022 %J Chemistry and Physics of Lipids %P 105236 %R doi:10.1016/j.chemphyslip.2022.105236 %T Studies on the interactions of tiny amounts of common ionic surfactants with unsaturated phosphocholine lipid model membranes %U https://doi.org/10.1016/j.chemphyslip.2022.105236 %X In order to provide the fundamental information about the interactions of common anionic surfactants with the basic unsaturated phospholipids the influence of three cationic (dodecyltrimethylammonium bromide, DTAB; tetradecyltrimethylammonium bromide, TTAB and hexadecyltrimethylamonium bromide, CTAB) and one anionic (sodium dodecylsulfate, SDS) surfactants on the properties of the 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) layers was investigated. The studies proved that a tiny amount of the ionic surfactant added to the already synthesized liposome suspension is sufficient to change the zeta potential of the POPC and DOPC liposomes significantly. This impact increases with the surfactant concentration, the alkyl chain length of the surfactant and the degree of lipid saturation. Moreover, this effect is greater for the anionic surfactant than for the cationic one of the same alkyl chain length. The observed findings were confirmed in the course of the research carried out with the use of the corresponding Langmuir monolayers where the surface pressure – mean area isotherms, the compressibility modulus – surface pressure dependences, the monolayer penetration tests, the surface potential – mean molecular area isotherms and Brewster angle microscopy were discussed. It was found that the presence of the surfactants shifts the isotherms towards larger molecular area, to the higher extent for the SDS than DTAB. This effect increases with the increasing surfactant concentration in the subphase. Moreover, the investigated surfactants remain in the monolayer even at high surface pressure. Nevertheless, no effect on the morphology of the POPC and DOPC monolayers was detected from the BAM images. The surface potential and surface charge of the liposomes calculated on the basis of the zeta potential results reflected the interactions between the surfactant and the lipid layers. %0 journal article %@ 2667-1093 %A Tarazona, N., Wei, R., Brott, S., Pfaff, L., Bornscheuer, U., Lendlein, A., Machatschek, R. %D 2022 %J Chem Catalysis %N 12 %P 3573-3589 %R doi:10.1016/j.checat.2022.11.004 %T Rapid depolymerization of poly(ethylene terephthalate) thin films by a dual-enzyme system and its impact on material properties %U https://doi.org/10.1016/j.checat.2022.11.004 12 %X Enzymatic hydrolysis holds great promise for plastic waste recycling and upcycling. The interfacial catalysis mode, and the variability of polymer specimen properties under different degradation conditions, add to the complexity and difficulty of understanding polymer cleavage and engineering better biocatalysts. We present a systemic approach to studying the enzyme-catalyzed surface erosion of poly(ethylene terephthalate) (PET) while monitoring/controlling operating conditions in real time with simultaneous detection of mass loss and changes in viscoelastic behavior. PET nanofilms placed on water showed a porous morphology and a thickness-dependent glass transition temperature (Tg) between 40°C and 44°C, which is >20°C lower than the Tg of bulk amorphous PET. Hydrolysis by a dual-enzyme system containing thermostabilized variants of Ideonella sakaiensis PETase and MHETase resulted in a maximum depolymerization of 70% in 1 h at 50°C. We demonstrate that increased accessible surface area, amorphization, and Tg reduction speed up PET degradation while simultaneously lowering the threshold for degradation-induced crystallization. %0 conference poster %@ %A Zhang, S., Ma, N., Machatschek, R. %D 2022 %J 17th European Conference on Organized Films (ECOF17) %T Fabrication and quantitative analysis of laminin111 Langmuir-Blodgett film with biophysical gradients %U %X %0 conference lecture %@ %A Tarazona, N.A., Wie, R., Bornscheuer, U.T., Machatschek, R. %D 2022 %J 10th International Congress on Biocatalysis (biocat2022) %T Accelerated enzymatic degradation of poly(ethylene terephthalate) in a thickness-dependent manner %U %X %0 conference lecture %@ %A Saretia, S., Machatschek, R., Lendlein, A. %D 2021 %J 2021 Virtual MRS Spring Meeting %T Degradation kinetics of oligo(ε-caprolactone) ultrathin films: Influence of crystallinity %U %X %0 journal article %@ 2196-7350 %A Machatschek, R., Saretia, S., Lendlein, A. %D 2021 %J Advanced Materials Interfaces %N 6 %P 2001926 %R doi:10.1002/admi.202001926 %T Assessing the Influence of Temperature‐Memory Creation on the Degradation of Copolyesterurethanes in Ultrathin Films %U https://doi.org/10.1002/admi.202001926 6 %X Copolyesterurethanes (PDLCLs) based on oligo(ε‐caprolactone) (OCL) and oligo(ω‐pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature‐memory polymers. The temperature‐memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt% OPDL content are carried out under enzymatic catalysis. The temperature‐memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization‐modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X‐ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation. %0 journal article %@ 2196-7350 %A Saretia, S., Machatschek, R., Bhuvanesh, T., Lendlein, A. %D 2021 %J Advanced Materials Interfaces %N 7 %P 2001940 %R doi:10.1002/admi.202001940 %T Effect of Water on Crystallization and Melting of Telechelic Oligo(ε‐caprolactone)s in Ultrathin Films %U https://doi.org/10.1002/admi.202001940 7 %X The thermal behavior of ultrathin, semi‐crystalline films of oligo(ε‐caprolactone)s (OCLs) with hydroxy or methacrylate end groups, is studied by the Langmuir technique in dependence on mean molecular areas and crystallization temperatures. The films on solid substrate as obtained by Langmuir–Schaefer transfer exhibit different lamellar thicknesses, crystal number densities, and lateral sizes. The melting temperature of OCL single crystals at the water and solid surface is proportional to the inverse crystal thickness and generally lower than in bulk PCL. An influence of OCL end groups on the melting behavior is observed mainly at the air–solid interface, where methacrylate end capped OCL melts at lower temperatures than hydroxy end capped OCL. Comparing the underlying substrate, melting/recrystallization of OCL ultrathin films is achievable at lower temperatures at the air–water interface than at the air–solid interface, where recrystallization is not identifiable. Recrystallization at the air–water interface generally occurs at higher temperature than the initial crystallization temperature. The surface pressure, as an additional thermodynamic variable, seems to further affect the crystallization behavior, with crystal thickness and lateral growth rate increasing with surface pressure. The results presented here are important when designing temperature‐sensitive or active nanostructured materials or interfaces based on OCL. %0 journal article %@ 2059-8521 %A Saretia, S., Machatschek, R., Lendlein, A. %D 2021 %J MRS Advances %N 10 %P 283-290 %R doi:10.1557/s43580-021-00020-5 %T Highly crystalline PCL ultrathin films as thermally switchable biomaterial coatings %U https://doi.org/10.1557/s43580-021-00020-5 10 %X Semi-crystalline oligomers are explored as functionalized thermoswitchable coatings for modification of biomaterials surface. Highly crystalline oligo(ε-caprolactone) (OCL) films are prepared at the air–water interface by the Langmuir technique, which consist of tightly packed single crystals. Their morphology and melting temperature can be tuned by the chemical structure of the OCL end-groups (hydroxy or methacrylate) and by the crystallization temperature (12 or 21 °C) as physical parameter. This demand of high crystallite density and adjustable morphology of coatings is not met by conventional methodologies for preparing thin films, e.g., spin coating, spray coating, or solvent evaporation. The high crystallinity reduces the enzymatic degradation rate of the films on both water and solid surfaces. The high density of methacrylate end-groups at the crystal surfaces enables post-functionalization, which was demonstrated using fluorescein dimethacrylate as chemically linked label. The thermoswitching behavior (melting and recrystallization) of fluorescein functionalized, highly crystalline OCL films shows temperature-dependent distribution of the chemically linked fluorescein moieties, which are accumulated on the surfaces of crystals, and homogeneously dispersed when the crystals are molten. Thermally switchable highly crystalline films are relevant for cell substrates modulating adhesion at the biointerface or for coatings as barrier layer influencing the degradation rate. %0 conference lecture %@ %A Hoffmann, F., Machatschek, R., Lendlein, A. %D 2021 %J 2021 Virtual MRS Spring Meeting %T Predicting polymer degradation by combining Monte Carlo Simulations and analytical models %U %X %0 conference lecture %@ %A Tarazona, N., Machatschek, R., Castro-Mayorga, J., Salcedo-Galán, F., Lendlein, A. %D 2021 %J 2021 Virtual MRS Spring Meeting %T Plastics in view of sustainability – an international initiative towards education and training of young scientists %U %X %0 conference poster %@ %A Sahabudeen, H., Machatschek, R., Liu, Y., Lendlein, A. %D 2021 %J Advanced Functional Polymers for Medicine (AFPM) %T Non-destructive mechanical testing of freestanding 2D MOF by interfacial rheology %U %X %0 conference lecture %@ %A Machatschek, R., Heuchel, M., Lendlein, A. %D 2021 %J Virtual MRS Spring Meeting %T Cross-linking of polyetherimide by bi- and tetrafunctional nucleophiles in ultrathin layers %U %X %0 journal article %@ 2059-8521 %A Saretia, S., Machatschek, R., Lendlein, A. %D 2021 %J MRS Advances %N 33 %P 790-795 %R doi:10.1557/s43580-021-00067-4 %T Degradation kinetics of oligo(ε-caprolactone) ultrathin films: Influence of crystallinity %U https://doi.org/10.1557/s43580-021-00067-4 33 %X The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(ε-caprolactone) (OCL) are prepared at the air–water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH ~ 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices. %0 journal article %@ 0884-2914 %A Machatschek, R., Heuchel, M., Lendlein, A. %D 2021 %J Journal of Materials Research %N 14 %P 2987-2994 %R doi:10.1557/s43578-021-00267-6 %T Hydrolytic stability of polyetherimide investigated in ultrathin films %U https://doi.org/10.1557/s43578-021-00267-6 14 %X Increasing the surface hydrophilicity of polyetherimide (PEI) through partial hydrolysis of the imide groups while maintaining the length of the main-chain was explored for adjusting its function in biomedical and membrane applications. The outcome of the polymer analogous reaction, i.e., the degree of ring opening and chain cleavage, is difficult to address in bulk and microstructured systems, as these changes only occur at the interface. Here, the reaction was studied at the air–water interface using the Langmuir technique, assisted by atomic force microscopy and vibrational spectroscopy. Slow PEI hydrolysis sets in at pH > 12. At pH = 14, the ring opening is nearly instantaneous. Reduction of the layer viscosity with time at pH = 14 suggested moderate chain cleavage. No hydrolysis was observed at pH = 1. Hydrolyzed PEI films had a much more cohesive structure, suggesting that the nanoporous morphology of PEI can be tuned via hydrolysis. %0 journal article %@ 2399-7532 %A Sahabudeen, H., Machatschek, R., Lendlein, A. %D 2021 %J Multifunctional Materials %N 4 %P 042001 %R doi:10.1088/2399-7532/ac1e7d %T Multifunctionality as design principle for contact lens materials %U https://doi.org/10.1088/2399-7532/ac1e7d 4 %X From synthesis through storage to disposal, contact lenses (CLs) interact with different system environments throughout their functional life cycle. To fulfill their therapeutic purpose, they need to exhibit a distinct behavior in each of them, which is achieved through a combination of different material functions. As such, CL materials are a showcase of highly advanced and mass-produced multifunctional biomaterials. Their great relevance and long history mean that a vast amount of work has gone into the implementation of ever more advanced functions. From understanding the approaches used to achieve multifunctionality in CLs, a lot of inspiration for the design of other multifunctional medical devices can be drawn. Therefore, here, we provide a systematic overview of the different functions that are combined in today's CL materials, together with their quantification methods, chemical design principles and fabrication techniques. We further provide an outlook on the functions that are currently under investigation for the next generation of commercial CLs. %0 journal article %@ 2159-6859 %A Izraylit, V., Liu, Y., Tarazona, N., Machatschek, R., Lendlein, A. %D 2021 %J MRS Communications %N 6 %P 850-855 %R doi:10.1557/s43579-021-00107-y %T Crystallization and degradation behaviour of multiblock copolyester blends in Langmuir monolayers %U https://doi.org/10.1557/s43579-021-00107-y 6 %X Supporting the wound healing of soft tissues requires fixation devices becoming more elastic while degrading. To address this unmet need, we designed a blend of degradable multiblock copolymers, which is cross-linked by PLA stereocomplexation combining two soft segments differing substantially in their hydrolytic degradation rate. The degradation path and concomitant structural changes are predicted by Langmuir monolayer technique. The fast hydrolysis of one soft segment leads to a decrease of the total polymer mass at constant physical cross-linking density. The corresponding increase of the average spacing between the network nodes suggests the targeted increase of the blend’s flexibility. %0 conference poster %@ %A Machatschek, R., Saretia, S., Lendlein, A. %D 2021 %J MRS Fall Meeting 2021 %T Degradation of 2D Materials Formed by Crosslinking of Hydrophilic Macromolecules %U %X %0 journal article %@ 2196-7350 %A Tarazona, N., Machatschek, R., Lendlein, A. %D 2020 %J Advanced Materials Interfaces %N 17 %P 2000872 %R doi:10.1002/admi.202000872 %T Influence of Depolymerases and Lipases on the Degradation of Polyhydroxyalkanoates Determined in Langmuir Degradation Studies %U https://doi.org/10.1002/admi.202000872 17 %X Microbially produced polyhydroxyalkanoates (PHAs) are polyesters that are degradable by naturally occurring enzymes. Albeit PHAs degrade slowly when implanted in animal models, their disintegration is faster compared to abiotic hydrolysis under simulated physiological environments. Ultrathin Langmuir‐Blodgett (LB) films are used as models for fast in vitro degradation testing, to predict enzymatically catalyzed hydrolysis of PHAs in vivo. The activity of mammalian enzymes secreted by pancreas and liver, potentially involved in biomaterials degradation, along with microbial hydrolases is tested toward LB‐films of two model PHAs, poly(3‐R‐hydroxybutyrate) (PHB) and poly[(3‐R‐hydroxyoctanoate)‐co‐(3‐R‐hydroxyhexanoate)] (PHOHHx). A specific PHA depolymerase from Streptomyces exfoliatus, used as a positive control, is shown to hydrolyze LB‐films of both polymers regardless of their side‐chain‐length and phase morphology. From amorphous PHB and PHOHHx, ≈80% is eroded in few hours, while mass loss for semicrystalline PHB is 25%. Surface potential and interfacial rheology measurements show that material dissolution is consistent with a random‐chain‐scission mechanism. Degradation‐induced crystallization of semicrystalline PHB LB‐films is also observed. Meanwhile, the surface and the mechanical properties of both LB‐films remain intact throughout the experiments with lipases and other microbial hydrolases, suggesting that non‐enzymatic hydrolysis could be the predominant factor for acceleration of PHAs degradation in vivo. %0 journal article %@ 2059-8521 %A Bhuvanesh, T., Machatschek, R., Liu, Y., Ma, N., Lendlein, A. %D 2020 %J MRS Advances %N 12 - 13 %P 609-620 %R doi:10.1557/adv.2019.401 %T Self-stabilized fibronectin films at the air/water interface %U https://doi.org/10.1557/adv.2019.401 12 - 13 %X Fibronectin (FN) is a mediator molecule, which can connect cell receptors to the extracellular matrix (ECM) in tissues. This function is highly desirable for biomaterial surfaces in order to support cell adhesion. Controlling the fibronectin adsorption profile on substrates is challenging because of possible conformational changes after deposition, or due to displacement by secondary proteins from the culture medium. Here, we aim to develop a method to realize self-stabilized ECM glycoprotein layers with preserved native secondary structure on substrates. Our concept is the assembly of FN layers at the air-water (A-W) interface by spreading FN solution as droplets on the interface and transfer of the layer by the Langmuir-Schäfer (LS) method onto a substrate. It is hypothesized that 2D confinement and high local concentration at A-W interface supports FN self-interlinking to form cohesive films. Rising surface pressure with time, plateauing at 10.5 mN·m-1 (after 10 hrs), indicated that FN was self-assembling at the A-W interface. In situ polarization-modulation infrared reflection absorption spectroscopy of the layer revealed that FN maintained its native anti-parallel β-sheet structure after adsorption at the A-W interface. FN self-interlinking and elasticity was shown by the increase in elastic modulus and loss modulus with time using interfacial rheology. A network-like structure of FN films formed at the A-W interface was confirmed by atomic force microscopy after LS transfer onto Si-wafer. FN films consisted of native, globular FN molecules self-stabilized by intermolecular interactions at the A-W interface. Therefore, the facile FN self-stabilized network-like films with native anti-parallel β-sheet structure produced here, could serve as stable ECM protein coatings to enhance cell attachment on in vitro cell culture substrates and planar implant materials. %0 journal article %@ 0168-3659 %A Machatschek, R., Lendlein, A. %D 2020 %J Journal of Controlled Release %P 276-284 %R doi:10.1016/j.jconrel.2019.12.044 %T Fundamental insights in PLGA degradation from thin film studies %U https://doi.org/10.1016/j.jconrel.2019.12.044 %X Poly(lactide-co-glycolide)s are commercially available degradable implant materials, which are typically selected based on specifications given by the manufacturer, one of which is their molecular weight. Here, we address the question whether variations in the chain length and their distribution affect the degradation behavior of Poly[(rac-lactide)-co-glycolide]s (PDLLGA). The hydrolysis was studied in ultrathin films at the air-water interface in order to rule out any morphological effects. We found that both for purely hydrolytic degradation as well as under enzymatic catalysis, the molecular weight has very little effect on the overall degradation kinetics of PDLLGAs. The quantitative analysis suggested a random scission mechanism. The monolayer experiments showed that an acidic micro-pH does not accelerate the degradation of PDLLGAs, in contrast to alkaline conditions. The degradation experiments were combined with interfacial rheology measurements, which showed a drastic decrease of the viscosity at little mass loss. The extrapolated molecular weight behaved similar to the viscosity, dropping to a value near to the solubility limit of PDLLGA oligomers before mass loss set in. This observation suggests a solubility controlled degradation of PDLLGA. Conclusively, the molecular weight affects the degradation of PDLLGA devices mostly in indirect ways, e.g. by determining their morphology and porosity during fabrication. Our study demonstrates the relevance of the presented Langmuir degradation method for the design of controlled release systems. %0 journal article %@ 2059-8521 %A Tarazona, N., Machatschek, R., Lendlein, A. %D 2020 %J MRS Advances %N 11 -12 %P 667-677 %R doi:10.1557/adv.2019.458 %T Relation between Surface Area and Surface Potential Change during (co)Polyesters Degradation as Langmuir Monolayer %U https://doi.org/10.1557/adv.2019.458 11 -12 %X Polyhydroxyalkanoates (PHAs) are degradable (co)polyesters synthesized by microorganisms with a variety of side-chains and co-monomer ratios. PHAs can be efficiently hydrolyzed under alkaline conditions and by PHA depolymerase enzymes, altering their physicochemical properties. Using 2D Langmuir monolayers as model system to study the degradation behavior of macromolecules, we aim to describe the the interdependency between the degradation of two PHAs and the surface potential, which influences material-proteins interaction and cell response. We hypothesize that the mechanism of hydrolysis of the labile ester bonds in (co)polyesters defines the evolution of the surface potential, owing to the rate of accumulation of charged insoluble degradation products. The alkaline hydrolysis and the enzymatically catalyzed hydrolysis of PHAs were previously defined as chain-end scission and random-scission mechanisms, respectively. In this study, these two distinct scenarios are used to validate our model. The surface potential change during the chain-end scission of poly(3-R-hydroxybutyrate) (PHB) under alkaline conditions was compared to that of the enzymatically catalyzed hydrolysis (random-scission) of poly[(3-R-hydroxyoctanoate)-co-(3-R-hydroxyhexanoate)] (PHOHHx), using the Langmuir monolayer technique. In the random-scission mechanism the dissolution of degradation products, measured as a decrease in the area per molecule, was preceded by a substantial change of the surface potential, provoked by the negative charge of the broken ester bonds accumulated in the air-water interface. In contrast, when chains degraded via the chain-ends, the surface potential changed in line with the dissolution of the material, presenting a kinetic dependent on the surface area of the monolayers. These results provide a basis for understanding PHAs degradation mechanism. Future research on (co)polymers with different main-chain lengths might extend the elucidation of the surface potential development of (co)polyesters as Langmuir monolayer. %0 journal article %@ 2059-8521 %A Machatschek, R., Saretia, S., Lendlein, A. %D 2020 %J MRS Advances %N 11 - 12 %P 679-691 %R doi:10.1557/adv.2019.457 %T The interplay between network morphology and degradation kinetics of polymers: Theoretical and experimental analysis by means of a 2D model system %U https://doi.org/10.1557/adv.2019.457 11 - 12 %X Network formation by cross-linking is a common method to incorporate functions like elastic deformability, shape-memory capability or hydrogel formation into polymer materials for medical applications. Since these materials are often intended to degrade, their design would benefit from a quantitative prediction of the interdependence between network architecture and degradation behavior. Here, we introduce a quantitative description of the degradation behavior of polymer networks. A simplified model was developed under the assumption of having an ideal network, where all network strands are terminated by network nodes and each node is connected to the same number of strands. To describe the degradation of real networks, the model was modified by allowing for a varying connectivity of network nodes, which also included free chain-ends. The models were validated by comparison with Langmuir monolayer degradation data from 2D networks formed by cross-linking oligo(ε-caprolactone)diols with dialdehydes. We found that both the ideal network hypothesis and the real network model were in excellent agreement with the experimental data, with the ideal network hypothesis requiring longer network strands than the real network to result in the same degradation behavior. The models were further used to calculate the degradation curves of the corresponding, non cross-linked molecules. By comparison, it was found that the network formation increases the time required to reach 50% degradation of oligo(ε-caprolactone)diols by only 20%. This difference mainly arises from attaching free chain ends to network points. %0 journal article %@ 1525-7797 %A Tarazona, N., Machatschek, R., Lendlein, A. %D 2020 %J Biomacromolecules %N 2 %P 761-771 %R doi:10.1021/acs.biomac.9b01458 %T Unraveling the Interplay between Abiotic Hydrolytic Degradation and Crystallization of Bacterial Polyesters Comprising Short and Medium Side-Chain-Length Polyhydroxyalkanoates %U https://doi.org/10.1021/acs.biomac.9b01458 2 %X Polyhydroxyalkanoates (PHAs) have attracted attention as degradable (co)polyesters which can be produced by microorganisms with variations in the side chain. This structural variation influences not only the thermomechanical properties of the material but also its degradation behavior. Here, we used Langmuir monolayers at the air–water (A–W) interface as suitable models for evaluating the abiotic degradation of two PHAs with different side-chain lengths and crystallinity. By controlling the polymer state (semicrystalline, amorphous), the packing density, the pH, and the degradation mechanism, we could draw several significant conclusions. (i) The maximum degree of crystallinity for a PHA film to be efficiently degraded up to pH = 12.3 is 40%. (ii) PHA made of repeating units with shorter side-chain length are more easily hydrolyzed under alkaline conditions. The efficiency of alkaline hydrolysis decreased by about 65% when the polymer was 40% crystalline. (iii) In PHA films with a relatively high initial crystallinity, abiotic degradation initiated a chemi-crystallization phenomenon, detected as an increase in the storage modulus (E′). This could translate into an increase in brittleness and reduction in the material degradability. Finally, we demonstrate the stability of the measurement system for long-term experiments, which allows degradation conditions for polymers that could closely simulate real-time degradation. %0 journal article %@ 2666-3864 %A Machatschek, R., Schulz, B., Lendlein, A. %D 2020 %J Cell reports. Physical science %N 1 %P 100009 %R doi:10.1016/j.xcrp.2019.100009 %T Quantitative Model and Thin Film Studies Relating Molecular Architecture and Degradation of Multifunctional Materials %U https://doi.org/10.1016/j.xcrp.2019.100009 1 %X A characteristic of multifunctional polymer materials is their complex molecular architecture, which creates a challenge in predicting their degradation behavior. Hence, their appropriate design demands a quantitative correlation between their molecular architecture and their molecular degradation behavior. Here, we present a method to analyze and predict the degradation of such molecules by fast and conclusive Langmuir monolayer experiments in combination with kinetic models. Important findings include the retardation of the degradation in the early stage caused by high molecular weight as well as end caps. In multiblock copolymers consisting of fast- and slow-degrading blocks, the molecular weight and the block length have little effect on degradation behavior. In semicrystalline multiblock copolymers, the degradation rate of amorphous blocks is reduced compared to completely amorphous materials. The reaction rate constants that are obtained by this method are essential for predictive models for the degradation of multifunctional devices. %0 conference poster %@ %A Hoffmann, F., Machatschek, R., Barbirz, S., Lendlein, A. %D 2020 %J Virtual MRS Spring/Fall Meeting %T Molecular modeling of biomaterial degradation in two dimensions %U %X %0 conference poster %@ %A Machatschek, R., Lendlein, A. %D 2020 %J Controlled Release Society - CRS 2020 Virtual Annual Meeting %T Monolayer studies as tool to predict the degradation behavior of (co)polyester matrices %U %X %0 journal article %@ 2059-8521 %A Hoffmann, F., Machatschek, R., Lendlein, A. %D 2020 %J MRS Advances %N 52 - 53 %P 2737-2749 %R doi:10.1557/adv.2020.386 %T Understanding the impact of crystal lamellae organization on small molecule diffusion using a Monte Carlo approach %U https://doi.org/10.1557/adv.2020.386 52 - 53 %X Many physicochemical processes depend on the diffusion of small molecules through solid materials. While crystallinity in polymers is advantageous with respect to structure performance, diffusion in such materials is difficult to predict. Here, we investigate the impact of crystal morphology and organization on the diffusion of small molecules using a lattice Monte Carlo approach. Interestingly, diffusion determined with this model does not depend on the internal morphology of the semi-crystalline regions. The obtained insight is highly valuable for developing predictive models for all processes in semi-crystalline polymers involving mass transport, like polymer degradation or drug release, and provide design criteria for the time-dependent functional behavior of multifunctional polymer systems. %0 conference poster %@ %A Saretia, S., Machatschek, R., Lendlein, A. %D 2020 %J 2020 Virtual MRS Spring/Fall Meeting %T Highly crystalline PCL ultrathin films as thermally switchable biomaterial coatings %U %X %0 conference lecture %@ %A Lendlein, A., Tarazona, N., Machatschek, R. %D 2020 %J Controlled Release Society - CRS 2020 Virtual Annual Meeting %T Influence of enzymes on the degradation behavior of polyhydroxyalkanoates determined in Langmuir degradation studies %U %X %0 journal article %@ 1748-605X %A Bhuvanesh, T., Machatschek, R., Lysyakova, L., Kratz, K., Schulz, B., Ma, N., Lendlein, A. %D 2019 %J Biomedical Materials %N 2 %P 024101 %R doi:10.1088/1748-605X/aaf464 %T Collagen type-IV Langmuir and Langmuir-Schaefer layers as model biointerfaces to direct stem cell adhesion %U https://doi.org/10.1088/1748-605X/aaf464 2 %X In biomaterial development, the design of material surfaces that mimic the extra-cellular matrix (ECM) in order to achieve favorable cellular instruction is rather challenging. Collagen-type IV (Col-IV), the major scaffolding component of Basement membranes, a specialized ECM with multiple biological functions, has the propensity to form networks by self-assembly and supports adhesion of cells such as endothelial cells or stem cells. The preparation of biomimetic Col-IV network like layers to direct cell responses is difficult. We hypothesize that the morphology of the layer, and especially the density of the available adhesion sites, regulates the cellular adhesion to the layer. The Langmuir monolayer technique allows for preparation of thin layers with precisely controlled packing density at the air-water (A-W) interface. Transferring these layers onto cell culture substrates using the Langmuir Schäfer (LS) technique should therefore provide a pathway for preparation of BM mimicking layers with controlled cell adherence properties. In situ characterization using ellipsometry and polarization modulation-infrared reflection absorption spectroscopy of Col-IV layer during compression at the A-W interface reveal that there is linear increase of surface molecule concentration with negligible orientational changes up to a surface pressure of 25 mNcenterdotm<sup>-1</sup>. Smooth and homogeneous Col-IV network-like layers are successfully transferred by LS method at 15 mNcenterdotm<sup>-1</sup> onto poly(ethyleneterepthalate) (PET), which is a common substrate for cell culture. In contrast, the organization of Col-IV on PET prepared by the traditionally employed solution deposition method results in rather inhomogeneous layers with the appearance of aggregates and multilayers. Progressive increase in the number of early adherent mesenchymal stem cells (MSCs) after 24 h by controlling the Col-IV density by LS transfer at 10, 15 and 20 mNcenterdotm<sup>-1</sup> on PET is shown. LS method offers the possibility to control protein characteristics on biomaterial surfaces such as molecular density and thereby, modulate cell responses. %0 journal article %@ 2159-6859 %A Machatschek, R., Schoene, A.-C., Raschdorf, E., Ihlenburg, R.B.J., Schulz, B., Lendlein, A. %D 2019 %J MRS Communications %N 1 %P 170-180 %R doi:10.1557/mrc.2019.21 %T Interfacial properties of morpholine-2,5-dione-based oligodepsipeptides and multiblock copolymers %U https://doi.org/10.1557/mrc.2019.21 1 %X Oligodepsipeptides (ODPs) with alternating amide and ester bonds prepared by ring-opening polymerization of morpholine-2,5-dione derivatives are promising matrices for drug delivery systems and building blocks for multifunctional biomaterials. Here, we elucidate the behavior of three telechelic ODPs and one multiblock copolymer containing ODP blocks at the air–water interface. Surprisingly, whereas the oligomers and multiblock copolymers crystallize in bulk, no crystallization is observed at the air–water interface. Furthermore, polarization modulation infrared reflection absorption spectroscopy is used to elucidate hydrogen bonding and secondary structures in ODP monolayers. The results will direct the development of the next ODP-based biomaterial generation with tailored properties for highly sophisticated applications. %0 journal article %@ 1525-7797 %A Tarazona, N.A., Machatschek, R., Schulz, B., Prieto, M.A., Lendlein, A. %D 2019 %J Biomacromolecules %N 9 %P 3242-3252 %R doi:10.1021/acs.biomac.9b00069 %T Molecular Insights into the Physical Adsorption of Amphiphilic Protein PhaF onto Copolyester Surfaces %U https://doi.org/10.1021/acs.biomac.9b00069 9 %X Phasins are amphiphilic proteins located at the polymer–cytoplasm interface of bacterial polyhydroxyalkanoates (PHA). The immobilization of phasins on biomaterial surfaces is a promising way to enhance the hydrophilicity and supply cell-directing elements in bioinstructing processes. Optimizing the physical adsorption of phasins requires deep insights into molecular processes during polymer–protein interactions to preserve their structural conformation while optimizing surface coverage. Here, the assembly, organization, and stability of phasin PhaF from Pseudomonas putida at interfaces is disclosed. The Langmuir technique, combined with in situ microscopy and spectroscopic methods, revealed that PhaF forms stable and robust monolayers at different temperatures, with an almost flat orientation of its α-helix at the air–water interface. PhaF adsorption onto preformed monolayers of poly[(3-R-hydroxyoctanoate)-co-(3-R-hydroxyhexanoate)] (PHOHHx), yields stable mixed layers below π = ∼15.7 mN/m. Further insertion induces a molecular reorganization. PHOHHx with strong surface hydrophobicity is a more adequate substrate for PhaF adsorption than the less hydrophobic poly[(rac-lactide)-co-glycolide] (PLGA). The observed orientation of the main axis of the protein in relation to copolyester interfaces ensures the best exposure of the hydrophobic residues, providing a suitable coating strategy for polymer functionalization. %0 journal article %@ 1748-605X %A Saretia, S., Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J Biomedical Materials %N 3 %P 034103 %R doi:10.1088/1748-605X/ab0cef %T Reversible 2D networks of oligo(Epsilon-caprolactone) at the air–water interface %U https://doi.org/10.1088/1748-605X/ab0cef 3 %X Hydroxyl terminated oligo(ε-caprolactone) (OCL) monolayers were reversibly cross-linked forming two dimensional networks (2D) at the air–water interface. The equilibrium reaction with glyoxal as the cross-linker is pH-sensitive. Pronounced contraction in the area of the prepared 2D OCL films in dependence of surface pressure and time revealed the process of the reaction. Cross-linking inhibited crystallization and retarded enzymatic degradation of the OCL film. Altering the subphase pH led to a cleavage of the covalent acetal cross-links. The reversibility of the covalent acetal cross-links was proved by observing an identical isotherm as non-cross-linked sample. Besides as model systems, these customizable reversible OCL 2D networks are intended for use as pH responsive drug delivery systems or functionalized cell culture substrates. %0 conference lecture %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J MRS Fall Meeting %T Monolayer Studies on the Interplay between Cross-Linking and the Degradation Kinetics of Biomaterials %U %X %0 conference poster %@ %A Tarazona, N., Machatschek, R., Schulz, B., Prieto, M., Lendlein, A. %D 2019 %J 16th European Conference on Organized Films (ECOF 16) %T Understanding the function of polyester-binding proteins: from bacteria to the air-water interface %U %X %0 conference poster %@ %A Vijaya Bhaskar, T., Machatschek, R., Schulz, B., Ma, N., Lendlein, A. %D 2019 %J MRS Fall Meeting 2019 %T Biomimetic Fibronectin Fibrillogenesis at Air/Water interface %U %X %0 conference poster %@ %A Tarazona, N., Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J MRS Fall Meeting 2019 %T Real-time Characterization of the Degradation and Chemi-crystallization Phenomenon in NaturalbasedPolymers at the Air-Water Interface: the Story of Bacterial Polyesters %U %X %0 conference poster %@ %A Saretia, S., Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J Polydays 2019 - Polymer Science and Engineering in View of Digitalization %T Modulating enzymatic degradation of poly(å-caprolactone) monolayer at the air-water interface by two dimensional cross-linking %U %X %0 conference lecture %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J Arbeitskreis Innovative Technologien; Unternehmerverband Brandenburg e.V. %T Untersuchung und Vorhersage des Abbaus von Polymeren mit Hilfe von 2D Systemen %U %X %0 conference poster %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J AFPM - Advanced Functional Polymers for Medicine 2019 %T Towards a prediction of polymer degradation with Langmuir monolayer degradation experiments %U %X %0 conference lecture %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J 16th European Conference on Organized Films (ECOF) %T Langmuir monolayers as tool to predict the degradation of architectured macromolecules %U %X %0 conference poster %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J Polydays 2019 - Polymer Science and Engineering in View of Digitalization %T Towards a prediction of polymer degradation with quantitative analysis of Langmuir monolayer degradation experiments %U %X %0 journal article %@ 1022-1336 %A Machatschek, R., Schulz, B., Lendlein, A. %D 2019 %J Macromolecular Rapid Communications %N 1 %P 1800611 %R doi:10.1002/marc.201800611 %T Langmuir Monolayers as Tools to Study Biodegradable Polymer Implant Materials %U https://doi.org/10.1002/marc.201800611 1 %X Langmuir monolayers provide a fast and elegant route to analyze the degradation behavior of biodegradable polymer materials. In contrast to bulk materials, diffusive transport of reactants and reaction products in the (partially degraded) material can be neglected at the air–water interface, allowing for the study of molecular degradation kinetics in experiments taking less than a day and in some cases just a few minutes, in contrast to experiments with bulk materials that can take years. Several aspects of the biodegradation behavior of polymer materials, such as the interaction with biomolecules and degradation products, are directly observable. Expanding the technique with surface‐sensitive instrumental techniques enables evaluating the evolution of the morphology, chemical composition, and the mechanical properties of the degrading material in situ. The potential of the Langmuir monolayer degradation technique as a predictive tool for implant degradation when combined with computational methods is outlined, and related open questions and strategies to overcome these challenges are pointed out. %0 conference lecture %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2018 %J XXVII International Materials Research Congress - IMRC 2018 %T Langmuir monolayers as tools to study molecular degradation of aliphatic polyesters %U %X chains can be calculated from the area reduction curves. %0 conference poster %@ %A Bhuvanesh, T., Machatschek, R., Schulz, B., Nie, Y., Ma, N., Lendlein, A. %D 2018 %J Joint Conference of Three Societies: European Society of Clinical Hemorheology and Miclrocirculation, International Society of Biorheology, International Society of Clinical Hemorheology, ESCHM-ISB-ISCH 2018 %T A facile way to archive biomimetic laminin networks on substrates %U %X %0 conference lecture %@ %A Machatschek, R., Schulz, B., Lendlein, A. %D 2018 %J 27th International Materials Research Congress %T The influence of pH on the molecular degradation mechanism of PLGA %U %X %0 conference poster %@ %A Tarazona, N.A., Machatschek, R., Schulz, B., Prieto, M.A. %D 2018 %J Advanced Functional Polymers for Medicine, AFPM 2018 %T Protein-polymer interaction in Langmuir monolayers: the study of a polyhydroxyalkanoate-associated protein %U %X %0 conference poster %@ %A Saretia, S., Machatschek, R., Schulz, B., Lendlein, A. %D 2018 %J Advanced Functional Polymers for Medicine, AFPM 2018 %T Modulating Enzymatic Degradation of Poly(ε-caprolactone) Monolayer at Air-water interface by Two Dimensional Crosslinking %U %X %0 conference poster %@ %A Vijaya Bhaskar, T.B., Machatschek, R., Lysyakova, L., Kratz, K., Schulz, B., Ma, N., Lendlein, A. %D 2018 %J Advanced Functional Polymers for Medicine, AFPM 2018 %T Collagen type-IV Langmuir-Schaefer films as substrates to direct mesenchymal stem cell adherence %U %X %0 journal article %@ 2059-8521 %A Machatschek, R., Schulz, B., Lendlein, A. %D 2018 %J MRS Advances %N 63 %P 3883-3889 %R doi:10.1557/adv.2018.602 %T The influence of pH on the molecular degradation mechanism of PLGA %U https://doi.org/10.1557/adv.2018.602 63 %X Poly[(rac-lactide)-co-glycolide] (PLGA) is used in medicine to provide mechanical support for healing tissue or as matrix for controlled drug release. The properties of this copolymer depend on the evolution of the molecular weight of the material during degradation, which is determined by the kinetics of the cleavage of hydrolysable bonds. The generally accepted description of the degradation of PLGA is a random fragmentation that is autocatalyzed by the accumulation of acidic fragments inside the bulk material. Since mechanistic studies with lactide oligomers have concluded a chain-end scission mechanism and monolayer degradation experiments with polylactide found no accelerated degradation at lower pH, we hypothesize that the impact of acidic fragments on the molecular degradation kinetics of PLGA is overestimated. By means of the Langmuir monolayer degradation technique, the molecular degradation kinetics of PLGA at different pH could be determined. Protons did not catalyze the degradation of PLGA. The molecular mechanism at neutral pH and low pH is a combination of random and chainend-cut events, while the degradation under strongly alkaline conditions is determined by rapid chainend cuts. We suggest that the degradation of bulk PLGA is not catalyzed by the acidic degradation products. Instead, increased concentration of small fragments leads to accelerated mass loss via fast chain-end cut events. In the future, we aim to substantiate the proposed molecular degradation mechanism of PLGA with interfacial rheolo