Sulfonated hyperbranched polymers were recently reported to efficiently mimic cellulase activity, producing large quantities of glucose from cellulose.

Novel, nontoxic star copolymers of N,N-dimethylaminoethyl methacrylate (DMAEMA) and hydroxyl-bearing oligo(ethylene glycol) methacrylate (OEGMA-OH) were synthesized via atom transfer radical polymerization (ATRP) using hyperbranched poly(arylene oxindole) as the macroinitiator. Stars with molar masses from 100,000 g/mol to 257,000 g/mol and with various amounts of OEGMA-OH in the arms were prepared. As these polymers can find applications, e.g., as carriers of nucleic acids, drugs or antibacterial or antifouling agents, in this work, much attention has been devoted to exploring their solution behavior and their stimuli-responsive properties. The behavior of the stars was studied in aqueous solutions under various pH and temperature conditions, as well as in PBS buffer, in Dulbecco’s modified Eagle’s medium (DMEM) and in organic solvents for comparison. The results indicated that increasing the content of hydrophilic OEGMA-OH units in the arms up to 10 mol% increased the cloud point temperature. For the stars with an OEGMA-OH content of 10 mol%, the thermo- and pH-responsivity was switched off. Since cytotoxicity experiments have shown that the obtained stars are less toxic than homopolymer DMAEMA stars, the presented studies confirmed that the prepared polymers are great candidates for the design of various nanosystems for biomedical applications.

The thermo-responsive behavior of Poly(N-isopropylacrylamide) makes it an ideal candidate to easily embed cells and allows the polymer mixture to be injected. However, P(NiPAAm) hydrogels possess minor mechanical properties. To increase the mechanical properties, a covalent bond is introduced into the P(NIPAAm) network through a biocompatible thiol-ene click-reaction by mixing two polymer solutions. Co-polymers with variable thiol or acrylate groups to thermo-responsive co-monomer ratios, ranging from 1% to 10%, were synthesized. Precise control of the crosslink density allowed customization of the hydrogel’s mechanical properties to match different tissue stiffness levels. Increasing the temperature of the hydrogel above its transition temperature of 31 °C induced the formation of additional physical interactions. These additional interactions both further increased the stiffness of the material and impacted its relaxation behavior. The developed optimized hydrogels reach stiffnesses more than ten times higher compared to the state of the art using similar polymers. Furthermore, when adding cells to the precursor polymer solutions, homogeneous thermo-responsive hydrogels with good cell viability were created upon mixing. In future work, the influence of the mechanical micro-environment on the cell’s behavior can be studied in vitro in a continuous manner by changing the incubation temperature.

Despite decades of advancements in melt electrowriting (MEW) and electrospinning (ES), poly( ϵ -caprolactone) (PCL) remains the gold standard polymer for these techniques. Its widespread use is attributed to its processability in both melt and solution, thermal stability, and low melting temperature. MEW and ES enable the fabrication of micro- and nanofibrous scaffolds that can mimic the extracellular matrix of specific tissues. This makes them especially attractive for biomedical applications. However, PCL lacks key properties, e.g., elasticity and suitable biodegradation time, for soft tissue applications. We report for the first time the successful introduction of α -amino acid-based poly(ester amide)s (AAA-PEAs) for MEW processing. Additionally, ES outcomes have been improved compared to existing literature. These polymers were synthesized via polycondensation containing ester and amide functionalities, yielding high molar masses (>40 kg mol ⁻¹ ). L-alanine and L-phenylalanine were selected as α -amino acids, differing in hydrophobic side groups (methyl vs benzyl), resulting in distinct material properties. Both AAA-PEAs showed excellent ES processability, producing uniform fibers (1–3 μ m) without the need of adding PCL. Notably, only the phenylalanine-based PEA was so far processable by MEW, yielding smooth, uniform fibers (25–30 μ m) with no pulsing, fusing, or surface defects. As proof-of-concept, excellent stacking behavior up to 15 layers was achieved. Scaffolds exhibited enhanced ultimate tensile strength (13.70 ± 1.60 MPa) and accelerated biodegradation (72%–77% remaining mass after 16 weeks in phosphate buffered saline at 37 °C) compared to PCL. In vitro studies with MC3T3-E1 cells confirmed cytocompatibility. The above findings underscore the potential of AAA-PEAs as promising biomaterials for soft tissue biomedical applications.