Karen Wooley

Mussel-inspired, catechol-functionalized polypeptides were synthesized from natural feedstocks and investigated as redox-active organic electrode materials, to combine electrochemical performance with sustainability and cytocompatibility. Postpolymerization grafting of dopamine onto pre-established poly­(α-l-glutamic acid)­s resulted in low conjugation, giving poor aqueous solubility and failing to function electrochemically in initial solution-state studies. Therefore, a direct strategy was adopted, whereby the redox-active catechol functionality was embedded into the monomer, followed by ring-opening polymerization to afford a polypeptide bearing a catechol group at each repeat unit. In the solid state, WAXS revealed short-range order, thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC) indicated thermal stability and low flammability, and electrochemical evaluation demonstrated a quasi-reversible catechol/o-quinone aqueous redox process. The composite thin film electrochemical signal intensity was significantly greater for this poly­(l-DOPA) than for the original catechol-grafted poly­(α-l-glutamic acid). Cell-viability assays further support these catechol-functionalized polypeptides as viable components in sustainable and safe energy storage media.

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Synthetic polymers have revolutionized modern society, underpinning industries from packaging to healthcare and shaping everyday life. However, their petroleum-based origins carry significant environmental footprints, from greenhouse gas emissions to persistent pollution and waste. While significant advances have been made in developing sustainable, functional, and regenerative polymers, critical challenges remain.This Voices asks: what innovations have inspired breakthroughs, and what additional progress are needed toward truly sustainable polymers?

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Regenerative strategies for bone repair would benefit from scaffolds that are mechanically resilient and biologically compatible. We present a fully bioderived and 3D-printable composite scaffold that meets these requirements while offering environmental sustainability through the integration of CO₂-derived eugenol polycarbonate, bioderived cross-linkers, and hydroxyapatite (HAp) reinforcement. This scaffold exhibits excellent thermal stability (T_g ≥ 60 °C and T_d ≥ 350 °C) and robust mechanical properties (flexural modulus ∼ 2.54 GPa and compressive modulus ∼ 220 MPa), aligning with the mechanical properties of human trabecular bone and outperforming reported polymer/HAp composites. It demonstrates exceptional creep resistance (∼0.82% strain under 3 MPa for 24 h), ensuring long-term mechanical integrity under physiological loads. A UV-assisted direct ink writing (DIW) technique, followed by post-UV curing, fabricates precise 3D structures that support cell attachment. The hydrophilicity of the scaffold is tunable via surface modifications to optimize cell-material interactions. In vitro cytocompatibility studies using MC3T3 preosteoblasts show >91% viability. Under simulated physiological conditions (PBS, 37 °C), the scaffold shows negligible mass loss over 18 weeks. Compared to conventional 3D-printed scaffolds that rely on petrochemical feedstocks and exhibit weaker mechanical resilience, this sustainable system offers a compelling combination of printability, mechanical robustness, and biocompatibility with potential for advanced bone regenerative therapies.

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