Valorization of elemental sulfur via catalyst-free polymerization into dynamic poly(glycerol-sulfur) nano-networks for antibacterial and antiviral applications

The growing threat of antimicrobial resistance and viral infections has intensified the demand for adaptive biomaterials that combine intrinsic bioactivity with controlled therapeutic delivery. In parallel, the development of sustainable polymeric materials from abundant and underutilized feedstocks has become an increasingly important objective. Elemental sulfur, an industrial byproduct produced on a megaton scale, represents a highly attractive yet largely untapped building block for functional polymer synthesis. Herein, we report a one-pot, catalyst- and solvent-free copolymerization of glycidol with elemental sulfur to generate poly(glycerol-sulfur) (hPG-Sn), comprising polyglycerol and polysulfide segments. This approach provides a modular route to sulfur-containing polymers while valorizing elemental sulfur as a sustainable feedstock. The resulting polymers spontaneously form nanoscale networks (200–500 nm) in aqueous media. Importantly, the dynamic S–S bonds within the polysulfide segments impart a stimuli-responsive architecture that enables reversible opening and closing of the network pores, thereby facilitating drug loading and subsequent encapsulation and release. Tetracycline-loaded hPG-Sn networks exhibited a ten-fold enhancement in antibacterial efficacy compared with the free drug, while maintaining low cytotoxicity toward human cells. The chemical modularity of the polysulfide domains further enables facile post-functionalization through thiol-disulfide exchange. Functionalization with 11-mercaptoundecanesulfonate (MUS) generated negatively charged nanoparticles (~ 550 nm, ζ = −30 mV) that exhibited pronounced antiviral activity against herpes simplex virus (HSV), including both inhibitory and virucidal effects. Thus, hPG-Sn combines sustainable sulfur utilization, dynamic and reversible pore modulation, efficient therapeutic cargo loading, and facile surface functionalization within a single polymer platform. These features highlight its potential as an adaptable nanomaterial for controlled antimicrobial and antiviral delivery.