H2O2-driven dual-functional modification of Tremella fuciformis polysaccharides: Molecular weight reduction and oxidative group engineering for multidimensional bioactivity control.

High molecular weight and inert functional groups limit the biomedical utility of natural polysaccharides, such as Tremella fuciformis polysaccharides (TFPs). In this study, we describe a H2O2-driven, one-step method for the concurrent oxidation and degradation of TFPs, which reduces the molecular weight from 1079.6 to 4.6 kDa while introducing aldehyde (0 %-0.99 %) and carboxyl (1.22 %-9.80 %) groups. By altering the H2O2 concentration, we obtained oxidized TFPs (OTFPs) with defined properties, namely OTFP-1 (13.5 kDa, 0.36 % aldehyde) exhibiting low cytotoxicity (73 % viability at 15 mg/mL); OTFP-3 (5.0 kDa, 0.80 % aldehyde) exhibiting enhanced antioxidant (DPPH/ABTS: 83 %/89 %), anti-inflammatory (IL-6/TNF-α reduction: 46 %/53 %), and ultraviolet B repair (36 % recovery) activities; and OTFP-4 (4.6 kDa, 0.99 % aldehyde) displaying broad-spectrum antibacterial activity (minimum inhibitory concentration: 7-9 mg/mL). The aldehyde groups also yielded injectable, self-healing hydrogels through dynamic Schiff base bonds. This green strategy decouples molecular weight and functionalization and provides a versatile platform for tailored bioactive materials.