Green-Nanoarchitectonics for Sub-2 nm Ag Nanoparticles on Attapulgite Enables Biocryogel with Synergistic and...

The rising prevalence of multidrug-resistant wound infections demands innovative therapeutic strategies that simultaneously eradicate pathogens and orchestrate the complex immune healing process. This study presents an innovative green strategy for the in situ anchoring of ultrasmall (1.26 ± 0.3 nm), highly dispersed silver nanoparticles (AgNPs) on attapulgite (APT) nanorods mediated by a Paeonia lactiflora Radix extract. The resulting AgNPs/APT nanocomposite was further integrated into the physically cross-linked network of carboxymethyl chitosan (CMC) and κ-carrageenan (KCG) to fabricate a multifunctional composite cryogel (CMC/KCG/AgNPs/APT). The composite cryogel exhibited enhanced antibacterial efficacy against multidrug-resistant bacteria and biofilms and a well-balanced combination of mechanical strength, rapid fluid absorption, and biocompatibility, resulting from the dual role of APT in conferring mechanical robustness to the polymer matrix and confining the size of AgNPs to the ultrasmall regime for augmented biological functions. Moreover, this composite cryogel demonstrated unique properties of polarizing the pro-inflammatory M1 phenotype into the pro-healing M2 phenotype with CD163⁺ cells increasing by 2.6 times, effectively inhibiting inflammatory factors (TNF-α and iNOS) and promoting fibroblast migration. In a full-thickness skin defect model infected with A. baumannii, this multimodal synergy culminated in a significantly enhanced wound healing rate of 95.34 ± 2.9% within 14 days. This study proposes a novel strategy that synergistically integrates metal nanomaterials, natural clay, and biological polysaccharides, thereby offering a promising solution to the longstanding issues of antibacterial efficacy, biological safety, and immune regulation balance in infected wound management.