Tunable PEGylation platform for efficient siRNA delivery using mesoporous silica nanoparticles

Poly(ethylene glycol) (PEG) coatings are widely used to improve nanoparticle stability and biocompatibility, yet conventional PEGylation methods rely on multi-step conjugation that limits reproducibility and restricts control over charge-shielding balance critical for siRNA delivery. Here, we present a composition-tunable PEGylation strategy based on poly(2-(dimethylamino)ethyl methacrylate-co-poly(ethylene glycol) methacrylate) (poly(DMAEMA-co-PEGMA), hereafter referred to as AP) copolymers for the efficient delivery of PD-L1 siRNA using mesoporous silica nanoparticles (MSNs). Copolymers with varying DMAEMA: PEGMA ratios (2:1, 1:1, 0.5:1) and PEG chain lengths (Mn 450 or 950 Da) were synthesized via one-step free-radical polymerization, enabling precise tuning of surface charge and steric stabilization. The optimized MSN/copolymer complexes exhibited enhanced siRNA loading, colloidal stability, and serum resistance while maintaining favorable cytocompatibility. Cellular studies demonstrated improved uptake and significant PD-L1 gene silencing. This work establishes a composition-tunable and scalable PEGylation platform that overcomes the limitations of conventional surface modification and provides a potential strategy for siRNA-based applications.