Donnan-like effect driven synthesis of brush-confined Prussian blue Nanozymes with low crystallinity for...

Prussian blue nanozymes (PBNZ) have emerged as promising biomedical agents due to their enzyme-mimetic activities, photothermal properties, and magnetic resonance imaging (MRI) contrast capabilities. However, their practical utility is limited by aggregation tendencies arising from high surface energy. Here, we present a strategy employing spherical polyelectrolyte brushes (SPB) as nanoreactors to synthesize satellite-structured SPB@PBNPs with well-defined dimensions (15-19 nm) and low crystallinity. Through systematic optimization of the m_Fe³⁺/m_SPB ratio (1, 4) and acidic co-precipitation conditions, uniform anchoring of PBNPs on SPB surfaces was achieved. Comprehensive characterization, including TEM, FTIR, XRD, DLS, and UV-vis, confirmed the structural integrity and monodispersity of the hybrid system. Analysis of crystal growth indicated a nonclassical crystallization pathway, driven by Donnan-like effect mediated Fe³⁺ confinement at SPB interfaces, which facilitated heterogeneous nucleation and oriented nanoparticle attachment. The three-dimensional brush architecture endowed SPB@PBNPs with remarkable environmental stability across a broad pH range (3.0-7.0) and temperature range (4-60 °C). Enzymatic assays demonstrated enhanced catalytic performance compared to conventional PBNPs (74 nm), exhibiting 3.7-fold enhanced peroxidase-like activity and 3-fold elevated catalase-like activity, attributed to optimized electronic structures and increased active site accessibility due to reduced crystallinity. Furthermore, SPB@PBNPs displayed exceptional photothermal conversion efficiency (60.4 %), MRI contrast capability (r₁ = 0.8406 mM^-1·s^-1), and good biocompatibility. This work elucidates the crystallization dynamics and catalytic enhancement mechanisms of brush-stabilized nanozymes, offering a robust framework for designing multifunctional nanozymes with synergistic catalytic efficiency and environmental resilience.