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

Abstract

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.