Amphiphilic cellulose and alginate-functionalized magnetic ZIF-8 nanocomposites for dinitrophenol removal, colorimetric H2O2 sensing, and antibacterial applications

Abstract

Dinitrophenol (2,4-DNP), hydrogen peroxide (H2O2), and Escherichia coli (E. coli) are hazardous pollutants posing serious risks to both environmental and human health. Although numerous materials have been developed for either sensing or adsorption, integrating these functions into a single, cost-effective, and biocompatible platform remains challenging. Moreover, many reported nanozymes rely on expensive noble metals, which limits their practical applicability. Here, magnetic zeolitic imidazolate frameworks (FesOa/ZIF-8) were functionalized with cost-effective, naturally derived amphiphilic biopolymers, nonionic alginate (AFP) and cationic cellulose (CRQ), to produce multifunctional composites (FesOa/AFP/ZIF-8 and FesOa/CRQ/ZIF-8). The resulting materials were characterized by using 1H NMR, FT-IR, PXRD, TEM, SEM, TGA, and BET analysis. This surface modification simultaneously enhanced the adsorption, catalytic, and antibacterial activities. The intrinsic fluorescence of the amphiphilic biopolymers enabled selective 2,4-DNP detection with a detection limit of 50 nM. FesOa/CRQ/ZIF-8 achieved an adsorption capacity of 103.52 mg g- 1, representing a 121% increase over uncoated FesOa/ZIF-8, and accomplished 98.7% removal at pH 5 (298 K). The nanocomposites also showed excellent peroxidase-like activity (POD) (Km = 1.0 mM) and were successfully embedded in gelatin hydrogels to fabricate low-cost, portable devices for smartphone-assisted H2O2 sensing (limit of detection, LOD = 0.88 mu M). Combined experimental and density functional theory (DFT) analyses elucidated the adsorption and catalytic mechanisms. Furthermore, the nanocomposite hydrogels demonstrated strong antibacterial activity, achieving over 98.52% inhibition against E. coli. This multifunctional platform addresses key limitations of noble-metal-based nanozymes and provides a promising strategy for water purification, environmental remediation, and public health protection.