Amphiphilic cellulose and alginate-functionalized magnetic ZIF-8 nanocomposites for dinitrophenol removal,...

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 (Fe₃O₄/ZIF-8) were functionalized with cost-effective, naturally derived amphiphilic biopolymers, nonionic alginate (AFP) and cationic cellulose (CRQ), to produce multifunctional composites (Fe₃O₄/AFP/ZIF-8 and Fe₃O₄/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. Fe₃O₄/CRQ/ZIF-8 achieved an adsorption capacity of 103.52 mg g^-1, representing a 121% increase over uncoated Fe₃O₄/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 μM). 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.