Multifunctional amphiphilic nanoporous Zr-MOFs for detection and degradation of nitrophenols, visual H₂O₂ sensing, and antibacterial applications.

The monitoring and removal of environmental pollutants are critical for the sustainable development of society. Thus far, numerous materials have been developed for either sensing or adsorbing contaminants but integrating these two functions into a single material remains challenging. Most of the current research on nanozymes has focused largely on expensive noble bimetallic catalysts, limiting their practical applications. To address these challenges, the zirconium metal-organic framework (UiO-66-NH) was modified with cost-effective cationic surfactants of various hydrophobic tail lengths (CS-8@Zr-MOF, CS-12@Zr-MOF, and CS-16@Zr-MOF). This modification enhanced water stability, fluorescence properties, and pore size, enabling superior sensing, catalytic and antibacterial performances. The novel CS-8@Zr-MOF, CS-12@Zr-MOF, and CS-16@Zr-MOF materials demonstrated highly sensitive fluorescence detection of toxic nitrophenols through photoinduced electron transfer (PET) mechanism (quenching efficiency ∼ 99 %). Notably, CS-16@Zr-MOF catalyst showed remarkable peroxymonosulfate (PMS) activation ability and could achieve 99 % degradation of nitrophenol within 60 min. Density functional theory (DFT) calculations were utilized to investigate the interaction sites between PMS and CS-16@Zr-MOF (E= ̶ 1.031 eV). Furthermore, we demonstrated the peroxidase-like activity of the modified MOFs and explored the effects of hydrophobicity on their catalytic activity. CS-16@Zr-MOF exhibited excellent nanozyme performance (K = 1.91 mM), which is lower than that of natural horseradish peroxidase (HRP) (3.7 mM). Importantly, MOF/hydrogel kits for portable colorimetric H₂O₂ sensing were developed, utilizing a smartphone for RGB color analysis (LOD ∼0.16 μM). Additionally, the amphiphilic MOF/hydrogel coating demonstrated exceptional biofilm inhibition efficiency (96.7 %) against E.coli, enhancing surface protection in challenging biological environments. The "one-nano MOF-four-functions" design offers significant potential for advanced environmental remediation, artificial nanozymes, and biomedical applications.