Microemulsion-Assisted Synthesis of Ni(II)-Grafted Cellulose Metallogel: Structural Insights into a High-Performance...

Area of Science:

• Materials Science
• Catalysis
• Biochemistry

Background:

• Bacterial resistance to antibiotics is a growing global health crisis.
• Novel therapeutic strategies are urgently needed to combat multidrug-resistant pathogens.
• Schiff base complexes and cellulose-based materials offer potential for new antimicrobial agents.

Purpose of the Study:

• To synthesize and characterize a novel nickel(II) Schiff base complex (NC) and its cellulose-grafted metallogel (CNG).
• To evaluate the β-lactamase inhibitory activity of NC and CNG.
• To investigate the mechanism of hydrolysis and factors influencing the activity of CNG.

Main Methods:

• Synthesis of a dinuclear Ni(II) Schiff base complex (NC) and its grafting onto microcrystalline cellulose to form a porous metallogel (CNG) via microemulsion.
• Characterization using XRD, HR-TEM, Raman, XPS, and DFT analyses.
• Evaluation of β-lactamase activity using nitrocefin, with studies on pH dependence, water content, and inhibitor effects.

Main Results:

• CNG exhibited a stable 3D nanostructure with high surface area (240 m²/g) and mechanical stability.
• CNG demonstrated significantly enhanced β-lactamase hydrolytic activity compared to NC, particularly at pH 7.8.
• Hydrolysis mechanism involves Ni(II)-assisted nitrocefin coordination and attack by gel-entrapped water, inhibited by guanidine.

Conclusions:

• The Ni(II)-anchored cellulose metallogel (CNG) is a promising next-generation β-lactamase inhibitor.
• CNG's activity is pH-dependent and influenced by water content, with gel-entrapped water acting as a nucleophile.
• This study presents a novel approach for developing advanced materials to combat antibiotic resistance.