Synthesis, characterization, and antibacterial activity of amino-functionalized microcrystalline cellulose derivatives from cotton fibers

This study aims to develop a green and efficient method for synthesizing antimicrobial amino-functionalized microcrystalline celluloses from cotton fibers. Microcrystalline cellulose was prepared by acid hydrolyzing of cellulose. Tosyl cellulose was synthesized by tosylation of cellulose in an eco-friendly medium using NaOH/urea and decyl glucoside surfactant with DS Ts of 0.51. Three amino-functionalized cellulose derivatives were synthesized by nucleophilic substitution reaction of tosyl cellulose with 3-aminopropyltrimethoylsilane, ethylenediamine, and triethylenetetramine. The physicochemical properties of investigated celluloses were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, and thermogravimetric analysis-differential scanning calorimetry. Microcrystalline cellulose with high crystallinity index (81.90%) and crystalline size of 0.30 nm was isolated from cotton fibers. After the dissolution and chemical modification, the crystalline form of cellulose was transformed from cellulose I to amorphous cellulose II. The thermal degradation of aminated cellulose was around 260 °C. The amino cellulose exhibited high inhibition activity against S. aureus , P. aeruginosa , and E. coli with MIC values less than 5 mg mL –1 . The chemical modification of surface cellulose could deliver antimicrobial cellulosic materials with potential applications for air and water treatments or as ingredients in the food, cosmetic, and pharmaceutical industries.