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 DSTs 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 degrees 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.