Microwave‐assisted degradation of chitosan with hydrogen peroxide treatment using Box‐Behnken design for enhanced antibacterial activity

Abstract

SummaryLow molecular mass (MM) chitosan with high degree of deacetylation (DDA) has excellent bioactivity including antioxidant, antibacterial and encapsulation properties. In this work, to reduce the MM of chitosan, microwave-assisted heating treatment (MAHT) conditions were investigated using three factors at three levels Box-Behnken design (BBD). Microwave heating (MH) time, H 2 O 2 concentration and solid-toliquid ratio significantly affected the DDA and MM of chitosan. The antibacterial activities of chitosan before and after degradation were investigated based on minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results showed that a second-order polynomial equation fitted the observed values using multiple regression analysis and had a high coefficient of determination (R 2 = 0.9591 and 0.9161 for the DDA and MM of chitosan, respectively). An optimisation study was performed using Derringer's desirability function methodology, and the optimal conditions were 80-s MH time, 1.5% H 2 O 2 concentration and 1:40 solid-to-liquid ratio. The MIC and MBC of chitosan before and after degradation against Escherichia coli and Salmonella typhimurium were 0.031 and 0.063 mg mL À1 , and 0.25 and 0.125 mg mL À1 , respectively. The optimised DDA and MM of chitosan were 90.58 AE 2.04% and 124.25 AE 14.36 kDa, respectively, which significantly reduces the use of oxidant reagent.

Characterizations and Antibacterial Efficacy of Chitosan Oligomers Synthesized by Microwave-Assisted Hydrogen Peroxide Oxidative Depolymerization Method for Infectious Wound Applications

“…The average M w of OCS reduced significantly from 7 kDa to 2 kDa as H 2 O 2 concentration increased from 5% to 15%. The trend is similar to previous studies employing microwave-assisted H 2 O 2 treatment under different experimental conditions (i.e., H 2 O 2 concentration, microwave reaction time, microwave power, and so on) [ 20 , 23 , 37 ]. In this study, we used a relatively high concentration of H 2 O 2 that significantly reduced the reaction time to only 3 min as compared to the previous study that used a low concentration of H 2 O 2 and required a longer reaction time (more than 10 min) to obtain OCS of less than 2 kDa [ 20 ].…”

“…In this study, we used a relatively high concentration of H 2 O 2 that significantly reduced the reaction time to only 3 min as compared to the previous study that used a low concentration of H 2 O 2 and required a longer reaction time (more than 10 min) to obtain OCS of less than 2 kDa [ 20 ]. Further, the DD and the M w of OCS5% obtained in this study was much higher and lower, respectively, compared to these values reported in Zhang et al that used shorter microwave time (75 s) although higher microwave power (650 W) and lower H 2 O 2 concentration (2%) [ 37 ].…”

Inhibition of selected pathogens inoculated on the surface of catfish fillets by high molecular weight chitosan coating

“…Chitosan, a deacetylated derivative of chitin, is a natural biopolymer (No et al ., ; Feng et al ., ) that has been extensively studied for their antimicrobial and antifungal activities (No et al ., ; Kong et al ., ; Khan et al ., ; Zhang et al ., ). The antimicrobial activity of chitosan can be affected by intrinsic factors (molecular weight, (MW), degree of deacetylation (DD), solubility, etc.…”

Antimicrobial activities of high molecular weight water‐soluble chitosans against selected gram‐negative and gram‐positive foodborne pathogens

“…However, other viable alternative sources of chitin and chitosan have recently been explored, including resting eggs of Daphnia longispina (fresh water crustacean; Kaya et al ., ), pens of Illex argentinus (Vázquez et al ., ), biomass of Aspergillus niger (Abdel‐Gawad et al ., ) and exoskeleton of two‐spotted field cricket ( Gryllus bimaculatus ; Kim et al ., ). Chitosan and its derivatives have been extensively studied for their antimicrobial activity (Tsai & Su, ; Khan et al ., ; Zhang et al ., ) in addition to their bioactive properties including biodegradability, non‐toxicity, biocompatibility and haemostatic activity (Gallyamov et al ., ; Singh et al ., ). Although the exact mode of action is still inconclusive, the commonly proposed model of chitosan antimicrobial activity suggests that the polycationic amines on the surface of chitosan are positively charged and interact with the negatively charged bacterial cell membranes (Kumar et al ., ; Chouljenko et al ., ).…”