Physicochemical and Functional Characterization of Chitosan Prepared From Shrimp Shells and Investigation of Its Antibacterial, Antioxidant and Tetanus Toxoid Entrapment Efficiency

Abstract

The objective of this research was to extract chitosan from shrimp shells involving demineralization, deprotenization, decolorization and deacetylation processes and to investigate its physicochemical, antioxidant, antibacterial and pharmaceutical properties in comparison with commercially available acetic acid soluble chitosan (C1) and water soluble chitosan (C2). Prepared chitosan (C3) showed 75% DD by FT-IR spectra indicating its solubility in 1% acetic acid while higher degree of deacetylation 85% was observed for C2. Similarly, the viscosity 602 cps and viscosity-average molecular weight 1249 kDa were also significantly higher for C2 compared to C1 and C3. Among the micrometric properties bulkiness and turbidity was significantly higher for C3 and tapping density (0.47 g/ml), Carr’s index (25%) and Hausner’s ratio (1.33) were higher for C1 suggesting its overall good flow properties. Similarly FBC and WBC were significantly higher for C3. Significant differences (P<0.05) were observed in all three chitosan samples for free radical scavenging activity being higher for C3, suggesting it as a good antioxidant source. Also, C3 showed higher antimicrobial activity against both gram positive and gram negative bacteria. Weight loss was up to 51% for C3 by thermo gravimetric analysis revealing its relatively lower thermal stability as compared to both C1, C2 having weight loss up to 41%. Placebo microspheres showed smooth uniform surfaces, whereas, rough surfaces were obtained for tetanus toxoid encapsulated microspheres as confirmed by SEM for all the chitosan samples. The particle size of formulated chitosan microsphere was ranging between 5−50 µm and their tetanus toxoid entrapment efficiency obtained were 89%, 81% and 84% respectively for C1, C2 and C3. Thus, overall results for chitosan prepared from shrimp shells suggested that it has good micrometric properties and functional properties which can be used as an antimicrobial, antioxidant and a pharmaceutical molecule for mucosal vaccine development.