An optimized chitosan/alginate-based microencapsulation of lime peel essential oil and its application as an antibacterial textile

A functional textile immobilized by microcapsules of the lime peel essential oils of C. aurantifolia (LPEO) was prepared and characterized. A varied amount of Chitosan/Alginate (CH/AG) ratios, followed by a mass of LPEO and concentration of sodium tripolyphosphate (STPP) crosslinker, was optimized sequentially to coacervate LPEO using a Tween 80 emulsifier. An antibacterial assay against both Gram-positive and Gram-negative bacteria was further evaluated for the embedded microcapsules. The LPEO (0.2 g) was effectively coacervated by CH/AG (5:3) crosslinked by 2% of STTP to give a yield, oil content (OC), and encapsulation efficiency (EE) of 53.45 ± 2.16%, 65.08 ± 2.60% and 85.04 ± 0.70% respectively. A rough spherical shape of LPEO microcapsules was homogeneously observed with an average particle size of 0.757 mm. An Avrami's kinetic model revealed the release mechanism of the core following zero-order kinetics (k = 1.11 ± 0.13 × 10^-9 s^-1, Ea = 70.21 kJ/mol). The LPEO microcapsules demonstrated good thermal stability up to 122 °C and maintained 38% OC at ambient temperature for four weeks. A 70.34 ± 4.16% of the LPEO microcapsules were successfully overlaid onto the gauze with citric acid binder and sodium phosphate catalyst. Overall, the immobilized microcapsules exhibited strong inhibition against S. aureus and moderate against S. epidermidis, E. coli, and K. pneumonia.