Development of Mosquito Repellent for Textile Application With Citronella Oil Encapsulated With Carboxymethylated Tamarind Gum

Abstract

Dengue is a mosquito-borne viral disease that has rapidly spread across all regions of Southeast Asia in recent years. This study aimed to develop a long-lasting, naturally-derived mosquito-repellent cotton textiles by encapsulating citronella oil within a novel biopolymer wall material based on carboxymethylated tamarind gum (CTG), a low-cost, biocompatible polysaccharide whose anionic carboxymethyl groups improve solubility, film-forming ability, and hydrogen-bonding affinity for cotton cellulose. Citronella oil was emulsified with CTG at three gum/oil (G/O) mass ratios (0.87, 1.14 and 1.25) and spray-dried to produce CTG—citronella microcapsules. The repellent activity of treated cotton textiles (5 × 5 cm) was evaluated by a human-arm-in-cage assay (100 female Aedes aegypti) using three application methods: (i) immersion in a microcapsule bath, (ii) sprinkling of microcapsules onto textile pre-coated with 5 wt% CTG solution, and (iii) direct application of pure citronella oil. Cotton treated with pure citronella oil maintained repellency above 80% for approximately 2 weeks, whereas textiles treated with CTG—citronella microcapsules by sprinkling and immersion sustained > 80% repellency for at least 3 weeks and regression analysis to predict the values for future days measurable protection for up to 40 and 44 days, respectively. The CTG shell limits diffusion and oxidative loss of the volatile terpenes (citronellal, citronellol, geraniol), thereby extending the release lifetime well beyond that of the unencapsulated oil. The work confirms the feasibility of CTG as an effective and low-cost wall material for the textile-based delivery of essential oils.