Development and testing of repellent formulation using Citrus aurantifolia fruit peel-synthesised silver nanoparticles as personal protection against mosquitoes

Mosquitoes are considered important vectors of several tropical diseases, including filariasis, malaria, chikungunya, dengue, Japanese encephalitis, and yellow fever, which cause millions of deaths yearly. Personal protective measures against mosquito vectors include repellents, widely used to prevent the spread and transmission of mosquito-borne diseases by minimising contact between humans and mosquito vectors. Mosquito repellents are generally classified into two, which include chemical￾based and plant-based repellents. However, both plant and chemical-based repellents have been reported to have shortcomings. For example the chemical-based repellents have allergic or toxic reactions in some individuals, whereas the plant based repellents have a short protection time of less than two hours. Therefore, this study aimed to develop a novel mosquito repellent formulation using Citrus aurantifolia fruit peel (CAFP)-synthesised silver nanoparticles as an active ingredient against adult Aedes mosquitoes to address sustainable development goal aim of good health and well￾being. To achieve this objective, plant extraction and phytochemical screening of Citrus aurantifolia fruit peel plant extract was performed by maceration and standard phytochemical screening methods. Silver nanoparticle synthesis was conducted using Citrus aurantifolia fruit peel extract. The synthesised silver nanoparticles were successfully characterised using UV-visible spectroscopy, high-resolution transmission electron microscope (HR-TEM), field emission scan electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), and dynamic light scattering (DLS). Thereafter, silver nanoparticle-based mosquito repellent lotion was formulated using different percentage of silver nanoparticle (F1-5%, F2-7%, F3-10%), and the physicochemical stability of the formulation was assessed over six months of storage time. The efficacy of the formulation against mosquitoes was determined in laboratory and field conditions. The result of the preliminary phytochemical qualitative screening reveals the presence of seven (7) different phytochemicals such as flavonoids, alkaloids, tannins, saponins, phenols, terpenoids, and steroid. Moreover, The FTIR analysis of the extract revealed the presence of functional groups like hydroxyl, carboxyl, carbonyl, amine, and phenyl, whereas the GC–MS analysis indicated the presence of chemical compounds such as 1,2,4-Benzenetricarboxylic acid, Fumaric acid, nonyl pentadecyl, and 4-Methyl-2-trimethylsilyloxy￾acetophenone, etc., with similar functional groups. The synthesised silver nanoparticle has displayed the characteristics of a surface plasmon resonance (SPR) band peak from 360–405 nm. HR-TEM and FESEM confirm polydisperse, spherical shaped and smooth surface nanoparticles with an average size of 24.023±8.3 nm. EDX analysis further revealed that silver is the most abundant element found in the micrograph of the nanoparticles. FTIR analysis further confirmed the presence of different functional groups on the surface of the nanoparticle. The XRD analysis also confirmed that the nanoparticles synthesised are crystalline. The stability profile obtained during six months of storage revealed that all the formulations exhibited stable physicochemical characteristics such as colour, texture, odour, pH, and zeta potential. However, the formulations stored at high temperature (40±2°C/75±5%) show a slight sign of phase separation. The results observed in this study further indicate that all the formulations exhibited pseudoplastic flow behaviour that assures suitable spreadability on the skin along with accepted physicochemical stability. Furthermore, this study confirms that the rheological response of all formulations depends on the shear rate. The present study further highlights the promising repellent efficacy of silver nanoparticle-based mosquito repellent formulations, achieving over 90% protection initially and maintaining more than 60% effectiveness by the end of the observation period. In comparison, a 20% DEET formulation (positive control) offers complete protection for up to one hour and retains over 80% efficacy even after 5-6 hours. Notably, some commercial repellents, such as Autan® (a Citrodiol PMD-based product), demonstrate comparable effectiveness to the silver nanoparticle formulation. Additionally, the study reveals the potential of using Citrus aurantifolia fruit peel extract for the green synthesis of silver nanoparticles, promoting sustainable practices i.e responsible consumption and production. Overall, these findings underscore the promising mosquito repellent properties of silver nanoparticles, positioning them as a viable alternative to both plant-based and synthetic chemical repellents.

Text FPSK (p) 2024 20 - Declaration Form.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (417kB) Text FPSK (p) 2024 20 - Full Text.pdf Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (59MB) Text FPSK (p) 2024 20.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (59MB)

Actions (login required)

View Item