Mosquito-repellent controlled-release formulations for fighting infectious diseases

Abstract

Malaria is a principal cause of illness and death in countries where the disease is endemic. Personal protection against mosquitoes using repellents could be a useful method that can reduce and/or prevent transmission of mosquito-borne diseases. The available repellent products, such as creams, roll-ons, and sprays for personal protection against mosquitoes, lack adequate long-term efficacy. In most cases, they need to be re-applied or replaced frequently. The encapsulation and release of the repellents from several matrices has risen as an alternative process for the development of invention of repellent based systems. The present work reviews various studies about the development and use of repellent controlled-release formulations such as polymer microcapsules, polymer microporous formulations, polymer micelles, nanoemulsions, solid-lipid nanoparticles, liposomes and cyclodextrins as new tools for mosquito-borne malaria control in the outdoor environment. Furthermore, investigation on the mathematical modelling used for the release rate of repellents is discussed in depth by exploring the Higuchi, Korsmeyer-Peppas, Weibull models, as well as the recently developed Mapossa model. Therefore, the studies searched suggest that the final repellents based-product should not only be effective against mosquito vectors of malaria parasites, but also reduce the biting frequency of other mosquitoes transmitting diseases, such as dengue fever, chikungunya, yellow fever and Zika virus. In this way, they will contribute to the improvement in overall public health and social well-being.

Keywords: Kinetic model; Malaria; Mosquito repellent, controlled‐release formulations; Vector control.

Fig. 1

Different systems of controlled-repellent-release [35]. Republished with permission from Elsevier

Fig. 2

Example of a polymer microcapsule containing oil, where the core and wall or shell are clearly visible [26]. Republished with permission from reference

Fig. 3

Example of an oil controlled-release mechanism through a polymer microcapsule wall [26]. Republished with permission from reference

Fig. 4

Optical (a) and SEM (b) micrographs of thyme oil/poly(lactic acid) microcapsules [39]. Republished with permission from Taylor & Francis

Fig. 5

Fluorescence confocal micrographs of the thyme oil/PLA microcapsules: a Core and wall are clear visible; while b wall or shell polymer is visible [39]. Republished with permission from Taylor & Francis

Fig. 6

Nanoemulsion structure comprising: a oil-in-water emulsion (left), and b water-in-oil emulsion (right) [49]. Republished with permission from Elsevier

Fig. 7

Example of a pseudo-ternary phase diagram of a simple four-component microemulsion (surfactant, cosurfactant, oil and water), at constant temperature and pressure. (1 ɸ): one phase; (2 ɸ): two phases [51]. Republished with permission from Elsevier

Fig. 8

TEM micrographs of nanoemulsions with several oils: a phenyl trimethicone, b polydimethylsiloxane, c cetyl ethylhexanoate, d dioctanoyl-decanoyl-glycerol, e isopropyl myristate, and f liquid paraffin. Scale bars: 150 nm [48]. Republished with permission from American Chemical Society (ACS)

Fig. 9

Optical micrographs of the oil-in-water embryonic emulsions containing a 1:10 mixture of blend poly(ethylene oxide)/poly(ε-caprolactone) and phenyl trimethicone oil in the organic phase. Scale bars: 5 μm [48]. Republished with permission from American Chemical Society (ACS)

Fig. 10

Relationship of protection time and release rate of citronella oil in a nanoemulsion at varying concentration of glycerol (black circle) and surfactant (white circle) [56]. Republished with permission from Elsevier

Fig. 11

Solid lipid nanoparticle structure [62]. Republished with permission from Elsevier

Fig. 12

a SEM micrograph of neem seed oil loaded solid lipid nanoparticles [65] and b TEM micrograph of essential oil into solid lipid nanoparticles [66]. Republished with permission from Elsevier

Fig. 13

Structure of repellent (essential oil) based polymer micelles [79]. Republished with permission from reference

Fig. 14

a SEM micrographs of DEPA-based micellar- polymer system. The presence of a dense polymeric sheath of polymer was confirmed. b TEM micrographs of DEPA-based micellar-polymer system. The presence of a discontinuous polymeric layer was revealed [78]. Republished with permission from Elsevier

Fig. 15

An example of drug (i.e. repellent) encapsulation in cyclodextrin at a 1:1 ratio [81]. Republished with permission from Elsevier

Fig. 16

SEM micrographs of a ß-cyclodextrin and repellent essential oil based on ß-cyclodextrin inclusion complex [83]. Republished with permission from Elsevier

Fig. 17

Phase diagram of the system linear low density polyethylene (LLDPE)/citronellal [14]. Republished with permission from Elsevier

Fig. 18

Schematic of a cylinder-shaped microporous membrane strand filled with repellent [14]. Republished with permission from Elsevier

Fig. 19

a SEM micrographs showing the internal structure of an extruded microporous LLDPE strap that contains 30 wt% DEET (an effective insect repellent), b the outer surface appearance of the skin [14]. Republished with permission from Elsevier

Fig. 20

Sketch of well-dispersed exfoliated (isolated) and suitable oriented clay platelets in a polymer matrix, for control of the effective diffusion path for the repellent

Fig. 21

The constant release of repellents based on microporous poly(ethylene-co-vinyl acetate) (EVA) and linear low-density polyethylene (LLDPE) strands [14]. Republished with permission from Elsevier

Fig. 22

Evaporation rate of mosquitoes repellents measured at 50 °C [151]. Republished with permission from Wiley

Fig. 23

Experimental data of the repellent microcapsules release (symbols) and prediction data estimated using the Higuchi model [29]. Republished with permission from reference

Fig. 24

Experimental data of release rate of encapsulated DEET during three temperatures 40, 60, and 90 °C and prediction data predicted using Korsmeyer-Peppas model [169]. Republished with permission from Wiley

Fig. 25

Experimental and predicted release rate profile of DEET from MICs [44]. Republished with permission from Elsevier

Fig. 26

Experimental data of release rate of repellents from microporous LLDPE strands evaluated at 50 °C and estimation data predicted using Eq. (6) [151]. Republished with permission from Wiley