M. Joyce Nirmala

Ultrasonic emulsification of eucalyptus oil nanoemulsion: antibacterial activity against Staphylococcus aureus and wound healing activity in Wistar rats.

The plant derived essential oil nanoemulsion was prepared using a mixture of components containing eucalyptus oil as organic phase, water as continuous phase, and non ionic surfactant, Tween 80, as emulsifier at a particular proportion of 1:1 v/v%. The ultrasonication was applied for varied processing time from 0 to 30 min to study the effect of time on the formation of nanoemulsion and physical stability of formulation by this method. The transparency and stability of emulsion was enhanced when the sonication time was increased compared to hand blender emulsion. The most stable nanoemulsion was obtained in 30 min sonication having the mean droplet diameter of 3.8 nm. The antibacterial studies of nanoemulsion against Staphylococcus aureus by time kill analysis showed complete loss of viability within 15 min of interaction. Observations from scanning electron microscopy of treated bacterial cells confirmed the membrane damage compared to control bacteria. Furthermore, the wound healing potential and skin irritation activity of the formulated nanoemulsion in Wistar rats, suggested non-irritant and higher wound contraction rate with respect to control and neomycin treated rats. These results proposed that the formulated system could be favourable for topical application in pharmaceutical industries.

Cytotoxicity of TiO2 nanoparticles and their detoxification in a freshwater system

In the current study, two aspects concerning (i) the cytotoxicity potential of TiO₂ nanoparticles (NPs) toward freshwater algal isolate Scenedesmus obliquus and (ii) the potential detoxification of NPs by the microalgae were assessed under light (UV-illumination) and dark conditions at low exposure levels (≤1 μg/mL), using sterile freshwater as the test medium. The statistically significant reduction in cell viability, increase in reactive oxygen species production and membrane permeability (light vs. dark) suggested photo-induced toxicity of TiO₂ NPs. The electron micrographs demonstrated adsorption of the NPs onto the cell surface and substantiated their internalization/uptake. The fluorescence micrographs and the confocal laser scanning (CLSM) images suggested the absence of a definite/intact nucleus in the light treated cells pointing toward the probable genotoxic effects of NPs. In a separate three cycle experiment, a continuous decrease in the cytotoxicity was observed, whereas, at the end of each cycle only fresh algae were added to the supernatant containing NPs from the previous cycle. The decreasing concentrations of the NPs in the subsequent cycles owing to agglomeration-sedimentation processes exacerbated by the algal interactions played a crucial role in the detoxification. In addition, the exo-polymeric substances produced by the cells could have rendered the available NPs less reactive, thereby, enhancing the detoxification effects.

Improved efficacy of fluconazole against candidiasis using bio‐based microemulsion technique

Candida albicans is a common fungal pathogen that causes systemic and superficial infections in most immunocompromised patients. Fluconazole, a synthetic triazole antifungal agent, is the most prescribed drug used in treating this pathogen. But because of its poor solubilization in water and the emergence of resistant strains against this antimycotic drug, we aimed at devising a unique microemulsion drug delivery system for fluconazole against candidiasis. A clear oil‐in‐water microemulsion system, consisting of clove oil as oil phase, Tween 20 as surfactant, and water as aqueous phase was developed using a ternary phase diagram. Physicochemical characterization was done to understand the internal physicochemical state. The bulk drug, fluconazole, that measured several microns in length was reduced to a 10–65 nm range with no means of high‐energy methods as confirmed by transmission electron microscopy. The very small and uniform spherical structure of the drug‐loaded microemulsion system could be of high impact to the biological system as the efficacy of fluconazole is greatly improved when compared with its conventional bulk form. The optimized microemulsion exhibited significantly higher antifungal activity at a minimum concentration (8 µg/ml) of fluconazole as examined by fluorescence and scanning electron microscopy. Thus, our report discloses an excellent oral drug delivery system.