Improved anti-Candida activity of hydrogel containing tea tree oil-loaded solid lipid nanoparticles for the treatment of oropharyngeal candidiasis

Abstract

Abstract Objectives Developing a hydrogel containing tea tree oil (TTO) encapsulated in solid lipid nanoparticles (SLNs) to treat oropharyngeal candidiasis. Methods Initially, the TTO chemical composition was evaluated. Next, SLNs containing TTO (TTO-SLNs) were produced and characterized. The TTO-SLNs were incorporated into a hydrogel, and the antifungal activity against Candida spp. was analysed. Finally, the ex vivo permeation was assessed. Key findings The chemical composition of TTO met ISO 4730:2017 standards. The TTO-SLNs were spherical and had a Z-average, PdI, ZP and entrapment efficiency of 135.90 ± 6.65 nm, 0.19 ± 0.04, −31.07 ± 1.05 mV and 92.74% ± 0.01%, respectively. Moreover, TTO-SLNs were stable (no changes in Z-average and PdI) for at least 120 days. In the cytotoxicity evaluation, the samples were considered cytotoxic at the following concentrations: TTO: 125–1000 µg/ml, TTO-SLN: 348–5568 µg/ml of TTO and the control nanoparticle was not cytotoxic. Both TTO-SLNs and the hydrogel containing TTO-SLNs demonstrated fungicidal action against all Candida spp., whilst for TTO, it was found only against C. albicans. The percentage of TTO permeation was 70.52%. Conclusions The hydrogel loaded with TTO-SLNs is a promising tool for TTO delivery, aiming at activity against C. albicans for the treatment of oropharyngeal candidiasis.