Vulvovaginal candidiasis (VVC) is an infection caused by species from the genus Candida, such as Candida albicans, which affects around 75 % of women at least once in their lives, resulting in annual cost of USD 368 million, only in the United States [1,2]. VVC is characterized by the presence of inflammatory symptoms in the vulva and vaginal mucosa, the main symptoms being itching, pain, and discomfort [3,4]. The treatment includes the use of various antifungal drugs, such as azoles, which is the class with the largest number of drugs [5].

However, current treatments are limited by problems such as resistance, caused by the indiscriminate use of antifungals, and adverse effects such as abdominal pain for systemic agents and burning or irritation for topical agents. These adversities reduce treatment adherence, as well as its effectiveness. This demonstrates the importance of evaluating new therapies that can be used long term [2,6].

Antimicrobial photodynamic therapy (aPDT) has emerged as an alternative treatment strategy. aPDT can act as a microorganism inhibitor. This technique consists of the application of a photosensitizer (PS), a light source that covers the absorption band of the PS, and the presence of oxygen, generating reactive oxygen species (ROS) that are capable of damaging the cellular constituents of fungi [7].

(Hexadecafluorophthalocyanine)‑zinc (PC) is a metallophthalocyanine that absorbs light at 600–750 nm, its molecular formula C32F16N8Zn with central Zn promotes a short pre-irradiation time, between 1 and 5 min, to achieve the ideal CFU reduction for clinical use. Other phthalocyanines may need a pre-irradiation time of up to 60 min, the shortened PC time is due to their physical properties which are improved by the presence of their aromatic structure and their greater physical and chemical stability caused by the reduced side effects. The ability to generate cytotoxic ROS enables the use of PC in aPDT [8].

However, phthalocyanines have low solubility in physiological media, which can be solved by incorporating them into drug delivery systems such as nanostructured lipid carriers (NLC). [9]. NLC matrix is disordered, so it has empty spaces that allow accommodating high concentrations of hydrophobic drug molecules in amorphous agglomerates [10,11]. However, NLCs are liquid fluids, which is not ideal for administration into the vagina, as they disperse rapidly, to improve their application they must be used in an efficient pharmaceutical form [6].

In this context, the use of a solid pharmaceutical form, such as vaginal rings, allows local application, avoids dose variations, and can provide a more sustained and site-specific release of the drug [6]. The production of a polymer matrix nanocomposite containing as a constituent PC-NLC dispersed in ureasil-polyether organic-inorganic hybrid materials (UPEO) is an innovative alternative for the formation of the vaginal ring since this formulation has never been used before [12,13].

UPEO does not interfere with the physicochemical characteristics of the substances that will be incorporated, which allows them to be used in the development of new systems with wide-ranging applications, including controlled drug delivery. The organic phase provides physicochemical properties such as optical, electrical, and reactivity, and the inorganic phase improves thermal properties, and mechanical resistance, among others. In addition to flexibility in varying the shape and size of the final presentation [[14], [15], [16]].

These properties are attractive for application to mucous membranes, such as the vulvovaginal mucosa, as they optimize the contact time of the formulation with the region and the sustained release capacity of the drug [17]. Therefore, it is suggested that the vaginal ring PC-NLC-UPEO associated with light may offer a promising and unprecedented nanobiotechnological tool for treating VVC.