# Quality by design optimization of microemulsions for topical delivery of Passiflora setacea seed oil

## TL;DR

This study develops a stable topical gel using nanotechnology to deliver Passiflora setacea seed oil, improving its usability for skin applications.

## Contribution

A quality by design approach was used to optimize a microemulsion-based delivery system for P. setacea seed oil.

## Key findings

- The optimized microemulsion had a hydrodynamic diameter of ~22 nm and remained stable for 60 days.
- The formulation showed high cell viability in macrophages and endothelial cells at low concentrations.
- The gel formulation incorporated antioxidants and preservatives to enhance stability and safety.

## Abstract

Passiflora setacea seed oil is a natural source of bioactive unsaturated fatty acids, notably linoleic acid (ω-6) and oleic acid (ω-9), with promising antioxidant and anti-inflammatory potential for dermatological applications. However, its direct use is limited by poor physicochemical and organoleptic properties. This study aimed to develop and optimize a topical microemulsion (ME) system incorporating P. setacea seed oil using quality by design principles to address formulation challenges. The oil was extracted via Soxhlet and characterized by gas chromatography–mass spectrometry and thermal analysis. A full factorial design, followed by a Box–Behnken design, was employed to optimize the formulation based on critical quality attributes and the defined quality target product profile. The optimized ME presented a hydrodynamic diameter of approximately 22 nm and polydispersity index below 0.2 and remained stable for 60 days. The ME was gelled with sodium carboxymethyl cellulose, while vitamin E and Liquid Germall® Plus were incorporated as antioxidant and preservative agents, respectively, yielding the final topical gel formulation. Cytocompatibility assays demonstrated high cell viability for ME at concentrations below 2 mg/mL in RAW 264.7 macrophages and 0.5 mg/mL in human umbilical vein endothelial cells. Overall, this work presents a promising nanotechnology-based topical delivery platform for P. setacea seed oil, employing quality by design principles to ensure formulation performance, stability, and skin cell compatibility.