Design and Characterization of a New Quercus Suber-Based Pickering Emulsion for Topical Application

Abstract

Quercus Suber Bark from Quercus suber L. is a natural, renewable and biodegradable biomaterial with multifunctional proprieties. In this study, we used it as solid particles to stabilize a Pickering emulsion. The main goal was to produce an optimized topical formulation using biocompatible organic particles as stabilizers of the emulsion instead of the common surfactants, whilst benefiting from Quercus suber L. proprieties. In this work, a Quality by Design (QbD) approach was successfully applied to the production of this emulsion. A screening design was conducted, identifying the critical variables of the formula and process, affecting the critical quality attributes of the emulsion (droplet size distribution). The optimization of the production was made through the establishment of the design space. The stability was also investigated during 30 days, demonstrating that Quercus Suber Bark-stabilized emulsions are stable since the droplet size distribution lowers. In vitro studies were performed to assess antioxidant and antiaging efficacy, which revealed that the formulation had indeed antioxidant proprieties. A physicochemical characterization demonstrated that the formulation presents a shear-thinning fluid, ideal for topical administration. The in vivo compatibility study confirmed that the final formulation is not skin irritant, being safe for human use. A sensorial analysis was also performed, using a simple sensory questionnaire, revealing very positive results. Thus, the use of Quercus Suber Bark particles as a multifunctional solid ingredient contributed to achieve a stable, effective and innovative Pickering emulsion with a meaningful synergistic protection against oxidative stress.

Progressing Towards the Sustainable Development of Cream Formulations

“…A general trend is observed among Herschel-Bulkley, Bingham and Casson models exhibiting superior τ0 values for the more viscous systems. administration [68]. A direct relationship between the τ0 and the n index can be also inferred.…”

“…Pharmaceutics 2020, 12, x FOR PEER REVIEW quantitatively describe the shear flow behavior of different materials, in pharmaceutical products [4]. Accordingly, reaching τ0, the formulation initiates exceeded, while increasing the shear rate, a decrease in formulation viscosity is o Herschel-Bulkley model, DoE formulations with higher η10 tend towards a shear t (n > 1), while formulations with lower η10 exhibit shear thinning properties (n < 1) administration [68]. A direct relationship between the τ0 and the n index can be a In the Cross model, superior viscosity values were denoted when the shear In contrast, when the shear rate tends towards infinite values, a decrease in sa observed.…”

“…Accordingly, reaching τ 0 , the formulation initiates the flow and, once exceeded, while increasing the shear rate, a decrease in formulation viscosity is observed [67]. In the Herschel-Bulkley model, DoE formulations with higher η 10 tend towards a shear thickening behavior (n > 1), while formulations with lower η 10 exhibit shear thinning properties (n < 1), suitable for topical administration [68]. A direct relationship between the τ 0 and the n index can be also inferred.…”

Pickering Emulsions Stabilized by Calcium Carbonate Particles: A New Topical Formulation

“…The particle size distribution was determined using a Malvern Mastersizer 2000 (Malvern Instruments, Malvern, UK), coupled with a Hydro S accessory, with a default refractive index of 1.52, as described previously. The span was also calculated as described [24].…”

“…To investigate the variables affecting the responses, a central composite design composed of five levels (coded as −α, −1, 0, 1, and +α) was used, as described in our previous work (Table S1, Supplementary Materials) [24]. The software MODDE®Pro 11 (Umetrics, Umeå, Sweden) was used for data analysis, and results were considered statistically significant for p < 0.05.…”