Using quality by design on optimized on hydrogel semi-solid sheet masks for enhanced skin barrier: in vitro and in vivo studies
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Presented by: Angélica Graça
Introduction: Since the start of the COVID-19 pandemic, the general population have complained about skin outbursts on the facial area due to the aggressive environment caused by wearing a mask. The pressure, friction, increase of humidity and temperature compromises the skin barrier by disrupting the structure of the stratum corneum, inducing skin lesions. The current study aims to developed and test the efficacy of low-cost and easy to produce an hydrogel sheet-mask to place between the mask and the facial area where pressure is more concentrated and suffers repeated rubbing, such as the upper edge of the nose bridge and cheekbones. This polymeric film-forming system aims to prevent skin injuries through redistribution and reduction of the pressure and also avoiding the friction triggered by mask displacement.
Materials and methods: The development of the hydrogel sheet-mask was performed using Design of Experiment (DoE) with a Quality by Design approach (QbD). The polymeric film-forming system is a gelatin-based hydrogel, a low-cost and excellent film-forming ingredient resulting in a very attractive biopolymer for application in the cosmetic industry. Biodegradable ingredients polyvinyl alcohol, silica, betaine and glycerin were added to the formulation to enhance physical properties. In vitro studies were performed to study the adaptability of the polymeric film-forming system when subjected to conditions provided by the mask use, namely compression, adhesive and tribology studies. Kinexus Lab+ Rheometer (Malvern, UK) was used with a target force of 0.5N and 1.5N to simulate the pressure exerted by surgical and N95 mask, respectively. Compression and adhesive tests were performed simultaneously using a plate-on-plate geometry at a target 1 mm/s velocity to evaluate and infer the elasticity and adhesiveness. To comprehend the lubricant properties, a constant force was exerted at different velocities using a three-ball-on-plate tribometer and two conditions were tested: the presence or not of sweat and temperatures (25ºC and 32ºC).
Ongoing biometric in vivo studies are being performed to access the efficacy of the the hydrogel sheet-mask when used underneath a FFP2 mask during 4 hours (measurements performed only with mask was used as control). Measurements were performed on the facial area. To infer the pressure relief due to pressure distribution provided by the hydrogel sheet-mask the assessment of red spots was performed by VISIA-CA™ imaging system. Skin water content was obtained using a MoistureMap system, the facial skin temperature was assessed by a thermographic camera (Flir E50bx®), measurements of the skin hydration was obtained with a Corneometer® (Dual-Cutometer MPA 580®), and the trans-epidermal water loss (TEWL) was measured using a Vapometer®.
Results: DoE and QbD tools were useful to optimize the formula and the manufacturing process for an easier, economical and reproducible scale-up process. Compression test demonstrated that the polymeric film-forming system presents complete elastic recovery with an adhesiveness of 0.24 ± 0.03 N, more adhesive than a film with gelatin alone (0.10 ± 0.03 N). Tribology assay has demonstrated the integrity of the hydrogel sheet-mask throughout the assay with similar friction values for both temperatures and a slight decrease in values when sweat was added (average of 1.1x10-2±4.3x10-4 N.m at 0.5N and 2.0x10-2±2.8x10-3 N.m at 1.5N without sweat and 1.0x10-2±9.9x10-5 N.m at 0.5N and 1.6x10-2±8.0x10-4 N.m at 1.5N with sweat). Regarding the biometric in vivo methodology, the tests performed so far, indicated a statistical difference in skin hydration which increased with the use of hydrogel sheet-mask underneath the mask.
Conclusion: In conclusion, the developed semi-solid hydrogel sheet-mask presents promising characteristics for a skincare mask to reenforce the skin barrier to use underneath the mask. The resistant physical properties of this hydrogel sheet-mask and attenuation the physiological alterations in the facial area during its use are good indicatives that this cosmetic can prevent skin lesions and promote a healthier skin during pandemic times.
Materials and methods: The development of the hydrogel sheet-mask was performed using Design of Experiment (DoE) with a Quality by Design approach (QbD). The polymeric film-forming system is a gelatin-based hydrogel, a low-cost and excellent film-forming ingredient resulting in a very attractive biopolymer for application in the cosmetic industry. Biodegradable ingredients polyvinyl alcohol, silica, betaine and glycerin were added to the formulation to enhance physical properties. In vitro studies were performed to study the adaptability of the polymeric film-forming system when subjected to conditions provided by the mask use, namely compression, adhesive and tribology studies. Kinexus Lab+ Rheometer (Malvern, UK) was used with a target force of 0.5N and 1.5N to simulate the pressure exerted by surgical and N95 mask, respectively. Compression and adhesive tests were performed simultaneously using a plate-on-plate geometry at a target 1 mm/s velocity to evaluate and infer the elasticity and adhesiveness. To comprehend the lubricant properties, a constant force was exerted at different velocities using a three-ball-on-plate tribometer and two conditions were tested: the presence or not of sweat and temperatures (25ºC and 32ºC).
Ongoing biometric in vivo studies are being performed to access the efficacy of the the hydrogel sheet-mask when used underneath a FFP2 mask during 4 hours (measurements performed only with mask was used as control). Measurements were performed on the facial area. To infer the pressure relief due to pressure distribution provided by the hydrogel sheet-mask the assessment of red spots was performed by VISIA-CA™ imaging system. Skin water content was obtained using a MoistureMap system, the facial skin temperature was assessed by a thermographic camera (Flir E50bx®), measurements of the skin hydration was obtained with a Corneometer® (Dual-Cutometer MPA 580®), and the trans-epidermal water loss (TEWL) was measured using a Vapometer®.
Results: DoE and QbD tools were useful to optimize the formula and the manufacturing process for an easier, economical and reproducible scale-up process. Compression test demonstrated that the polymeric film-forming system presents complete elastic recovery with an adhesiveness of 0.24 ± 0.03 N, more adhesive than a film with gelatin alone (0.10 ± 0.03 N). Tribology assay has demonstrated the integrity of the hydrogel sheet-mask throughout the assay with similar friction values for both temperatures and a slight decrease in values when sweat was added (average of 1.1x10-2±4.3x10-4 N.m at 0.5N and 2.0x10-2±2.8x10-3 N.m at 1.5N without sweat and 1.0x10-2±9.9x10-5 N.m at 0.5N and 1.6x10-2±8.0x10-4 N.m at 1.5N with sweat). Regarding the biometric in vivo methodology, the tests performed so far, indicated a statistical difference in skin hydration which increased with the use of hydrogel sheet-mask underneath the mask.
Conclusion: In conclusion, the developed semi-solid hydrogel sheet-mask presents promising characteristics for a skincare mask to reenforce the skin barrier to use underneath the mask. The resistant physical properties of this hydrogel sheet-mask and attenuation the physiological alterations in the facial area during its use are good indicatives that this cosmetic can prevent skin lesions and promote a healthier skin during pandemic times.