# Grape By-Products in Sustainable Cosmetics: Nanoencapsulation and Market Trends
## 6 Nanoencapsulation Trends
### Nanoparticles  
Nanoparticles, Figure 3, are colloidal solids that can be branched or spherical in shape [97]. For instance, [PERSON] et al. [98] synthesised solid lipid nanoparticles (SLNPs), which are constituted by solid lipids and surfactants [99], made of stearic acid, poloxamer 407, soy phosphatidylcholine, and an aqueous phase, for transdermal delivery of resveratrol. These particles showed a diameter inferior to 200 nm and were more effective than kojic acid in inhibiting tyrosinase. Moreover, they showed the particles to be non-toxic in HaCat cells and allowed a resveratrol permeation through the skin up to 45% after 24 h. Furthermore, [PERSON] et al. [100] created a dual drug-loaded nanostructured lipid carrier (NLC) gel, based on a 1% binary lipid mixture (Labrafil M 2125 CS and Labrafil M 2130 CS) and an aqueous phase (5% Cremophor RH40 in distilled water), containing resveratrol and quercetin for improved disposition in dermal and epidermal layers, obtaining a resveratrol encapsulation effectiveness close to 90%. When compared to traditional gel, the NLC results showed a rise in the resveratrol maximum concentration in skin (C\({}_{\text{skin max}}\), \(\mu\)gcm\({}^{-2}\)) and in the area under the curve (AUC\({}_{0\text{-8h}}\), \(\mu\)gcm\({}^{-2}\)h) from 0 to 8 h. [PERSON] et al. [101] created novel poly(lactic-co-glycolic) acid nanoparticles, with 50 and 150 nm of diameter, to boost the antifungal efficacy of grape pomace extract against _Candida albicans_, reducing biofilm formation and maturation by 63% and 50%, respectively. Another study showed that NLCs and SLNPs are suitable carriers for the cutaneous delivery of resveratrol, providing a long-lasting antioxidant effect [102]. Very similar outcomes were reported by [PERSON] [103], where resveratrol-loaded NLCs and SLNPs, prepared with Compritol 888 ATO, Myglyol, Poloxamer188, and Tween 80, were shown to improve its antioxidant activity. In addition, ex vivo studies showed that NLCs were more effective than SNLPs for epidermal deep penetration. Furthermore, [PERSON] et al. [104] observed that the administrations of lipid nanoparticles (Nano Aging Reverse(tm); Inventiva, Brazil) carrying grape seed oil, among other antioxidants, resulted in a significant reduction in wrinkle intensity. [PERSON] et al. [105] developed lipid-core nanocapsules (LNC), made with poly(\(\varepsilon\)-caprolactone), sorbitan monostearate and grape seed oil, which improved resveratrol photostability and enhanced its skin penetration and absorption, providing a solution for continuous polyphenol administration, for application in the treatment of skin disorders, such as sunburns. Moreover, a study by [PERSON] et al. [106] showed that resveratrol-loaded SLNPs, formulated with Precirol ATO5, Tween 20, and Span 80 combined into a carbopol gel, with a mean size less than 100 nm, had an encapsulation efficiency of 68-89%. They also provided a controlled drug release up to 24 h and no skin irritation. Polysorbate 60 and poloxamer 188 are also reported as surfactants for the development of cetyl palmit- and stearic acid-based SLNPs, with encapsulation efficiency of 70% and 89%, respectively [107; 108]. The gel demonstratedcontrolled release up to 24 h without causing skin irritation. Additionally, [PERSON] and [PERSON] [109] reported that SLNPs prepared with Compritol 888 ATO, Phospholipon 80H, and Poloxamer 188, of less than 180 nm, can go through keratinocytes membranes without causing significant alterations in cell morphology and function. [PERSON] et al. [110] developed sericin protein-based nanoparticles, which encapsulated resveratrol with a 71-75% efficacy, proving to be non-cytotoxic for dermal fibroblasts, and allowing a continuous drug release for 72 h.