J. Cosmet. Sci., 65, 299–314 (September/October 2014) 299 Applying the sensory analysis in the development of chitosan hydrogel containing polymeric nanocapsules for cutaneous use RENATA V. CONTRI, IRENE C. KÜLKAMP-GUERREIRO, KATHERINE KRIESER, ADRIANA R. POHLMANN, and SÍLVIA S. GUTERRES, Programa de Pós-Graduação em Ciências Farmacêuticas (R.V.C., I.C.K.-G., A.R.P., S.S.G.),Faculdade de Farmácia (K.K., I.C.K.-G., S.S.G.), and Instituto de Química (A.R.P.), Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil. Accepted for publication July 6, 2014. Synopsis This work aimed to develop a chitosan hydrogel containing polymeric nanocapsules with optimized sensory properties, linking the advantages of the nanocarriers, such as controlled release and protection of the sub- stances, to the chitosan properties, such as bioadherence, cicatrizing effect, and antimicrobial activity. Sixty untrained volunteers evaluated the sensory properties of chitosan hydrogels compared to hydroxyethyl cel- lulose gels (Phase I) and to optimized chitosan gels (Phase II). The volunteers’ preference between formula- tions was also evaluated. The chitosan hydrogel, despite the presence of nanocapsules, presented higher immediate stickiness and fi lm formation on the skin, and lower acceptance than the hydroxyethyl cellulose gels. Regarding the optimized gel, decrease on the fi lm formation and increase on the homogeneity of the fi lm was observed, compared to the prior chitosan gel. So, the optimization of the chitosan gel led to higher acceptance by the volunteers. The presence of nanocapsules, besides increasing the chitosan gel consistence, increased the perception of fi lm formation. For the optimized chitosan gel, the nanocapsules increased the homogeneity of the fi lm formed on the skin, without increasing the perception of fi lm formation. In conclu- sion, through sensory analysis, the formulation was optimized presenting, at the fi nal stage, adequate sensory properties for cutaneous use. INTRODUCTION Hydrogels are networks that retain a great amount of water while are maintained insolu- ble due to the crosslinks between the polymeric chains (1). It is a very common pharma- ceutical dosage form in dermatology and cosmetology due to its nongreasy properties. The most usual hydrogel-forming polymers are derived from the polyacrylic acid, such as the carbomers, and from cellulose, such as hydroxyethyl cellulose (2). Chitosan, gelatin, Address all correspondence to Irene Clemes Külkamp-Guerreiro at irene@ufrgs.br.

JOURNAL OF COSMETIC SCIENCE 300 and xanthan gum can be mentioned among the natural polymers used in the production of hydrogels (1). Chitosan, a cationic biopolymer, presents applications in several distinct areas, such as the biomedical, cosmetics, food technology, and pharmaceutical technology (3). The chitosan hydrogels present interesting cutaneous properties including a great bioadherence and fi lm formation (4), cicatrizing effect (5), and antimicrobial activity (6). It is also possible that these hydrogels interfere in the drug skin penetration due to the chitosan effect on the tight junctions between epithelial cells (2). The incorporation of solid lipid nanoparticles (7) and liposomes (8) in chitosan hydrogels has already been proposed, but the incorporation of polymeric nanocapsules in such hydro- gels represents an innovative proposal from our research group (9) aiming to link the advan- tages of both systems. The polymeric nanocapsules are characterized by the presence of a liquid core surrounded by a polymeric wall (10). Regarding the cutaneous use, the nanoen- capsulation of active substances can increase the drug photostability (11) and change the sensory properties (12). Besides that, the control of the drug release can prolong the action (13) and modulate the skin penetration as well (14,15). In order to facilitate the cutaneous application of aqueous nanoparticles suspensions, several studies have been devoted to the development of semisolid vehicles containing polymeric nanocapsules (16,17). The measurement and interpretation of human responses (senses) to the properties of products is called sensory analysis. It has been applied in the development of distinct products, including cosmetics (18–21). Among the different kinds of tests used in the sensory analysis, there are discriminative, descriptive, and affective tests. The discrimina- tive and affective tests, which are the focus of this work, aim to detect if there is a differ- ence between samples and which the preferred sample is, respectively (21). This work explores the sensory properties as a tool in the pharmacotechnical development of a novel chitosan hydrogel containing nanoparticles linking the advantages of the chitosan and of the nanocapsules to obtain a cutaneous formulation of high skin permanence. Despite its interesting cutaneous properties, the sensory properties of a chitosan hydrogel for cuta- neous use have never been described before, as far as it is known. Also, the infl uence of the nanocapsules to the sensory properties is of great importance, considering the great number of research papers and products in the market containing nanoparticles. The main questions to be addressed are: (i) Are there differences between the chitosan hydrogel and another hydrogel of common cosmetic use (hydroxyethyl cellulose) regarding the sensory proper- ties? (ii) How is it possible, by means of the pharmacotechnical development, to improve the sensory acceptance of the chitosan hydrogel? (iii) Does the presence of nanocapsules in- terfere in the sensory properties of the chitosan hydrogels? The infl uence of the chitosan gel and of the polymeric nanocapsules on the sensory properties may impact the future develop- ment of dermal formulations based on chitosan and/or nanoparticles. EXPERIMENTAL MATERIALS The hydrophilic surfactant polisorbate 80 was purchased from Labsynth (São Paulo, Brazil) and the capric/caprylic tryglicerides, used as nanocapsule core, was obtained from Brasquim (Porto Alegre, Brazil). EudragitRS 100®, used to form the nanoparticle shell,