Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disorder characterized by intense itching and recurrent eczematous lesions. Topical corticosteroids are the firstline treatment to control moderate-to-severe AD; however, prolonged application of corticosteroids is required, which can result in dermal atrophy as a side effect. Drug-delivery systems can provide more effective and targeted therapy strategies. In this study, budesonide (BUD) was encapsulated into chitosan (CS)coated PLGA nanoparticles, which were further incorporated into poloxamer hydrogels to improve the anti-inflammatory activity and decrease adverse effects. The nanoparticles were prepared by the emulsification−solvent evaporation technique, and their physicochemical characteristics were evaluated. Rheological properties of the hydrogels, such as viscosity and sol−gel transition temperature, were evaluated with and without nanoparticles. In vitro release kinetics and ex vivo drug absorption studies were performed using Franz diffusion cells. The nanoparticles showed a mean diameter of 324 ± 4 nm, positive ζ potential (20 mV) due to CS coating, and high encapsulation efficiency (>90%). The nanoparticles did not show cytotoxic effects in primary human fibroblasts and keratinocytes; however, all formulations induced the generation of reactive oxygen species. Both nanoparticles and hydrogels were able to change the release kinetics of BUD when compared to the nonencapsulated compound. Nanoparticles were not able to surmount the stratum corneum of excised human skin, but the nanoencapsulation facilitated the skin absorption of BUD. The hydrogels containing nanoparticles or not showed non-Newtonian and pseudoplastic behavior. The nanoformulations seem to be a good candidate to deliver glucocorticoids in the skin of AD patients.

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Topical delivery of local anesthetics (LAs) is commonly used to decrease painful sensations, block pain throughout procedures, and alleviate pain after surgery. Dermal and/or transdermal delivery of LAs has other advantages, such as sustained drug delivery and decreased systemic adverse effects. This study reports the development of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles coated with chitosan for the sustained release and topicality of benzocaine (BZC) and topical delivery. BZC PLGA nanoparticles or nonencapsulated drugs were further incorporated into Poloxamer hydrogels (Pluronic™ F-127). The nanoparticles showed a mean diameter of 380 ± 4  nm, positive zeta potential after coating with chitosan ( 23.3 ± 1.7  mV), and high encapsulation efficiency ( 96.7 ± 0.02 % ). Cellular viability greater than 70% for both fibroblasts and keratinocytes was observed after treatment with nanoparticles, which is in accordance with the preconized guidelines for biomedical devices and delivery systems. Both the nanoparticles and hydrogels were able to modulate BZC delivery and increase drug permeation when compared to the nonencapsulated drug. Furthermore, the incorporation of limonene into hydrogels containing BZC-loaded nanoparticles increased the BZC permeation rates. Non-Newtonian and pseudoplastic behaviors were observed for all hydrogel nanoformulations with or without nanoparticles. These results demonstrate that the hydrogel-nanoparticle hybrids could be a promising delivery system for prolonged local anesthetic therapy.

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The most important arboviruses are those that cause dengue, yellow fever, chikungunya, and Zika, for which the main vector is the Aedes aegypti mosquito. The use of repellents is an important way to combat mosquito-borne pathogens. In this work, a safe method of protection employing a repellent was developed based on a slow release system composed of zein nanoparticles containing the active agents icaridin and geraniol incorporated in a cellulose gel matrix. Analyses were performed to characterize the nanoparticles and the gel formulation. The nanoparticles containing the repellents presented a hydrodynamic diameter of 229 ± 9 nm, polydispersity index of 0.38 ± 0.10, and zeta potential of +29.4 ± 0.8 mV. The efficiencies of encapsulation in the zein nanoparticles exceeded 85% for icaridin and 98% for geraniol. Rheological characterization of the gels containing nanoparticles and repellents showed that the viscoelastic characteristic of hydroxypropylmethylcellulose gel was preserved. Release tests demonstrated that the use of nanoparticles in combination with the gel matrix led to improved performance of the formulations. Atomic force microscopy analyses enabled visualization of the gel network containing the nanoparticles. Cytotoxicity assays using 3T3 and HaCaT cell cultures showed low toxicity profiles for the active agents and the nanoparticles. The results demonstrated the potential of these repellent systems to provide prolonged protection while decreasing toxicity.