###### Abstract  
Electrospun polycaprolactone nanofibers with embedded magnetic nanoparticles were developed for use in the topical delivery of antisporiatic drugs. To test a hydrophobic drug, a tazarotene has been used, which is an efficient retinoid derivative. Such a smart hyperthermia nanofiber system with self-generated heat from the incorporated magnetic nanoparticles induced drug release in response to on-off switching of alternating magnetic fields for the delivery of tazarotene through the skin, as quantified using Franz cells. This highly efficient external field-controllable system with minimal skin irritation could create a new avenue for the topical therapy of psoriasis. sporiasis; tazarotene; topical application; drug delivery systems; nanofiber patch; magnetic nanoparticles; programmed drug release +
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unstable and more difficult to manage. Other widely used topical antisporiatic drugs include anthralin, coal tar, analogues of D3 vitamin, and retinoids. Local retinoids react with the nuclear receptors of cells and affect the transcription of genes. They have antiphlogistic, immunomodulatory, antiproliferative, and differentiating effects on keratinocytes, lymphocytes, and sebocytes [1]. the most popular topical therapy is tazarotene [2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17], which, chemically, is ethyl-[2-(4,4-dimethylthiochroman-6-yl)-ethynyl] nicotinate. Tazarotene is in organism rapidly hydrolys by esterases to a biologically active form--tazarotenic acid 6-[2-(4,4-dimethylthiochroman-6-yl)ethynyl] nicotinic acid (Figure 1). Tazarotene is a retinoic-acid-specific receptor such as RAR\(\beta\) and RAR\(\gamma\), downregulating markers of keratinocyte differentiation and proliferation, as well as inflammation. The drug also upregulates three genes, TIG-1 (tazarotene-induced gene-1), TIG-2, and TIG-3, which can mediate antiproliferative activity. For therapeutic purposes, several formulations (gel, cream, aerosol, and foam) of tazarotene are commonly used. As has been found recently, the most useful forms are microemulsions containing surfactant, as they display suitable skin permeation rates and skin uptake, which are appreciated in dermatology due to their transparency, stability, and minimal energy consumption and simplicity of preparation due to their spontaneous formation when oil, water, and surfactant are mixed together [18; 19]. Nanotechnology, although only recently emerged, has already provided considerable opportunities to address the limitations of traditional drug delivery systems' mechanisms, as well as with regard to biotechnology, biomedicine, and other fields. Nanocarriers with the appropriate characteristics can effectively target and release drugs, including retinoids, at the desired location [20]. Recently, we developed a smart hyperthermia nanofiber system with self-generated heat from the incorporated magnetic nanoparticles, which induced drug release in response to on-off switching of alternating magnetic fields for the delivery of water soluble antisporiatics, e.g., methotrexate [21]. An electrospinning method was employed to fabricate the mesh. The treatment of psoriasis is usually prolonged (weeks or months) and may lead to adverse reactions such as pruritus, burning, and erythema. Low solubility limits tazarotene incorporation into drug carriers and often results in poor compliance in patients. Therefore, we investigated the possibility of a dressing for topical application prepared via the electrospinning of nanofibers. This dressing has the desired skin targeting properties that may reduce the occurrence of adverse reactions and biomimetic scaffolds that mimic the natural hierarchical structure of tissues, which may be used for a prolonged time, as has been already shown through the use of tretinoin-loaded polycaprolactone  
Figure 1: Structure of the tazarotene and its main degradation product, tazarotenic acid.