Micro- and nanomaterials for drug delivery in skin diseases

Abstract

anostructured supramolecular hydrogels and gold nanoparticles, as two kinds of nanomaterials, were synthsized, characterized and evaluated for their potential as drug delivery systems. Two bis-imidazolium cationic surfactants (1·2Br and 2·2Br) were used as low molecular weight gelators that can incorporate anionic neutral and cationic drugs which can be used in the treatment of skin diseases such as Rosacea and Psoriasis. With either gelator and drug, optimum conditions for gel formation were found to be 5 mg/mL concentration of gelator, 50:50 ethanol:water proportion, and room temperature. 2·2Br forms a gel in 90 min while 1·2Br does it in 10 min. 1·2Br and 2·2Br gels can be formed in presence of anionic drugs sodium ibuprofen and indomethacin while 1·2Br gels can also be formed with other anionic, neutral, and cationic drugs such as sodium methotrexate, triamcinolone acetonide, betamethasone 17-valerate, tacrolimus brimonidine tartrate, AEBSF·HCl, and gemcitabine hydrochloride. The type and concentration of drug widely influence the gelling times, rheological behavior, and microscopic morphology of the gel. All formed gels are stable at room temperature for at least six months. Gels from both gelators can incorporate the drug not only at the intersticial space of the gel but also within the fibers. Gels of 1·2Br incorporate not only anionic drugs but also neutral and even cationic drugs, proving that the electrostatic atraction between the cationic gelator and a drug is not the main force driving this fiber-incorporation. The fiber-incorporation of AEBSF·HCl and further release to the intersticial space results in remarkable fiber twisting and subsequent coiling, being the first time a morphological change in supramolecular structures as a result of the exit of a guest substance (drug) has been reported. Suitable drug release from the gel matrix is observed from either gel. Gels of 1·2Br permit the release of up to ten-times more drug from the matrix than the commercial products studied. Application of gels on human skin permit a suitable permeation of drug, except for gels with tacrolimus and gemcitabine hydrochloride due to the drug physicochemical properties. The application of gel with sodium methotrexate does not involve systemic toxicity. The gels promote the retention of either drug beneath the skin, more than the commercial products studied. Gels of 2·2Br incorporating NSAID effectively inhibited inflammation in mice ears in vivo, with no significant differences as compared to gels of 1·2Br. A fast and reliable in vivo model of Rosacea was developed in rabbits. Gels of 1·2Br with triamcinolone acetonide and especially with brimonidine tartrate showed effective in vivo vasoconstrictive and anti-erythema activity using this model, being gel with brimonidine tartrate faster than the commercial Mirvaso®. Gold nanoparticles (GNP) for the treatment of Rosacea were designed and synthesized using thiolated PEG molecules of sufficient length with a mixture of hydroxyl and carboxyl groups on their surface (GNP.OH/COOH). GNP were further functionalized through their carboxylic acid group with the serine protease inhibitor AEBSF·HCl (covalently or ionically), the anti-KLK5 antibody (covalently), or the α-adrenergic agonist brimonidine tartrate (ionically). All synthesized and functionalized GNP were highly soluble in water. GNP are monodisperse in solution, comprised of a gold core of a ca. 1.5 nm diameter, and hydrodynamic diameters of around 10 nm. GNP.OH/COOH showed a high in vitro Kallikrein-5 (KLK5) inhibition comparable to AEBSF·HCl alone and to other particles. The highest inhibitions were reached by electrostatically AEBSF functionalized nanoparticles (GNP.COOH AEBSF) and by anti-KLK5 antibody-functionalized particles (GNP.antiKLK5). Fluorophore-labelled GNP.OH/COOH can be internalized in HaCaT human keratinocytes. The majority of GNP present no toxicity in keratinocytes at the concentrations tested (including KLK5-inhibiting concentrations) with viabilities around 75%. The ionic, and especially, the covalent bond of AEBSF importantly increase cell viabilities as compared to the drug alone. An in vitro model of Rosacea was developed by stimulating TLR-2 ligands in keratinocytes, which increases their intracellular KLK5 activity and increases IL-8 secretion, also confirming the biochemical pathway of Rosacea. GNP.OH/COOH, and especially GNP.AEBSF and GNP.antiKLK5 significantly reduce intracellular KLK5 in keratinocytes, which is related to their effective decrease in IL-8 secretion, for which they seem to be most promising option for becoming a new therapeutic strategy in the treatment of Rosacea.

Geles supramoleculares nanoestructurados y nanopartículas de oro, como dos tipos de nanomateriales, fueron sintetizados, caracterizados y evaluados como posibles sistemas de drug delivery. Dos tensioactivos catiónicos derivados de bis-imidazolio (1·2Br y 2·2Br) se usaron como gelificantes de bajo peso molecular para incorporar fármacos aniónicos, neutros y catiónicos, que pueden usarse en el tratamiento de enfermedades inflamatorias de la piel como Rosácea y Psoriasis. Con cada gelificante y fármaco se encontraron las condiciones óptimas de gelificación. Geles de 1·2Br and 2·2Br pueden ser formados en presencia de fármacos aniónicos ibuprofenato de sodio e indometacina, mientras que que geles de 1·2Br también se forman con otros fármacos aniónicos, neutros y catiónicos como metrotrexato de sodio, triamcinolona acetónido, betametasona 17-valerato, tacrolimus, brimonidina tartrato, AEBSF·HCl, y gemcitabina hidrocloruro. El tipo y concentración de fármaco influencia el tiempo de gelificación, comportamiento reológico y la morfología microscópica del gel. Todos los geles son estables a temperatura ambiente por lo menos seis meses. Los geles incorporan fármacos aniónicos, neutros y catiónicos, no sólo en el espacio intersticial sino también dentro de las propias fibras. La incorporación de AEBSF·HCl dentro de las fibras y su posterior liberación propicia un importante trenzado y y posterior enrollamiento de las fibras, siendo la primera vez que se observa un cambio morfológico en un material supramolecular debido a la salida de una sustancia huésped. Los geles permiten la liberación de hasta diez veces más fármaco que los productos comerciales estudiados, y permiten una mejor permeación y retención del fármaco en la piel humana que los productos comerciales. Se desarrolló un nuevo modelo in vivo de Rosácea en conejos. Geles con triamcinolona acetónido y brimonidina tartrato mostraron vasoconstricción y reducción del eritema, este último siendo más rápido que el gel Mirvaso®. Nanopartículas de oro (GNP) altamente solubles en agua fueron diseñadas para el tratamiento de la Rosácea y sintetizadas usando moléculas de PEG tioladas, con una mezcla de grupos hidroxilo y carboxilo en la superficie (GNP.OH/COOH). Las GNP se funcionalizaron con el inhibidor de serina proteasa AEBSF·HCl, el anticuerpo anti-KLK5, o brimonidina tartrato. Las partículas se forman de un núcleo de oro de cerca de 1.5 nm de diámetro y un radio hidrodinámico de 10 nm. Las GNP inhiben la actividad de la Kallikrein-5 (KLK5) in vitro, pueden internalizarse en keratinocitos HaCaT (marcadas con fluoróforo), y la mayoría no presentan citotoxicidad a las concentraciones inhibitorias. La unión del AEBSF a las GNP reduce la citotoxicidad del fármaco. Se desarrolló un nuevo modelo in vitro de Rosácea en keratinocitos, en el cual las GNP.OH/COOH y, especialmente partículas con AEBSF y con anticuerpo reducen significativamente la actividad de KLK5 intracelular y la secreción de IL-8, mostrándose como promesas en el tratamiento de la Rosácea y convirtiéndose, en tal caso, en una nueva estrategia terapéutica.