Zn/Al Layered double hydroxides nanostructure as effective controlled release vehicle of nicotinic acid for topical applications

Abstract

The delivery of active ingredients through the human skin is an arduous exercise because of its structural intricacy and outstanding barrier characteristics. Nanotechnological developments have produced advanced delivery systems based on nanomaterials to reinforce the skin's ability to absorb hydrophobic, hydrophilic active ingredients and macromolecules. In this study, inorganic crystalline layered double hydroxides nanostructures (LDH) were used as an advanced release system for nicotinic acid, with skin lightening properties. Nicotinic acid was incorporated into the interlayer space of Zn/Al LDH, by co-precipitation method to develop LDH hybrids. The LDH hybrids were characterized using FTIR, XRD, TGA, and SEM. Intercalation of nicotinic acid in the interlayer space of Zn/Al LDH was ascertained by the shifting of the basal spacing d (003) reflection in the XRD pattern, to lower angles (2θ). FTIR spectra of the Zn/Al LDH hybrids displayed the absorption frequencies of nicotinic acid that indicated the presence of nicotinic acid within the LDH matrix. TGA showed that nicotinic acid intercalated in the interlayer of LDH exhibited better thermal stability than the free form of nicotinic acid. In vitro release experiments revealed controlled and pH-responsive release of nicotinic acid from Zn/Al LDH. Transdermal permeation studies employing Franz- diffusion cells demonstrated that the formulation containing nicotinic acid-intercalated Zn/Al LDH considerably enhanced the penetration of nicotinic acid compared to the formulation containing the free form of nicotinic acid. Thus, Zn/Al LDH has great potential for use as a sustained and controlled release reservoir of nicotinic acid in skin care and other topical applications.