1. Introduction 2. NanoPS: a versatile material 3. NanoPS in drug-delivery systems 4. Expert opinion Review Nanostructured porous silicon-mediated drug delivery Ra ul J Martı ´n-Palma † , Jacobo Herna ´ndez-Montelongo, Vicente Torres-Costa, Miguel Manso-Silva ´n & A ´ lvaro Mun ˜oz-Noval † Universidad Auto´noma de Madrid, Departamento de Fı´sica Aplicada, Campus de Cantoblanco, Madrid, Spain Introduction: The particular properties of nanostructured porous silicon (nanoPS) make it an attractive material for controlled and localized release of therapeutics within the body, aiming at increased efficacy and reduced risks of potential side effects. Since this is a rapidly evolving field as a conse- quence of the number of research groups involved, a critical review of the state of the art is necessary. Areas covered: In this work, the most promising and successful applications of nanoPS in the field of drug delivery are reviewed and discussed. Two key issues such as drug loading and release are also analyzed in detail. The development of multifunctional (hybrid) systems, aiming at imparting additional functionalities to the nanoPS particles such as luminescence, magnetic response and/or plasmonic effects (allowing simultaneous tracking and guiding), is also examined. Expert opinion: Nanostructured materials based on silicon are promising platforms for pharmaceutical applications given their ability to degrade and low toxicity. However, a very limited number of clinical applications have been demonstrated so far. Keywords: composite, drug delivery, hybrid system, magnetic release, nanostructure, photoluminescence, porous silicon Expert Opin. Drug Deliv. [Early Online] 1. Introduction Nanoparticles are being increasingly considered and, in some cases, successfully used for several applications in the broad field of biomedicine, including diagnosis and therapy [1-4]. This is in part a consequence of the tremendous progress of nanotech- nologies during the last decades, which has led to the development of a vast number of techniques for the fabrication of nanometric structures with controlled size, shape and composition. This allows to accurately control their physicochemical proper- ties, thus making it possible to tailor their response. Additionally, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition [5]. Moreover, new hybrid nanostructures can be obtained for biomedical applications by binding selected biomolecules to nano- structured particles and surfaces [6]. In particular, a great deal of attention has recently been paid to nanoparticles for their use as drug-delivery systems. To this end, a number of nanocarriers including liposomes [7,8], polymeric colloids, iron oxide nanoparticles, as well as silica and alumina mesoporous nanostructures have been studied [9,10]. The discovery of photoluminescence from nanostructured porous silicon (nanoPS) in 1990 led to the development of a number of applications in the fields of electronics and photonics. However, the demonstration of biodegradability of this material in physiological environments in 1995 opened the way for its use in 10.1517/17425247.2014.919254 © 2014 Informa UK, Ltd. ISSN 1742-5247, e-ISSN 1744-7593 1 All rights reserved: reproduction in whole or in part not permitted Expert Opin. Drug Deliv. Downloaded from informahealthcare.com by UNICAMP on 06/18/14 For personal use only.