Potential of porous silicon nanoparticles as an emerging platform for cancer theranostics.

Currently, nanoscience is a major part of biomedical research, due to material advances that aid the development of new tools and techniques to replace traditional methods. To this end, the potential of porous silicon nanoparticles (pSiNPs) has been examined, especially in areas of cancer treatment and diagnosis. The properties of pSiNPs such as their porous structure, high surface area and porous volume, biocompatibility and biodegradability offer real opportunities for focal therapies that can avoid the side effects caused by conventional methods. This review is focused on pSiNPs and their potential application in targeted anticancer drug delivery, and photodynamic and thermal therapies. In addition, the luminescence properties of pSiNPS are useful in bioimaging and diagnosis. Hence, the theranostic potential of pSiNPs is discussed herein.

Thick collagen-based 3D matrices including growth factors to induce neurite outgrowth.

Designing synthetic microenvironments for cellular investigations is a very active area of research at the crossroads of cell biology and materials science. The present work describes the design and functionalization of a three-dimensional (3D) culture support dedicated to the study of neurite outgrowth from neural cells. It is based on a dense self-assembled collagen matrix stabilized by 100-nm-wide interconnected native fibrils without chemical crosslinking. The matrices were made suitable for cell manipulation and direct observation in confocal microscopy by anchoring them to traditional glass supports with a calibrated thickness of ∼50µm. The matrix composition can be readily adapted to specific neural cell types, notably by incorporating appropriate neurotrophic growth factors. Both PC-12 and SH-SY5Y lines respond to growth factors (nerve growth factor and brain-derived neurotrophic factor, respectively) impregnated and slowly released from the support. Significant neurite outgrowth is reported for a large proportion of cells, up to 66% for PC12 and 49% for SH-SY5Y. It is also shown that both growth factors can be chemically conjugated (EDC/NHS) throughout the matrix and yield similar proportions of cells with longer neurites (61% and 52%, respectively). Finally, neurite outgrowth was observed over several tens of microns within the 3D matrix, with both diffusing and immobilized growth factors.

Human dental pulp stem cells growth and osteodifferentiation on porous resorbable scaffolds.

Short Communication selected from the Oral Presentations of the 56th Congress of the Groupèment International pour la Recherche Scientifique en Stomatologie et Odontologie, Peñafiel (Portugal) May 2012.

Intravitreal properties of porous silicon photonic crystals: a potential self-reporting intraocular drug-delivery vehicle.

AIM: To determine the suitability of porous silicon photonic crystals for intraocular drug-delivery. METHODS: A rugate structure was electrochemically etched into a highly doped p-type silicon substrate to create a porous silicon film that was subsequently removed and ultrasonically fractured into particles. To stabilise the particles in aqueous media, the silicon particles were modified by surface alkylation (using thermal hydrosilylation) or by thermal oxidation. Unmodified particles, hydrosilylated particles and oxidised particles were injected into rabbit vitreous. The stability and toxicity of each type of particle were studied by indirect ophthalmoscopy, biomicroscopy, tonometry, electroretinography (ERG) and histology. RESULTS: No toxicity was observed with any type of the particles during a period of >4 months. Surface alkylation led to dramatically increased intravitreal stability and slow degradation. The estimated vitreous half-life increased from 1 week (fresh particles) to 5 weeks (oxidised particles) and to 16 weeks (hydrosilylated particles). CONCLUSION: The porous silicon photonic crystals showed good biocompatibility and may be used as an intraocular drug-delivery system. The intravitreal injectable porous silicon photonic crystals may be engineered to host a variety of therapeutics and achieve controlled drug release over long periods of time to treat chronic vitreoretinal diseases.