Silicified collagen materials: Modulation of the in vitro and in vivo response.

Collagen derived materials offer distinct advantages over synthetic polymers, considering their natural inherited biocompatibility and mechanical properties. However, because of the extraction procedure, the latter frequently need to be enhanced through the use of different crosslinking methods. Aldehydes are often used for the stabilization of biomaterials but the introduction of crosslinkers slightly alters the protein's surface reactivity hence calling for new biocompatibility studies. At the same time, silicate modification of natural polymers has gained interest within the biomaterials field for their strengthening potential and ease of manipulation, giving rise to different surfaces and bulk materials. In the present work, collagen gels modified with glutaraldehyde (ColGA) or glutaraldehyde and an aminosilane (ColGASi) were evaluated in vitro and in vivo with the aim to obtain biomaterials for wound dressings. The results obtained were compared to those derived from unmodified collagen matrices (Col). In vitro assays focused on the interaction of the materials with elements present in the human blood whereas in vivo assays evaluated their ability to support cell proliferation and angiogenesis for a period of 30 days in a rodent model. Col gels induced an increase in platelet aggregation while ColGA gels decreased it. On the other hand, ColGASi had no effect on platelet aggregation but induced IL-1ß and nitric oxide platelet secretion. All gels induced lower IL-6 levels in PMN cells cultures when compared to controls. Col and ColGA gels decreased IL-1ß concentration whereas ColGASi induced high expression of TGF-ß in PMN cells. All gels decreased nitric oxide secretion but Col and ColGA gels increased IL-1ß production by monocytes. Definitely, all gels induced an anti and pro-inflammatory profile depending on the cell type with which they interact. In vivo, an increased cellular infiltration was observed along with new blood vessel formation in those matrices containing silicified collagen, while glutaraldehyde fixed collagen induced a foreign body reaction and appeared surrounded by a fibrous capsule after 30 days of subcutaneous implantation. Overall, the results obtained show that the silicification of collagen has advantages not only through the enhancement of its mechanical properties but also through the stimulation of the integration of the material with the surrounding tissue.

Nanoparticles and capillary electrophoresis: A marriage with environmental impact.

The impact of nanomaterials in the environment and human health is a cause of big concern and even though intensive studies are currently being carried out, there is still a lot to elucidate. The development of validated methods for the characterization and quantification of nanomaterials and their impact on the environment should be encouraged to achieve a proper, safe, and sustainable use of nanoparticles (NPs). Recently, CE emerged as a well-adapted technique for the analysis of environmental samples. This review presents the application of NPs together with CE systems for environmental pollutants analysis, as well as the application of CE techniques for the analysis of various types of NPs.

Advances in collagen, chitosan and silica biomaterials for oral tissue regeneration: from basics to clinical trials.

Different materials have distinct surface and bulk characteristics; each of them potentially useful for the treatment of a particular wound or disease. By reviewing those materials that have reached a clinical stage the reader will have a broad panorama of the possibilities a particular material can offer, regarding its ability to support fast tissue regeneration. This review covers the most recent advances made towards the development of biomaterials aimed to support regenerative processes. Indeed, we highlight key examples, from basic research to clinical trials, of biomaterials for a specific biomedical application. In this context, the focus is made on collagen, chitosan and silica which are key representatives of a protein, a polysaccharide and an inorganic material usually employed as biomaterials. Particularly, this review article presents an overview of their potential therapeutics in the treatment of disorders within the oral mucosa and tooth supporting tissues. Finally, the importance of in vivo and in vitro studies, clinical evidence studies, systematic reviews and meta-analyses as an adequate guidance for biomaterial design and development is highlighted.

A new method for the preparation of biocompatible silica coated-collagen hydrogels.

Silica-collagen scaffolds were obtained by covalent binding of an aminosilane to glutaraldehyde fixed collagen hydrogels, rendering a three dimensional network of silicon coated collagen fibrils. When compared to non-silicified collagen, silica containing matrices exhibited a 60 fold increment in the rheological properties. Moreover, acellular degradation by collagenase type I indicated that enzymatic digestion occurred at a slower rate for silica modified hydrogels, hence enabling a controlled degradation of the obtained material. In addition, fibroblastic cells seeded on silicified collagen matrices were able to adhere, proliferate and migrate within the scaffold for over 3 weeks as shown by MTT tests and hematoxylin-eosin staining. These results suggest that the herein described method could be useful in the design of materials for tissue engineering purposes.

Recent patents on the synthesis and application of silica nanoparticles for drug delivery.

Drug delivery systems are designed to improve therapy efficacy as well as patient compliance. This could be accomplished by specifically targeting a medication intact to its active site, therefore reducing side-effects and enabling high local drug concentrations. Silica nanoparticles have gained ground in the biomedical field for their biocompatibility and biodegradability, being themselves inert and stable, thus enabling a variety of formulation designs for application in the pharmaceutical industry. This paper is a review of the recent patents on the applications of silica nanoparticles for drug delivery and their preparation. The review will focus on the different techniques available to obtain silica nanoparticles with variable morphology and their drug targeting applications, providing an overview of silica particles synthesis described in the literature.