LUMINESCENT POROUS SILICON FOR NANOTHERANOSTICS

A variety of materials have been used in the treatment of disease or injury. A common definition of a ‘biomaterial’ or ‘biomedical material’ is a synthetic non-living material that replaces part of a living system or functions in intimate contact with living tissue. Humans have been using natural materials in medicine for hundreds of years. Some of the oldest examples include the use of linen for sutures, wood to replace teeth and the glass eye. At the moment, the semiconductor Si would seem ideally placed to become a core biomaterial in such a biomaterial trend for two main reasons. First, developments in nanotechnology allow the manufacture of precisely structure of Si to obtain photoluminescent (PL) properties in the visible range at room temperature. Second, recent research has shown that Si itself can be made into much more biocompatible forms than previously imagined: it has the potential to chemically bond directly to living tissue, and even be fully biodegradable. This dissertation presents the development of Si materials for imaging and biomedical treatments. After a brief introduction to nanotheranostics and the biomedical applications of Si in Chapter I, Chapter II presents experimental data of making light emitting porous Si (pSi). Then, Chapters II-V are related to surface stabilization of the pSi. Organic functionalizations have been utilized to stabilize PL properties in atmospheric condition. These modifications with related characterizations demonstrate in Chapter III. Further modifications for long-term optical stability in biological conditions have been reported in Chapter IV. The other approach of surface modification of Si is thermal oxidation as an effective way to passivate its surface. Chapter V demonstrates experimental and analytical results concerning kinetics of thermal oxidation reaction of pSi. As for application of the pSi, Chapters VI and VII report results of interaction with cells and drugs, respectively, in in vitro conditions. In the Chapter VI, pSi incubated with human dendritic cells to check toxicity and immune response. In addition, bioimaging properties of luminescent pSi monitored by a conventional confocal microscopy inside the cells and with two photon absorption microscopy. On the other side, the main challenge for usage of pSi in drug delivery is the redox activity of pSi on drugs. In Chapter VII this phenomenon was investigated comprehensively combine with loading capacity and release profile. Indeed, Nanotheranostics is a big challenging topic in the field of bionanotechnology. Owing to the fact that it needs a biocompatible material that can work for diagnostics and therapy together. To sum up, I would like to check workability of pSi as a candidate for nanotheranostics in this project.