Investigation of photoluminescence behavior of Silicon Quantum Dot and its effectiveness as single particle luminescent marker

Abstract

Semiconductor nanocrystals or quantum dots (QDs) have attracted considerable attention during the past few decades owing to their unique optical and electronic properties. Extensive research work has been carried out on traditional quantum dots such as CdS, CdSe, CdTe, CdS/ZnS, CdTe/ZnS, InAs, PbSe etc. to understand their photoluminescence (PL) properties as well as to explore them as luminescent marker for biological imaging applications. However, these QDs possess significant drawbacks in biomedical application due to their potential cytotoxicity and large hydrodynamic diameter. Therefore, it is essential to develop new kind of QDs with bright and photostable luminescence, but with less toxicity and smaller diameter.Recently, highly abundant silicon QDs (Si QDs) with less toxicity and smaller size has emerged as the most promising candidate for optoelectronics and biomedical imaging applications. Earlier, small and monodispersed Si QDs have been successfully synthesized in aqueous medium and applied in several in vitro and in vivo bioimaging experiments. However, cell labeling experiments with hydrophilic Si QDs have been found to be nonselective and nonspecific. These kinds of nonspecific and nonselective cell labeling might occur due to random aggregation of Si QD inside the cell environment. In the literature, there are no earlier reports on the PL characteristics of allylamine-functionalized Si QD in biomimicking environments at single particle resolution. In the present work described in the thesis, the PL behavior of allylamine-functionalized Si QD has been investigated in the presence of charge interfaces similar to that encountered in a cell membrane. In addition, the intrinsic PL properties of water-soluble Si QD and its interaction with biomolecules have been investigated. These Si QDs havealso been successfully used as external luminescent markers to study the mechanism and morphology of polymer–surfactant and protein–surfactant complexes.