Multicomponent silicon-based nanoconstructs for biological and electronic applications
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Quantum dots (QDs) exhibit size-dependent optical properties that make them advantageous for use in bio-imaging, traceable delivery and therapy. There is a widespread interest and research effort in use of group II-VI QDs for these purposes. However, group II-VI quantum dots contain heavy metals that are toxic and thus, there is a need to replace them with a more biocompatible QD like silicon. In this work, we report the preparation of silicon QDs in an aerosol reactor by laser pyrolysis, followed by etching, to produce luminescence, and grafting with organic molecules, to create an oxidation resistant quantum dot surface. These QDs along with doxorubicin (cancer therapeutic) are co-encapsulated within folate- and PEG-terminated phospholipid micelles in an aqueous environment. These aqueous dispersions of micelles are then studied to determine their photoluminescence, targeting capabilities and cyto-toxicity. The aqueous dispersion of the phospholipid micelles co-encapsulating the QDs and doxorubicin constitute the targeted drug delivery system. Silicon-germanium alloy nanoparticles may be of interest for a variety of electronic and optoelectronic applications primarily due to the tunability of their band gap from infrared to the visible range of the spectrum. In this work, we present the synthesis of free-standing silicon-germanium alloy nanoparticles via an aerosol synthesis method where simultaneous laser pyrolysis of silane and germane produces the alloy nanoparticles at high rates (50-1500 mg/h). The results of their characterization using SEM-EDS, XRD, TEM, FTIR and TOF-SIMS are presented here. The preparation of macroscopic quantities of silicon-germanium alloy nanoparticles by the method described here paves the way for chemical studies of the free alloy nanoparticles that were not previously possible, as well as for the potential industrial and commercial applications of the alloy nanoparticles.