Systematic investigation of the aqueous processing of CdSe quantum dots and CuS nanoparticles for potential bio-medical
- PDF / 555,308 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 95 Downloads / 143 Views
Systematic investigation of the aqueous processing of CdSe quantum dots and CuS nanoparticles for potential bio-medical applications. Raquel Feliciano Crespo1, Oscar Perales-Perez2, Sonia J. Bailon-Ruiz2 and Maxime J-F Guinel3 1 Department of Chemistry, University of Puerto Rico, Mayaguez, PR. 2 Department of Engineering Science & Materials, University of Puerto Rico, Mayaguez, PR. 3 Department of Physics, College of Natural Sciences, University of Puerto Rico, San Juan, PR. ABSTRACT Semiconductor quantum dots are considered very promising candidates for bio-imaging and diagnosis applications because of their tunable optical properties and good optical stability in aqueous phase. Any practical application of these materials will rely on the viability of their simple and direct synthesis in aqueous phase with no need for toxic and unstable organic media. The optical properties of CdSe quantum dots and CuS nanoparticles are desirable in bio-imaging and cell sorting applications because of their tunable photoluminescence at the visible range. The present work addresses the synthesis of CdSe quantum dots and CuS nanoparticles via an optimized, simple and scalable aqueous processing route at low temperatures. The tunability of the optical properties was achieved by a suitable control of the citrate/Cd mole ratio, temperature of synthesis (20-90°C) and reaction time (0-1 hour). In the case of CuS, the strong plasmonic absorption offers the opportunity to investigate this material as a photothermal coupling agent for photothermal therapy. The intensity of the plasmonic absorption was enhanced by selecting an appropriate sulfide precursor (Na2S, Thioglycolic acid), temperature of synthesis (90-120°C) and reaction time. Nanocrystals were characterized by x-ray diffraction, UV-VIS, photoluminescence (PL) spectroscopy techniques and electron microscopy. The effects of the synthesis conditions on the crystal size and the corresponding functional properties of synthesized quantum dots are presented and discussed. I. INTRODUCTION Nano particles (NP) and quantum dots (QDs) exhibit unique optical properties that make them promising candidates for nanomedicine applications, such as bioimaging, photodynamic therapy (PDT) and photo-thermal ablation (PTA) [1,2]. These novel nanotechnologies require stable and high quality water-soluble quantum dots [3]. However, the direct synthesis of water-soluble QDs, e.g. CdSe and CuS, exhibiting high stability in biological environments is a very challenging task. To overcome this limitation, the uses of biocompatible capping agents to stabilize QDs are suggested. Citrate ligand species have been used to control crystal growth and promote the quantum yield in semiconductor QDs [4,5]. Although the synthesis of QDs using organometallic complexes routes have been reported elsewhere, the reports on the direct synthesis in aqueous phase of water-stable nanocrystals, e.g. CdSe, are scarce or preliminary. Several studies attributed the toxicity of CdSe QDs to surface oxidation of the nanocrystals or remo
Data Loading...
