Aqueous Processing of L-Glutathione Capped ZnO Quantum dots for Potential Biomedical Applications
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Aqueous Processing of L-Glutathione Capped ZnO Quantum dots for Potential Biomedical Applications
Raquel Feliciano-Crespo1, José A Rodriguez2, Myrna Reyes-Blas1, Chuan-Jian Zhong3 and Oscar Perales-Perez2 1 Department of Chemistry, University of Puerto Rico, Mayaguez, PR, USA. 2 Department of Engineering Science & Materials, University of Puerto Rico, Mayaguez, PR, USA. 3 Department of Chemistry, State University of New York, Binghamton, NY, USA. ABSTRACT Medical research has demonstrated the importance of the utilization of stable, fluorescent nanoprobes. The present work addresses the applicability of biocompatible and fluorescent ZnO nanoparticles as probes for detection of pathogens with the aim of achieving extremely low detection limits. For this purpose, ZnO surface must be functionalized for its subsequent interaction with bacterial cellular membrane (coupling), which will allow the corresponding detection and quantification. Herein we will discuss the aqueous synthesis of stable, water soluble and biologically compatible ZnO nanoparticles (NPss) capped with Lglutathione (GSH). The understanding of the interactions between GSH molecules and surface atoms in ZnO QDs became critical to foster the applicability of this nanomaterial in the biomedical and bioengineering fields. In this regard, the GSH/ZnO molar ratios, reaction temperature (40°C and 60°C), time and pH (6-9) became crucial factors to attain suitable tuning of the QDs properties. ZnO/GSH synthesized QDs were characterized by Transmission Electron Microscopy, X-Ray Diffraction, FT-IR, UV-Vis and photoluminescence (PL) spectroscopy. The QDs shape was spherical with a particle size between 80-100nm. The synthesis of ZnO/GSH under different experimental conditions and the corresponding coupling with E. Coli species, are presented and discussed. I. INTRODUCTION Photoluminiscence semiconductors nanoparticles have received a great interest to be used as biological target labels. ZnO nanoparticles have been intensively studied for applications in chemical sensing, photocatalysis and bio imaging, due to their low toxicity. However, there is a need to study the effect of surface modifiers on ZnO NPs for increased quantum efficiency and fluorescence stability. This achievement would enable the use of ZnO as a sensitive, qualitative and quantitative tool for pathogen targeting, imaging and diagnosis. On this basis, this research addressed the synthesis of highly monodisperse ZnO nanoparticles and their capping with reduced L-Glutathione species (GSH). GSH is selected based on its capability to protect red cell from oxidative damage, exhibits an antioxidant nature, binding capacity to toxins, heavy metals, pesticides and can transform them into a form that can be excreted by urine or bile. These features justifies the need to get a deeper understanding on the reactivity of GSH with ZnO NPs. ZnO functionalization with GSH will also facilitate a suitable coupling with biological entities (bacteria and cells), which would enable them to be sued for pathogen detec
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