Synthesis and Applications of Luminescent Quantum Dots in Bioassays.

摘要

Luminescent quantum dot (QD) based probes have gained significance in the last decade for optical imaging of cells, tissues and in bioassays as alternatives to conventional organic fluorophores. The main objective of my PhD dissertation was to develop luminescent quantum dot based bioassays for real time monitoring of enzyme activity and simultaneous detection of several biomarkers. The quantum dot based bioassays developed will be potential tools in identification and diagnosis of several ailments that interfere with normal living conditions of human beings.;In Chapter 2 new liposome encapsulated quantum dot based fluorescence resonance energy transfer (FRET) probes have been fabricated and characterized for monitoring the enzymatic activity of phospholipase A2. The probes were able to detect the enzyme activity as low as 0.0075 U/mL (PLA 2 = 1500 U/mg) in 30 min. Further these FRET probes were also used to screen the inhibition efficiencies of phospholipase A2 inhibitors.;Chapter 3 focuses on the first time synthesis and characterization of liposome encapsulated InP/ZnS quantum dots while preserving the integrity of the liposomes. Results from the experiments to assess photostability and effect of pH on the optical properties of InP/ZnS QD-liposomes showed greater advantages over InP/ZnS quantum dots demonstrating their utility as a potential tool in several biological applications such as bio imaging, bioassays and in immunoassays.;Chapter 4 discusses the development of fluorescence based immunoassay for simultaneous detection of the cardiac biomarkers troponin T and troponin I using CdSe/ZnS quantum dots. The assay achieved a detection limit was 0.1 pg/mL for both biomarkers troponin T and I. The method was highly specific for the both the biomarkers with no observed cross reactivity. The multiplex assay was able to detect two biomarkers simultaneously that will yield a high throughput diagnostic tool for heart attack.;A similar method discussed as above was used in chapter 5 for the simultaneous detection of atherosclerosis biomarkers. The detection limits achieved in this study are comparable to the detection limits of the biomarkers reported so far. Incorporation of QDs in silica beads before conjugation to antibodies might improve detection limits that will also improve risk assessment.