Bandgap Engineered And Monochromatic Electrogenerated Chemiluminescence Of CdSe Quantum Dots And Its Biosensing Application

Electrogenerated chemiluminescence (ECL) has many advantages over other optical methods, such as improved signal-to-noise ratio, higher sensitivity and broadest test menu, which has been extensively used in biosensing and medical diagnose. The traditional ECL emitter-Ru(bpy)3+-play a dominant role in fundamental research and clinical diagnose owing to its inherently merit. However, the conventional Ru(bpy)32+/tripropylamine system displayed orange ECL emission with broad ECL spectrum. The advance in ECL suffered from the development of novel efficient ECL emitter. Quantum dots (QDs) provide a promising platform in novel ECL biosensor due to their excellent optical and electrical properties. In this thesis, a dual-stablizer-capped strategy was employed to synthesis a series of CdSe QDs with strong, bandgap engineered and monochromatic ECL emissions in greenish region. This dissertation includes the following three parts:1. A facile dual-stabilizers-capped strategy was developed for synthesizing water-soluble CdSe QDs with efficent photoluminescence (PL) in greenish region. The as-prepared CdSe QDs displayed symmetrical PL peak with full width at half maximum (FWHM) less than47nm, as well as good monodispersity and the highest quantum yield up to29%. HRTEM, XRD and XPS were utilized to characterize the structure features of these samples. This strategy was capable of synthesizing water-soluble CdSe QDs with improved PL quantum yield, narrow PL spectra and well monodispersity.2. Strong bandgap engineered and highly monochromatic ECL emission of CdSe QDs was achieved on glass carbon electrode. The ECL was clearly visible to the naked eyes and the ECL process can be recorded by using a cammer as light detector. The linkage of surface cadmium atoms to the dual stabilizers not only can effectively remove the nonradiative surface state and deep surface trap of CdSe QDs for improved ECL efficiency and monochromaticity, but is also favorable for the electrochemical involved electron and hole injection processes for higher ECL intensity. The size-tunable ECL spectra of dual-stabilizers-capped CdSe QDs are narrow (FWHM less than43nm) and much close to corresponding PL spectra, which indicates a series of bandgap engineered and monochromatic ECL emitters. The ECL signal of CdSe QDs shows acceptable accuracy and precision for the detection of dopamine concentration in the practical drug.3. In order to verify the potential of CdSe QDs in biosensing applications, especially when they are linked to substrate, a monochromatic ECL sensing strategy based on CdSe QDs was proposed for dopamine detection. The ECL sensing platform was constructed with ethylenediamine as link molecule to covalently assemble CdSe QDs on modified glass carbon electrode. This strategy can preserve the completely passivated surface states of dual-stabilizers-capped CdSe QDs. We found that the ECL sensor showed eye-visible, bandgap engineering and monochromatic ECL emission, which could accurately quantify dopamine in real samples. This strategy is promising for highly sensitive bimolecular detection, multiplexed analysis and clinical diagnosis.