Study On Quantum Dot Fluorescent Sensor For Biomolecule Detection

Fluorescent sensors have several advantages for biomedical research, such as high sensitivity, good selectivity, multi-parameters, wide dynamic range, simple and low cost. Due to their unique photophysical properties such as size-dependent narrow-band emission, broad-band absorption, and resistance to photobleaching, quantum dots (QDs) fluorescent probes have become a research focus in recent years. In this paper, QDs fluorescent probe is designed for the detection of Avidin based on different mechanisms, ICT (interfacial charge transfer).The main contents are as follows:We synthesized a small molecule phen-biotin (phen-biotin=5-(10-amidobiotinyl)-1,10-phenanthroline)) and combined it with "sesame-ball" liked nanohybrids into ratiometric fluorescent probes. The "sesame-ball" liked nanohybrid was constructed by hybridizing two differently charged quantum dot, in which the red-emitting CdSe/CdZnS/ZnS QDs(rQDs) entrapped by silica shell acting as the reference signal, and the green-emitting CdZnTe QDs(gQDs) serving as the response signal. When aqueous insoluble phen-biotin was adsorbed onto surface of gQDs by phase transfer under the drive of metal-affinity coordination. The photoluminescence(PL) of gQDs was quenched by interfacial charge transfer(ICT) mechanism, while the PL of rQDs kept invariable because of the silica-encapsulation. In the presence of avidin, phen-biotin detached from the surface of gQDs due to the strong-binding with avidin, resulting in the PL restoration of gQDs. Based on the background signal of rQDs, the variations of the sensing system presented continuous fluorescence color changes from red to yellow, which can be easily distinguished by naked eyes. A detection limit of 3 nM and a linear range of 9?1000 nM were achieved with the probe in aqueous solution. Importantly, this ratiometric sensor had proved to feature good selectivity for avidin over other derivatives of avidin and proteins.Meanwhile, we realized the application of the sensor in biomedical engineering for C-peptide detection.