Quantum dot sensor technology

Quantum dot sensor technology, relying on the unique physical and chemical properties of quantum, shows application potential in many fields. Quantum dots, as nanoscale semiconductor crystals (1 - 10 nanometers), have discrete energy levels due to quantum confinement effect, and special optical and electrical properties.

Fluorescence mechanism:

1. Fluorescence quenching and recovery: Target / ions interact with quantum dots, causing energy or electron transfer, and excited-state electrons return to the ground state through non-radiative processes, causing quenching. For example, in environmental monitoring, mercury ions bind to surface groups on quantum dots, causing fluorescence quenching. By measuring the decrease in fluorescence intensity, concentration of mercury ions can be quantitatively determined; under specific conditions or adding reagents to disrupt the interaction, fluorescence recovery can be used for qualitative and quantitative analysis of target.

2. Fluorescence resonance energy transfer (FRET): Fluorescent quantum dots (donors) that emit light and molecules (acceptors) that can absorb light are brought close together, causing FRET. The excited-state energy of the donor is transferred non-radiatively to the acceptor, which becomes excited emits light, causing a decrease in donor fluorescence and an increase in acceptor fluorescence. In biomedical detection, biological molecules are often labeled, and FRET is to detect molecular binding events and study interaction mechanisms.

Mechanism of change in electrical properties: In chemical sensors, quantum dots are modified on the electrode surface, the adsorption of target gas molecules changes the charge transport between the quantum dots and the electrode, causing a change in the electrode current or potential. By measuring this change electrical signals, the target gas can be detected.

Quantum dot preparation: There are various preparation methods. The chemical solution is simple to operate and can synthesize a large amount. By controlling the temperature, reaction time, reactant concentration, etc., the size, shape, and properties of quantum dots can be controlled, such as the high-temperature thermal injection method, which can synthesize high-quality quantum dots; the molecular beam epitax method can precisely control the number of layers and atomic arrangement of quantum dots growing under ultra-high vacuum, preparing high-quality quantum dots, but the equipment is expensive the process is complex.

Surface modification: In order to improve the stability, biocompatibility, and specific binding ability of quantum dots, surface modification is required.al groups such as antibodies, nucleic acids, enzymes, etc., are connected through chemical means. In biomedical applications, quantum dots modified with antibodies can target cells, and at the same time, improve the dispersion of quantum dots, prevent aggregation, and maintain stable performance.

Signal detection and processing: Fluorescence intensity,, and fluorescence lifetime can be measured using a fluorescence spectrometer and a confocal microscope; electrical signals can be measured using an electrochemical workstation and a fieldeffect transistor. After obtaining the signal, it is processed by complex algorithms and software to remove noise, extract valid information, and ensure reliable and accurate detection results.