Construction And Application Of Cadmium Based Quantum Dot-Au Detection System With Multimodal Optical Response

Optical detection technology has the advantages of high sensitivity,rapid analysis and easy operation,and is widely used in disease diagnosis,environmental monitoring,forensic identification and other fields.However,as a widely used detection technology,single-mode optical detection is difficult to meet the increasingly high practical requirements in terms of reliability,sensitivity and detection range.The signals of multi-mode optical signal detection technology can verify each other and complement each other,which can overcome the shortcomings of single mode detection technology.Therefore,this paper constructs a CdTe quantum dot-Au nanoparticle detection system with photoluminescence and resonant light scattering dual-mode optical response,which achieves reliable and sensitive detection of mi RNA-141.On this basis,a three-mode optical response Cd Se quantum dot-Au nanostar detection system was constructed by integrating resonant Raman scattered signals,which further improves the detection reliability and sensitivity,broadens the detection range,and promotes the application and development of optical detection technology.The main research results are as follows:(1)CdTe quantum dots and Au nanoparticles with overlapping spectra were prepared,and it was confirmed that the ratio of cadmium source to tellurium source,the ratio of mercaptopropionic acid to cadmium source and the reaction time are important factors regulating the size and optical properties of CdTe quantum dots.Based on this,a dual mode optical response photoluminescence-resonance light scattering detection system was constructed through the functionalization of CdTe quantum dots and Au nanoparticles as aptamers and their base complementary pairing with mi RNA.The non-radiative resonance energy transfer and radiation reabsorption between CdTe quantum dots and Au nanoparticles quenched the photoluminescence signals of CdTe quantum dots;At the same time,due to the increase in the volume of the scattering body,the resonant light scattering is enhanced.The two signals can be mutually verified,improving the reliability of detection results.The detection limit of mi RNA-141 is as low as 3.7 f M,with a linear range spanning 6 orders of magnitude(10 f M-10 n M),and exhibits excellent repeatability and specificity.(2)CdSe quantum dots were prepared and their size and optical properties were regulated.At the same time,by changing the concentration of cetyltrimethyl ammonium bromide,the plasma absorption peak of Au nanostar was adjusted,and the spectral overlap of Au nanostars with Cd Se quantum dots was obtained.A three-mode optical response detection system of photoluminescence-resonant light scattering-resonant Raman scattering is constructed.By introducing the resonant Raman scattering signal with strong anti-interference ability,the reliability of detection is further improved.The photoluminescence quenching effect of Au nanostar on Cd Se quantum dots reduces the fluorescence backside of resonant Raman scattered signals and improves the signal-to-noise ratio.The detection limit of mi RNA-141 in this threemode optical detection system is 0.47 f M,and the linear range is 1f M-50 n M.Compared to the above dual mode detection system,the detection limit is improved by an order of magnitude.