Preparation Of Doped CdTe:Mn Quantum Dots And Its Detection Of Cu²⁺ And Ascorbic Acid

Quantum dots are kinds of nanocrystalline material whose size is between single molecules and three-dimensional materials.Compared with organic dyes,quantum dots have many outstanding advantages,including adjustable quantum size,large-extinction coefficient,high fluorescence quantum yield and good photostability.And they are widely used in biomedicine,analytical testing and other fields.Meanwhile,the doping of transition metal ions can effectively modify the surface defects of quantum dots.Besides,the surface chemical potential of cubic phase quantum dots is high,thus,it is more accessible to adsorb ion doped.So far,the properties of Mn-doped CdTe nanoparticles have not been explored in depth,so it is expected to develop Mn-doped CdTe quantum dots to meet further application in some fields.In this strategy,one-pot aqueous synthesis of CdTe QDs and CdTe:Mn QDs was carried out.Firstly,CdTe QDs were synthesized in the water phase where sodium hydride(NaHTe)was used as the precursor,cadmium chloride(CdCl2)was used as the cadmium source,and 3-mercaptopropionic acid(3-MPA)was used as the stabilizer.What's more,CdTe:Mn QDs were synthesized in the autoclave,in which the sodium hydride was used as the precursor,the cadmium chloride was used as the cadmium source,and the manganese sulfate(MrnSO4)was used as the manganese source.The factors affecting quantum dots such as temperature,pH,reaction time and reactant ratio were discussed.The CdTe QDs and CdTe:Mn QDs obtained by experiments were characterized by fluorescence spectrophotometer(F-7000),ultraviolet spectrophotometer(UV),transmission electron microscope(TEM),scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray diffractometry(XRD)etc.It was concluded that the fluorescence property was effectively improved by Mn-doped CdTe quantum dots.Based on the fluorescence quenching effect,CdTe:Mn QDs was used as a fluorescent probe to establish a rapid and simple analytical method to quantitatively detect Cu2+.The results show that the fluorescence intensity F0/F increases linearly with the concentration of Cu2+ in the range of 5-50 nM,the linear correlation coefficient R2=0.99302 and the detection limit is 5.09 nM,which is expected to be used for the detection of Cu2+ in actual samples.In order to detect Cu,U more effectively,the conditions such as the concentration and pH of buffer,the concentration of quantum dots were optimized.At the same time,interference and selectivitive experiments were performed to ensure high selectivity of the probe;In addition,ascorbic acid(AA)can restore its fluorescence by redox reaction with Cue+-CdTe:Mn QDs due to its strong reducibility,thus a kind of fluorescence analysis method was established that the CdTe:Mn QDs were utilized as a probe to detect AA in the presence of Cu-in the range of AA concentration of 10 to 250 ?M,thefluorescence intensity F0/F shows a good linear relationship,the correlation coefficient R2=0.99253 and the detection limit is 3.06 ?M.