Preparation And Application Of Quantum Dot/Photonic Crystal Composite

There are abundant functional groups on the surface of CdTe quantum dot?QD?,which make it sensitive to external chemical stimulations.The response of hydrogel photonic crystal?PC?to external stimulations can be investigated by monitoring the shift of its Bragg diffraction wavelength.In this paper,a novel QD/PC composite was prepared and its applications for analytical sensors were developed.The main contents of this paper are:1.Polystyrene photonic crystal template was prepared by monodisperse polystyrene microspheres using vertical deposition method.CdTe QD was synthesized in aqueous solution and modified by 3-mercaptopropionic acid?MPA?.Precursor solution was a mixture of vinyl carboxylic acid,acrylic amide,N,N'-methylene bisacrylamide and ammonium persulfate.Then CdTe-immobilized hydrogel photonic crystal was fabricated by filling precursor solution containing CdTe into the interstitial spaces of polystyrene photonic crystal templates,followed by a thermal polymerization.The prepared material was characterized and exhibited a three-dimensional,highly-ordered face-centered cubic structure with a photonic band gap and fluorescent property.Then the influences of the size and content of CdTe on photonic band gap were studied and the result demonstrated that photonic band gap was red shift with the increasing of the size of CdTe,as well as the content of CdTe.2.The response to Cu²⁺ was realized by QD/PC composite based on the complexation interaction between sulfydryl and carboxyl of CdTe and Cu²⁺.The results demonstrated that the composite show best response to Cu²⁺ under the condition of the content of CdTe was 0.02 g and the pH of solution was 5.0.A linear relationship was found between the wavelength of the diffraction peak shift and the logarithm of the concentration of Cu²⁺ ranging from 1.0×10-9 M to 1.0×10-2 M,and the equation was ??=6.8 logc+76.3.The sensing application of composite to ciprofloxacin was also realized based on the hydrogen bond interaction between the carboxyl,secondary amine,carbonyl of drug molecule and the sulfydryl,carboxyl of CdTe.The composite showed the best response to ciprofloxacin when the pH of the solution was 5.0.A linear relationship was also found between the wavelength of the diffraction peak shift and the logarithm of the ciprofloxacin concentration from 1.0×10-9 M to 1.0×10-4 M,and the equation was ??=7.3 logc+72.The method can be used to detect the ciprofloxacin in the eyedrop samples.