Application Of Functional ZnS Quantum Dots To Detection For Cephalosporin Antibiotics

Based on some status of cephalosporins and the optoelectronic properties and application of quantumdots (QDs), function ZnS QDs were used as probes to detect cephalosporin antibiotics. Moreover, theinteraction mechanisms between them were researched, and new methods were established for detectingcephalosporins antibiotics. Then the works were briefly described as follows:1. Determination of Ceftriaxone Sodium by Fluorescence Probes of L-Cysteine Capped ZnSQuantum DotsL-cysteine capped ZnS (L-Cys-ZnS) quantum dots (QDs) were successfully prepared by wet chemicalroute, which were characterized by atomic force microscope, X-ray diffraction, infrared spectrometry,ultraviolet and fluorescent spectrometry. And ceftriaxone sodium (CRO) could cause decrease offluorescence signal of L-Cys-ZnS QDs. Based on this, a new method to determine CRO was established.Under the optimal conditions, fluorescene quenching intensity increased linearly with CRO concentrationin the range from6.00to20.00mg/L with the detection of limit was0.05mg/L, and the linear equation wasΔF=111.93+6.71C (r=0.9959). Further, possible mechanism of the interaction between L-Cys-ZnS QDs andCRO was discussed, and binding constant and sites were Ka=3.354×102, n=0.601.This method to detectCRO was simple and rapidly with high sensitivity.2. Preparation and Application of ZnS:Mn QDs as Resonance Light Scattering Probe to DetectCefotaxime SodiumMn-doped ZnS QDs were synthesised successfully and used as new resonance light scattering (RLS)probe. Then, an interaction between cefotaxime sodium (CTX) and ZnS:Mn QDs results in a considerabledecrease of RLS signal of the ZnS:Mn QDs. Based on this phenomenon, a new method was developed fordetermination of CTX. Under the optimal conditions, with the quenching RLS signals, the linear range ofcalibration curve was1.0×106–2.0×105mol/L for CTX. The linear regression equation wasΔF=225.46+1.0810-7C (r=0.9961) with the detection limit of1×10-9mol/L. Compared with other methods,this method was more sensitive, fast and reliable, which was significant for broadening the applicationfields of QDs. 3. Preparation of ZnS:Ni/ZnS quantum dots with core/shell structure and application for detectingcefoperazone–sulbactamZnS:Ni quantum dots (QDs) have been synthesized via a water-soluble route, which were coated byZnS shell through surface modification to give ZnS:Ni/ZnS QDs. Then, a novel method for thedetermination of cefoperazone–sulbactam (CPZ–SBT) in aqueous solutions has been developed based onthe enhancement of fluorescence of ZnS:Ni/ZnS QDs in the presence of CPZ–SBT. Under the optimalconditions, the enhanced fluorescence intensity was proportional to CPZ–SBT concentration in the range of8.0×10-6–1.0×10-4g/L, The linear equation was ΔF=97.616+26.356C（r=0.9986）with detection limit of1.0×10-7g/L. The method was employed for the determination of CPZ–SBT in sample to give satisfactoryresult. Compared with others, this method was more sensitive, fast and simple with low limit detection.