Room-temperature Phosphorescence Sensor Based On Manganese Doped Zinc Sulfide Quantum Dots For Detection Of Antibiotics And Glucose

Quantum dots (QDs) are semiconductor nanoparticle with the sizeof l-100nm. QDs show better optic, electrical, the surface paintabilityproperties, so QDs have broad application prospects in the chemical,electronics, biomedical and other fields. Among them, room-temperature phosphorescent (RTP) QDs are more suitable for targetanalyte in a biological sample detected because of high reliability andstability, long phosphorescence lifetime, without the interferencefrom autofluorescence or scattered light than fluorescent QDs. In thisstudy, RTP construct three kinds of quantum dots having antibioticproperties and glucose RTP nanocomposite sensor.In this paper, the main contents are summarized as follows:(1)The MPA-capped Mn-doped ZnS QDs were synthesized using3-mercapto propionic acid (MPA) as stabilizer in the water phase. Thesynthesized results were characterized with transmission electronmicrocopy (TEM) and phosphorescence spectrum. It turned out thatthe MPA-capped Mn-doped ZnS QDs are in spherical shape andbasically uniform diameter of3.5nm. The maximum excitation peakoccurred at295nm and a narrow emission band was centered at595nm.(2)Based on the RTP properties of Mn-doped ZnS QDs, a simple, rapid, high sensitivity and low detection limit method of detectingciprofloxacin in the solution was established. The detection limit (3σ)of ciprofloxacin is0.3μM, the linear range of detection is1.2-60μMand R2=0.993. For systems without ciprofloxacin and with1.4μMciprofloxacin, the relative standard deviation (RSD) of11continuousparallel detections was3.6%. This method avoids the use ofdeoxidants or other inducers required by conventional methods, andalso avoids the interference from the autofluorescence and scatteringlight of the matrix encountered in spectrofluorometry. No pretreat-ment was needed in all samples, except for dilution.(3)The RTP of Mn-doped ZnS quantum dot was explored to developa new method for detection of gatifloxacin in water phase based onthe relation between the Mn-doped ZnS QDs and gatifloxacin. Thelinear ranges of glucose are1-8μM (R2=0.987) and8-80μM (R2=0.995),with the detection limit (3σ) of0.22μM. Further experiment wasperformed to validate whether the Mn-doped ZnS QDs RTP can beused in determination of gatifloxacin content. The standard additionrecoveries on urine samples added with gatifloxacin are95%-107%.(4) Based on the RTP properties of Mn-doped ZnS QDs, method ofdetecting glucose in the solution was established. The linear rangesof glucose are0.005-0.1mM (R2=0.991) and0.1-0.4mM (R2=0.993),with the detection limit (3σ) of0.0029mM. The standard additionrecoveries on urine and serum samples added with glucose are95%-102%. H2O2is the product of many enzyme-decomposed substrates inlife activities and H2O2affected the RTP of MPA-capped Mn-doped ZnSQDs. Therefore, the ability of the MPA-capped Mn-doped ZnS QDs forglucose detection can be attributed to the quenching of their RTP by H2O2.