| Quantum dots(QDs)are widely used as chemical sensor for the detection of analytes due to their unique optoelectronic properties.However,traditional fluorescent detection often faces with the influence of the coexisting substances,especially those materials,which have similar structure and performance.Therefore,the selectivity of QDs needs to be improved and the new construction methods need to be developed.Molecularly imprinted polymers(MIPs)have many advantages,such as satisfactory practicability,desired predetermination,good stability,and specific selectivity.Herein,it is reasonable to believe that molecular imprinting technique will be a powerful tool to improve the selectivity of the optical detection,and the novel composite material will integrate the merits of high selectivity of MIPs and fluorescence property of QDs.To date,the synthetic methods and detect techniques about the MIPs-based QDs are few.Therefore,novel strategies and methods for fabricating high-performance MIPs fluorescent sensors and the new detection methods are required.In addition,compared with the traditional imprinted matrix materials(organic polymer,silicon based),mesoporous silicon has regular,adjustable pore size and super high specific surface area.Mesoporous silicon used as molecularly imprinted matrix can effectively memorize and retain the recognition sites of binding sites,increase the adsorption capacity.In this paper,we have prepared a series of mesoporous molecular imprinted fluorescent probes based on Mn doped ZnS quantum dots,CdTe quantum dots and C3N4 as fluorescent carriers,combined with high selectivity of molecularly imprinted polymers.And the main contents were as follows:Tetracycline was used as template molecule and propyl triethoxy silane isocyanate was used as functional monomer to prepare molecularly imprinted polymers.Then the combination of polymers and Mn doped ZnS QDs were completed under the action of mercaptopropyltrimethoxysilane.A fluorescent sensor with highly selective molecularly imprinted polymers is prepared.The fluorescent probes were characterized by transmission electron microscopy,Fourier transform infrared spectroscopy,ultraviolet spectroscopy,X-ray powder diffraction,nitrogen adsorption desorption experiments and fluorescence spectra.The properties of the molecularly imprinted quantum dot composites and the fluorescence quenching relationship and mechanism of tetracycline were investigated by the test results.Under the optimal conditions,the fluorescence response of composites was linearly proportional to tetracycline concentration in a wide range from 50 to 1000 ng·mL-1 with a detection limit of 15 ng·mL-1.Finally,the method has been used to detect tetracycline in plasma samples and gave recoveries in the range from 90.2%-97.2%with relative standard deviations in the 2.2%-5.7%range.A dual-emission ratiometric molecular imprinted fluorescent probe was prepared by using CdTe quantum dot with different emission wavelengths as the ratio of fluorescence materials.The red emitting QDs was used as a reference material,and the green emitting QDs was used as a response substance.The 3-mercaptopropionic acid modified r-QDs were coated into silica-spheres by a reverse micro-emulsion method.Then,r-QD@SiO2 was used as the core,3-mercaptopropionic acid modified g-QDs as auxiliary monomer,MEL as template molecule,3-aminopropyltriethoxysilane as functional monomer,and tetraethoxysilane as crosslinking agent,to prepare the core-shell probe using the sol-gel method.The possible interferers in the homologues and sample systems of melamine have been studied.The process of visualization and selective recognition of melamine and the possible fluorescence quenching mechanism were also discussed.The fluorescence analysis can get good results at the pH 8 and the binding time of more than 10 min.At the same time,the concentration range from 50 to1000 ng mL-1 melamine was detected.The material was applied to the detection of melamine content in milk samples,and the detection limit was 13 ng mL-1.The dual-emission ratiometric molecular imprinted fluorescent probe was prepared by using C3N4 and CdTe QDs as the fluorescence materials.The blue emitting C3N4 was used as a reference material,and the red emitting QDs was used as a response substance.The C3N4 coated silicon was obtained by sol-gel method and then used as the carrier,3-mercaptopropionic acid modified r-QDs as auxiliary monomer,3-aminopropyltriethoxysilane as functional monomer,malachite green as template molecule,and tetraethoxysilane as crosslinking agent,to prepare the core-shell molecular imprinted fluorescence probe.A series of characterization methods are used to analyze the size,morphology and stability of the material.The optimum conditions for the detection and analysis of malachite green were investigated and a series of malachite green adsorption experiment were also completed under this condition.Under the optimal conditions,the fluorescence response of composites was linearly proportional to tetracycline concentration in a wide range from 50 to 1000 ng·mL-1 with a detection limit of 10 ng mL-1.The non-imprinted polymers were compared and the imprinted factor 3.23 was obtained.Finally,the material is applied to the detection of malachite green content in environmental water samples.The recovery rate and relative standard deviation are 92.3%-97.9%and 2.7%-6.3%,respectively.The possible fluorescence quenching mechanism between them was also analyzed. |
PDF Full Text Request