Incorporation of Fluorescent Carbon Quantum Dots into Metal-Organic Frameworks with Peroxidase-Mimicking Activity for High-Performance Ratiometric Fluorescent Biosensing

A new ratiometric fluorescent sensor based on the bifunctional carbon quantum dots(CQDs)@metal-organic framework(MOF)nanocomposite possessing peroxidase-mimicking catalytic and luminescent characteristics was developed for hydrogen peroxide(H_(2)O_(2))and cholesterol detection.The incorporation of fluorescent CQDs into the cavities of MIL-101(Fe)MOF with peroxidase-like activities endows the nanocomposite with bifunctional properties.The CQDs@MOF can oxidize o-phenylene-diamine to 2,3-diaminophenolazine by H_(2)O_(2)with yellow fluorescence(556 nm).Meantime,the intrinsic fluorescence signal(455 nm)of CQDs@MOF is inhibited due to the inner filter effect.Therefore,the ratio of the fluorescent intensity is employed as the signal output to construct the H_(2)O_(2)ratiometric biosensor.In addition,the cholesterol can be determined by the ratiometric sensor with high sensitivity.In addition,the total cholesterol in human serum is determined with high accuracy using our ratiometric biosensor.This ratiometric fluorescent platform based on the bifunctional CQDs@MOF provides new insights in the field of bio-sensing.

DNAzyme@CuSNPs dual mimic enzyme probe-amplified chemiluminescent imaging array immunosensor for multiple chicken cytokines detection

The detection of cytokines plays an important role in clinical diagnosis and immune mechanism research of chicken diseases.In this work,a novel and ultrasensitive chemiluminescent(CL)imaging array immunosensor was proposed to detect multiple chicken cytokines based on DNAzyme@CuS nanoparticles(DNAzyme@CuSNPs)dual mimic enzyme signal amplification strategy.DNAzyme@CuSNPs owns excellent peroxidase property,which was modified with second antibody(Ab_(2))to prepare DNAzyme@CusNPs detection probe,and demonstrated high catalysis CL imaging signal due to synergistic catalysis.Chicken interleukin-4(ChIL-4)and chicken interferon-y(ChIFN-y)were used as model analysis samples,the DNAzyme@CusSNPs-based CL imaging immunosensor achieved simultaneous and high-throughput detection of ChIL-4 and ChIFN-y with wide linear range of 10^(-3)-10^(2) ng/mL,and the detection limits are 0.41 pg/mL and 0.36 pg/mL,respectively.The multiplex chicken cytokines CL imaging array immunosensor shows a high sensitivity,wide linear range,excellent specificity and acceptable stability.This research opens dual mimic enzyme signal-amplified strategy to develop sensitive CL imaging immunoassay for chicken diseases detection application.

Covalent organic frameworks functionalized carbon fiber paper for the capture and detection of hydroxyl radical in the atmosphere

Developing a fast,sensitive and convenient method for the detection of hydroxyl radicals(·OH) in the atmosphere could help us know the precursor levels of atmospheric species and control air pollution.In this work,the carbon fiber paper(CFP) functionalizing with a kind of covalent organic frameworks(COFs),formed from 1,3,5-triformylphloroglucinol(Tp) and benzidine(BD)(COF(TpBD)),was firstly used a new platform for ·OH trapping and detection.The COF(TpBD) modified CFP was acted as a filter to impregnate salicylic acid(SA) and a detector to detect 2,5-dihydroxybenzoic acid(2,5-DHBA) which was produced from the reaction between the impregnated SA and ’OH in the atmosphere.This method provided a linearity for 2,5-DHBA from 5.0×10^-14 mol/L 1.0×10^-9 mol/L with a detection limit of 6.9×10^-15 mol/L,which is corresponding to the amount of ·OH from 3.0×10^7 to 6.0×10^11 molecules/cm3 with the detection limit of 4.1×10^6 molecules/cm3.This COF(TpBD)-CFP platform has been successfully applied for the detection of ·OH concentration under different conditions of Yangzhou when the sampling time was shortened to 30 min.This work has provided a new method for atmospheric·OH detection with excellent sensitivity,simplicity,and high speed.