Visual Sensing Detection Of Multiantibiotics Based On Carbon Dots Paper-Based Microfluidic Chip

Food is the material foundation for human survival,and food safety is a "popular project" related to the health and life safety of the broad masses of people.Antibiotics are a kind of veterinary drugs commonly used in aquatic products,which are usually used to inhibit the pollution and destruction of bacteria to the growth environment and aquatic products themselves.However,the overuse and abuse of antibiotics lead to their residues in food,which has brought certain harm and hidden dangers to food safety and human health.Therefore,it is of great significance for food safety to develop effective antibiotic detection technology.The combination of paper-based microfluidic analytical device detection technology and nanomaterials has the advantages of high sensitivity,low cost,rapidity and convenience,and can realize on-site and instant detection of antibiotics.In this paper,the fluorescent carbon dots(CDs)doped with impurity elements were synthesized by hydrothermal method,and two kinds of paper-based microfluidic analytical device were designed and manufactured.With the fluorescence of carbon dots as the main detection signal,aptamer as the specific recognition factor,combined with portable detection equipment and smartphone,the antibiotics in aquatic products were visually detected.The specific research contents of this study are as follows:1.A two-dimensional paper-based microfluidic analytical device based on multicolor carbon dots(mCD-μPAD)for simultaneous detection of various antibiotics was constructed.The laserprinted mCD-μPAD loaded with multicolor fluorescence nanoprobes was developed to rapidly detect sulfamethazine(SMZ),oxytetracycline(OTC)and chloramphenicol(CAP)on site.These"fluorescence off" detection probes composed of CDs(donor)conjugated with aptamers and MoS2 nanosheets(acceptor)were based on forster resonance energy transfer(FRET).Upon the addition of target antibiotics,the significantly recovered fluorescence signal on the mCD-μPAD can be sensitively perceived by employing a 3D-printed portable detection box through a smartphone.Under optimal conditions,this μPAD allowed for a rapid response of 15 min toward SMZ,OTC and CAP with considerable sensitivities of 0.47 ng/mL,0.48 ng/mL and 0.34 ng/mL,respectively.In shrimp samples,the recoveries were 95.2%-101.2%、96.4%-105.0%and 96.7%-106.1%with RSD below 6%.This paper-based sensor combines the fluorescent carbon dots with the paper-based microfluidic detection technology,which has high sensitivity,good selectivity and low cross-reactivity,and can be used for rapid detection on site,providing a choice for the simultaneous rapid detection of various antibiotics in a complex food substrate.2.A fluorescence-colorimetric dual-mode three-dimensional μPAD for sulfadimethoxine(SDM)detection was constructed based on fluorescent CDs in order to improve the reliability and sensitivity.With Mg,N codoped-CDs as fluorescence signals,silver nanoparticles as colorimetric signals and aptamers as specific recognition factors.When detecting SDM,the aptamer was mixed with Ag NPs firstly.Then the aptamers were specifically combined with the target.Ag NPs that were not protected by aptamer congregated after adding NaCl,and the congregated Ag NPs could not quench the fluorescence of CDs.Based on the principle,a reciprocating 3D-μPAD was designed,which also combined with small portable detection equipment and smartphone digital image recognition technology.Under the optimal conditions,a good linear relationship is observed between the relative colorimetric and fluorescent signals and the logarithm of SDM concentrations with same linear ranges of 10 ng/mL-1000 ng/mL(LOD:0.21 ng/mL and 0.13 ng/mL respectively).The recoveries of SDM spiked in fish are 96.7%-113.6%and 98.2%-105.1%for colorimetric and fluorescent signals,respectively.The 3D-μPAD aptamer sensor has great application value in the field of antibiotic residue detection.