Development Of Alateral Flow Strip Sensor For Chloramphenicol Screening Using Colorants Of Aptamer Functionalized Nanogold Particles

Chloramphenicol(CAP),an effective broad-spectrum antibiotic,was originally used in veterinary practices.Nowadays,CAP is prohibited in many countries since it causes serious side-effects in humans,thus,efficient supervision of CAP can greatly safeguard consumers' health.It is important and urgent to develop efficient and simple analytical methods with high specificity and sensitivity for CAP residue detection.Lateral flow assay strip(LFAS)is chromatography-based simplified sensor formats for rapid,on-site detection of ligands.In recent years,strip biosensors have attracted considerable interest due to their portability,rapid assay time,cost-effectiveness and ease of use.A series of LFAS sensors based on antibody were gradually developed for the detection of CAP.Qualitative or quantitative methods can be developed using specific responses of antigen-antibodies in the lateral flow immunoassays.Even so antibodies are suitable for use in analysis,they are not ubiquitously applicable.The main argument against their use is the requirement that antibodies are produced in vivo.For non-immunogenic and toxic targets,they are not conducive to antibody generation.However,in recent years,a new recognition molecule aptamer is widely used in test.Being short single-stranded DNA or RNA(usually DNA)that can bind to target analytes with a three-dimensional conformation of high specificity and affinity.Herein,a new sensitive and specific strip sensor was developed based on a competitive assay to use colorants of aptamer functionalized nanogold particles for detection of CAP.The optical red bands were visually checked by naked eyes and scanned by the strip reader to achieve a facile quantitation.The new aptamer-based lateral flow assay showed a visual limit of detection(LOD)of 0.5 ppm and scanning reader LOD of 63.4 ppb,respectively.Meanwhile,a pre-incubation process of CAP and the aptamer functionalized nanogold was performed to further improve the sensitivity.Deliberate optimization towards the size of gold nanoparticles,amount of aptamer,the type and pH of SA,the reading time and the blocking procedure were carried out.In addition,the developed strip sensor has high sensitivity for detecting CAP and high specificity towards CAP versus CAP analogs(florfenicol and thiamphenico).The accuracy of the strip sensor in detecting CAP in water was then evaluated by the recovery rate.Different CAP concentrations were spiked in the negative water sample,and the recovery rates were analyzed to be 85.7%-1 10.68%,and the RSD was lower than 8%,indicating that the loss of CAP during sample treatment was acceptable.The strip for chloramphenicol screening using colorants of aptamer functionalized nanogold particles did not require any complicated equipment and was a potential potable tool for rapid identification of micropollutant chloramphenicol in municipal water samples.In addition,the design using nucleic acids pairs for biosensor development can be further referred to for other small molecule micropollutant detection.