Construction Of A Bacterial Colorimetric Sensing Platform Based On Molecular Recognition And Its Application In The Diagnosis Of Urinary Tract Infections

Bacterial antimicrobial resistance caused by the abuse of antibiotics has become a new threat to global human health.Developing a rapid,accurate and economical bacterial detection technology is one of the key to solving this problem.Taking urinary tract infections（UTIs）as an example,timely and accurate identification of bacteria and their sensitivity to antibiotics is the core of UTIs management.In recent years,based on the combination of molecular recognition and nanomaterials,the visual biosensor with high selectivity and portability of fixed-point diagnosis has shown great potential in improving the disadvantages of time and labor consumption for traditional UTIs diagnosis.In this study,a nano-colorimetric analysis strategy based on lectin and antibiotic recognition of bacteria was designed,which could realize rapid and visual bacterial detection with extra identification and susceptibility evaluation,expected to accelerate the diagnosis process of clinical UTIs.The main contents and results of this research are as follows:1.Rapid detection of bacteria.Based on concanavalin A modified gold nanoparticles（Con A-AuNPs）,the carbohydrates of the bacterial cell wall could be rapidly recognized,causing the color of gold nanoparticles to change with the degree of aggregation.Bacteria could be detected at the minimum concentration of 10² CFU m L^-1 within 30 minutes.2.Identification of gram-positive and gram-negative bacteria.Due to the different affinity of vancomycin and polymyxin B to gram-positive and gram-negative bacteria,the prepared vancomycin-modified gold nanoparticles（Van-AuNPs）and polymyxin B modified Prussian blue nanoparticles（PMB-PBNPs）could identify different bacterial species in 2–6 hours with the detection limit of 10³CFU m L^-1.3.Rapid antibiotic resistance testing.Combining the traditional broth dilution method with one of the three nanomaterials mentioned above,the minimum inhibitory concentration of antibiotics was determined according to the turning point of nanomaterial color change.