Droplet Microfluidic Based On Functional Nucleic Acid For Single Bacteria Detection

With the increasing of bacterial infection and drug resistance,infectious diseases caused by pathogenic bacteria have become one of the main diseases threatening human health.It is reported that more than 2.2 million people died per year resulted from the waterborne bacterial pathogens around the world.Among the waterborne and foodborne bacteria,one of the most common bacteria is Escherichia coli(E.coli)and its infection has become a serious problem in clinical treatment.The key to the prevention and treatment of infectious diseases caused by bacteria is to realize the classification and identification of pathogens on the level of singlebacteria.Therefore,it is vital to develop a rapid and single-bacteria sensitive method for the detection of E.coli.As a new technology,droplet microfluidic technology plays a significant role in single molecule analysis and high throughput screening.To date,a variety of droplet microfluidic systems have been developed for the detection of single bacteria.In this paper,a droplet microfluidic system based on functional nucleic acid was constructed to achieve rapid and single-bacteria sensitive detection of E.coli.The following research were mainly carried out:First of all,this study integrated the RFD-EC1 probe with a commercial droplet microfluidic system and studied its performance of E.coli detection.The constructed method based on deoxyribozyme and droplet microfluidic system can be used to detect E.coli within1.5 hours,and the detection limit of E.coli is 100 CFU/m L.In addition,we developed a method(d DRCA method)that uniquely exploited highthroughput platform(droplet microfluidics),a biomolecule(DNAzyme),and an isothermal signal amplification technique(RCA)to detect E.coli rapidly and selectively at single-cell sensitivity.The method can confine biomolecules to droplets with a diameter of 90μm,accelerate reagent mixing and significantly improve reaction kinetics,thus reducing reaction time and completing E.coli detection in 75 minutes.The detection limit of E.coli can be as low as 1 CFU/m L.The method can also identify urinary tract infections(UTI)from clinical urine samples in only 1.5 hours.Therefore,we envisage that the constructed d DRCA system will play an important role in biological,medical and environmental fields.