Label And Label-free SERS Detection Of Bacteria For Discrimination,Sorting And Quantitation

Rapid,accurate discrimination and detection of bacteria is a highly topical research area for the sake of public health and resource exploration.Benefiting from advances in nanotechnology,Raman spectroscopy has been more effectively researched and developed.The SERS effect can produce 106-1014 times signal enhancement and can achieve the sensitivity required for single molecule detection.Surface-enhanced Raman scattering has been considered as a powerful and attractive technique for bacteria detection,due to its high speed,perfect sensitivity,excellent optical stability,comparatively low cost,non-destruction,free-separation,no interference from water,multiplexing ability and portability.SERS can directly obtain the fingerprint information of the sample and achieve on-line,multi-component simultaneous detection.In this paper,we carried out the following researchs in the field of microbiology with the aid of label and label-free SERS technology:1.SERS was used for the first time to our knowledge to investigate two species of methanotrophs and four closely relevant bacteria,considering that MOB have been proved to be a biological indicator for gas prospecting and closely relevant bacteria that universally coexisted in the upper soil of natural gas can be auxiliary indicator.A more convincing multi-Raman criterion based on single Raman bands,and further the entire Raman spectrum in combination with principal component analysis(PCA),which were found capable of classifying MOB related bacterial cells in soil with an accuracy of 100%,along with 100%accuracy on predicting test samples.As a sensitive,rapid and facile method,SERS has been proved to be feasible to discriminate gas relevant bacteria with the distinct merits of easy to operation,cultured independence and high accuracy.Therefore,SERS assay can be employed as a promising tool for selective discrimination of gas related bacteria and will provide new avenues for the gas exploration.2.A novel SERS tag was reported,exploiting bacterial aptamers as recognition element and non-optically interfered alkyne compounds as reporter,achieving rapid detection and sorting of a single bacterium with the aid of laser confocal microscopy Raman instrument and microfluidic chip.On the one hand,the SERS signal of bacteria can be collected via SERS mapping to achieve ultra-sensitive SERS detection on the plate,which can capture and immobilize bacteria quickly and efficiently processd by paraformaldehyde.On the other hand,the bacterial cells can be individually detected and sorted in Raman detection area with the help of the sheath flow technology of the chip.3.We report a rationally designed chitosan-encapsulated and alkyne-coded SERS probe,providing a highly efficient and rapidly quantitative detection method for bacteria universality.Firstly,the SERS probe is simple,rapid,and inexpensive to synthesize.And it can be quickly targeted to the surface of the bacteria by electrostatic action.In addition,alkyne reporter with the best sensitivity,the narrowest spectral line width,and the most suitable signal position is selected at the same time which can effectively circumvente the influence of the miscellaneous peaks of the bacterial components.The linear range was 101-07 cell/M1 with the limit of detection of 10 cell/mL for bacteria.In short,this strategy does not need any culture or enrichment operation,providing a reliable and universal method for the rapid and simple quantitative detection of bacteria.