Design And Preparation Of Microfluidic SERS Chips And Their Detection Research In Identification Of Blood

The Raman spectrum reflects the information such as the extension and bending of the chemical bonds of the sample molecules,and is particularly suitable for the rapid and non-destructive testing of biochemical samples because of its strong penetration force,and non-interference with by the water with weak Raman effect.However,the signal of the normal Raman spectrum is weak,often be enhanceed with the aid of SERS substrates.As the composition of the biochemical samples is complex,seriously affeted by the background fluorescence,causing the difficult identification of characteristic peaks,resulting in difficult interpretation of SERS spectra,which leads to the less application of SERS spectra in the actual detection of biochemical samples.In this study,a new SERS substrate was designed and fabricated with graphene with fluorescence extinction and Au NPs with superior SERS enhancement effect.It was integrated with microfluidic chip and applied to detection and identification of different types of blood samples and disease blood samples,combined with mathematical statistics to establish a discriminant model,to provide new ways and test methods for the identification of blood species and diagnosis of diseases rapidly.The related research has a clear research significance in the application of Raman spectroscopy in biochemical analysis,and it has a very good application prospect in the fields of disease diagnosis,criminal investigation and inspection and quarantine of import and export.The main research work and results are as follows: 1.Design,preparation and testing application of graphene/Au NPs nanocompositeITO@Au NPs-SLG?S_??,ITO@SLG-Au NPs?S_??,ITO@Au NPs-SLG-Au NPs?S_??SERS-active substrates were designed and fabricated,the SERS testing result of the same concentration of R6 G on these SERS-active substrates shows that S_? substrate has the best SERS enhancement effect.Combined with the SEM,the S_? substrate combines the better chemical enhancement of graphene and excellent electromagnetic field enhancement of Au NPs to achieve the synergistic enhancement effect of electromagnetic enhancement and chemical enhancement.The addition of graphene also increases the background fluorescence extinction and biocompatibility of the substrate.The detection limit for R6 G on S_? substrate was 1.00×10^-9 M,the enhancement factor was 4.85×10⁷,and the SERS signal of the Salmonella typhimurium,RBCs and leukocyte samples could be increased by about 100 times.The SERS substrate has good detection sensitivity and test repeatability and can be applied to biological sample analysis.2.Multi-channel SERS chip integrated with Au NPs-SLG-Au NPs nanocomposite substrate for the identification of blood species of human,dog and rabbitA microfluidic multichannel SERS chip integrated SERS nanocomposite material was designed and fabricated,of which three capillary injection channels were prepared on the PDMS cover sheet,and Au NPs-SLG-Au NPs composite SERS-active substrate was fabricated on indium tin oxide?ITO?-coated glass.This SERS chip was applied to non-destructive SERS testing of whole blood of human and animals,and SERS spectra of 35 human blood,35 dogs and 35 rabbits were obtained under the best test conditions.The SERS spectra of 30 human blood,30 dogs and 30 rabbits were statistically analyzed and established a mathematical model with a correct rate of 93.33%,and the correct rate of blind testing of 5 human blood,5 dogs and 5 rabbits,reached 93.33%.Therefore,a new method to identify blood species based on SERS spectra was established.At the same time,the results show that the differenct characteristic peaks of SERS spectra between human and animal blood are mostly attributed to the nucleic acid base and amino acids,which is consistent with theoretically that the differences of human and animal blood are from DNA,RNA and protein.The established new methods can be widely promoted in the criminal investigation and import and export inspection and quarantine areas.3.Microfluidic SERS chip integrated with graphene/Au NPs nanocomposite substrate for the identification of plasma from normal human and hepatitis patientA microfluidic SERS chip integrated graphene@Au SERS nanocomposite substrate was designed and fabricated,of which ITO@Au NPs-SLG-Au NPs SERS-active substrate was embedded on the PDMS cover sheet,and the microfluidic channels and cavities are etched on the glass surface,to obtain a composite integrated chip to achieve blood sample separation and on-line SERS detection.This chip is applied to normal human and hepatitis patients plasma SERS test,to achieve non-destructive testing and rapid identification of blood samples.SERS spectra of plasma were obtained from 41 normal human and 35 hepatitis patients,under optimal blood separation conditions and SERS test conditions.The SERS spectra of 36 normal blood and 30 hepatitis patients were baseline corrected-principal component analysis and established a mathematical model with a correct rate of 95.50%,and the correct rate of blind testing of 5 human blood,5 hepatitis,reached 90.00%.So a new method for plasma identification of normal blood and hepatitis patients based on SERS spectroscopy was established.At the same time,the results show that the raising peaks of patients most derived from alanine and other amino acids,the lower part derived from globulin,which is consistent with theoretically that the increasing of transaminase lead to the increasing of amino acids when liver function is damaged,and liver cell damage inhibits the synthesis of proteins.which is consistent with theoretically that the differences of human and animal blood are from DNA,RNA and protein.The established new methods can be widely promoted in the field of disease diagnosis,and disease census.