Construction And Application Of Chiral Optical Sensor Array

Organism is a natural chiral system,and the biomolecules such as amino acids,polysaccharides,proteins and nucleic acids that make up organism have chirality.Their chirality affects the behavior and function of cells or organisms.Therefore,it is of great significance to develop new methods for analysis the chirality of biomolecules.However,the background interference brought by biological matrix and the subtle structural differences between chiral biomolecules make it difficult for traditional methods such as polarimeter and circular dichroism?CD?to achieve chiral detection in complex biological matrix.In recent years,cross-reactive receptors based sensor arrays have been proved to superior in distinguishing analytes with similar structures and properties in complex matrix,which have great potential in chiral detection of biomolecules in complex matrix.Optical signals are widely used in the design of sensor arrays due to their advantages of high sensitivity,fast analysis and low cost.Therefore,we designed three novel chiral sensor arrays based on optical signals in this paper that applied to chiral detection and drug screening in complex systems.The main contents and results of this paper are as follows:?1?Firstly,we designed a novel chiral optical sensor array by using host-guest chemistry and MoS₂ nanosheet,which applied to the recognition of chiral amino acids.As a result,39 amino acids including glycine,19 L-amino acids which make up proteins and their corresponding 19 D-amino acids were effectively identified through fluorescent indicator replacement assay.The accuracy of training set and unknown samples was 98.7%and 93.6%respectively.The sensor array was applied to identify the enantiomeric purity of amino acid?isoleucine?,and the experimental results showed that the training set samples were completely distinguished,and the discrimination accuracy of unknown samples was 95.8%.As to determine the concentration of amino acid,the canonical factor 1?F1?obtained through L-tryptophan sensing showed a good linear relationship with the logarithm of the L-tryptophan concentration in the range of 20nm-500?M.In addition,the concentration of amino acid in complex matrix could also be effectively determined.For example,the F1 obtained through D-phenylalanine sensing in complex matrix showed a good linear relationship with the concentration of D-phenylalanine in the range of 0-8?M,indicating the potential of the sensor array in the application of real complex samples.?2?Then,we applied the MoS₂ nanosheet based sensor array to monitor the biosynthesis of bacterial peptidoglycan.Five bacteria were effectively identified by using the difference including species,chirality and content of amino acids in peptidoglycan among bacteria.The accuracy of training set as well as unknown samples was 100%.Moreover,the small changes in amino acid composition of bacterial peptidoglycan under the different growth stages and stimulation with exogenous D-amino acids could be effectively monitored.Linear discriminant analysis?LDA?showed that the changes of amino acid composition of peptidoglycan followed a certain rule,which could be described by the canonical score plot of discriminant analysis.When the sensor array was used to sense the peptidoglycan of Staphylococcus aureus with different culture time,F1 increased gradually with the increase of culture time,and the score plots was gradually close to the right boundary of the LDA canonical score plot.The monitoring results of the biosynthesis of Escherichia coli peptidoglycan stimulated by exogenous D-amino acids?D-methionine,D-valine and D-phenylalanine?showed that exogenous D-amino acids were synthesized into the short peptides of peptidoglycan.This sensor array is fast,high throughput and has great advantages in the analysis of mixture,which has a good application prospect in the real and complex biological samples.?3?Secondly,we constructed a chiral plasmonic sensor array for comprehensive analysis of proteins.The sensor array was composed of ligands modified Au islands films?AuIFs?.AuIFs have the properties of plasmon resonance enhancement and ligands have different selectivity to secondary structures.Through the transduction of CD signals,23 proteins were effectively identified,and the accuracy of training set and unknown samples was 98.6%and 92.8%respectively.The results of hierarchical clustering analysis showed that the recognition of the sensor array to proteins mainly relied on the secondary structures of proteins.Then,we initially explored the application of this sensor array in complex mixture proteins.The sensor array showed excellent discrimination for mixed proteins with the same secondary structure fractions.In addition,the sensor array could be used to monitor the fibrosis process of A?₄₂,which is the typical biomarker of Alzheimer's disease?AD?.According to the resluts of LDA,the fibrosis process of A?₄₂ followed a certain trajectory in the canonical score plot,which could be used to judge the progression of AD.When the concentration of A?₄₂ aggregates was in the range of 10 nm-5?M,the obtained F1 from array sensing showed a good linear relationship with the logarithm of the concentration.The sensor array could detect A?₄₂ at pM level by using the enrichment function of receptors.Moreover,the sensor array was reusable and anti-interference,thus it has great potential in the study of complex protein mixture.?4?Then,we applied the AuIFs based sensor array to the research of proteomics.The results showed that the proteins absorbed by receptors could be directly analyzed without eluting by using matrix assisted laser desorption ionization time of flight mass spectrometry?MS?.The sensitivity of MS detection for low abundance protein was greatly improved after absorbed by receptors.The diagnosis of the disease progression of AD could be realized by using MS imaging.A comparative study on the secretory proteome of two types of hepatocellular carcinoma cells?HepG2 and Hep3B?showed that receptors had a good enrichment effect on low-abundance proteins,and a large number of low-abundance proteins were identified through the enrichment by receptors,which greatly expanding the scope of proteome research.Analysis of the secondary structure of the proteome revealed that the mechanism of protein enrichment mainly relied on the secondary structure of proteins.By analyzing the biological function of proteins,it could be found that the molecular function of proteome has been significantly changed after the selective absorption by receptors.By comparing the correlation between secretory proteins and cancer development before and after receptors adsorption,it could be seen that after enrichment by receptors,the proportion of proteins related to cancer development in the secretory proteome increased significantly,and the difference of the cancer-related protein proportion between HepG2and Hep3B was increased.These results suggested that the sensor array was more conducive to identify cancer cells and discover biomarkers related to cancer development.The sensor array could not only analyze complex mixed proteins through CD signals,but also enrich low-abundance proteins in complex proteome,and could be directly used with mass spectrometer,which has a great application prospect in proteomics.?5?Thirdly,we designed a sensor array for G-quadruplex?G4?ligand screening and its mechanism by using the chirality of G4 DNA.Eight ligands with known interaction modes were used to establish the training set and its validity verified by five unknown ligands.The results showed that the accuracy for identifying the interaction modes of ligand through the training set was 100%.Compared with fluorescence method,the sensor array could reduce the interference of background signal and improve the accuracy of discrimination.In addition,we preliminarily explored the application of this sensor array in the screening of ligands in complex mixtures.The results showed that this sensor array has the ability to selectively capture low-concentration ligands in complex mixtures,and the captured ligands could be eluted and identified by MS,thus providing a new idea for drug screening.The three kinds of sensor arrays constructed in this paper are novel and effective,and their design and sensing mechanism have not been reported.By using the three sensor arrays,we systematically studied the chiral biomolecules.Our research included the recognition of amino acid enantiomers,monitoring the biosynthesis of bacterial peptidoglycan,identification of proteins,diagnosis of conformational diseases,study on complex proteome,and screening of drugs,which have important significance on biology,pharmacy,medical diagnosis,biomedical materials and other fields.