Development Of Novel Metal Hybrids Nanomaterial Based Mass Spectrometry For Metabolic Analysis And Clinical Applications

Metabolomics is a new discipline for the detection and analysis of all low molecular weight metabolites(MW<1000 Da)in a given organism or cell over a specific physiological period.From the perspective of physiology,the human metabolites can effectively characterize the ongoing pathological or physiological processes.Compared with proteomics and genomic methods,metabolomics research is closest to the biochemical phenotypes,since the biological metabolic activities are at the very end of the body’s overall regulation.At the same time,small molecular metabolites will amplify small changes in gene levels at the biochemical pathways.By monitoring small molecule metabolites,it is possible to systematically grasp changes in the internal and external factors of the body.Therefore,it has aroused widespread interest among researchers in many fields.At present,the common used metabolic detection methods witnessed vast applications,including mass spectrometry(MS)and nuclear magnetic resonance(NMR).The NMR detection enjoys a wide detection range,simple sample preparation,and stable data output,but still has disadvantages such as low sensitivity and bad resolution thus not suitable for quantitative analysis.Compared to NMR,traditional mass spectrometry has high selectivity and sensitivity,but the sample preparation process is complicated,and the detection process will cause loss of some metabolites.Unlike traditional mass spectrometry methods,laser desorption/ionization mass spectrometry(LDI MS)provides fast analysis speed and accurate mass measurement for metabolite identification,and is inexpensive and easy to be used in large-scale clinical trials.However,LDI MS is widely used in the detection of proteomics and peptides,and the matrix decides the analysis efficiency of metabolomics in LDI MS.People always used some organic acid as the traditional matrix in LDI MS,which will be easily broken down under laser and thus causes strong background noise interference at the low mass range.Moreover,the co-crystallization between organic matrix and analytes is not uniform,which will lead to the"hot spot" effect and affect the detection reproducibility.Inorganic nanomaterials have also been developed as the matrices for the detection of metabolites in LDI MS,including metal and metal oxides,carbon-based nanomaterials,and silicon-based nanomaterials.But those materials still have drawbacks in real applications,like low sensitivity,complicated fabrication,and high cost,etc.Except that,the complex nature of clinical biological samples and low abundance of metabolites,make it difficult to analyze metabolites in real samples.In addition,finding a relationship between the metabolome and a qualified clinical sample is also challenging.Thus,we combined the advantages of noble metal for low melting point,high UV absorption,and surface plasmon enhancement,with those of silicon-based nanomaterials for easy functionalization and low heat conductivity,to address the LDI MS application in clinics.In view of the unsolved scientific and application problems in this field,this paper uses the new metal composite nanomaterials as the starting point in mass spectrometry,and studies the application of metabolomics in disease detection,microbial inhibition and pharmacokinetics research.(1)Firstly,we synthesized the novel silver nanoshells using both a hard template method and silver mirror reaction.We optimized the synthetic parameters of nanoshells for LDI MS use,including the reaction time and temperature.Based on this material,we performed high-throughput metabolite detection on a minimal amount of biofluids(e.g.500 nL of serum).We further achieved an accurate diagnosis of brain infected patients,and demonstrated the drug distribution in serum and central nervous system of edema patients before and after medical treatment.(2)To simplify the synthesis process and remove nanomaterials from co-cultivated bacteria,we introduced the magnetic core to prepare silver core-shell nanoparticles as a dual platform to detect and inhibit Escherichia coli(E.coli)at the same time.For bacterial detection,we could detect down to 10 E.coli in infected blood,which promised a highly sensitive diagnosis of infectious patients in clinics.For bacterial destruction,we achieved long inhibition effects towards E.coli,lasting for at least 5 days due to the unique surface roughness and targeted biotoxicity of the silver core-shell magnetic nanoparticles.(3)Pancreatic cancer patients commonly displayed abnormal glucose metabolism.The silver-based core-shell nanoparticles we proposed before tend to be oxidized easily.Moreover,the strong competition adduction of Ag ions will result in difficult molecular identification.In addition,platinum has long been used for its bio-enzyme mimicking catalysis ability and its stable surface chemistry will lead to a clearer mass spectra.Thus,we prepared platinum core-shell magnetic nanoparticles as a multifunctional platform to achieve the point-of-care(POCT)detection of glucose content and precise diagnosis of pancreatic cancer at the same time.For POCT detection of glucose,we quantified glucose content in 5 minutes by platinum-catalyzed color change,using platinum core-shell magnetic nanoparticles as a nano-enzyme.For the precise diagnosis of pancreatic cancer,we used the material as the matrix for LDI MS to collect and extract the metabolome fingerprints in serum,and applied statistical methods to diagnose pancreatic cancer.The diagnostic performance was outstanding,with sensitivity as high as 84%and specificity as 92%.We also identified four metabolic pathways that are highly associated with pancreatic cancer,which promised the downstream biological studies in the future.In summary,we extracted serum metabolic patterns using a series of novel metal hybrids-assisted LDI MS approach and applied these patterns for the disease diagnosis,microbial inhibition,and pharmacokinetics research.Our approach contributes to the design of advanced metabolic analysis protocols that will facilitate precision medicine and lead to the development of personalized diagnostic tools for diverse diseases in the near future.