Improving Detection Sensitivity Of Surface-assisted Laser Desorption/ionization Mass Spectrometry By Au Nanoparticles And Patterned Si Nanocones

Surface-assisted laser desorption/ionization mass spectrometry（SALDI-MS）is a modern analytical technique suitable for the detection of small molecules.It has the advantages of rapid analysis and high accuracy.To detect small molecule plays an important role in biological research and environmental monitoring.With the development of society,higher requirements for trace detection of small molecules is raised.Therefore,it is very important to improve the detection sensitivity of SALDI-MS.To replace organic matrix with inorganic materials in SALDI-MS can overcome the interference of organic matrix in low molecular weight region.The inorganic materials used for replacing organic matrix include nanomaterials and surface nanostructures,such as gold nanoparticles and silicon nanostructures.Gold nanoparticles have the advantages of easy preparation,controllable morphology,stable chemical properties and high photothermal conversion efficiency;Silicon nanostructures have high UV absorption,low thermal conductivity and excellent electronic properties.In order to improve the detection sensitivity of SALDI-MS,the following research works were carried out based on the above two materials:I.Preparation of gold nanoparticle films as SALDI-MS substrates to improve the sensitivity of SALDI-MS detection.Gold nanoparticles have the advantages of good photothermal conversion efficiency and controllable size morphology.It was assembled into closely arranged gold nanoparticle films and immobilized on the silicon surface by sulfhydryl groups as SALDI-MS substrates.This improves the detection sensitivity.The detection limit of 1×10^-11 mol/L was achieved with this substrate for crystalline violet,which is lower than the national standard limit of 1.25×10^-9 mol/L by LC-MS.At the same time,this substrate has good reproducibility of detection.Using 1×10^-6mol/L crystalline violet as the probe molecule,the"point-to-point"relative standard deviation was≤6.90%and a"substrate-to-substrate"RSD of 9.34%.It has good linear correlation（R²≥0.9882）in the concentration range of 1×10^-9-1×10^-4 mol/L.This substrate can be applied to the analysis of verapamil hydrochloride drug in human serum.This indicates its potential for the detection of real samples.II.A"hydrophobic-hydrophilic"pattern was prepared on the surface of silicon nanocones with high absorbance.The sample was enriched,which improved the sensitivity of SALDI-MS detection.The substrate was used for the analysis of crystalline violet and arginine with detection limits as low as 1×10^-12 mol/L,lower than the national standard of 1.25×10^-9 mol/L.At the same time,the reproducibility of the assay can be improved with this substrate.The RSD of"point-to-point"with crystalline violet as the probe molecule was≤8.42%,and the RSD of"substrate-to-substrate"was 10.74%.The substrate can be used for quantitative analysis.The linear correlation was good in the concentration range of 1×10^-9-1×10^-4 mol/L（R²≥0.9846）.And the results of detecting multiple classes of small molecules（dyes,amino acids,drugs,antibiotics）show its good generalizability.It can also be used to analyze actual lake water samples containing sulfonamide antibiotics.