Improving The Performance Of Surface-Enhanced Raman Spectrometry Analysis And Laser Desorption/Ionization Mass Spectrometry Analysis By Micro/Nanostructure

The trace detection of analyte molecules is an important issue in the field of analytical chemistry.Surface enhanced Raman scattering(SERS)and laser desorption/ionization mass spectrometry(LDI MS)are important methods for achieving trace detection of analyte molecules.The main contribution to SERS enhancement is from electromagnetic enhancement.The limit of detection depends on the intensity and density of hot spots,and its reproducibility depends on the distribution of hot spots and molecular distribution on the hot spots.The efficient methods for improving SERS performance include increasing the density of hot spots,and tuning the volume and location of hot spots.LDI MS mainly includes matrix assisted laser desorption ionization mass spectrometry(MALDI MS)and surface assisted laser desorption ionization mass spectrometry(SALDI MS).The reproducibility of MALDI MS is limited by coffee ring effect and heterogeneous cocrystallization between the matrix and the analyte molecules,therefore,the internal standard method is the major method for quantitative analysis in MALDI MS.Internal substance is the indispensable substance to realize the quantitative analysis,which is of the similar molecular structure and properties with the analyte molecules.However,not every analytes has the suitable internal standard substance.SALDI MS has been used for analysing small molecules because of no interference of matrix.Based on the thermal desorption mechanism in SALDI MS,researchers have developed many substrates with high absorption.However,there is few works associated with improving the efficiency of laser energy even though it plays the key role in SALDI analysis.To address the above issues,the following researches have been carried out based on the designing and fabrication of the micro-nanostructures:1.The reproducibility of SERS measurements is highly improved by using the "V" and "W" nanoarrays covered with silver film as SERS substrate,which can provide easy accessible,large area and uniformly distributed hot spots..2.The hot spots are formed by inducing the aggregation of silver nanoparticles with the capillary force of analyte solution on the created superhydrophobic substrate.This method can produce hot spots with high density,and make the analyte molecules only located on the hot spots.The trace detection can be achieved with this method.3.The quantitative analysis in MALDI MS analysis is achieved by using the prepared PMMA nanodots decorated,hydrophobic Si nanocone array as the target,which can absorb hydrophobic proteins and peptides.4.The desorption/ionization efficiency in mass analysis is improved by using the prepared superhydrophobic gold film covered silicon nanocone array as the target,which makes ananlyte molecules concentrated on the tips where the photon energy is confined.