Self‐assembled‐monolayer‐modified silicon substrate to enhance the sensitivity of peptide detection for AP‐MALDI mass spectrometry

Abstract

A self-assembled-monolayer-modified silicon substrate was successfully used to enhance the sensitivity of peptide detection for atmospheric pressure-matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI/MS). The effect of surface modification of silicon wafer samples with NH(2) and OH functional groups was investigated. In addition, solvent effects for the preparation of modified NH(2)-functionalized surfaces were examined. The sensitivities for the two peptides were significantly improved, increasing between 12 and 160 times, for bradykinin and gramicidin, respectively, on an NH(2)-modified silicon surface prepared in toluene, over that on a conventional gold substrate. The limits of detection (LODs) for bradykinin and gramicidin using the conventional gold substrate in AP-MALDI/MS experiments were > 0.011 microM and 110 microM, respectively. Using our SAM approach, the LODs for bradykinin and gramicidin in AP-MALDI/MS can be improved to 0.93 nM and 0.33 microM, respectively. This SAM approach for AP-MALDI/MS is simple and sensitive, and can be used for high-throughput analysis.

Reverse micellar microextraction for rapid analysis of thiol‐containing peptides and amino acids by atmospheric‐pressure matrix‐assisted laser desorption/ionization ion trap and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry

“…AP‐MALDI MS offers several advantages such as minimal sample cleanup, ease of sample preparation, simplicity of operation and low cost. However, the disadvantages of the AP‐MALDI source are the limited sensitivity and the mass range 9, 12, 13, 22, 39. However, the sensitivity of the AP‐MALDI MS method could be increased by a suitable sample pretreatment process.…”

“…Matrix‐assisted laser desorption/ionization mass spectrometry (MALDI MS) was introduced by Karas and Hillenkamp in 1988 6. It has become a widespread, powerful and mainstream analytical tool for the analysis of biomolecules such as peptides, proteins, oligonucleotides, carbohydrates and drugs in complex mixtures 7–18. However, difficulties are encountered during the analysis of biological samples due to possible interferences arising from the constituents of real samples and this is often a serious challenge for analytical chemists.…”

Liquid‐phase microextraction for rapid AP‐MALDI and quantitation of nortriptyline in biological matrices

“…Thus, the efforts to improve the sensitivity of AP-MALDI/ MS is very important for the development of this technique. We have previously demonstrated that the use of a self-assembly monolayer (SAM) modified unetched silicon wafer can improve the sensitivity in peptide analysis for AP-MALDI/MS [26]. In this study, we also found that the micropipette extraction (MPE) technique can be used as a concentrating probe to improve the sensitivity of the AP-MALDI/MS.…”

Porous silicon affinity chips for biomarker detection by MALDI-TOF–MS

“…The PSi surface provides high specific surface area and adaptability for modification with functional groups or biomolecules to affinitively capture target biomolecules of interest. These on-chip affinity capture methods based on DIOS facilitate a fast and high-throughput platform, including purification, characterization, and quantification, which can separate and detect the target molecules from complex body fluids in one system without additional treatment [15][16][17][18][19][20]. Nowadays the onchip separation approach coupled with MALDI has been widely used in clinical proteomics, process proteomics, and research proteomics, especially in biomarker identification and disease diagnoses [13,21,22].…”