Laser-Assisted Desorption/Ionization Mass Spectrometry Using Nanoporous SiO₂ Aerogels for the Diagnosis of Colon Cancer

Abstract

The SiO2 aerogel has a porous network of spherical silica particles with an average size of 3–5 nm, which provides an extremely high surface area. Herein, SiO2 aerogel was synthesized using the sol–gel method with sodium silicate as a precursor, and the SiO2 aerogel was applied to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) as an inorganic matrix for quantitative analysis. In this work, a combi-matrix was prepared by mixing the SiO2 aerogel and a conventional organic matrix (CHCA) for quantitative analysis of analytes at an m/z ratio of less than 500. Using the combi-matrix based on the SiO2 aerogel with an extremely high porosity, analyte ionization was performed without the mass peaks of the organic matrix (CHCA) for MALDI-MS. The optimal ratio between the SiO2 aerogel and the organic matrix was determined to eliminate the mass peaks from the organic matrix and maximize the signal-to-noise ratio (S/N ratio) of the analytes. Quantitative analysis was performed using the optimal combi-matrix system (a mixture of SiO2 aerogel and organic matrix (CHCA)). The homogeneous and dense distribution of analytes was demonstrated using fluorescence imaging, and the spot-to-spot and shot-to-shot reproducibility was estimated using the SiO2 aerogel. Finally, LDI-MS based on the combi-matrix was applied for the quantitative analysis of a biomarker for colon cancer, dodecanoyl-l-carnitine (DC). Using real samples from healthy volunteers and patients, a medical diagnosis of colon cancer was demonstrated using a combi-matrix.

Combi-Matrix Based on TiO2 Aerogel for Diagnosis of Sepsis Using Laser Desorption and Ionization Mass Spectrometry

“…The combi-matrix represents matrices for LDI-MS by combining different types of matrices to enhance the ionization and desorption activity. , As previously reported, SiO 2 aerogel in combination with a conventional organic matrix, CHCA, could significantly enhance the ionization efficiency for LDI-MS by supplying nanocrystalline CHCA particles with homogeneous distribution based on the nanoporous scaffold structure of the SiO 2 aerogel . As shown in Figure a, the SiO 2 aerogel itself has no photocatalytic activity for analyte ionization.…”

“…The SiO 2 aerogel for the control group was synthesized via a two-step sol–gel method with ambient pressure drying as previously reported. , The sodium silicate (5.90 mL) and DW (31.5 mL) were mixed with stirring for 5 min. Hydrolysis was conducted by adding 1 M ammonium fluoride (5 mL) and additional stirring for 4 h. Condensation of the hydrosol was performed by adding 4 M sulfuric acid (11 mL).…”

“…Furthermore, scaffold networks based on TiO 2 do not ablate although they may be deformed. The networks in aerogel also can secure the quantitative analysis by inducing a homogeneous distribution of analytes with small precipitate sizes . Therefore, in this study, the TiO 2 aerogel was selected as an LDI-MS solid-state matrix that can improve conventional MALDI-ToF MS.…”

Designed Nanomaterials‐Assisted Proteomics and Metabolomics Analysis for In Vitro Diagnosis

“…[98] Yun et al proposed the SiO 2 aerogel with a porous network of spherical silica particles as an inorganic matrix for the quantitative analysis of a colon cancer biomarker to achieve the medical diagnosis of colon cancer. [99] Pan et al designed multilayered gold-nanoparticle thin film (MTF-AuNPs) to detect bone biomarkers in the osteoporosis risk assessment. Based on the superior UV absorption, low heat capacity, and superior thermal conductivity of MTF-AuNPs, the nanomaterials can detect bone biomarkers using MALDI-MS technology with excellent signal sensitivity and reproducibility.…”

“…proposed the SiO 2 aerogel with a porous network of spherical silica particles as an inorganic matrix for the quantitative analysis of a colon cancer biomarker to achieve the medical diagnosis of colon cancer. [ 99 ] Pan et al. designed multilayered gold‐nanoparticle thin film (MTF‐AuNPs) to detect bone biomarkers in the osteoporosis risk assessment.…”