Simultaneous Analysis of Multiple Cancer Biomarkers Using MALDI-TOF Mass Spectrometry Based on a Parylene-Matrix Chip

Abstract

Recently, the parylene-matrix chip was developed for quantitative analysis of small molecules less than 1 kDa. In this study, MALDI-TOF MS based on the parylene-matrix chip was performed to clinically diagnose intrahepatic cholangiocarcinoma (IHCC) and colorectal cancer (CRC). The parylene-matrix chip was applied for the detection of small cancer biomarkers, including N-methyl-2-pyridone-5-carboxamide (2PY), glutamine, lysophosphatidylcholine (LPC) 16:0, and LPC 18:0. The feasibility of MALDI-TOF MS based on the parylene-matrix chip was confirmed via analysis of spot-to-spot and shot-to-shot reproducibility. Serum metabolite markers of IHCC, N-methyl-2-pyridone-5-carboxamide (2PY), and glutamine were quantified using MALDI-TOF MS based on the parylene-matrix chip. For clinical diagnosis of CRC, two water-insoluble (barely soluble) biomarkers, lysophosphatidylcholine (LPC) 16:0 and LPC 18:0, were quantified. Finally, glutamine and LPC 16:0 were simultaneously detected at a range of concentrations in sera from colon cancer patients using the parylene-matrix chip. Thus, this method yielded high-throughput detection of cancer biomarkers for the mixture samples of water-soluble analytes (2PY and glutamine) and water-insoluble analytes (LPC 16:0 and LPC 18:0).

An Updated Review of Pro- and Anti-Inflammatory Properties of Plasma Lysophosphatidylcholines in the Vascular System

“…Furthermore, a prospective metabolomics study discovered that higher levels of saturated LPC 18:0 reduced the risk of most common cancers [ 155 ], while higher levels of 8 different LPCs correlated with lower risk of advanced stage prostate cancer [ 156 ]. To enable high-throughput and quantitative analysis of LPCs as cancer biomarkers a novel parylene matrix biochip was recently developed and validated for clinical diagnosis [ 157 ].…”

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

“…Typically, matrices are known to be fragmented when they are exposed to laser radiation . When organic matrices such as CHCA were used as a sample for MALDI-ToF mass spectrometry (Case 2 in Figure b), there were unreproducible mass peaks at the low m / z ratio of less than 500, as in the previous works . Therefore, the mass peaks of amino acids in the molecular weight range 100–200 Da were difficult to isolate from the mass peaks of fragmented matrix molecules.…”

“…The relative standard deviation (RSD = m/σ × 100 in %) and the reproducibility (%) were calculated to be 100-RSD. 9 As shown in Figure 4a, the spot-to-spot reproducibility was estimated at five independent sample spots to be 61.5% for conventional MALDI-ToF mass spectrometry and 96.0% for LDI-ToF mass spectrometry. The mass spectrum for the reproducibility calculation is presented in Supporting Information (Figure S4a).…”

“…43 When organic matrices such as CHCA were used as a sample for MALDI-ToF mass spectrometry (Case 2 in Figure 1b), there were unreproducible mass peaks at the low m/z ratio of less than 500, as in the previous works. 9 Therefore, the mass peaks of amino acids in the molecular weight range 100−200 Da were difficult to isolate from the mass peaks of fragmented matrix molecules. Individually, when SiO 2 aerogel was used as the sample for LDI-ToF mass spectrometry (Case 3 in Figure 1b), no mass peak was detected as the aerogel itself was not ionized and desorbed by laser radiation.…”

“…The fragmented matrix molecules produce mass peaks in the low m / z range of less than 500 Da, as shown in Figure a. Because of this, MALDI-ToF MS measurements of small molecules with a molecular weight of less than 500 Da are limited. − As the measurement with MALDI-ToF MS is carried out after drying the sample on a target plate, the analyte crystal is usually an inhomogeneous shape and the intensity of mass peaks from the analyte crystal vary according to the position of laser radiation, even for the sample spot at identical concentrations. − Therefore, quantitative measurement has been limited for conventional MALDI-ToF MS. After Siuzdak et al reported porous silicon as an inorganic matrix for MALDI-ToF MS, many research groups have tried to develop matrices based on inorganic materials to replace the organic matrices. This method has been called laser desorption/ionization mass spectrometry (LDI-MS) .…”