Direct Analysis of Human Sputum for Differentiating Non-small Cell Lung Cancer by Neutral Desorption Extractive Electrospray Ionization Mass Spectrometry

Abstract

Human sputum, a typical highly viscous biosample, was directly characterized at the molecular level using neutral desorption extractive electrospray ionization mass spectrometry (ND-EESI-MS) without multi-step sample pretreatment, in an attempt to provide a method for constructing the pattern recognition of rapid diagnosis of lung cancer. Under the optimal experiment conditions, glucose, amino acids, phosphoric lipids and other typical analytes in the sputum sample could be used to conduct qualitative or quantitative (in arginine) analysis. More interestingly, the full scan mass spectra from 50 patients of non-small cell lung cancer, recording the mass spectral fingerprints of sputum samples, were differentiated from the control group (50 healthy individuals) through principal component analysis (PCA). These findings suggest that valuable molecular information concealed in human sputum could be easily revealed and applied for conducting qualitative or quantitative analysis by direct ND-EESI-MS analysis.

Neutral Desorption Extractive Electrospray Ionization Mass Spectrometry Analysis Sputum for Non-Invasive Lung Adenocarcinoma Detection

“…The sample preparation protocol was modeled after previous studies. 17 , 18 Sputum samples, stored at −80°C, were first thawed at 4°C overnight prior to MS analysis. After samples were vortexed for 5 s, a 1 mL aliquot of sputum was set to a sealed glass vial ( Figure S1 ) without any other pretreatment.…”

“…This sample was used for quality control (QC) purposes and was analyzed once every 10 study samples for NS-EESI-MS analysis. 18 …”

“…This is crucial especially for small tumors, or for tumors in early stage. Sputum contains thousands of compounds including fatty acid amide, cytoglobin, 16 palmitoleic acid, putrescine, phosphatidylcholines, 17 , 18 and diethyl glutamate cysteamine, 12 etc. Developments in ambient mass spectrometry (AMS) 19–22 examinations are now able to identify extremely small metabolites alterations from sputum, typical highly viscous bio-sample, using neutral desorption extractive electrospray ionization mass spectrometry (ND-EESI-MS) without multi-step sample pretreatment.…”

“…Developments in ambient mass spectrometry (AMS) 19–22 examinations are now able to identify extremely small metabolites alterations from sputum, typical highly viscous bio-sample, using neutral desorption extractive electrospray ionization mass spectrometry (ND-EESI-MS) without multi-step sample pretreatment. 18 In our previous study of ND-EESI-MS, an AMS metabolic profiling approach was used for the identification of candidate NSCLC metabolic markers. Altered phosphatidylcholines in sputum were shown to be effective for the detection of NSCLC.…”

Chemometrics and Related Fields in Python

“…Many open source projects in Python have been adequately developed and distributed via GitHub, 8,9 e.g., a scikit-learn (sklearn) machine learning (ML) library for Python. [10][11][12] This library fortunately contains many typical tools for multivariate analysis 13,14 and chemometrics, [15][16][17][18] e.g., principal component analysis (PCA), [19][20][21][22][23] partial least squares (PLS), [24][25][26][27][28][29] etc. Other chemometrics tools that are not included in the ML library, e.g., pyMCR 30, 31 for multivariate curve resolution (MCR), [32][33][34][35][36][37] are also independently found in GitHub.…”