AuNPs/CNC Nanocomposite with A “Dual Dispersion” Effect for LDI‐TOF MS Analysis of Intact Proteins in NSCLC Serum Exosomes

Abstract Detecting exosomal markers using laser desorption/ionization time‐of‐flight mass spectrometry (LDI‐TOF MS) is a novel approach for examining liquid biopsies of non‐small cell lung cancer (NSCLC) samples. However, LDI‐TOF MS is limited by low sensitivity and poor reproducibility when analyzing intact proteins directly. In this report, gold nanoparticles/cellulose nanocrystals (AuNPs/CNC) is introduced as the matrix for direct analysis of intact proteins in NSCLC serum exosomes. AuNPs/CNC with “dual dispersion” effects dispersed and stabilized AuNPs and improved ion inhibition effects caused by protein aggregation. These features increased the signal‐to‐noise ratio of [M+H] + peaks by two orders of magnitude and lowered the detection limit of intact proteins to 0.01 mg mL –1 . The coefficient of variation with or without AuNPs/CNC is measured as 10.2% and 32.5%, respectively. The excellent reproducibility yielded a linear relationship ( y = 15.41 x – 7.983, R 2 = 0.989) over the protein concentration range of 0.01 to 20 mg mL –1 . Finally, AuNPs/CNC‐assisted LDI‐TOF MS provides clinically relevant fingerprint information of exosomal proteins in NSCLC serum, and characteristic proteins S100 calcium‐binding protein A10, Urokinase plasminogen activator surface receptor, Plasma protease C1 inhibitor, Tyrosine‐protein kinase Fgr and Mannose‐binding lectin associated serine protease 2 represented excellent predictive biomarkers of NSCLC risk.