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Protein ion yield enhancement in matrix‐assisted laser desorption/ionization mass spectrometry after sample and matrix low‐pressure glow discharge plasma irradiation
Author(s) -
Hajiani Shahedeh,
Ghassempour Alireza,
Shokri Babak
Publication year - 2020
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8964
Subject(s) - chemistry , analyte , mass spectrometry , matrix assisted laser desorption/ionization , analytical chemistry (journal) , matrix (chemical analysis) , desorption , chromatography , organic chemistry , adsorption
Rationale Plasma‐assisted ionization is widely used in mass spectrometry; in this study, a low‐pressure glow discharge is introduced as a new method to improve the detection of large proteins, and bovine serum albumin (BSA) is used as a protein model. The treatment of analyte, matrix, and the matrix/analyte mixture is evaluated under optimal conditions. Methods Low‐pressure radio‐frequency capacitively coupled plasma (RF‐CCP) treatment is utilized in the sample preparation step of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) to enhance the protein MALDI ion signal. Plasma treatment can be an effective tool for enhancing the non‐covalent binding of the analyte with the matrix, incorporation of the analyte into the matrix, production of matrix/analyte crystals, and analyte protonation through plasma activation, resulting in an improved MALDI ion signal. Results Fourier‐transform infrared (FTIR) spectroscopy allows us to distinguish between the functional groups of plasma‐treated and control samples. In addition, optical emission spectroscopy (OES) determines the plasma species, and zeta potential analysis characterizes the potential difference between plasma‐treated and control samples before MALDI‐TOF MS analysis. Plasma‐treated BSA can provide a five‐times enhancement of ion intensity. The combination of the plasma‐treated analyte with the plasma‐treated matrix leads to an increase in the ion intensity by a factor of 14. Conclusions Low‐pressure glow discharge plasma treatment greatly enhances MALDI ion signals, with a noticeable increase in incorporation, co‐crystallization, protonation, and the concentration of the sample functional groups.