3 years ago

Thermoresponsive Arrays Patterned via Photoclick Chemistry: Smart MALDI Plate for Protein Digest Enrichment, Desalting, and Direct MS Analysis

Thermoresponsive
Arrays Patterned via Photoclick Chemistry: Smart MALDI Plate for Protein
Digest Enrichment, Desalting, and Direct MS Analysis
Huangxian Ju, Quan Cheng, Zhicong Chao, Junjie Hu, Ying Liu, Xiao Meng
Sample desalting and concentration are crucial steps before matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) analysis. Current sample pretreatment approaches require tedious fabrication and operation procedures, which are unamenable to high-throughput analysis and also result in sample loss. Here, we report the development of a smart MALDI substrate for on-plate desalting, enrichment, and direct MS analysis of protein digests based on thermoresponsive, hydrophilic/hydrophobic transition of surface-grafted poly(N-isopropylacrylamide) (PNIPAM) microarrays. Superhydrophilic 1-thioglycerol microwells are first constructed on alkyne–silane-functionalized rough indium tin oxide substrates based on two sequential thiol-yne photoclick reactions, whereas the surrounding regions are modified with hydrophobic 1H,1H,2H,2H-perfluorodecanethiol. Surface-initiated atom-transfer radical polymerization is then triggered in microwells to form PNIPAM arrays, which facilitate sample loading and enrichment of protein digests by concentrating large-volume samples into small dots and achieving on-plate desalting through PNIPAM configuration change at elevated temperature. The smart MALDI plate shows high performance for mass spectrometric analysis of cytochrome c and neurotensin in the presence of 1 M urea and 100 mM NaHCO3, as well as improved detection sensitivity and high sequence coverage for α-casein and cytochrome c digests in femtomole range. The work presents a versatile sample pretreatment platform with great potential for proteomic research.

Publisher URL: http://dx.doi.org/10.1021/acsami.7b13640

DOI: 10.1021/acsami.7b13640

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