title: Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation.
abstract: This work demonstrates a method to prepare homogeneous distributions of analytes to improve data reproducibility in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Natural-air drying processes normally result in unwanted heterogeneous spatial distributions of analytes in MALDI crystals and make quantitative analysis difficult. This study demonstrates that inducing Marangoni flows within drying droplets can significantly reduce the heterogeneity problem. The Marangoni flows are accelerated by changing substrate temperatures to create temperature gradients across droplets. Such hydrodynamic flows are analyzed semi-empirically. Using imaging mass spectrometry, changes of heterogeneity of molecules with the change of substrate temperature during drying processes are demonstrated. The observed heterogeneities of the biomolecules reduce as predicted Marangoni velocities increase. In comparison to conventional methods, drying droplets on a 5 °C substrate while keeping the surroundings at ambient conditions typically reduces the heterogeneity of biomolecular ions by 65%-80%. The observation suggests that decreasing substrate temperature during droplet drying processes is a simple and effective means to reduce analyte heterogeneity for quantitative applications. Graphical Abstract ᅟ.
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.
authors.forename: Yin-Hung
authors.initials: YH
authors.lastname: Lai
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.
authors.forename: Yi-Hong
authors.initials: YH
authors.lastname: Cai
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.
authors.forename: Hsun
authors.initials: H
authors.lastname: Lee
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.|Chemistry Department, National Taiwan University, Taipei, 106, Taiwan, Republic of China.
authors.forename: Yu-Meng
authors.initials: YM
authors.lastname: Ou
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.
authors.forename: Chih-Hao
authors.initials: CH
authors.lastname: Hsiao
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.|Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, 106, Taiwan, Republic of China.
authors.forename: Chien-Wei
authors.initials: CW
authors.lastname: Tsao
authors.affiliation: Chemistry Department, National Taiwan University, Taipei, 106, Taiwan, Republic of China.
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China. wer@gate.sinica.edu.tw.
authors.forename: Yi-Sheng
authors.initials: YS
authors.lastname: Wang
keywords: Heterogeneity; Hydrodynamic flow; MALDI; Marangoni flow; Sample preparation; Spatial distribution; Substrate temperature