Creating a Map for Surgeons: Direct Blotting Assisted Stamping of Tissue for MALDI Imaging Mass Spectrometry
MALDI imaging mass spectrometry is an attractive technique for the discovery of disease biomarkers from surgically removed tissue sections. It can provide spatial resolution and relative abundance of a wide range of biomolecules across the tissue surface. While the technology has advanced considerably in the past decade it suffers from several drawbacks including a limited percentage of biomolecules that can be imaged, complex sample handing steps lead to loss of/or distortion of analytes, and the significant amount of time between sample harvest and analysis. To address the shortcomings of cumbersome sample preparation associated with tissue analysis, not limited to sectioning of the tissue, embedding samples, and storage we explore the development of patterned surfaces able to obtain a chemical profile of tissue via direct contact imprinting. This can yield spatial chemical information about imprinted tissue histopathology without the need for embedding, sectioning, or storage. Multiple patterned surfaces have been explored, including: C-18 and poly-lysine functionalized, laser micromachined surface energy traps (SETs), micro-biopsy needle arrays and micro-solvent extraction arrays. Micro-solvent extraction arrays have been shown to successfully image tissue surrogates and preliminary results show the ability to extract prognostic tissue material and provide accurate molecular mapping of tissue samples. Solvent micro-extraction arrays are fabricated using oleophobic coatings with SETs, also known as micro-patches, arrayed by plasma etching allowing for droplets of analytes to be confined in spatially resolved patches. Based on these findings, surface stamping and MALDI analysis can be implemented as a powerful tool for determining spatial distribution of biomarkers in vivo. This may greatly reduce analysis time and the loss/distortion of potential biomarkers.