Table 2.
Technical advances in sample preparation of microbial MALDI-MSI.
| Time | Introduced Technique | Advantage | Reference |
|---|---|---|---|
| 2012 | A common protocol for agar-based microbial MALDI-MSI | The first protocol for agar-based microbial MALDI-MSI | [61] |
| 2013 | A method for visible three-dimensional (3D) models of a microbial colony | Captures the depth profile of metabolite distribution beyond 2D-MALDI-MSI | [63] |
| 2014 | A method with solid MALDI matrix deposition on microbial agar culture | Enhanced signals of some fungal metabolites | [64] |
| 2015 | A method for spraying matrix solution programmatically on dried agar-based samples | Forms a homogeneous, evenly closed matrix layer | [65] |
| 2016 | A robotic matrix sprayer with a heated capillary | Higher sensitivity and lateral resolution for the analyte and suitable for different kinds of matrix | [66] |
| 2016 | A one-step matrix spraying method with optimized homemade equipment | Simplified sample preparation and high-resolved images | [67] |
| 2019 | A membrane-based culturing workflow | Offers a safe and flat microbial sample surface | [68] |
| 2022 | A method using 2,5-dihydroxybenzoic acid (DHB) as “glue” to adhere the microbial culture agar plate to the MALDI target | Prevents the sample flaking from the target under vacuum and also provides a larger area for MALDI-MSI analysis | [35] |
Note: MALDI: matrix-assisted laser desorption/ionization; MSI: mass spectrometry imaging.