Efficient and Cost-Effective Enzyme Deposition onto Tissues for Mass Spectrometry Imaging of N-Glycans Using a Mini-Humidifier

Mass spectrometry imaging (MSI) is a powerful technique for studying the spatial localization of N-linked glycans in biological tissues, which are important biomarkers for various diseases. Analyzing N-linked glycans requires the deposition of an enzyme onto a biological tissue section to release them from proteins. However, existing equipment for enzyme deposition is relatively expensive and may not be readily accessible to some laboratories. To address this challenge, we developed and evaluated a cost-effective approach for enzyme application onto tissue sections using a mini-humidifier. We demonstrate the capabilities of this approach by applying peptide N-glycosidase F (PNGase F) for MSI of N-linked glycans present within mouse brain tissue sections using nanospray desorption electrospray ionization (nano-DESI). The performance of the mini-humidifier was comparable to that of a widely used HTX-TM Sprayer, establishing it as a cost-effective and efficient alternative for enzyme deposition onto tissue samples in MSI experiments. This work offers an accessible approach for enzyme application on biological samples to study the spatial distribution of N-linked glycans using MSI.