Optimization and Method Development of Pneumatically Sprayed AuNPs for Laser-Desorption Ionization Mass Spectrometry Imaging

Matrix assisted laser desorption ionization mass spectrometry MALDI-MS has previously been ineffective at identifying compounds in the low mass range (below 500 Da).Citrate-capped gold nanoparticles (AuNPs) have been demonstrated as a suitable alternative for LDI mass spectrometry imaging (MSI) for small molecules. Currently, AuNPs are applied as a novel material in mass spectrometry imaging (MSI) projects. AuNPs sprayed onto tissue samples have the following advantages: (i) greater analyte ionization with less background chemical noise, (ii) near elimination of signal delocalization, (iii) increased lateral spatial resolution, (iv) increased sample preparation speed, (v) and lower cost of sample preparation. Further experimentation on the flexibility of AuNPs have shown that they (i) can tolerate multiple varying spraying temperatures and velocities, (ii) can be applied to a sample and then be stored frozen or under vacuum overnight with negligible effects on ionization, (iii) can provide ionization with a minimal spraying protocol, and (iv) a variety of sizes and manufacturers of AuNPs are feasible for MSI. The goal of this project is to help extend this technique to nonexpert users and help make biological/clinical applications and analyses more accessible for biomedical research