Proteins naturally present in biological samples are extremely important in medical research and their presence, absence or dysregulation can act as a marker of disease. Broadly, two approaches exist for analysis by mass spectrometry. ‘Top-down’ aims to analyse native proteins whole whilst ‘Bottom-up’ typically uses chemical or enzymatic digestions to break bonds and generate smaller peptides for mass spectrometry analysis.
Mass spectrometry imaging (MSI) – incorporating techniques such as MALDI, DESI and LD-REIMS – can provide powerful, untargeted insight into the chemical makeup of biological tissues and cells. In MSI, both “top-down” and “bottom-up” approaches can be limited by several drawbacks. The dynamic range of the proteome can limit top-down proteomic analysis, where multiple different proteins of vastly differing mass and concentration are present. In contrast, the use of liquid-phase enzyme solutions to digest samples in bottom-up approaches can delocalise analytes, bottlenecking image resolution.
Approaches which can digest samples without enzymatic/liquid reagents can conserve the resolution of typical MSI, whilst overcoming the difficulties in dynamic range typically associated with top-down proteomics.
The invention uses electrical current to generate a cold argon plasma, which can then be directed through a needle to generate a corona discharge. This discharge can be used to digest condensed phase samples for subsequent analysis using MSI. Digestion products include ‘classical’ abc-xyz peptide fragments, with a proposed mechanism that is more heavily reliant on free-electron or radical mediated reactions.
This invention has been applied to detect the presence/absence of a known protein in a cell lysate sample, with good success. We have also been able to detect protein which has been spiked on to biological tissue samples in a selective manner, depending on the exposure to our argon plasma digestion.
In addition to the spiked tissue samples, cell lysates known to express/not express a protein (mNeonGreen), have been proven to be selectively detected using the invention.
Publications: TBC
Patent Status: PCT filed
Opportunity: Commercial license or co-development
For enquiries, please reference: RFI_IP_1010
