A new laser-based probe will fire infrared pulses at tissue samples to vaporise proteins directly from their natural surroundings, capturing them in liquid droplets for mass spectrometry analysis. Proteins carry out nearly every function in the body, but studying them in their native tissue environment—where their shape and interactions with other molecules determine their behaviour—has been technically difficult. Existing methods require labelling proteins with tags, which means researchers must already know what they are looking for. The team’s native ambient mass spectrometry (NAMS) technique avoids this, but until now it has only detected abundant proteins, missing the rarer ones that often drive disease. The project adds two lasers to the mass spectrometry platform. A pulsed infrared laser improves the sampling probe, aiming to reach cellular-scale resolution. A second CO₂ laser boosts sensitivity and enables new ways to identify proteins. If successful, the next-generation NAMS platform could transform molecular pathology and drug discovery by revealing how proteins interact with drugs and other molecules directly in diseased tissue, without prior knowledge of what to look for. This is fundamental instrument development, but the ability to map low-abundance proteins in their native context could eventually improve diagnostic accuracy and accelerate target identification for new therapies.
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Proteins are a class of hugely important biomolecules. They perform all the functions necessary for life, as well as finding applications as therapeutics. To fully understand the roles of proteins in health and disease, it is necessary to understand their structure and interactions on the molecular level and, most importantly, to gain that understanding in the actual biological context, i.e., in tissue. To address that challenge, we have developed native ambient mass spectrometry (NAMS). NAMS allows the identification and spatial mapping of proteins in tissue, in addition to providing information on structure and interactions with other molecules, including proteins, drugs, small molecule ligands and metal ions. NAMS offers advantages over other spatial biology methods, such as immunohistochemistry, as there is no requirement for labelling and, consequently, no requirement for prior knowledge of a protein's identity. All proteins have a mass, therefore, in principle, all proteins can be detected by mass spectrometry. The potential of NAMS for applications in molecular pathology and drug discovery is truly exciting; however, to date, NAMS has been limited to the characterisation of proteins with higher abundance. Our recent work has focused on the development of the sampling technique nanospray desorption electrospray ionisation (nano-DESI), which offers higher spatial resolution than previous NAMS techniques for direct analysis of proteins from tissue. There is a pressing need to improve both the sensitivity and robustness of NAMS, beyond that achieved with nano-DESI, and to complement these with improved confidence in protein identifications. The aim of this proposal is to realise these required improvements through scientific instrument development, specifically by the integration of lasers with the existing mass spectrometry platform. The first development focuses on the protein sampling device. A new NAMS probe that couples laser desorption, via a pulsed infrared laser, with liquid microdroplet capture of biological material and subsequent ionisation, will be designed, constructed, and validated. The new probe will address the challenge of robustness and advance NAMS towards cellular resolution protein imaging. The second development will integrate a CO2 infrared laser with the mass spectrometer which will improve sensitivity and augment the system with new techniques for protein identification. Together, these modifications will comprise the step-change required to deliver next-generation NAMS and realise its potential to transform life science research.
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