The capture of proteins in complex samples using molecular imprinting biopolymer chemistry in the field of proteomics

Cardiovascular disease is the number one cause of death globally, leading to high proportion of premature deaths. Since there is an aging population, the economic burden on health care systems increasingly requires the discovery of new biomarkers. Plasma proteomics is an approach to identify novel biomarkers using plasma. However, there are limitations with plasma due to the complexity and dynamic range between high abundant and low abundant proteins.

Approaches of overcoming complexity and dynamic range include Molecular imprinting which is a promising tool in the field of proteomics. This thesis has created an imprint using polystyrene as substrate, which can be used to enrich albumin specifically with polymerised dopamine offering huge advantages such as polymerisation in the presence of urea. Dopamine does not require complex chemicals, scalable, cheap and biodegradable. Mouse heart organ was also used to create imprints to heart proteins onto polystyrene coated with polydopamine.

Mass spectrometry was used to analyse proteins enriched from human plasma. A Nano-LC system was coupled to an Orbitrap (Q-Exactive) providing both quantitative and qualitative data. Both shotgun and targeted proteomics were employed. The Q-Exactive was operated using parallel reaction monitoring which utilises the high resolution capability of the Q-Exactive to quantitatively target peptides of proteins. Shotgun proteomics using data dependent acquisition was also employed to assess all proteins involved in the imprinting and enrichment. Extracts from molecular imprints (MIPs) contacted with plasma and their respective non-imprint controls (NIPs) were analysed using mass spectrometry. Results from mouse organ MIP contacted with plasma from five myocardial infarction patients, showed the presence of: Troponin, Fatty acid binding protein 3, Creatine Kinase, Lactate Dehydrogenase, Cardiac myosin binding protein C.

The imprint created from tissue and organ shows the potential to analyse other tissue and organ MIPs to specifically study organ damage in other diseases, for example kidney, liver and lung injury related to COVID-19 and the effects of COVID-19 on organs.