I am a final-year PhD candidate in Chemical Sciences at the Institute of Organic Chemistry, Lodz University of Technology (Poland), working under the supervision of Professor Beata Kolesińska. My doctoral research focuses on identifying peptide fragments of native proteins that may support the diagnosis of COVID-19. The project consists of two complementary research directions. The first involves the detection of characteristic peptide biomarkers in biological samples, particularly in patients’ exhaled breath collected on respiratory filters, as well as in lung tissue sections. The second concerns the selection of peptide fragments derived from the human angiotensin-converting enzyme 2 (hACE2), the receptor responsible for SARS-CoV-2 spike protein binding in the host cell. These peptides have the potential to be immobilized on nanogold-coated sensor surfaces for the detection of viral particles in exhaled air or in the environment.

As part of this work, I synthesized an overlapping decapeptide library covering the full primary sequence of hACE2, using the SPOT technique on a cellulose membrane and triazine-based coupling reagents. Dot-blot assays with HRP-labelled S1 subunit of the SARS-CoV-2 spike protein enabled the identification of peptide–protein complexes, including 16 fragments showing strong interactions and another 16 with moderate affinity. From these, ten fragments with the strongest signals and longest sequences were selected for detailed analysis.

Thanks to the EPS Mobility Fellowship, I had the great opportunity to undertake a second research internship at the interdepartmental research unit of Peptide and Protein Chemistry and Biology “PeptLab” at the University of Florence (Italy), led by Professor Anna Maria Papini. The established collaboration between Lodz University of Technology, the University of Florence, and the PEC laboratory, part of the R&D division at Gyros Protein Technologies, allowed me to significantly advance the investigations initiated during my first stay.

Automated synthesis of a second series of hACE2-derived peptides, combined with PEC-assisted purification, enabled the rapid preparation of a high-quality set of compounds. These peptides were subsequently analysed for their biological activity toward the trimeric SARS-CoV-2 spike protein using surface plasmon resonance (SPR) available in PeptLab. Additional information on peptide secondary structure was obtained through circular dichroism (CD) spectroscopy. Ongoing studies using microscale thermophoresis (MST) to evaluate interactions with the S1 subunit will provide complementary data essential for the completion of my doctoral dissertation.

For further background on the initial phase of this project, please refer to my earlier EPS report available at: https://www.eurpepsoc.com/aleksandra-czerchawy-report-on-the-stay-on-a-scientific-internship-under-the-eps-mobility-fellowship/