A researcher investigates whether amino acids can inhibit the corrosion of medical implants

The photo shows a white woman with blue eyes and blonde hair. The upper part of her body is visible. She is wearing a white lab coat over a black blouse. White-spotted black sleeves of the blouse stick out from under the lab coat’s sleeves. The woman leans on a white benchtop with her right arm.

Dr Dominika Święch, photo from private archives

Working at a university provides great opportunities to thrive – says Dr Dominika Święch from the AGH UST Faculty of Foundry Engineering. In her work, she uses innovative spectroscopic methods to study modified metallic surfaces that are used to produce medical implants. She tests whether the use of amino acids as inhibitors can improve the resistance of surfaces to the corrosion process.

Dr Dominika Święch works in the Department of Chemistry and Corrosion of Metals at the AGH UST Faculty of Foundry Engineering. She carries out a project titled Spectroscopic studies in micro- and nanoscale of the corrosion process and its inhibition of the modified metallic surfaces applied in implantology in a consortium with the AGH UST, the AGH UST Academic Centre of Materials and Nanotechnology (ACMiN), and The Henryk Niewodniczański Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN). The project received funding in the amount of PLN 777,600 from the National Science Centre as part of the SONATA 15 programme (project number 2019/35/D/ST4/02703).

Implant corrosion processes

‘To produce implants, a variety of materials are used, which are to perform their designated functions over a specified time: they should exhibit specific mechanical properties (strength, wear-resistance, etc.), be biocomaptible with the human organism, and be resistant to corrosion. Most frequently, metals and their alloys are used. This is why, in my research, I am focusing on such metallic surfaces as, for instance, stainless steel and titanium. Unfortunately, contact between metal implants and body fluids results in various chemical reactions on the metallic surface that damage the implants. As a result, toxic compounds are released into the organism, which may lead to the development of various infections or cancers. On the other hand, replacing damaged implants is costly and requires complex and cumbersome medical procedures’, says Dr Dominika Święch.

The work coordinated by the AGH UST researcher aims at a better understanding of corrosion processes and finding efficient methods to inhibit them. One such way is to modify the surface of the material used in implantology using inhibitors. The materials studied are modified, for example, with nanoparticles of gold or copper, which possess potential anticorrosive and antibacterial properties. Moreover, they strengthen the spectroscopic signal during the examination of processes occrring on surfaces that are of interest to scholars. The application of the particles is supervised by Kamila Kollbek, DSc, at ACMiN which provides access to the necessary equipment.

Does tryptophan hinder corrosion?

Scientists pay special attention to amino acids. They make up proteins and peptides and perform numerous other biological functions. However, what is important from the point of view of implantology is the fact that they are non-toxic and relatively inexpensive. Moreover, as previous studies have shown, they can play the role of a corrosion inhibitor by means of adsorption, under specific conditions, onto the metallic surface.

The amino acid examined by the researchers is, for instance, tryptophan (Trp). It is not produced naturally by the human body and therefore must be obtained through the diet. This is important because this amino acid is essential for a number of processes: it constitutes a precursor of various metabolites, including serotonin (commonly known as the happiness hormone) and melatonin (responsible for the control of the sleep-wake cycle), influences the health of our skeletal system, and its residues form peptides that play a vital role in the immune system. To find out whether Trp is also a corrosion inhibitor, electrochemical studies of stainless steel were conducted under the supervision of Dr Gaetan Palumbo. An adverse environment was simulated that influences the process of implant corrosion in the human body (namely the presence of chloride and phosphate ions). Normally, depending on various factors, the process could take years, but in a laboratory it could have been significantly accelerated.

‘A portion of the research results related to the impact of Trp on the stainless steel corrosion process was published in ‘Coatings’. The article presents electrochemical and spectroscopic results that indicate that Trp, under controlled conditions, adsorbs onto the corroded stainless steel surface, resulting in improved corrosion resistance’, comments Dr Święch.

Innovative research techniques in corrosion studies

‘Research on the inhibition process uses surface-enhanced infrared absorption (SEIRA) and surface-enhanced Raman spectroscopy (SERS) techniques, which are useful tools for monitoring the process in the microscale. Additionally, techniques that combine the advantages of atomic force microscopy and spectroscopy (e.g. AFM-IR), which facilitate imaging the process in the nanoscale, are also used. Using primarily the methods of oscillatory spectroscopy in my research, with particular use of nano-spectroscopic imaging, is a novel approach in the investigation of the corrosion process and its inhibition. The research carried out with the use of the aforementioned techniques has multiple advantages, namely, the measurements are fast, the sample remains intact and does not require special preparation’, explains the researcher.

Dr Święch adds that the use of spectroscopic methods facilitates the identification of the products of corrosion and makes it possible to investigate in-situ and ex-situ the corrosion inhibition process in micro- and nanoscale (e.g., determining structural changes occurring as a result of interactions between potential inhibitors and the surface of the investigated metal samples with simultaneous surface morphology control). ‘Research in this field can result in a better understanding of corrosion processes and contribute to improving the corrosion resistance of materials used in implantology’, explains Dr Święch. She highlights that this would not have been possible if not for the consortium with IFJ PAN which provided the equipment that facilitated the broad scope of the investigation. ‘Special thanks are due to Dr hab. Czesław Paluszkiewicz, IFJ PAN Associate Professor, Dr Natalia Piergies, and Dr Ewa Pięta’.

Science that humbles

Dr Dominika Święch has been interested in research work since her secondary school years, when she competed in biological contests. Although her first steps at a university were taken at the JU Faculty of Chemistry, she never abandoned her interests in biology. This manifested itself in her doctoral dissertation which was devoted to spectroscopic studies on bradykinin and its analogues with adversarial effect on B2 receptors (Professor Edyta Proniewicz was the supervisor). Even now she stresses that her scientific growth is driven by interdisciplinary projects. ‘If we want to be competitive as scientists on a global scale, we should cooperate with one another and mutually share our specialised knowledge’, says Dr Święch.

The AGH UST researcher notes that her profession requires humility and resilience in pursuing goals: ‘There are sometimes more failures than successes. I only got the funds for my project the fourth time I applied for them. However, from the moment I first submitted it, it has evolved substantially, which allowed me to thrive and mature scientifically’.

For Dr Święch, science still remains not only work, but also passion. She skilfully reconciles it with her other obligations arising from the fact that she is a mother of two.

‘I have always liked challenges, I was always curious. Knowing how much I don’t know yet is humbling and makes my job interesting. I like its versatility: the hours spent in the laboratory, but also the processing and analyses of the data and the search for the necessary literature. A significant portion of my work at the university is also teaching students, thanks to whom I continue to develop. My work gives me so much happiness and satisfaction, although it is not always easy’.