Vincentas Mindaugas Mačiulis, a chemist od the Department of Nanotechnologies at FTMC, has defended his PhD thesis on "Application of Metallic and Metal Oxides Nanostructures for Proteins Bionsensing by Ellipsometry and Quartz Crystal Microbalance" (academic supervisor: Dr. Ieva Plikusienė).

 

Congratulations to the new PhD, we wish you inspiration and success!

 

The COVID-19 pandemic is over, we have learnt a lot of lessons and we can feel quite safe now. But, according to Vincentas, science cannot stand still: "New variants of the virus are emerging, against which we need to test our immunity and assess whether I am still protected from having received the vaccine or having been ill. Sensors are important for this purpose," says the chemist.

 

To make biosensors more sensitive, the scientist has been studying the feasibility of applying nanostructures - microscopic particles created in the lab - to them.

 

"We looked at the ability of porous alumina to accumulate protein molecules in nanopores on its surface, using human serum albumin [a protein that carries a variety of beneficial substances around the body]. We have also analyzed the potential impact of zinc oxide nanowire surfaces to enhance the optical signal response in biosensor applications," says Vincentas.

 

 

 

According to the expert, a large number of experiments were needed to understand whether the desired nanostructures could be applied to biosensors:

 

"In our studies, we look at how proteins bind (whether it is by sticking to a surface or by the interaction between two proteins forming a complex). This required sensitive techniques. One of them is spectral ellipsometry. This is an optical technique in which we observe changes in the light reflected from a sample.

 

Another technique is quartz crystal microballance with dissipation, which is basically a very small and sensitive "scales" that also works in water, which is very useful for us when we want to analyze the interaction of biological molecules."

 

What new insights have these biosensor studies revealed? "During the COVID-19 pandemic, we analyzed the interaction of the SARS-CoV-2 spike protein with antibodies in our blood. Our method shows that the antibodies formed in our body after a single dose of the Vaxzevria vaccine can form a strong immune complex not only with the primary SARS-CoV-2 spike protein, but also with the Alpha and Beta variants.

 

At the same time, the interaction of another important protein of the SARS-CoV-2 virus, the nucleocapsid, with specific antibodies has been studied. The results show that the flexibility of the specific antibodies is an important factor in the interaction with the small-sized SARS-CoV-2 nucleocapsid proteins," says the researcher.