Biomolecules are usually labelled with fluorescent substances - enzymes or nanoparticles - so that interactions can be captured and observed. These tracers act as special intermediaries between the event (the interaction between biomolecules) and the recorder (the method to spot the interaction). These intermediaries usually require additional cost and time. Therefore, the technology under development partly reduces the cost of sensors and environmental pollution by not using chemically active materials (nanoparticles, dyes) in the analysis.

 

The new sensor is very important for the healthcare and veterinary as a tool for the evaluation of the presence of the numerous disease biomarkers on a single chip and can be potentially used for the prediction of the compatibility of transplant organs between donors and recipients.

 

This year in between November 25 and 27 the FTMC had the honor of hosting Dr. Lyudmila Shmelova from the Theoretical Physics Department of the Taras Shevchenko National University of Kyiv. Dr. Shmelova is a specialist in laser radiation interactions with substance surfaces. Her visit was under the Lithuanian–Ukrainian cooperation programme in the fields of Research and Technologies. The joined project entitled "Development of a New Cost-Effective Optical Sensor for Label-Free Monitoring of Specific Biomolecule Interactions".

 

 

 

International cooperation is initiated for the improvement of a common Surface Plasmon Resonance (SPR) method for the investigation of the biomolecule interactions. The SPR technique, established at the end of the 20th century, is renowned for its precision in monitoring biomolecule interactions without specific labels. While it has become a gold standard in drug testing, SPR setups traditionally require bulky expensive equipment and meticulously adjusted microfluidic operations.

 

"Classic SPR approaches use gold-coated glass chips, which are costly and challenging to handle. Various laboratories are working on improvements of this method. Our improvement enables real-time observation of sensor chip areas during investigation," explains Dr Edita Voitechovič, a researcher at the FTMC Department of Nanoengineering.

 

This approach offers several advantages, including:

 

1. Measuring angles of the ellipsometer components instead of light flux, which helps mitigate issues related to light source stability and detector non-linearity.

 

2. Allowing precise quantitative analysis of molecules adhered to the chip surface, as opposed to recording relative units or shades of grey.

 

The primary output of these measurements is the change in Delta and Psi angles of elliptically polarized light, derived from the angles of ellipsometer components (polarizer, compensator, and analyser) after the light interacts with the sample surface at a specific laser angle of incidence (AOI).

 

The tasks of current projects are devoted to the improvement of the classical approach of the null-ellipsometry for the investigations of biomolecule interactions for the monitoring of diverse sizes of the molecules and their complexes at the same time on the same sensor surface.

 

 

 

The Ukrainian team involved in the project includes Dr Lyudmila Shmelova, Prof Viktor Reshetnyak, Dr Anatoly Suprun, and Master’s student Sofiya Ivanchuk. Their tasks are to model coatings for an innovative optical sensor chip and help process obtained results.

 

While the Lithuanian team is comprised of FTMC members from the Department of Laser Technologies head of the project Dr. Alexandr Belosludtsev, the PhD student Ignas Bitinaitis and the Department of Nanoengineering Dr. Edita Voitechovič, and Tomas Rakickas. The FTMC team are working under manufacturing and practical implementation of the theoretically modelled sensor chips and testing them for the application in the investigations of biomolecule interactions.

 

"The first year of the project yielded several notable achievements. It was suggested and practically realized various optical coatings for sensor chips. These new sensors demonstrated significantly improved mechanical properties for handling and surface regeneration compared to conventional gold-coated glass slides," says Dr A. Belosludtsev, head of the project.

 

Moreover, these findings indicate that the new optical sensor can monitor biomolecule complexes up to 80 nm, maintaining a linear relationship between the observed Delta angle and the optical thickness of the protein complexes. This is a significant advancement for the development of label-free protein microchips used for extensive biomarker screening. Such protein microchips are particularly useful in investigating complex diseases, like chronic and metabolic conditions, that involve changes in more than two protein biomarkers.