During the COVID-19 pandemic, pharmaceutical companies produced an unprecedented influx of vaccines, aimed at protecting global populations. While this response saved countless lives, a significant number of these vaccines remained unused, ultimately expiring and necessitating disposal. In light of this waste, researchers at the Center for Physical Sciences and Technology (FTMC) in Lithuania are investigating a novel approach to repurpose expired vaccines for the development of new biosensors.

The Role of Virus-Like Particles

The FTMC scientists, including lead author Dr. Vincentas Mindaugas Mačiulis, focused on utilizing vaccines that contain virus-like particles (VLP). VLPs mirror real viruses but lack genetic material, rendering them incapable of causing infection. However, the immune system recognizes these particles as potential threats, triggering an antibody production response. This innovative utilization of expired VLP vaccines offers an exciting avenue for creating biosensors that assess immunity to the coronavirus.

Research Objectives

The Lithuanian team outlined two primary objectives:

  • To leverage expired COVID-19 VLP vaccines.
  • To adapt these vaccines into biosensors capable of determining immunity against SARS-CoV-2.

Notably, the expired vaccines used in this research were sourced from the laboratory of Dr. Aurelija Žvirblienė at the Life Sciences Center of Vilnius University (VU GMC).

"We focused our attention on the vaccines with virus-like particles (VLP). VLPs are protein structures that resemble real viruses but do not contain their genetic material." – Dr. Vincentas Mindaugas Mačiulis

Processing Expired Vaccines

The research team took caution to purify the spike proteins from the expired vaccines which included not just the desired proteins, but also additional pharmaceutical components that stabilize the formulation. Dr. Asta Lučiūnaitė, who played a crucial role in this purification process, examined whether the isolated spike proteins retained their functional capacity by interacting with antibodies.

Methodology of the Sensor Development

In the following stages, the researchers immobilized the isolated spike proteins onto a gold surface through chemical bonding. This novel sensor was designed to detect antibodies present in blood sera. The study utilized sera from individuals with varying antibody levels, employing three distinct sensor surfaces:

  1. Isolated spike proteins from expired vaccines.
  2. Commercially available spike proteins from the original virus strain.
  3. Spike proteins from the omicron variant of the coronavirus.

Initial Findings

The initial experiments yielded promising results, with the biosensors accurately recognizing antibodies using spike proteins derived from expired vaccines. While the detection accuracy was not yet comparable to that of commercial proteins, the findings indicate substantial potential for using expired vaccines in this new context.

Environmental and Economic Benefits

The advantages of this approach transcend the immediate application. By repurposing expired vaccines, the team contributes to environmental sustainability and reduces reliance on costly commercial proteins. According to Dr. Mačiulis:

"If we succeed in refining our method into biosensor technology, it will represent a much cheaper alternative for detecting specific antibodies. Laboratories could utilize expired vaccines at a fraction of the cost."

Future Research Directions

Encouraged by their preliminary success, the FTMC team intends to expand their experiments and explore the use of the method for other vaccines beyond COVID-19. Potential applications may include VLP vaccines for diseases such as:

  • Human Papillomavirus (HPV)
  • Hepatitis B

The possibility of adapting this methodology provides a pathway for more sustainable and cost-effective disease prevention. As stated by Dr. Mačiulis:

"It is likely that the method would work in a very similar way, but we would need to ensure consistent results across various applications."

Conclusion

The repurposing of unused COVID-19 vaccines for biosensor development represents a significant stride towards sustainable science and innovative healthcare solutions. By turning waste into a valuable resource, researchers are paving the way for future methodologies that may improve our understanding and monitoring of immune responses across various infectious diseases.

References

[1] Vincentas Maciulis et al, The second life for unused COVID-19 vaccines: Towards biosensing application, Talanta (2025).

[2] Retrieved August 12, 2025, from Phys.org