04.10.2024

A team of researchers from the University of Freiburg and the INM - Leibniz Institute for New Materials has developed a bio-based test procedure that can diagnose complex diseases simply and cheaply. These "OptoAssays" use light control to move biomolecules and read out results without mechanical support - with potential applications in on-site diagnostics.

Image: A hand pressing a light switch with its finger, all in red; Copyright: Lars Knaack/INM

Light on - light off: The test result is here.

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Early detection through digital twins

Technical developments based on biological principles are successful in many areas - from Velcro fasteners to solar cells. Researchers are also taking inspiration from nature in diagnostics. The newly developed bio-based test can replace the use of complex pumps in diagnostic procedures with simple LEDs. These so-called OptoAssays mimic the behavior of biological cells and use their genetic programming.

Lateral flow assays such as COVID-19 rapid tests work by the unidirectional movement of sample fluid across a pulp, triggered by capillary forces. However, for more complex tests that require bidirectional control of the fluid, additional mechanical pumps are required, which is costly and requires a lot of maintenance.

LEDs instead of pumps: how the OptoAssays work

The research team's OptoAssays rely on simple LEDs to enable the bidirectional transport of biomolecules and read out the test results without mechanical steps. The test consists of a transmitter and a receiver section that come into contact by adding the test reagent. A light-sensitive protein in the transmitter area reacts to illumination with red light (660 nm wavelength) and binds molecules. Dark red light (740 nm wavelength) releases the molecules from the protein again. In the receiver area, antibodies detect the protein sought in the sample. The method is inspired by the functioning of plant cells, in which photoreceptors react to light and thereby control certain cell processes.

Bio-based components: Sustainable diagnostics

The photoreceptors in the OptoAssay are obtained from plant genes and introduced into bacteria, which then produce them. As a result, natural components that can be produced sustainably replace the mechanical components of conventional systems. By dispensing with pumps, OptoAssays can be used in a simpler, cheaper and more resource-efficient way.

Potential for on-site diagnostics

The researchers see a wide range of potential applications for OptoAssays, particularly in on-site diagnostics, similar to lateral flow assays. Dr. Can Dincer from the University of Freiburg explains: “OptoAssays can easily be controlled and read using smartphones and could, in the future, make external flow control systems such as pumps and signal-reading devices unnecessary. So, they pave the way for new diagnostic tools that enable cost-effective and straightforward analyses directly on-site, even in resource-limited settings.”

MEDICA-tradefair.com; Source: INM – Leibniz Institute for New Materials

More about the INM – Leibniz Institute for New Materials at: www.leibniz-inm.de/en