'Light tweezers' used to trap and move viruses

An international team of scientists, led by Nanyang Technological University, Singapore (NTU Singapore), has created a laser-powered device that can trap and move viruses using nothing but light.

The device has the ability to manipulate light to act as ‘tweezers’, and can precisely ‘move’ a single virus to target a particular part of a cell. It could therefore aid in enabling new approaches to disease diagnosis and the study of viruses, as well as vaccine development, according to a study published in the journal ACS Sensors.

As explained by NTU Associate Professor Eric Yap, who co-led the research, “The conventional method of analysing viruses today is to study a population of thousands or millions of viruses. We only know their average behaviour as an entire population. With our laser-based technology, single viruses could be studied individually.”

Measuring 2 x 2 cm (about the size of a thumbnail), the device consists of a chip that is made from a wafer of silicon oxide and silicon nitride, with nanometre-sized cavities to contain the trapped viruses. Above the chip is a laser directing highly focused light beams with the right amount of energy to act as a pair of ‘tweezers’ that can isolate and move viruses.

The device works by loading a fluid that contains viruses, such as blood, into the chip, after which point a laser beam is directed onto it, forming spots of light. As the intensity of the light is highest in the centre of the spots, this creates a strong force that attracts and traps the virus in designated cavities on the chip. By shifting the locations of the spots of light, viruses can be freely moved to other parts of the chip. This allows for the easy sorting and concentrating of viruses of different sizes, ranging from 40 to 300 nm.

“Our invention is a breakthrough in virus research as it allows us to single out individual specimens for study,” said research leader Professor Liu Aiqun.

“For example, we can isolate individual viruses with mutations to develop therapies against these variants. Our invention uses insulating materials that are biocompatible and do not heat up easily, unlike current sorting methods that generate a lot of heat. This means scientists should be confident in handling viruses with this device without affecting their properties and viability.”

“As well as diagnosing diseases, our device could be used to spot the outliers — the rare individual virus that has the potential to evolve and create the next wave of an epidemic, for instance,” Assoc Prof Yap added. “This brings us into an era where we can contemplate precision diagnostics at the single virus level.”

The researchers tested their device, known as a digital virus manipulation chip, on adenoviruses — a group of common viruses that can cause cold-like symptoms and measure 90 to 100 nm in diameter. Prof Liu believes it could also be used to trap and concentrate the SARS-CoV-2 virus for research and diagnosis, as it is similar in size (80 to 120 nm in diameter).

The scientists are currently working on expanding the usage of their laser-powered device. For example, they are looking to study how the device can direct the isolated viruses to infect a targeted part of a human cell. The team said this would lead towards advances in virus research and improve the efficiency of vaccine and antiviral drug development.

Image courtesy of the study authors.

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