April 20, 2024

Researchers at the UTS Institute for Biomedical Materials and Devices have significantly advanced optical tweezer tech, which will boost biomedical research.

Scientists can use light, or ‘optical force,’ to move small particles like Star Wars’ Jedis use ‘the Force’ to control distant objects. This groundbreaking laser technology, optical tweezers, was awarded the 2018 Nobel Prize for Physics.

Optical tweezers can be used in medicine, biology, and materials science to build and manipulate nanoparticles, such as gold atoms. The technology depends on a difference between the environment and the trapped particle’s refractive properties.

Scientists have discovered a new method to manipulate particles with the same refractive properties as the background environment. This overcomes a fundamental technical problem.

The article: ‘Optical tweezers beyond the refractive index mismatch using highly-doped upconversion nanoparticles’ was published in Nature Nanotechnology.

“This breakthrough has enormous potential, especially in fields like medicine,” Dr. Fan Wang, University of Technology Sydney (UTS).

“The ability to measure, push, and measure the forces of microscopic cells, such as DNA strands or intracellular enzymes, could make it possible to understand and treat many diseases, including cancer and diabetes.

“Traditional mechanical microprobes are used to manipulate cells but can be invasive and have a low positioning resolution. He says they can only measure the stiffness of the cell membrane and not the force of molecular motor protein inside the cell.

The research team developed a unique technique to control nanoparticles’ luminescence and refractive properties. This was achieved by doping nanocrystals containing rare-earth metal ions.

After overcoming this fundamental problem, the team optimized the doping concentration of ions to trap nanoparticles at lower energy levels and with a greater efficiency of 300%.

To trap a 20-nanometer gold particle, you would need hundreds of milliwatts (or more) of laser power. Using our new technology, we can trap a particle of 20-nanometer size using tens of millions of watts of power,” says Xuchen Shan (first co-author and Ph.D. student at the UTS School of Electrical and Data Engineering).

“Our optical tweezers also reached a record-breaking level of sensitivity, or stiffness, for nanoparticles in water solutions.” He says that the heat generated by this method was negligible compared to older methods. “Our optical tweezers offer many advantages.”

Peter Reece from the University of New South Wales is a co-author and says that this proof-of-concept research is an essential advancement in a field that’s becoming more sophisticated for biological researchers.

The prospect of creating a high-efficiency nanoscale force probe is exciting. He hopes that the force probe will be able to be labeled to target intracellular organelles and structures, enabling optical manipulation of these structures.”

According to Distinguished Professor Dayong Jin (Director of the UTS Institute for Biomedical Materials and Devices) and co-author, this work opens up new possibilities for super-resolution functional imaging intracellular biomechanics.

Professor Jin says the IBMD research focuses on translating photonics and material technology advances into biomedical uses. This type of technology development aligns well with this vision.

“Once we have answered fundamental science questions and found new mechanisms of photonics and material science, we can apply them.” This breakthrough will enable us to use less-invasive and lower-power methods to trap nanoscopic objects such as living cells and intracellular compartments for precise manipulation and measurement of nanoscale biomechanics.

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