A research team at City University of Hong Kong has developed a multispectral, ultra-low dose photoacoustic microscope system

Optical resolution "photoacoustic microscope is a new biomedical imaging technology, which can be used in the research of cancer, diabetes, stroke and other diseases. However, insufficient sensitivity has always been a long-term obstacle to its wider application.

According to Maims Consulting, a research team from City University of Hong Kong (CityU) has recently developed a multispectral, ultra-low dose photoacoustic microscope (SLD-PAM) system, which has significantly improved its sensitivity limit, providing the possibility for future new biomedical applications and clinical conversion, The relevant research results are published in the Advanced Science journal under the title of "Super Low Dose Functional and Molecular Photoacoustic Microscope".

Photoacoustic microscopy combines ultrasonic detection and laser induced photoacoustic signals to create detailed images of biological tissues. When biological tissue is irradiated by pulsed laser, ultrasound is generated, which is then detected and converted into electrical signals for imaging. Compared with traditional optical microscopy methods, this novel technique can achieve capillary level or subcellular level resolution at a greater depth. However, insufficient sensitivity hinders the wider application of this technology.

High sensitivity is important for high-quality imaging. It helps detect chromophores that do not strongly absorb light (molecules that give material color by absorbing visible light at specific wavelengths). It also helps to reduce photobleaching and phototoxicity, reduce interference with fragile organ biological tissues, and provide more optional low-cost, low-power lasers over a wide spectral range Professor Wang Lidai from the Department of Biomedical Engineering at City University of Hong Kong explained.

For example, in ophthalmic examinations, low-power lasers are preferred for greater safety and comfort. He added that long-term monitoring of pharmacokinetics or blood flow requires low-dose imaging to reduce interference with tissue function.

In order to overcome the sensitivity challenge, Professor Wang Lidai and his research team recently developed a multispectral, ultra-low dose photoacoustic microscope system, breaking the sensitivity limit of traditional photoacoustic microscopes and significantly increasing the sensitivity by about 33 times.

They achieved this breakthrough through improvements in the design of photoacoustic sensors, combined with the 4D spectral spatial filter algorithm used for computation. Researchers have improved the design of photoacoustic sensors by using laboratory customized high numerical aperture acoustic lenses, optimizing optical and acoustic beam combiners, and improving optical and acoustic alignment. The photoacoustic microscope system also utilizes low-cost multi wavelength pulse lasers to provide 11 wavelengths from green to red light. Its laser operates at a repetition rate of up to megahertz, with a spectral switching time of sub microseconds.

In order to demonstrate the importance and novelty of the photoacoustic microscope system, the research team conducted comprehensive systematic testing on it through ultra-low pulse in vivo animal imaging using green and red light sources, and achieved significant results.

Firstly, the photoacoustic microscope system can achieve high-quality in vivo anatomy and functional imaging. The ultra-low laser power and high sensitivity significantly reduce interference in eye and brain imaging, paving the way for clinical conversion. Secondly, without affecting image quality, the lower laser power of this photoacoustic microscope system reduces photobleaching by about 85% and enables the use of a wider range of molecules and nanoprobes. In addition, the system significantly reduces costs, making research laboratories and clinics more affordable.

Professor Wang Lidai said, "This photoacoustic microscope system can perform non-invasive imaging of biological tissues with minimal damage to subjects, providing a powerful and promising tool for anatomical, functional, and molecular imaging. We believe that this photoacoustic microscope system will help advance the application of photoacoustic imaging, achieve many new biomedical applications, and pave the way for clinical transformation.

Next, Professor Wang Lidai and his research team will use the system to test a wider range of small molecule and gene encoded biomarkers in biological imaging. They also plan to experiment with more types of low-power light sources in a wide spectrum to develop wearable or portable photoacoustic imaging microscopes.

Source: Sohu