In a examine revealed in Proceedings of the Nationwide Academy of Sciences, a analysis staff led by Prof. Dongguo Zhang of the College of Science and Expertise of China (USTC) of the Chinese language Academy of Sciences (CAS) developed an optical module consisting of cascaded momentum-space polarization filters primarily based on vector mild discipline modulation.
This optical module successfully suppresses background noise whereas capturing excessive signal-to-noise ratio (SNR) microscopy photos of particular person nano-objects.
Exact imaging of the evolution and movement habits of particular person nano-objects, resembling ultrafine atmospheric particles, is essential in terms of understanding their functionalities and properties. Label-free optical microscopy has been broadly utilized in imaging and sensing of nanoparticles because of its distinctive non-destructive, non-invasive and quick detection traits.
Nonetheless, the power of sunshine scattering by particular person nanoparticles in air drops considerably with particle measurement to the sixth energy. In consequence, the scattered mild depth is considerably decrease than the background noise, making it tough for conventional label-free optical microscopes to perform excessive SNR imaging of particular person nanoparticles.
To deal with this concern, Prof. Zhang’s staff developed a momentum-space polarization filter that can be utilized to change vector discipline polarization.
Solely scattering mild from single nano-objects can go by way of the filter and be caught by the detector, whereas various background noise is considerably filtered and suppressed, subsequently attaining excessive distinction and excessive SNR imaging of nano-objects.
The filter was positioned on the exit finish of a complete inside reflection microscopy (TIRM) to indicate how it’s used. Compared to conventional label-free black-field microscopy, black-field microscopy, which has decreased (blacker) background noise and higher detection sensitivity, was achieved by changing TIRM into black-field microscopy as soon as the filter was put in.
As such, it was made clear that black-field microscopy can be utilized to acquire real-time excessive SNR and high-contrast optical microscopy photos of particular person protein molecules, gold nanoparticles, and perovskite nanocrystals.
Moreover, single perovskite nanocrystals endure anion-exchange reactions upon the sequential introduction of HCl and HI vapor. These processes alter the nanocrystals’ form and refractive index, therefore inflicting variations within the scattered mild indicators of the person nanocrystals.
Black-field microscopy can seize this course of in real-time, providing a novel photonic approach for the detection of bodily and chemical reactions happening as a nanoobject’s properties evolve.
The momentum-space polarization filter gadget is exclusive in that it may be used to supply black-field imaging functionality to standard label-free optical microscopy, together with floor plasmon resonance microscopy (SPRM), TIRM, and different near-field optical microscopy, with out altering the interior construction of the microscopes. This tremendously will increase the sensitivity of the microscopes in detecting particular person nano-objects.
In abstract, the staff created a novel platform for analyzing particular person nanoparticles utilizing black-field microscopy, which holds vital promise to be used within the fields of supplies science, biology, physics, and environmental science.
Journal Reference:
Liu, Y., et. al. (2024) Cascaded momentum-space polarization filters enabled label-free black-field microscopy for single nanoparticles evaluation. Proceedings of the Nationwide Academy of Sciences. doi:10.1073/pnas.232182512