High-resolution, high-contrast mid-infrared imaging of fresh biological samples with ultraviolet-localized photoacoustic microscopy
Junhui Shi, Terrence Wong, Yun He, Lei Li, Ruiying Zhang, Christopher Yung, Jeeseong C. Hwang, Lihong Wang
Mid-infrared (MIR) microscopy provides rich chemical and structural information about biological samples, without staining. Conventionally, the long MIR wavelength severely limits the lateral resolution owing to optical diffraction; moreover, the strong MIR absorption of water ubiquitous in fresh biological samples results in high background and low contrast. To overcome these limitations, we propose a method that employs photoacoustic detection highly localized with a pulsed ultraviolet (UV) laser on the basis of the Grüneisen relaxation effect. For cultured cells, our method achieves water-background free MIR imaging of lipids and proteins at UV resolution, at least an order of magnitude finer than the MIR diffraction limits. Label-free histology using this method is also demonstrated in thick brain slices. Our approach provides convenient high-resolution and high-contrast MIR imaging, which can benefit diagnosis of fresh biological samples.
, Wong, T.
, He, Y.
, Li, L.
, Zhang, R.
, Yung, C.
, Hwang, J.
and Wang, L.
High-resolution, high-contrast mid-infrared imaging of fresh biological samples with ultraviolet-localized photoacoustic microscopy, Nature Photonics
(Accessed October 4, 2023)