Dr. Changhui Li and his research team’s paper, “Label-free imaging of zebrafish larvae in vivo by photoacoustic microscopy,” was chosen among February’s “Top 10 Downloads in Biomedical Optics Express.”

Li is an associate professor in the Department of Biomedical Engineering at the College of Engineering. 

Zebrafish is one of the most important animal models for developmental study and disease research. Traditional microscopic imaging methods generally require the fluorescence labeling to achieve high-contrast images. Based on zebrafish tissue's intrinsic optical absorption property, Li’s lab accomplished the label-free in-vivo high resolution imaging of whole body circumlocutory system of zebrafish larva. This method can be implemented in research of other animal models, providing a powerful new imaging method for life science and preclinical medicine research.

The following figure shows the photoacoustic microscopy (PAM) system developed in Li's lab. This system obtains high resolution by optical focus and high contrast by detecting the ultrasonic waves through photoacoustic effect.

Fig.1 Imaging system

Figure 2 demonstrates the in-vivo imaging result. Because the hemoglobin molecules in zebrafish's circumlocutory system highly absorb the 532nm laser used in the experiment, blood vessels present a strong photoacoustic effect. Figure 2(a) is the result of PAM imaging. Compared with other optical imaging methods, PAM provides the label-free whole body imaging with high resolution.

Fig. 2 Imaging results. (a) By photoacoustic microscopy; (b) By optical microscopy; (c) By optical coherence tomography.

The article is a collaborative work with Professor Jingwei Xiong’s lab in the Institute of Molecular Medicine of Peking University. It is  funded by National Science Foundation of China and National Basic Research Program of China (973 Program).