Developing luminogens to advance multi-photon theranostics

Multi-photon theranostics uses luminogens, small fluorescent molecules, to enable medical imaging and therapy under the irradiation of a femtosecond laser. The technique can probe deep into biological samples and has higher spatial resolution than CT scans, MRI, and micro-ultrasonography.

In recent years, multi-photon theranostics has been used in the lab for brain vasculature imaging and truncation, tumor targeting, and tumor photodynamic therapy. In the future, the high resolution will allow for the study of in vivo biological activities like hemodynamics and neuron activities.

Luminogens can be endowed with multi-photon properties and have been injected into small animals, making them a potential component for theranostics in humans. Fan et al. summarized recent advances in developing luminogens with aggregation-induced emission characteristics, referred to as AIEgens.

“The fluorescence of conventional luminogens is easily quenched in the aggregation state,” said author Zhourui Xu. “However, AIEgens do not have such a problem. The fluorescence of AIEgens becomes stronger with the aggregation process.”

The team summarized design strategies for AIEgens, guidelines to support their development, and recent advances in the field. They also described physical and chemical properties and capabilities of AIEgens alongside molecular design and preparation of AIE nanoparticles.

The scientists discussed future applications for multi-photon theranostics, but also emphasized potential challenges. More research needs to be done to clarify the biodistribution and exposure risk of AIEgens before they are used in clinical trials.

“We hope to encourage further exploitation of AIEgens to advance multi-photon theranostics,” said Xu.

Source: “Recent advances of luminogens with aggregation-induced emission in multi-photon theranostics,” by Miaozhuang Fan, Zhourui Xu, Maixian Liu, Yihang Jiang, Xiaomin Zheng, Chengbin Yang, Wing-Cheung Law, Ming Ying, Xiaomei Wang, Yonghong Shao, Mark T. Swihart, Gaixia Xu, Ken-Tye Yong, and Ben Zhong Tang, Applied Physics Reviews (2021). The article can be accessed at https://doi.org/10.1063/5.0071142 .