2.6. In vivo NIR-II & visible fluorescence imaging system

The in vivo NIR-II & visible fluorescence imaging system consisted of an NIR-II fluorescence imaging system which was described in our previous study [26] and an ultraviolet lamp. The beam of 808 ​nm laser was coupled to a collimator and expanded by a lens, providing uniform irradiation on the imaging flied. Initially, a fixed focal lens was used to collect the signals and an InGaAs camera (SW640, Tekwin, Xi'’an, China) was utilized to detect the NIR-II fluorescence signals through a 1100 ​nm long-pass filter or 1400 ​nm long-pass filter (Thorlabs, USA). Later, the ultraviolet lamp was manipulated as the light source, and the visible fluorescence could be witnessed with the naked eye or a CCD camera.