Fig. 1: Intravital co-localized imaging of mLVs and CVs.

Two wavelengths are focused on the same depth position and scanned alternately to capture images of mLVs and CVs. Exogenous contrast nanoprobes, created by loading ICG dye on OVA, are utilized to enhance the visualization of mLVs. CVs are imaged using a visible laser, relying on endogenous contrast from hemoglobin. The photoacoustic signals generated by the exogenous tracer and the endogenous hemoglobin are first coupled through a water tank filled with deionized water and then detected by the ultrasound transducer. M mirror, DM dichroic mirror, L lens; Obj, objective lens; UT, ultrasound transducer