Melanoma, developing from melanocytes, is the deadliest type of malignant skin tumors in the world. Due to high lightabsorption of melanin, rare circulating melanoma cells, as an endogenous marker for metastasis at the early stage, can bequantitatively detected in small superficial vessels of mouse ears by in vivo photoacoustic flow cytometry (PAFC). Beforeclinical application, the capability of promising PAFC platform should be verified and optimized by mouse vessels, whichare similar in size and depth to human vessels. In the current study, compared with optical resolution PAFC (OR-PAFC),we build acoustic resolution PAFC (AR-PAFC) using focused ultrasonic transducer and 1064 nm laser with lower pulserate, leading to higher detection depth and lower laser power density in mouse models. Besides, based on laser frequencydoubling and high absorption coefficient of hemoglobin at 532nm wavelength, the blood vessels can be positioned by lowcostnavigation system rather than the expensive system of two coupled lasers or charged coupled device with depthlimitation. We confirm that AR-PAFC can be applied to noninvasive label-free counting of circulating melanoma cells inmouse tail veins, and validated by in vitro assays using phantom models, which simulates the scattering and absorptioncoefficients of living tissue. These results show that AR-PAFC platform has great potential for preoperative diagnosis andpostoperative evaluation of melanoma patients.
展开▼
