Abstract：Photoacoustic imaging (PAI) overcomes the optical diffusion limit and provides deeper tissue imaging with high spatial resolution by integrating high selectivity of optical imaging with deep penetrating of ultrasonic imaging. Various endogenous chromophores such as oxygenated hemoglobin, deoxygenated hemoglobin, melanin, and lipid can serve as PAI contrast agents, enabling brain function study, tumor microcirculation visualization, and atherosclerotic plaque identification. PAI has shown great application prospect in biomedicine. However, in most cases, intrinsic biomarkers of many diseases cannot generate PA signals by themselves after laser excitation. Using exogenous PA probes to stain PAIinvisible biomarkers is effective at fully utilizing PAI’s potential at a depth and spatial resolution. The combination of the functional probes and PAI: photoacoustic molecular imaging, will expand the application range of PAI, ultimately accurately detects intrinsic biomarkers of these diseases in living subjects. Photoacoustic molecular imaging will provide strong technical support for the early diagnosis of target disease. In this work, we develop gold nanobipyramids with narrow plasmon linewidths as a novel photoacoustic probe. The absorption peak of the gold nanobipyramids can be adjusted arbitrarily by selecting different ratio of length and diameter. By tuning the wavelength of the excitation laser, photoacouatic signal of gold nanobipyramids with different absorption peaks can be excited selectively. The gold nanobipyramids with narrow plasmon linewidths is likely for the be used for multispectral photoacoustic imaging for the detection of different targets.
