Biomedical applications of full-spectrum photoacoustic imaging for wavelength-dependent endogenous molecules

Photoacoustic imaging has emerged as a promising technology in the life sciences, exploiting the relatively weak scattering of sound in biological tissues to overcome the penetration limits inherent in conventional optical imaging. Relying on the photoacoustic effect, this imaging modality enables the identification of a wide range of endogenous molecules by analyzing their unique optical absorption spectra. This review summarizes characteristic molecules commonly employed in photoacoustic imaging and their corresponding biomedical applications across the full spectrum, including key bands such as X-ray, ultraviolet, visible, near-infrared, mid-infrared, terahertz, and microwave. Furthermore, the paper also outlines the main endogenous molecules used in photoacoustic imaging and their successful clinical applications, identifies current challenges in the development of full-spectrum photoacoustic imaging, and offers perspectives on future directions for technological advancement. Continued progress in photoacoustic imaging is expected to broaden its advantages, thereby facilitating advancements in biomedicine.