Structure Tailoring\nof Hemicyanine Dyes for <i>In Vivo</i> Shortwave Infrared\nImaging

<i>In vivo</i> bioimaging\nusing shortwave infrared (SWIR)\n(1000–2000 nm) molecular dyes enables deeper penetration and\nhigher contrast compared to visible and near-infrared-I (NIR-I, 700–900\nnm) dyes. Developing new SWIR molecules is still quite challenging.\nThis study developed <b>SRHCYs</b>, a panel of fluorescent dyes\nbased on hemicyanine, with adjustable absorbance (830–1144\nnm) and emission (886–1217 nm) wavelength. The photophysical\nattributes of these dyes are precisely tailored by strengthening the\ndonor parts and extending polymethine chains. <b>SRHCY-3</b>, with its clickable azido group, was chosen for high-performance\nimaging of blood vessels in living mice, enabling the precise detection\nof brain and lung cancer. The combination of these probes achieved <i>in vivo</i> multicolor imaging with negligible optical crosstalk.\nThis report presents a series of SWIR hemicyanine dyes with promising\nspectroscopic properties for high-contrast bioimaging and multiplexing\ndetection.