DA ZP1 (diacetylated Zinpyr1), a highly sensitive fluorogenic Zn(II) sensor (KdZn2+= 0.6 nM), efficiently images and isolates pancreatic β-cells and β-like cells in vitro and purifies live stem cell-derived β-like cells. It also enables imaging of transplanted islet grafts and endogenous mouse islets in vivo. DA ZP1 is initially non-fluorescent; however, its interaction with Zn(II) ions triggers hydrolytic cleavage of the acetyl groups, creating a robust fluorescent signal with excitation and emission maxima (λ) at 490 nm and 522 nm, respectively.