Metal nanoprobe-decorated all-inorganic perovskite nanocrystal-based fluorescence-linked immunosorbent assay for the detection of tumor-derived exosomes.

All-inorganic perovskite nanocrystals (CsPbX 3 NCs, X = Cl, Br, I) are promising fluorescence materials for biological detection due to their excellent optical properties. However, there is still a challenge to obtain stable CsPbX 3 NCs with more biofunctions. Here, we proposed a distinct strategy by absorbing the functionalized metal nanoprobes onto the phospholipid encapsulated CsPbX 3 NCs to achieve CsPbX 3 -metal hybrids as probes for the detection of tumor-derived exosomes. Here, the metal nanoprobes have two functions: first, it endows phospholipid encapsulated CsPbX 3 NCs with recognition ability; second, it avoids the fluorescence quenching of CsPbX 3 NCs during the biological modification process by using metal nanoparticles as a bridge to connect with CsPbX 3 NCs and various biomolecules. The obtained CPXD-AD exhibited a bright fluorescence signal, narrow full width at half-maximum (FWHM), and high specificity. Under optimal conditions, the CPXD-AD-based fluorescence-linked immunosorbent assay (FLISA) was successfully established and used for both qualitative and quantitative detection of tumor-derived exosomes.