Phospholipid-stabilized CuxAg1−xInSe2 nanocrystals as luminophores: fabrication, optical properties, and biological application†
Ternary I–III–VI semiconductor-based nanocrystals (NCs) exhibit a wide range of applications in optoelectronics, photovoltaics, and biolabeling. This motivates the in-depth study of a method to synthesize them and explore their optical properties. We present an approach for the synthesis of quaternary CuxAg1−xInSe2 (x = 0–1) NCs by means of the cation exchange reaction starting from AgInSe2 NCs. By tailoring the thermodynamic and kinetic parameters, control over both the composition and bandgap was successfully achieved. The optical properties demonstrated significant nonlinear behavior, whereby the photoluminescence (PL) wavelength and bandgap evolved steeply for a range of x < 0.5 but became invariant when x > 0.5. Optical characterizations indicated that two distinct transition processes, i.e., donor–acceptor pair and free-to-bound recombinations dominated the PL emissions for CuxAg1−xInSe2 NCs with different x values. Furthermore, the obtained NCs were directly modified with phospholipids. In vitro experiments illustrated that the phospholipid-decorated CuxAg1−xInSe2 NCs have excellent biocompatibility and can be used as a fluorescent marker for the fast bioimaging of cancer cells and cancer stem cells in the visible and NIR regions.