Different Color Emissive Copper Nanoclusters for Cancer Cell Imaging

Different sized copper nanoclusters (CuNCs) have been synthesized in water from the same metal precursor and stabilizing agent, only by altering the reducing agent, temperature and pH of the medium. As-synthesized clusters were thoroughly characterized by fluorescent spectroscopy, matrix-assisted laser desorption ionization (MALDI) mass spectrometry, X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM). Interestingly, the emissive color of nanoclusters has been successfully tuned from blue to orange-red in aqueous media and four different color emitting clusters have been found, namely, blue, cyan, green and orange-red. Orange-red emitting CuNC is associated with a large Stokes shift of 283 nm and it is non-cytotoxic in nature. Fluorophores with such high Stokes shift are highly advantageous for modern microscopic techniques; in this study, the as-synthesized orange-red emitting clusters have been employed for imaging of cancer cells to check their ability for cell imaging for future biomedical applications.