A biocompatible poly(N-vinylimidazole)-dot with both strong luminescence and good catalytic activity†
Abstract
Poly(N-vinylimidazole) (PVIm) that contains a large amount of bio-active imidazole units was used as the sole carbon source to synthesize PVIm-dot through a one-pot hydrothermal method without any further modification and surface passivation. The measurements of X-ray photoelectron spectroscopy, dynamic light scattering, transmission electron microscopy and X-ray diffraction proved that only a slight carbonization occurred during the hydrothermal treatment of PVIm. The characterizations of 1H NMR, FTIR and thermogravimetric analysis verified that the obtained PVIm-dot well inherited the chemical structure of its precursor PVIm. Unlike PVIm, the obtained PVIm-dot showed an obvious excitation-dependent photoluminescence (PL) behavior, and its PL features were quite stable at different pH values and ionic strength. The PVIm-dot possessed low cytotoxicity and could enter cancer cells, making it a suitable candidate for bio-imaging. Moreover, the PVIm-dot still kept the catalytic activity of its imidazole units. With the catalytic hydrolysis of p-nitrophenyl acetate as the model reaction, it was found that the PVIm-dot showed good catalytic activity in this reaction and its catalytic efficiency was better than PVIm. What's more, the variation of PL intensity during the reaction could be used as a luminescent sensor to monitor the progress of the hydrolysis reaction.