Moreover, a C-dot-based inorganic-organic nanosystem for two-photon imaging and biosensing of pH variation in living cells and tissues has also been designed by Kong’s research see more group . Almost during the same period, C-dots with PEI (polyetherimid)-passivation were used for bioimaging and as nanocarrier for gene delivery . However,
with the rapid progress of research and application, many defects were thoroughly exposed such as low photoluminescence intensity, short wavelength excitation, and difficulties in separation and purification, which did hinder it to further in vitro or in vivo biological applications. Previously, preparation of surfaced-functionalized C-dots usually included three steps: synthesis of raw C-dots, passivation operations, and functionalization reactions . Most C-dots prepared, if without further complicated purification, passivation, and functionality, featured quite low quantum yield (around or less than 5%) [1, 17–22] and retained very limited application potentials. So it is extremely necessary to find a simply strategy to fabricate surface-functionalized C-dots with relatively high quantum efficiency. As to the preparation methods, they could Tipifarnib molecular weight be divided into two categories: top-down methods and bottom-up methods. The bottom-up methods usually suffer from complex processes, or expensive
starting materials and PLX4032 datasheet severe synthetic conditions, which are unlikely to be extended significantly in the near future . Alternatively, bottom-up synthetic approaches
based on chemistry have been desired to achieve C-dots with fluorescence. Presently, Li et al. reported a facile hydrothermal method to prepare luminescent carbon dots (L-CDs) with high Phosphoprotein phosphatase quantum yield value (44.7%) and controllable emission wavelengths and used prepared carbon dots to detect toxic Be2+ ions . To date, microwave pyrolysis approach, as one family member of bottom-up synthesis methods, has been developed and widely used for its simplicity, cost/time-efficiency, environmental friendliness, easiness to scale up, and more importantly convenience to realize synthesis, passivation, and functionalization reactions simultaneously through only one synthesis step [4, 24]. Herein, we report for the first time a green synthesis route, only one synthesis step followed by limited and simple purification, without further passivation and surface functionality to prepare ribonuclease A-conjugated C-dot nanoclusters (RNase [email protected]). It is well known that RNase A is a low molecular weight protein (approximately 124 residues, approximately 13.7 kDa, pI = 9.4) with a globular conformation (2.2 nm × 2.8 nm × 3.2 nm) . The protein has proved to be thermally stable , even under microwave heating for a couple of minutes .