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A deep understanding of the molecular interactions of carbon nanodots with biomacromolecules is essential for wider applications of carbon nanodots both in vitro and in vivo. Herein, nitrogen and sulfur co-doped carbon dots (N,S-CDs) with a quantum yield of 16% were synthesized by a 1-step hydrothermal method. The N,S-CDs exhibited a good dispersion, with a graphite-like structure, along with the fluorescence lifetime of approximately 7.50 ns. Findings showed that the fluorescence of the N,S-CDs was effectively quenched by bovine hemoglobin as a result of the static fluorescence quenching. The mentioned quenching mechanism was investigated by the Stern-Volmer equation, temperature-dependent quenching, and fluorescence lifetime measurements. The binding constants, number of binding sites, and the binding average distance between the energy donor N,S-CDs and acceptor bovine hemoglobin were calculated as well. These findings will provide for valuable insights on the future bioapplications of N,S-CDs.

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Semi-interpenetrating polymer networks (semi-IPNs) composed of poly(dimethyl-aminoethyl methacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) were synthesized by ␥-radiation; three semi-IPNs with 80 : 20, 90 : 10, and 95 : 5 weight ratios of DMAEMA/PEO were obtained by use of this technique. The gel-dose curves showed that the hydrogels were characterized by a structure typical of semi-IPNs and the results of elemental analysis supported this point. The temperature-induced phase transition of semi-IPNs with the composition of 95 : 5 was still retained, with the lower critical solution temperature of PDMAEMA shifting from 40 to 27°C. The temperature sensitivity of the other two semi-IPNs gradually disappeared. The pH sensitivity of three semi-IPNs was still retained but the pH shifted slightly to lower values with increasing PEO content in the semi-IPNs. The effect of PEO content in semiIPNs on their environmental responsiveness was discussed.