The structure-activity relationship of hydrophilic carbon dots regulated by the nature of precursor ionic liquids.

The preparation of hydrophilic carbon dots (HCDs) with imidazolium dicyanamide ionic liquids (ILs) as precursor revealed a unique structure-activity relationship for the IL-HCDs. Their hydrophilicity, fluorescence nature and cytotoxicity are closely correlated to the alkyl side chain length of the imidazolium cationic moiety. (1) The hydrophilicity of the precursor ILs decreases with the alkyl chain length of their imidazolium cations (from ethyl, butyl, hexyl, octyl to decyl). On the contrary, that of the IL-HCDs increases with the alkyl chain length due to the emergence of COC, NH2 moiety. (2) The passivation effect of alkyl chain plays a dominative role in the enhancement of quantum yield (QY, from 4.6% to 48.0%) of IL-HCDs. The doping of nitrogen-containing moieties contributes marginally. (3) The increase of alkyl chain length leads to the weakening of IL-HCDs/bovine serum albumin (BSA) affinity with a decrease on the quenching constants from 12.59 × 104 to 1.779 × 104 L mol-1. (4) The cytotoxicity of IL-HCDs increases with the length of alkyl chain in the imidazolium cation, though the hydrophilicity of IL-HCDs is increased. In addition, the cytotoxicity of IL-HCDs/BSA is lower than that of IL-HCDs. The protective effect of BSA in the IL-HCDs/BSA 'protein corona' could be utilized to improve the biocompatibility of IL-HCDs.

Glutathione triggered degradation of polydopamine to facilitate controlled drug release for synergic combinational cancer treatment.

Here we report a novel mechanism for triggering drug release in the polydopamine (PDA)-coated magnetic CuCo2S4 core-shell nanostructure by glutathione (GSH) triggered degradation of PDA for release. In the design, we used PDA coated CuCo2S4 as the nanocarrier with polyethylene glycol and folic acid targeting molecules to ensure the safe delivery of doxorubicin (DOX) to cancer cells. In addition, the controlled release could be enforced by taking advantage of the pH sensitivity of PDA to tumor acidic environments. The targeting and treatment of HeLa cancer cells were very effective and the killing was more efficient at higher levels of GSH. Furthermore, the designed system not only could be used for drug delivery but also could combine photothermal therapy with chemotherapy in a synergetic way. Plus, the system could be used for magnetic resonance imaging (MRI), which is beneficial for imaging-guided treatment.