Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
J Colloid Interface Sci. 2019 Oct 15;554:722-730. doi: 10.1016/j.jcis.2019.07.058. Epub 2019 Jul 23.
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, NH 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 × 10 to 1.779 × 10 L mol. (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.
以咪唑二氰胺离子液体（ILs）为前体制备亲水性碳点（HCDs），揭示了 IL-HCDs 的独特结构-活性关系。它们的亲水性、荧光性质和细胞毒性与咪唑阳离子部分的烷基侧链长度密切相关。（1）前体 ILs 的亲水性随其咪唑阳离子的烷基链长度（从乙基、丁基、己基、辛基到癸基）而降低。相反，由于 COC、NH 部分的出现，IL-HCDs 的亲水性随烷基链长度的增加而增加。（2）烷基链的钝化效应在 IL-HCDs 量子产率（从 4.6%到 48.0%）的提高中起主导作用。氮杂原子的掺杂作用贡献较小。（3）烷基链长度的增加导致 IL-HCDs/牛血清白蛋白（BSA）亲和力减弱，猝灭常数从 12.59×10 降至 1.779×10 L mol。（4）尽管 IL-HCDs 的亲水性增加，但 IL-HCDs 的细胞毒性随咪唑阳离子中烷基链的长度而增加。此外，IL-HCDs/BSA 的细胞毒性低于 IL-HCDs。BSA 在 IL-HCDs/BSA“蛋白质冠”中的保护作用可用于提高 IL-HCDs 的生物相容性。
