Nucleobase chemosensor based on carbon nanodots

A facile and sensitive fluorescence protocol for nucleobase detection was developed based on carbon nanodot (CD) chemosensors. The novel fluorescent CDs were prepared using four kinds of nucleobases (including adenine, guanine, thymine and cytosine) as separate carbon sources-via simple hydrothermal strategy. The quantum yield of adenine CDs (A-CDs), guanine CDs (G-CDs), thymine CDs (T-CDs) and cytosine CDs (C-CDs) was checked as 15.1%, 28.3%, 10.6% and 11.7%, respectively. Four CDs can recognize their complementary nucleobases based on the principle of complementary base pairing. Their fluorescence was linearly quenched with the increase of nucleobase concentrations under optimal conditions. Combining the calibration curve, quantitative assay of nucleobase in solution can be realized. For example, A-CDs could determine thymine in the concentration range of 2-20 mM with a detection limit of ca. 0.053 mM, and the linear equation is fitting as (I-0-I) / I = 0.01961 x C tau(mM) + 0.01756 (R-2 = 0.994). Thymine can induce the fluorescence lifetime of A-CDs decreasing from 5.58 to 3.34 ns, indicating a dynamic quenching mechanism. The novel nucleobase sensors were also evaluated in specific solution environment. A-CDs showed a relatively minor relative standard deviation ( < 4.0%) in fetal calf serum solution, indicating a high accuracy and credibility of the sensing system. In view of the excellent sensitivity, preferable biocompatibility as well as simple constructing method,"the sensing platform derived from the nucleobase-based CDs present great potential in biological sensing applications.