Department of Biophysics, Warsaw University of Life Sciences (SGGW) , 159 Nowoursynowska Street, 02776 Warsaw, Poland.
J Phys Chem B. 2017 Jul 20;121(28):6822-6830. doi: 10.1021/acs.jpcb.7b04295. Epub 2017 Jul 5.
The interactions of fluorescent probes and biomolecules with nanocarriers are of key importance to the emerging targeted drug delivery systems. Graphene oxide nanosheets (GONs) as the nanocarriers offer biocompatibility and robust drug binding capacity. The interactions of GONs with fluorophores lead to strong fluorescence quenching, which may interfere with fluorescence bioimaging and biodetection. Herein, we report on the interactions and energy transfers in a model ternary system: GONs-FITC-ATP, where FITC is a model fluorophore (fluorescein isothiocyanate) and ATP is a common biomolecule (adenosine-5'-triphosphate). We have found that FITC fluorescence is considerably quenched by ATP (the quenching constant K = 113 ± 22 M). The temperature coefficient of K is positive (α = 4.15 Mdeg). The detailed analysis of a model for internal self-quenching of FITC indicates that the temperature dependence of the net quenching efficiency η for the FITC-ATP pair is dominated by FITC internal self-quenching modes with their contribution estimated at 79%. The quenching of FITC by GONs is much stronger (K = 598 ± 29 M) than that of FITC-ATP and is associated with the formation of supramolecular assemblies bound with hydrogen bonding and π-π stacking interactions. For the analysis of the complex behavior of the ternary system GONs-FITC-ATP, a model of chemisorption of ATP on GONs, with partial blocking of FITC quenching, has been developed. Our results indicate that ATP acts as a moderator for FITC quenching by GONs. The interactions between ATP, FITC, and GONs have been corroborated using molecular dynamics and quantum mechanical calculations.
纳米载体上荧光探针和生物分子的相互作用对于新兴的靶向药物传递系统至关重要。氧化石墨烯纳米片（GONs）作为纳米载体具有生物相容性和强大的药物结合能力。GONs 与荧光团的相互作用导致强荧光猝灭，这可能会干扰荧光生物成像和生物检测。在此，我们报告了模型三元体系中相互作用和能量转移的情况：GONs-FITC-ATP，其中 FITC 是模型荧光团（异硫氰酸荧光素），ATP 是常见的生物分子（腺苷-5'-三磷酸）。我们发现 FITC 荧光被 ATP 显著猝灭（猝灭常数 K = 113 ± 22 M）。K 的温度系数为正（α = 4.15 Mdeg）。对 FITC 内部自猝灭模型的详细分析表明，FITC-ATP 对的净猝灭效率 η 的温度依赖性主要由 FITC 内部自猝灭模式主导，其贡献估计为 79%。FITC 与 GONs 的猝灭比与 FITC-ATP 的猝灭要强得多（K = 598 ± 29 M），这与形成超分子组装有关，这些组装通过氢键和 π-π 堆积相互作用结合。为了分析三元体系 GONs-FITC-ATP 的复杂行为，开发了一个模型，即 ATP 在 GONs 上的化学吸附，部分阻断了 FITC 的猝灭。我们的结果表明，ATP 充当了 GONs 猝灭 FITC 的调节剂。使用分子动力学和量子力学计算对 ATP、FITC 和 GONs 之间的相互作用进行了验证。
