通过构建碳点(CDs, 供体)和曙红B(EB, 受体)间的荧光共振能量转移(FRET)体系, 建立了一种灵敏且具有选择性的检测培氟沙星(PEFL)含量的新方法。 以紫叶草为碳源, 采用热解法制备了荧光碳点(CDs), 其在水中分散性较好、 稳定性较高、 量子产率为3.7%。 利用高分辨电子显微镜(HRTEM)、 X射线电子衍射仪(XRD)和傅里叶变换红外光谱仪(FTIR)等手段对碳点进行了形貌和结构表征, 结果表明, 所制得的碳点为无定形态, 其表面含有羟基(—OH)和羧基(—COOH)等活性基团。 利用能量转移Frster理论, 确定CDs和EB之间发生了荧光共振能量转移, 从而在CDs和EB之间构建了荧光共振能量转移体系。 并考察了影响荧光共振能量转移效应测定培氟沙星的重要因素, 如反应介质和酸度、 反应时间、 供体和受体的浓度和盐效应等。 结果表明, 在pH 3.0的磷酸盐(PBS)缓冲溶液中, 以340 nm为激发波长, 碳点将能量转移给曙红B, 使得曙红B的荧光信号增强。 加入培氟沙星之后, 由于培氟沙星与碳点之间相互作用, 从而使得碳点的荧光显著增强。 并且在优化的实验条件下, 培氟沙星的浓度在0.0168~6.71 μg·mL-1范围内与体系的荧光强度改变值(ΔF)之间有较好的线性关系, 检出限为0.072 5 ng·mL-1(3s/k, n=11)。 一些常见的阳离子(如Fe3+, Al3+, Ca2+, Zn2+, Cr3+, Co2+, Cu2+, Mn2+等)、 阴离子(如Cl-, NO-3, I-, S2-, SCN-, SO2-4, Br-, NO-2, IO-3, F-, ClO-3, SO2-3等)和药物(异烟肼, 抗坏血酸和肝素钠)及三聚氰胺均不影响培氟沙星含量的测定。 将该方法用于甲磺酸培氟沙星胶囊和片剂中PEFL含量的测定, 回收率为100.4%~105.1%, 相对标准偏差(RSD, n=5)均不大于2.5%, 表明该方法可用于甲磺酸培氟沙星药物中培氟沙星的实际检测。 该方法具有灵敏度高、 选择性好等优点。

A fluorescence resonance energy transfer (FRET) system between fluorescence carbon dots (CDs, donor) and Eosin B (EB, acceptor) was constructed, and a new method for sensitive and selective determination of pefloxacin (PEFL) was proposed. Fluorescent carbon dots (CDs) were synthesized by pyrolysis treatment using Setcreasea purpurea boom as carbon source. The carbon dots exhibited preferable dispersibility in water, high stability and a quantum yield of 3.7%. The as-prepared CDs were characterized using high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction patterns (XRD), and Fourier transform infrared spectroscopy (FTIR). Theresults showed that the CDs demonstrated an amorphous structure with the presence of —OH and —COOH groups on their surface. Using Frster’s theory of resonance energy transfer, the FRET between CDs and EB was determined, and the FRET system was constructed between CDs and EB. Some important factors were optimized, such as reaction medium and acidity, reaction time, the concentration of donor and acceptor, salt effect. According to the result, in PBS buffer solution at pH=3.0, the energy transfer from CDs to EB occurred with λex=340 nm, which resulted in an enhancement of the fluorescence intensity of EB. Upon the addition of pefloxacin, the fluorescence intensity of CDs was significantly increased because of the interaction between pefloxacin and CDs. Under the optimized experimental conditions, the change of CDs fluorescence intensity (ΔF) with the PEFL concentration exhibited a linear relationship in range of 0.016 8~6.71 μg·mL-1. The detection limit was 0.072 5 ng·mL-1 based on the formula 3s/k (n=11). Most of common substances such as cations (Fe3+, Al3+, Ca2+, Zn2+, Cr3+, Co2+, Cu2+, Mn2+, etc. ), anions Cl-, NO-3, I-, S2-, SCN-, SO2-4, Br-, NO-2, IO-3, F-, ClO-3, SO2-3, etc.), medicines (isoniazide, ascorbic acid and heparin sodium) and melamine did not interfere with the detection PEFL. The proposed method was applied to determine PEFL in drugs. The recoveries were 100.4%~105.1%, and the relative standard deviations (RSD, n=5) were not more than 2.5%. This method has the advantages such as high sensitivity and good selectivity.