Ciprofloxacin (CIP) is one of the common drug pollutants whose residues are often detected in the environment. In the current work, CIP was studied in aqueous environment based on a natural fluorescing compound called phycocyanin (PC). Using, a Spectro fluorophotometer, fluorescence detection of CIP was performed, and absorbance properties were studied using a UV–Visible spectrophotometer. In addition, a circular dichroism (CD) spectrophotometer and molecular docking analysis were implemented for further investigation. As the fluorometric measurement results showed, the fluorescence intensity of PC dropped linearly upon the addition of increasing amounts of CIP ranging from 0 to 120 μmol/L of final concentrations, with the limit of detection reaching down to 95 nM. In addition, the fluorescent sensor was found to be more selective towards CIP when tested against other six antibiotics and six pesticides. In the case of analysis of the PC-CIP interaction using a CD spectrophotometer the α-helix content of PC decreased in the presence of CIP, which is an indication of conformational changes in the secondary structure of PC. Moreover, the molecular docking analysis of the PC-CIP interaction assisted in locating the three sites where CIP binds with CIP, which in turn provided additional instances of the interaction mechanism between PC and CIP.

环丙沙星 (CIP) 是一种常见的药物污染物，其残留量经常在环境中被检测到。在目前的工作中，CIP 在水环境中基于一种称为藻蓝蛋白 (PC) 的天然荧光化合物进行了研究。使用分光荧光光度计，进行 CIP 的荧光检测，并使用紫外可见分光光度计研究吸光度特性。此外，还实施了圆二色 (CD) 分光光度计和分子对接分析以进行进一步研究。荧光测量结果表明，随着 CIP 的添加量增加，终浓度为 0 至 120 μmol/L，PC 的荧光强度呈线性下降，检测限低至 95 nM。此外，当针对其他六种抗生素和六种杀虫剂进行测试时，发现荧光传感器对 CIP 更具选择性。在使用 CD 分光光度计分析 PC-CIP 相互作用的情况下，PC 的 α-螺旋含量在 CIP 存在下降低，这表明 PC 二级结构的构象发生变化。此外，PC-CIP 相互作用的分子对接分析有助于定位 CIP 与 CIP 结合的三个位点，这反过来又提供了 PC 和 CIP 之间相互作用机制的更多实例。