Cefixime is a third generation orally administered cephalosporin that is frequently used as a broad spectrum antibiotic against various gram-negative and gram-positive bacteria. In this study, a simple and sensitive fluorescent sensor for the determination of the cefixime and ctDNA was established based on the CdTe:Zn2+ quantum dots (QDs). The fluorescence of CdTe:Zn2+ QDs can be effectively quenched by cefixime in virtue of the surface binding of cefixime on CdTe:Zn2+ QDs and the subsequent photoinduced electron transfer process from CdTe:Zn2+ QDs to cefixime, in particular, the high sensitivity of QDs fluorescence emission to cefixime at the micromole per liter level, which render the cefixime-CdTe:Zn2+ QDs system into fluorescence "OFF" status, then turn on in the presence of ctDNA. Furthermore, the Fourier transform infrared (FTIR) spectra of characteristic bands of C-N and N-H groups of cefixime endow evidence for the interaction of cefixime with CdTe:Zn2+ QDs. The relative electrochemical behavior of the affinity of CdTe:Zn2+ QDs for cefixime and ctDNA reveals the potential molecular binding mechanism.

中文翻译：

---

基于头孢克肟和ctDNA的光诱导电子转移机制的灵敏荧光传感器。

头孢克肟是第三代口服头孢菌素，经常用作针对各种革兰氏阴性和革兰氏阳性细菌的广谱抗生素。在这项研究中，基于CdTe：Zn2 +量子点（QDs）建立了一种简单而灵敏的荧光传感器，用于测定头孢克肟和ctDNA。头孢克肟可以通过头孢克肟有效地终止CdTe：Zn2 + QDs的荧光，因为头孢克肟在CdTe：Zn2 + QDs上的表面结合以及随后的光诱导电子从CdTe：Zn2 + QDs到头孢克辛的电子转移过程，特别是QDs荧光的高灵敏度以微摩尔每升水平向头孢克肟发射，这使头孢克肟-CdTe：Zn2 + QDs系统变成荧光“ OFF”状态，然后在存在ctDNA的情况下开启。此外，头孢克肟CN和NH基团特征带的傅里叶变换红外（FTIR）光谱提供了头孢克肟与CdTe：Zn2 + QDs相互作用的证据。CdTe：Zn2 + QDs对头孢克肟和ctDNA的亲和力的相对电化学行为揭示了潜在的分子结合机理。