*Article* **A Novel Photoelectrochemical Aptamer Sensor Based on CdTe Quantum Dots Enhancement and Exonuclease I-Assisted Signal Amplification for** *Listeria monocytogenes* **Detection**

**Liangliang Zhu 1, Hongshun Hao 1,2,\*, Chao Ding 1, Hanwei Gan 1, Shuting Jiang 1, Gongliang Zhang 2, Jingran Bi 2, Shuang Yan 1 and Hongman Hou 2**


**Abstract:** To achieve the rapid detection of *Listeria monocytogenes*, this study used aptamers for the original identification and built a photoelectrochemical aptamer sensor using exonuclease-assisted amplification. Tungsten trioxide (WO3) was used as a photosensitive material, was modified with gold nanoparticles to immobilize complementary DNA, and amplified the signal by means of the sensitization effect of CdTe quantum dots and the shearing effect of Exonuclease I (Exo I) to achieve high-sensitivity detection. This strategy had a detection limit of 45 CFU/mL in the concentration range of 1.3 × 101–1.3 × 10<sup>7</sup> CFU/mL. The construction strategy provides a new way to detect *Listeria monocytogenes*.

**Keywords:** photoelectrochemical detection; aptamer; *Listeria monocytogenes*; quantum dots; exonuclease I
