**1. Introduction**

Biosensors are typical devices that convert biological signals into electrical signals, usually with high specificity regardless of pH and temperature, and can be divided into several types of sensors [1].

Biological sensors are generally composed of two parts, the first by the natural elements such as enzymes, cells, DNA, antibodies, tissues, and others, and the other by transducers capable of converting interaction events between the biological parts into electrical, light signals, thermal, and others [2].

In addition to the diversity associated with the type of analyte detected by the biological part, biosensors also differ according to the principle of operation, which can be electrochemical, thermal, gravimetric, and optical, among others. For example, in an electrochemical biosensor, reactions are measured based on the current, voltage, or resistivity produced by the oxidation or reduction of molecules in the medium [3].

Quantum Dots (QDs) are classified as nanostructured semiconductors that are formed mostly by elements of periodic groups II–VI, III–V, and IV–VI. Due to their zero-dimensional nature and smaller size compared to their excitation Bohr radius, they exhibit various optical, electric, and magnetic properties, among

others. These unique characteristics make them highly valuable and applicable in several areas [4–6].

QDs attract attention for their optical properties, activities, and applications in the electrical field. Due to the controlled variation of the *Gap* between its valence and conduction bands, its electronic properties can be explored in several ways, such as in the evaluation of charge transport, photocatalysis, electrochemiluminescence, conversion of light into electrical energy, among others [7–9].

An important technique that unites QDs and electrosensory is electrochemiluminescence, which combines spectroscopy and electrochemistry, allowing the electronic excitation caused by light on the QD to generate currents measurable by equipment, which can be used as on/off switches on the surface of electrodes or in reactions that use molecules marked with these semiconductors [10].

Although mechanisms based on optical detection, such as Fluorescence Resonance Energy Transfer (FRET), fluorescence, and Chemiluminescent Resonance Energy Transfer (CRET), have already been widely studied, the use of quantum dots (QDs) in the field of photoelectrochemical sensors is relatively new. However, it has garnered significant attention due to its remarkable optoelectric properties and potential applications in various fields, including diagnostic medicine [11–13].
