In 2004, Xu
et al. serendipitously discovered and reported the existence of fluorescent nanoparticles during the purification of single-walled carbon nanotubes through gel electrophoresis [
14]. Subsequently, in 2006, Sun
et al. employed laser ablation of “carbon targets” derived from graphite powder and cement, augmenting the photoluminescence of carbon nanoparticles
via surface passivation with polyethylene glycol (PEG) [
15]. This pioneering approach led to the nomenclature of the resultant carbon nanoparticles as “carbon dots (CDs)” for the first time. CDs are zero-dimensional carbon nanoparticles smaller than 10 nm with a passivated surface and intense fluorescence [
16]. Typically, CDs exhibit amorphous or nanocrystalline nuclei that are predominantly composed of sp
2-hybridized carbon. CDs can be categorized into three principal types based on the nature of their carbon nuclei: graphene quantum dots (GQDs), carbon nanodots (CNDs), and carbon polymer dots (CPDs). GQDs derived from graphene and/or graphene oxide possess morphological characteristics that mimic both CDs and graphene, affording GQDs with similar physical and chemical properties to graphene [
17-
19]. CNDs are surface-passivated carbon nanomaterials, typically less than 10 nm in size, displaying a discrete quasi-spherical morphology. Unlike GQDs, they are anisotropic with lateral dimensions exceeding their height [
20]. CPDs are cross-linked products obtained through the dehydration condensation and carbonization of polymer precursors, featuring a “core-shell” nanostructure, where the carbon core and attached polymer chains (shells) self-assemble into CPDs [
21]. Functioning as an amalgamation of semiconductor quantum dots and carbon materials, CDs combine the advantages of both. Compared to traditional semiconductor quantum dots and organic dyes, CDs exhibit superior photostability, including resistance to photodegradation, high bleaching resistance, and light scintillation, coupled with high photoluminescence quantum yields. Additionally, CDs have low toxicity, abundant precursor sources, and excellent biocompatibility [
22-
33]. These distinctive features have propelled intensive research on CDs across diverse domains, including sensing, bioimaging, drug loading, phototherapy, catalysis, and environmental applications [
34-
43]. In order to better detect dopamine, most of the CDs currently used contain carboxyl groups, which have good stability and can interact with amine groups in dopamine through electrostatic interactions. In addition, the
π-
π stacking between CDs and DA enhances electron transfer and communication, effectively constructing CDs-based dopamine sensors [
9,
10]. Therefore, more and more researchers are constructing various novel dopamine sensors through the interaction between CDs and dopamine. A comprehensive literature search was conducted on the “Web of Science” spanning from 2013 to 2023, utilizing the keywords “carbon dots”, or “graphene quantum dots”, or “carbon nanodots”, or “carbon polymer dots” and “dopamine detection”. The analysis revealed a steady rise in publications pertaining to the utilization of CDs for dopamine detection, particularly from 2015 onwards, underscoring the significant promise of CDs in dopamine detection (Fig. S1 in Supporting information). Furthermore, CDs are frequently used with other materials to formulate high-performance carbon-dot-based composites, enhancing the efficiency of dopamine detection for rapid, sensitive, and highly specific outcomes. This paper comprehensively reviews the applications of CDs in dopamine detection, focusing on three facets: electrochemical, fluorescent, and colorimetric sensors. In addition, the future directions and prospects of carbon-dot-based nanomaterials for diverse applications are discussed.