Aqueous zinc-ion batteries (AZIBs) hold great promise for large-scale energy storage, yet their practical application is hindered by dendrite growth, corrosion, and hydrogen evolution at the Zn anode. Carbon dots (CDs) are attractive coating materials for anode protection owing to their abundant zincophilic functional groups; however, their spontaneous aggregation into densely packed layers buries these groups and blocks ion-transport pathways, compromising their regulatory function. Herein, we resolve this dilemma via a zinc pre-embedding strategy: zinc pre-embedded carbon dots (zCD), synthesized through an ethanol-assisted solvothermal route, are coated onto Zn foil as a hydrophobic yet zincophilic protective layer (zCD@Zn). The pre-embedded Zn2+ acts as inter-particle spacers that suppress dense CD stacking, preserving continuous ion-transport channels while keeping the zincophilic groups accessible. The zCD layer thus shields the anode from water-induced parasitic reactions, reconstructs the Zn2+ solvation sheath (desolvation energy of 16.31 kJ/mol), and elevates the Zn2+ transference number to 0.79, collectively enabling uniform, dendrite-free Zn deposition. As a result, the zCD@Zn symmetric cell operates stably for over 1000 h at 1 mA/cm2 and 1 mA·h·cm−2, and Zn || Cu half cells deliver an average Coulombic efficiency of 99.5
Near-infrared (NIR) photoacoustic imaging (PAI) has become an important biomedical imaging technique because it integrates the high contrast of optical imaging with the deep penetration of ultrasound detection. Despite rapid progress, the development of efficient PAI contrast agents remains challenging, particularly in terms of strong NIR absorption, efficient non-radiative energy conversion, photothermal stability, biosafety, and clear structure-property relationships. Carbon dots (CDs), as emerging carbon-based nanomaterials with tunable optical properties, good biocompatibility, low toxicity, and abundant surface functional groups, provide a platform for PAI and image-guided photothermal therapy. In this review, we provide a brief introduction to the materials capable of generating photoacoustic (PA) signals, and then discuss the photothermal and photoacoustic mechanisms of CDs, as well as the relationship between them. We also summarize the biological applications of CDs in PAI, photothermal therapy (PTT), and photoacoustic/photothermal-guided multimodal combined diagnosis and treatment. Finally, we outline the challenges in this area and future prospects for their biomedical applications.
A time-resolved lateral flow immunoassay (LFIA) based on dual-emission carbon dots@silica nanospheres (CDs@SiO2) was developed for sensitive procalcitonin (PCT) detection. Fluorescent and room-temperature phosphorescent carbon dots were co-encapsulated in silica nanoparticles and conjugated with PCT antibodies to construct dual-signal immunoprobes. The long-lived phosphorescence effectively suppressed background interference and enabled visual qualitative detection, while the fluorescence signal allowed rapid quantitative analysis. Under optimized conditions, the assay exhibited a wide detection range, a low detection limit of 65 pg/mL, and negligible cross-reactivity with interleukin-6 and C-reactive protein. This dual-emission LFIA provides a rapid, sensitive, and specific approach for PCT detection and shows potential for point-of-care diagnosis of bacterial infections.
Near-infrared (NIR) photothermal agents are crucial for tumor therapy due to their unique ability to penetrate deep into tissues, overcoming the limitations of light scattering and absorption. In this study, we established a facile synthetic approach to extend the absorption range of carbon dots (CDs) into the NIR region via a self-oxidation mechanism. Using citric acid and uric acid as precursors, we prepared three types of CDs (WCDs, WACDs, and EACDs). Their oxidized forms (ox-WCDs, ox-WACDs, and ox-EACDs) exhibited broadened NIR absorption, attributable to an increased number of C=O groups. Among these, ox-EACDs exhibited superior performance with a remarkable photothermal conversion efficiency of 75.23
