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Oxytetracycline (OTC) is an environmental pollutant caused by the abuse of antibiotics, and its content in water is closely related to human health. Therefore, the development of a simple, rapid, and accurate method to detect OTC has become desirable. In this work, a ratiometric fluorescence probe based on deep red emissive CdTe quantum dots (QDs) modified by mercaptopropionic acid and Eu3+ is developed to accurately and rapidly detect OTC in water. After the addition of OTC, the photoluminescence intensity of CdTe QDs at 698 nm remains almost unchanged, while the peak at 617 nm intensifies within 40 s due to the coordination of Eu3+ with OTC. An excellent linear relationship is present between the photoluminescence intensity ratio of I617/I698 and the concentration of OTC. The limit of detection of the probe towards OCT is 5.4 nM. In addition, the probe shows good selectivity and anti-interference ability for OTC in the presence of other antibiotics, including other antibiotics, ions, and amino acids. The probe has been successfully applied to detect OTC in actual samples, demonstrating its potential for environmental application. [ABSTRACT FROM AUTHOR]

Lysosome targetable carbon dots which can simultaneously generate 1O 2 , OH and heat under 635 nm laser irradiation were prepared, their applications in photothermal/photodynamic synergistic cancer therapy and photoacoustic/two-photon excited fluorescence imaging were demonstrated. • Carbon dots with lysosome targeting ability was prepared. • The carbon dots exhibited negligible toxicity. • The multimodality imaging of carbon dots could be applied for diagnosis. • A highly efficient photothermal-photodynamic phototherapy of cancer was performed. Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT) holds great potential for efficient cancer therapy by inducing reactive oxygen species (ROS) or heat into tumor. Nevertheless, PDT or PTT suffers from some limitations, e.g., PTT requires long-time and high-power laser irradiation to generate enough heat, while the hypoxia microenvironment of tumor and the limit diffuse distance of ROS hamper the efficacy of oxygen-dependent PDT. Here we reported the carbon dots (CDs) which could simultaneously generate singlet oxygen (1O 2), hydroxyl radical (OH), and heat under a 635 nm laser irradiation, with a 1O 2 generation quantum yield of 5.7% and photothermal conversion efficiency of 73.5% (the highest thus far for CDs). Significantly, the CDs can selectively accumulate in lysosome, which is an ideal organelle for phototherapy because of its key role in sustaining cellular activity and stability. Moreover, the CDs present one-photon excited (OPE) and two-photon excited (TPE) fluorescence, and excellent photoacoustic (PA) imaging capability. Combining the good biocompatibility, the as-prepared CDs was served as multi-functional phototheranostic agent for synergistic PA/fluorescence imaging, and PDT/PTT. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) with blue fluorescence were synthesized through hydrothermal treatment of p -dihydroxybenzene and hydrazine hydrate. The fluorescence of the investigated CDs could be selectively quenched by iron ions (Fe3+) because of the strong metal-ligand coordination and electrostatic interactions between the large amount of hydroxyl, amino, and carboxyl groups on CDs' surface and Fe3+. Interestingly, this non-fluorescent CDs + Fe3+ complex displayed a sensitive and selective turn-on fluorescence toward ampicillin with a limit of detection of 0.70 μM. The sensing process could be observed by naked eyes under the 365 nm UV light irradiation. Importantly, CDs + Fe3+ complex had been successfully applied in the detection of ampicillin in river water. • Fluorescent CDs were synthesized through hydrothermal treatment of p -dihydroxybenzene and hydrazine hydrate. • The fluorescence of CDs was quenched significantly and quickly upon addition of Fe3+. • The quenched fluorescence of CDs could be selectively turned on by the addition of ampicillin. • The CDs-Fe3+ system was successfully applied in the ampicillin detection in river water. [ABSTRACT FROM AUTHOR]

[Display omitted] • A CDs@LP with fluorescence and ultra-long (lifetime of 1.33 s) RTP were prepared. • The dual-responsive probe provide a novel strategy for accurate OTC detection. • Fluorescence and RTP test strip was successfully used to analyze OTC. • The dual-signal probe exhibit low LOD and good recovery rate in actual water samples. Dual-responsive probes emitting both fluorescence and phosphorescence signals are greatly advantageous to sensing. Here, we present a carbon dots-based luminophore (CDs@LP) with blue fluorescence and ultra-long yellow room-temperature phosphorescence (RTP) with lifetime of 1.33 s (that was visible to the naked eye for ∼ 13 s) for ratiometric detection of oxytetracycline (OTC). The CDs@LP was prepared by molten salt method through one-step treatment of 2, 6-diaminopyridine, KNO 3 , MgCl 2 , and KH 2 PO 4. Upon the addition of OTC into CDs@LP aqueous solution, the fluorescence at 386 nm and RTP at 538 nm of CDs@LP were quenched as a result of the inner filter effect (IEF), while the fluorescence at 522 nm of OTC steadily enhanced due to the molecular restriction through the formation of OTC-Mg2+ complexes. Both fluorescence and RTP signals have excellent linear relationships with OTC concentration. The CDs@LP had a low detection limit of 3.2 nM (fluorescence) and 0.27 μM (phosphorescence), which also exhibited satisfactory selectivity and anti-interference performance towards other antibiotics. Moreover, the CDs@LP was successfully loaded on a filter paper and used for OTC sensing. Thus, it is a promising tool for OTC detection and can act as a foundation for producing dual-signal sensing tools. [ABSTRACT FROM AUTHOR]

• The luminescence mechanisms of NIR CDs are introduced in detail. • The synthesis strategies of NIR CDs are discussed. • The biomedical applications of NIR CDs are elaborated. • A future perspective toward synthesis and application of NIR CDs is described. Carbon dots (CDs) are widely used in biomedical imaging and cancer therapy due to their excellent water solubility, low toxicity, satisfying biocompatibility, and good tissue permeability. Among them, near-infrared (NIR) fluorescent CDs (λ em > 650 nm) could effectively avoid the interference of spontaneous biological fluorescence, have strong tissue penetration ability, which can realize high-resolution fluorescence imaging of deep tissues, and hence show great potential in the biomedical field. Therefore, the controlled synthesis and regulation the photochemical and photophysical properties of NIR fluorescent CDs has also become a research hotspot. This review aimed to systematically summarize the synthesis strategies, luminescence mechanisms, and biomedical applications of NIR fluorescent CDs in the last 10 years. The challenges and perspectives in the synthesis and applications of NIR fluorescent CDs were also discussed. [ABSTRACT FROM AUTHOR]

Unveiling the dynamics of intracellular hypochlorite (ClO-) and polarity during ferroptosis is essential for understanding the role of ferroptosis in the development of related diseases. Herein, dual-ratiometric fluorescent probes, PTZ-PY , PTZ-IN and PTZ-QL , were developed for simultaneous detection of ClO- and polarity with high sensitivity and good selectivity. Under single-wavelength excitation, the exemplified probe PTZ-QL displayed distinctive fluorescence changes in response to ClO- and polarity alterations: red to green fluorescence change in response to ClO-, and red to orange fluorescence change in response to decreased polarity. The preliminary biological applications using probe PTZ-QL were successfully applied to image the increase in the concentration of ClO- and the increase in the polarity during ferroptosis. [Display omitted] • The probes showed dual-ratiometric fluorescence responses toward ClO- and polarity. • Probe PTZ-QL demonstrated a potential for imaging ClO- and polarity during ferroptosis. • The probes displayed good selectivity and high sensitivity. [ABSTRACT FROM AUTHOR]