Nitrogen-phosphorus co-doped carbon dots (NP-CDs) were prepared by a one-step hydrothermal method in the presence of triethylenetetramine and phosphoric acid using corn whiskers as a carbon source. A paper-based phosphorescent probe, NP-CDs@matrix@paper, with a room-temperature green phosphorescence afterglow lasting up to 8s was constructed by using the rigid environment provided by boric acid and urea. Oxytetracycline (OTC) not only enhances the intensity of the phosphorescence of the probe, but also exhibits a dynamic change from yellow phosphorescence to green phosphorescence discernible by the naked eye, which creates a favorable condition for visual detection of OTC. A series of optical properties were investigated to further reveal the interaction mechanism between the probe and OTC. The limit of detection (LOD) of the NP-CDs@matrix@paper probe for OTC is 1.17 µM. The results of sample analysis by using this probe are in high agreement with those obtained by using the national standard method. In this work, a long-life, paper based, color-changing room-temperature phosphorescent probe is developed from biowaste.

Carbon dots (CDs) synthesized from natural precursors with excellent fluorescent properties are drawing a lot of attention for sensing and biosensing applications. We offer a sustainable carbon precursor derived from Aloe veragel, utilizing a green one-step hydrothermal synthesis of carbon dots. A systematic optimization of the synthesis parameters was conducted by varying the reaction temperature, ranging from 180°C to 240°C in a 20°C interval, while adjusting the reaction duration (4, 8, 12, and 16h). We studied the absorption and emission of the prepared CDs using optical characterizations, such as UV-Vis and photoluminescence spectroscopy. X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy were used to study the structure and shape of the dots. These tests confirmed the creation of uniformly dispersed, amorphous, and functionalized carbon dots. The quantum yield and time-resolved PL decay were used in the determination of the most optimal synthesis conditions, yielding the highest photoluminescence quantum yield (PLQY) at 240°C and 12h. Results show that the synthesis parameters have a clear impact on the quantum yield, absorption, photoluminescence (PL) spectra, and morphology. CDs synthesized at 240°C for 12h with a carbon-to-oxygen ratio of Rc/o ≈ 2.37 showed the highest PLQY and were selected as sensitive fluorescence probes. As a first CDs powder-state temperature probe, the PL-intensity decrease from 298 to 393K evidence strong thermal responsivity over a wide range. The fluorescence works as a pH sensor by changing the emission-intensity ratio across pH 3-12 with two calibration lines. For metal-ion sensing, the CDs exhibit outstanding selectivity toward Fe³⁺ with near-complete PL quenching and a linear range 0-500 nM. Notably, the limit of detection (LOD) is 16.15 nM, the lowest among hydrothermally synthesized carbon dots (CDs) from natural precursors.

Abstract Depletion of natural resources and the growing energy usage for air conditioning in buildings necessitate energy-efficient window technologies that minimize power consumption and ultraviolet (UV) exposure, especially in the UV-A region. Herein, we report a silver-free hybrid nanocomposite coating composed of cesium-doped tungsten oxide nanoparticles (CWO NPs) and metal-free carbon dots (CDs) for simultaneous solar heat and UV-A shielding. The incorporation of CDs induces aggregation of CWO NPs, converting a dense nanoparticle film into a highly porous CWO–CD film that enhances solar absorption and scattering. By tuning film thickness and morphology, the CWO–CD coatings achieved 85% UV-A blocking and 92% near-infrared (NIR) shielding. Comparative tests using a laboratory-scale miniature house model under constant solar illumination revealed that the coated glass exhibited lowered temperatures by up to 12 °C compared to uncoated glass. This work introduces a silver-free, hybrid nanocomposite as an energy-saving coating for window and skylight applications.

Carbon Dots and mesoporous silica nanocomposites improve spray-induced gene silencing to suppress plant RNA and DNA viruses.

Visual memristors, which integrate resistive switching with optical feedback, are attracting growing interest for neuromorphic computing, nonvolatile storage, and human-machine interfaces. By directly coupling electrical states with optical outputs, such devices enable both data processing and intuitive visualization, providing new opportunities for interactive and multifunctional systems. Here, we innovatively demonstrate a carbon dot (CD)-based visual memristor that combines reliable resistive switching with tunable electroluminescence. The device exhibits stable storage, reproducible hysteresis loops, and multilevel conductance control, while its emission spectra systematically evolve with resistive states, enabling "visible" memory and computation. This dual-mode behavior bridges the electrical and optical domains, closely resembling synaptic plasticity and supporting artificial neuromorphic functions. Benefiting from the unique properties of CDs, including strong luminescence, abundant surface functionalities, and facile solution processing, the proposed device represents a new platform for multifunctional optoelectronic systems. These results open pathways toward next-generation neuromorphic optoelectronics that unify perception, memory, and processing.

In this study, a dual-ratiometric optical probe utilizing europium-doped carbon dots (Eu-CDs) was developed for simultaneous fluorescent and colorimetric detection of tetracycline (TC). The Eu-CDs complex was synthesized through a hydrothermal approach. Upon coordination with Eriochrome Black T (EBT), the Eu-CDs complex exhibits a distinct magenta coloration. Introduction of TC triggers a ligand displacement reaction, resulting in color transition from magenta to blue, resulting in ratiometric colorimetric visual detection. Meanwhile, the TC-bound EBT-CDs@Eu complex emits ratiometric fluorescence change. A ratiometric fluorescence detection method was established for TC based on the absorbance-energy transfer-emission (AETE) mechanism, culminating in the successful design of a dual-ratiometric optical probe. The colorimetric assay demonstrated a detection limit (LOD) of 20.5 nM for TC. Furthermore, the practical applicability of this sensor was validated through successful TC detection in aquaculture samples, highlighting its potential for real-world monitoring applications.

Nitrite, as a widely present nitrogen oxide compound in nature, and is extensively distributed in production and daily life; precise and rapid detection of it is of great significance for ensuring human health. This study developed nitrogen-doped carbon dots (N-CDs) using malic acid and 3-diethylaminophenol as precursors by one-step hydrothermal treatment. The obtained N-CDs exhibited strong green fluorescence with a high quantum yield of 20.86%. More importantly, they served as a highly effective fluorescent probe for NO2− sensing, demonstrating a low detection limit of 28.33 μM and a wide linear response range of 400 to 1000 μM. The sensing mechanism was attributed to an electrostatic interaction-enhanced dynamic quenching process. Notably, the probe enabled dual-mode detection: a distinct color change from light pink to dark brown under daylight for visual semi-quantification, and quantitative fluorescence quenching. The N-CDs showed excellent selectivity over common interfering ions. Furthermore, their low cytotoxicity and good biocompatibility allowed for successful bioimaging of exogenous and endogenous NO2− fluctuations in live HeLa cells. This work presents a facile green strategy to synthesize multifunctional N-CDs that realized the sensitive, selective, and visual detection of NO2− in environmental and biological systems.

Controlled and sustained antibiotic delivery is critical for combating antimicrobial resistance while minimizing side effects. Herein, a novel biodegradable hydrogel system, synthesized via gamma irradiation, incorporating fluorescent carbon dots (CDs) as multifunctional nano-crosslinkers, has been reported. The CDs, prepared from sustainable bio-precursors, reinforced the polymer network and enhanced the mechanical stability and swelling behavior, while simultaneously serving as intrinsic fluorescent probes for potential real-time monitoring of degradation and drug release. Thorough characterization revealed consistent morphology, adjustable biodegradability, and enhanced rheological characteristics. Drug release investigations demonstrated a diffusion-controlled mechanism, wherein the integration of CD diminished the cumulative antibiotic release from approximately 70% to approximately 40%, thereby facilitating precise regulation of release kinetics. The single-step gamma irradiation method facilitates concurrent crosslinking and sterilization, providing an efficient and scalable production strategy. This study presents a multifunctional hydrogel platform that integrates sustainable nanomaterials, regulated drug administration, and real-time monitoring, thereby facilitating the development of advanced theragnostic systems.

AI-assisted near-infrared ratiometric fluorescent sensor for ultrafast and portable visual detection of Bacillus anthracis biomarkers.

Reactive oxygen species (ROS) are being explored as a potential treatment, but accurate assessment of their efficacy is hindered by the dual roles of therapeutic intervention and diagnostic monitoring. Especially, ROS can alter lysosomal polarity by increasing membrane permeability. Therefore, ROS generation can be evaluated by monitoring the polarity changes of lysosomes. Hence, in this study, we developed a new lysosomal polarity-responsive carbon dot nanozyme (LF-CDs) that exerts peroxidase-like (POD-like) activity under light irradiation for controllable generation of ROS and sensing of ROS levels via lysosomal polarity response. Western blot analysis revealed that LF-CDs induced adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation within cells through the generation of ROS, effectively regulating intracellular glucose metabolism. Importantly, the ROS produced by LF-CDs can cause lysosomal polarity variation and trigger a corresponding fluorescence change in LF-CDs, reflecting the generation of ROS and enabling in situ monitoring of the regulation of glucose metabolism by ROS. By combining photocatalytic property with fluorescence imaging, this work overcomes the limitations of traditional ROS monitoring, offering a new insight into the evaluation of the biological effects of ROS during therapeutic processes.

High performance and unique mechanism of carbon dots modified iron-copper bimetals for antibiotics degradation.

Long-wavelength emissive N-doped carbon dots as a fluorescent probe for sensitive detection of pyrophosphate and cellular imaging.

To develop a safe, efficient, water-soluble, and targeted antibacterial substance for medical applications, we synthesized carbon dots using citric acid and urea as precursors by a solvothermal method. We then coupled the carbon dots and lysozyme by using a simple 1-ethyl-3-(3'-dimethylaminopropyl) carbodiimide-N-hydroxysuccinimide (EDC-NHS) coupling method. After coupling, the carbon dots exhibited improved water dispersibility with particle sizes ranging from 12 to 20 nm. Notably, the highest carbon dot concentration associated with cytotoxicity increased from 2.5 to 5 mg/mL when coupled with lysozyme, implying that coupling could enhance the biocompatibility of carbon nanodots. Furthermore, coupled carbon dots extended the effective inhibition time against Streptococcus mutans from 12 to 36 h, compared to carbon dots alone. The improved biocompatibility and prolonged effective antibacterial duration highlight the potential of lysozyme-coupled carbon dots as a safe, efficient, and water-soluble antibacterial agent for a variety of oral healthcare and medical applications.

Abstract Organic dyes found in wastewater negatively affect human, animal, and environmental health; therefore, they must be removed. One of the most promising approaches to dye removal is photocatalysis, where catalysts use light to generate electron–hole pairs that react with water and dissolved oxygen to produce powerful reactive oxygen species for oxidative degradation. Conventionally, photocatalysts are semiconductor metal oxide nanoparticles; however, because of their large band gaps, they have poor electron–hole generation efficiencies. Here, we investigate the viability of carbon dots as alternative photocatalysts. Research shows that heteroatom doping and surface functionalisation can be used to modify their electronic structure, allowing them to effectively utilise a much wider range of the electromagnetic spectrum to more efficiently produce the needed reactive oxygen species. Unfortunately, the propensity of carbon dots to aggregate reduces their photocatalytic efficiency; however, this can be prevented through the use of support materials. Due to the ability to obtain strong interfacial interactions with carbon dots, polymers have been identified as suitable supports. In particular, non-conducting polymers have recently been shown to be quite useful, modifying the electronic structure of the composite system by acting as electron traps. Furthermore, polymers exhibit good sorption properties: adsorbing water and oxygen molecules to promote reactive oxygen species generation; adsorbing dye molecules to allow more efficient degradation; and adsorbing the degradation products, enabling a more holistic approach to dye removal. Graphical Abstract

Laryngeal squamous cell carcinoma (LSCC), a predominant subtype of head and neck squamous cell carcinoma (HNSCC), exhibits notably high incidence and mortality rates worldwide. Despite the common use of surgery and radiation, patients with advanced or metastatic disease often have poor 5-year survival outcomes. Hence, there is a strong necessity to devise new treatments for intervention purposes. Polyphenolic compounds, such as quercetin (Que), have shown promise in cancer treatment, but their clinical application is hindered by their low solubility and bioavailability. In this study, we successfully synthesized a novel class of carbon dots (CDs) utilizing Que molecules as precursors through a one-pot hydrothermal method, resulting in marked enhancements in solubility and bioavailability. The Que-CDs created demonstrated significant impacts on stopping the growth, migration, and invasion of TU686 cells, while also encouraging cell cycle arrest and apoptosis. Transcriptomics analysis further revealed alterations in cell cycle regulation and apoptosis-related pathways. Importantly, in vivo experiments validated the antitumor efficacy of Que-CDs without causing damage to vital organs. These findings suggest that Que-CDs represent a safe and efficacious anticancer therapy for laryngeal cancer, meriting further investigation to explore their potential in clinical applications.

Cellulose nanocrystal (CNC) photonic films have emerged as sustainable alternatives to traditional pigments by harnessing cholesteric nanostructures for vivid, fade-resistant colors. However, scalable fabrication of continuously functionalized structural color patterns directly from CNC dispersion remains a grand challenge due to limitations in conventional printing techniques and coassembly approaches. Here, we present a bioinspired sequential nanofluidic-assisted photonic patterning (SNAPP) technique that leverages preformed cholesteric CNC films with three-dimensional helical nanochannels as self-regulated pathways for spontaneous ink diffusion. Mimicking nature's helical Venturi effect, this technique enables universal integration of diverse functional components (molecules, polymers, and nanoparticles) to manipulate photonic band gaps or impart stimuli-responsive functionalities while preserving long-range chiral order. By combining mask-guided patterning with capillary-driven transport, we achieve full visible-spectrum structural colors, humidity/thermal-responsive patterns, and fluorescent carbon dot integration with 4-fold enhanced emission intensity and circularly polarized luminescence. The resulting films retain angle-dependent iridescence and polarization selectivity, while exhibiting exceptional environmental stability, biocompatibility, and degradability. This multifunctional platform enables dual-channel optical encryption with orthogonal authentication modes (structural color, fluorescence, thermochromism, and circular polarization), positioning it as a high-security anticounterfeiting solution for pharmaceutical applications. The SNAPP technique overcomes the fundamental limitations of traditional methods, offering a scalable, versatile route to functional photonic materials with programmable dynamic responses.

The detection of ferric ions (Fe3+) is of crucial importance in environmental monitoring and biomedical diagnostics. However, developing highly selective, sensitive, and environmentally friendly detection methods remains an important challenge. In this study, nitrogen-doped carbon quantum dots (N-CQDs) were green-synthesized as a novel and sustainable fluorescent sensor for Fe3+ detection. The synthesis was achieved via a one-pot hydrothermal method using licorice powder as a renewable carbon source and p-phenylenediamine as a nitrogen dopant. The synthesized N-CQDs display bright blue fluorescence, with a maximum emission at 436nm when excited at 320nm. They serve as a highly selective and sensitive fluorescent probe for Fe3+, showing a distinct fluorescence "turn-OFF" response. The sensor offers a linear range of 0 to 50 µM for Fe3+ detection, with a calculated limit of detection (LOD) of 0.346 µM. A notable aspect of this work is the demonstration of an "ON-OFF-ON" sensing paradigm. The fluorescence quenched by Fe3+ can be effectively restored ("turn-ON") by adding ascorbic acid, which reduces Fe3+. This "ON-OFF-ON" behavior emphasizes the specificity of N-CQDs towards Fe3+ to Fe2+. The practical applicability of the sensor was confirmed through successful detection of Fe3+ in complex real-world samples, including beer and human blood serum, achieving excellent recovery percentages (97.6% - 101.7%) and low relative standard deviations (RSD, 0.9% - 1.8%). Overall, this research presents an environmentally friendly N-CQD-based fluorescent sensor with a unique reversible fluorescence response "ON-OFF-ON" for Fe3+, holding great potential applications in environmental monitoring and biomedical diagnostics.

There is an urgent need for strategies that enable the rapid synthesis of long-wavelength fluorescent carbon dots(CDs). In forensic science, the development and analysis of latent fingerprints (LFPs) are vital for criminal investigations. This process involves two steps: enhancing LFP visualization for better detectability and using digital processing techniques for accurate database comparisons. Long-wavelength-emitting CDs can significantly improve LFP visualization by enhancing contrast and minimizing background interference. This study focuses on synthesizing dual green/red-emissive nitrogen and iron co-doped carbon dots (N, Fe-CD green/red) using microwave-assisted methods. These N, Fe-CD green/red were integrated into a plaster and starch composite, resulting in N, Fe-CD green/red @plaster-starch phosphors. The phosphors effectively enhanced LFP development through dusting techniques. Under blue/green light excitation, the emitted green/red fluorescence from the N, Fe-CD green/red significantly improved LFP visualization, proving their usefulness in forensic applications. Additionally, artificial intelligence (AI) algorithms were utilized to analyze fluorescence images of developed LFPs, achieving match scores exceeding 73.0%, which indicates a high similarity to control references. These findings highlight the AI algorithms' effectiveness in reliably identifying and comparing fingerprint features.

Fabrication of N, S Co-doped carbon dot-sodium alginate hydrogel for efficient recovery of rare earth ions from wastewater.

ABSTRACT The environmental pollution caused by non‐degradable polymer is becoming more and more serious. Polyvinyl alcohol (PVA), biodegradable, non‐toxic, is a good substitute. However, pure PVA has single function, low mechanical strength, poor thermal stability and poor water resistance, which limits its wide application range. Carbon dots (CDs) as a new member of the carbon family has many outstanding advantages such as non‐toxic, low‐cost and becomes an important modifying substance for PVA. CDs/PVA composites show some new properties, such as shape memory, electrochemical properties, optical properties, antibacterial, ultraviolet blocking, which greatly expands its application fields. This review focuses on some novel applications of CDs/PVA. For instance, the ability to form reversible dynamic bonds make CDs/PVA suitable for shape memory and self‐healing materials. The excellent luminescent characteristics and high photoluminescence quantum yield of CDs confer optical properties to CDs/PVA, enabling new applications in optoelectronics and sensing fields. Due to its water resistance, antibacterial properties, antioxidant capacity, and UV resistance, CDs/PVA can serve as a new functional packaging material. Other applications include as adsorbent in environmental protection, anti‐counterfeiting materials, fingerprint identification, electromagnetic shielding materials, catalysis, energy storage, and more. Some bottleneck and challenging issues are also discussed to provide guidance for future research.