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Safe and efficient local anesthetic delivery carriers are crucial for long-term anesthesia and analgesics in clinical treatment. But currently, most of the local anesthetic carriers still have some disadvantages such as low drug-loading capacity, drug leakage, and potential side effects. Here, we report red-emissive carbon dots (Cys-CDs) synthesized by choosing cysteine and citric acid as precursors, which contain a large and intact sp 2 -domain with rich hydrophilic groups around the edge. The special structure of Cys-CDs is conducive to the efficient loading of procaine (PrC) via strong π-π stacking interactions. Based on the strong noncovalent interactions between them, the PrC loaded on Cys-CDs achieved slow release in vitro and had a long-lasting nerve blocking effect in vivo, which is 4-fold more than that of free PrC. More importantly, PrC/Cys-CDs do not cause any toxicity and inflammation during treatment owing to slow release of PrC and good water solubility of Cys-CDs, thus demonstrating the potential clinical application of CDs in long-lasting analgesia.

Strategies for selectively imaging and delivering drugs to tumours typically leverage differentially upregulated surface molecules on cancer cells. Here, we show that intravenously injected carbon quantum dots, functionalized with multiple paired α-carboxyl and amino groups that bind to the large neutral amino acid transporter 1 (which is expressed in most tumours), selectively accumulate in human tumour xenografts in mice and in an orthotopic mouse model of human glioma. The functionalized quantum dots, which structurally mimic large amino acids and can be loaded with aromatic drugs through π-π stacking interactions, enabled-in the absence of detectable toxicity-near-infrared fluorescence and photoacoustic imaging of the tumours and a reduction in tumour burden after the targeted delivery of chemotherapeutics to the tumours. The versatility of functionalization and high tumour selectivity of the quantum dots make them broadly suitable for tumour-specific imaging and drug delivery.

Large doses of anticancer drugs entering cancer cell nuclei are found to be effective at killing cancer cells and increasing chemotherapeutic effectiveness. Here we report red-emissive carbon quantum dots, which can enter into the nuclei of not only cancer cells but also cancer stem cells. After doxorubicin was loaded at the concentration of 30 μg/mL on the surfaces of carbon quantum dots, the average cell viability of HeLa cells was decreased to only 21%, while it was decreased to 50% for free doxorubicin. The doxorubicin-loaded carbon quantum dots also exhibited a good therapeutic effect by eliminating cancer stem cells. This work provides a potential strategy for developing carbon quantum-dot-based anticancer drug carriers for effective eradication of cancers.

The IR780 iodide (IR780) is recognized as an effective theranostic agent for simultaneous near-infrared fluorescence imaging and photothermal therapy (PTT). However, the rigid chloro-cyclohexenyl ring makes IR780 insoluble in almost all pharmaceutically acceptable solvents, which inevitably limits its clinical application. We report folic acid (FA)-functionalized graphene quantum dots (GQDs-FA) containing a large and intact sp 2 domain with carboxyl groups around the edge. Such GQDs-FA possess exceptionally high loading capacity for IR780 via strong π-π stacking interactions, and the water solubility of IR780 is improved by over 2400-fold after loading onto GQDs-FA (IR780/GQDs-FA). IR780/GQDs-FA with an improved photostability, an enhanced tumor-targeting ability, and a high photothermal conversion efficiency of 87.9% were capable of producing sufficient hyperthermia to effectively kill cancer cells and completely eradicate tumors upon 808 nm laser irradiation. The present IR780/GQDs-FA may open up great opportunities for the effective PTT to treat cancer.

A turn-on orange-red fluorescent nanosensor based on rhodamine B derivative-functionalized graphene quantum dots (RBD-GQDs) has been successfully synthesized for Fe(3+) detection with high sensitivity and selectivity. By connecting with GQDs, the water solubility, sensitivity, photostability, and biocompatibility of RBD are drastically improved. The most distinctive feature of the RBD-GQDs, which sets them apart from other previously reported fluorophores or GQDs, is that they with the detection limits as low as 0.02 μM are demonstrated as a Fe(3+) turn-on fluorescent nanosensor in cancer stem cells. Fe(3+) binding to such GQDs (RBD-GQDs-Fe(3+)) with orange-red fluorescence of 43% quantum yield were demonstrated to be the biomarkers for cancer stem cell imaging.

We report water-soluble, 3 nm uniform-sized graphene quantum dots (GQDs) with red emission prepared by electrochemical exfoliation of graphite in K2S2O8 solution. Such GQDs show a great potential as biological labels for cellular imaging.

Sulfur-doped graphene quantum dots (S-GQDs) with stable blue-green fluorescence were synthesized by one-step electrolysis of graphite in sodium p-toluenesulfonate aqueous solution. Compared with GQDs, the S-GQDs drastically improved the electronic properties and surface chemical reactivities, which exhibited a sensitive response to Fe(3+). Therefore, the S-GQDs were used as an efficient fluorescent probe for highly selective detection of Fe(3+). Upon increasing of Fe(3+) concentration ranging from 0.01 to 0.70 μM, the fluorescence intensity of S-GQDs gradually decreased and reached a plateau at 0.90 μM. The difference in the fluorescence intensity of S-GQDs before and after adding Fe(3+) was proportional to the concentration of Fe(3+), and the calibration curve displayed linear regions over the range of 0-0.70 μM. The detection limit was 4.2 nM. Finally, this novel fluorescent probe was successfully applied to the direct analysis of Fe(3+) in human serum, which presents potential applications in clinical diagnosis and may open a new way to the design of effective fluorescence probes for other biologically related targets.

In this paper, we have elucidated the fundamental principle of employing CV to investigate the band structures of semiconductor nanocrystals (SNCs), and have also built up an optimal protocol for performing such investigation. By utilizing this protocol, we are able to obtain well-defined and characteristic electrochemical redox signals of SNCs, which allows us to intensively explore the influences of the particle size, the surface ligand and particle composition on the band structures of CdSe, CdTe and their alloy nanocrystals. The size-, ligand- and composition-dependent band structures of CdSe and CdTe nanocrystals (NCs) have therefore been mapped out, respectively, which are generally consistent with the previous theoretical and experimental reports. We believe that the optimal protocol and the original results regarding electrochemical characterization of SNCs demonstrated in this paper will definitely benefit the better understanding, modulation and application of the unique electronic and optical properties of SNCs.

Although power conversion efficiency (PCE) of solar cells (SCs) continues to improve, they are still far from practical application because of their complex synthesis process, high cost and inferior operational stability. Carbon quantum dots with high material stability and remarkable photoluminescence are successfully used in light‐emitting diodes. A good light emitter should also be an efficient SC according to the photon balance in Shockley–Quieisser formulation, in which all excitons are ultimately separated. However, the finite quantum‐sized sp2 domain leads to tight exciton bonding, and highly delocalized electron clouds in irregular molecular stacks form disordered charge transfer, resulting in severe energy loss. Herein, an axially growing carbon quantum ribbon (AG‐CQR) with a wide optical absorption range of 440–850 nm is reported. Structural and computational studies reveal that AG‐CQRs (aspect ratio ≈2:1) with carbonyl groups at both ends regulate energy level and efficiently separate excitons. The stacking‐controlled two‐dimensional AG‐CQR film further directionally transfers electrons and holes, particularly in AB stacking mode. Using this film as active layer alone, the SCs yield a maximum PCE of 1.22%, impressive long‐term operational stability of 380 h, and repeatability. This study opens the door for the development of new‐generation carbon‐nanomaterial‐based SCs for practical applications. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) feature bright and tunable photoluminescence, solution processability, and low toxicity, showing great potential in optoelectronics. However, the large‐scale synthesis of CQDs with near‐unity photoluminescence quantum yield (PLQY) has not been achieved so far. In this study, we perform radical‐assisted synthesis of hexagon‐shaped CQDs (H‐CQDs) delivering near‐unity PLQY (96 %). Experimental and theoretical analyses revealed that the large vertically oriented transition dipole moment of H‐CQDs originating from high symmetry results in nearly 100 % PLQY. The H‐CQDs also exhibited a high electron mobility of up to 0.07 cm2 V−1 s−1. These properties enable the H‐CQD‐based light‐emitting diodes with a high external quantum efficiency of 4.6 % and a record maximum brightness of over 11 000 cd m−2. This study represents a significant advance that CQDs‐based electroluminescent device can be utilized for potential display and lighting applications. [ABSTRACT FROM AUTHOR]

The negative impact of rare‐earth elements (REEs) on the environment, limited supply and high cost prompt the need for REE‐free phosphor‐converted white light‐emitting diodes (LEDs). Here, we report the gram‐scale synthesis of red/green/blue solid‐state bandgap fluorescent carbon quantum rings (R/G/B‐SBF‐CQRs) with high quantum yields up to 30–46 %. This was achieved using cyano‐group‐bearing p‐phenyldiacetonitrile as precursor and forming carbon quantum rings of different diameters through the linkage of curved carbon quantum ribbons of different lengths. The results show the role of cyano groups in inducing the curvature of the carbon quantum ribbons for CQR formation and emission of stable solid‐state bandgap fluorescence. R/G/B‐SBF‐CQRs‐phosphor‐based LEDs emitted warm white light with low CCT (3576 K), high CRI (96.6), and high luminous efficiency (48.7 lm W−1), comparable to REE‐phosphor‐based LEDs. [ABSTRACT FROM AUTHOR]

An ultrabroad-band solid white emission from carbon quantum dot aggregation with a full width at half maximum over 200 nm throughout the entire visible light window and, even better, with a sufficient red component is first reported. UV pumped WLEDs are fabricated by integrating phosphors onto a UV-LED chip, and they show favorable warm white light characteristics with CIE coordinates of (0.42, 0.38) and a 91 high color rendering index. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate that boron-doping of graphene quantum dots (B-GQDs) give rise to rich fluorescence owing to their peculiar interaction with the surrounding media. A B-GQDs borax (Na2B4O7·10H2O) solution was shown to be highly fluorescent in green, and upon evaporation, formed bright green fluorescent crystals. However, removing the borax left behind only blue and yellow luminescent solutions. These intriguing findings are rationalized by the insight that B-GQDs associate in the absence of borax whereas they form dative valence bonds with the bridgehead O atoms of borax in the presence of borax. We further demonstrate the use of the B-GQDs, for example, in chemosensor for detecting Al3+ and biomarker for cellular imaging. [Copyright &y& Elsevier]

The development of efficient red bandgap emission carbon quantum dots (CQDs) for realizing high‐performance electroluminescent warm white light‐emitting diodes (warm‐WLEDs) represents a grand challenge. Here, the synthesis of three red‐emissive electron‐donating group passivated CQDs (R‐EGP‐CQDs): R‐EGP‐CQDs‐NMe2, ‐NEt2, and ‐NPr2 is reported. The R‐EGP‐CQDs, well soluble in common organic solvents, display bright red bandgap emission at 637, 642, and 645 nm, respectively, reaching the highest photoluminescence quantum yield (QY) up to 86.0% in ethanol. Theoretical investigations reveal that the red bandgap emission originates from the rigid π‐conjugated skeleton structure, and the ‐NMe2, ‐NEt2, and ‐NPr2 passivation plays a key role in inducing charge transfer excited state in the π‐conjugated structure to afford the high QY. Solution‐processed electroluminescent warm‐WLEDs based on the R‐EGP‐CQDs‐NMe2, ‐NEt2, and ‐NPr2 display voltage‐stable warm white spectra with a maximum luminance of 5248–5909 cd m−2 and a current efficiency of 3.65–3.85 cd A−1. The warm‐WLEDs also show good long‐term operational stability (L/L0 > 80% after 50 h operation, L0: 1000 cd m−2). The electron‐donating group passivation strategy opens a new avenue to realizing efficient red bandgap emission CQDs and developing high‐performance electroluminescent warm‐WLEDs. [ABSTRACT FROM AUTHOR]

The development of ultrastable and low‐threshold random lasers has long been the subject of intense academic research, in anticipation for widespread applications spanning from military weapon devices, biomedical therapy, and materials processing to energy savings. Reported here is the first example of ultrastable and low‐threshold random lasing emissions ranging from blue to red based on narrow bandwidth emission triangular carbon quantum dots (CQDs). The lasing thresholds of the blue, green, and red random lasers are determined to be as low as 0.087, 0.052, and 0.048 mJ cm−2, and the corresponding narrow full widths at half maximum are 0.9, 0.37, and 0.82 nm, respectively. Furthermore, such random lasers demonstrate outstanding stability. This work will inspire further research on lasers operating in other modes, based on the CQDs, such as the whispering‐gallery mode and the Fabry–Pérot mode, which will expedite the development of the next‐generation of ultrastable and low‐threshold CQDs‐based laser technology. Ultrastable and low‐threshold random lasing emissions ranging from blue to red, based on narrow‐bandwidth‐emission triangular carbon quantum dots is reported. The lasing thresholds of the blue, green, and red random lasers are determined to be as low as 0.087, 0.052, and 0.048 mJ cm−2, respectively. [ABSTRACT FROM AUTHOR]