Search

Carbon dots (CDs) have gained significant interest because of their potential in biomedical applications. Nevertheless, developing CDs with efficient photoinduced charge separation for tumor photodynamic therapy (PDT) remains a challenge. This study presents a novel class of supra‐carbon‐dots (supra‐CDs) developed by fusing red emissive CDs with 2,3‐dicyanohydroquinone (DCHQ) via post‐solvothermal treatment. In supra‐CDs, the core, acting as electron donors, is formed by assembled CDs with substantial sp2 domains, the fused interface originating from DCHQ with electron‐withdrawing groups functions as the electron acceptor. This configuration creates the unique donor‐acceptor nanostructure. Upon white light irradiation, the excited electrons from the assembled CDs were transferred to the electron‐withdrawing interface, whereas the photogenerated holes were retained within the assembled CDs as radicals, leading to effective photoinduced charge separation. The separated photogenerated electrons then react with oxygen to generate superoxide radicals. Simultaneously, the photogenerated holes undergo oxidation of crucial cellular substrates. This dual action underscores the exceptional cell‐killing efficacy of supra‐CDs. Moreover, the increased particle sizes (~20 nm) ensure supra‐CDs to exhibit a notable capacity for tumor accumulation via the improved permeability and retention effect, thereby achieving satisfactory anti‐tumor PDT efficacy in a mouse subcutaneous tumor model. [ABSTRACT FROM AUTHOR]

Egg white (EW)‐derived hydrogels hold promise as biomaterials for in vitro cell culture due to their ability to mimic the extracellular matrix. However, their highly cross‐linked structures restrict their potential for in vivo applications, as they are unable to integrate dynamically with tissues before degradation. In this study, this limitation is addressed by introducing carbon dots (CDs) as cross‐linking agents for EW in a dilute aqueous solution. The resulting CDs‐crosslinked EW hydrogel (CEWH) exhibits tensile strength comparable to that of skin tissue and features a large pore structure that promotes cell infiltration. Subcutaneous implantation of CEWH demonstrated excellent integration with surrounding tissue and a degradation rate aligned with the hair follicles (HFs) regeneration cycle. This allows the long‐term regeneration and establishment of an M2 macrophage‐dominated immune microenvironment, which in turn promotes the re‐entry of HFs into the anagen phase from the telogen phase. Additionally, CEWH demonstrated potential as a wound dressing material. Overall, this study paves the way for utilizing EW as a versatile biomaterial for tissue engineering. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are highly desired in biological applications. However, achieving a balance between photoluminescence (PL) efficiency and photothermal conversion efficiency (PTCE) is challenging. In this study, an unprecedent combination of efficient red fluorescence and high PTCE in the second near‐infrared (NIR‐II) window in a sodium‐doped CDs system is reported. Upon 808 nm laser irradiation, photo‐induced oxidation–reduction reactions happened on the surface of sodium cation‐functionalized CDs (Na‐CDs), leading to the partial reduction of surface‐functionalized sodium (Na) ions. The photo‐reduced Na atoms coordinated with sp2 C domains in the core, resulting in Na‐doped CDs (ir‐Na‐CDs) with an enhanced absorption band in the NIR‐II window and a high PTCE of 43% under 1064 nm laser irradiation (1 W cm−2). Composing the ir‐Na‐CDs with bovine serum albumin (BSA) enhanced the PLQY of the red emission to 31% in water without diminishing the PTCE in the NIR‐II region. Transient absorption spectra revealed that no energy transfer occurred between the red emission center and the NIR‐II absorption band, revealing a novel CDs system with independent Janus photophysical processes. Moreover, ir‐Na‐CDs@BSA exhibited negligible to low cytotoxicity and demonstrated tumor accumulation capacity after intravenous injection, enabling effective tumor photothermal therapy in the NIR‐II region. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are a burgeoning star of luminescent carbon‐based nanomaterials with emerging interest for various applications. Luminescence from the sp2‐conjugated domains in the carbon cores is considered to be the intrinsic bandgap emission of CDs, whereas the relationship between them remains poorly understood. Simultaneously, the solvent relaxation of water molecules will quench the fluorescence of CDs, thus, obtaining strong luminescence from CDs aqueous solutions remains a great challenge. Herein, a facile one‐step spatial‐confined cross‐condensation method that uses a heat‐induced self‐foaming process in ambient pressure has been developed to synthesize highly luminescent CDs with unprecedented photoluminescence quantum yield (PLQY) over 97.2% in water. The unique precursor‐derived cross‐arranged perylene skeleton in the cores hinders π–π stacking, while the hydrophobicity of the conjugated units mitigates solvent relaxation by water molecules, resulting in near‐unity PLQY in aqueous solutions, enabling this to demonstrate the first optically pumped green lasing emission in the CDs aqueous solution. Moreover, a biomaterial‐based white light emitting diode is fabricated using the CDs‐stained silks as a fluorescence conversion cover to realize a high luminous efficiency of 60.7 lm W−1 with CIE color coordinate of (0.33, 0.35). [ABSTRACT FROM AUTHOR]

Achieving a stimulus-responsive, multi-colour, long-lived luminescence based on single-emissive-center carbon dots (CDs) is highly desirable for numerous promising applications. However, the fabrication of such materials remains a formidable challenge because of the limited paths of exciton transfer. Herein, we report a facile strategy to achieve a colour-tuneable afterglow by selectively activating different exciton transfer channels in a carbon dot–cyanuric acid (CA) composite (CD@CA) by alkali induction. Upon alkali treatment, CD@CA exhibited a noticeable afterglow colour change from cyan to yellow with an excellent reversible pH response. Remarkably, the yellow afterglow efficiency is as high as 34.8% and its average lifetime can reach 0.535 s. Detailed analyses revealed the existence of two exciton transport pathways within the system. Excitons can be transduced from CA to CDs via Förster resonant energy transfer, leading to a cyan afterglow. In an alkaline environment, this channel was destroyed, and the inherent phosphorescence exciton transport channel of CDs was simultaneously activated and enhanced. Alkali-induced CD ionization and the formation of rigid crystal networks boost intersystem crossing rates and reduce non-radiative transitions, resulting in a bright yellow afterglow. Furthermore, based on the colour-tuneable afterglow properties of the system, we illustrated the potential applications of CD@CA in advanced information encryption. This study provides guidance in the development of multi-colour afterglow materials with stimulus-responsive characteristics to meet the growing demand for highly secure information storage materials. [ABSTRACT FROM AUTHOR]

Nanohybrid photosystems have advantages in converting solar energy into electricity, while natural photosystems based solar‐powered energy‐storage device is still under developed. Here, we fabricate a new kind of photo‐rechargeable zinc‐ion hybrid capacitor (ZHC) benefiting from light‐harvesting carbon dots (CDs) and natural thylakoids for realizing solar energy harvesting and storage simultaneously. Under solar light irradiation, the embedded CDs in thylakoids (CDs/Thy) can convert the less absorbed green light into highly absorbed red light for thylakoids, besides, Förster resonance energy transfer (FRET) between CDs and Thy also occurs, which facilitates the photoelectrons generation during thylakoids photosynthesis, thereby resulting in 6‐fold photocurrent output in CDs/Thy hybrid photosystem, compared to pristine thylakoids. Using CDs/Thy as the photocathode in ZHCs, the photonic hybrid capacitor shows photoelectric conversion and storage features. CDs can improve the photo‐charging voltage response of ZHCs to ≈1.2 V with a remarkable capacitance enhancement of 144 % under solar light. This study provides a promising strategy for designing plant‐based photonic and electric device for solar energy harvesting and storage. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs)—carbon nanoparticles smaller than 10 nm—have attracted widespread attention owing to their excellent optical properties. However, high‐performing CDs often suffer from severe aggregation‐induced quenching in the solid state, which limits their commercial applicability. Therefore, CD materials with efficient solid‐state luminescence are sought. As research on the structure and photoluminescence mechanisms of CDs has intensified in recent years, strategies to construct fluorescent solid‐state CD materials and tune their emissions have broadened. This article reviews recent advances in the strategies and mechanisms for attaining solid‐state fluorescence in CDs, describes specific ways to tune the optical properties of this fluorescence, introduces the latest applications of the resulting CDs to optoelectronics, biology, and sensing, and finally considers the prospects for future application and current challenges facing the development of solid‐state fluorescence in CDs. [ABSTRACT FROM AUTHOR]