Direct Solvent‐Derived Polymer‐Coated Nitrogen‐Doped Carbon Nanodots with High Water Solubility for Targeted Fluorescence Imaging of Glioma

Cancer imaging requires biocompatible and bright contrast‐agents with selective and high accumulation in the tumor region but low uptake in normal tissues. Herein, 1‐methyl‐2‐pyrrolidinone (NMP)‐derived polymer‐coated nitrogen‐doped carbon nanodots (pN‐CNDs) with a particle size in the range of 5–15 nm are prepared by a facile direct solvothermal reaction. The as‐prepared pN‐CNDs exhibit stable and adjustable fluorescence and excellent water solubility. Results of a cell viability test (CCK‐8) and histology analysis both demonstrate that the pN‐CNDs have no obvious cytotoxicity. Most importantly, the pN‐CNDs can expediently enter glioma cells in vitro and also mediate glioma fluorescence imaging in vivo with good contrast via elevated passive targeting.     

Long‐Range Nanoparticle Surface‐Energy‐Transfer Ruler for Monitoring Photothermal Therapy Response

A recent gold nanotechnology‐driven approach opens up a new possibility for the destruction of cancer cells through photothermal therapy. Ultimately, photothermal therapy may enter into clinical therapy and, as a result, there is an urgent need for techniques to monitor the tumor response to therapy. Driven by this need, a nanoparticle surface‐energy‐transfer (NSET) approach to monitor the photothermal therapy process by measuring a simple fluorescence intensity change is reported. The fluorescence intensity change is due to the light‐controlled photothermal release of single‐stranded DNA/RNA via dehybridization during the therapy process. Time‐dependent results show that just by measuring the fluorescence intensity change, the photothermal therapy response during the therapy process can be monitored. The possible mechanism and operating principle of the NSET assay are discussed. Ultimately, this NSET assay could have enormous potential applications in rapid, on‐site monitoring of the photothermal therapy process, which is critical to providing effective treatment of cancer and multidrug‐resistant bacterial infections.     

Retrosynthesis of Tunable Fluorescent Carbon Dots for Precise Long‐Term Mitochondrial Tracking

Mitochondria play a significant role in many cellular processes. Precise long‐term tracking of mitochondrial status and behavior is very important for regulating cell fate and treating mitochondrial diseases. However, developing probes with photostability, long‐term tracking capability, and tunable long‐wavelength fluorescence has been a challenge in mitochondrial targeting. Carbon dots (CDs) as new fluorescent nanomaterials with low toxicity and high stability show increasing advantages in bioimaging. Herein, the mitochondria tracking CDs (MitoTCD) with intrinsic mitochondrial imaging capability and tunable long‐wavelength fluorescence from green to red are synthesized where the lipophilic cation of rhodamine is served as the luminescent center of CDs. Due to the excellent photostability, superior fluorescence properties and favorable biocompatibility, these MitoTCD are successfully used for mitochondrial targeting imaging of HeLa cells in vitro and can be tracked as long as six passages, which is suitable for long‐term cell imaging. Moreover, these MitoTCD can also be used for zebrafish imaging in vivo.     

Crosslinked Carbon Dots as Ultra‐Bright Fluorescence Probes

Carbon dots (surface‐passivated small carbon nanoparticles) are crosslinked to result in fluorescence probes containing one or multiple dots. For the single‐dot probes, the crosslinking further stabilizes the dot structure, while for those packed with multiple dots, the individual probe imaging results demonstrate that the fluorescence properties are additive, with more dots for higher emission intensities in a proportional fashion, thus enabling the preparation of ultra‐bright fluorescence probes.     

Understanding and Manipulating the Interplay of Wide‐Energy‐Gap Host and TADF Sensitizer in High‐Performance Fluorescence OLEDs

Comprising an emitting layer (EML) constituting a wide‐energy‐gap host, a thermally activated delayed fluorescence (TADF) sensitizer and a conventional fluorescent dopant, TADF‐sensitizing‐fluorescence organic light‐emitting diodes (TSF‐OLEDs) highly depend on component interplay to maximize their performance, which, however, is still under‐researched. Taking the host type (TADF or non‐TADF) and the recombination position (on the host or on the TADF sensitizer) into consideration, the interplay of host and TADF sensitizer is comprehensively studied and manipulated. A wide‐energy‐gap host with TADF and recombination of charges on it are both required to maximize device performances by triggering multiple sensitizing processes to eliminate exciton losses. Based on those findings, a maximum external quantum efficiency (EQE)/power efficiency (PE) of 23.2%/76.9 lm W^?1 is realized with a newly developed TADF host, significantly outperforming the reference devices. Further device optimization leads to unprecedently high EQE/PE of 24.2%/89.5 lm W^?1 and a half‐lifetime of over 400 h at an initial luminance of 2000 cd m^?2, with the peak PE being the highest value among the reported TSF‐OLEDs. This work reveals the importance of manipulating the component interplay in EMLs, opening a new avenue toward highly efficient TSF‐OLEDs.     

Tunable Luminescent Carbon Nanospheres with Well‐Defined Nanoscale Chemistry for Synchronized Imaging and Therapy

In this work, we demonstrate the significance of defined surface chemistry in synthesizing luminescent carbon nanomaterials (LCN) with the capability to perform dual functions (i.e., diagnostic imaging and therapy). The surface chemistry of LCN has been tailored to achieve two different varieties: one that has a thermoresponsive polymer and aids in the controlled delivery of drugs, and the other that has fluorescence emission both in the visible and near‐infrared (NIR) region and can be explored for advanced diagnostic modes. Although these particles are synthesized using simple, yet scalable hydrothermal methods, they exhibit remarkable stability, photoluminescence and biocompatibility. The photoluminescence properties of these materials are tunable through careful choice of surface‐passivating agents and can be exploited for both visible and NIR imaging. Here the synthetic strategy demonstrates the possibility to incorporate a potent antimetastatic agent for inhibiting melanomas in vitro. Since both particles are Raman active, their dispersion on skin surface is reported with Raman imaging and utilizing photoluminescence, their depth penetration is analysed using fluorescence 3D imaging. Our results indicate a new generation of tunable carbon‐based probes for diagnosis, therapy or both.     

Chirality‐Selective Photoluminescence Enhancement of ssDNA‐Wrapped Single‐Walled Carbon Nanotubes Modified with Gold Nanoparticles

In this work, a convenient method to enhance the photoluminescence (PL) of single‐walled carbon nanotubes (SWNTs) in aqueous solutions is provided. Dispersing by single‐stranded DNA (ssDNA) and modifying with gold nanoparticles (AuNPs), about tenfold PL enhancement of the SWNTs is observed. More importantly, the selective PL enhancement is achieved for some particular chiralities of interest over all other chiralities, by using certain specific ssDNA sequences that are reported to recognize these particular chiralities. By forming AuNP–DNA–SWNT nanohybrids, ssDNA serves as superior molecular spacers that on one hand protect SWNT from direct contacting with AuNP and causing PL quench, and on the other hand attract the AuNP in close proximity to the SWNT to enhance its PL. This PL enhancement method can be utilized for the PL analysis of SWNTs in aqueous solutions, for biomedical imaging, and may serve as a prescreening method for the recognition and separation of single chirality SWNTs by ssDNA.     

In vivo Metabolic Imaging of Insulin with Multiphoton Fluorescence of Human Insulin–Au Nanodots

Functional human insulin–Au nanodots (NDs) are synthesized for the in vivo imaging of insulin metabolism. Benefiting from its efficient red to near infrared fluorescence, deep tissue subcellular uptake of insulin–Au NDs can be clearly resolved through a least‐invasive harmonic generation and two‐photon fluorescence (TPF) microscope. In vivo investigations on mice ear and ex vivo assays on human fat tissues conclude that cells with rich insulin receptors have higher uptake of administrated insulin. Interestingly, the insulin–Au NDs can even permeate into lipid droplets (LDs) of adipocytes. Using this newly discovered metabolic phenomenon of insulin, it is found that enlarged adipocytes in type II diabetes mice have higher adjacent/LD concentration contrast with small‐sized ones in wild type mice. For human clinical samples, the epicardial adipocytes of patients with diabetes and coronary artery disease (CAD) also show elevated adjacent/LD concentration contrast. As a result, human insulin–Au nanodots provide a new approach to explore subcellular insulin metabolism in model animals or patients with metabolic or cardiovascular diseases.     

Tumor‐Targeting Multifunctional Rattle‐Type Theranostic Nanoparticles for MRI/NIRF Bimodal Imaging and Delivery of Hydrophobic Drugs

The development of theranostic systems capable of diagnosis, therapy, and target specificity is considerably significant for accomplishing personalized medicine. Here, a multifunctional rattle‐type nanoparticle (MRTN) as an effective biological bimodal imaging and tumor‐targeting delivery system is fabricated, and an enhanced loading ability of hydrophobic anticancer drug (paclitaxel) is also realized. The rattle structure with hydrophobic Fe₃O₄ as the inner core and mesoporous silica as the shell is obtained by one‐step templates removal process, and the size of interstitial hollow space can be easily adjusted. The Fe₃O₄ core with hydrophobic poly(tert‐butyl acrylate) (PTBA) chains on the surface is not only used as a magnetic resonance imaging (MRI) agent, but contributes to improving hydrophobic drug loading amount. Transferrin (Tf) and a near‐infrared fluorescent dye (Cy 7) are successfully modified on the surface of the nanorattle to increase the ability of near‐infrared fluorescence (NIRF) imaging and tumor‐targeting specificity. In vivo studies show the selective accumulation of MRTN in tumor tissues by Tf‐receptor‐mediated endocytosis. More importantly, paclitaxel‐loaded MRTN shows sustained release character and higher cytotoxicity than the free paclitaxel. This theranostic nanoparticle as an effective MRI/NIRF bimodal imaging probe and drug delivery system shows great potential in cancer diagnosis and therapy.     

One‐Step Synthesis of Silica‐Coated Carbon Dots with Controllable Solid‐State Fluorescence for White Light‐Emitting Diodes

Carbon dots (CDots)‐based solid‐state luminescent materials have important applications in light‐emitting devices owing to their outstanding optical properties. However, it still remains a challenge to develop multiple‐color‐emissive solid‐state CDots, due to the serious self‐quenching of the CDots in the aggregation or solid state. Herein, a one‐step synthesis of multiple‐color‐emissive solid‐state silica‐coated CDots (silica/CDots) composites by controlling CDots loading fraction and composite morphology to realize the adjustment of emitting color is reported. The emission of resultant silica/CDots composites shifts from blue to orange with the photoluminescence quantum yields of 57.9%, 34.3%, and 32.7% for blue, yellow, and orange emitting, respectively. Furthermore, the yellow emitting silica/CDots composites exhibit an excellent fluorescence thermal stability, and further have been applied to fabricate white‐light‐emitting devices with a high color rendering index of above 80.