Construction of graphene quantum dots ratiometric fluorescent probe by intermolecular electron transfer effect for intelligent and real-time visual detection of ofloxacin and its L-isomer in daily drink.

The design of intelligent and real-time sensing devices is significant in the medical drug monitoring field, but it is still highly challenging. Here, ratiometric fluorescent detections of ofloxacin (OFL) and its L-isomer levofloxacin (LEV) constructed from tri-doped graphene quantum dots (T-GQDs) are reported, and the detection limits reach as low as 46/67 nM toward OFL/LEV due to the intermolecular electron transfer (intermolecular ET) effect. After adding OFL/LEV, the generation of electrostatic bond provides a channel for the intermolecular ET from the edge of T-GQDs to OFL/LEV, resulting in the fluorescence quenching at 414 nm and the fluorescence promoting at 498 nm. Furthermore, a smartphone can be used for the visual and quantitative detection of OFL and LEV by identifying the RGB values of test paper and drink samples. This work not only reveals the physics mechanism of ratiometric detection, but also develops a convenient smartphone diagnostic for OFL and LEV.

Promising energy transfer system between fuorine and nitrogen Co-doped graphene quantum dots and Rhodamine B for ratiometric and visual detection of doxycycline in food.

A novel sensor based on dual emissive fluorescent graphene quantum dots is developed for a rapid, selective, sensitive and visual detection of doxycycline (DOX). The ratiometric fluorescent probe is designed by grafting fluorescent group (Rhodamine B, RhB) on F, N-doped graphene quantum dots (FNGQDs). In the presence of DOX, the fluorescence at 466 nm is remarkably quenched due to inner filter effect and fluorescence resonance energy transfer, whereas the peak at 592 nm is attenuated slightly due to the energy transfer in the emission peaks of FNGQDs and RhB functional group. The sensor shows good linear relationship from 0.04 to 100 µM with a low detection limit of 40 nM. Furthermore, the flexible solid-state fluorescent sensing platform is used for detecting DOX in milk, pork and water samples. Therefore, this dual-emission FGQD-RhB can be used as a high-performance fluorescent and visual sensor for food safety and environmental monitoring.

Mechanisms behind multicolor tunable Near-Infrared triple emission in graphene quantum dots and ratio fluorescent probe for water detection.

Developing environmental-friendly and low-cost strategies of synthesizing red-emission graphene quantum dots (R-GQDs) is a considerable challenge. Herein, we present the green and facile preparation of R-GQDs by using o-phenylenediamine (o-PD) and catechol as precursors via oxidation/polymerization and Schiff base reaction at low temperature (80 °C) for 3 hrs. Results show that the prepared R-GQDs exhibit triple fluorescence emissions, which is enabled by the introduce of different nitrogen (pyrrolic N, pyridinic N, and amino N) species on the surface of R-GQDs. Moreover, the R-GQDs are implemented to detect the moisture in different organic solvent. A highly sensitive ratiometric sensing of water in organic solvents is achieved, and the relationship between the change of fluorescence signal caused by moisture and the corresponding internal emission site is also determined. In the end, the multicolor light emissions of R-GQDs are realized by simply adjusting the polarity of surrounding solvents. And based on the solvatochromism of R-GQDs, the multicolor solid fluorescent powder and ink are prepared for illumination application. All in all, the above research work presents a novel R-GQDs for wide application in detecting and illumination.

A smartphone-integrated optical sensing platform based on Lycium ruthenicum derived carbon dots for real-time detection of Ag.

Growing global environmental pollution problems challenge the need for converting biomass into an advantageous product. In this paper, Lycium ruthenicum is successfully turned into beneficial green emissive (527 nm) fluorescent nitrogen doping carbon dots (N-CDs) via the hydrothermal treatment for the first time. The horizontal and vertical dimensions of N-CDs are demonstrated to be about 4.5 and 0.73 nm, respectively. The N-CDs possess an extremely stable green fluorescence and quantum yield up to 21.8%. Meaningfully, N-CDs exhibit a good linear relationship with Ag+ in the range of 0.7-36 µM, and its detection limit is determined to be 59 nM. The practicability of the fluorescent probe is further validated in lake water and the satisfactory spiked recoveries of Ag+ ranges from 98.99% to 104.19%. Besides, based on the sensitive and selective photoluminescence quenching properties, a smartphone-based laboratory device and RGB analysis software are used to directly capture and analyze fluorescence images with a sensitive detection limit of 83 nM for Ag+. This novel sensor based on N-CDs and smartphone provides a reliable way for on-site monitoring of Ag+ and expands application prospect in the field of environmental pollution detection.

PVDF-triggered multicolor fluorine-doped graphene quantum dots for water detection and anti-counterfeiting.

Fluorescent fluorine-doped graphene quantum dots (F-GQDs) have been synthesized via the hydrothermal method using long-chain polymer polyvinylidene fluoride (PVDF) as the precursor. Due to the unique molecular structure of PVDF, a possible synthesis process of F-GQDs has been put forward. F-GQDs have adjustable emission wavelength by simply adjusting the concentration of the solution. As the concentration increases, the emission wavelength of F-GQDs gradually red shifts from 455 nm (blue) to 551 nm (yellow-green). In addition, F-GQDs also exhibit a sensitive fluorescence response to water content in organic solvents, and the ultralow detections limit are 0.056% in ethanol and 0.124% in DMF. Besides, due to strong UV absorption capacity, a photothermal film is fabricated by embedding F-GQDs in PDMS. The temperature of F-GQDs/PDMS polymer film can reach 33.4 oC under simulated sunlight, while the maximum temperature of blank PDMS film only reach 29.4 oC. Based on this phenomenon, a new type of anti-counterfeiting device is designed by combining F-GQDs/PDMS film with temperature change ink.

Synthesis of multi-color fluorine and nitrogen co-doped graphene quantum dots for use in tetracycline detection, colorful solid fluorescent ink, and film.

Fluorine-doped graphene quantum dots have unique chemical bonds and charge distribution, which can bring unexpected properties compared to other common atom-doped graphene quantum dots. In the present work, fluorine and nitrogen co-doped graphene quantum dots (F, N-GQDs) are synthesized from levofloxacin via a simple hydrothermal method. Systematic studies demonstrate that F, N-GQDs can emit various fluorescence with the wavelength ranging from blue to green by dispersing F, N-GQDs into different solvents. Moreover, multi-color fluorescence is available by simply changing the concentration of F, N-GQDs. In addition to these unique characteristics, F, N-GQDs also exhibit a sensitive fluorescence response to tetracycline with an ultralow detection limit of 77 nM in water. Because of high photostability and high quantum yield, the F, N-GQDs are exploited as a unique invisible ink, which is printable and writable on paper. Meanwhile, based on the solvatochromism of F, N-GQDs, we realized the color adjustable fluorescent ink. Finally, large-area flexible multi-color fluorescent films are realized. Our synthesized F, N-GQDs, with tunable fluorescence in wavelength and intensity, have numerous opportunities for optical molecular sensors, information security, flexible optics, and others.

Serum LUCAT1 implicates the pathogenesis of muscle-invasive bladder cancer via targeting miR-199a-5p and miR-199b-5p.

Muscle-invasive bladder cancer (MIBC) is a common malignancy of urinary system cancers, accounting for about 1/3 of all newly diagnosed bladder cancer cases. Due to its strong metastasis, the 5-year survival of MIBC is less than 50%, and in serious cases, the overall survival of metastatic bladder cancer patients is about 1.3 years. LncRNAs, a type of non-coding RNAs defined as the transcripts exceeding 200 nucleotides in length, are frequently aberrant in multiple cancers including cervical, ovarian, breast and bladder cancers. Recently, LUCAT1 (short for lung cancer-associated transcript 1), a lncRNA first reported to be involved in smoking-related lung cancer, has been observed to exhibit crucial roles in the epithelial-to-mesenchymal transition (EMT), migration and invasion processes of clear cell renal cell carcinoma (ccRCC) and colorectal cancer. However, whether it involves in the pathogenesis of MIBC remains underexplored. In the present study, LUCAT1 was up-regulated in the serum samples of MIBC patients and bladder cancer cell lines, as assessed using real-time PCR. Our in vitro data (including wound healing and trans-well assays) showed that LUCAT1 was required for the proliferation, EMT, migration and invasion processes of T24 cells. Moreover, LUCAT1 directly targeted miR-199a-5p and miR-199b-5p, as affirmed using the luciferase reporter assay, and manipulation of LUCAT1 significantly suppressed miR-199a-5p and miR-199b-5p. Collectively, our findings highlight an axis of LUCAT1/miR-199a/b-5p in MIBC pathogenesis. Therefore, LUCAT1 may possibly be a promising candidate for diagnostic biomarker and therapeutic target of MIBC.