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Journal ArticleDOI

Ultrasensitive Fluorometric Angling Determination of Staphylococcus aureus in Vitro and Fluorescence Imaging in Vivo Using Carbon Dots with Full-Color Emission

TL;DR: An ultrasensitive magnetic fluorescence aptasensor was designed for separation and detection of Staphylococcus aureus and exhibited excellent biocompatibility and was applied as fluorescent probes for bioimaging both in vitro and in vivo.
Abstract: Rapid, accurate, and safe screening of foodborne pathogenic bacteria is essential to effectively control and prevent outbreaks of foodborne illness. Fluorescent sensors constructed from carbon dots (CDs) and nanomaterial-based quenchers have provided an innovative method for screening of pathogenic bacteria. Herein, an ultrasensitive magnetic fluorescence aptasensor was designed for separation and detection of Staphylococcus aureus (S. aureus). Multicolor fluorescent CDs with a long fluorescent lifetime (6.73 ns) and high fluorescence stability were synthesized using a facile hydrothermal approach and modified cDNA as a highly sensitive fluorescent probe. CD fluorescence was quenched by Fe3O4 + aptamer via fluorescence resonance energy transfer (FRET). Under optimal conditions, the FRET-based aptasensor can detect S. aureus accompanied by a wide linear range of 50-107 CFU·mL-1 and a detection limit of 8 CFU·mL-1. Compared with other standard methods, this method was faster and more convenient, and the entire test was finished within 30 min. The capability of the aptasensor was simultaneously investigated on food samples. Additionally, the developed CDs exhibited excellent biocompatibility and were thus applied as fluorescent probes for bioimaging both in vitro and in vivo. This new platform provided an excellent application of the CDs for detecting and bioimaging pathogenic bacteria.
Citations
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Journal ArticleDOI
TL;DR: This review provides concise insights into the recent development of CDs in nanomedicine research, including preparation and functionalization processes, and a few critical applications are highlighted, such as antibacterial applications, chemotherapy, and therapeutics.

119 citations

Journal ArticleDOI
TL;DR: In this paper, an electrochemical detector of a functional two-dimensional (2D) metal-organic framework (MOF) nanozyme was developed for the sensitive detection of pathogenic Staphylococcus aureus.
Abstract: Bacterial infection is one of the major causes of human death worldwide. To prevent bacterial infectious diseases from spreading, it is of critical importance to develop convenient, ultrasensitive, and cost-efficient methods for bacteria detection. Here, an electrochemical detector of a functional two-dimensional (2D) metal-organic framework (MOF) nanozyme was developed for the sensitive detection of pathogenic Staphylococcus aureus. A dual recognition strategy consisting of vancomycin and anti-S. aureus antibody was proposed to specifically anchor S. aureus. The 2D MOFs with excellent peroxidase-like activity can efficiently catalyze o-phenylenediamine to 2,2-diaminoazobenzene, which is an ideal electrochemical signal readout for monitoring the bacteria concentration. Under optimal conditions, the present bioassay provides a wide detection range of 10-7.5 × 107 colony-forming units CFU/mL with a detection limit of 6 CFU/mL, which is better than most of the previous reports. In addition, the established electrochemical sensor can selectively and accurately identify S. aureus in the presence of other bacteria. The present work provides a new pathway for sensitive and selective detection of S. aureus and presents a promising potential in the realm of clinical diagnosis.

69 citations

Journal ArticleDOI
TL;DR: A promising potential of integrating the concepts of remarkable large Stokes shift and dual-recognition into a single matrix for developing pathogenic microorganism stimuli-responsive ratiometric nanoprobe with speediness, cost-efficiency, stability, ultrahigh specificity and sensitivity is reported.
Abstract: Rapid, accurate, reliable, and risk-free tracking of pathogenic microorganisms at the single-cell level is critical to achieve efficient source control and prevent outbreaks of microbial infectious diseases. For the first time, we report a promising approach for integrating the concepts of a remarkably large Stokes shift and dual-recognition into a single matrix to develop a pathogenic microorganism stimuli-responsive ratiometric fluorescent nanoprobe with speed, cost efficiency, stability, ultrahigh specificity, and sensitivity. As a proof-of-concept, we selected the Gram-positive bacterium Staphylococcus aureus (S. aureus) as the target analyte model, which easily bound to its recognition aptamer and the broad-spectrum glycopeptide antibiotic vancomycin (Van). To improve the specificity and short sample-to-answer time, we employed classic noncovalent π-π stacking interactions as a driving force to trigger the binding of Van and aptamer dual-functionalized near-infrared (NIR) fluorescent Apt-Van-QDs to the surface of an unreported blue fluorescent π-rich electronic carbon nanoparticles (CNPs), achieving S. aureus stimuli-responsive ratiometric nanoprobe Apt-Van-QDs@CNPs. In the assembly of Apt-Van-QDs@CNPs, the blue CNPs (energy donor) and NIR Apt-Van-QDs (energy acceptor) became close to allow the fluorescence resonance energy transfer (FRET) process, leading to a remarkable blue fluorescence quenching for the CNPs at ∼465 nm and a clear NIR fluorescence enhancement for Apt-Van-QDs at ∼725 nm. In the presence of S. aureus, the FRET process from CNPs to Apt-Van-QDs was disrupted, causing the nanoprobe Apt-Van-QDs@CNPs to display a ratiometric fluorescent response to S. aureus, which exhibited a large Stokes shift of ∼260 nm and rapid sample-to-answer detection time (∼30.0 min). As expected, the nanoprobe Apt-Van-QDs@CNPs showed an ultrahigh specificity for ratiometric fluorescence detection of S. aureus with a good detection limit of 1.0 CFU/mL, allowing the assay at single-cell level. Moreover, we also carried out the precise analysis of S. aureus in actual samples with acceptable results. We believe that this work offers new insight into the rational design of efficient ratiometric nanoprobes for rapid on-site accurate screening of pathogenic microorganisms at the single-cell level in the early stages, especially during the worldwide spread of COVID-19 today.

58 citations

Journal ArticleDOI
TL;DR: A fluorescent antibacterial hydrogel with antibacterial ability, excellent optical performance, and high biocompatibility was developed based on cationic carbon dots (CDs), pectin, and acrylic acid triggered construction of the hydrogels network by cross-linker.

45 citations

Journal ArticleDOI
Zhonghui Sun1, Fanyong Yan1, Jing Xu1, Hao Zhang1, Li Chen1 
TL;DR: In this article, the authors used citric acid (CA) and Nile Blue A (NBA) as precursors to obtain bright blue, yellow and red fluorescence emission CDs (B-, Y-and RCDs).
Abstract: Carbon dots (CDs), as a new kind of carbon-based luminescent nanomaterials, have drawn widespread attention in the fields of fluorescence sensing, optoelectronic devices, and biological imaging. This work uses citric acid (CA) and Nile Blue A (NBA) as precursors. By simply changing the solvent in the reaction, their bandgaps were systematically controlled, thereby successfully obtaining bright blue, yellow and red fluorescence emission CDs (B-, Y- and RCDs). The higher quantum yield (QY) of B-, Y- and RCDs are 64%, 57% and 51%, respectively. The selected precursors and different solvents are the key to the formation of three emission CDs. Detailed characterization and density functional theory (DFT) calculations further indicate that the difference in emission color of CDs is due to the size of the sp2 conjugate domain. In addition, we used multicolor CDs as fluorescent probes to investigate their performance in detection. Among them, BCDs and YCDs can detect Sudan Red I with high selectivity and sensitivity. In the concentration range of 0 to 80 µM, the detection limits are 56 and 41 nM, respectively. Multicolor emitting phosphors and fluorescent films are also obtained by mixing CDs with other matrices. Using Ultraviolet (UV) chip as the excitation source and combining with multicolor fluorescent film and a certain proportion of B-, Y-, and RCDs/epoxy resin composites, bright monochromatic light-emitting diodes (LEDs) and white LED (WLED) with high color rendering index (CRI) were prepared. The above results indicate that the multicolor CDs prepared by us have great application potential in the fields of food safety control and optical devices.

42 citations

References
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Journal ArticleDOI
TL;DR: A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission and FLQY = fluorescence quantum yield.
Abstract: Helpful elements: A facile bottom-up method using citric acid and L-cysteine as a precursor has been developed to prepare graphene quantum dots (GQDs) co-doped with nitrogen and sulfur. A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission. FLQY = fluorescence quantum yield.

1,887 citations

Journal ArticleDOI
26 Jan 2016-ACS Nano
TL;DR: Carbon dots with tunable photoluminescence (PL) and a quantum yield of up to 35% in water were hydrothermally synthesized in one pot and separated via silica column chromatography, and these separated CDs emitted bright and stable luminescence in gradient colors under a single-wavelength UV light.
Abstract: Carbon dots (CDs) with tunable photoluminescence (PL) and a quantum yield of up to 35% in water were hydrothermally synthesized in one pot and separated via silica column chromatography. These separated CDs emitted bright and stable luminescence in gradient colors from blue to red under a single-wavelength UV light. They exhibited high optical uniformity; that is, every sample showed only one peak in the PL excitation spectrum, only one peak in the excitation-independent PL emission spectrum, and similar monoexponential fluorescence lifetimes. Although these samples had similar distributions of particle size and graphite structure in their carbon cores, the surface state gradually varied among the samples, especially the degree of oxidation. Therefore, the observed red shift in their emission peaks from 440 to 625 nm was ascribed to a gradual reduction in their band gaps with the increasing incorporation of oxygen species into their surface structures. These energy bands were found to depend on the surfac...

1,707 citations

Journal ArticleDOI
01 Apr 2015-Small
TL;DR: The properties and synthesis methods of these carbon nanodots are reviewed and emphasis is placed on their biological (both fundamental and theranostic) applications.
Abstract: The emerging graphene quantum dots (GQDs) and carbon dots (C-dots) have gained tremendous attention for their enormous potentials for biomedical applications, owing to their unique and tunable photoluminescence properties, exceptional physicochemical properties, high photostability, biocompatibility, and small size. This article aims to update the latest results in this rapidly evolving field and to provide critical insights to inspire more exciting developments. We comparatively review the properties and synthesis methods of these carbon nanodots and place emphasis on their biological (both fundamental and theranostic) applications.

1,665 citations

Journal ArticleDOI
TL;DR: The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light-emitting diodes, full-color displays, and multiplexed (UC)PL bioimaging.
Abstract: A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet-light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up-conversion (UC)PL of these CDs is also observed. Moreover, flexible full-color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light-emitting diodes, full-color displays, and multiplexed (UC)PL bioimaging.

1,504 citations

Journal ArticleDOI
TL;DR: MRSA should be a national priority for disease control, according to the World Health Organization.
Abstract: Hospital-acquired infections with Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) infections, are a major cause of illness and death and impose serious economic costs on patients and hospitals. However, the recent magnitude and trend of these infections have not been reported. We used national hospitalization and resistance data to estimate the annual number of hospitalizations and deaths associated with S. aureus and MRSA from 1999 through 2005. During this period, the estimated number of S. aureus-related hospitalizations increased 62%, from 294,570 to 477,927, and the estimated number of MRSA-related hospitalizations more than doubled, from 127,036 to 278,203. Our findings suggest that S. aureus and MRSA should be considered a national priority for disease control.

925 citations