Carbon Dots for Bacterial Detection and Antibacterial Applications-A Minireview

2020 ◽  
Vol 25 (46) ◽  
pp. 4848-4860 ◽  
Author(s):  
Anisha Anand ◽  
Gopinathan Manavalan ◽  
Ranju Prasad Mandal ◽  
Huan-Tsung Chang ◽  
Yi-Ru Chiou ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Antibacterial Effect ◽  
Bacterial Detection ◽  
High Brightness ◽  
Photo Catalysis ◽  
Wide Range ◽  
Prevention And Treatment ◽  
Low Toxicity ◽  
Conventional Antibiotics

: The prevention and treatment of various infections caused by microbes through antibiotics are becoming less effective due to antimicrobial resistance. Researches are focused on antimicrobial nanomaterials to inhibit bacterial growth and destroy the cells, to replace conventional antibiotics. Recently, carbon dots (C-Dots) become attractive candidates for a wide range of applications, including the detection and treatment of pathogens. In addition to low toxicity, ease of synthesis and functionalization, and high biocompatibility, C-Dots show excellent optical properties such as multi-emission, high brightness, and photostability. C-Dots have shown great potential in various fields, such as biosensing, nanomedicine, photo-catalysis, and bioimaging. This review focuses on the origin and synthesis of various C-Dots with special emphasis on bacterial detection, the antibacterial effect of CDots, and their mechanism.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

scholarly journals Carbon Dots: Synthesis, Properties and Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3419
Author(s):  
Lin Cui ◽  
Xin Ren ◽  
Mengtao Sun ◽  
Haiyan Liu ◽  
Lixin Xia
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Research Field ◽  
Potential Development ◽  
Synthesis Properties ◽  
Photo Induced Electron Transfer ◽  
Low Toxicity ◽  
Synthesis Routes ◽  
Carbon Based Nanomaterials ◽  
Photocatalytic Applications

Carbon dots (CDs) are known as the rising star of carbon-based nanomaterials and, by virtue of their unique structure and fascinating properties, they have attracted considerable interest in different fields such as biological sensing, drug delivery, photodynamic therapy, photocatalysis, and solar cells in recent years. Particularly, the outstanding electronic and optical properties of the CDs have attracted increasing attention in biomedical and photocatalytic applications owing to their low toxicity, biocompatibility, excellent photostability, tunable fluorescence, outstanding efficient up-converted photoluminescence behavior, and photo-induced electron transfer ability. This article reviews recent progress on the synthesis routes and optical properties of CDs as well as biomedical and photocatalytic applications. Furthermore, we discuss an outlook on future and potential development of the CDs based biosensor, biological dye, biological vehicle, and photocatalysts in this booming research field.

scholarly journals Microwave Assisted Synthesis and Optical Properties of Highly Fluorescent N-Doped Carbon Dots

2019 ◽  
Vol 31 (12) ◽  
pp. 2897-2902
Author(s):  
D. Koteswararao ◽  
B. Rajkumar ◽  
K. Prameela ◽  
K. Ashok ◽  
G. Sridevi
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Irradiation Time ◽  
Guanidine Hydrochloride ◽  
Fluorescence Emission ◽  
Microwave Assisted Synthesis ◽  
Solid State Method ◽  
Microwave Assisted ◽  
Wide Range ◽  
Doped Carbon Dots

Herein, a rapid microwave assisted solid state method is reported for the synthesis of highly fluorescent N-doped carbon dots (NCDs) using citric acid as carbon source and guanidine hydrochloride as N-dopant. Synthetic parameters such as microwave power, irradiation time and reactants ratio were optimized to produce high quality N-doped carbon dots. The N-doped carbon dots were well characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), SEM-EDS, FTIR, UV-visible and fluorescence spectroscopies. N-Doped carbon dots exhibited bright emission with a quantum yield of 11 %. Detailed study of their optical properties revealed their excellent property of resistance to photo bleaching, high ionic strength and solution pH. Further they exhibited excitation dependent emission behaviour, high aqueous solubility and a long shelf life of 60 days. This strong fluorescence emission combined with high stability make N-doped carbon dots a promising fluorescent probe for wide range of applications.

scholarly journals Fluorescent carbon dots with excellent moisture retention capability for moisturizing lipstick

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Chen Dong ◽  
Mingsheng Xu ◽  
Shuna Wang ◽  
Menghui Ma ◽  
Ozioma U. Akakuru ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Chemical Processes ◽  
Moisture Retention ◽  
Low Toxicity ◽  
Nano Additives ◽  
First Time ◽  
The Relationship ◽  
Fluorescent Carbon Dots ◽  
Huge Challenge

AbstractLong-lasting moisture retention is a huge challenge to humectants, and effective methods or additives for promote these functions are limited, especially nano-additives. Carbon dots (CDs) have attracted increasing research interest due to its ultra-small size, excellent optical properties and low toxicity, etc. However, most of researches have been focused on the photoexcited CDs and its subsequent photophysical and chemical processes, such as photoluminescence, photodynamic, photothermal and photocatalytic behavior. The intrinsic chemo-physical properties of the pristine CDs are not fully explored. Here, we report an excellent moisture retention capability of a new carmine cochineal-derived CDs (Car-CDs) for the first time. The relationship between the structure of Car-CDs and its moisture retention capability is revealed. More interestingly, the effective applications of Car-CDs in moisturizing lipstick are demonstrated. This work expands the research and application of CDs into a broad, new area, potentially in skin care.

scholarly journals Fluorescent Carbon Nanodots as Sensors of Toxic Metal Ions and Pesticides

2021 ◽  
Vol 6 (1) ◽  
pp. 21
Author(s):  
Federico Bruno ◽  
Alice Sciortino ◽  
Gianpiero Buscarino ◽  
Marco Cannas ◽  
Franco Mario Gelardi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Low Cost ◽  
Synthesis Method ◽  
Toxic Metal ◽  
Size Exclusion ◽  
Carbon Nanodots ◽  
Molar Ratios ◽  
Wide Range ◽  
Fluorescent Carbon

Carbon nanodots (CDs) are a new class of fluorescent carbon-based nanomaterials characterized by a plethora of morphologies and sizes. Among these, we can include two different types of CDs, namely, graphitic and diamond-like. This wide range of structures opens up the possibility to design different CDs, with tunable optical properties accordingly to the synthesis method and precursors used. We prepared two different CDs following a bottom-up approach by thermally induced decomposition of organic precursors (namely, citric acid and urea in different molar ratios), and using purification by Size Exclusion Chromatography (SEC). Obtained CDs were characterized by Raman, absorption and fluorescence (PL) spectroscopies to understand structural and optical properties, and by atomic force microscopy (AFM) to elucidate morphology. They feature graphitic and diamond-like carbon structures with highly efficient visible emissions. Their sensing towards Cd and Hg heavy metals has been tested by PL experiments. We found a PL quenching in the presence of concentrations of metal salts starting from 0.5 μM and a selectivity towards the interacting ions, depending on the CDs structure, enabling using them for sensing. Furthermore, preliminary experiments suggest that these dots can also be used in principle as sensors of common pesticides. Considering the advantages of carbon dots with respect to other nanomaterials, such as non-toxicity, low cost and ease of synthesis, we consider these results to be very promising in view of exploiting the optical response of carbon dots to fabricate in the near future a variety of pollutant-sensing devices.

scholarly journals Synthesis of Fluorescent Carbon Dots as Selective and Sensitive Probes for Cupric Ions and Cell Imaging

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1785 ◽  
Author(s):  
Shu-Wei Huang ◽  
Yu-Feng Lin ◽  
Yu-Xuan Li ◽  
Cho-Chun Hu ◽  
Tai-Chia Chiu
Keyword(s):  
Carbon Dots ◽  
Cell Imaging ◽  
Water Soluble ◽  
Fluorescence Signal ◽  
Selective Detection ◽  
Cupric Ion ◽  
Sensing System ◽  
Wide Range ◽  
Low Toxicity ◽  
Fluorescent Carbon Dots

A novel sensing system has been designed for the detection of cupric ions. It is based on the quenched fluorescence signal of carbon dots (CDs), which were carbonized from poly(vinylpyrrolidone) (PVP) and L-Cysteine (CYS). Cupric ions interact with the nitrogen and sulfur atoms on surface of the CDs to form an absorbed complex; this results in strong quenching of the fluorescence of the CDs via a fast metal-to-ligand binding affinity. The synthesized water-soluble CDs also exhibited a quantum yield of 7.6%, with favorable photoluminescent properties and good photostability. The fluorescence intensity of the CDs was very stable in high ionic strength (up to 1.0 M NaCl) and over a wide range of pH levels (2.0–12.0). This facile method can therefore develop a sensor that offers reliable, fast, and selective detection of cupric ions with a detection limit down to 0.15 μM and a linear range from 0.5 to 7.0 μM (R2 = 0.980). The CDs were used for cell imaging, observed that they were low toxicity to Tramp C1 cells and exhibited blue and green and red fluorescence under a fluorescence microscope. In summary, the CDs exhibited excellent fluorescence properties, and could be applied to the selective and sensitive detection of cupric ion and multicolor cell imaging.

scholarly journals Fluorescent N-doped carbon dots from bacterial cellulose for highly sensitive bacterial detection

BioResources ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 78-88
Author(s):  
Shunli Li ◽  
Xin Zhao ◽  
Yujie Zhang ◽  
Honglei Chen ◽  
Yu Liu
Keyword(s):  
Bacterial Cellulose ◽  
Carbon Dots ◽  
High Performance ◽  
Hydrothermal Carbonization ◽  
Excitation Wavelength ◽  
Particle Sizes ◽  
Bacterial Detection ◽  
Highly Sensitive ◽  
Wide Range ◽  
Doped Carbon Dots

Carbon dots have good dispersion capability, strong visible fluorescence, low toxicity, and photo-induced accepting and donating abilities. Carbon dots were obtained from biomass bacterial cellulose (BC) via one-step hydrothermal carbonization. Effects of hydrothermal time and temperature on the microstructure, fluorescence, and excitation wavelength dependent photoluminescence (PL) behavior were explored for the prepared carbon dots. The results showed that the carbon dots obtained directly from the BC (C dots) had small particle sizes (2.0 to 3.0 nm) and green luminescence behavior. Conversely, the N-doped carbon dots (N-C dots) exhibited more uniform and smaller particle sizes (approximately 1.0 nm), strong blue luminescence, acceptable fluorescence lifetime, and good stability in a wide range of pH values (2.0 to 10.0). Thus, carbon dots could serve as a fluorescent material used in high performance optical cellular imaging and highly sensitive bacterial detection.

Dispersibility of carbon dots in aqueous and/or organic solvents

2018 ◽  
Vol 54 (43) ◽  
pp. 5401-5406 ◽  
Author(s):  
Pei Zhao ◽  
Liangliang Zhu
Keyword(s):  
Quantum Dots ◽  
Organic Solvents ◽  
Carbon Dots ◽  
Luminescence Properties ◽  
Wide Range ◽  
Low Toxicity

Carbon dots have a wide range of applications in biological and medical fields as an alternative to quantum dots because of their low toxicity and excellent luminescence properties.

Practical Correction of Three Fold Astigmatism in the Philips CM TEM

1996 ◽  
Vol 54 ◽  
pp. 418-419
Author(s):  
Arno J. Bleeker ◽  
Mark H.F. Overwijk ◽  
Max T. Otten
Keyword(s):  
Optical Properties ◽  
Phase Contrast ◽  
The Other ◽  
Objective Lens ◽  
Symmetric Part ◽  
A Posteriori ◽  
Contrast Transfer Function ◽  
High Brightness ◽  
Rotationally Symmetric ◽  
Brightness Field

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

Sign in / Sign up

Export Citation Format

Share Document