Crystalline-Induced Luminescence of Carbon Dots for the WLED and Fingerprint Recognition

: 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.

Download Full-text

Nitrogen and Sulfur Co-doped Fluorescent Carbon Dots for the Detection of Morin and Cell Imaging

Current Analytical Chemistry ◽

10.2174/1573411014666180904104629 ◽

2018 ◽

Vol 15 (1) ◽

pp. 47-55

Author(s):

Xuebing Li ◽

Haifen Yang ◽

Ning Wang ◽

Tijian Sun ◽

Wei Bian ◽

...

Keyword(s):

Microwave Heating ◽

Fluorescent Probe ◽

Fluorescence Intensity ◽

Carbon Dots ◽

Cell Imaging ◽

Water Soluble ◽

Heating Process ◽

X Ray ◽

Doped Carbon Dots ◽

Co Doped

Background: Morin has many pharmacological functions including antioxidant, anticancer, anti-inflammatory, and antibacterial effects. It is commonly used in the treatment of antiviral infection, gastropathy, coronary heart disease and hepatitis B in clinic. However, researches have shown that morin is likely to show prooxidative effects on the cells when the amount of treatment is at high dose, leading to the decrease of intracellular ATP levels and the increase of necrosis process. Therefore, it is necessary to determine the concentration of morin in biologic samples. Method: Novel water-soluble and green nitrogen and sulfur co-doped carbon dots (NSCDs) were prepared by a microwave heating process with citric acid and L-cysteine. The fluorescence spectra were collected at an excitation wavelength of 350 nm when solutions of NSCDs were mixed with various concentrations of morin. Results: The as-prepared NSCDs were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The fluorescence intensity of NSCDs decreased significantly with the increase of morin concentration. The fluorescence intensity of NSCDs displayed a linear response to morin in the concentration 0.10-30 μM with a low detection limit of 56 nM. The proposed fluorescent probe was applied to analysis of morin in human body fluids with recoveries of 98.0-102%. Conclusion: NSCDs were prepared by a microwave heating process. The present analytical method is sensitive to morin. The quenching process between NSCDs and morin is attributed to the static quenching. In addition, the cellular toxicity on HeLa cells indicated that the as-prepared NSCDs fluorescent probe does not show obvious cytotoxicity in cell imaging. Our proposed method possibly opens up a rapid and nontoxic way for preparing heteroatom doped carbon dots with a broad application prospect.

Download Full-text

Nitrogen-doped carbon dots from Hutai-8 grape skin and their application in Hg2+ detection

Current Nanoscience ◽

10.2174/1573413716999200819201126 ◽

2020 ◽

Vol 16 ◽

Author(s):

Pan Zhang ◽

Shun-Sheng Zhao ◽

JiaJia Wang ◽

Xiang Rong Liu

Keyword(s):

Heavy Metal ◽

Carbon Source ◽

Fluorescence Quenching ◽

Hydrothermal Method ◽

Water Samples ◽

Carbon Dots ◽

Mercury Ions ◽

Grape Skin ◽

Fluorescent Carbon Dots ◽

Fluorescent Carbon

Background: In recent years, environmental pollution and heavy metal pollution caused by rapid urbanization and industrialization have become increasingly serious. Among them, mercury (II) ion (Hg2+) is one of the highly toxic heavy metal ions, and its pollution comes from various natural resources and human activities. Therefore, people attach great importance to the development of analytical methods for effective analysis and sensitive detection of Hg2+ . Objective: Using grape skin as a green and environmental friendly carbon source, to synthesize fluorescent carbon dots, and try to apply them to the detect the concentration of Hg2+ in water. Method: Using "Hutai No. 8" grape skin as carbon source, fluorescent carbon dots were synthesized by one-step hydrothermal method. Structure and fluorescent properties of the carbon dots were tested using TEM, XPS, XRD and other characterization instruments, and their utilization on detection of mercury ions in the actual water samples was explored. Results: The CDs had a particle size of about 4.8 nm and a spherical shape. There are N-H, C-N, C=O and other functional groups on the surface. It was found that Hg2+ has obvious fluorescence quenching effect on CDs, and thus CDs fluorescence quenching method to detect the concentration Hg2+ was established, and the detection limit is 3.7 μM, which could be applied to test the concentration of Hg2+ in water samples. Conclusion: Using grape skin as carbon source, fluorescent carbon dots were successfully synthesized by hydrothermal method. Carbon dots were used to detect mercury ions in water, and a method for detecting mercury ions in actual water samples was established.

Download Full-text

Evaluation of the effectiveness of different image skeletonization methods in biometric security systems

International Journal of Sensors Wireless Communications and Control ◽

10.2174/2210327910666201210151809 ◽

2020 ◽

Vol 10 ◽

Author(s):

Mariya Nazarkevych ◽

Serhii Dmytruk ◽

Volodymyr Hrytsyk ◽

Olha Vozna ◽

Anzhela Kuza ◽

...

Keyword(s):

Experimental Studies ◽

Fingerprint Recognition ◽

Good Time ◽

Gabor Filtering ◽

Security Systems ◽

Thinning Algorithm ◽

Biometric Security ◽

Recognition Quality ◽

Control And Management ◽

The Internet Of Things

Background: Systems of the Internet of Things are actively implementing biometric systems. For fast and high-quality recognition in sensory biometric control and management systems, skeletonization methods are used at the stage of fingerprint recognition. The analysis of the known skeletonization methods of Zhang-Suen, Hilditch, Ateb-Gabor with the wave skeletonization method has been carried out and it shows a good time and qualitative recognition results. Methods: The methods of Zhang-Suen, Hildich and thinning algorithm based on Ateb-Gabor filtration, which form the skeletons of biometric fingerprint images, are considered. The proposed thinning algorithm based on Ateb-Gabor filtration showed better efficiency because it is based on the best type of filtering, which is both a combination of the classic Gabor function and the harmonic Ateb function. The combination of this type of filtration makes it possible to more accurately form the surroundings where the skeleton is formed. Results: Along with the known ones, a new Ateb-Gabor filtering algorithm with the wave skeletonization method has been developed, the recognition results of which have better quality, which allows to increase the recognition quality from 3 to 10%. Conclusion: The Zhang-Suen algorithm is a 2-way algorithm, so for each iteration, it performs two sets of checks during which pixels are removed from the image. Zhang-Suen's algorithm works on a plot of black pixels with eight neighbors. This means that the pixels found along the edges of the image are not analyzed. Hilditch thinning algorithm occurs in several passages, where the algorithm checks all pixels and decides whether to replace a pixel from black to white if certain conditions are satisfied. This Ateb-Gabor filtering will provide better performance, as it allows to obtain more hollow shapes, organize a larger range of curves. Numerous experimental studies confirm the effectiveness of the proposed method.

Download Full-text