scholarly journals P-Doped Carbon Quantum Dots with Antibacterial Activity

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1116
Author(s):  
Shuiqin Chai ◽  
Lijia Zhou ◽  
Shuchen Pei ◽  
Zhiyuan Zhu ◽  
Bin Chen
Keyword(s):  
Quantum Dots ◽  
Antibacterial Activity ◽  
Bacterial Infections ◽  
Fluorescence Emission ◽  
Carbon Quantum Dots ◽  
Microbial Pathogens ◽  
Electronic Interaction ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Zeta Potential Analysis

It is a major challenge to effectively inhibit microbial pathogens in the treatment of infectious diseases. Research on the application of nanomaterials as antibacterial agents has evidenced their great potential for the remedy of infectious disease. Among these nanomaterials, carbon quantum dots (CQDs) have attracted much attention owing to their unique optical properties and high biosafety. In this work, P-doped CQDs were prepared by simple hydrothermal treatment of m-aminophenol and phosphoric acid with fluorescence emission at 501 nm when excited at 429 nm. The P-doped CQDs showed effective antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The minimal inhibitory concentrations (MICs) of P-doped CQD were 1.23 mg/mL for E. coli and 1.44 mg/mL for S. aureus. Furthermore, the morphologies of E. coli cells were damaged and S. aureus became irregular when treated with the P-doped CQDs. The results of zeta potential analysis demonstrated that the P-doped CQDs inhibit antibacterial activity and destroy the structure of bacteria by electronic interaction. In combination, the results of this study indicate that the as-prepared P-doped CQDs can be a promising candidate for the treatment of bacterial infections.

scholarly journals A novel bis(pyrazolyl)methane compound as a potential agent against Gram-positive bacteria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pedro Seguí ◽  
John J. Aguilera-Correa ◽  
Elena Domínguez-Jurado ◽  
Christian M. Sánchez-López ◽  
Ramón Pérez-Tanoira ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Effect ◽  
Eukaryotic Cell ◽  
Liver Carcinoma ◽  
Gram Positive ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Therapeutic Compounds ◽  
Toxic Concentrations

AbstractThis study was designed to propose alternative therapeutic compounds to fight against bacterial pathogens. Thus, a library of nitrogen-based compounds bis(triazolyl)methane (1T–7T) and bis(pyrazolyl)methane (1P–11P) was synthesised following previously reported methodologies and their antibacterial activity was tested using the collection strains of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Moreover, the novel compound 2P was fully characterized by IR, UV–Vis and NMR spectroscopy. To evaluate antibacterial activity, minimal inhibitory concentrations (MICs), minimal bactericidal concentrations (MBCs), minimum biofilm inhibitory concentrations (MBICs), and minimum biofilm eradication concentrations (MBECs) assays were carried out at different concentrations (2–2000 µg/mL). The MTT assay and Resazurin viability assays were performed in both human liver carcinoma HepG2 and human colorectal adenocarcinoma Caco-2 cell lines at 48 h. Of all the synthesised compounds, 2P had an inhibitory effect on Gram-positive strains, especially against S. aureus. The MIC and MBC of 2P were 62.5 and 2000 µg/mL against S. aureus, and 250 and 2000 µg/mL against E. faecalis, respectively. However, these values were > 2000 µg/mL against E. coli and P. aeruginosa. In addition, the MBICs and MBECs of 2P against S. aureus were 125 and > 2000 µg/mL, respectively, whereas these values were > 2000 µg/mL against E. faecalis, E. coli, and P. aeruginosa. On the other hand, concentrations up to 250 µg/mL of 2P were non-toxic doses for eukaryotic cell cultures. Thus, according to the obtained results, the 2P nitrogen-based compound showed a promising anti-Gram-positive effect (especially against S. aureus) both on planktonic state and biofilm, at non-toxic concentrations.

Temperature Dependent On Activated Carbon For Their Biological Activity And Photocatalytical Degradation of Methylene Blue: A Novel Approach To Green Synthesis

2021 ◽  
Author(s):  
Amalanathan.M ◽  
Aravind.M ◽  
Sony Michael Mary.M ◽  
Razan A. Alshgari ◽  
Asma A. Alothman ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Antibacterial Activity ◽  
Activated Carbon ◽  
Hydrothermal Carbonization ◽  
Microbial Pathogens ◽  
X Ray Diffraction ◽  
E Coli ◽  
Novel Approach ◽  
Transmission Electron ◽  
Ft Ir

Abstract In this work, jasmine flower derived activated carbon were successfully synthesized by hydrothermal carbonization process at the different annealing temperature. The Crystallinity, phase, structural, morphological and optical properties of activated carbon were investigated using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), and UV-visible spectroscopy analysis. The graphitic phase of carbon was obtained from the XRD pattern. Surface morphology reveals irregular-shaped nanoparticles. The photodegradation of methylene blue (MB) was carried out under the visible light irradiation technique to study its photocatalytic activity. The activated carbon obtained at 400oC, 500oC and 600oC shows a photocatalytic degradation efficiency of 86%, 90%, and 94%, respectively. Antibacterial activity of activated carbon was examined against S. Aureus (MTCC-737) and E-Coli (MTCC- 443) microbial pathogens, and their potent antibacterial activity was examined from the zone of inhibition layer.

FRET Study Between Carbon Quantum Dots and Malachite Green by Steady-State and Time-Resolved Fluorescence Spectroscopy

2020 ◽  
Vol 10 (3) ◽  
pp. 178-188
Author(s):  
Bipin Rooj ◽  
Ankita Dutta ◽  
Debojyoti Mukherjee ◽  
Sahidul Islam ◽  
Ujjwal Mandal
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Fluorescence Spectroscopy ◽  
Malachite Green ◽  
Dye Degradation ◽  
Fluorescence Emission ◽  
Carbon Quantum Dots ◽  
Time Resolved Fluorescence ◽  
Physical Processes ◽  
Time Resolved

Background: Understanding the interaction between different organic dyes and carbon quantum dots helps us to understand several photo physical processes like electron transfer, energy transfer, molecular sensing, drug delivery and dye degradation processes etc. Objective: The primary objective of this study is to whether the carbon quantum dots can act as an electron donor and can participate in the different photo physical processes. Methods: In this work, Carbon Quantum Dots (CQDLs) are synthesized in most economical and simple carbonization method where petals of Nelumbo nucifera L. are used as a carbon precursor. The synthesized CQDLs were characterized by using experimental techniques like UV−Vis absorption, FT-IR, Transmission Electron Microscopy (TEM), steadystate and time-resolved fluorescence spectroscopy. Results: The spectral analysis shows that the so synthesized CQDLs are spherical in shape and its diameter is around 4.2 nm. It shows the fluorescence emission maximum at 495 nm with a quantum yield of 4%. In this work the interaction between Carbon Quantum Dots (CQDLs) and an organic dye Malachite Green (MG) is studied using fluorescence spectroscopic technique under ambient pH condition (At pH 7). The quenching mechanism of CQDLs with MG was investigated using Stern-Volmer equation and time-resolved fluorescence lifetime studies. The results show that the dominant process of fluorescence quenching is attributed to Forster Resonance Energy Transfer (FRET) having a donor acceptor distance of 53 Å where CQDLs act as a donor and MG acts as an acceptor. Conclusion: This work has a consequence that CQDLs can be used as a donor species for different photo physical processes such as photovoltaic cell, dye sensitized solar cell, and also for antioxidant activity study.

scholarly journals 1,4-Naphthoquinone Analogues: Potent Antibacterial Agents and Mode of Action Evaluation

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1437 ◽  
Author(s):  
Palanisamy Ravichandiran ◽  
Sunirmal Sheet ◽  
Dhanraj Premnath ◽  
Ae Rhan Kim ◽  
Dong Jin Yoo
Keyword(s):  
Antibacterial Activity ◽  
Mode Of Action ◽  
Bacterial Infections ◽  
Antibacterial Agents ◽  
Annexin V ◽  
Ros Generation ◽  
Redox Potentials ◽  
Bacterial Strains ◽  
E Coli ◽  
New Class

1,4-Naphthoquinones have antibacterial activity and are a promising new class of compound that can be used to treat bacterial infections. The goal was to improve effective antibacterial agents; therefore, we synthesized a new class of naphthoquinone hybrids, which contain phenylamino-phenylthio moieties as significant counterparts. Compound 4 was modified as a substituted aryl amide moiety, which enhanced the antibacterial activity of earlier compounds 3 and 4. In this study, five bacterial strains Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae) were used to evaluate the antibacterial potency of synthesized naphthoquinones using the minimal inhibitory concentration (MIC) method. Most of the studied naphthoquinones demonstrated major antibacterial activity with a MIC of 15.6 µg/mL–500 µg/mL. Selected compounds (5a, 5f and 5x) were studied for the mode of action, using intracellular ROS generation, determination of apoptosis by the Annexin V-FITC/PI assay, a bactericidal kinetic study and in silico molecular modelling. Additionally, the redox potentials of the specified compounds were confirmed by cyclic voltammetry (CV).

One-pot synthesis of natural amine-modified biocompatible carbon quantum dots with antibacterial activity

2020 ◽  
Vol 580 ◽  
pp. 30-48 ◽  
Author(s):  
Milica Gagic ◽  
Silvia Kociova ◽  
Kristyna Smerkova ◽  
Hana Michalkova ◽  
Milena Setka ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Antibacterial Activity ◽  
Carbon Quantum Dots ◽  
One Pot ◽  
One Pot Synthesis

scholarly journals Robust Antibacterial Activity of Tungsten Oxide (WO3-X) Nanodots

2018 ◽  
Author(s):  
Guangxin Duan ◽  
Lu Chen ◽  
Zhifeng Jing ◽  
Phil De Luna ◽  
Lin Wen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antibacterial Activity ◽  
Tungsten Oxide ◽  
Bacterial Infections ◽  
Antibacterial Agents ◽  
Inorganic Materials ◽  
Cell Counting ◽  
Resonance Spectroscopy ◽  
Synthetic Approach ◽  
E Coli

AbstractAntibacterial agents are an important tool in the prevention of bacterial infections. Inorganic materials are attractive due to their high stability under a variety of conditions compared to organic antibacterial agents. Herein tungsten oxide nanodots (WO3-X), synthesized by a simple one-pot synthetic approach, was found to exhibit efficient antibacterial capabilities. The analyses with colony-forming units (CFU) showed excellent antibacterial activity of WO3-X against both gram-negative E. coli (Escherichia coli) and gram-positive S. aureus (Staphylococcus aureus) strains. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed clear damage to the bacterial cell membranes, which was further confirmed by molecular dynamics simulations. Additionally, exposure to simulated sunlight was found to further increase germicidal activity of WO3-X nanodots – a 30-minute exposure to sunlight (combining 50 μg/mL WO3-X nanodots) showed a 70% decrease in E. coli viability compared to without exposure. Electron spin resonance spectroscopy (ESR) was used to elucidate the underlying mechanism of this photocatalytic activity through the generation of hydroxyl radical species. Cell counting kit-8 (CCK-8) and the live/dead assay were further employed to evaluate the cytotoxicity of WO3-X nanodots on eukaryotic cells, which demonstrated their general biocompatibility. In all, our results suggest WO3-X nanodots have considerable potential in antibacterial applications, while also being biocompatible at large.

scholarly journals Green Synthesis and Characterization of Silver Nanoparticles using Crude Extract of Crotalaria burhia

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Khalil Ahmad ◽  
Raeesa Noor ◽  
Muhammad Younus ◽  
Akram Chohan ◽  
Ume Habiba ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Zeta Potential ◽  
Green Synthesis ◽  
Crude Extract ◽  
Bacterial Infections ◽  
Synthesis And Characterization ◽  
Phytochemical Analysis ◽  
E Coli

Background: Appearance of antibiotic resistance has raised the demand to find alternative therapies and modified drug delivery system of medicinal plants to treat bacterial infections. Objective: The aim of this study is the green synthesis and characterization of silver nanoparticles by using crude extract of Crotalaria burhia and to evaluate their antibacterial potential. Methods: The roots and stems of plant were used to prepare the crude extract. The phytochemical analysis of different compounds in extract was performed. 1mM AgNO3 and different concentrations of plant extract were used for the green synthesis of silver nanoparticles. The particles size and zeta potential were measured by zeta sizer while surface morphology of silver nanoparticles was observed with Scanning Electron Microscope (SEM). The antibacterial activity of silver nanoparticles was performed by 96 well microdilution plate method. Results: The particle size and zeta potential of optimized formulation was 92 nm and -24.8 mV. The SEM analysis showed that silver nanoparticles are irregular and spherical shape. The antibacterial activity showed that MIC value of silver nanoparticles was lower for E. coli than S. aureus. Conclusion: Silver nanoparticles possess potent bactericidal activity against E. coli and moderate activity against S. aureus. It had been concluded that these nanoparticles can be used against multi-drug resistant bacterial infections.

scholarly journals Benzohydrazide and Phenylacetamide Scaffolds: New Putative ParE Inhibitors

2021 ◽  
Vol 9 ◽  
Author(s):  
Vidyasrilekha Yele ◽  
Bharat Kumar Reddy Sanapalli ◽  
Ashish D. Wadhwani ◽  
Afzal Azam Mohammed
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Activity ◽  
Bacterial Infections ◽  
Vero Cells ◽  
Selectivity Index ◽  
Major Life ◽  
E Coli ◽  
Antibiotic Effect ◽  
Life Threatening ◽  
Approved Drugs

Antibacterial resistance (ABR) is a major life-threatening problem worldwide. Rampant dissemination of ABR always exemplified the need for the discovery of novel compounds. However, to circumvent the disease, a molecular target is required, which will lead to the death of the bacteria when acted upon by a compound. One group of enzymes that have proved to be an effective target for druggable candidates is bacterial DNA topoisomerases (DNA gyrase and ParE). In our present work, phenylacetamide and benzohydrazides derivatives were screened for their antibacterial activity against a selected panel of pathogens. The tested compounds displayed significant antibacterial activity with MIC values ranging from 0.64 to 5.65 μg/mL. Amongst 29 title compounds, compounds 5 and 21 exhibited more potent and selective inhibitory activity against Escherichia coli with MIC values at 0.64 and 0.67 μg/mL, respectively, and MBC at onefold MIC. Furthermore, compounds exhibited a post-antibiotic effect of 2 h at 1× MIC in comparison to ciprofloxacin and gentamicin. These compounds also demonstrated the concentration-dependent bactericidal activity against E. coli and synergized with FDA-approved drugs. The compounds are screened for their enzyme inhibitory activity against E. coli ParE, whose IC50 values range from 0.27 to 2.80 μg/mL. Gratifyingly, compounds, namely 8 and 25 belonging to the phenylacetamide series, were found to inhibit ParE enzyme with IC50 values of 0.27 and 0.28 μg/mL, respectively. In addition, compounds were benign to Vero cells and displayed a promising selectivity index (169.0629–951.7240). Moreover, compounds 1, 7, 8, 21, 24, and 25 (IC50: <1 and Selectivity index: >200) exhibited potent activity in reducing the E. coli biofilm in comparison with ciprofloxacin, erythromycin, and ampicillin. These astonishing results suggest the potential utilization of phenylacetamide and benzohydrazides derivatives as promising ParE inhibitors for treating bacterial infections.

scholarly journals Quaternized carbon quantum dots with broad-spectrum antibacterial activity for treatment of wounds infected with mixed bacteria

2020 ◽  
Author(s):  
Zhao Cheng-fei ◽  
Xuewen Wang ◽  
Luying Yu ◽  
Lina Wu ◽  
Xiaoli Hao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Antibacterial Activity ◽  
Broad Spectrum ◽  
Ribosomal Proteins ◽  
Carbon Quantum Dots ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Testing Stage ◽  
Mixed Bacteria

Abstract Quaternized carbon quantum dots (qCQDs) with broad-spectrum antibacterial activity were synthesized by a simple green “one-pot” method using dimethyl diallyl ammonium chloride and glucose as reaction precursors. The qCQDs showed satisfactory antibacterial activity against both gram-positive and gram-negative bacteria. In rat models of wounds infected with mixed bacteria, qCQDs obviously restored the weight of rats, significantly reduced the death of rats from severe infection, and promoted the recovery and healing of infected wounds. Biosafety tests confirmed that qCQDs had no obvious toxic and side effects during the testing stage. The analysis of quantitative proteomics revealed that qCQDs mainly acted on the ribosomal proteins of gram-positive bacteria and significantly down-regulated the metabolization-related proteins of gram-negative bacteria. Real-time quantitative PCR verified the expression levels of genes corresponding to the proteins with significant differences expressed by the two species of bacteria after treated with qCQDs. The variation trend of the detected genes was consistent with the results of proteomics, meaning that qCQDs played the antibacterial effect on bacteria with a new antibacterial mechanism.

scholarly journals Synergy between “Probiotic” Carbon Quantum Dots and Ciprofloxacin in Eradicating Infectious Biofilms and Their Biosafety in Mice

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1809
Author(s):  
Yanyan Wu ◽  
Guang Yang ◽  
Henny C. van der Mei ◽  
Linqi Shi ◽  
Henk J. Busscher ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Open Space ◽  
Carbon Quantum Dots ◽  
Probiotic Bacteria ◽  
Ros Generation ◽  
E Coli ◽  
Protein Levels ◽  
Reactive Protein ◽  
Physico Chemical ◽  
Intestinal Infections

Orally administrated probiotic bacteria can aid antibiotic treatment of intestinal infections, but their arrival at their intestinal target site is hampered by killing in the gastrointestinal tract and by antibiotics solely intended for pathogen killing. Carbon-quantum-dots are extremely small nanoparticles and can be derived from different sources, including bacteria. Here, we hypothesize that carbon-quantum-dots inherit antibacterial activity from probiotic source bacteria to fulfill a similar role as live probiotics in intestinal infection therapy. Physico-chemical analyses indicated that carbon-quantum-dots, hydrothermally derived from Bifidobacterium breve (B-C-dots), inherited proteins and polysaccharides from their source-bacteria. B-C-dots disrupted biofilm matrices of Escherichia coli and Salmonella typhimurium biofilms through extensive reactive-oxygen-species (ROS)-generation, causing a decrease in volumetric bacterial-density in biofilms. Decreased bacterial densities leave more open space in biofilms and have enhanced ciprofloxacin penetration and killing potential in an E. coli biofilm pre-exposed to probiotic B-C-dots. Pathogenic carbon-quantum-dots hydrothermally derived from E. coli (E-C-dots) did not disrupt pathogenic biofilms nor enhance E. coli killing potential by ciprofloxacin. B-C-dots were biosafe in mice upon daily administration, while E-C-dots demonstrated a decrease in white blood cell and platelet counts and an increase in C-reactive protein levels. Therefore, the way is paved for employing probiotic carbon-quantum-dots instead of viable, probiotic bacteria for synergistic use with existing antibiotics in treating intestinal infections.

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