scholarly journals Assembly of Carbon Dots into Frameworks with Enhanced Stability and Antibacterial Activity

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Pengfei Zhuang ◽  
Kuo Li ◽  
Daoyong Li ◽  
Haixia Qiao ◽  
Yifeng E ◽  
...  

AbstractCarbon dots (CDs) have been widely used as antimicrobials due to their active surface, but some CDs suffer instability. Therefore, the relative applications such as the antibacterial activity may not be reliable for long-term use. Herein, we synthesize CDs with blue fluorescence by a hydrothermal process. Thereafter, polyethylenimine was applied for the assembly of CDs into CDs-based frameworks (CDFs). The CDFs exhibited quenched fluorescence but showed more stable properties based on the scanning electron microscope and zeta potential investigations. Both CDs and CDFs show antibacterial activity toward Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), but CDFs exhibited better antibacterial performance, and S. aureus could be completely inhibited with the minimum inhibitory concentration of 30 μg/mL. This reveals CDFs magnify both the stability and antibacterial activity, which would be more promising for practical applications. Graphic abstract

2016 ◽  
Vol 5 (04) ◽  
pp. 4512
Author(s):  
Jackie K. Obey ◽  
Anthoney Swamy T* ◽  
Lasiti Timothy ◽  
Makani Rachel

The determination of the antibacterial activity (zone of inhibition) and minimum inhibitory concentration of medicinal plants a crucial step in drug development. In this study, the antibacterial activity and minimum inhibitory concentration of the ethanol extract of Myrsine africana were determined for Escherichia coli, Bacillus cereus, Staphylococcus epidermidis and Streptococcus pneumoniae. The zones of inhibition (mm±S.E) of 500mg/ml of M. africana ethanol extract were 22.00± 0.00 for E. coli,20.33 ±0.33 for B. cereus,25.00± 0.00 for S. epidermidis and 18. 17±0.17 for S. pneumoniae. The minimum inhibitory concentration(MIC) is the minimum dose required to inhibit growth a microorganism. Upon further double dilution of the 500mg/ml of M. africana extract, MIC was obtained for each organism. The MIC for E. coli, B. cereus, S. epidermidis and S. pneumoniae were 7.81mg/ml, 7.81mg/ml, 15.63mg/ml and 15.63mg/ml respectively. Crude extracts are considered active when they inhibit microorganisms with zones of inhibition of 8mm and above. Therefore, this study has shown that the ethanol extract of M. africana can control the growth of the four organisms tested.


Author(s):  
Olufunmiso O. Olajuyigbe ◽  
Morenike O. Adeoye-Isijola ◽  
Otunola Adedayo

Background: Black soap is a medicinal product that could be harnessed for economic purpose if properly packaged, and misconception about its traditional use by herbalists is thrown overboard.Aims: To promote the relevance of these soaps for economic development, this study compared the antibacterial activity of black soaps with medicated soaps widely used against bacterial infections.Methods: The antibacterial activities of these soap samples were determined by agar diffusion and macrobroth dilution methods.Results: In this study, the statistical analysis of the inhibition zones showed that black soaps were significantly (p < 0.05) more active than medicated soaps used against the test bacterial isolates. The black soaps inhibited and killed the isolates better than the medicated soaps at the different concentrations used. The minimum inhibitory concentration for Klebsiella pneumoniae and Enterococcus faecalis ranged between 0.125 mg/mL and 2 mg/mL, Staphylococcus aureus (0.25–4) mg/mL, Escherichia coli (0.125–4) mg/mL and Pseudomonas aeruginosa (1–4) mg/mL. The result showed that K. pneumoniae and E. faecalis were the most susceptible, followed by E. faecalis > E. coli > S. aureus > P. aeruginosa.Conclusion: As a valuable medicinal output derivable from organic waste product that could be converted to wealth, African black soap production, utilisation and commercialisation have tremendous economic potentials. These soaps showed significant antibacterial activity greater than those of the medicated soaps. Hence, their use could be a better option in place of commercially available medicated and antiseptic soaps because of the degree of antibacterial activities they exhibited.


2020 ◽  
Vol 26 (6) ◽  
pp. 200454-0
Author(s):  
Sabaoon Shamshad ◽  
Jamshaid Rashid ◽  
Ihsan-ul-haq ◽  
Naseem Iqbal ◽  
Saif Ullah Awan

Multidrug resistance of bacteria is an emerging human health hazard and warrants development of novel antibacterial agents with more effective mode of action. Here, zinc oxide and silver nanomaterials were prepared using Ficus palmata Forssk leaf extract with efficient antibacterial activity. SEM coupled with EDS confirmed the spherical symmetry with average particle diameter 50 to 65 nm while the XRD confirmed crystalline face centered cubic structure of silver and hexagonal crystallize phase of zinc oxide nanoparticles. Antibacterial activity was evaluated for 8 pathogenic bacterial strains including 3 drug resistant pathogenic strains. The nanoparticles showed enhanced growth inhibition for resistant strains in comparison with the broad-spectrum antibiotics i.e. roxithromycin and cefixime. Minimum inhibitory concentration in μg.mL<sup>-1</sup> of silver nanoparticles was found to be as low as 33.3 for resistant Streptococcus haemolyticus; 11.1 for Staphylococcus aureus and E Coli; and 3.7 μg.mL<sup>-1</sup> for resistant Pseudomonas aeruginosa. Similarly, the minimum inhibitory concentration of zinc oxide nanoparticles was found to be 100 μg.mL<sup>-1</sup> against resistant Streptococcus haemolyticus and Staphylococcus aureus; 11.1 μg.mL<sup>-1</sup> for resistant Pseudomonas aeruginosa; and 3.7 μg.mL<sup>-1</sup> against resistant E coli. Ficus palmata Forssk leaf extracts can be explored effectively for synthesizing active antibacterial nanomaterials as a non-toxic and environmentally benign synthesis route.


2014 ◽  
Vol 77 (9) ◽  
pp. 1599-1604 ◽  
Author(s):  
MAHBOUBEH MIRHOSSEINI ◽  
VAHID ARJMAND

Practical applications of different concentrations (0, 1, 2, 4, 6, and 8 mM) of zinc oxide (ZnO) suspensions containing 1% acetic acid were investigated against the pathogenic bacteria Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Bacillus cereus. ZnO suspensions (0, 1, 3, 6, and 8 mM) containing acetic acid had a significant inhibitory effect on the growth of L. monocytogenes, E. coli, and S. aureus during 12 h of incubation, and the 8 mM suspensions of ZnO were the most effective against all the strains. These data suggested that the antibacterial activity of ZnO was concentration dependent. Thus, 6 and 8 mM ZnO were selected for further studies in meat. ZnO nanoparticles reduced initial growth of all inoculated strains in meat. To our knowledge, this is the first report describing the antibacterial activity of ZnO nanoparticles in meat and indicates the potential of these nanoparticles as an antibacterial agent in the food industry.


2018 ◽  
Vol 13 (7) ◽  
pp. 1934578X1801300 ◽  
Author(s):  
Subrat Kumar Bhattamisra ◽  
Chew Hui Kuean ◽  
Lee Boon Chieh ◽  
Vivian Lee Yean Yan ◽  
Chin Koh Lee ◽  
...  

The antibacterial activity of geraniol and its effect in combination with ampicillin, amoxicillin and clarithromycin against Staphylococcus aureus, Escherichia coli and Helicobacter pylori was tested. The minimum inhibitory concentrations (MICs) and combinatory effects of geraniol against the bacteria were assessed by using the modified broth microdilution and checkerboard assay, respectively. The combinatory effect is expressed as fractional inhibitory concentration index (FICI). The MIC of geraniol against S. aureus, E. coli and H. pylori was found to be 11200, 5600, and 7325 μg/mL, respectively. A significant synergistic effect was observed with geraniol and ampicillin against S. aureus with FICI in the range 0.19 to 0.32. Geraniol and ampicillin exhibited a partial synergistic effect against E. coli. A similar effect was observed with geraniol and clarithromycin against S. aureus. A partial synergistic effect was observed with clarithromycin and geraniol against H. pylori with the FICI value in the range 0.86 to 0.89. An additive effect was observed with geraniol and amoxicillin combination against H. pylori. However, the amoxicillin and clarithromycin dose was reduced by thirty-two fold when combined with geraniol against H. pylori. The anti- H. pylori effect of geraniol with clarithromycin and amoxicillin could be of potential interest in the treatment of H. pylori infection and associated ulcers in humans. Further, geraniol, in combination with other antibiotics, has substantial therapeutic potential against S. aureus and E.coli infection.


Author(s):  
Ashish Srivastava ◽  
D. B. Mondal

The study was conducted to investigate the antibacterial efficacy against enteropathogenic E. coli of plants commonly used to treat calf-diarrhoea. Methanolic extracts of six plants (Aegle marmelos, Curcuma longa, Dalbergia sissoo, Mangifera indica, Psidium guajava and Punica granatum) were screened for their antibacterial property against enteropathogenic E. coli by standard disc diffusion method. Minimum inhibitory concentration (MIC) and of the extract exhibiting highest antibacterial activity was estimated by broth dilution method and minimum bactericidal concentration (MBC) was measured by streaking the contents of MIC tubes on nutrient agar plates. Among the six extracts tested, only extracts of Curcuma longa, Psidium guajava and Punica granatum exhibited antibacterial activity against E. coli. Out of these three, Punica granatum extract was found to be most effective with a mean inhibition zone of 14.67±0.577 mm followed by Psidium guajava (9.67±0.577 mm) and Curcuma longa (8.67±0.577 mm), produced by the disc containing 8.00 mg of respective extract. Minimum inhibitory concentration and minimum bactericidal concentration of the Punica granatum extract were estimated to be 02.00 mg/mL and 03.00 mg/mL respectively. These findings suggest that methanolic extracts of Curcuma longa, Psidium guajava and Punica granatum possess antibacterial activity against enteropathogenic E.coli


2014 ◽  
Vol 1 (1) ◽  
pp. 5
Author(s):  
Umasankar Kulandaivelu ◽  
Bhawatha Chawada ◽  
Shireesha Boyapati ◽  
Alavala Rajasekhar Reddy

Arylalkylidene derivatives of aminotriazoles (3a-3j) were synthesized and tested for their antimicrobial and anticancer activity. Four non-pathogenic bacteria [E. coli (NCIM 2068), K. pneumoniae (NCIM 2957), S. aureus (NCIM 2079), B. subtilis (NCIM 2921)] two fungi [C. albicans, A. niger] and two cancer cell lines [HBL-100 and HT-29] were employed in the study. All the compounds were found to have better antibacterial activity against B. subtilis than Ciprofloxacin (standard) and compound 3i was equivalent to Ciprofloxacin in inhibiting S. aureas. Similarly all the compounds inhibited the growth of A. niger better than Fluconazole and compound 3c was equivalent to Fluconazole (standard) in inhibiting C. albicans. In case of anticancer activity none of the molecule exhibited activity better than the standard used (Methotrexate), though they have inhibitory concentration at submicromolar level.


2021 ◽  
Vol 21 (3) ◽  
pp. 1598-1605
Author(s):  
Ngoc Bao Tri Pham ◽  
Vu Khanh Trang Le ◽  
Thi Thu Thao Bui ◽  
Nguyen Gia Linh Phan ◽  
Quoc Vinh Tran ◽  
...  

Ag/SiO2 colloidal nanocomposites (NCs) were prepared through the semi-continuous chemical reduction of silver ions on a silica surface; NaBH4 was used as a primary reducing agent, while carboxymethyl cellulose (CMC) served as a secondary reductant and a stabilizer at low temperature. Silver nanoparticles (AgNPs) of an average diameter of 3.89±0.18 nm were uniformly and densely dispersed on the SiO2 surface, forming 218.6-nm-sized Ag/SiO2 NCs. The zeta potential of the Ag/SiO2 NCs (−92.6 mV) was more negative than that of silica (−24 mV), indicating their high long-term stability. Furthermore, their proposed formation mechanism was confirmed via Fourier transform infrared spectroscopy. Then, the bactericidal effect of the Ag/SiO2 was evaluated based on their minimal inhibitory concentration (MIC) against Ralstonia solanacearum 15 (R. solanacearum 15); it was 62.5 ppm, much lower than that of conventional AgNPs (500 ppm). Therefore, these highly stable Ag/SiO2 colloidal NCs with more effective antibacterial activity than conventional AgNPs are a promising nanopesticide in agriculture.


2020 ◽  
Vol 7 (2) ◽  
pp. 289-295
Author(s):  
Mohammad Arfi Setiawan ◽  
Mita Dewi Retnoningrum ◽  
Febriyandhi Yahya ◽  
Resa Ragil Andika ◽  
Dyan Hatining Ayu Sudarni

Antibacterial Activity of Citrus seed (Citrus reticulata) Extract on Escherichia coli Indonesian agriculture provides a resource of medicinal plants whose potential needs to be explored in order to benefit society. One of them is the use of Siam orange seeds (Citrus reticulata) which has the potential for the production of antibacterial compounds. This study aims to test the antibacterial activity of the ethanol and n-hexane extract of orange seeds. The extract was obtained through maceration techniques using ethanol and n-hexane as solvents. The antibacterial activity test of orange seeds against Escherichia coli used the paper disc diffusion method with nutrient agar (NA) media. The concentration of orange seed extract for the determination of MIC (Minimum Inhibitory Concentration) was 0.5, 2, 8, 10, 20 mg mL-1. The results showed that the ethanol and n-hexane extract of orange seeds had antibacterial activity against E. coli. However, the ethanol extract had a higher antibacterial effect than the n-hexane orange seed extract. From the results of this study, it is hoped that the waste of orange seeds will provide beneficial contribution for pharmaceutical development. Pertanian Indonesia memiliki sumber tanaman obat yang perlu digali potensinya agar bermanfaat bagi masyarakat. Salah satunya pemanfaatan biji jeruk siam (Citrus reticulata) yang berpotensi menghasilkan senyawa antibakteri. Penelitian ini bertujuan untuk menguji aktivitas antibakteri ekstrak etanol dan n-heksana biji jeruk. Ekstrak diperoleh melalui teknik maserasi menggunakan pelarut etanol dan n-heksana. Uji aktivitas antibakteri biji jeruk terhadap Escherichia coli menggunakan metode difusi paper disc dengan media nutrient agar (NA). Konsentrasi ekstrak biji jeruk untuk penentuan MIC (Minimum Inhibitory Concentration) adalah 0,5, 2, 8, 10, 20 mg mL-1. Hasil penelitian menunjukkan bahwa ekstrak etanol dan n-heksana biji jeruk memiliki aktivitas antibakteri terhadap E. coli. Namun, ekstrak etanol memiliki efek antibakteri yang lebih tinggi dibandingkan ekstrak biji jeruk n-heksana. Dari hasil penelitian ini, limbah biji jeruk diharapkan dapat memberikan kontribusi bermanfaat bagi pengembangan farmasi.


2021 ◽  
Author(s):  
Elizaveta Sviridova ◽  
Alexandre Barras ◽  
Evgenii Plotnikov ◽  
Antonio Di Martino ◽  
Dominique Deresmes ◽  
...  

In this contribution, we report a facile functionalization method of carbon dots (CDs) by tetraalkylammonium moieties using diazonium chemistry to improve their antibacterial activity against Gram-positive and Gram-negative bacteria. CDs were modified by novel diazonium salts bearing tetraalkylammonium moieties (TAA) with different alkyl chains (C2, C4, C9, C12) for the optimization of antibacterial activity. The functionalized CDs were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV-vis) absorption spectrophotometry and fluorescence spectroscopy to confirm the covalent binding of TAA onto the CDs’ surface. Variation of the alkyl chain allows to reach the strongest antibacterial effect for CDs-C9 towards Gram-positive S. aureus (MIC 3.09±1.10 µg mL-1) and Gram-negative E. coli (MIC 7.93±0.17 µg mL-1) bacteria. In addition, the antibiofilm properties of the CDs-C9 were assessed; full biofilm inhibition was achieved after 6 h (64 µg mL-1) and 2 h (128 µg mL-1) treatment for S. aureus biofilm and >60% suppression of biofilm mass after 6 h (128 µg mL-1) for E. coli biofilm. CDs-C9 demonstrated good biocompatibility on mouse fibroblast (NIH/3T3), HeLa and U-87 MG cell lines for concentrations up to 256 µg mL-1. Collectively, our work highlights the correlation between the surface chemistry of CDs and their antimicrobial performance.


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