A metal-free approach to bipyridinium salt-based conjugated porous polymers with olefin linkages

2021 ◽  
Vol 12 (11) ◽  
pp. 1661-1667
Author(s):  
Jiawei Lin ◽  
Shuai Bi ◽  
Zhongxiong Fan ◽  
Zhenzhen Fu ◽  
Zhaohui Meng ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
High Stability ◽  
Knoevenagel Condensation ◽  
Porous Polymers ◽  
Metal Free ◽  
Positively Charged

A metal-free bipyridinium salt-activated Knoevenagel condensation strategy was developed to synthesize olefin-linked conjugated porous polymers with π-extended networks, positively charged skeletons, high stability and antibacterial activity.

APPLICATIONS OF CHITOSAN-SULFATHIAZOLE AS ANTIMICROBIAL AGENT

2018 ◽  
Vol 28 (2) ◽  
pp. 429-432
Author(s):  
Dilyana Zvezdova
Keyword(s):  
Wound Healing ◽  
Antibacterial Activity ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Antimicrobial Agent ◽  
Defense Mechanisms ◽  
Solvent Casting ◽  
Casting Method ◽  
Gram Negative ◽  
Positively Charged

Chitosan, a hydrophilic biopolymer industrially obtained by N-deacetylation of chitin, can be applied as an antimicrobial agent. It highlights the applications of chitosan as an antimicrobial agent against fungi, bacteria, and viruses and as an elicitor of plant defense mechanisms. A series of novel chitosan-sulfathiazole nanocomposite (CSFZ) films were prepared by using solvent casting method for wound healing application. Fourier transform infrared spectroscopy (FTIR) was employed to ascertain the interaction between negatively charged sulfathiazole and positively charged chitosan. Moreover, the antibacterial activity of the films was investigated against gram positive and gram negative microorganisms. It was found that all CSFZ films showed good inhibitory activity against all the tested bacteria as compared to control. The above analysis suggested that the CSFZ films could be used as potential candidates for wound healing application.

Bi-doped Graphitic Carbon Nitride Nanotubes Boosts the Degradation Photocatalysis of Rhodamine B

2022 ◽  
Author(s):  
Qingqing Gao ◽  
Qian Lei ◽  
Ruoyan Miao ◽  
Manyi Gao ◽  
Fang Song ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Rhodamine B ◽  
High Stability ◽  
Carbon Nitride ◽  
Graphitic Carbon Nitride ◽  
Photocatalytic Efficiency ◽  
Metal Free ◽  
Carrier Recombination ◽  
Charge Carrier Recombination ◽  
Polymeric Carbon

Polymeric carbon nitride (PCN) is an emerging metal-free photocatalysts with high stability but is plagued by low photocatalytic efficiency due to the rapid charge carrier recombination behavior. Herein, Bi doped...

scholarly journals Molecular Characterization of a Novel Lytic Enzyme LysC from Clostridium intestinale URNW and Its Antibacterial Activity Mediated by Positively Charged N-Terminal Extension

2020 ◽  
Vol 21 (14) ◽  
pp. 4894 ◽  
Author(s):  
Magdalena Plotka ◽  
Monika Szadkowska ◽  
Maria Håkansson ◽  
Rebeka Kovačič ◽  
Salam Al-Karadaghi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Amino Acid ◽  
Hydrolytic Enzymes ◽  
Lytic Enzyme ◽  
Amino Acid Sequence Similarity ◽  
Scanning System ◽  
Strong Activity ◽  
Promising Alternative ◽  
Intrinsically Disordered ◽  
Positively Charged

Peptidoglycan hydrolytic enzymes are considered to be a promising alternative to conventional antibiotics in combating bacterial infections. To identify novel hydrolytic enzymes, we performed a database search with the sequences of two thermostable endolysins with high bactericidal activity, studied earlier in our laboratory. Both these enzymes originate from Thermus scotoductus bacteriophages MAT2119 and vB_Tsc2631. A lytic enzyme LysC from Clostridium intestinale URNW was found to have the highest amino acid sequence similarity to the bacteriophage proteins and was chosen for further analysis. The recombinant enzyme showed strong activity against its host bacteria C. intestinale, as well as against C. sporogenes, Bacillus cereus, Micrococcus luteus, and Staphylococcus aureus, on average causing a 5.12 ± 0.14 log reduction of viable S. aureus ATCC 25923 cells in a bactericidal assay. Crystallographic studies of the protein showed that the catalytic site of LysC contained a zinc atom coordinated by amino acid residues His50, His147, and Cys155, a feature characteristic for type 2 amidases. Surprisingly, neither of these residues, nor any other of the four conserved residues in the vicinity of the active site, His51, Thr52, Tyr76, and Thr153, were essential to maintain the antibacterial activity of LysC. Therefore, our attention was attracted to the intrinsically disordered and highly positively charged N-terminal region of the enzyme. Potential antibacterial activity of this part of the sequence, predicted by the Antimicrobial Sequence Scanning System, AMPA, was confirmed in our experimental studies; the truncated version of LysC (LysCΔ2–23) completely lacked antibacterial activity. Moreover, a synthetic peptide, which we termed Intestinalin, with a sequence identical to the first thirty amino acids of LysC, displayed substantial anti-staphylococcal activity with IC50 of 6 μg/mL (1.5 μM). This peptide was shown to have α-helical conformation in solution in the presence of detergents which is a common feature of amphipathic α-helical antimicrobial peptides.

A green route for methanol carbonylation

2017 ◽  
Vol 7 (20) ◽  
pp. 4818-4822 ◽  
Author(s):  
Youming Ni ◽  
Lei Shi ◽  
Hongchao Liu ◽  
Wenna Zhang ◽  
Yong Liu ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Noble Metal ◽  
High Stability ◽  
Methanol Carbonylation ◽  
Metal Free ◽  
Green Route

Halide-free and noble metal-free pyridine-modified H-mordenites exhibit high stability and selectivity in methanol carbonylation to acetic acid.

scholarly journals Metal-Free Fenton-like Photocatalysts Based on Covalent Organic Frameworks

2021 ◽  
Author(s):  
Qiaobo Liao ◽  
Can Ke ◽  
Dongni Wang ◽  
Yiying Zhang ◽  
Qingwen Han ◽  
...  
Keyword(s):  
Fenton Reaction ◽  
High Stability ◽  
Advanced Oxidation Processes ◽  
Superoxide Radical ◽  
Advanced Oxidation ◽  
Oxygen Species ◽  
Oxidation Processes ◽  
Metal Free ◽  
Layer Stacking ◽  
Opening Up

The Fenton reaction is one of the most efficient and widely used advanced oxidation processes for remediating the ever-growing water pollution. Metal-free photocatalysts for Fenton-like reactions have gathered enormous scientific interest for their advantages including board pH operation range and high stability. Herein, we demonstrate a metal-free covalent organic framework (COF)-based standalone photocatalyst with superior reactivity and reusability for Fenton-like reactions at acid and neutral pH solutions, which can be attributed to its large porosity, high density of the photoactive triazine moiety, vertical π arrays formed by eclipsed layer stacking and the <i>β</i>‑ketoenamine linkage. Our experiments showed that the photocatalyst can absorb visible light effectively for activation of H<sub>2</sub>O<sub>2</sub>, producing abundant reactive oxygen species including superoxide radical (O<sub>2</sub><sup>·-</sup>), hydroxyl radical (<sup>·</sup>OH), and singlet oxygen (<sup>1</sup>O<sub>2</sub>) for oxidizing organic pollutants. This work not only provides an efficient metal-free photocatalyst for Fenton-like reactions, but also paves the way for COFs towards advanced oxidation processes, opening up the possibilities to their future applications in industry.

Transition-Metal-Free Radical Homocoupling Polymerization to Conjugated Poly(Phenylene butadiynylene) Polymers

2021 ◽  
Author(s):  
Qingmin Liu ◽  
Xuepeng Wang ◽  
Bien Tan ◽  
Shangbin Jin
Keyword(s):  
Free Radical ◽  
Heterogeneous Catalysis ◽  
Transition Metal ◽  
Gas Adsorption ◽  
Porous Polymers ◽  
Metal Free ◽  
Microporous Polymers ◽  
Conjugated Microporous Polymers

Conjugated microporous polymers (CMPs) are attractive porous polymers which have found enormous science and technical in-terests in gas adsorption and heterogeneous catalysis. However, most of these conjugated porous polymers are...

Melamine-derived graphitic carbon nitride as a new effective metal-free catalyst for Knoevenagel condensation of benzaldehyde with ethylcyanoacetate

2018 ◽  
Vol 8 (11) ◽  
pp. 2928-2937 ◽  
Author(s):  
N. D. Shcherban ◽  
P. Mäki-Arvela ◽  
A. Aho ◽  
S. A. Sergiienko ◽  
P. S. Yaremov ◽  
...  
Keyword(s):  
Carbon Nitride ◽  
Knoevenagel Condensation ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Metal Free

Melamine-derived C3N4 was tested in Knoevenagel condensation of benzaldehyde with ethylcyanoacetate.

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