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Sahari A, Puumi J, Mannisto JK, Repo T. Dual Nickel Photocatalysis for O-Aryl Carbamate Synthesis from Carbon Dioxide. J Org Chem 2023; 88:3822-3829. [PMID: 36848485 PMCID: PMC10028690 DOI: 10.1021/acs.joc.3c00023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
We report the use of dual nickel photocatalysis in the synthesis of O-aryl carbamates from aryl iodides or bromides, amines, and carbon dioxide. The reaction proceeded in visible light, at ambient carbon dioxide pressure, and without stoichiometric activating reagents. Mechanistic analysis is consistent with a Ni(I-III) cycle, where the active species is generated by the photocatalyst. The rate-limiting steps were the photocatalyst-mediated reduction of Ni(II) to Ni(I) and subsequent oxidative addition of the aryl halide. The physical properties of the photocatalyst were critical for promoting formation of O-aryl carbamates over various byproducts. Nine new phthalonitrile photocatalysts were synthesized, which exhibited properties that were vital to achieve high selectivity and activity.
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Affiliation(s)
- Aleksi Sahari
- Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Jukka Puumi
- Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Jere K Mannisto
- Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Timo Repo
- Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
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Kumar D, Singhal C, Yadav M, Joshi P, Patra P, Tanwar S, Das A, Kumar Pramanik S, Chaudhuri S. Colistin potentiation in multidrug-resistant Acinetobacter baumannii by a non-cytotoxic guanidine derivative of silver. Front Microbiol 2023; 13:1006604. [PMID: 36687622 PMCID: PMC9846554 DOI: 10.3389/fmicb.2022.1006604] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/23/2022] [Indexed: 01/06/2023] Open
Abstract
A novel nano-formulation (NF) that sensitizes Acinetobacter baumannii (AB) to otherwise ineffective colistin is described in the present study. Infections due to multidrug resistant (MDR) AB represent a major therapeutic challenge, especially in situations of pre-existing colistin resistance (colR). Subsequently, boosting the effectiveness of colistin would be a better alternative tactic to treat AB infections rather than discovering a new class of antibiotics. We have previously demonstrated an NF comprising self-assembled guanidinium and ionic silver nanoparticles [AD-L@Ag(0)] to have anti-biofilm and bactericidal activity. We report NF AD-L@Ag(0) for the very first time for the potentiation of colistin in Gram-negative colistin-resistant bacteria. Our results implied that a combination of clinically relevant concentrations of colistin and AD-L@Ag(0) significantly decreased colistin-resistant AB bacterial growth and viability, which otherwise was elevated in the presence of only colistin. In this study, we have described various combinations of minimum inhibitory concentration (MIC) of colistin (MICcol, 1/2 MICcol, and 1/4 MICcol) and that of AD-L@Ag(0) [MICAD-L@Ag(0), 1/2 MICAD-L@Ag(0), and 1/4 MICAD-L@Ag(0)] and tested them against MDR AB culture. The results (in broth as well as in solid media) signified that AD-L@Ag(0) was able to potentiate the anti-microbial activity of colistin at sub-MIC concentrations. Furthermore, the viability and metabolic activity of bacterial cells were also measured by CTC fluorescence assay and ATP bioluminescence assay. The results of these assays were in perfect concordance with the scores of cultures (colony forming unit and culture turbidity). In addition, quantitative real-time PCR (qRT-PCR) was performed to unveil the expression of selected genes, DNAgyrA, DNAgyrB, and dac. These genes introduce negative supercoiling in the DNA, and hence are important for basic cellular processes. These genes, due to mutation, modified the Lipid A of bacteria, further resisting the uptake of colistin. Therefore, the expression of these genes was upregulated when AB was treated with only colistin, substantiating that AB is resistant to colistin, whereas the combinations of MICcol + MICAD-L@Ag(0) downregulated the expression of these genes, implying that the developed formulation can potentiate the efficiency of colistin. In conclusion, AD-L@Ag(0) can potentiate the proficiency of colistin, further enhancing colistin-mediated death of AB by putatively disrupting the outer membrane (OM) and facilitating bacterial death.
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Affiliation(s)
- Deepak Kumar
- Translational Health Science and Technology Institute (THSTI), Faridabad, India
| | - Chaitali Singhal
- Translational Health Science and Technology Institute (THSTI), Faridabad, India
| | - Manisha Yadav
- Translational Health Science and Technology Institute (THSTI), Faridabad, India
| | - Pooja Joshi
- Translational Health Science and Technology Institute (THSTI), Faridabad, India
| | - Priyanka Patra
- CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India
| | - Subhash Tanwar
- Translational Health Science and Technology Institute (THSTI), Faridabad, India
| | - Amitava Das
- Indian Institute of Science Education and Research Kolkata, Mohanpur, India,*Correspondence: Amitava Dasc,
| | - Sumit Kumar Pramanik
- CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India,Sumit Kumar Pramanikb,
| | - Susmita Chaudhuri
- Translational Health Science and Technology Institute (THSTI), Faridabad, India,Susmita Chaudhuria,
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Dey A, Yadav M, Kumar D, Dey AK, Samal S, Tanwar S, Sarkar D, Pramanik SK, Chaudhuri S, Das A. A combination therapy strategy for treating antibiotic resistant biofilm infection using a guanidinium derivative and nanoparticulate Ag(0) derived hybrid gel conjugate. Chem Sci 2022; 13:10103-10118. [PMID: 36128224 PMCID: PMC9430544 DOI: 10.1039/d2sc02980d] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/22/2022] [Indexed: 11/25/2022] Open
Abstract
Bacteria organized in biofilms show significant tolerance to conventional antibiotics compared to their planktonic counterparts and form the basis for chronic infections. Biofilms are composites of different types of extracellular polymeric substances that help in resisting several host-defense measures, including phagocytosis. These are increasingly being recognized as a passive virulence factor that enables many infectious diseases to proliferate and an essential contributing facet to anti-microbial resistance. Thus, inhibition and dispersion of biofilms are linked to addressing the issues associated with therapeutic challenges imposed by biofilms. This report is to address this complex issue using a self-assembled guanidinium-Ag(0) nanoparticle (AD-L@Ag(0)) hybrid gel composite for executing a combination therapy strategy for six difficult to treat biofilm-forming and multidrug-resistant bacteria. Improved efficacy was achieved primarily through effective biofilm inhibition and dispersion by the cationic guanidinium ion derivative, while Ag(0) contributes to the subsequent bactericidal activity on planktonic bacteria. Minimum Inhibitory Concentration (MIC) of the AD-L@Ag(0) formulation was tested against Acinetobacter baumannii (25 μg mL-1), Pseudomonas aeruginosa (0.78 μg mL-1), Staphylococcus aureus (0.19 μg mL-1), Klebsiella pneumoniae (0.78 μg mL-1), Escherichia coli (clinical isolate (6.25 μg mL-1)), Klebsiella pneumoniae (clinical isolate (50 μg mL-1)), Shigella flexneri (clinical isolate (0.39 μg mL-1)) and Streptococcus pneumoniae (6.25 μg mL-1). Minimum bactericidal concentration, and MBIC50 and MBIC90 (Minimum Biofilm Inhibitory Concentration at 50% and 90% reduction, respectively) were evaluated for these pathogens. All these results confirmed the efficacy of the formulation AD-L@Ag(0). Minimum Biofilm Eradication Concentration (MBEC) for the respective pathogens was examined by following the exopolysaccharide quantification method to establish its potency in inhibition of biofilm formation, as well as eradication of mature biofilms. These effects were attributed to the bactericidal effect of AD-L@Ag(0) on biofilm mass-associated bacteria. The observed efficacy of this non-cytotoxic therapeutic combination (AD-L@Ag(0)) was found to be better than that reported in the existing literature for treating extremely drug-resistant bacterial strains, as well as for reducing the bacterial infection load at a surgical site in a small animal BALB/c model. Thus, AD-L@Ag(0) could be a promising candidate for anti-microbial coatings on surgical instruments, wound dressing, tissue engineering, and medical implants.
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Affiliation(s)
- Ananta Dey
- CSIR - Central Salt and Marine Chemical Research Institute Bhavnagar Gujarat India
- Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
| | - Manisha Yadav
- Translational Health Science and Technology Institute (THSTI) Faridabad 121001 Haryana India
| | - Deepak Kumar
- Translational Health Science and Technology Institute (THSTI) Faridabad 121001 Haryana India
| | - Anik Kumar Dey
- CSIR - Central Salt and Marine Chemical Research Institute Bhavnagar Gujarat India
| | - Sweety Samal
- Translational Health Science and Technology Institute (THSTI) Faridabad 121001 Haryana India
| | - Subhash Tanwar
- Translational Health Science and Technology Institute (THSTI) Faridabad 121001 Haryana India
| | - Debrupa Sarkar
- Translational Health Science and Technology Institute (THSTI) Faridabad 121001 Haryana India
| | - Sumit Kumar Pramanik
- CSIR - Central Salt and Marine Chemical Research Institute Bhavnagar Gujarat India
| | - Susmita Chaudhuri
- Translational Health Science and Technology Institute (THSTI) Faridabad 121001 Haryana India
| | - Amitava Das
- Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
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Effects of Simulated Solar Wind on Polymethyl Methacrylate Thin Film. NANOMATERIALS 2022; 12:nano12121992. [PMID: 35745331 PMCID: PMC9229547 DOI: 10.3390/nano12121992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/07/2022] [Accepted: 06/07/2022] [Indexed: 12/04/2022]
Abstract
Space exploration missions are currently becoming more frequent, due to the ambition for space colonization in sight of strengthening terrestrial technologies and extracting new raw materials and/or resources. In this field, the study of the materials’ behaviour when exposed to space conditions is fundamental for enabling the use of currently existing materials or the development of new materials suitable for application in extra-terrestrial environments. In particular, the versatility of polymers renders them suitable for advanced applications, but the effects of space radiation on these materials are not yet fully understood. Here, to shed light on the effects of simulated solar wind on a polymeric material, polymethyl methacrylate (PMMA) was produced through radical bulk polymerization. The PMMA in the form of a thin film was subjected to proton beam bombardment at different fluences and in a high vacuum environment, with structural changes monitored through real-time FT-IR analysis. The structure of the residual material was investigated through MALDI-TOF mass spectrometry and 1H-NMR spectroscopy. The collected data allowed us to hypothesize the structural modifications of the PMMA and the related mechanisms.
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Santos MRE, Mendonça PV, Branco R, Sousa R, Dias C, Serra AC, Fernandes JR, Magalhães FD, Morais PV, Coelho JFJ. Light-Activated Antimicrobial Surfaces Using Industrial Varnish Formulations to Mitigate the Incidence of Nosocomial Infections. ACS APPLIED MATERIALS & INTERFACES 2021; 13:7567-7579. [PMID: 33538168 DOI: 10.1021/acsami.0c18930] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Evidence has shown that hospital surfaces are one of the major vehicles of nosocomial infections caused by drug-resistant pathogens. Smart surface coatings presenting multiple antimicrobial activity mechanisms have emerged as an advanced approach to safely prevent this type of infection. In this work, industrial waterborne polyurethane varnish formulations containing for the first time cationic polymeric biocides (SPBs) combined with photosensitizer curcumin were developed to afford contact-active and light-responsive antimicrobial surfaces. SPBs were prepared by atom transfer radical polymerization, which allows control over the polymer features that influence antimicrobial efficiency (e.g., molecular weight), while natural curcumin was employed to impart photodynamic activity to the surface. Antibacterial testing against Gram-negative Escherichia coli revealed that glass surfaces coated with the new formulations displayed photokilling effect under white-light (42 mW/cm2) irradiation within only 15 min of exposure. In addition, it was observed a combined antimicrobial effect between the two biocides (cationic SPB and curcumin), with a higher reduction in the number of viable bacteria observed for the surfaces containing cationic SPB/curcumin mixtures in comparison with the one obtained for surfaces only with polymer or without biocides. The waterborne industrial varnish formulations allowed the formation of homogeneous films without the need for addition of a coalescing agent, which can be potentially applied in diverse surface substrates to reduce bacterial transmission infections in healthcare environments.
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Affiliation(s)
- Madson R E Santos
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - Patrícia V Mendonça
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - Rita Branco
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Ruben Sousa
- LEPABE Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Carla Dias
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - Arménio C Serra
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
| | - José R Fernandes
- Centre for Chemistry, Vila Real (CQVR), Physics Department, School of Science and Technology (ECT), University of Trás-dos-Montes e Alto Douro, 5000-801 Vila Real, Portugal
| | - Fernão D Magalhães
- LEPABE Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Paula V Morais
- Centre for Mechanical Engineering, Materials and Processes, Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal
| | - Jorge F J Coelho
- Centre for Mechanical Engineering, Materials and Processes, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima-Polo II, 3030-790 Coimbra, Portugal
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Flejszar M, Chmielarz P, Wolski K, Grześ G, Zapotoczny S. Polymer Brushes via Surface-Initiated Electrochemically Mediated ATRP: Role of a Sacrificial Initiator in Polymerization of Acrylates on Silicon Substrates. MATERIALS 2020; 13:ma13163559. [PMID: 32806681 PMCID: PMC7475859 DOI: 10.3390/ma13163559] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/08/2020] [Accepted: 08/10/2020] [Indexed: 01/05/2023]
Abstract
Silicon wafers as semiconductors are essential components of integrated circuits in electronic devices. For this reason, modification of the silicon surface is an important factor in the manufacturing of new hybrid materials applied in micro- and nanoelectronics. Herein, copolymer brushes of hydrophilic poly(2-hydroxyethyl acrylate) (PHEA) and hydrophobic poly(tert-butyl acrylate) (PtBA) were grafted from silicon wafers via simplified electrochemically mediated atom transfer radical polymerization (seATRP) according to a surface-initiated approach. The syntheses of PHEA-b-PtBA copolymers were carried out with diminished catalytic complex concentration (successively 25 and 6 ppm of Cu). In order to optimize the reaction condition, the effect of the addition of a supporting electrolyte was investigated. A controlled increase in PHEA brush thickness was confirmed by atomic force microscopy (AFM). Various other parameters including contact angles and free surface energy (FSE) for the modified silicon wafer were presented. Furthermore, the effect of the presence of a sacrificial initiator in solution on the thickness of the grafted brushes was reported. Successfully fabricated inorganic–organic hybrid nanomaterials show potential application in biomedicine and microelectronics devices, e.g., biosensors.
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Affiliation(s)
- Monika Flejszar
- Department of Physical Chemistry, Faculty of Chemistry, Rzeszow University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland;
| | - Paweł Chmielarz
- Department of Physical Chemistry, Faculty of Chemistry, Rzeszow University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland;
- Correspondence: ; Tel.: +48-17-865-1809
| | - Karol Wolski
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland; (K.W.); (G.G.); (S.Z.)
| | - Gabriela Grześ
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland; (K.W.); (G.G.); (S.Z.)
| | - Szczepan Zapotoczny
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland; (K.W.); (G.G.); (S.Z.)
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