| 1. |
- Hamidi, Hassan, et al.
(author)
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Photocurrent Generation from Thylakoid Membranes on Osmium-Redox-Polymer-Modified Electrodes.
- 2015
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In: ChemSusChem. - : Wiley. - 1864-564X .- 1864-5631. ; 8:6, s. 990-993
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Journal article (peer-reviewed)abstract
- Thylakoid membranes (TMs) are uniquely suited for photosynthesis owing to their distinctive structure and composition. Substantial efforts have been directed towards use of isolated photosynthetic reaction centers (PRCs) for solar energy harvesting, however, few studies investigate the communication between whole TMs and electrode surfaces, due to their complex structure. Here we report on a promising approach to generate photosynthesis-derived bioelectricity upon illumination of TMs wired with an osmium-redox-polymer modified graphite electrode, and generate a photocurrent density of 42.4 μA cm(-2) .
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| 2. |
- Hasan, Badrul, et al.
(author)
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Fecal carriage of multi-drug resistant and extended spectrum beta-lactamases producing E. coli in household pigeons, Bangladesh
- 2014
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In: Veterinary Microbiology. - : Elsevier BV. - 0378-1135 .- 1873-2542. ; 168:1, s. 221-224
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Journal article (peer-reviewed)abstract
- Antibiotic resistance and ESBL constitute a risk to human and animal health. Birds residing close to humans could mirror the spectrum of human associated antibiotic resistance. Household pigeons were screened in Bangladesh to shed light on human associated, as well as, environmental antibiotic resistance. Escherichia coil from pigeons (n = 150) were tested against 11 antibiotics. 89% E. coil isolates were resistant to one or more critically important human antibiotics like ampicillin, cefadroxil, mecillinam, ciprofloxacin, gentamicin and tigecycline. No carbapenamase-producers were detected and the lower ESBL prevalence (5%) in pigeons. ESBL-producing E. coil isolates had bla(CTX-M_15) genes. Pigeons shared some bacterial clones and had bird associated sequence types like E. coil ST1408. Fecal carriage of bacteria resistance of critically important human antibiotics, together with examples of shared genotypes among pigeons, indicate the human-birds and bird to bird transmissions are important in the epidemiology of antibiotic resistance.
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| 3. |
- Hasan, Kamrul, et al.
(author)
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Electrochemical Communication Between Electrodes and Rhodobacter capsulatus Grown in Different Metabolic Modes
- 2015
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In: Electroanalysis. - : Wiley. - 1040-0397. ; 27:1, s. 118-127
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Journal article (peer-reviewed)abstract
- The majority of efforts on microbial and photosynthetic microbial fuel cells are both curiosity driven and made to possibly meet the future growing demand for sustainable energy. The most metabolically versatile purple bacteria Rhodobacter capsulatus is a potential candidate for this purpose. However, utilizing bacteria in such systems requires efficient electronic transfer communication between the microbial cells and the electrodes, which is one of the greatest challenges. Previous studies demonstrated that osmium redox polymers (ORPs) could be used for extracellular electron transfer between the cells and electrodes. Recently, heterotrophically grown R. capsulatus has been wired with ORP modified electrodes. Here in this communication, we report electron transfer from R. capsulatus grown under heterotrophic as well as under photoheterotrophic conditions to electrodes. The cells, immobilized on bare graphite and ORP modified graphite electrodes, were excited with visible light and subsequent photosynthetic electron transfer was recorded using cyclic voltammetric and chronoamperometric measurements. Photoheterotrophically grown R. capsulatus cells on bare graphite generate a significant photocurrent density of 3.46 mu A cm(-2), whereas on an ORP modified electrode the current density increases to 8.46 mu A cm(-2). Furthermore, when 1 mM p-benzoquinone is added to the electrolyte the photocurrent density reaches 12.25 mu A cm(-2). Our results could have significant implications in photosynthetic energy conversion and in development of photobioelectrochemical devices.
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| 4. |
- Hasan, Kamrul, et al.
(author)
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Electrochemical communication between heterotrophically grown Rhodobacter capsulatus with electrodes mediated by an osmium redox polymer.
- 2013
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In: Bioelectrochemistry. - : Elsevier BV. - 1878-562X .- 1567-5394. ; 93:Online 15 June 2012, s. 30-36
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Journal article (peer-reviewed)abstract
- The metabolically versatile purple bacteria Rhodobacter capsulatus was investigated to check its possible applicability in biofuel cells and electrochemical microbial biosensors. The wild type strain ATCC 17015 and mutant strain 37b4 lacking the lipopolysaccharide capsule was compared for their ability to communicate with electrodes modified with an osmium redox polymer. In this work, aerobic heterotrophically grown R. capsulatus were used to screen for efficient cell-electrode communication for later implementation using photoheterotrophically grown bacteria. The bacterial cells embedded in the osmium polymer matrix demonstrated efficient electrical "wiring" with the electrodes and were able to generate a noticeable current with succinate as substrate. Interestingly, at 2mM succinate the wild type strain showed much better bioelectrocatalytic current generation (4.25μA/cm(2)) than the strain lacking capsule (1.55μA/cm(2)). The wild type strain also exhibited a stable current response for longer time, demonstrating that the bacterial lipopolysaccharide in fact enhances the stability of the polymer matrix layer of the modified electrode. Control experiments with R. capsulatus without any mediator did not show any current irrespective of the capsule presence. This demonstrates that development of photosensors and other light driven bioelectrochemical devices could be feasible using R. capsulatus and will be at focus for future studies.
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| 5. |
- Hasan, Kamrul, et al.
(author)
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Electrochemical communication between microbial cells and electrodes via osmium redox systems.
- 2012
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In: Biochemical Society Transactions. - 0300-5127. ; 40:6, s. 1330-1335
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Journal article (peer-reviewed)abstract
- Electrochemical communication between micro-organisms and electrodes is the integral and fundamental part of BESs (bioelectrochemical systems). The immobilization of bacterial cells on the electrode and ensuring efficient electron transfer to the electrode via a mediator are decisive features of mediated electrochemical biosensors. Notably, mediator-based systems are essential to extract electrons from the non-exoelectrogens, a major group of microbes in Nature. The advantage of using polymeric mediators over diffusible mediators led to the design of osmium redox polymers. Their successful use in enzyme-based biosensors and BFCs (biofuel cells) paved the way for exploring their use in microbial BESs. The present mini-review focuses on osmium-bound redox systems used to date in microbial BESs and their role in shuttling electrons from viable microbial cells to electrodes.
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| 6. |
- Hasan, Kamrul, et al.
(author)
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Evaluation of Photocurrent Generation from Different Photosynthetic Organisms
- 2017
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In: ChemElectroChem. - : Wiley. - 2196-0216. ; 4:2, s. 412-417
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Journal article (peer-reviewed)abstract
- Biological photovoltaics (BPVs) are emerging as a potential sustainable energy-generating technology to convert solar energy into electrical energy. Although a great variety of photosynthetic biomaterials were studied in BPVs, cyanobacteria are considered as superior candidates because of their simpler physiology. To facilitate extracellular electron transfer (EET) from cyanobacteria to electrodes is the greatest challenge to improving the performance of BPVs. However, a systematic study comparing the photo-excited EET from such organisms is not yet reported. Here we report on a comparison of photocurrent density generated by benthic cyanobacteria, that is, two species of Leptolyngbya sp. (CAWBG62 and CAWBG100), one species from the order Chroococcales (CAWBG64), and a eukaryotic algae, Paulschulzia pseudovolvox (UKE). This algae and CAWBG100 were sourced from New Zealand, CAWBG62 and CAWBG64 were from Antarctica. We demonstrate EET mediated by three different electron transfer (ET) mediating systems on graphite electrodes. These are as follows: (I) [Os(2,2’-(bipyridine)2(polyvinyl-imidazole)10Cl]+/2+ (1:9) [Os-(bpy)PVI] (II) p-benzoquinone (PBQ) (III) [Os-(bpy)PVI] together with PBQ. The maximum photocurrent density of 47.2 μA cm−2 was obtained from CAWBG64 mediated by (III) [Os-(bpy)PVI] together with PBQ.
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| 7. |
- Hasan, Kamrul
(author)
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Microbial Electrochemical System: extracellular electron transfer from photosynthesis and respiration to electrode
- 2016
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Doctoral thesis (other academic/artistic)abstract
- The electrochemical communication between microorganisms and electrodes has substantial implications both for basic understanding of biological electron transfer as well as in diverse applications, such as, microbial electrochemical system (MES), microbial biosensors and in production of valuable chemicals. In these systems the extracellular electron transfer (EET) from microbial metabolism to electrodes is restricted due to the insulated cellular exterior made of lipid structures. To obtain the electrochemical wiring of biomaterials with electrodes, osmium redox polymers (ORPs) was used as an efficient electron transfer (ET) mediator. In this thesis a systematic study on EET from a variety of biomaterials is demonstrated. The EET from the most metabolically versatile purple bacterium, i.e., Rhodobacter capsulatus, grown under both heterotrophically and photoheterotrophically conditions was studied. Shewanella oneidensis MR-1 is a metal ion reducing bacterium and was highly studied in microbial electrochemical systems (MES) due to its direct ET competence. We have shown that S. oneidensis MR-1 can be coupled with ORP modified graphite electrodes that results in an enhanced current density. A secured supply of cost effective sustainable energy is on of the greatest challenges in the 21st century. Biological photovoltaics (BPVs) is emerging as a potential energy generating technology to convert solar energy into electrical energy. To harness solar energy we studied the photo-excited EET from water oxidation via thylakoid membranes, the site of photosynthesis in green plants and algae. In addition three prokaryotic cyanobacteria, two different Leptolyngbya sp., and Chroococcales sp. were photo-electrochemically wired with electrodes. The photo-electrochemical communication of a multicellular eukaryotic alga was assumed to be challenging, since here photosynthesis occurs in a specially designed subcellular organelle called chloroplast. We have shown the photoelectrochemical communication of the eukaryotic alga, Paulschulzia pseudovolvox immobilized on a graphite electrode wired with ORPs. Although a great deal of research is focussed on MES, however, to seek any potential practical application their performance due the low power output and restricted stability need to be improved many folds. Our findings could have substantial implications in MES, such as microbial fuel cells (MFC), microbial biosensors, photosynthetic energy generation and in other light sensitive bioelectrochemical devices.
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| 8. |
- Hasan, Kamrul, et al.
(author)
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Photo-electrochemical communication between cyanobacteria (Leptolyngbia sp.) and osmium redox polymer modified electrodes.
- 2014
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In: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084. ; 16:45, s. 24676-24680
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Journal article (peer-reviewed)abstract
- Photosynthetic microbial fuel cells (PMFCs) are an emerging technology for renewable solar energy conversion. Major efforts have been made to explore the electrogenic activity of cyanobacteria, mostly using practically unsustainable reagents. Here we report on photocurrent generation (≈8.64 μA cm(-2)) from cyanobacteria immobilized on electrodes modified with an efficient electron mediator, an Os(2+/3+) redox polymer. Upon addition of ferricyanide to the electrolyte, cyanobacteria generate the maximum current density of ≈48.2 μA cm(-2).
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| 9. |
- Hasan, Kamrul, et al.
(author)
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Photoelectrochemical Communication between Thylakoid Membranes and Gold Electrodes through Different Quinone Derivatives
- 2014
-
In: ChemElectroChem. - : Wiley. - 2196-0216. ; 1:1, s. 131-139
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Journal article (peer-reviewed)abstract
- Photosynthesis is a sustainable process for the conversion of light energy into chemical energy. Thylakoids in energy-transducing photosynthetic membranes are unique in biological membranes because of their distinguished structure and composition. The quantum trapping efficiency of thylakoid membranes is appealing in photobioelectrochemical research. In this study, thylakoid membranes extracted from spinach are shown to communicate with a gold-nanoparticle-modified solid gold electrode (AuNP-Au) through a series of quinone derivatives. Among these, para-benzoquinone (PBQ) is found to be the best soluble electron-transfer mediator, generating the highest photocurrent of approximately 130 mu Acm(-2) from water oxidation under illumination. In addition, the photocurrent density is investigated as a function of applied potential, the effect of light intensity, quinone concentration, and amount of thylakoid membrane. Finally, the source of photocurrent is confirmed by using 3-(3,4-dichlorophenyl)-1,1-dimethylurea (known by its trade name, Diuron), an inhibitor of photosystem II, which decreases the total photocurrent by 50%.
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| 10. |
- Hasan, Kamrul, et al.
(author)
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Photoelectrochemical Wiring of Paulschulzia pseudovolvox (Algae) to Osmium Polymer Modified Electrodes for Harnessing Solar Energy
- 2015
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In: Advanced Energy Materials. - : Wiley. - 1614-6832. ; 5:22
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Journal article (peer-reviewed)abstract
- Studies on biological photovoltaics based on intact organisms are challenging and in most cases include diffusing mediators to facilitate electrochemical communication with electrodes. However, using such mediators is impractical. Instead, surface confined Os-polymers have been successfully used in electrochemical studies including oxidoreductases and bacterial cells but not with algae. Photoelectrogenic activity of a green alga, Paulschulzia pseudovolvox, immobilized on graphite or Os-polymer modified graphite is demonstrated. Direct electron transfer is revealed, when no mediator is added, between algae and electrodes with electrons emerging from photolysis of water via the cells to the electrode exhibiting a photocurrent density of 0.02 mu A cm(-2). Os-polymers with different redox potentials and structures are used to optimize the energy gap between the photosynthetic complexes of the cells and the Os-polymers and those of greater solubility, better accessibility with membranes, and relatively higher potentials yielded a photocurrent density of 0.44 mu A cm(-2). When benzoquinone is included to the electrolyte, the photocurrent density reaches 6.97 mu A cm(-2). The photocurrent density is improved to 11.50 mu A cm(-2), when the cells are protected from reactive oxygen species when either superoxide dismutase or catalase is added. When adding an inhibitor specific for photosystem II, diuron, the photocurrent is decreased by 50%.
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