Significance and potential of marine microbial natural bioactive compounds against biofilms/biofouling: necessity for green chemistry

Natural products from the unique environments of sea water and oceans represent a largely unfamiliar source for isolation of new microbes, which are potent producers of secondary bioactive metabolites. These unique life-forms from the marine ecosphere have served as an important source of drugs since ancient times and still offer a valuable resource for novel findings by providing remedial treatments. Therefore, it can be expected that many naturally bioactive marine microbial compounds with novel structures and bioactivities against those from terrestrial environments may be found among marine metabolites. Biofilms in aquatic environment possess serious problems to naval forces and oceanic industries around the globe. Current anti-biofilm or anti-biofouling technology is based on the use of toxic substances that can be harmful to their surrounding natural locales. Comprehensive research has been done to examine the bioactive potential of marine microbes. Results are remarkably varied and dynamic, but there is an urgent need for bioactive compounds with environmentally friendly or “green” chemical activities. Marine microbes have the potential as upcoming and promising source of non-toxic compounds with sustainable anti-biofouling/anti-biofilm properties as they can produce substances that can inhibit not only the chemical components required for biofilm production but also the attachment, microorganism growth, and/or cell–cell communication

Influence of hydrogen bonding on electrochromic properties of conducting polymers

4,7-Bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-phenyl-1H-benzo[d]imidazole (BImBEd) was synthesized via Stille coupling reaction of 4,7-dibromo-2-phenyl-1H-benzo[d]imidazole (BImB) with monostannylated 3,4-ethylenedioxythiophene (EDOT). In order to figure out the presence of an intramolecular hydrogen bonding between the amine bond of the imidazole ring and the oxygen of the EDOT molecule, different amounts of trifluoroacetic acid (TFA) and concentrated sodium hydroxide (NaOH) solutions were added during electrochemical polymerization. These treatments caused protonation of the imine and deprotonation of the amine bonds respectively. In order to prove the changes in the optical properties of the polymers due to different number of protonated and deprotonated imine and amine bonds, 1,4-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)benzene (BEDOT-B) was also synthesized. Results showed that it is possible to control the main chain conformation of even an insoluble polymer via acid and base treatments during in situ polymerization

Non-toxic, non-biocide-release antifouling coatings based on molecular structure design for marine applications

Marine biofouling generally refers to the undesirable accumulation of biological organisms on surfaces in contact with seawater. This natural phenomenon represents a major economic concern for marine industries, e.g. for ships and vessels, oil and wind-turbine sea-platforms, pipelines, water valves and filters, as it limits the performance of devices, materials and underwater structures and increases the costs related to transport delays, hull maintenance and repair, cleaning and desalination units, corrosion and structure break-down. In the last few decades, many efforts have been spent into developing efficient antifouling (AF) surfaces (coatings) combining advances in materials science and recent knowledge of marine chemistry and biology. However, the extensive use of toxic and harmful compounds in the formulations raised increasing health and environmental concerns leading to stricter regulations which pushed marine industries to search for new AF strategies. This review presents the recent research progress made in green strategies for AF coatings using non-toxic, non-biocide-release based principles for marine applications. The two main approaches, detachment of biofoulants or preventing biofoulants attachment, are reviewed in detail and new promising routes based on amphiphilic, (super)hydrophilic, and topographic (structured) surfaces are highlighted. The chemical and physical aspects of the AF mechanisms behind the AF strategies reviewed are emphasized, with special attention to the early stages of biofoulant adhesion, keeping the focus on the materials' molecular structure and properties which allow obtaining the final desired antifouling behaviour

Multichromic benzimidazole-containing polymers: Comparison of donor and acceptor unit effects

This study reports a comparative study on electrochromic properties of two donoracceptordonor (DAD)-type polymers namely poly(2-heptyl-4,7-di(thiophen-2-yl)-1H-benzo [d]imidazole) (BImTh) and poly(4,7-bis(2,3-dihydrothieno[3,4-b] [1,4]dioxin-5-yl)-2-heptyl-1H-benzo[d]imidazole) (BImEd). DAD-type monomers were polymerized electrochemically on indium tin oxide-coated glass slides to determine the optical properties of the polymers. Electrochemical rho-doping experiments were performed to determine the band gap and absorption band values of the polymer films at different redox states. Polymerization of BImTh and BImEd yields multichromic polymers. Donor and acceptor effects are studied by comparing the PBImEd and PBImTh with corresponding benzotriazole derivatives. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 201

Synthesis and electrochromic properties of trans-stilbene bearing copolymers obtained with different repeat unit and chain length

Three new random copolymers containing benzotriazole (BTz), thiophene (Th) and trans-stilbene (St) were synthesized via Stille coupling technique with different monomer ratios. In order to determine the effect of stilbene quantity on electrochromic properties of the polymers, feed ratios of the monomers were altered in chemical polymerization. Polymer chain length effect was also investigated via using different reaction times and the same feed ratio. The characteristics of the synthesized copolymers were compared based on their quantity of stilbene moiety and chain length. Redox potentials and HOMO/LUMO energy levels of all polymers were characterized by cyclic voltammetry. To evaluate the optical properties of the electrochromic copolymers, spectroelectrochemistry technique was used. Optical band gap values of the copolymers were found in the range between 1.85 and 2.06 eV. Optical contrasts and switching ability of the polymer films were determined by square wave chronoamperometry. Solution processable polymers reveal multichromicity upon oxidation and reduction at low potentials, fast switching times and low band gap

A novel conducting copolymer: Investigation of its matrix properties for cholesterol biosensor applications

2-Heptyl-4,7-di(thiophen-2-yl)-1H-benzo[d]imidazole) (BImTh) was synthesized. Electrochemical copolymerization of this monomer with 2-(((9H-fluoren-9-yl)methoxy)carbonylamino)acetic acid (Fmoc-Gly-OH) was achieved on a graphite electrode and used as a matrix for amperometric cholesterol biosensing studies. In order to prepare a new cholesterol biosensor, cholesterol oxidase (ChOx) was covalently immobilized onto the copolymer coated graphite electrode. Cholesterol was used as the substrate and the decrease in oxygen level as a result of enzymatic reaction was monitored at -0.7V vs Ag reference electrode in a phosphate buffer (50 mM, pH 7.0). Kinetic parameters, storage stabilities and surface characteristics were investigated. K-M(app), I-max, LOD and sensitivity were calculated as 6.25 mu M, 9.69 mu A, 0.17 mu M and 2.47 mA/mM cm(2), respectively. This biosensor was applied to the determination of total cholesterol in serum samples. The estimation of cholesterol is an important for the diagnosis and prevention of several heart diseases and arteriosclerosis. Hence, it is important to develop new cholesterol biosensors

A novel conducting copolymer: Investigation of its matrix properties for cholesterol biosensor applications

2-Heptyl-4,7-di(thiophen-2-yl)-1H-benzo[d]imidazole) (BImTh) was synthesized. Electrochemical copolymerization of this monomer with 2-(((9H-fluoren-9-yl)methoxy)carbonylamino)acetic acid (Fmoc-Gly-OH) was achieved on a graphite electrode and used as a matrix for amperometric cholesterol biosensing studies. In order to prepare a new cholesterol biosensor, cholesterol oxidase (ChOx) was covalently immobilized onto the copolymer coated graphite electrode. Cholesterol was used as the substrate and the decrease in oxygen level as a result of enzymatic reaction was monitored at -0.7V vs Ag reference electrode in a phosphate buffer (50 mM, pH 7.0). Kinetic parameters, storage stabilities and surface characteristics were investigated. K-M(app), I-max, LOD and sensitivity were calculated as 6.25 mu M, 9.69 mu A, 0.17 mu M and 2.47 mA/mM cm(2), respectively. This biosensor was applied to the determination of total cholesterol in serum samples. The estimation of cholesterol is an important for the diagnosis and prevention of several heart diseases and arteriosclerosis. Hence, it is important to develop new cholesterol biosensors

Further investigation of intramolecular H-bonding in benzimidazole and EDOT containing monomer

Density functional theory (OFT) calculations of the relative stabilities and harmonic vibrational spectra of four different conformers of 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-phenyl-1H-benzo[d] imidazole (BlmBEd) are presented and compared with experimental IR data. BlmBEd, containing phenyl substituted benzimidazole as the acceptor and 3,4-ethylenedioxythiophene (EDOT) as the donor unit, was electrochemically polymerized in different pH media earlier. Electronic states of nitrogen in benzimidazole unit of synthesized polymeric films were analyzed via X-ray photoelectron spectroscopy. Both DFT and XPS results suggest the presence of an intramolecular H-bond between the amine of the imidazole and the oxygen of the EDOT molecules. Additionally, the quantity of the H-bond can be controlled via treatment of an acid (trifloroacetic acid) and a base (sodium hydroxide) as we stated in our previous study

Syntheses, electrochemical and photophysical properties of biphenyl containing conjugated copolymers

Poly 4-(biphenyl-4-yl)-4'-tert butylspiro[benzo[d]imidazole-2,1'-cyclohexane] (P1), Poly 4-(biphenyl-4-yl)2-dodecyl-2H-benzo[d][1,2,3]triazole (P2), Poly(4-(5-(biphenyl-4-yl)-4-hexylthiophen-2-yl)-2-dodecyl-7(4-hexylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole (P3) were synthesized via Suzuki cross coupling polycondensation reaction. Polymers are thermally stable with decomposition temperatures above 300 C. Electrochemical and optical studies revealed that P2 and P3 exhibit reversible redox behavior with multichromic properties. Polymers showed highly fluorescent properties both in thin film and solution forms. Photoluminescence quantum efficiencies of P2 and P3 are 0.70 and 0.57 in chloroform respectively