Identification of Microorganisms that Bind Specifically to Target Materials of Interest Using a Magnetophoretic Microfluidic Platform.

Discovery of microorganisms and their relevant surface peptides that specifically bind to target materials of interest can be achieved through iterative biopanning-based screening of cellular libraries having high diversity. Recently, microfluidics-based biopanning methods have been developed and exploited to overcome the limitations of conventional methods where controlling the shear stress applied to remove cells that do not bind or only weakly bind to target surfaces is difficult and the overall experimental procedure is labor-intensive. Despite the advantages of such microfluidic methods and successful demonstration of their utility, these methods still require several rounds of iterative biopanning.

Aspergillus oryzae-Saccharomyces cerevisiae Consortium Allows Bio-Hybrid Fuel Cell to Run on Complex Carbohydrates.

Consortia of Aspergillus oryzae and Saccharomyces cerevisiae are examined for their abilities to turn complex carbohydrates into ethanol. To understand the interactions between microorganisms in consortia, Fourier-transform infrared spectroscopy is used to follow the concentrations of various metabolites such as sugars (e.g.

Simple, fast, and accurate methodology for quantitative analysis using Fourier transform infrared spectroscopy, with bio-hybrid fuel cell examples.

The standard methodologies for quantitative analysis (QA) of mixtures using Fourier transform infrared (FTIR) instruments have evolved until they are now more complicated than necessary for many users' purposes. We present a simpler methodology, suitable for widespread adoption of FTIR QA as a standard laboratory technique across disciplines by occasional users.•Algorithm is straightforward and intuitive, yet it is also fast, accurate, and robust.

Conjugated gold nanoparticles as a tool for probing the bacterial cell envelope: The case of Shewanella oneidensis MR-1.

The bacterial cell envelope forms the interface between the interior of the cell and the outer world and is, thus, the means of communication with the environment. In particular, the outer cell surface mediates the adhesion of bacteria to the surface, the first step in biofilm formation. While a number of ligand-based interactions are known for the attachment process in commensal organisms and, as a result, opportunistic pathogens, the process of nonspecific attachment is thought to be mediated by colloidal, physiochemical, interactions.

Effect of Modified Phospholipid Bilayers on the Electrochemical Activity of a Membrane-Spanning Conjugated Oligoelectrolyte.

The incorporation and electrochemical activity of a conjugated oligoelectrolyte (COE) in model phospholipid bilayers have been characterized using cyclic voltammetry and UV-vis absorption measurements. Several other modifiers were also incorporated into the phospholipid membranes to alter properties such as charge and alkyl chain disorder. Using potassium ferricyanide to measure charge transport, it was observed that bilayers that contained cholic acid, a negatively charged additive that also promotes alkyl chain disorder, had higher COE uptake and charge permeability than unmodified bilayers.

Photoelectrochemistry of photosystem I bound in nafion.

Developing a solid state Photosystem I (PSI) modified electrode is attractive for photoelectrochemical applications because of the quantum yield of PSI, which approaches unity in the visible spectrum. Electrodes are constructed using a Nafion film to encapsulate PSI as well as the hole-scavenging redox mediator Os(bpy)2Cl2. The photoactive electrodes generate photocurrents of 4 μA/cm(2) when illuminated with 1.

The conjugated oligoelectrolyte DSSN+ enables exceptional coulombic efficiency via direct electron transfer for anode-respiring Shewanella oneidensis MR-1-a mechanistic study.

Shewanella oneidensis MR-1 was cultivated on lactate with poised graphite electrode acceptors (E = +0.2 V vs. Ag/AgCl) in order to explore the basis for sustained increases in anodic current output following the addition of the lipid-intercalating conjugated oligoelectrolyte (COE), 4,4'-bis(4'-(N,N-bis(6''-(N,N,N-trimethylammonium)hexyl)amino)-styryl)stilbene tetraiodide (DSSN+).

Comparative photoactivity and stability of isolated cyanobacterial monomeric and trimeric Photosystem I.

Photoactivity of native trimeric, and non-native monomeric Photosystem I (PSI) extracted from Thermosynechococcus elongatus is compared in a photoelectrochemical system. The PSI monomer is isolated by disassembling a purified PSI trimer using a freeze-thaw technique in presence of the short-chain surfactant, octylthioglucoside. Photoactive electrodes are constructed with PSI, functioning as both light absorber and charge-separator, embedded within a conductive polymer film.

Photocurrent generation from surface assembled photosystem I on alkanethiol modified electrodes.

Photosystem I (PSI) is a key component of oxygenic photosynthetic electron transport because of its light-induced electron transfer to the soluble electron acceptor ferredoxin. This work demonstrates the incorporation of surface assembled cyanobacterial trimeric PSI complexes into a biohybrid system for light-driven current generation. Specifically, this work demonstrates the improved assembly of PSI via electrophoretic deposition, with controllable surface assembled PSI density, on different self-assembled alkanethiol monolayers.

Electrochemical characterization of riboflavin-enhanced reduction of trinitrotoluene.

There is great interest in understanding trinitrotoluene (TNT) and dinitrotoluene (DNT) contamination, detection and remediation in the environment due to TNT's negative health effects and security implications. Numerous publications have focused on detecting TNT in groundwater using multiple techniques, including electrochemistry. The main degradation pathway of nitrotoluenes in the environment is reduction, frequently with biological and/or photolytic assistance.

Metabolite analysis of Clostridium acetobutylicum: fermentation in a microbial fuel cell.

Microbial fuel cells (MFCs) were used to monitor metabolism changes in Clostridium acetobutylicum fermentations. When MFCs were inoculated with C. acetobutylicum, they generated a unique voltage output pattern where two distinct voltage peaks occurred over a weeklong period.

Modification of the optoelectronic properties of membranes via insertion of amphiphilic phenylenevinylene oligoelectrolytes.

We report on the modification of membranes by incorporation of phenylenevinylene oligoelectrolytes with the goal of tailoring their optical and electronic properties and their applications. A water-soluble distyrylstilbene oligoelectrolyte (DSSN+), capped at each end with nitrogen bound, terminally charged pendant groups, was synthesized. The photophysical and solvatochromatic properties of DSSN+ and the shorter distyrylbenzene analogue DSBN+ were probed and found to be useful for characterizing insertion into membranes based on phospholipid vesicle systems.

Mitigation of the effect of catholyte contamination in microbial fuel cells using a wicking air cathode.

Cathode design greatly affects microbial fuel cell (MFC) performance. Cathode contamination is inevitable in a single-chamber MFC yet it is impossible to study the magnitude of this effect in the single-chambered format. Therefore to study the effect of contamination at the cathode two-chamber MFCs must be used.

Effect of electron mediators on current generation and fermentation in a microbial fuel cell.

Effects of select electron mediators [9,10-anthraquinone-2,6-disulfonic acid disodium salt (AQDS), safranine O, resazurin, methylene blue, and humic acids] on metabolic end-products and current production from cellulose digestion by Clostridium cellulolyticum in microbial fuel cells (MFCs) were studied using capillary electrophoresis and traditional electrochemical techniques. Addition of the mediator resazurin greatly enhanced current production but did not appear to alter the examined fermentation end-products compared to MFCs with no mediator. Assays for lactate, acetate, and ethanol indicate that the presence of safranine O, methylene blue, and humic acids alters metabolite production in the MFC: safranine O decreased the examined metabolites, methylene blue increased lactate formation, and humic acids increased the examined metabolites.

Effect of molecular crowding on the response of an electrochemical DNA sensor.

E-DNA sensors, the electrochemical equivalent of molecular beacons, appear to be a promising means of detecting oligonucleotides. E-DNA sensors are comprised of a redox-modified (here, methylene blue or ferrocene) DNA stem-loop covalently attached to an interrogating electrode. Because E-DNA signaling arises due to binding-induced changes in the conformation of the stem-loop probe, it is likely sensitive to the nature of the molecular packing on the electrode surface.

Mediating electron transfer from bacteria to a gold electrode via a self-assembled monolayer.

Numerous bacterial genera are known to respire anaerobically using macroscopic electrodes as electron acceptors. Typically, inexpensive graphite electrodes, which are readily colonized, are used to monitor electrogenic bacterial metabolism for microbial fuel cell and bioelectronics studies. We compare current production by electrogenic bacteria on gold electrodes coated with various alkanethiol self-assembled monolayers to current production on glassy carbon electrodes.

Chitosan scaffolds for biomolecular assembly: coupling nucleic acid probes for detecting hybridization.

Chitosan, a naturally occurring biopolymer, was used as a scaffold for the covalent binding of single-stranded DNA oligonucleotide probes in a fluorescence-based nucleic acid hybridization assay. Chitosan's pH dependent chemical and electrostatic properties enable its deposition on electrodes and metal surfaces, as well as on the bottom of microtiter plates. A combinatorial 96-well microtiter plate format was used to optimize chemistries and reaction conditions leading to hybridization experiments.