Self-Assembly and Rearrangement of a Polyproline II Helix Peptide on Gold.

Polyproline peptide sequences have gained popularity as anchors for peptide-based self-assembled monolayers (SAMs) due to their attractive properties. In this work, peptides containing the polyproline II helix (PPII) conformation were designed and assembled on gold (Au). A quartz crystal microbalance with dissipation was used to characterize SAM formation kinetics and related properties. Peptides were designed with the sequence (GPPPPPG)2C. It was discovered that a biexponential adsorption and rearrangement model describes the binding kinetics of the PPII-containing peptide on Au. In this model, an initial reversible binding step is followed by an irreversible rearrangement step, given by parameter kt. This study found kt to be approximately 0.00064 s-1 for the PPII-containing peptides. Similarly, we found that the adsorption of the PPII-containing peptide on Au, given by ΔGads, was thermodynamically favorable (-7.8 kcal mol-1) and comparable to other common thiol terminated SAMs on Au. Furthermore, we characterized SAM properties via QCM-D, Fourier-transform infrared (FTIR) spectroscopy, and electrochemical techniques to reveal high molecular density SAMs consisting of PPII helices. In addition, these SAMs were found to have high antifouling properties. Overall, this study characterizes the fundamental assembly mechanisms, particularly, rearrangement of PPII-containing peptides for the first time, which will be useful in the designing of future peptide-based SAMs with high surface coverage and antifouling properties.

Controlling the Distribution of Perfluorinated Sulfonic Acid Ionomer with Elastin-like Polypeptide.

Proton-exchange-membrane (PEM)-based devices are promising technologies for hydrogen production and electricity generation. Currently, the amount of expensive platinum catalyst used in these devices must be reduced to be cost-competitive with other technologies. These devices typically contain Nafion ionomer thin films in the catalyst layers, which are responsible for transporting protons and gaseous species to and from electrochemically active sites. The morphology of the Nafion ionomer thin films in the catalyst layers with reduced platinum loading is impacted by interactions with the catalyst and the confinement to nanometer thicknesses, which leads to performance losses in PEM-based devices. In this study, an elastin-like polypeptide (ELP) is designed to modulate the morphology of Nafion ionomer on platinum surfaces. The ELP shows an ability to assemble into a monolayer on platinum and change the ionomer interaction with platinum, thereby modifying its thin-film structure and improving the Nafion ionomer coverage. As a proof of concept, an ELP-modified catalyst ink was prepared and morphological differences were observed. Overall, we discovered an engineered ELP that can modulate the ionomer-catalyst interface in the electrodes of PEM-based devices.

Mass gathering enhanced syndromic surveillance for the 8th Micronesian Games in 2014, Pohnpei State, Federated States of Micronesia.

Pohnpei State's Division of Primary Health Care implemented enhanced surveillance for early warning and detection of disease to support the 8th Micronesian Games (the Games) in July 2014. The surveillance comprised 11 point-of-care sentinel sites around Pohnpei, Federated States of Micronesia, collecting data daily for eight syndromes using standard case definitions. Each sentinel site reported total acute care encounters, total syndrome cases and the total for each syndrome. A public health response, including epidemiological investigation and laboratory testing, followed when syndrome counts reached predetermined threshold levels. The surveillance was implemented using the web-based Suite for Automated Global Electronic bioSurveillance Open-ESSENCE (SAGES-OE) application that was customized for the Games. Data were summarized in daily situation reports (SitReps) issued to key stakeholders and posted on PacNet, a Pacific public health e-mail network. Influenza-like illness (ILI) was the most common syndrome reported (55%, n = 225). Most syndrome cases (75%) were among people from Pohnpei. Only 30 cases out of a total of 408 syndrome cases (7%) presented with acute fever and rash, despite the large and ongoing measles outbreak at the time. No new infectious disease outbreak was recorded during the Games. Peaks in diarrhoeal and ILI cases were followed up and did not result in widespread transmission. The technology was a key feature of the enhanced surveillance. The introduction of the web-based tool greatly improved the timeliness of data entry, analysis and SitRep dissemination, providing assurance to the Games organizers that communicable diseases would not adversely impact the Games.