Search

The improvements in our ability to sequence and genotype DNA have opened up numerous avenues in the understanding of human biology and medicine with various applications, especially in medical diagnostics. But the realization of a label free, real time, high-throughput and low cost biosensing platforms to detect molecular interactions with a high level of sensitivity has been yet stunted due to two factors: one, slow binding kinetics caused by the lack of probe molecules on the sensors and two, limited mass transport due to the planar structure (two-dimensional) of the current biosensors. Here we present a novel three-dimensional (3D), highly sensitive, real-time, inexpensive and label-free nanotip array as a rapid and direct platform to sequence-specific DNA screening. Our nanotip sensors are designed to have a nano sized thin film as their sensing area (~ 20 nm), sandwiched between two sensing electrodes. The tip is then conjugated to a DNA oligonucleotide complementary to the sequence of interest, which is electrochemically detected in real-time via impedance changes upon the formation of a double-stranded helix at the sensor interface. This 3D configuration is specifically designed to improve the biomolecular hit rate and the detection speed. We demonstrate that our nanotip array effectively detects oligonucleotides in a sequence-specific and highly sensitive manner, yielding concentration-dependent impedance change measurements with a target concentration as low as 10 pM and discrimination against even a single mismatch. Notably, our nanotip sensors achieve this accurate, sensitive detection without relying on signal indicators or enhancing molecules like fluorophores. It can also easily be scaled for highly multiplxed detection with up to 5000 sensors/square centimeter, and integrated into microfluidic devices. The versatile, rapid, and sensitive performance of the nanotip array makes it an excellent candidate for point-of-care diagnostics, and high-throughput DNA analysis applications.

In this reflective essay, we describe Widener University's 10-year transformation from a disengaged institution to an institution that has a metropolitan-focused mission vested in civic leadership, community engagement, and service-learning. We describe our journey to embed an expansive civic frame that includes concrete practices of pedagogy, institutional engagement, and community partnerships. We discuss the rewards and challenges of engaging in long-term, democratic, collaborative work, offering a unique insight about the role of a private, mid-size university in anchor-based engagement. We conclude that Widener's strategy for achieving comprehensive community and economic development is responsible for sustaining multi-anchor regional and local partnerships.

Patients with retinal degeneration lose sight due to the gradual demise of photoreceptors. Electrical stimulation of surviving retinal neurons provides an alternative route for the delivery of visual information. We demonstrate that subretinal implants with 70-μm-wide photovoltaic pixels provide highly localized stimulation of retinal neurons in rats. The electrical receptive fields recorded in retinal ganglion cells were similar in size to the natural visual receptive fields. Similarly to normal vision, the retinal response to prosthetic stimulation exhibited flicker fusion at high frequencies, adaptation to static images and nonlinear spatial summation. In rats with retinal degeneration, these photovoltaic arrays elicited retinal responses with a spatial resolution of 64 ± 11 μm, corresponding to half of the normal visual acuity in healthy rats. The ease of implantation of these wireless and modular arrays, combined with their high resolution, opens the door to the functional restoration of sight in patients blinded by retinal degeneration.

Increasingly, the success of management interventions aimed at biodiversity conservation are viewed as being dependent on the ‘resilience’ of the system. Although the term ‘resilience’ is increasingly used by policy makers and environmental managers, the concept of ‘resilience’ remains vague, varied and difficult to quantify. Here we clarify what this concept means from an ecological perspective, and how it can be measured and applied to ecosystem management. We argue that thresholds of disturbance are central to measuring resilience. Thresholds are important because they offer a means to quantify how much disturbance an ecosystem can absorb before switching to another state, and so indicate whether intervention might be necessary to promote the recovery of the pre-disturbance state. We distinguish between helpful resilience, where resilience helps recovery, and unhelpful resilience where it does not, signalling the presence of a threshold and the need for intervention. Data to determine thresholds are not always available and so we consider the potential for indices of functional diversity to act as proxy measures of resilience. We also consider the contributions of connectivity and scale to resilience and how to incorporate these factors into management. We argue that linking thresholds to functional diversity indices may improve our ability to predict the resilience of ecosystems to future, potentially novel, disturbances according to their spatial and temporal scales of influence. Throughout, we provide guidance for the application of the resilience concept to ecosystem management. In doing so, we confirm its usefulness for improving biodiversity conservation in our rapidly changing world.

BackgroundIt is assumed that the oxytocin receptor gene (OXTR) is associated with factors that are related to features of reproduction as well as the currently emerging fields of mood and emotional response.MethodsWe analysed data from over 8000 mothers who participated in the Avon Longitudinal Study of Parents and Children (ALSPAC). We determined reproductive, emotional and personality differences related to the two SNPs rs53576 and rs2254298 of the oxytocin receptor gene to determine whether there was evidence in this population for: (i) associations with emotional and personality differences, and (ii) behavioural or environmental links with these SNPs using a hypothesis free approach with over 1000 types of exposure.ResultsOur analyses of 7723 women showed that there were no differences in 11 mood, social or relationship characteristics associated with the rs2254298, and just one with rs53576 (with emotional loneliness)--one statistically significant out of 22 tests is no more than would be expected by chance. There were no interactions with childhood abuse. Using a hypothesis-free approach we found few indicators of environmental or behavioural differences associated with rs2254298, but there was an excess of associations with eating habits with rs53576. The findings included an association with dieting to lose weight, and habits typical of bulimia for the women with GG. The nutrition of the women also showed negative associations of the GG genotype with 13 nutrients, including vitamins D, B12 and retinol, and intake of calcium, potassium and iodine.ConclusionsWe conclude that this large database of pregnant women was unable to provide confirmation of the types of personality associated with these two OXTR SNPs, but we have shown some evidence of eating differences in those with GG on rs53576. Confirmation of our hypothesis free associations using other data sets is important.

X-ray nanotomography is a powerful tool for the characterization of nanoscale materials and structures, but it is difficult to implement due to the competing requirements of X-ray flux and spot size. Due to this constraint, state-of-the-art nanotomography is predominantly performed at large synchrotron facilities. We present a laboratory-scale nanotomography instrument that achieves nanoscale spatial resolution while addressing the limitations of conventional tomography tools. The instrument combines the electron beam of a scanning electron microscope (SEM) with the precise, broadband X-ray detection of a superconducting transition-edge sensor (TES) microcalorimeter. The electron beam generates a highly focused X-ray spot on a metal target held micrometers away from the sample of interest, while the TES spectrometer isolates target photons with a high signal-to-noise ratio. This combination of a focused X-ray spot, energy-resolved X-ray detection, and unique system geometry enables nanoscale, element-specific X-ray imaging in a compact footprint. The proof of concept for this approach to X-ray nanotomography is demonstrated by imaging 160 nm features in three dimensions in six layers of a Cu-SiO2 integrated circuit, and a path toward finer resolution and enhanced imaging capabilities is discussed. [ABSTRACT FROM AUTHOR]