Characterizing a Silver Nanoparticle-Based Electrochemical Biosensor for Shiga Toxin Detection.

Shiga toxins (1, 2) regularly cause outbreaks and food recalls and pose a significant health risk to the infected population. Therefore, new reliable tools are needed to rapidly detect Shiga toxin cost-effectively in food, water, and wastewater before human consumption. Enzyme immunoassay and polymerase chain reaction approaches are the gold standard detection methods for the Shiga toxin.

Compression of the vascular wall to create a friction fit in a vascular anastomotic coupler.

A previously reported microvascular coupler was shown to effectively create vascular anastomoses, but was too large for practical clinical use. To safely reduce coupler size, certain failure modes needed to be better understood. The coupler functions, in part, by compressing the vessel wall between two concentric rings, creating a friction fit that anchors the device to the vessel.

SARS-CoV-2 pandemic: a review of molecular diagnostic tools including sample collection and commercial response with associated advantages and limitations.

The unprecedented global pandemic known as SARS-CoV-2 has exercised to its limits nearly all aspects of modern viral diagnostics. In doing so, it has illuminated both the advantages and limitations of current technologies. Tremendous effort has been put forth to expand our capacity to diagnose this deadly virus.

Hydrodynamic cavitation for the rapid separation and electrochemical detection of Cryptosporidium parvum and Escherichia coli O157:H7 in ground beef.

Foodborne illnesses are a major contributor to misery and health challenges in both rich and poor nations. Illnesses from pathogens such as Escherichia coli and Cryptosporidium parvum oocysts account for most of the cases of diarrhea in the world. Many standard methods exist for detecting these pathogens in water.

Electrochemical Detection of O157:H7 in Water after Electrocatalytic and Ultraviolet Treatments Using a Polyguanine-Labeled Secondary Bead Sensor.

The availability of clean drinking water is a significant problem worldwide. Many technologies exist for purifying drinking water, however, many of these methods require chemicals or use simple methods, such as boiling and filtering, which may or may not be effective in removing waterborne pathogens. Present methods for detecting pathogens in point-of-use (POU) sterilized water are typically time prohibitive or have limited ability differentiating between active and inactive cells.

Transdermal Delivery of siRNA through Microneedle Array.

Successful development of siRNA therapies has significant potential for the treatment of skin conditions (alopecia, allergic skin diseases, hyperpigmentation, psoriasis, skin cancer, pachyonychia congenital) caused by aberrant gene expression. Although hypodermic needles can be used to effectively deliver siRNA through the stratum corneum, the major challenge is that this approach is painful and the effects are restricted to the injection site. Microneedle arrays may represent a better way to deliver siRNAs across the stratum corneum.

Highly sensitive bacteria quantification using immunomagnetic separation and electrochemical detection of guanine-labeled secondary beads.

In this paper, we report the ultra-sensitive indirect electrochemical detection of E. coli O157:H7 using antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized secondary (polystyrene) beads as an electrochemical tag. Vacuum filtration in combination with E.

Improved polyvinylpyrrolidone microneedle arrays with non-stoichiometric cyclodextrin.

Dissolving polymer microneedles have attracted much attention for their biocompatibility, fast dissolution, and high drug loading. Among them, polyvinylpyrrolidone (PVP) is widely used, but its high water absorption and poor mechanical properties constrain its broad applications. Herein we show that adding cyclodextrin (CD) to form PVP-CD inclusion complexes can alleviate these problems.

Nanocomposite-strengthened dissolving microneedles for improved transdermal delivery to human skin.

Delivery of drugs and biomolecules into skin has significant advantages. To achieve this, herein, a nanomaterial-strengthened dissolving microneedle patch for transdermal delivery is reported. The patch comprises thousands of microneedles, which are composed of dissolving polymers, nanomaterials, and drug/biomolecules in their interior.

New approaches to bridge nerve gaps: development of a novel drug-delivering nerve conduit.

Contemporary bridging techniques for repairing nerve gaps caused by trauma require autologous nerve grafts, which are difficult to harvest and handle and result in significant donor site deficit. Several nerve conduits with axon growth-enhancing potential have been proposed, developed and tested over the past fifteen years. In this work, prototypes of a nerve conduit designed to bridge large nerve gaps (≥10mm) end-to-end were incorporated with concentric drug reservoirs for constant and controlled drug delivery to enhance axon growth.

Applications of microfluidics for molecular diagnostics.

Diagnostic assays implemented in microfluidic devices have developed rapidly over the past decade and are expected to become commonplace in the next few years. Hundreds of microfluidics-based approaches towards clinical diagnostics and pathogen detection have been reported with a general theme of rapid and customizable assays that are potentially cost-effective. This chapter reviews microfluidics in molecular diagnostics based on application areas with a concise review of microfluidics in general.

Diffusion Split-Flow Thin Cell (SPLITT) system for protein separations.

A diffusion Split-Flow Thin Cell (SPLITT) system was used to partially remove small peptides such as β2 microglobulin (β2M) and parathyroid hormone (PTH) in a continuous manner from an input flow stream while preserving most (over 97%) of the larger protein in the sample, such as albumin. To help determine the operating conditions for this work, a two-dimensional numerical model based on the Navier-Stokes equation and convection-diffusion equations was developed for diffusional SPLITT using COMSOL multiphysics software (COMSOL Inc., MA).

A novel method for effective field measurements in electrical field-flow fractionation.

The electric field that drives separation and retention in electrical field flow fractionation (ElFFF) and cyclical electrical field-flow fractionation (CyElFFF) is a complex function of many parameters such as carrier ionic strength and pH, voltage, channel dimensions, flowrate, and electrode material. Currently there is no accurate or in situ method to measure the field during system operation. This paper introduces a technique to measure the effective electric field during ElFFF and CyElFFF operation using transient electrical spikes.

Characterization of a microscale thermal-electrical field-flow fractionation system.

A microscale thermal-electrical field-flow fractionation (ThElFFF) channel is reported for the first time and preliminary characterization results show high retention at certain operating conditions including relatively high flow rates when compared to standard microscale electrical or thermal field-flow fractionation instruments. A new design is presented that simplifies manufacturing and assembly of the prototype and that can provide both an electrical field and a high temperature gradient (∼10⁶ °C/m). Monodisperse particle retention is carried out with polystyrene nanoparticle samples to characterize the device.

Reduction of end effect-induced zone broadening in field-flow fractionation channels.

A channel configuration for the elimination of end effects in field-flow fractionation (FFF) channels is simulated and demonstrated for a microfabricated FFF system. In field-flow fractionation, the carrier liquid and sample particles are transferred from a point injection to the full breadth of the rectangular channel using a triangular end piece at the inlet. The nonuniformity in streamline length generated by this end piece results in an increased instrument-related plate height.

Geometric scaling effects on instrumental plate height in field flow fractionation.

This paper examines geometric scaling models for field flow fractionation systems to understand how channel dimensions affect resolution and retention. Specifically, the changing contribution of the instrumental plate height during miniaturization of field flow fractionation (FFF) systems is reported. The work is directed towards determining the optimal geometrical parameters for miniaturization of field flow fractionation systems.