Quantitative Measurements of Protein Volume and Concentration using Hydrogel-Backed Nanopores.

Accurate identification and quantification of proteins in solution using nanopores is technically challenging in part because of the large fraction of missed translocation events due to short event times and limitations of conventional current amplifiers. Previously, we have shown that a nanopore interfaced with a poly(ethylene glycol)-dimethacrylate hydrogel with an average mesh size of 3.1 nm significantly enhances the protein residence time within the pore, reducing the number of missed events.

Implantable Drug Reservoir Devices for Inner Ear Delivery of Pharmacotherapeutics.

Objective: Cisplatin is a platinum-based chemotherapeutic drug that secondarily induces toxicity in inner ear sensory epithelia, contributing to auditory and vestibular dysfunction. We describe the creation of a drug reservoir device (DRD) to combat this ototoxicity for the duration of chemotherapy. As ototoxic side effects of chemotherapy may limit an oncologist's ability to prescribe first-line agents such as cisplatin, mitigating such devastating effects through prolonged topical therapy would be tremendously valuable.

Improved Measurement of Proteins Using a Solid-State Nanopore Coupled with a Hydrogel.

Although resistive pulse sensing using solid-state nanopores is capable of single-molecule sensitivity, previous work has shown that nanoparticles, such as proteins, pass through nanopores too quickly for accurate detection with typical measurement apparatus. As a result, nanopore measurements of these particles significantly deviate from theoretically estimated current amplitudes and detection rates. Here, we show that a hydrogel placed on the distal side of a nanopore can increase the residence time of nanoparticles within the nanopore, significantly increasing the detection rate and allowing improved resolution of blockage currents.

Addition of Cleaved Tail Fragments during Lipid Oxidation Stabilizes Membrane Permeability Behavior.

Lipid oxidation has been linked to plasma membrane damage leading to cell death. In previous work, we examined the effect of oxidation on bilayer permeability by replacing defined amounts of an unsaturated lipid species with the corresponding phospholipid product that would result from oxidative tail scission of that species. This study adds the cleaved tail fragment, better mimicking the chemical results of oxidation.

Measurement of Ensemble TRPV1 Ion Channel Currents Using Droplet Bilayers.

Electrophysiological characterization of ion channels is useful for elucidation of channel function as well as quantitative assessment of pharmaceutical effects on ion channel conductance. We used droplet bilayers to measure ensemble ion channel currents from membrane preparations made from TRPV1-expressing HEK cells. Conductance measurements showed rectification, activation by acid and capsaicin, and inhibition by capsazepine, SB 452533, and JNJ 17293212.

Research highlights: nanopore protein detection and analysis.

In this article we highlight recent work using nanopores to detect and study proteins. Nanopores are excellent single molecule sensors, capable of rapidly characterizing small molecules with relatively modest instrumentation requirements. Although the vast majority of recent effort and attention surrounding nanopores has centered on detection and sequencing of nucleic acids, proteins represent a more difficult and diverse analyte population, with a wide range of sizes, structures, charges, among other characteristics.

Single channel and ensemble hERG conductance measured in droplet bilayers.

The human ether-a-go-go related gene (hERG) encodes the potassium channel Kv11.1, which plays a key role in the cardiac action potential and has been implicated in cardiac disorders as well as a number of off-target pharmaceutical interactions. The electrophysiology of this channel has been predominantly studied using patch clamp, but lipid bilayers have the potential to offer some advantages, including apparatus simplicity, ease of use, and the ability to control the membrane and solution compositions.

Mixed-effects modeling of clinical DCE-MRI data: application to colorectal liver metastases treated with bevacizumab.

Purpose: Most dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data are evaluated for individual patients with cohorts analyzed to detect significant changes from baseline values, repeating the process at each posttreatment timepoint. Our study aimed to develop a statistically valid model for the complete time course of DCE-MRI data in a patient cohort.

Materials And Methods: Data from 10 patients with colorectal cancer liver metastases were analyzed, including two baseline scans and four post-bevacizumab scans.

Hydrogel-stabilized droplet bilayers for high speed solution exchange.

Many applications utilizing artificial lipid bilayers require the ability to exchange the bilayer's solution environment. However, because of the instability of the bilayer, the rate of solution exchange is limited, which significantly hinders the measurement rate and throughput. We have developed an artificial bilayer system that can withstand high flow speeds, up to 2.