DNA-Hybridization Detection on Si(100) Surfaces Using Light-Activated Electrochemistry: A Comparative Study between Bovine Serum Albumin and Hexaethylene Glycol as Antifouling Layers.

Light can be used to spatially resolve electrochemical measurements on a semiconductor electrode. This phenomenon has been explored to detect DNA hybridization with light-addressable potentiometric sensors and, more recently, with light-addressable amperometric sensors based on organic-monolayer-protected Si(100). Here, a contribution to the field is presented by comparing sensing performances when bovine serum albumin (BSA) and hexaethylene glycol (OEG) are employed as antifouling layers that resist nonspecific adsorption to the DNA-modified interface on Si(100) devices.

Nucleic acid hybridization on an electrically reconfigurable network of gold-coated magnetic nanoparticles enables microRNA detection in blood.

There is intense interest in quantifying the levels of microRNA because of its importance as a blood-borne biomarker. The challenge has been to develop methods that can monitor microRNA expression both over broad concentration ranges and in ultralow amounts directly in a patient's blood. Here, we show that, through electric-field-induced reconfiguration of a network of gold-coated magnetic nanoparticles modified by probe DNA (DNA-Au@MNPs), it is possible to create a highly sensitive sensor for direct analysis of nucleic acids in samples as complex as whole blood.

Dual Signaling DNA Electrochemistry: An Approach To Understand DNA Interfaces.

Electrochemical DNA biosensors composed of a redox marker modified nucleic acid probe tethered to a solid electrode is a common experimental construct for detecting DNA and RNA targets, proteins, inorganic ions, and even small molecules. This class of biosensors generally relies on the binding-induced conformational changes in the distance of the redox marker relative to the electrode surface such that the charge transfer is altered. The conventional design is to attach the redox species to the distal end of a surface-bound nucleic acid strand.

Gold coated magnetic nanoparticles: from preparation to surface modification for analytical and biomedical applications.

Gold coated magnetic nanoparticles (Au@MNPs) have become increasingly interesting to nanomaterial scientists due to their multifunctional properties and their potential in both analytical chemistry and nanomedicine. The past decade has seen significant progress in the synthesis and surface modification of Au@MNPs. This progress is based on advances in the preparation and characterization of iron/iron oxide nanocrystals with the required surface functional groups.

Connecting electrodes with light: one wire, many electrodes.

The requirement of a wire to each electrode is central to the design of any electronic device but can also be a major restriction. For example it entails space restrictions and rigid device architecture in multi-electrode devices. The finite space that is taken up by the array of electrical terminals and conductive pads also severely limits the achievable density of electrodes in the device.

Nucleic-acid recognition interfaces: how the greater ability of RNA duplexes to bend towards the surface influences electrochemical sensor performance.

The influence of RNA versus DNA on the performance of electrochemical biosensors where redox-labelled nucleic acid duplexes bend towards the electrode surface has been assessed. Faster electron transfer was observed for duplexes containing RNA, suggesting duplexes with RNA are more flexible. These data are of particular importance for microRNA biosensors.

Quantitative determination of target gene with electrical sensor.

Integrating loop-mediated isothermal amplification (LAMP) with capacitively coupled contactless conductivity detection (C(4)D), we have developed an electrical sensor for the simultaneous amplification and detection of specific sequence DNA. Using the O26-wzy gene as a model, the amount of initial target gene could be determined via the threshold time obtained by monitoring the progression of the LAMP reaction in real time. Using the optimal conditions, a detection limit of 12.

Phenazine virulence factor binding to extracellular DNA is important for Pseudomonas aeruginosa biofilm formation.

Bacterial resistance to conventional antibiotics necessitates the identification of novel leads for infection control. Interference with extracellular phenomena, such as quorum sensing, extracellular DNA integrity and redox active metabolite release, represents a new frontier to control human pathogens such as Pseudomonas aeruginosa and hence reduce mortality. Here we reveal that the extracellular redox active virulence factor pyocyanin produced by P.

Toward biosensors for the detection of circulating microRNA as a cancer biomarker: an overview of the challenges and successes.

Considerable attention has been dedicated to developing feasible point-of-care tests for cancer diagnosis and prognosis. An ideal biomarker for clinical use should be easily assayed with minimally invasive medical procedures but possess high sensitivity and specificity. The role of microRNAs (miRNAs) in the regulation of different cellular processes, the unique altered patterns in cancer patients and presence in body fluids in the stable form, points to their clinical utility as blood-based biomarkers for diagnosis, prognosis, and treatment of cancer.

Simultaneous determination of penicillin G salts by infrared spectroscopy: Evaluation of combining orthogonal signal correction with radial basis function-partial least squares regression.

In this study, a new method for the simultaneous determination of penicillin G salts in pharmaceutical mixture via FT-IR spectroscopy combined with chemometrics was investigated. The mixture of penicillin G salts is a complex system due to similar analytical characteristics of components. Partial least squares (PLS) and radial basis function-partial least squares (RBF-PLS) were used to develop the linear and nonlinear relation between spectra and components, respectively.