Gold nanoparticle-based electrochemical magnetoimmunosensor for rapid detection of anti-hepatitis B virus antibodies in human serum

Nanomaterials based electrochemical sensors for biomedical applications

A growing variety of sensors have increasingly significant impacts on everyday life. Key issues to take into consideration toward the integration of biosensing platforms include the demand for minimal costs and the potential for real time monitoring, particularly for point-of-care applications where simplicity must also be considered. In light of these developmental factors, electrochemical approaches are the most promising candidate technologies due to their simplicity, high sensitivity and specificity. The primary focus of this review is to highlight the utility of nanomaterials, which are currently being studied for in vivo and in vitro medical applications as robust and tunable diagnostic and therapeutic platforms. Highly sensitive and precise nanomaterials based biosensors have opened up the possibility of creating novel technologies for the early-stage detection and diagnosis of disease related biomarkers. The attractive properties of nanomaterials have paved the way for the fabrication of a wide range of electrochemical sensors that exhibit improved analytical capacities. This review aims to provide insights into nanomaterials based electrochemical sensors and to illustrate their benefits in various key biomedical applications. This emerging discipline, at the interface of chemistry and the life sciences, offers a broad palette of opportunities for researchers with interests that encompass nanomaterials synthesis, supramolecular chemistry, controllable drug delivery and targeted theranostics in biology and medicine.

Magnetic nanoparticle-based immunosensor for electrochemical detection of hepatitis B surface antigen

An electrochemical immunosensor was developed for the detection of hepatitis B surface antigen (HBsAg). The biotinylated hepatitis B surface antibody was immobilized on streptavidin magnetic nanoparticles and used for targeting the HBsAg. By the addition of horseradish peroxidase conjugated with secondary antibody (HRP-HBsAb), a sandwich-type immunoassay format was formed. Aminophenol as substrate for conjugated HRP was enzymatically changed into 3-aminophenoxazone (3-APZ). This electroactive enzymatic production (3-APZ) was transferred into an electrochemical cell and monitored by cyclic voltammetry. Under optimal conditions, the cathodic current response of 3-APZ, which was proportional to the HBsAg concentration, was measured by a glassy carbon electrode. The immunosensor response was linear toward HBsAg in the concentration range from 0.001 to 0.015 ng/ml with a detection limit of 0.9 pg/ml at a signal/noise ratio of 3.

Detection of circulating cancer cells using electrocatalytic gold nanoparticles

A rapid cancer cell detection and quantification assay, based on the electrocatalytic properties of gold nanoparticles towards the hydrogen evolution reaction, is described. The selective labeling of cancer cells is performed in suspension, allowing a fast interaction between the gold nanoparticle labels and the target proteins expressed at the cell membrane. The subsequent electrochemical detection is accomplished with small volumes of sample and user-friendly equipment through a simple electrochemical method that generates a fast electrochemical response used for the quantification of nanoparticle-labeled cancer cells. The system establishes a selective cell-detection assay capable of detecting 4 × 10(3) cancer cells in suspension that can be extended to several other cells detection scenarios.

Simple monitoring of cancer cells using nanoparticles

Here we present a new strategy for a simple and fast detection of cancer circulating cells (CTCs) using nanoparticles. The human colon adenocarcinoma cell line (Caco2) was chosen as a model CTC. Similarly to other adenocarcinomas, colon adenocarcinoma cells have a strong expression of EpCAM, and for this reason this glycoprotein was used as the capture target. We combine the capturing capability of anti-EpCAM functionalized magnetic beads (MBs) and the specific labeling through antibody-modified gold nanoparticles (AuNPs), with the sensitivity of the AuNPs-electrocatalyzed hydrogen evolution reaction (HER) detection technique. The fully optimized process was used for the electrochemical detection of Caco2 cells in the presence of monocytes (THP-1), other circulating cells that could interfere in real blood samples. Therefore we obtained a novel and simple in situ-like sensing format that we applied for the rapid quantification of AuNPs-labeled CTCs in the presence of other human cells.

Casein modified gold nanoparticles for future theranostic applications

The synthesis and characterization of gold nanoparticles (AuNPs 20 nm sized) modified with k-casein derived peptides in order to monitor the peptide effect as bacterial adhesion inhibitor, thanks to the carrier/concentrator effect of the AuNPs is here presented. Some aspects related to the stability of AuNP/peptide conjugates for a potential application in the design of an electrochemical biosensor for pathogen bacteria detection are also discussed. This peptide based nanoparticle assay takes advantage of the dual character of the AuNPs: as carrier of the biorecognition molecule and also as electrocatalytic label, allowing the evaluation of the pathogen bacteria-peptide interaction in a simple and rapid way through the chronoamperometric monitoring of the hydrogen evolution reaction on screen-printed carbon electrodes. The developed proof of concept theranostic system may open the way to therapeutic and biosensing applications with interest for various fields.

Biosensors based on combined optical and electrochemical transduction for molecular diagnostics

Electrochemical and optical biosensors exist to monitor different fluids containing analytes of interest. Until today, these have been developed separately. Owing to the creation of new transducer configurations such as indium tin-coated glass fiber optics, these methods can now be used separately, in parallel and it is hoped that one day they will be able to be used simultaneously; thus, using the same probe to measure a single analyte using two different methods (electrochemical and optical) or two different analytes with either of the aforementioned methods sitting on the same probe. This article will highlight the importance, as well as the usefulness, of combining measurement methodologies in improving sensor response and sensitivity.

Noble metal nanoparticles for biosensing applications

In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios) that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory.

Magnetic Beads-Based Electrochemical Sensors Applied to the Detection and Quantification of Bioterrorism/Biohazard Agents

Nowadays, detecting the presence of bioterrorism and biohazard agents in environmental and food samples is of great concern, due to their toxicity, and because many of them are prone to be used in terrorism attacks. The use of functionalized magnetic beads (MBs) in the development of electrochemical immuno- and genosensors has resulted in innovative and powerful detection strategies that may be applied to environmental, food and clinical analysis. This review describes current research on the combination of functionalized MBs with electrochemical detection for the development of magnetobiosensors applied to rapid, sensitive and specific detection of bioterrorism and biohazard agents.