Anca Florea

Carbon Based Electrodes Modified with Horseradish Peroxidase Immobilized in Conducting Polymers for Acetaminophen Analysis

The development and optimization of new biosensors with horseradish peroxidase immobilized in carbon nanotubes-polyethyleneimine or polypyrrole nanocomposite film at the surface of two types of transducer is described. The amperometric detection of acetaminophen was carried out at −0.2 V versus Ag/AgCl using carbon based-screen printed electrodes (SPEs) and glassy carbon electrodes (GCEs) as transducers. The electroanalytical parameters of the biosensors are highly dependent on their configuration and on the dimensions of the carbon nanotubes. The best limit of detection obtained for acetaminophen was 1.36 ± 0.013 μM and the linear range 9.99–79.01 μM for the HRP-SWCNT/PEI in GCE configuration. The biosensors were successfully applied for the detection of acetaminophen in several drug formulations.

Anticancer drug detection using a highly sensitive molecularly imprinted electrochemical sensor based on an electropolymerized microporous metal organic framework

A simple and highly sensitive approach for the detection of the anti-neoplastic drug gemcitabine is presented, based on a one-step electropolymerized molecularly imprinted microporous-metal-organic-framework. The sensitive layer was prepared by electropolymerization of the aniline moieties of p-aminothiophenol- gold nanoparticles on the surface of gold electrodes tethered with p-aminothiophenol, in the presence of gemcitabine as a template molecule. Experimental parameters that control the performance of the sensor were investigated and optimized. Under optimal conditions a calibration curve was obtained in the linear range from 3.8 fM to 38 nM with a limit of detection of 3 fM. The obtained imprinted sensor has the advantages of easy manufacture, high sensitivity and selectivity and good reproducibility. Furthermore the feasibility of the proposed technique has been investigated on spiked serum samples and infusion solution containing gemcitabine.

Molecularly imprinted polymer-based electrochemical sensor for the sensitive detection of glyphosate herbicide

ABSTRACT A sensitive electrochemical molecularly imprinted sensor was developed for the detection of glyphosate (Gly), by electropolymerisation of p-aminothiophenol-functionalised gold nanoparticles in the presence of Gly as template molecule. The extraction of the template leads to the formation of cavities that are able to specifically recognise and bind Gly through hydrogen bonds between Gly molecules and aniline moieties. The performance of the developed sensor for the detection of Gly was investigated by linear sweep voltammetry using a hexacyanoferrate/hexacyanoferrite solution as redox probe, the electron transfer rate increasing when concentration of Gly increases, due to a p-doping effect. The molecularly imprinted sensor exhibits a broad linear range, between 1 pg/L and 1 µg/L and a quantification limit of 0.8 pg/L. The selectivity of the proposed sensor was investigated towards the binding of Gly metabolite, aminomethylphosphonic acid, revealing excellent selectivity towards Gly. The developed sensor was successfully applied to detect Gly in tap water samples.

Aflatoxin B1 Detection Using a Highly-Sensitive Molecularly-Imprinted Electrochemical Sensor Based on an Electropolymerized Metal Organic Framework

A sensitive electrochemical molecularly-imprinted sensor was developed for the detection of aflatoxin B1 (AFB1), by electropolymerization of p-aminothiophenol-functionalized gold nanoparticles in the presence of AFB1 as a template molecule. The extraction of the template leads to the formation of cavities that are able to specifically recognize and bind AFB1 through π-π interactions between AFB1 molecules and aniline moities. The performance of the developed sensor for the detection of AFB1 was investigated by linear sweep voltammetry using a hexacyanoferrate/hexacyanoferrite solution as a redox probe, the electron transfer rate increasing when the concentration of AFB1 increases, due to a p-doping effect. The molecularly-imprinted sensor exhibits a broad linear range, between 3.2 fM and 3.2 µM, and a quantification limit of 3 fM. Compared to the non-imprinted sensor, the imprinting factor was found to be 10. Selectivity studies were also performed towards the binding of other aflatoxins and ochratoxin A, proving good selectivity.

Innovative Immunosensors for Early Stage Cancer Diagnosis and Therapy Monitoring

This paper addresses the development of a diagnosis device based on optical and electrochemical principles for the detecting the levels of multiple mucin (MUC) type biomarkers. Combining surface plasmon resonance (SPR) and electrochemical techniques the selectivity can lead to improved sensitivity and reliability of the obtained transducer. The structures appropriate for an easy operated device, not requiring highly skilled operating personnel or expensive instrumentation, while offering fast, selective and accurate analytical response are investigated. A diagnosis device based on such combined immunosensor can greatly improve the chances of early diagnosis of ovarian cancer.

Electrochemical Immunoassay for Mucin 1 Detection as a Diagnostic Tool in Ovarian Cancer

The immunoassay developed for Mucin 1 (MUC1) detection is based on a sandwich format in which a primary antibody immobilized on the surface of magnetic beads specifically binds the MUC1 protein. The sandwich immunoassay is performed by adding secondary anti-MUC1 and an alkaline-phosphatase-labeled third antibody. After, the modified magnetic beads are captured by a magnet on the surface of a graphite working electrode, and the electrochemical detection is thus achieved through the addition of 1-naphthyl phosphate. 1-naphthol, produced during the enzymatic reaction, is detected using differential pulse voltammetry (DPV). The performance of the assay in terms of sensitivity, reproducibility, and selectivity has been studied. MUC1 detection is performed in buffered solutions and serum sample.

Designing polymer-based immunosensing platforms for cancer biomarker detection

The detection of multiple cancer biomarkers in human serum plays an important role for early cancer detection and represents a challenge to the development of biosensing devices. Mucines are glycoproteins, expressed in physiological conditions on the surface of epithelial tissues with role in lubrication. Several studies showed the implication of mucins (e.g. MUC1, MUC4) in the pathogenesis of ovarian cancer. This paper reviews the preliminary results of a few approaches performed in our laboratory for the design of immunosensors for mucines tumor markers detection using various immobilization platforms. Different strategies have been employed using magnetic nanobeads and conducting polymer/multiwall carbon nanotube composite films for the immobilization of the capturing antigen.