Monica Florescu

Publications (14) View all

• Article: Double layered nanostructured composite coatings with bioactive silicate glass and polymethylmetacrylate for biomimetic implant applications

  Laura Floroian, F. Sima, Monica Florescu, Mihaela Badea, A.C. Popescu, N. Serban, I.N. Mihailescu
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  ABSTRACT: We studied the corrosion behaviour of bioactive glass–polymer nanostructured coatings of titanium implants for prostheses. The layers were deposited by MAPLE on titanium substrates of biomedical use. The potentiodynamic polarization investigations showed that the obtained samples exhibited a higher corrosion resistance as compared to bare titanium. The behaviour of coatings in contact with physiological fluids was studied in vitro by electrochemical impedance spectroscopy. The initial bioactive glass–polymer coating proved to be a good insulator. After immersion in simulated body fluid the bioactive glass dissolution and the adsorption of electrolyte ions were initiated causing the formation of an outer bioapatite protective layer. A simple cell circuit proved sufficient to describe unimmersed, short (7 days) and/or long (42 days) time immersed samples at room temperature, while after 14, 21, 28 or 35 immersion days, the use of a double cell circuit was mandatory. This was indicative for the formation of a double nanostructure consisting of an inner barrier (mainly polymer) and an outer porous (bioapatite) film with potential beneficial effects for osseointegration capacity of the Ti implants.
  Journal of electroanalytical chemistry 01/2010; 648:111-118. · 2.90 Impact Factor
• Source

  Available from: uc.pt

  Article: Development and characterization of a new conducting carbon composite electrode.

  Madalina M Barsan, Edilson M Pinto, Monica Florescu, Christopher M A Brett
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  ABSTRACT: A new conducting composite flexible material prepared from cellulose acetate (CA) polymer and graphite has been developed and used for the fabrication of electrodes, which were then characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM) was used to provide information concerning the morphology of the composite electrode surface. The potential window, background currents and capacitance were evaluated by cyclic voltammetry in the pH range from 4.6 to 8.2. The voltammetry of model electroactive species demonstrates a close to reversible electrochemical behaviour, under linear diffusion control. The electroactive area of the composite electrodes increases after appropriate electrode polishing and electrochemical pre-treatment. The electrodes were used as substrate for the electropolymerisation of the phenazine dye neutral red, for future use as redox mediator in electrochemical biosensors. The composite electrodes were also successfully used for the amperometric detection of ascorbate at 0.0 V vs. SCE, and applied to the measurement of ascorbate in Vitamin C tablets; the sensor exhibits high sensitivity and a low detection limit of 7.7 microM. Perspectives for use as a versatile, mechanically flexible and robust composite electrode of easily adaptable dimensions are indicated.
  Analytica chimica acta 04/2009; 635(1):71-8. · 4.31 Impact Factor
• Source

  Available from: getion.ro

  Article: EVALUATION OF COBALT HEXACYANOFERRATE MODIFIED CARBON FILM ELECTRODES FOR ELECTROCHEMICAL GLUCOSE BIOSENSORS

  Monica Florescu, Christopher M A Brett
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  ABSTRACT: The evaluation and electrochemical characterisation of new glucose oxidase electrochemical enzyme biosensors on a carbon film electrode support using two types of enzyme immobilisation has been carried out, with a view to their application as short-time-use or disposable sensors. Carbon film electrodes have been modified with films of cobalt hexacyanoferrate (CoHCF) redox mediator by potential cycling from solutions containing cobalt and hexacyanoferrate ions. Enzyme immobilisation onto the electrode surface was done using cross-linking methods with glutaraldehyde and oxysilane sol-gel polymers. Application of the modified electrodes as redox mediators in glucose enzyme biosensors was investigated using the mediated detection of hydrogen peroxide, with excellent detection limits in the micromolar region.
  Revue Roumaine de Chimie 01/2007; 52:969-974. · 0.42 Impact Factor
• Article: Development and Application of Oxysilane Sol–Gel Electrochemical Glucose Biosensors Based on Cobalt Hexacyanoferrate Modified Carbon Film Electrodes

  Monica Florescu, Madalina Barsan, Rasa Pauliukaite, Christopher M. A. Brett
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  ABSTRACT: The evaluation and characterization of a new glucose oxidase (GOx) electrochemical enzyme biosensors on a carbon film electrode support and using two types of sol–gel precursor mixture for enzyme immobilization was carried out in order to be employed as a short-time-use or as a disposable sensor. Carbon film electrodes were modified with films of CoHCF mediator by potential cycling. The sol–gel was prepared using a combination of 3-glycidoxypropyltrimethoxysilane (GOPMOS) with methyltrimethoxysilane (MTMOS) or tetraethoxysilane (TEOS).
  Electroanalysis 12/2006; 19(2‐3):220 - 226. · 2.87 Impact Factor
• Source

  Available from: Emilia Ghica

  Article: A strategy for enzyme immobilization on layer-by-layer dendrimer-gold nanoparticle electrocatalytic membrane incorporating redox mediator

  Frank N Crespilho, M Emilia Ghica, Monica Florescu, Francisco C Nart, Osvaldo N Oliveira, Christopher M A Brett
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  ABSTRACT: A new approach is described to produce nanostructured electrocatalytic membranes using a combination of three methods. Using the layer-by-layer technique, PAMAM dendrimers with cobalt hexacyanoferrates-modified gold nanoparticles were alternated with poly(vinylsulfonic acid) layers on ITO (indium tin oxide) electrodes. This film was used as substrate for immobilization of glucose oxi-dase in the presence of bovine serum albumin and glutaraldehyde as cross-linker. The modified electrode was successfully applied as a biosensor for the amperometric measurement of glucose, using glucose oxidase enzyme, at 0.0 V vs. SCE.
  09/2006;