Laura Floroian

Ochratoxin A Detection on Antibody- Immobilized on BSA-Functionalized Gold Electrodes

Ochratoxin A (OTA)—a toxin produced by Aspergillus carbonarius, Aspergillus ochraceus, and Penicillium verrucosum—is one of the most-abundant food-contaminating mycotoxins. To avoid the risk of OTA consumption for humans and animals, the rapid detection and quantitation of OTA level in different commodities are of great importance. In this work, an impedimetric immunosensor for ochratoxin A (OTA) detection, a common toxic botanical contaminant, was developed via the immobilization of anti-OTA antibody on bovine serum albumin modified gold electrodes. A four-step reaction protocol was tested to modify the gold electrode and obtain the sensing substrate. All the steps of the immunosensor elaboration and also the immunochemical reaction between surface-bound antibody and ochratoxin A were analyzed using cyclic voltammetry and electrochemical impedance spectroscopy. Modification of the impedance due to the specific antigen-antibody reaction at immunosensor surface, was used in order to detect ochratoxin A. Linear proportionality of the charge transfer resistance to the concentration of OTA allows ochratoxin A detection in the range of 2.5–100 ng/mL.

Functionalized Antimicrobial Composite Thin Films Printing for Stainless Steel Implant Coatings

In this work we try to address the large interest existing nowadays in the better understanding of the interaction between microbial biofilms and metallic implants. Our aimed was to identify a new preventive strategy to control drug release, biofilm formation and contamination of medical devices with microbes. The transfer and printing of novel bioactive glass-polymer-antibiotic composites by Matrix-Assisted Pulsed Laser Evaporation into uniform thin films onto 316 L stainless steel substrates of the type used in implants are reported. The targets were prepared by freezing in liquid nitrogen mixtures containing polymer and antibiotic reinforced with bioglass powder. The cryogenic targets were submitted to multipulse evaporation by irradiation with an UV KrF* (λ = 248 nm, τFWHM ≤ 25 ns) excimer laser source. The prepared structures were analyzed by infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and profilometry, before and after immersion in physiological fluids. The bioactivity and the release of the antibiotic have been evaluated. We showed that the incorporated antibiotic underwent a gradually dissolution in physiological fluids thus supporting a high local treatment efficiency. Electrochemical measurements including linear sweep voltammetry and impedance spectroscopy studies were carried out to investigate the corrosion resistance of the coatings in physiological environments. The in vitro biocompatibility assay using the MG63 mammalian cell line revealed that the obtained nanostructured composite films are non-cytotoxic. The antimicrobial effect of the coatings was tested against Staphylococcus aureus and Escherichia coli strains, usually present in implant-associated infections. An anti-biofilm activity was evidenced, stronger against E. coli than the S. aureus strain. The results proved that the applied method allows for the fabrication of implantable biomaterials which shield metal ion release and possess increased biocompatibility and resistance to microbial colonization and biofilm growth.

Evaluation of Ag containing hydroxyapatite coatings to the Candida albicans infection

In this research work, the synthesis of Ag doped hydroxyapatite coatings for dental or orthopedic implants was performed. The main goal was to determine the influence of Ag content on the roughness and antimicrobial performance of the prepared thin films. The films were deposited on Ti6Al4V alloy by means of RF magnetron sputtering. Those coatings were characterized by X-ray diffraction (XRD) and 3D surface profilometry. The antifungal activity after 1 and 7days of culture was evaluated in the presence of Candida albicans (ATCC - 10231). The increase of Ag content increased roughness and reduced the antifungal activity. The results showed that the Ag doped hydroxyapatite coatings can be a potential solution for the improvement of the antifungal activities of Ti based alloy.

Polymer-Bioglass Composite Coatings: A Promising Alternative For Advanced Biomedical Implants

Human bone can easily regenerate in normal conditions, so in case of fractures some support devices are used to take the load from the new forming bone. However, in case of diseases, ageing and large traumas, the bone has to be helped to regenerate. Usually, large bone defects are filled with natural material from a donor site from the same patient (‘‘autografting”). Unfortunately the transplantable bone is limited and the procedure requires the extension of the operating site (Lahav et al., 2006). The concept of an artificial device able to help human parts to regenerate or to replace entirely one of the body functions, stimulated numerous research teams around the globe to test materials and combinations of materials aiming towards the “holly grail” of biocompatibility: the biomimetism. There are evidences that prove early tests on bone repair using metal parts, dating from antiquity (Bliquez, 1996). Up to present time, metals have been the elements of choice for manufacturing implants or prostheses in various shapes and dimensions. Tests and clinic reports have all agreed in time, that the best metal for such devices is Ti (Emsley, 2001). It is bio tolerated by the human body and it has a low density and mechanical properties that do not negatively affect the bone (Oshida, 2006). Orthopedics as a medicine branch does not consider bio tolerated devices as satisfactory. The general aim of an orthopedic device is to stimulate the bone to regenerate, in other words it has to be bioactive. Ceramic materials made of calcium phosphates (CaP) in various formulas, pure or doped have been extensively studied in literature for their resemblance to the mineral part of the bone (Leon & Jansen, 2010). Because ceramics brittle when submitted to high tensions, devices made completely out of these materials are not convenient. The common consensus is to use for the bulk implant metals as main components, covered by a very thin and adherent ceramic layer, thus making the surface bioactive (Park, 2008). This chapter is dedicated to bioactive glasses (BG), “intelligent materials” superior in bioactivity to CaP, made of various metal oxide combinations. They change their composition in vivo after prolonged contact with body fluids, transforming in an equivalent of the mineral bone (Hench & Wilson, 1993).

Fractional adaptive control for a fractional - order insuline - glucose dynamic model

A new approach to the blood glucose concentration control problem is investigated in this paper. The solution implies the use of fractional-order calculus both for the plants model and for the controller. A fractional-order model of the insulin-glucose system is derived from the well-known minimal model, by replacing the integer derivatives with fractional ones. Next, fractional-order calculus is used to extend the conventional model reference adaptive control, namely by using a fractional-order adjustment rule for the controllers parameters. The controllers design procedure is detailed. Simulations of the proposed control system show the performance in reducing the blood glucose concentration when meal glucose disturbances are considered.

Body burden of toxic metals and rare earth elements in non-smokers, cigarette smokers and electronic cigarette users

ABSTRACT Smoking is considered an important source for inorganic elements, most of them toxic for human health. During the last years, there has been a significant increase in the use of e‐cigarettes, although the role of them as source of inorganic elements has not been well established. A cross‐sectional study including a total of 150 subjects from Brasov (Romania), divided into three groups (non‐smokers, cigarette smokers and electronic cigarettes smokers) were recruited to disclose the role of smoking on the human exposure to inorganic elements. Concentration of 42 elements, including trace elements, elements in the ATSDRs priority pollutant list and rare earth elements (REE) were measured by ICP‐MS in the blood serum of participants. Cigarette smokers showed the highest levels of copper, molybdenum, zinc, antimony, and strontium. Electronic cigarette (e‐cigarette) users presented the highest concentrations of selenium, silver, and vanadium. Beryllium, europium and lanthanides were detected more frequently among e‐cigarette users (20.6%, 23.5%, and 14.7%) than in cigarette smokers (1.7%, 19.0%, and 12.1%, respectively); and the number of detected REE was also higher among e‐cigarette users (11.8% of them showed more than 10 different elements). Serum levels of cerium and erbium increased as the duration of the use of e‐cigarettes was longer. We have found that smoking is mainly a source of heavy metals while the use of e‐cigarettes is a potential source of REE. However, these elements were detected at low concentrations. HighlightsThe role of smoking as a source for 42 inorganic element intakes was explored.The exposure levels of non‐smoker, cigarette smokers and e‐cigarette users was compared.Cigarette smokers showed the highest levels of Cu, Mo, Zn, Sb, and Sr.E‐cigarettes users presented the highest concentrations of Se, Ag, and V.Be, Eu and La were detected more frequently among e‐cigarette users.

Study of combined photovoltaic cell/thermoelectric element/solar collector in medium concentrated light

The performance of the hybrid structures PV/TEG/STC which consist of photovoltaic cells PV, thermoelectric elements TEG and solar collector STC is studied in this paper function of different levels of illumination from 30 suns to 130 suns (1 sun = 1000 W/m2). The concentrated light is obtained using a solar simulator with four parabolic xenon lamps and an optical mixer to ensure the quasi homogenous illumination of the hybrid system. The important parameters of the photovoltaic cells and of the thermoelectric generators are determined using the current-voltage characteristics. The measurements and control are realized using the NI-cRIO platform and the software is developed in LabVIEW.

Accelerated Life Test for Photovoltaic Cells Using Concentrated Light

This paper presents a new method developed to significantly reduce the necessary time for the ageing tests for different types of photovoltaic cells. Two ageing factors have been applied to the photovoltaic cells: the concentrated light and the temperature. The maximum power of the photovoltaic cells was monitored during the ageing process. The electrical dc and ac parameters of the photovoltaic cells were measured and analyzed at 1 sun irradiance, before and after the test stress. During the test, two photovoltaic cells are kept at maximum power point and the other two are kept at open circuit voltage point. The method is validated through the results obtained for the monocrystalline silicon solar cell.