Olga Korostynska

An overview of foodborne pathogen detection: In the perspective of biosensors

Food safety is a global health goal and the foodborne diseases take a major crisis on health. Therefore, detection of microbial pathogens in food is the solution to the prevention and recognition of problems related to health and safety. For this reason, a comprehensive literature survey has been carried out aiming to give an overview in the field of foodborne pathogen detection. Conventional and standard bacterial detection methods such as culture and colony counting methods, immunology-based methods and polymerase chain reaction based methods, may take up to several hours or even a few days to yield an answer. Obviously this is inadequate, and recently many researchers are focusing towards the progress of rapid methods. Although new technologies like biosensors show potential approaches, further research and development is essential before biosensors become a real and reliable choice. New bio-molecular techniques for food pathogen detection are being developed to improve the biosensor characteristics such as sensitivity and selectivity, also which is rapid, reliable, effective and suitable for in situ analysis. This paper not only offers an overview in the area of microbial pathogen detection but it also describes the conventional methods, analytical techniques and recent developments in food pathogen detection, identification and quantification, with an emphasis on biosensors.

Review on State-of-the-art in Polymer Based pH Sensors

This paper reviews current state-of-the-art methods of measuring pH levels that are based on polymer materials. These include polymer-coated fibre optic sensors, devices with electrodes modified with pH-sensitive polymers, fluorescent pH indicators, potentiometric pH sensors as well as sensors that use combinatory approach for ion concentration monitoring.

Conducting Polymers and Their Applications to Biosensors: Emphasizing on Foodborne Pathogen Detection

Detection of microbial pathogens in food is the solution to the prevention and recognition of problems related to health and safety. New biomolecular approaches for foodborne pathogen detection are being developed to improve the biosensor characteristics such as sensitivity and selectivity, also which is rapid, reliable, cost-effective, and suitable for in situ analysis. Recently, conducting polymers have drawn attention in the development of biosensors. The electrically conducting polymers have numerous features, which allow them to act as excellent materials for immobilization of biomolecules. Also, their unique properties make them appealing alternatives for specific materials currently employed for the fabrication of biosensors. Therefore, this paper presents a comprehensive literature review detailing the salient features of conducting polymers and their application to biosensors with an emphasis on foodborne pathogen detection.

Review Paper: Materials and Techniques for In Vivo pH Monitoring

Advances in semiconductor sensor technology, medical diagnostics, and health care needs a rapid boost in research into novel miniaturized pH sensors, which can be used in vivo for continuous patient monitoring. Requirements for the in vivo sensor are materials biocompatibility, high measurement precision, a response time of an order of less than seconds, and the possibility of continuous 24-h monitoring. Monitoring of the pH values is important in the study of tissue metabolism, in neurophysiology, cancer diagnostics, and so forth. Muscle pH can be used to triage and help treat trauma victims as well as to indicate poor peripheral blood flow in diabetic patients. Clearly, to avoid infection and spread of diseases, all in vivo monitoring devices should be single-use/disposable, which puts strict requirement on their price. This paper reviews the wide range of methods and materials used for in vivo measurement of pH levels, such as using the optical fibers, pH-sensitive polymers, ion-sensitive field effect transistors, near infrared spectroscopy, nuclear magnetic resonance, and fluorescent pH indicators.

pH Sensitivity of Novel PANI/PVB/PS3 Composite Films.

This paper reports on the results from the investigation into the pH sensitivity of novel PANI/PVB/PS3 composite films. The conductimetric sensing mode was chosen as it is one of the most promising alternatives to the mainstream pH-sensing methods and it is the least investigated due to the popularity of other approaches. The films were deposited using both screen-printing and a drop-coating method. It was found that the best response to pH was obtained from the screen-printed thick films, which demonstrated a change in conductance by as much as three orders of magnitude over the pH range pH2-pH11. The devices exhibited a stable response over 96 hours of operation. Several films were immersed in buffer solutions of different pH values for 96 hours and these were then investigated using XPS. The resulting N 1s spectra for the various films confirmed that the change in conductance was due to deprotonation of the PANI polymer backbone. SEM and Profilometry were also undertaken and showed that no considerable changes in the morphology of the films took place and that the films did not swell or contract due to exposure to test solutions.

Microwave sensors for the non-invasive monitoring of industrial and medical applications

Purpose – This paper aims to discuss the general principles behind the microwave sensing and demonstrates the potential of cavity microwave resonator device in real-time monitoring for: environmental monitoring with the focus on wastewater pollution, a system for oil/gas/water content evaluation in a dynamic pipeline, a system for real-time determination of bacteria concentration and a method for non-invasive glucose determination. Design/methodology/approach – Microwave sensing is a rapidly developing technology which has been successfully used for various industrial applications including water level measurements, material moisture content, in construction industry for non-invasive evaluation of structures and even in the healthcare industry for non-invasive real-time monitoring of glucose in diabetic patients. Novel microwave cavities designed and tested for specific applications are presented. Findings – The paper provides experimental results of testing the novel microwave sensing systems in a range ...

Glucose monitoring using electromagnetic waves and microsensor with interdigitated electrodes

A microscale glucose sensor for biomedical applications was fabricated utilizing the enzyme glucose oxidase and the polymer poly(o-phenylenediamine). A solution containing the enzyme immobilized in the polymer was deposited on interdigitated microelectrodes to form sensor arrays. This was achieved using novel nanopatterning technology offered by BioForce NanoeNabler™. Samples containing different concentrations of glucose were applied to the sensor while the system was being monitored for variances in either current or conductance. The resulting changes in the electrical characteristics of the sensor monitored in real time were found to be proportional to the different concentrations of glucose applied. It is strongly believed that the size reduction of the sensor to a few microns described in this paper creates new opportunities in the areas of chemical and biological sensor development.

/spl gamma/-radiation dosimetry using screen printed nickel oxide thick films

Thick films of nickel oxide (NiO) were investigated for /spl gamma/-radiation dosimetry purposes. Samples were fabricated using the thick film screen printing technique. Absorption spectra for NiO films were recorded and the values of the optical band gap for as-printed, irradiated and annealed films were calculated. It was found that the optical band gap value decreased as the radiation dose was increased. Samples with an Ag-NiO-Ag sandwich structure were exposed to a /sup 60/Co /spl gamma/-radiation source at a dose rate of 6 Gy/min. The relative change in current increased linearly with increased dosage up to 720 Gy. The I-V characteristics indicated a Poole-Frenkel conduction mechanism. It was found that annealing restored both the electrical and the optical properties of the samples.

Gamma radiation dosimetry using tellurium dioxide thin film structures

Thin films of tellurium dioxide (TeO/sub 2/) were investigated for /spl gamma/-radiation dosimetry purposes. Samples were fabricated using thin film vapour deposition technique. Thin films of TeO/sub 2/ were exposed to a /sup 60/Co /spl gamma/-radiation source at a dose rate of 6 Gy/min at room temperature. Absorption spectra for TeO/sub 2/ films were recorded and the values of the optical band gap and energies of the localized states for as-deposited and /spl gamma/-irradiated samples were calculated. It was found that the optical band gap values were decreased as the radiation dose was increased. Samples with electrical contacts having a planar structure showed a linear increase in current values with the increase in radiation dose up to a certain dose level. The observed changes in both the optical and the electrical properties suggest that TeO/sub 2/ thin film may be considered as an effective material for room temperature real time /spl gamma/-radiation dosimetry.

Thin and thick films of metal oxides and metal phthalocyanines as gamma radiation dosimeters

Numerous efforts were devoted to investigating the influence of radiation on metal oxides and polymer materials for dosimetry applications. Metal oxides, such as NiO, LaFeO/sub 3/, CeO/sub 2/, TeO/sub 2/, In/sub 2/O/sub 3/, SiO and MnO, and polymers, such as CuPc, NiPc, MnPc and CoPc, were used as the active constituents in the fabrication of /spl gamma/-radiation sensors. Thin and thick film devices were made in various topologies to form resistors, capacitors, pn-junctions and transistors. It was found that the properties of the active films (and, hence, their sensitivity to radiation) could be controlled by doping their constituent materials with carbon and mixing them in different proportions. The /sup 60/Co and /sup 137/Cs sources were used to expose the samples to /spl gamma/-radiation. Current-voltage characteristics, optical absorption spectra, Raman spectra, SEM and XRD measurements were recorded for the samples after each exposure procedure and values of radiation damage were estimated. Thin film devices were found to be more sensitive to radiation than their thick film counterparts. Annealing was used to restore the properties of thick film devices after they were damaged with radiation. Thick films could be therefore reused on a repeatable basis, but thin film devices could not, as the heat treatments necessary for annealing were found to cause diffusion of the electrode materials. In this work, the possibility of fabricating a device that would satisfy the requirement of a particular application, such as sensitivity to /spl gamma/-radiation and working dose region, was experimentally demonstrated. Based on the findings, these devices were found to provide a cost-effective alternative for room temperature real time /spl gamma/-radiation dosimeter applications.