Giovanni Merola

Agent orange herbicides, organophosphate and triazinic pesticides analysis in olive oil and industrial oil mill waste effluents using new organic phase immunosensors.

New immunosensors working in organic solvent mixtures (OPIEs) for the analysis of traces of different pesticides (triazinic, organophosphates and chlorurates) present in hydrophobic matrices such as olive oil were developed and tested. A Clark electrode was used as transducer and peroxidase enzyme as marker. The competitive process took place in a chloroform-hexane 50% (V/V) mixture, while the subsequent enzymatic final measurement was performed in decane and using tert-butylhydroperoxide as substrate of the enzymatic reaction. A linear response of between about 10nM and 5.0μM was usually obtained in the presence of olive oil. Recovery tests were carried out in commercial or artisanal extra virgin olive oil. Traces of pesticides were also checked in the oily matrix, in pomace and mill wastewaters from an industrial oil mill. Immunosensors show good selectivity and satisfactory precision and recovery tests performed in olive oil gave excellent results.

Further development on DMFC device used for analytical purpose: real applications in the pharmaceutical field and possible in biological fluids.

AbstractThe analytical research devoted to the utilization of the direct methanol fuel cell (DMFC) for analytical purposes has been continued. The research reported in this paper concerns two points, one of which was the possibility of improving the features, from the analytical point of view, of a catalytic fuel cell for methanol and ethanol, by introducing an enzyme, immobilized into a dialysis membrane small bag, in the anodic area of the fuel cell. This objective has been fully achieved, particularly using the enzyme alcohol dehydrogenase, which has increased the sensitivity of the method and reduced dramatically the response time of the cell. The second point concerned the opportunity to determine two particular antibiotics having an alcohol functional group in their molecule, that is, imipenem and chloramphenicol. Also, this goal has been reached, even if the sensitivity of the method is not so high. Graphical abstractImipenem and Chloramphenicol determination using the DMFC and Ethanol determination using the enzymatic DMFC

Comparison between a Direct-Flow SPR Immunosensor for Ampicillin and a Competitive Conventional Amperometric Device: Analytical Features and Possible Applications to Real Samples

In this research, we developed a direct-flow surface plasmon resonance (SPR) immunosensor for ampicillin to perform direct, simple, and fast measurements of this important antibiotic. In order to better evaluate the performance, it was compared with a conventional amperometric immunosensor, working with a competitive format with the aim of finding out experimental real advantages and disadvantages of two respective methods. Results showed that certain analytical features of the new SPR immunodevice, such as the lower limit of detection (LOD) value and the width of the linear range, are poorer than those of a conventional amperometric immunosensor, which adversely affects the application to samples such as natural waters. On the other hand, the SPR immunosensor was more selective to ampicillin, and measurements were more easily and quickly attained compared to those performed with the conventional competitive immunosensor.

Ampicillin Measurement Using Flow SPR Immunosensor and Comparison with Classical Amperometric Immunosensor

An analytical comparison of a flow SPR immunosensor method and a conventional amperometric immunosensor has been carried out. Different formats were used, respectively, main analytical data have been checked and affinity constant values evaluated and compared.

Miniaturized bio-sensor for environment monitoring in manned space mission

The aim of our research is to investigate about the respiratory activity (thermodynamics and kinetics) of eukaryotic cells in micro-gravity condition. Cells used for the experiment are saccharomyces cerevisiae cells (common yeast). By now yeast cells, due to their similarity to human cells, are used to detect the presence of pollution, or harmful particles on food or liquids. As well as human beings, yeast cells are sensitive to pollutant, therefore the detection of such substances is based upon a measurement of yeast state of health, in terms of metabolic activity. The most common way to measure yeast metabolic activity is by “respirometry”: measurement of oxygen concentration change over time in a solution containing yeast, glucose and the investigated substance. Yeast cells, while “breathing”, produce a decrease of oxygen concentration. The steady state value, reached few minutes after the yeast injection into the glucose solution, is an indicator of the metabolic activity. The purpose of our study is to use a miniaturized device as an environmental sensor for future manned missions. For this aim has been necessary to miniaturize a whole respirometric lab and make it fully stand alone, than compare the behavior of yeast cells in a microgravity medium to the behavior on Earth conditions. The “space laboratory” is less than 1dm^3 (600g) and contains 4 identical experiments based on biosensors. In this paper are described the chemical and engineering processes (included qualification tests) needed for a miniaturization of 600 times less.

Three Different Sensor Methods for Methanol and Ethanol Determination

Three different sensor-based methods for methanol and ethanol determination have been developed. Two of these consist of different enzyme electrodes using respectively alcohol oxidase or catalase immobilized in a k-Carrageenan gel layer overlapping an amperometric gaseous diffusion Clark type oxygen electrode. The third sensor is a small catalytic ‘fuel cell’ originally constructed for the purpose of obtaining energy from methanol or ethanol but now adapted for analytical purposes. The linearity ranges and LOD values for methanol and ethanol analysis obtained so far from three devices are optimized and compared.

Respirometric Tests on Yeast Cells Located in a Small Satellite System

The primary aim of the research is to investigate about the respiratory activity (thermodynamics and kinetics) of eukaryotic cells in micro gravity medium. This information can be precious both with reference to human activity in the same conditions and to possible applications to environmental sensing by respirometry. In a space platform, one of the human main activities is surely respiration as strictly related to life conditions. When breathing is not permitted, life expires. What happens to this function in a small satellite system? How do the specific conditions affect the capacity of oxygen uptake and the shape of a respiration curve? In this presentation we describe a research aiming to study the behavior of a well common respirometric system, Saccharomyces Cerevisiae yeast cells when located within a closed system positioned inside a small satellite system. More the consequently needed miniaturization of the Clark electrode to amperometrically determine oxygen brings to a further reason of uncertainness related to the high current density and consequent polarization. Some problems were faced such as the aggregation of the cells able to close the circuit where solution is flowing in the experimental system, the formation of gaseous bubbles going to constitute cause of increasing electric resistance, the rigorous stability of the applied tension, the miniaturization of reactor passed from a mean 20 mL model in normal lab to 1 mL and less model when located in a small satellite system.