Biomedical subjects

M Tomassetti

Publications and source records attributed to M Tomassetti.

At least 19 recordsLinked to original sources

PubMed2006

Salicylic acid determination in cow urine and drugs using a bienzymatic sensor.

An enzymatic biosensor was developed for salicylic acid (salicylate ion) determined using a Clark type gas diffusion electrode and two enzymes (tyrosinase and salicylate hydroxylase) entrapped in a cellulose triacetate membrane. After optimization, the method was applied to the determination of salicylic acid in cow urine. Relatively good recoveries were achieved, between about 83% and 109%, using the calibration curve, and acceptable precision (R.S.D. about 8%). The method is now being tested for the determination of salicylic acid contained in commercially available drug specialities or galenic products. So far agreement with nominal values has been found to be between 75% and 110% with a R.S.D. of less than 8%.

Animals↗

PubMed2005

Tyrosinase inhibition organic phase biosensor for triazinic and benzotriazinic pesticide analysis (part two).

Several triazine pesticides, such as atrazine, are much more soluble in several organic solvents, such as chloroform, than in water. Our recent research was aimed at analyzing this class of pesticides using tyrosinase OPEE (organic phase enzyme electrodes), exploiting their inhibiting action on the tyrosinase enzyme when operating in water-saturated chloroform medium. In this work we studied the response of a tyrosinase inhibition enzyme sensor to several triazinic (simazine, propazine, terbuthylazine) and benzotriazinic (azinphos-ethyl and azinphos-methyl) pesticides (LOD=0.5x10(-9) mol l(-1)). Recovery trials were also performed in vegetal matrixes (corn, barley, lentils). Lastly, the effect of the solvent (chloroform or water) on the inhibition process was investigated via Hill's equation and the diffusion of analyte from the solvent to the enzyme membrane.

Biosensing Techniques↗

PubMed2004

Thermal analysis study of the interactions between acetaminophen and excipients in solid dosage forms and in some binary mixtures.

Thermogravimetry (TG) and differential scanning calorimetry (DSC) were used to assess the compatibility between acetaminophen (Ac) and some excipients (polyvinylpyrrolidone (P), magnesium stearate (M), citric acid (C), aspartame (As), mannitol (Mn), cellulose (Cll) and starch (S)) in several of the more commercially available pharmaceutical formulations and in solid binary mixtures. The present study compared thermodynamic data on acetaminophen melting and vaporization processes of pure acetaminophen with those found for several solid mixtures and in some commercially available acetaminophen-based dosage forms. Appreciable modifications occur only for solid mixtures with high content of excipient. Acetaminophen-based dosage forms and its solid binary mixtures usually show "additivity" of calorimetric peaks number of pure components in their calorimetric curve profiles, thus revealing a good thermoanalytical compatibility between acetaminophen and the excipients examined, except for samples containing appreciable content of mannitol.

Acetaminophen↗

PubMed2004

Comparison of fluorimetric, voltammetric and biosensor methods for the determination of total antioxidant capacity of drug products containing acetylsalicylic acid.

Antioxidant capacity of several drug specialities containing as mean component acetylsalicylic acid were experimentally evaluated using an enzymatic electrode, recently developed by the present authors, based on superoxide dismutase (SOD) enzyme. The precision of this method of analysis was found to be good (for drug samples RSD < or = 5%). The results were also compared with those ones by a traditional spectrofluorimetric method and by two other methods, respectively, based on cyclic and pulsed voltammetry, recently trialled by the present authors.

Antioxidants↗

PubMed2004

Biosensors for determination of total antioxidant capacity of phytotherapeutic integrators: comparison with other spectrophotometric, fluorimetric and voltammetric methods.

Enzymatic electrodes based on superoxide dismutase (SOD) biosensors, working both in aqueous and non-aqueous solutions, recently developed by the present authors, were used to experimentally evaluate the antioxidant capacity of several phytotherapeutic diet integrators. The precision of this method of analysis was found to be reasonable (R. S. D. < or = 10%). The results were also compared with those obtained using a traditional spectrophotometric method as well as a spectrofluorimetric method described in literature. Lastly, the comparison was extended to another method based on cyclic voltammetry currently being trialled by the present authors.

Antioxidants↗

PubMed2004

Determination of choline containing phospholipids in serum, bile and amniotic fluids by the derivative enzymatic-spectrophotometric method.

A comparison was performed of the analytical results obtained by applying a well-known enzymatic-spectrophotometric method for the determination of choline containing phospholipids in biological human fluids (sera, bile and amniotic fluids) following the standard procedure method, or else using the first or second derivative methods. In terms of result reproducibility the comparison was extended to include also a biosensor-based method developed in recent years by the present authors. Some advantages are associated with using the first derivative method in the case of serum samples containing blood traces, especially via the 'Gran's plot' method.

Amniotic Fluid↗

PubMed2004

Biosensors for determination of total and natural antioxidant capacity of red and white wines: comparison with other spectrophotometric and fluorimetric methods.

Research was carried out to experimentally evaluate the antioxidant capacity of several red and white wines using a superoxide dismutase (SOD) biosensor recently developed by the present authors. Measurements were performed by comparing the biosensor response to increasing concentration of the superoxide radical produced in solution by the xanthine/xanthine oxidase system, both in the presence and absence of the test sample.The results were compared with those of two traditional spectrophotometric methods and of a spectrofluorimetric method described in literature.Lastly, also the polyphenol, sulfite and ascorbic acid contents of the different wine samples examined were measured using a tyrosinase biosensor, a sulfite oxidase biosensor and an ascorbate oxidase biosensor, respectively.

Antioxidants↗

PubMed2003

Determination of the antioxidant capacity of samples of different types of tea, or of beverages based on tea or other herbal products, using a superoxide dismutase biosensor.

Research was performed to experimentally evaluate the antioxidant capacity of different plant products sold by herbalists (ginger, dog rose, ginseng and camomile) and of several types of tea (ordinary tea, green tea, detheinated tea, lemon and peach flavoured tea) using a superoxide dismutase (SOD) biosensor recently developed by the present authors. Measurements were carried out by comparing biosensor response to the superoxide radical produced in solution using the xanthine-xanthine oxidase system, both in the presence and absence of the antioxidant sample considered. Precision of antioxidant capacity measures for herbal products and for non diluted samples was good, generally with a R.S.D.%< or =10% and a LOD value about 0.1 for relative antioxidant capacity. Also a "pool" of polyphenols from different tea samples was measured using a tyrosinase biosensor (LOD approximately 2 microM).

Antioxidants↗

PubMed2003

Determination of hydrogen peroxide in disinfectant solutions using a biosensor with two antagonist enzymes.

The development and characterisation of a new biosensor for hydroperoxides is described, which is obtained by combining an oxygen gas diffusion amperometric electrode and two immobilized enzymes (peroxidase and tyrosinase) working in parallel and competing for the same substrate (catechol). The response of the biosensor to several hydroperoxides was investigated (LOD=0.5.10(-4) M for hydrogen peroxide). It was experimentally found that the biosensor is able to respond also to aqueous solutions of ionic peroxides (LOD=0.2.10(-4) M for potassium peroxidisulphate). The biosensor was applied to the determination of the hydrogen peroxide content of pharmaceutical products, i.e. aqueous disinfectant solutions (RSD% < or =0.5; recoveries by standard addition method between 96.0 and 98.5%).

Biosensing Techniques↗

PubMed2003

Determination of antioxidant properties of aromatic herbs, olives and fresh fruit using an enzymatic sensor.

The aim was to experimentally evaluate the antioxidant capacity of different fresh aromatic herbs (field balm, marjoram, parsley, rosemary, sage, sweet basil), several varieties of olives from Central Italy ('Carboncello', 'Rosciolo', 'Olivastro', 'Coratello', 'Leccino', 'Frantoio') and several types of fresh fruit (apple, apricot, banana, cherry, fig, grape, medlar, melon, peach, pear, pineapple, plum, water melon, yellow plum) using a superoxide dismutase (SOD) biosensor developed by the present authors. Measurements were carried out by comparing the biosensor response to the concentration of superoxide radical produced in solution using a xanthine/xanthine oxidase system in the presence and absence of the antioxidant sample considered. Tests carried out on different samples of fruit and aromatic herbs showed that the homogenised samples had better antioxidant properties than the centrifuged ones (obtained by centrifuging the homogenate), which sometimes gave extremely low antioxidant capacity values. The reliability of the proposed method was checked by comparing the trend of some experimental results found using the SOD biosensor with those reported in the literature obtained using the classic (ORAC) method. The precision of this method of analysis was found to be good for samples of aromatic herbs (RSD% <or=8%), acceptable for homogenised fruit samples (RSD% <or=13%) and less good for homogenised and centrifuged samples (RSD% <or=20%).

Antioxidants↗

PubMed2002

Kinetic analysis of thermal decomposition for penicillin sodium salts: model-fitting and model-free methods.

A kinetic study on decomposition processes of some penicillin salts was carried out. Both isothermal and dynamic thermogravimetric curves were used. As expected by their complex structures, several steps with different energies were involved in decomposition processes. Model-fitting and -free kinetic approaches were applied to nonisothermal and isothermal data. The kinetic triplet (f(alpha),A and E(a)) related to model-fitting method that defines a single step reaction resulted to be at variance with the multi-step nature of salts-decomposition. The model-free approach represented by the isothermal and nonisothermal isoconversional methods, gave different dependencies of the activation energy on the extent of conversion. The complex nature of the multi-step process of the studied compounds was more easily revealed using a broader temperature range in nonisothermal isoconversional method. The failure in the model-fitting method did not allow calculating shelf life and half-life times.

Ampicillin↗

PubMed2002

Determination of lecithin drug specialties and diet integrators; by means of first or second derivative enzymatic-spectrophotometric analysis.

The possibility has been investigated of applying derivative analysis to a classical enzymatic-spectrophotometric method for lecithin determination for the purpose of developing an analytical direct method that does not require long pretreatment of the test sample even in the case of turbid samples. Several samples of drugs and food integrators containing lecithin were thus tested using both the standard and the derivative method and then comparing the results obtained. The RSD% values of measurements on real (food or drugs) samples were always <2.5. Using a first derivative spectrophotometric method, average recovery was always between 102 and 105%.

Alcohol Oxidoreductases↗

PubMed2001

Superoxide dismutase biosensors working in non-aqueous solvent.

Enzymatic electrodes based on superoxide dismutase enzyme were developed. Using the superoxide dismutase enzyme sensor assembled according to the classical model, poor results were obtained. Results were improved by adopting a new way of assembling the biosensor using a cellulose triacetate layer in which the SOD enzyme is entrapped and sandwiched between two gas-permeable membranes, or using a kappa-carrageenan gel layer entrapping the enzyme, sandwiched between an external gas permeable membrane and an internal cellulose acetate membrane, coupled in each case to the oxygen amperometric transducer. Results obtained by applying the newly developed biosensor to assaying hydrophobic compounds showing radical scavenging properties, operating in dimethylsulfoxide, were also satisfactory.

Biosensing Techniques↗

PubMed2001

Evaluation of radical scavenging properties of several plants, fresh or from a herbalist's, using a superoxide dismutase biosensor.

The experimental evaluation of properties of defence against free radicals represents an extremely interesting heuristic and applicational objective. Research was carried out to experimentally evaluate the scavenging properties of several fruits and plants, fresh or from a herbalist's using an amperometric superoxide dismutase (SOD) biosensor recently developed by the present authors. The superoxide radical was produced in solution using the xanthine/xanthine oxidase system; measurements were carried out by comparing biosensor response to superoxide radical both in the presence and absence of the sample considered.

Biosensing Techniques↗

PubMed2001

Thermal stability of disodium and calcium phosphomycin and the effects of the excipients evaluated by thermal analysis.

In the present study, Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) are simultaneously applied to determine the thermal properties of two antibiotic salts, disodium and calcium phosphomycin, used either pure or in association with several excipients. This study was carried out kinetically as well by mathematical elaboration of the TG curves performed according to an isothermal procedure applied at different fixed temperatures. Kinetic parameters showing agreement with those produced by the isothermal method were also obtained by means of a non-isothermal method using a dynamic TG curve alone. The main aims of the work were to provide reliable kinetic parameters (kinetic constant k, activation energy E(a) and pre-exponential factor A) to evaluate the thermal stability of phosphomycin salts in the presence and absence of the excipients generally contained in the phosphomycin-based pharmaceutical forms available on the market, and to obtain information concerning compatibility towards the active components. These kinetic parameters were then used to extrapolate shelf-life and half-life values at room temperature for pure active components in the solid state and for their pharmaceutical derivatives.

Anti-Bacterial Agents↗

PubMed2001

Two OPEEs (organic phase enzyme electrodes) used to check the percentage water content in hydrophobic foods and drugs.

The development and optimization of an analytical method using enzymatic biosensors able to operate in organic solvents [organic phase enzyme electrodes (OPEEs)] for the determination of the water content in food fats (butter, margarine) or pharmaceutical or cosmetic ointments is described. The method is based on the increase in enzymatic activity which is related to the increase in the percentage water content in the organic phase into which the biosensor is dipped. The enzymes used to assemble the biosensors were tyrosinase or catalase, the substrates were phenol or p-cresol and tert-butyl hydroperoxide, respectively, and the organic solvents were acetonitrile or dioxane. A gas diffusion amperometric electrode for oxygen measurement was used as electrochemical transducer. The results were compared with those obtained applying the Karl Fischer method to the same food or drug matrices. The correlations among the two methods proved satisfactory, as the difference in the computed values of water content was never higher than 7%. Also, the precision of measurements was acceptable (RSD < 6%) in all the analyses of real matrices.

Biosensing Techniques↗

PubMed2000

New biosensor for superoxide radical used to evidence molecules of biomedical and pharmaceutical interest having radical scavenging properties.

A superoxide dismutase biosensor was used to determine the antioxidant properties of scavenger molecules and the antiradical activity of healthy and diseased human kidney tissues; this biosensor is based on the use of the enzyme superoxide dismutase (SOD), which is physically entrapped in a kappa-carrageenan gel membrane, and of a transducer consisting of an amperometric hydrogen peroxide electrode. Several compounds with scavenging properties were tested, including some commercial drugs.

Biosensing Techniques↗

PubMed2000

Flow injection analysis of cholic acids in pharmaceutical preparations using a polymeric membrane ISE as detector.

The results reported in this paper regard the setting up of a polymeric membrane ISE that is selective for cholic acids (CA) and able to work in a flow system, especially in flow injection analysis (FIA), based on the exchanger (tetrakisdecylammoniumcholate, TDACh), which has proved effective, is of very simple but suitable structure and is above all easy to synthesise starting from commercially available chemicals. A complete analytical characterisation of the sensor was performed working both in batch conditions and in FIA, using in the latter case a 'wall jet' type of flow cell. The response toward different bile acid sodium salts such as the CA, deoxycholic (DCA), chenodeoxycholic (CDCA), ursodeoxycholic (UDCA), taurocholic (TCA) sodium salts was checked. The application to the analysis of different commercial drugs by FIA was also performed to determine the UDCA or CDCA acid content of several pharmaceutical formulations. Lastly, a preliminary study is presented concerning the use of the investigated electrochemical sensor as high performance liquid chromatography (HPLC) detector.

Cholic Acids↗