[Phenomena of transport in polymeric systems through the release of drugs].
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Biological Transport↗
Biomedical subjects
E Drioli
Publications and source records attributed to E Drioli.
Characterization and control of an immobilized allosteric enzyme system.
Both immobilization techniques described in this work seem appropriate for this allosteric enzyme. However, the kinetic behavior of the dCMP deaminase trapped in a protein membrane is markedly different from that observed with the enzyme in solution and with the enzyme gelled on an artificial membrane. The enzyme, in fact, in all instances loses its cooperative action toward the substrate and even the allosteric ligands, or they do not affect the activity, or it behaves in a completely different way. In particular, dTTP seems to behave as a noncompetitive inhibitor. These effects can be attributed either to the freezing of the enzyme in one of its conformations or, more generally, to the effect of physical constraints and diffusional resistances. Further studies are in progress to distinguish between the contributions of each one of these phenomena to the kinetic behavior of the enzyme.
Albumins↗
Thermophylic microbial cells immobilized in cellulose acetate membranes.
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Bacteria↗
The influence of polymeric membrane surface free energy on cell metabolic functions.
In membrane bioartificial organs using isolated cells, polymeric semipermeable membranes are used as immunoselective barriers, means for cell oxygenation and also as substrata for adhesion of anchorage-dependent cells. The selection of cytocompatible membranes that promote in vitro cell adhesion and function could be dependent on its membrane properties. In this study we investigated the physicochemical aspects of the interaction between the membrane and mammalian cells in order to provide guidelines to the selection of cytocompatible membranes. We evaluated the metabolic behavior of isolated liver cells cultured on various polymeric membranes such as the ones modified by protein adsorption. The physico-chemical properties of the membranes were characterized by contact angle measurements. The surface free energy of membranes and their different parameters acid (gamma+), base (gamma-) and Lifshitz-van der Waals (gammaLW) were calculated according to Good-van Oss's model. The adsorption of protein modified markedly both contact angle and membrane surface tension. In particular, membrane surface free energy decreased drastically with increased water contact angle. For each investigated membrane we observed that liver specific functions of cells improve on hydrophilic membrane surfaces. For all investigated membranes the rate of ammonia elimination increased with increasing of membrane surface free energy.
Journal Article↗
Preparation and characterisation of membranes with entrapped TiO2 and preliminary photocatalytic tests.
The possibility of entrapping polycrystalline TiO2 in a polymeric support, in order to couple the two unit operations, i.e. ultrafiltration and photodegradation of organic pollutants in aqueous solutions, was investigated. To this aim, polymeric membranes for ultrafiltration with entrapped TiO2 were prepared, characterised and tested. The polymeric support chosen was commercial polysulfone (PSf). The membrane preparation was carried out with the technique referred to as phase inversion. A three-component system, with a polymer, a solvent and a non-solvent was used. The best operative conditions were determined in order to obtain the desired membrane morphology. Permeability measurements and photostability tests were also carried out by using a system under pressure. Finally, a preliminary investigation was performed in order to evaluate the photocatalytic activity of the membranes with entrapped TiO2 for the oxidation of 4-nitrophenol as a model molecule in aqueous solutions.
Catalysis↗
Photocatalytic membrane processes for degradation of various types of organic pollutants and micropollutants in water.
Degradation tests in a photocatalytic membrane system have been carried out using TiO2 (Degussa P25) as catalyst and humic acid, organic dyes, 4-nitrophenol as pollutants. The influence of UV radiation and initial concentration of pollutant on the photodegradation rate were investigated in discontinuous and continuous systems. Experimental results showed that it is possible to obtain an efficient photocatalytic membrane process, but various parameters (e.g. pH) should be optimised to obtain high reaction rate and high membrane rejection of pollutants and their by-products.
Catalysis↗
Rapid determination of tannins in tanning baths by adaptation of BSA method.
A rapid and reproducible method for the determination of tannins in vegetable tanning baths is proposed as a modification of the BSA method for grain tannins existing in literature. The protein BSA was used instead of leather powder employed in the Filter Method, which is adopted in Italy and various others countries of Central Europe. In this rapid method the tannin contents is determined by means a spectrophotometric reading and not by means a gravimetric analysis of the Filter Method. The BSA method, which belongs to mixed methods (which use both precipitation and complexation of tannins), consists of selective precipitation of tannin from a solution containing also non tannins by BSA, the dissolution of precipitate and the quantification of free tannin amount by its complexation with Fe(III) in hydrochloric solutions. The absorbance values, read at 522 nm, have been expressed in terms of tannic acid concentration by using a calibration curve made with standard solutions of tannic acid; these have been correlated with the results obtained by using the Filter Method.
Absorption↗
Enzymatic hydrolysis of DNA using a membrane bioreactor.
Aim of this work was a kinetic study of the deoxyribonuclease I (E.C. 3.1.21.1.) reaction in several conditions. Optimal reaction conditions with enzyme free in solution were determined. DNase activity was studied as function of several parameters such as pH, enzyme concentration, substrate concentration, cofactor concentration. The Km value of the free enzyme was also determined. Subsequently, the possibility to carry out the reaction in systems in which the enzyme was immobilized on the inner surface of the polymeric membranes was evaluated and realized. Experimental procedures, in these new conditions, permitted to determine the mass of immobilized enzyme and the percentage of the reaction product recovery. Results showed that the immobilization procedure determines a decay of the initial activity of enzyme, but there is an important increase of enzyme stability.
Animals↗