Laura Donato

Bio-mimetic sensors based on molecularly imprinted membranes.

An important challenge for scientific research is the production of artificial systems able to mimic the recognition mechanisms occurring at the molecular level in living systems. A valid contribution in this direction resulted from the development of molecular imprinting. By means of this technology, selective molecular recognition sites are introduced in a polymer, thus conferring it bio-mimetic properties. The potential applications of these systems include affinity separations, medical diagnostics, drug delivery, catalysis, etc. Recently, bio-sensing systems using molecularly imprinted membranes, a special form of imprinted polymers, have received the attention of scientists in various fields. In these systems imprinted membranes are used as bio-mimetic recognition elements which are integrated with a transducer component. The direct and rapid determination of an interaction between the recognition element and the target analyte (template) was an encouraging factor for the development of such systems as alternatives to traditional bio-assay methods. Due to their high stability, sensitivity and specificity, bio-mimetic sensors-based membranes are used for environmental, food, and clinical uses. This review deals with the development of molecularly imprinted polymers and their different preparation methods. Referring to the last decades, the application of these membranes as bio-mimetic sensor devices will be also reported.

Study of Fouling Phenomena in Apple Juice Clarification by Enzyme Membrane Reactor

ABSTRACT Membrane separation processes have great potential in the food industry due to their ability to operate in mild conditions and to involve no phase change or chemical agents. The present work is part of a project which investigates the use of integrated membrane processes to produce fruit juices that are additive-free and have a natural, fresh taste. A study to optimize the depectinization and clarification of apple juice by enzyme membrane reactors has been carried out by using laboratory and semipilot scale equipments. The performance of the membrane systems has been investigated in terms of permeate flux and degree of depectinization. The effects of various parameters (transmenbrane pressure, axial flow rate, feed mixture, etc.) on membrane fouling have been evaluated, and the fouling mechanism has been interpreted in terms of complete pore blocking or cake filtration. The permeate flux improved with an increasing enzyme percentage in the feed mixture.

Tyrosinase immobilized on a hydrophobic membrane

Polyvinylidene fluoride (PVDF) membrane surfaces were ad hoc functionalized chemically to make them suitable for enzymatic immobilization. The process was performed by grafting the membrane surface with 1,4‐diaminobutane and subsequently by activating it with glutarhaldehyde. The chemico‐physical properties of the original PVDF membrane and of the modified membranes were studied by infrared spectroscopy, scanning electron microscopy, and static contact angle measurements. The activated membranes were used as a support for covalent immobilization of tyrosinase. The activity of free and immobilized enzyme was studied and compared. The experimental data showing the specific activity of the immobilized enzyme are similar to the value obtained with the free one. This means that the immobilization procedure did not alter the catalytic properties of the tyrosinase. In addition, the surface modification of the PVDF made it a promising material to use in enzyme or biomolecule immobilization processes.