Ricerc@Sapienza

Patients affected by aggressive neoplasms with a high propensity to metastasize to the skin, such as some head and neck cancers, can benefit from electrochemotherapy, a modality that combines electroporation of cell membranes and chemotherapy to facilitate the transport of non-permeant molecules into cells; the host immune response consequently participates in achieving cure of tumors.

Microsecond pulsed electric fields (?sPEFs) with amplitude of tens of kV/m are used to permeabilize the plasma membrane whereas nanosecond pulsed electric fields of MV/m also permeabilize cell internal structures, such as the endoplasmic reticulum. In this work, a numerical realistic model of cell and its reticulum has been realized to study the use of ?sPEFs also for the permeabilization of this internal structure

Nano-systems, often used in biomedical applications for the treatment of a broad category of illnesses, represent one of the nanomedicine approaches recently proposed to target specific drugs only in the region where the disease has been developed. Recently the use of this technique has been proposed with electropulsation, hence taking advantage of the enhanced permeabilization of the cell membrane and simultaneously control the release of the encapsulated drug by the nano-system.

Smart drug delivery systems represent an interesting tool to significantly improve the efficiency and the precision in the treatment of a broad category of diseases. In this context, a drug delivery mediated by nanosecond pulsed electric fields seems a promising technique, allowing for a controlled release and uptake of drugs by the synergy between the electropulsation and nanocarriers with encapsulated drugs.

Recently, the use of nanometer liposomes as nanocarriers in drug delivery systems mediated by nanoelectroporation has been proposed. This technique takes advantage of the possibility of simultaneously electroporating liposomes and cell membrane with 10-nanosecond pulsed electric fields (nsPEF) facilitating the release of the drug from the liposomes and at the same time its uptake by the cells. In this paper the design and characterization of a 10 nsPEF exposure system is presented, for liposomes electroporation purposes.

We present here a new method for calculating the radius of a transmembrane pore in a phospholipid bilayer. To compare size-related properties of pores in bilayers of various compositions, generated and maintained under different physical and chemical conditions, reference metrics are needed. Operational metrics can be associated with some observed behavior. For example, pore size can be defined by the largest object that will pass through the length of the pore.

Electroporation characterization is a topic of intensive interest probed by extensive ongoing research efforts. Usually, these studies are carried out on lipid-bilayer electroporation. Surprisingly, the possibility of water-channel electropore formation across transmembrane proteins themselves, particularly in view of such a promising application, has not yet been elucidated.

The initiation of action potentials (APs) by membrane depolarization occurs after a brief vulnerability period, during which excitation can be abolished by the reversal of the stimulus polarity. This vulnerability period is determined by the time needed for gating of voltage-gated sodium channels (VGSC). We compared nerve excitation by ultra-short uni- and bipolar stimuli to define the time frame of bipolar cancellation and of AP initiation.

To deep more insight into basic phenomena occurring during and after electropulsation of biological membranes, a new experimental modality has been used. It combines a wide field Coherent Anti Stokes Raman Spectroscopy system with a coplanar wave guide able to deliver nanosecond pulsed electric fields to different in vitro samples. The experiments have been conducted on liposome suspensions. These systems well mimic phospholipid double layers. Spectra of liposome suspensions have been acquired immediately after electropulsation.

The increasing interest toward biocompatible nanotechnologies in medicine, combined with electric fields stimulation, is leading to the development of electro-sensitive smart systems for drug delivery applications. To this regard, recently the use of pulsed electric fields to trigger release across phospholipid membranes of liposomes has been numerically studied, for a deeper understanding of the phenomena at the molecular scale.