Inactivating SARS-CoV-2 Using 275 nm UV-C LEDs through a Spherical Irradiation Box: Design, Characterization and Validation.

We report on the design, characterization and validation of a spherical irradiation system for inactivating SARS-CoV-2, based on UV-C 275 nm LEDs. The system is designed to maximize irradiation intensity and uniformity and can be used for irradiating a volume of 18 L. To this aim: (i) several commercially available LEDs have been acquired and analyzed; (ii) a complete optical study has been carried out in order to optimize the efficacy of the system; (iii) the resulting prototype has been characterized optically and tested for the inactivation of SARS-CoV-2 for different exposure times, doses and surface types; (iv) the result achieved and the efficacy of the prototype have been compared with similar devices based on different technologies. Results indicate that a 99.9% inactivation can be reached after 1 min of treatment with a dose of 83.1 J/m2.

Cell-seeded 3D scaffolds as in vitro models for electroporation.

Electroporation of cells is usually studied using cell suspensions or monolayer cultures. 3D scaffolds for cell culture have been recently designed in order to reproduce in vitro the complex and multifactorial environment experimented in vivo by cells. In fact, it is well known that 2D cell cultures are not able to simulate the complex interactions between the cells and their extracellular matrix (ECM). Recently, some examples of 3D models, like spheroids, have been investigated also in the electroporation field. Spheroids have been proposed in electrochemotherapy (ECT) studies to mimic tumor in vivo conditions: they are easy-to-handle 3D models but their sensitivity to electric field pulses depends from their diameter and, more interestingly, despite being relevant for intercellular junctions, they are not so much so for cell-ECM interactions. In this work, we propose a 3D macroscopic myxoid matrix for cell culture that would mimic the in vivo environment of myxoid stroma tumors. The myxoid stroma consists of abundant basic substances with large amounts of glycosaminoglycans (hyaluronic acid) and proteoglycans, poor collagen fibers and no elastin content. In the proposed approach, tumor cells seeded on 3D scaffolds mimic of myxoid stroma can establish both cell-cell and cell-ECM 3D interactions. The MCF7 cells (human breast adenocarcinoma cell line) were seeded in complete culture medium. Cell cultures were incubated at 37 °C for either 24 h, 3 days or 7 day. Some samples were used to assess cell vitality using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) test and others for electroporation tests and for histopathological analysis. The electroporation has been verified by the fluorescent dye Propidium cellular uptake. The proposed myxoid stroma scaffold induces cell proliferation and shows fibrous structures produced by cells, the concentration of which increases with culture time. The proposed matrix will be used for further investigations as a new scaffold for cell culture. Tumor cells grown into these new scaffolds will be used to evaluate electroporation including the stroma effect.

Effect of Tissue Inhomogeneity in Soft Tissue Sarcomas: From Real Cases to Numerical and Experimental Models.

Electrochemotherapy is an established treatment option for patients with superficially metastatic tumors, mainly malignant melanoma and breast cancer. Based on preliminary experiences, electrochemotherapy has the potential to be translated in the treatment of larger and deeper neoplasms, such as soft tissue sarcomas. However, soft tissue sarcomas are characterized by tissue inhomogeneity and, consequently, by variable electrical characteristic of tumor tissue. The inhomogeneity in conductivity represents the cause of local variations in the electric field intensity. Crucially, this fact may hamper the achievement of the electroporation threshold during the electrochemotherapy procedure. In order to evaluate the effect of tissue inhomogeneity on the electric field distribution, we first performed ex vivo analysis of some clinical cases to quantify the inhomogeneity area. Subsequently, we performed some simulations where the electric field intensity was evaluated by means of finite element analysis. The results of the simulation models are finally compared to an experimental model based on potato and tissue mimic materials. Tissue mimic materials are materials where the conductivity can be suitably designed. The coupling of computation and experimental results could be helpful to show the effect of the inhomogeneity in terms of variation in electric field distribution and characteristics.

Effect of Electrode Distance in Grid Electrode: Numerical Models and In Vitro Tests.

Electrochemotherapy is an emerging local treatment for the management of superficial tumors and, among these, also chest wall recurrences from breast cancer. Generally, the treatment of this peculiar type of tumor requires the coverage of large skin areas. In these cases, electrochemotherapy treatment by means of standard small size needle electrodes (an array of 0.73 cm spaced needles, which covers an area of 1.5 cm2) is time-consuming and can allow an inhomogeneous coverage of the target area. We have previously designed grid devices suitable for treating an area ranging from 12 to 200 cm2. In this study, we propose different approaches to study advantages and drawbacks of a grid device with needles positioned 2 cm apart. The described approach includes a numerical evaluation to estimate electric field intensity, followed by an experimental quantification of electroporation on a cell culture. The electric field generated in a conductive medium has been studied by means of 3-dimensional numerical models with varying needle pair distance from 1 to 2 cm. In particular, the electric field evaluation shows that the electric field intensity with varying needle distance is comparable in the area in the middle of the 2 electrodes. Differently, near needles, the electric field intensity increases with the increasing electrode distance and supply voltage. The computational results have been correlated with experimental ones obtained in vitro on cell culture. In particular, electroporation effect has been assessed on human breast cancer cell line MCF7, cultured in monolayer. The use of 2-cm distant needles, supplied by 2000 V, produced an electroporation effect in the whole area comprised between the electrodes. Areas of cell culture where reversible and irreversible electroporation occurred were identified under microscope by using fluorescent dyes. The coupling of computation and experimental results could be helpful to evaluate the effect of the needle distance on the electric field intensity in cell cultures in terms of reversible or irreversible electroporation.

Synthesis of Ferrofluids Made of Iron Oxide Nanoflowers: Interplay between Carrier Fluid and Magnetic Properties.

Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and magnetic characteristics, including interparticle magnetic interactions. Magnetic nanoparticles were prepared by thermal decomposition of iron(III) chloride hexahydrate (FeCl3·6H2O) in 2-pyrrolidone, and were then dispersed in two different fluids, water and polyethylene glycol 400 (PEG). A number of experimental techniques (especially, transmission electron microscopy, Mössbauer spectroscopy and superconducting quantum interference device (SQUID) magnetometry) were employed to study both the as-prepared nanoparticles and the ferrofluids. We show that, with the adopted synthesis parameters of temperature and FeCl3 relative concentration, nanoparticles are obtained that mainly consist of maghemite and present a high degree of structural disorder and strong spin canting, resulting in a low saturation magnetization (~45 emu/g). A remarkable feature is that the nanoparticles, ultimately due to the presence of 2-pyrrolidone at their surface, are arranged in nanoflower-shape structures, which are substantially stable in water and tend to disaggregate in PEG. The different arrangement of the nanoparticles in the two fluids implies a different strength of dipolar magnetic interactions, as revealed by the analysis of their magnetothermal behavior. The comparison between the magnetic heating capacities of the two ferrofluids demonstrates the possibility of tailoring the performances of the produced nanoparticles by exploiting the interplay with the carrier fluid.

Magnetic hyperthermia efficiency and (1)H-NMR relaxation properties of iron oxide/paclitaxel-loaded PLGA nanoparticles.

Magnetic iron oxide nanoparticles (Fe-NPs) can be exploited in biomedicine as agents for magnetic fluid hyperthermia (MFH) treatments and as contrast enhancers in magnetic resonance imaging. New, oleate-covered, iron oxide particles have been prepared either by co-precipitation or thermal decomposition methods and incorporated into poly(lactic-co-glycolic acid) nanoparticles (PLGA-Fe-NPs) to improve their biocompatibility and in vivo stability. Moreover, the PLGA-Fe-NPs have been loaded with paclitaxel to pursue an MFH-triggered drug release. Remarkably, it has been found that the nanoparticle formulations are characterized by peculiar (1)H nuclear magnetic relaxation dispersion (NMRD) profiles that directly correlate with their heating potential when exposed to an alternating magnetic field. By prolonging the magnetic field exposure to 30 min, a significant drug release was observed for PLGA-Fe-NPs in the case of the larger-sized magnetic nanoparticles. Furthermore, the immobilization of lipophilic Fe-NPs in PLGA-NPs also made it possible to maintain Néel relaxation as the dominant relaxation contribution in the presence of large iron oxide cores (diameters of 15-20 nm), with the advantage of preserving their efficiency when they are entrapped in the intracellular environment. The results reported herein show that NMRD profiles are a useful tool for anticipating the heating capabilities of Fe-NPs designed for MFH applications.

A prototype of a flexible grid electrode to treat widespread superficial tumors by means of Electrochemotherapy.

BACKGROUND: In recent years, superficial chest wall recurrence from breast cancer can be effectively treated by means of electrochemotherapy, with the majority of patients achieving response to treatment. Nevertheless, tumor spread along superficial lymphatic vessels makes this peculiar type of tumor recurrence prone to involve large skin areas and difficult to treat. In these cases, electroporation with standard, small size needle electrodes can be time-consuming and produce an inhomogeneous coverage of the target area, ultimately resulting in patient under treatment. MATERIALS AND METHODS: Authors designed and developed a prototype of a flexible grid electrode aimed at the treatment of large skin surfaces and manufactured a connection box to link the pulse applicator to a voltage pulse generator. Laboratory tests on potato tissue were performed in order to evaluate the electroporation effect, which was evaluated by observing color change of treated tissue. RESULTS: A device has been designed in order to treat chest wall recurrences from breast cancer. According to preliminary tests, the new flexible support of the electrode allows the adaptability to the surface to be treated. Moreover, the designed devices can be useful to treat a larger surface in 2-5 minutes. CONCLUSIONS: Authors developed the prototype of a new pulse applicator aimed at the treatment of widespread superficial tumors. This flexible grid needle electrode was successfully tested on potato tissue and produced an electroporation effect. From a clinical point of view, the development of this device may shorten electrochemotherapy procedure thus allowing clinicians to administer electric pulses at the time of maximum tumor exposure to drugs. Moreover, since the treatment time is 2-5 min long, it could also reduce the time of anesthesia, thus improving patient recovery.

Numerical model for RF capacitive regional deep hyperthermia in pelvic tumors.

A numerical model based on Finite Element Method (FEM) for the prediction of power density distribution and temperature during RF-capacitive hyperthermia treatment has been presented in the paper and the results are discussed. In particular the models are related to the treatment of pelvic tumors where it is more difficult to localize and focus heat in deep regions. The geometrical and physical model of the patient is reconstructed with a segmentation procedure by means of dedicated software. The geometrical meshed model has been used as input for the solution of coupled electromagnetic and thermal problems. A deep analysis of different configurations derived from specific scientific literature of the last years has been presented in the paper and discussed. The results obtained by FEM analyses have demonstrated the suitability of this method for the prediction of power and temperature distribution during RF capacitive hyperthermia and that the calculation procedure is an efficient mean to evaluate the efficacy of the heating system.