Liposome production by microfluidics: potential and limiting factors

This paper provides an analysis of microfluidic techniques for the production of nanoscale lipid-based vesicular systems. In particular we focus on the key issues associated with the microfluidic production of liposomes. These include, but are not limited to, the role of lipid formulation, lipid concentration, residual amount of solvent, production method (including microchannel architecture), and drug loading in determining liposome characteristics. Furthermore, we propose microfluidic architectures for the mass production of liposomes with a view to potential industrial translation of this technology

Occurrence of mislabelling in prepared fishery products in Southern Italy

Fish authentication is a major concern not only for the prevention of commercial fraud, but also for the assessment of safety risks deriving from the undeclared introduction of potentially dangerous toxic or allergenic substances or environmentally damaging fish where endangered species are involved. Moreover, food authentication might affect the diet of certain groups of consumers, such as followers of religious practices. Considering the authentication of fish products is one of the key issues in food safety, quality and sustainability, the aim of this work was to investigate the prevalence of mislabelling in sole (Solea solea), plaice (Pleuronectes platessa), Atlantic salmon (Salmo salar), and hake (Merluccius merluccius) fillets from markets and supermarkets located in Apulia (Southern Italy) using DNA barcoding. The results of the molecular investigations reveal that 42/98 (42.8%) fillet samples were not correctly labelled. In particular, 12/27 (44.4%) fillets of sole (Solea solea) were identified as belonging to Solea senegalensis. In addition, 13/28 (46.4%) plaice (Pleuronectes platessa) samples were identified as Pangasius hypophtalmus. All Atlantic salmon (Salmo salar) samples were correctly labelled. Post-sequencing data analysis revealed that 17/30 (56.6%) hake fillets (Merluccius merluccius) were not correctly labelled, of which 8/30 samples identified as Merluccius hubbsi, 5/30 samples as Merluccius products and 4/30 as Merluccius capensis. The study reveals a high occurrence of species mislabelling in the prepared fish fillet products, further evidence of the need for increased traceability and assessment of the authenticity of food products

A film-forming graphene/diketopyrrolopyrrole covalent hybrid with far-red optical features: Evidence of photo-stability

A dianiline derivative of a symmetric donor-acceptor-donor diketopyrrolopyrrole-based dye is employed for the two-sided covalent functionalization of liquid exfoliated few layers graphene flakes, through a direct arylation reaction. The resulting nanohybrid features the properties of a polymeric species, being solution-processed into homogeneous thin films, featuring a pronounced red-shift of the main absorption band with respect to the model dye unit and energy levels comparable to those of common diketopyrrolopyrrole-based polymers. A good electrical conductivity and the absence of radical signals generated after intense white light illumination, as probed through electron paramagnetic resonance, suggest a possible future application of this composite material in the field of photoprotective, antistatic layers with tunable colors

Epidemiological study of pathogens collected from blood for a period of a year (2008-2009)

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Understanding the biological and physical effects of sclerotherapy

Sclerotherapy is currently employed to effectively treat varicose veins, and relies on the injection of liquid or foamed agents causing endothelial wall damage, vessel shrinkage, and subsequent neovascularization. Pre-clinical in vitro studies are conducted to characterize the performance of sclerosing agents; however, they often do not replicate physiologically relevant physical and biological conditions. In this study, three models have been developed in order to gain a more comprehensive understanding of the physical and biological effects of sclerosing agents. These include: (i) 2D in vitro models, (ii) ex vivo models, and (iii) 3D vein-on-a-chip (VOC).The 2D in vitro model has been employed to quantify the efficacy of sclerosing agents onto a monolayer of endothelial cells. The model allowed investigating the effect of clinically-relevant parameters, including different administration conditions. Moreover, the first systematic comparison of the biological performance of different polidocanol-based sclerosing foam formulations (PEM and physician compounded foams) was carried out, including an attempt to correlate biological effects with foam physical properties. It has been demonstrated that PEM was the most effective foam at disrupting the endothelial layer in a variety of tests and over different timescales of treatment. This was attributed to the slower drainage dynamics of PEM compared to physician compounded foams, and – potentially – to the enhanced polidocanol mobility conferred by its gas formulation.Subsequently, a quantitative microscopy technique was employed to quantify the level of disruption of cell membranes subject to sclerotherapy. With this method, it was found that exposure to sclerosants causes changes to the lipid packing of cell membranes. Therefore, measurement of the variations in membrane lipid packing was employed to evaluate the biophysical effects of sclerosing agents. Findings were generally in agreement with the results obtained from in vitro efficacy tests. The ability of POL to penetrate and perturb the membrane lipid bilayer was found to be concentration dependent. Similar results were obtained comparing foamed and liquid POL.Whilst 2D models enabled the investigation of the effect of sclerosants at the cellular level, they did not reproduce the 3D architecture and fluid dynamic environment typical of a varicose vein. Therefore, they were not suitable for investigating the interaction of sclerosing agents with blood in a biomimetic environment. For this reason, ex vivo models have been developed using umbilical cord veins, in order to quantifying sclerosant-induced disruption of the vessel wall using a colorimetric assay. Experiments were carried out using both liquid and foamed sclerosants, in either static or dynamic conditions, and in the presence of blood. When blood was perfused through the umbilical vein, all treatment methods presented similar efficacy.Afterwards, 3D Vein-on-a-chip (VOCs) models lined with human endothelial cells were developed. Models replicated the architecture of physiological and varicose veins. VOCs were produced in polydimethylsiloxane (PDMS) applying 3D-printing and soft-lithography techniques, and were employed for evaluating the mechanical properties of foams. A protocol was designed to replicate the clinical administration process, using physiologically relevant vein diameter, geometry, and inclination angle (i.e. replicating leg elevation), and reproducing bulk physical properties of blood. The vein-on-a-chip models and experimental methods developed in this study provide a novel technology platform to measure the behaviour of different formulations of sclerosing foams, at physical conditions that resemble their clinical administration.Despite PDMS-based VOCs provide a useful model to investigate the flow behavior of sclerosing foams and its relation to biological performance, they do not fully replicate the physical properties of both vascular and extra-vascular compartments of a vein. In order to overcome this limitation, the development of hydrogel-based models has been investigated. A method has been developed to manufacture channel geometries inside a hydrogel-based scaffold.Overall, these technological developments and research findings can form the basis for a novel technological pipeline to accelerate clinical translation and innovation of sclerosing agents

Analysis of the Diffusion Process by pH Indicator in Microfluidic Chips for Liposome Production

In recent years, the development of nano- and micro-particles has attracted considerable interest from researchers and enterprises, because of the potential utility of such particles as drug delivery vehicles. Amongst the different techniques employed for the production of nanoparticles, microfluidic-based methods have proven to be the most effective for controlling particle size and dispersity, and for achieving high encapsulation efficiency of bioactive compounds. In this study, we specifically focus on the production of liposomes, spherical vesicles formed by a lipid bilayer encapsulating an aqueous core. The formation of liposomes in microfluidic devices is often governed by diffusive mass transfer of chemical species at the liquid interface between a solvent (i.e., alcohol) and a non-solvent (i.e., water). In this work, we developed a new approach for the analysis of mixing processes within microfluidic devices. The method relies on the use of a pH indicator, and we demonstrate its utility by characterizing the transfer of ethanol and water within two different microfluidic architectures. Our approach represents an effective route to experimentally characterize diffusion and advection processes governing the formation of vesicular/micellar systems in microfluidics, and can also be employed to validate the results of numerical modelling

Analysis of the diffusion process by pH indicator in microfluidic chips for liposome production

In recent years, the development of nano- and microparticles has drawn significant interest from researchers and enterprises because of the potential utility of such particles as drug delivery vehicles. Amongst the different techniques employed for the production of nanoparticles, microfluidic-based methods have proven to be the most effective for controlling particle size and dispersity, and for achieving high encapsulation efficiency of bioactive compounds. In this study we specifically focus on the production of liposomes, spherical vesicles formed by a lipid bilayer encapsulating an aqueous core. The formation of liposomes in microfluidic devices is often governed by diffusive mass transfer of chemical species at the liquid interface between a solvent (i.e. alcohol) and a non-solvent (i.e. water). In this work, we developed a new approach for the analysis of mass transport phenomena within microfluidic devices. The method relies on the use of a pH indicator, and we demonstrate its utility by characterising the transfer of ethanol and water within two different microfluidic architectures. Our approach represents an effective route to experimentally characterise diffusion and advection processes governing the formation of vesicular/micellar systems in microfluidics, and can also be employed to validate the results of numerical modelling

Liposomal Systems as Nanocarriers for the Antiviral Agent Ivermectin

RNA virus infections can lead to the onset of severe diseases such as fever with haemorrhage, multiorgan failure, and mortality. The emergence and reemergence of RNA viruses continue to pose a significant public health threat worldwide with particular attention to the increasing incidence of flaviviruses, among others Dengue, West Nile Virus, and Yellow Fever viruses. Development of new and potent antivirals is thus urgently needed. Ivermectin, an already known antihelminthic drug, has shown potent effects in vitro on Flavivirus helicase, with EC50 values in the subnanomolar range for Yellow Fever and submicromolar EC50 for Dengue Fever, Japanese encephalitis, and tick-borne encephalitis viruses. However ivermectin is hampered in its application by pharmacokinetic problems (little solubility and high cytotoxicity). To overcome such problems we engineered different compositions of liposomes as ivermectin carriers characterizing and testing them on several cell lines for cytotoxicity. The engineered liposomes were less cytotoxic than ivermectin alone and they showed a significant increase of the antiviral activity in all the Dengue stains tested (1, 2, and S221). In the current study ivermectin is confirmed to be an effective potential antiviral and liposomes, as drug carriers, are shown to modulate the drug activity. All together the results represent a promising starting point for future improvement of ivermectin as antiviral and its delivery