Bacteriophage uptake by mammalian cell layers represents a potential sink that may impact phage therapy.

It is increasingly apparent that bacteriophages, viruses that infect bacteria and more commonly referred to as simply phages, have tropisms outside their bacterial hosts. Using live tissue culture cell imaging, we demonstrate that cell type, phage size, and morphology play a major role in phage internalization. Uptake was validated under physiological conditions using a microfluidic device. Phages adhered to mammalian tissues, with adherent phages being subsequently internalized by macropinocytosis, with functional phages accumulating intracellularly. We incorporated these results into a pharmacokinetic model demonstrating the potential impact of phage accumulation by cell layers, which represents a potential sink for circulating phages in the body. During phage therapy, high doses of phages are directly administered to a patient in order to treat a bacterial infection, thereby facilitating broad interactions between phages and mammalian cells. Understanding these interactions will have important implications on innate immune responses, phage pharmacokinetics, and the efficacy of phage therapy.

Risk assessment on-a-chip: a cell-based microfluidic device for immunotoxicity screening.

Nanomaterials are widely used in industrial and clinical settings due to their unique physical and chemical properties. However, public health and environmental concerns have emerged owing to their undesired toxicity and ability to trigger immune responses. This paper presents the development of a microfluidic-based cell biochip device that enables the administration of nanoparticles under laminar flow to cells of the immune system to assess their cytotoxicity. The exposure of human B lymphocytes to 10 nm silver nanoparticles under fluid flow led to a 3-fold increase in toxicity compared to static conditions, possibly indicating enhanced cell-nanoparticle interactions. To investigate whether the administration under flow was the main contributing factor, we compared and validated the cytotoxicity of the same nanoparticles in different platforms, including the conventional well plate format and in-house fabricated microfluidic devices under both static and dynamic flow conditions. Our results suggest that commonly employed static platforms might not be well-suited to perform toxicological screening of nanomaterials and may lead to an underestimation of cytotoxic responses. The simplicity of the developed flow system makes this setup a valuable tool to preliminary screen nanomaterials.

In Situ Surface Modification of Microfluidic Blood-Brain-Barriers for Improved Screening of Small Molecules and Nanoparticles.

Here, we have developed and evaluated a microfluidic-based human blood-brain-barrier (µBBB) platform that models and predicts brain tissue uptake of small molecule drugs and nanoparticles (NPs) targeting the central nervous system. By using a photocrosslinkable copolymer that was prepared from monomers containing benzophenone and N-hydroxysuccinimide ester functional groups, we were able to evenly coat and functionalize µBBB chip channels in situ, providing a covalently attached homogenous layer of extracellular matrix proteins. This novel approach allowed the coculture of human endothelial cells, pericytes, and astrocytes and resulted in the formation of a mimic of cerebral endothelium expressing tight junction markers and efflux proteins, resembling the native BBB. The permeability coefficients of a number of compounds, including caffeine, nitrofurantoin, dextran, sucrose, glucose, and alanine, were measured on our µBBB platform and were found to agree with reported values. In addition, we successfully visualized the receptor-mediated uptake and transcytosis of transferrin-functionalized NPs. The BBB-penetrating NPs were able to target glioma cells cultured in 3D in the brain compartment of our µBBB. In conclusion, our µBBB was able to accurately predict the BBB permeability of both small molecule pharmaceuticals and nanovectors and allowed time-resolved visualization of transcytosis. Our versatile chip design accommodates different brain disease models and is expected to be exploited in further BBB studies, aiming at replacing animal experiments.

Advances in Microfluidic Blood-Brain Barrier (BBB) Models.

Therapeutic options for neurological disorders currently remain limited. The intrinsic complexity of the brain architecture prevents potential therapeutics from reaching their cerebral target, thus limiting their efficacy. Recent advances in microfluidic technology and organ-on-chip systems have enabled the development of a new generation of in vitro platforms that can recapitulate complex in vivo microenvironments and physiological responses. In this context, microfluidic-based in vitro models of the blood-brain barrier (BBB) are of particular interest as they provide an innovative approach for conducting research related to the brain, including modeling of neurodegenerative diseases and high-throughput drug screening. Here, we present the most recent advances in BBB-on-chip devices and examine validation steps that will strengthen their future applications.

Characterisation of nanomaterial hydrophobicity using engineered surfaces.

Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors. Graphical abstractDetermination of hydrophobicity character of nanomaterials by measuring their affinity to engineered surfaces.