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Organ‐on‐chip (OOC) platforms have attracted attentions of pharmaceutical companies as powerful tools for screening of existing drugs and development of new drug candidates. OOCs have primarily used human cell lines or primary cells to develop biomimetic tissue models. However, the ability of human stem cells in unlimited self‐renewal and differentiation into multiple lineages has made them attractive for OOCs. The microfluidic technology has enabled precise control of stem cell differentiation using soluble factors, biophysical cues, and electromagnetic signals. This study discusses different tissue‐ and organ‐on‐chip platforms (i.e., skin, brain, blood–brain barrier, bone marrow, heart, liver, lung, tumor, and vascular), with an emphasis on the critical role of stem cells in the synthesis of complex tissues. This study further recaps the design, fabrication, high‐throughput performance, and improved functionality of stem‐cell‐based OOCs, technical challenges, obstacles against implementing their potential applications, and future perspectives related to different experimental platforms.

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Branching and crosslinking of polyhydroxybutyrate (PHB) is accomplished for the first time through reactive modification in the melt state, using dicumyl peroxide (DCP) as the free-radical initiator and a tri-functional coagent, triallyl trimesate (TAM). The dynamic oscillatory rheological properties, as well as extensional viscosities provide strong evidence of branching and crosslinking, depending on the amounts of DCP and TAM. In addition to the significant increases in viscosity due to branching/crosslinking, coagent modified samples exhibit a significant increase in the crystallization temperature, indicative of a nucleating effect, accompanied by a decrease of crystal spherulite sizes. In addition, the solid-state storage modulus in DMTA experiments is 65% higher in formulations that contain high gel contents, whereas the glass transition temperature of the cured formulations is slightly lower. Coagent modified PHB exhibit a substantial improvement in the thermal stability, both in isothermal dynamic oscillatory temperature sweeps, as well as non-isothermal TGA experiments.

Development of predictive multi-organ models before implementing costly clinical trials is central for screening the toxicity, efficacy, and side effects of new therapeutic agents. Despite significant efforts that have been recently made to develop biomimetic in vitro tissue models, the clinical application of such platforms is still far from reality. Recent advances in physiologically-based pharmacokinetic and pharmacodynamic (PBPK-PD) modeling, micro- and nanotechnology, and in silico modeling have enabled single- and multi-organ platforms for investigation of new chemical agents and tissue-tissue interactions. This review provides an overview of the principles of designing microfluidic-based organ-on-chip models for drug testing and highlights current state-of-the-art in developing predictive multi-organ models for studying the cross-talk of interconnected organs. We further discuss the challenges associated with establishing a predictive body-on-chip (BOC) model such as the scaling, cell types, the common medium, and principles of the study design for characterizing the interaction of drugs with multiple targets.

In this work, the surface morphology and properties of ternary polymer blends and the migration of minor component molecules to the top surface layer of the films were studied. We used polystyrene (PS), poly(butylene adipate-co-terephthalate), polycaprolactone, poly(methyl methacrylate), and polylactide as second minor phases in a blend of polyethylene terephthalate-poly(ethylene glycol) (PET-PEG). The morphology of the ternary systems predicted using the spreading coefficient and relative interfacial energy concepts was confirmed by scanning electron microscopy images. The surface characterization results showed a higher rate of migration of PEG to the polymer-air interface in the systems with a nonwetting morphology and the highest in the PET-PS-PEG blend. Atomic force microscopy images suggested that the high surface hydrophilicity of the PET-PS-PEG blend is due to a dendritic pattern of PEG crystals on the film surface, which were not observed for the other samples.

Abstract. Controlling the adhesion of the polymer surface is a key issue in surface science, since polymers have been a commonly used material for many years. The surface modification in this study includes two different aspects. One is to enhance the hydrophilicity and the other is to create the roughness on the PET film surface. In this study we developed a novel and simple approach to modify polyethylene terephthalate (PET) film surface through polymer blending in twinscrew extruder. One example described in the study uses polyethylene glycol (PEG) in polyethylene terephthalate (PET) host to modify a PET film surface. Low content of polystyrene (PS) as a third component was used in the system to increase the rate of migration of PEG to the surface of the film. Surface enrichment of PEG was observed at the polymer/air interface of the polymer film containing PET-PEG-PS whereas for the PET-PEG binary blend more PEG was distributed within the bulk of the sample. Furthermore, a novel method to create roughness at the PET film surface was proposed. In order to roughen the surface of PET film, a small amount of PKHH phenoxy resin to change PS/PET interfacial tension was used. The compatibility effect of PKHH causes the formation of smaller PS droplets, which were able to migrate more easily through PET matrix. Consequently, resulting in a locally elevated concentration of PS near the surface of the film. The local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in theinstabilities on the surface of the film.

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