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Organoids are emerging as a powerful tool to investigate complex biological structures in vitro. Vascularization of organoids is crucial to recapitulate the morphology and function of the represented human organ, especially in the case of the kidney, whose primary function of blood filtration is closely associated with blood circulation. Current in vitro microfluidic approaches have only provided initial vascularization of kidney organoids, whereas in vivo transplantation to animal models is problematic due to ethical problems, with the exception of xenotransplantation onto a chicken chorioallantoic membrane (CAM). Although CAM can serve as a good environment for vascularization, it can only be used for a fixed length of time, limited by development of the embryo. Here, we propose a novel lab on a chip design that allows organoids of different origin to be cultured and vascularized on a CAM, as well as to be transferred to in vitro conditions when required. Mouse embryonic kidneys cultured on the CAM showed enhanced vascularization by intrinsic endothelial cells, and made connections with the chicken vasculature, as evidenced by blood flowing through them. After the chips were transferred to in vitro conditions, the vasculature inside the organoids was successfully maintained. To our knowledge, this is the first demonstration of the combination of in vivo and in vitro approaches applied to microfluidic chip design. [ABSTRACT FROM AUTHOR]

Particle cross-stream migration in electrohydrodynamic microfluidic systems exhibits intriguing behaviors, which makes it interesting when viewed from a fundamental perspective and promising for nanoparticle focusing and separation applications. So far, particle behavior in such systems has been explained with the slip-induced lift force model (Saffman model), which predicts particle central or side focusing based on the direction of electric field and fluid flow. However, in our previous work, we observed particle migration patterns that did not adhere to the prediction of the Saffman model. In this work, we further studied this novel particle lateral migration behavior, which we termed the "anti-Saffman" behavior. We experimentally investigated how changing the conductivity of the suspending medium influences particle behavior and quantitatively measured the net lateral force experienced by the particles. Then, we compared this net force with the prediction of the relevant lift force models in the literature. We concluded that the anti-Saffman behavior is positively correlated with medium conductivity and shear rate (∝ γ ̇ 2 ). Furthermore, the comparison with the existing force models revealed that none of them can predict the experimentally observed particle lift. The net lift predicted by hydrodynamic lift models indicated that the underlying mechanism behind our experiments also potentially has a hydrodynamic origin. We believe this phenomenon offers the possibility of manipulating and separating nanoparticles suspended in standard aqueous electrolyte solutions, which makes it applicable to various biological samples. [ABSTRACT FROM AUTHOR]

Phenylketonuria (PKU) is characterized by an autosomal recessive mutation in the phenylalanine hydroxylase (PAH) gene. Impaired PAH enzyme activity leads to the accumulation of phenylalanine (Phe) and its metabolites in the bloodstream, which disrupts the central nervous system and causes psychomotor retardation. Early diagnosis of PKU is essential for timely intervention. Moreover, continuous monitoring of blood Phe levels is indispensable for prognosis, requiring a robust and reliable monitoring system. This study presents an automated lab-on-a-CD-based system for early diagnosis and monitoring of PKU treatment. This miniaturised system contains CD-shaped disposable cartridges, a mini centrifuge, and an electrochemical sensing unit. Modified screen-printed gold electrodes were used for the electrochemical measurements in cartridges. Electrode modification was conducted by electrochemical graphene oxide reduction and deposition on the electrode surface, which increased the sensitivity of the measurement 1.5 fold. The system used amperometric detection to measure Phe in the blood through oxidation of NAD + to NADH by the enzyme phenylalanine dehydrogenase. The limit of detection (LOD), limit of quantification (LOQ), and sensitivity of the system were 0.0524, 0.1587 mg dL -1 and 0.3338 μA mg -1 dL, respectively, within the 0-20 mg dL -1 measurement range ( R 2 = 0.9955). The performance of the lab-on-a-CD system was compared to the gold standard HPLC method. The accuracy was 83.1% for HPLC and 84.1% for the lab-on-a-CD system. In conclusion, this study successfully developed a portable diagnostic device for rapid (under 20 min), accurate and highly sensitive detection of Phe in whole blood.