Despite the last 60 years have seen major advances in many scientific and technological inputs of drug Research and Development, the number of new molecules hitting the market per billion US dollars of R&D spending has been declined steadily during the same period. The current scenario highlights the need for new research tools to enable reduce costly animal and clinical trials while providing a better prediction about drug efficacy and security in humans A recent emerging approach to improve the current models is emerging from the field of microfluidics, which studies systems that process or manipulate tiny amounts of fluids using channels with dimensions of tens to hundreds of micrometers. Combining microfluidics with cell culture, scientists gave rise to a new field named “Organ-on-chip” (OOC). Microfluidic OOCs are advanced platforms designed to mimic physiological structures and continuous flow conditions, thus allowing the culture of cells in a friendlier microenvironment. This thesis, titled “Cell culture interfaces for different organ-on-chip applications: from photolithography to rapid-prototyping techniques with sensor embedding”, aims to design, simulate and test new OOC devices to reproduce cell culture interface under flow conditions. The work has a focus on the exploration of novel fabrication techniques which enable rapid prototyping of OOC devices, reducing costs, time and human labor associated to the fabrication process. The final objective is to demonstrate the viability of the devices as research tools for biological problems, applying them to the tubular kidney and the blood brain barrier (BBB). To achieve the objective, at least three device version have been developed: 1) OOCv1, fabricated by multilayer PDMS soft lithography; 2) OOCv2, fabricated in thermoplastic by layered object manufacturing using both a vinyl cutter and a laser cutter, integrating standard fluidic connectors alone (OOCv2.1) or together with embedded electrodes (OOCv2.2); 3) OOCv3 using a mixed technique of laser cut and 3D printing by stereolithography. All devices are fabricated using biocompatible materials with high optical quality and an embedded commercial membrane. The biological experiments with renal tubular epithelial cells, realized on OOCv1 and OOCv2.1 devices, demonstrated the viability of the device for culturing cells under flow conditions. The study realized on fatty acid oxidation and accumulation in cells exposed to physiological and diabetogenic oscillating levels of glucose suggest a possible positive role of shear stress in activation of fatty acid metabolism. The studies were performed using a compact experimental unit with embedded flow control which reduce significatively the complexity and cost of the fluidic experimental setup. The biological experiments on the BBB confirmed viability of OOCv2.1 and OOCv2.2 for compartmentalized co-culturing of endothelial cells and pericytes. The formation and recovery of the barrier after disruptive treatment has been assessed using different techniques, including immunostaining, fluorescence and live phase contrast imaging, and electrical impedance spectroscopy. The repeatability of measurements using electrodes was verified. A model to classify measurements from different timepoints has been developed, resulting in accuracy of 100% in learning and 90% in testing case. Results are confirmed by imaging data, which also suggest a critical role of pericytes in the development, maintenance, and regulation of BBB, in accordance with the literature.
Usó, Vanessa Ghiraldeli, Sandnes, Frode Eika, and Medola, Fausto Orsi
Usó, V.G., Sandnes, F.E. & Medola, F.O. (2020). Using virtual reality and rapid prototyping to co-create together with hospitalized children. In: M. Di Nicolantonio, E. Rossi & T. Alexander (Eds.). Advances in additive manufacturing, modeling systems and 3D prototyping: Proceedings of the AHFE 2019 International Conference on Additive Manufacturing, Modeling Systems and 3D Prototyping, 2020 (pp. 279-288) Cham: Springer
The present work addresses two different applications enabled by a specific and useful property of calcium phosphate cements (CPCs): injectability. On the one hand minimally invasive procedures involving the use of CPCs are based on the injectability of such biomaterials, and on the other hand extrusion-based additive manufacturing processes such as robocasting rely on this property to correctly manufacture personalized 3D-printed scaffolds for the treatment of large bone defects. The present thesis is divided in three different sections. The first one consists in a study of the differences of injectability of aqueous pastes of the two allotropic forms of tricalcium phosphate, namely a- and ß-TCP. The reactivity of the powder was shown to play a significant role in the injectability of TCP pastes. Significant differences were observed between the injection behaviour of non-hardening ß-TCP pastes and that of selfhardening a-TCP pastes. The differences were more marked at low liquid-to-powder ratios, using fine powders and injecting through thin needles. Although, as a general trend, faster-setting pastes were less injectable, some exceptions to this rule were found. For example, whereas in the absence of setting accelerants fine TCP powders were more injectable than the coarse ones, in spite of their shorter setting times, this trend was inverted when setting accelerants were added, and coarse powders were more injectable than the fine ones. In the second section thermoresponsive pastes are developed through the combination of CPCs with an inversethermoresponsive hydrogel. Although calcium phosphate cements (CPCs) are used for bone regeneration in a wide range of clinical applications, various physicochemical phenomena are known to hinder their potential use in minimally invasive surgery or in highly vascularized surgical sites, mainly because of their lack of injectability or their low washout resistance. The proposed strategy allowed to finely tune the cohesive and rheological properties of CPCs to achieve clinical acceptable injectability. It avoided phase separation during implantation and improved cohesion, avoiding washout of the paste. Using the knowledge acquired about the injectability behaviour of TCP pastes, the additive manufacturing of 3D printed scaffolds is studied in the last section. More precisely, this study dealt with the robocasting of alpha-tricalcium phosphate/gelatine reactive slurries as a bioinspired self-setting ink for the production of biomimetic hydroxyapatite/gelatine scaffolds. A controlled and totally interconnected pore network of approximately 300 µm was obtained after ink printing and setting, with the struts consisting of a micro/nanoporous matrix of needle-shaped calcium deficient hydroxyapatite crystals, with a high specific surface area. Gelatine was effectively retained by chemical crosslinking. The setting reaction of the ink resulted in a significant increase of both the elastic modulus and the compressive strength of the scaffolds, which were within the range of the human trabecular bone. In addition to delaying the onset of the setting reaction, thus providing enough time for printing, gelatine provided the viscoelastic properties to the strands to support their own weight, and additionally enhanced mesenchymal stem cell adhesion and proliferation on the surface of the scaffold. Altogether this new processing approach opens good perspectives for the design of hydroxyapatite scaffolds for bone tissue engineering with enhanced reactivity and resorption rate.
El objetivo de esta tesis es el de la mejora del rendimiento de dispositivos electroquímcos miniaturizados, con énfasis en pilas de combustible microbianas y sensores electroquímicos. Para conseguir este objetivo, está tesis está centrada en el desarrollo de nuevos materiales para electrodos, nuevas geometrías para microelectrodos y mejor fabricación y procesos de encapsulado. Un inconveniente muy importante en la miniaturización de dispositivos electroquímicos está en la reducción de al superficie activa de los electrodos resultado en señales más pequeñas. Sin embargo, la introducción de técnicas de micromecanizado de silicio como pueden ser fotolitografía grabados seco y húmedo, deposición de metales o dieléctricos por métodos físicos o químicos o procesos térmicos rápidos se han convertido en una vía real para solventar todos los problemas relacionados la manufacturación de dispositivos electroquímicos miniaturizados. Además el uso de herramientas computacionales basadas en métodos de elementos finitos ha ayudado extraordinariamente al diseño de estos dispositivos porque la quinética del electrodo y el transporte de masa pueden ser simulados y estudiados antes de su fabricación. El primer capítulo es una introducción a los fundamentos de la electroquímica, al diseño, a la fabricación y a las aplicaciones desarrolladas en esta tesis. La primera sección se centra en explicar los aspectos fundamentales de la electroquímica. La segunda sección introduce las pilas de combustible, porque estos son los dispositivos electroquímicos desarrollados en el capítulo 4. Finalmente la última sección cubre los materiales y métodos utilizados, incluyendo la microfabricación de los electrodos y las técnicas de prototipaje utilizadas para fabricar las pilas de combustible microbianas. El segundo capítulo comienza con la teoría del transporte de masa en micropilares totalmente conductores. A continuación, el modelo computacional de un único dominio de un micropilar es desarrollado utilizando COMSOL. La fabricación de electrodos con arrays de micropilares totalmente conductores fue conseguida por electrodeposición de oro y también por la combinación de grabado seco y metalización por deposición de oro mediante sputtering. El capítulo cierra con la caracterización electroquímica de los dos arrays, lo que permitió comparar su respuesta y averiguar que ruta era la mejor. El capítulo tres se dirige a la síntesis y fabricación de discos de electrodos de carbón para detectar mercurio en muestras acuosas. Estos electrodos de carbón están basados en la pirólisis de fotoresina. Esta técnica combina fotolitografía y procesos térmicos rápidos. Además las ventanas activas de esos electrodos fueron definidas por deposición química de dieléctricos, también los electrodos fueron físicamente y electroquímicamente caracterizados. Una vez estos electrodos fueron completamente estudiados se utilizaron para detectar mercurio en soluciones. El último capítulo se centra en encontrar una aplicación a los electrodos de arrays de micropilares totalmente conductores. La aplicación escogida fue una pila de combustible microbiana miniaturizada fabricada mediante técnicas de prototipaje rápido, donde en cada caso una geometría diferente con el objeto de averiguar si los arrays de micropilares ayudan a mejorar el rendimiento eléctrico de las pilas de combustible microbianas.
In the the last decades several performance walls were hit. The memory wall and the power wall are limiting the performance scaling of digital microprocessors. Homogeneous multicores rely on thread-level parallelism, which is challenging to exploit. New heterogeneous architectures promise higher performance per watt rates, but software simulators have limited capacity to research them. In this thesis we investigate the advantages of Field-Programmable Gate Array devices (FPGA) for multicore research. We developed three prototypes, implementing up to 24 cores in a single FPGA, showing their superior performance and precision compared to software simulators. Moreover, our prototypes perform full-system emulation and are totally modifiable. We use our prototypes to implement novel architectural extensions such as Transactional Memory (TM). This use case allowed us to research different needs that computer architects may have, and how to implement them on FPGAs. We developed several techniques to offer profiling, debugging and verification techniques in each stage of the design process. These solutions may bridge the gap between FPGA-based hardware design and computer architects. In particular, we place a special stress on non-obtrusive techniques, so that the precision of the emulation is not affected. Based on the current trends and the sustained growth in the high-level synthesis community, we expect FPGAs to become an integral part of computer architecture design in the next years.
Geronazzo M, Vieira LS, Nilsson NC, Udesen J, and Serafin S
IEEE transactions on visualization and computer graphics [IEEE Trans Vis Comput Graph] 2020 May; Vol. 26 (5), pp. 1912-1922. Date of Electronic Publication: 2020 Feb 13.
Directivity and gain in microphone array systems for hearing aids or hearable devices allow users to acoustically enhance the information of a source of interest. This source is usually positioned directly in front. This feature is called acoustic beamforming. The current study aimed to improve users' interactions with beamforming via a virtual prototyping approach in immersive virtual environments (VEs). Eighteen participants took part in experimental sessions composed of a calibration procedure and a selective auditory attention voice-pairing task. Eight concurrent speakers were placed in an anechoic environment in two virtual reality (VR) scenarios. The scenarios were a purely virtual scenario and a realistic 360° audio-visual recording. Participants were asked to find an individual optimal parameterization for three different virtual beamformers: (i) head-guided, (ii) eye gaze-guided, and (iii) a novel interaction technique called dual beamformer, where head-guided is combined with an additional hand-guided beamformer. None of the participants were able to complete the task without a virtual beamformer (i.e., in normal hearing condition) due to the high complexity introduced by the experimental design. However, participants were able to correctly pair all speakers using all three proposed interaction metaphors. Providing superhuman hearing abilities in the form of a dual acoustic beamformer guided by head and hand movements resulted in statistically significant improvements in terms of pairing time, suggesting the task-relevance of interacting with multiple points of interests.
De Santis M, Storchi L, Belpassi L, Quiney HM, and Tarantelli F
Journal of chemical theory and computation [J Chem Theory Comput] 2020 Apr 14; Vol. 16 (4), pp. 2410-2429. Date of Electronic Publication: 2020 Mar 09.
We present a real-time time-dependent four-component Dirac-Kohn-Sham (RT-TDDKS) implementation based on the BERTHA code. This new implementation takes advantage of modern software engineering, including the prototyping techniques. The software design follows a three step approach: (i) the prototype implementation of a time-propagation algorithm in nonrelativistic real-time TDDFT within the Psi4NumPy framework, which provides a suitable environment for the creation of a clear, readable, and easy to test reference code in Python, (ii) the design of an original Python application programming interface for the relativistic four-component code BERTHA (PyBERTHA), which has an efficient computational kernel for relativistic integrals written in FORTRAN, and (iii) the porting of the time-propagation scheme enveloped within the Psi4NumPy framework to PyBERTHA. The propagation scheme consequently resides in a single readable Python computer code that is easy to maintain and in which the key quantities, such as the Dirac-Kohn-Sham and dipole matrices, can be accessed directly from the PyBERTHA module. For linear algebra operations (matrix-matrix multiplications and diagonalization) we use the highly optimized procedures implemented in the popular NumPy library. The overhead introduced by the Python interface to BERTHA is almost negligible (less than 1% evaluated on the SCF procedure), and the interoperability between different programming languages (FORTRAN, C, and Python) does not affect the numerical stability of the time-propagation scheme. Our new RT-TDDKS implementation has been employed to investigate the stability of the time-propagation procedure in combination with a density-fitting algorithm (both for the Coulomb and for the exchange-correlation matrix construction), which are employed in BERTHA to speed up the Dirac-Kohn-Sham matrix evaluation. On the basis of systematic calculations, employing several density-fitting basis sets of increasing accuracy, we showed that quantitative agreement can be achieved in combination with extended-fitting basis sets, with an error in the Coulomb energy below 1 μ-hartree. Convergence of the transition energies increasing of quality of the fitting basis sets has been also observed. Our data suggest that the error in the Coulomb energy may also represent a good estimate of the fitting basis set quality for real-time electron dynamics simulations. Further, we study the applicability of the RT-TDDKS method in combination with both weak- and extreme strong-field regime. Numerical results of excited-state transitions for the Group 12 atoms are reported and compared with a previous real-time Dirac-Kohn-Sham implementation (Repisky et al. J. Chem. Theory Comput. 2015, 11, 980-991). Finally, calculations of high harmonic generation in the hydrogen molecule and Au dimer have been also carried out. We were able to generate high harmonics with relatively well-defined peaks up to the 21st and 13th order in the case of H 2 and Au 2 , respectively. Our findings show that the four-component structure of the Dirac-Kohn-Sham Hamiltonian provides a suitable theoretical framework, with no intrinsic unfavorable features, to study molecules in the strong-field regime.
Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.] [J Esthet Restor Dent] 2020 Apr; Vol. 32 (3), pp. 265-271. Date of Electronic Publication: 2020 Feb 16.
Rodallec A, Franco C, Robert S, Sicard G, Giacometti S, Lacarelle B, Bouquet F, Savina A, Lacroix R, Dignat-George F, Ciccolini J, Poncelet P, and Fanciullino R
Scientific reports [Sci Rep] 2020 Mar 05; Vol. 10 (1), pp. 4147. Date of Electronic Publication: 2020 Mar 05.
Developing targeted nanoparticles is a rising strategy to improve drug delivery in oncology. Antibodies are the most commonly used targeting agents. However, determination of their optimal number at the surface remains a challenging issue, mainly due to the difficulties in measuring precisely surface coating levels when prototyping nanoparticles. We developed an original quantitative assay to measure the exact number of coated antibodies per nanoparticle. Using flow cytometry optimized for submicron particle analysis and beads covered with known amounts of human IgG-kappa mimicking various amounts of antibodies, this new method was tested as part of the prototyping of docetaxel liposomes coated with trastuzumab against Her2+ breast cancer. This quantification method allowed to discriminate various batches of immunoliposomes depending on their trastuzumab density on nanoparticle surface (i.e., 330 (Immunoliposome-1), 480 (Immunoliposome-2) and 690 (Immunoliposome-3), p = 0.004, One-way ANOVA). Here we showed that optimal number of grafted antibodies on nanoparticles should be finely tuned and highest density of targeting agent is not necessarily associated with highest efficacy. Overall, this new method should help to better prototype third generation nanoparticles.
Musiał J, Horiashchenko S, Polasik R, Musiał J, Kałaczyński T, Matuszewski M, and Śrutek M
Polymers [Polymers (Basel)] 2020 Apr 10; Vol. 12 (4). Date of Electronic Publication: 2020 Apr 10.
The original test results of abrasive wear resistance of different type of construction polymer materials were presented and discussed in this article. Tests were made on an adapted test stand (surface grinder for form and finish grinding). Test samples were made of different types of polymer board materials including RenShape®, Cibatool® and phenolic cotton laminated plastic laminate (TCF). An original methodology based on a grinding experimental set-up of abrasion wear resistance of polymer construction materials was presented. Equations describing relations between material type and wear resistance were presented and discussed. Micro and macro structures were investigated and used in wear resistance prediction.
Cao Y, Zhang W, Liang Y, Feng Z, Jiang C, Chen Z, and Jiang X
Computer assisted surgery (Abingdon, England) [Comput Assist Surg (Abingdon)] 2019 Dec; Vol. 24 (1), pp. 1-6. Date of Electronic Publication: 2019 Jan 21.
It is technically demanding and requires rich experience to insert the translaminar facet screw(TFS) via the paramedian mini-incision approach. It seems that it is easy to place the TFS using computer-assisted design and rapid prototyping(RP) techniques. However, the accuracy and safety of these techniques is still unknown. The aim of this study is to assess the accuracy and safety of translaminar facet screw placement in multilevel unilateral transforaminal lumbar interbody fusion using a rapid prototyping drill guide template system. A patient-matched rapid prototyping translaminar facet screw guide was examined in fourteen cadaveric lumbar spine specimens. A three-dimensional (3D) preoperative screw trajectory was constructed using spinal computed tomography scans, from which individualized guides were developed for the placement of translaminar facet screws. Following bone tunnel establishment, the 3D positioning of the entry point and trajectory of the screws was compared to the preoperative plan as found in the Mimics software.Among 60 trajectories eligible for assessment, no cases of clinically significant laminar perforation were found. The mean deviation between the planned and the actual starting points on spinous process was 1.22 mm. The mean tail and submergence angle deviation was found to be 0.68°and 1.46°, respectively. Among all the deviations, none were found to have any statistical significance. These results indicate that translaminar facet screw placement using the guide system is both accurate and safe.
Munoz-Guijosa JM, Zapata Martínez R, Martínez Cendrero A, and Díaz Lantada A
Materials (Basel, Switzerland) [Materials (Basel)] 2020 Feb 20; Vol. 13 (4). Date of Electronic Publication: 2020 Feb 20.
Advances in additive manufacturing technologies and composite materials are starting to be combined into synergic procedures that may impact the biomedical field by helping to achieve personalized and high-performance solutions for low-resource settings. In this article, we illustrate the benefits of 3D-printed rapid molds, upon which composite fibers can be laminated in a direct and resource-efficient way, for the personalized development of articular splints. The rapid mold concept presented in this work allows for a flexible lamination and curing process, even compatible with autoclaves. We demonstrate the procedure by completely developing an autoclave-cured carbon fiber-epoxy composite ankle immobilizing, supporting, or protecting splint. These medical devices may support patients in their recovery of articular injuries and for promoting a more personalized medical care employing high-performance materials, whose mechanical response is analyzed and compared to that of commercial devices. In fact, this personalization is fundamental for enhanced ergonomics, comfort during rehabilitation, and overall aesthetics. The proposed design and manufacturing strategies may support the low-cost and user-centered development of a wide set of biomedical devices and help to delocalize the supply chain for involving local populations in the development of medical technology.
ACS synthetic biology [ACS Synth Biol] 2020 Jan 17; Vol. 9 (1), pp. 144-156. Date of Electronic Publication: 2020 Jan 03.
The field of mammalian synthetic biology is expanding quickly, and technologies for engineering large synthetic gene circuits are increasingly accessible. However, for mammalian cell engineering, traditional tissue culture methods are slow and cumbersome, and are not suited for high-throughput characterization measurements. Here we have utilized mammalian cell-free protein synthesis (CFPS) assays using HeLa cell extracts and liquid handling automation as an alternative to tissue culture and flow cytometry-based measurements. Our CFPS assays take a few hours, and we have established optimized protocols for small-volume reactions using automated acoustic liquid handling technology. As a proof-of-concept, we characterized diverse types of genetic regulation in CFPS, including T7 constitutive promoter variants, internal ribosomal entry sites (IRES) constitutive translation-initiation sequence variants, CRISPR/dCas9-mediated transcription repression, and L7Ae-mediated translation repression. Our data shows simple regulatory elements for use in mammalian cells can be quickly prototyped in a CFPS model system.
ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2020 Jan 08; Vol. 12 (1), pp. 1817-1824. Date of Electronic Publication: 2019 Dec 19.
This paper presents a novel method of rapidly customizing microfluidic systems using a consumer-grade inkjet printer and a commercially available superhydrophobic spray. By casting polydimethylsiloxane (PDMS) on liquid templates that are defined by inkjet-printed hydrophilic patterns on superhydrophobically-coated PDMS substrates, microfluidic devices can be directly fabricated. Utilizing the interfacial properties of the superhydrophobic coating and the template liquid, the fabrication of microfluidics could be done with minimum effort and expertise, and unlike previously reported works, no mask and bonding process is necessary. As a proof of concept, we created different microfluidic devices for various applications, like gradient generation and pneumatic control of fluid. Appealing in its simplicity and rapidness, the newly proposed technique could provide an easy-to-use microfluidic platform for front-line researchers with different backgrounds to quickly customize microfluidic devices.
Oliveira B, Veigas B, Fernandes AR, Águas H, Martins R, Fortunato E, and Baptista PV
Sensors (Basel, Switzerland) [Sensors (Basel)] 2020 Mar 14; Vol. 20 (6). Date of Electronic Publication: 2020 Mar 14.
Microfluidic (MF) advancements have been leveraged toward the development of state-of-the-art platforms for molecular diagnostics, where isothermal amplification schemes allow for further simplification of DNA detection and quantification protocols. The MF integration with loop-mediated isothermal amplification (LAMP) is today the focus of a new generation of chip-based devices for molecular detection, aiming at fast and automated nucleic acid analysis. Here, we combined MF with droplet digital LAMP (ddLAMP) on an all-in-one device that allows for droplet generation, target amplification, and absolute quantification. This multilayer 3D chip was developed in less than 30 minutes by using a low-cost and extremely adaptable production process that exploits direct laser writing technology in "Shrinky-dinks" polystyrene sheets. ddLAMP and target quantification were performed directly on-chip, showing a high correlation between target concentration and positive droplet score. We validated this integrated chip via the amplification of targets ranging from five to 500,000 copies/reaction. Furthermore, on-chip amplification was performed in a 10 µL volume, attaining a limit of detection of five copies/µL under 60 min. This technology was applied to quantify a cancer biomarker, c-MYC , but it can be further extended to any other disease biomarker.
Roka-Moiia Y, Bozzi S, Ferrari C, Mantica G, Dimasi A, Rasponi M, Santoleri A, Scavone M, Consolo F, Cattaneo M, Slepian MJ, and Redaelli A
International journal of molecular sciences [Int J Mol Sci] 2020 Feb 11; Vol. 21 (4). Date of Electronic Publication: 2020 Feb 11.
As key cellular elements of hemostasis, platelets represent a primary target for thrombosis and bleeding management. Currently, therapeutic manipulations of platelet function (antithrombotic drugs) and count (platelet transfusion) are performed with limited or no real-time monitoring of the desired outcome at the point-of-care. To address the need, we have designed and fabricated an easy-to-use, accurate, and portable impedance aggregometer called "MICELI" (MICrofluidic, ELectrical, Impedance). It improves on current platelet aggregation technology by decreasing footprint, assay complexity, and time to obtain results. The current study aimed to optimize the MICELI protocol; validate sensitivity to aggregation agonists and key blood parameters, i.e., platelet count and hematocrit; and verify the MICELI operational performance as compared to commercial impedance aggregometry. We demonstrated that the MICELI aggregometer could detect platelet aggregation in 250 μL of whole blood or platelet-rich plasma, stimulated by ADP, TRAP-6, collagen, epinephrine, and calcium ionophore. Using hirudin as blood anticoagulant allowed higher aggregation values. Aggregation values obtained by the MICELI strongly correlated with platelet count and were not affected by hematocrit. The operational performance comparison of the MICELI and the Multiplate ® Analyzer demonstrated strong correlation and similar interdonor distribution of aggregation values obtained between these devices. With the proven reliability of the data obtained by the MICELI aggregometer, it can be further translated into a point-of-care diagnostic device aimed at monitoring platelet function in order to guide pharmacological hemostasis management and platelet transfusions.
De Vos J, Dams M, Broeckhoven K, Desmet G, Horstkotte B, and Eeltink S
Analytical chemistry [Anal Chem] 2020 Feb 04; Vol. 92 (3), pp. 2388-2392. Date of Electronic Publication: 2020 Jan 13.
A novel multilayer modulator chip offering a robust miniaturized interface for multidimensional liquid chromatography has been developed. The thermoplastic microfluidic device comprises five tailor-made functional layers, and the chip is compatible with commercially available switching-valve technology. The modulator chip allows for robust ultrahigh-pressure operation up to 65 MPa. Peak-dispersion characteristics of system peaks were assessed directly at the valve outlet by monitoring fluorescein injection profiles with laser-induced fluorescence detection. Integration of a microporous monolithic mixing entity in the microchannels significantly narrows the resulting peak profile. Proof-of-concept of the applicability of the microfluidic modulator chip is demonstrated in a heart-cut multidimensional strong-cation-exchange-reversed-phase liquid chromatography proteomics analysis workflow coupled to nanoelectrospray mass spectrometry for the target analysis of Glu-1-Fibrinopeptide B spiked in a protein digest mixture of bovine serum albumin.
Micromachines [Micromachines (Basel)] 2020 Jan 10; Vol. 11 (1). Date of Electronic Publication: 2020 Jan 10.
Microfluidic devices are gaining increasing popularity due to their wide applications in various research areas. Herein, we propose a two-layer multi-channel microfluidic device allowing for direct-contact cell-vessel co-culture. Using the device, we built a co-culture model of the outer blood-retina barrier (oBRB), mimicking the in vivo retinal pigment epithelial cells-Bruch membrane-fenestrated choroids. To demonstrate the versatility of the design, we further modified the device by inserting platinum electrodes for trans-epithelial electrical resistance (TEER) measurement, demonstrating the feasibility of on-chip assessment of the epithelial barrier integrity. Our proposed design allows for direct-contact co-culture of cell-cell or cell-vessel, modifiable for real-time evaluation of the state of the epithelial monolayers.