Abstract
Microelectrode arrays (MEAs) provide promising opportunities to study electrical signals in neuronal and cardiac cell networks, restore sensory function, or treat disorders of the nervous ...system. Nevertheless, most of the currently investigated devices rely on silicon or polymer materials, which neither physically mimic nor mechanically match the structure of living tissue, causing inflammatory response or loss of functionality. Here, we present a new method for developing soft MEAs as bioelectronic interfaces. The functional structures are directly deposited on PDMS-, agarose-, and gelatin-based substrates using ink-jet printing as a patterning tool. We demonstrate the versatility of this approach by printing high-resolution carbon MEAs on PDMS and hydrogels. The soft MEAs are used for in vitro extracellular recording of action potentials from cardiomyocyte-like HL-1 cells. Our results represent an important step toward the design of next-generation bioelectronic interfaces in a rapid prototyping approach.
Background Clinical immunology has traditionally relied on accurate phenotyping of the patient's immune dysfunction for the identification of a candidate gene or genes for sequencing and molecular ...confirmation. Although this is also true for other branches of medicine, the marked variability in immune-related phenotypes and the highly complex network of molecules that confer normal host immunity are challenges that clinical immunologists often face in their quest to establish a specific genetic diagnosis. Objective We sought to identify the underlying genetic cause in a consanguineous family with chronic inflammatory bowel disease–like disorder and combined immunodeficiency. Methods We performed exome sequencing followed by autozygome filtration. Results A truncating mutation in LPS-responsive beige-like anchor ( LRBA ), which abolished protein expression, was identified as the most likely candidate variant in this family. Conclusion The combined exome sequencing and autozygosity mapping approach is a powerful tool in the study of atypical immune dysfunctions. We identify LRBA as a novel immunodeficiency candidate gene the precise role of which in the immune system requires future studies.
Recent investigations into cardiac or nervous tissues call for systems that are able to electrically record in 3D as opposed to 2D. Typically, challenging microfabrication steps are required to ...produce 3D microelectrode arrays capable of recording at the desired position within the tissue of interest. As an alternative, additive manufacturing is becoming a versatile platform for rapidly prototyping novel sensors with flexible geometric design. In this work, 3D MEAs for cell-culture applications were fabricated using a piezoelectric inkjet printer. The aspect ratio and height of the printed 3D electrodes were user-defined by adjusting the number of deposited droplets of silver nanoparticle ink along with a continuous printing method and an appropriate drop-to-drop delay. The Ag 3D MEAs were later electroplated with Au and Pt in order to reduce leakage of potentially cytotoxic silver ions into the cellular medium. The functionality of the array was confirmed using impedance spectroscopy, cyclic voltammetry, and recordings of extracellular potentials from cardiomyocyte-like HL-1 cells.
Adams-Oliver syndrome (AOS) is defined by the combination of aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). It is usually inherited as an autosomal-dominant trait, but ...autosomal-recessive inheritance has also been documented. In an individual with autosomal-recessive AOS, we combined autozygome analysis with exome sequencing to identify a homozygous truncating mutation in dedicator of cytokinesis 6 gene (DOCK6) which encodes an atypical guanidine exchange factor (GEF) known to activate two members of the Rho GTPase family: Cdc42 and Rac1. Another homozygous truncating mutation was identified upon targeted sequencing of DOCK6 in an unrelated individual with AOS. Consistent with the established role of Cdc42 and Rac1 in the organization of the actin cytoskeleton, we demonstrate a cellular phenotype typical of a defective actin cytoskeleton in patient cells. These findings, combined with a Dock6 expression profile that is consistent with an AOS phenotype as well as the very recent demonstration of dominant mutations of ARHGAP31 in AOS, establish Cdc42 and Rac1 as key molecules in the pathogenesis of AOS and suggest that other regulators of these Rho GTPase proteins might be good candidates in the quest to define the genetic spectrum of this genetically heterogeneous condition.
We investigate the influence of self-assembled alkanethiol monolayers at the surface of platinum microelectrode arrays on the stochastic amperometric detection of citrate-stabilized silver ...nanoparticles in aqueous solutions. The measurements were performed using a microelectrode array featuring 64 individually addressable electrodes that are recorded in parallel with a sampling rate of 10 kHz for each channel. We show that both the functional end group and the total length of the alkanethiol influence the charge transfer. Three different terminal groups, an amino, a hydroxyl, and a carboxyl, were investigated using two different molecule lengths of 6 and 11 carbon atoms. Finally, we show that a monolayer of alkanethiols with a length of 11 carbon atoms and a carboxyl terminal group can efficiently block the charge transfer of free nanoparticles in an aqueous solution.
Hereditary Spastic Paraplegia (HSP) is a clinically and genetically heterogeneous group of neurological disorders that are characterized by progressive spasticity of the lower extremities. We ...describe an extended consanguineous Saudi family in which HSP is linked to SPG18, a previously reported autosomal recessive locus, and show that it is associated with a nullimorphic deletion of
ERLIN2
, a component of endoplasmic reticulum associated degradation. This finding adds to the growing diversity of cellular functions that are now known to be involved in the maintenance of the corticospinal tract neurons.
Primordial dwarfism (PD) is a phenotype characterized by profound growth retardation that is prenatal in onset. Significant strides have been made in the last few years toward improved understanding ...of the molecular underpinning of the limited growth that characterizes the embryonic and postnatal development of PD individuals. These include impaired mitotic mechanics, abnormal IGF2 expression, perturbed DNA-damage response, defective spliceosomal machinery, and abnormal replication licensing. In three families affected by a distinct form of PD, we identified a founder truncating mutation in POC1A. This gene is one of two vertebrate paralogs of POC1, which encodes one of the most abundant proteins in the Chlamydomonas centriole proteome. Cells derived from the index individual have abnormal mitotic mechanics with multipolar spindles, in addition to clearly impaired ciliogenesis. siRNA knockdown of POC1A in fibroblast cells recapitulates this ciliogenesis defect. Our findings highlight a human ciliopathy syndrome caused by deficiency of a major centriolar protein.
Solid-phase isothermal DNA amplification was performed exploiting the homology protein recombinase A (recA). The system was primarily tested on maleimide activated microtitre plates as a ...proof-of-concept and later translated to an electrochemical platform. In both cases, forward primer for Francisella tularensis holarctica genomic DNA was surface immobilised via a thiol or an amino moiety and then elongated during the recA mediated amplification, carried out in the presence of specific target sequence and reverse primers. The formation of the subsequent surface tethered amplicons was either colorimetrically or electrochemically monitored using a horseradish peroxidase (HRP)-labelled DNA secondary probe complementary to the elongated strand. The amplification time was optimised to amplify even low amounts of DNA copies in less than an hour at a constant temperature of 37°C, achieving a limit of detection of 1.3×10–13M (4×106 copies in 50μL) for the colorimetric assay and 3.3×10–14M (2×105 copies in 10μL) for the chronoamperometric assay. The system was demonstrated to be highly specific with negligible cross-reactivity with non-complementary targets or primers.
•Development of a gold genosensor for rapid detection of a Francisella tularensis genomic DNA sequence.•The detection strategy is based on the isothermal solid-phase amplification using a recombinase polymerase enzyme and label-based end-point electrochemical detection.•The system demonstrates high specificity with negligible cross-reactivity, achieving a limit of detection of 2×105 copies in 10μL.
A simple lab-on-a-chip method for blood plasma separation was developed by combining stereolithographic 3D printing with inkjet printing, creating a completely sealed microfluidic device. In some ...approaches, one dilutes the blood sample before separation, reducing the concentration of a target analyte and increasing a contamination risk. In this work, a single drop (8 μl) of heparinized whole blood could be efficiently filtered using a capillary effect without any external driving forces and without dilution. The blood storage in heparin tubes during 24 h at 4 °C initiated the formation of small crystals that formed auto-filtration structures in the sample upon entering the 3D-printed device, with pores smaller than the red blood cells, separating plasma from the cellular content. The total filtration process took less than 10 s. The presented printed plasma filtration microfluidics fabricated with a rapid prototyping approach is a miniaturized, fast and easy-to-operate device that can be integrated into healthcare/portable systems for point-of-care diagnostics.
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