High-throughput single-particle detections using a dual-height-channel-integrated pore.

We report a proof-of-principle demonstration of particle concentration to achieve high-throughput resistive pulse detections of bacteria using a microfluidic-channel-integrated micropore. We fabricated polymeric nanochannels to trap micrometer-sized bioparticles via a simple water pumping mechanism that allowed aggregation-free size-selective particle concentration with negligible loss. Single-bioparticle detections by ionic current measurements were then implemented through releasing and transporting the thus-collected analytes to the micropore.

Silicon substrate effects on ionic current blockade in solid-state nanopores.

We investigated the roles of silicon substrate material compositions in ionic current blockade in solid-state nanopores. When detecting single nanoparticles using an ionic current in a Si3N4 nanopore supported on a doped silicon wafer, resistive pulses were found to be blunted significantly via signal retardation due to predominant contributions of large capacitance at the ultrathin membrane. Unexpectedly, in contrast, changing the substrate material to non-doped silicon led to the sharpening of the spike-like signal feature, suggesting a better temporal resolution of the cross-channel ionic current measurements by virtue of the thick intrinsic semiconductor layer that served to diminish the net chip capacitance.

Electric field interference and bimodal particle translocation in nano-integrated multipores.

Parallel integration of multiple channels is a fundamental strategy for high-throughput particle detection in solid-state nanopores wherein understanding and control of crosstalk is an important issue for the post resistive pulse analysis. Here we report on a prominent effect of cross-channel electric field interference on the ionic current blockade by nanoparticles in nano-spaced pore arrays in a thin Si3N4 membrane. We systematically investigated the variations in resistive pulse profiles in multipore systems of various inter-channel distances.

Identifying Single Viruses Using Biorecognition Solid-State Nanopores.

Immunosensing is a bioanalytical technique capable of selective detections of pathogens by utilizing highly specific and strong intermolecular interactions between recognition probes and antigens. Here, we exploited the molecular mechanism in artificial nanopores for selective single-virus identifications. We designed hemagglutinin antibody mimicking oligopeptides with a weak affinity to influenza A virus.

Particle Capture in Solid-State Multipores.

Utilization of multiple-channel structure is a promising way of accomplishing high-throughput detections of analytes in solid-state pore sensors. Here we report on systematic investigation of particle capture efficiency in SiN multipore systems of various array configurations. We demonstrated enhanced detection throughput with increasing numbers of pore channels in a membrane.

Selective detections of single-viruses using solid-state nanopores.

Rapid diagnosis of flu before symptom onsets can revolutionize our health through diminishing a risk for serious complication as well as preventing infectious disease outbreak. Sensor sensitivity and selectivity are key to accomplish this goal as the number of virus is quite small at the early stage of infection. Here we report on label-free electrical diagnostics of influenza based on nanopore analytics that distinguishes individual virions by their distinct physical features.

Temporal Response of Ionic Current Blockade in Solid-State Nanopores.

Signal delay is a crucial factor in resistive pulse analyses using low-thickness-to-diameter aspect-ratio pores that aim to detect fine features in the ionic current blockade during the fast translocation of individual analytes to attain single-molecule tomography. Here we report on evaluations of the ionic current response to dynamic motions of nanoparticles in ultrathin solid-state nanopores. We systematically investigated the effects of pore resistance and membrane capacitance on resistive pulse waveforms under different salt concentration conditions and device configurations.

Identification of Individual Bacterial Cells through the Intermolecular Interactions with Peptide-Functionalized Solid-State Pores.

Bioinspired pore sensing for selective detection of flagellated bacteria was investigated. The Au micropore wall surface was modified with a synthetic peptide designed from toll-like receptor 5 (TLR5) to mimic the pathogen-recognition capability. We found that intermolecular interactions between the TLR5-derived recognition peptides and flagella induce ligand-specific perturbations in the translocation dynamics of Escherichia coli, which facilitated the discrimination between the wild-type and flagellin-deletion mutant (ΔfliC) by the resistive pulse patterns thereby demonstrating the sensing of bacteria at a single-cell level.

Discriminating single-bacterial shape using low-aspect-ratio pores.

Conventional concepts of resistive pulse analysis is to discriminate particles in liquid by the difference in their size through comparing the amount of ionic current blockage. In sharp contrast, we herein report a proof-of-concept demonstration of the shape sensing capability of solid-state pore sensors by leveraging the synergy between nanopore technology and machine learning. We found ionic current spikes of similar patterns for two bacteria reflecting the closely resembled morphology and size in an ultra-low thickness-to-diameter aspect-ratio pore.

A New In Vitro Co-Culture Model Using Magnetic Force-Based Nanotechnology.

Skeletal myoblast (SkMB) transplantation has been conducted as a therapeutic strategy for severe heart failure. However, arrhythmogenicity following transplantation remains unsolved. We developed an in vitro model of myoblast transplantation with "patterned" or "randomly-mixed" co-culture of SkMBs and cardiomyocytes enabling subsequent electrophysiological, and arrhythmogenic evaluation.

Cellular aggregate capture by fluidic manipulation device highly compatible with micro-well-plates.

This paper proposes a capture device to manipulate and transport a cellular aggregate in a micro-well. A cellular aggregate (a few hundreds μm in diameter) is currently manipulated by a pipette. The manual manipulation by a pipette has problems; low reliability, low throughput, and difficulty in confirmation of task completion.

Microfluidic devices for construction of contractile skeletal muscle microtissues.

Cell-culture microchips mimicking tissue/organ-specific functions are required as alternatives to animal testing for drug discovery and disease models. Although three-dimensional (3D) cell culture microfluidic devices can create more biologically relevant cellular microenvironments and higher throughput analysis platforms of cell behavior than conventional techniques, devices for skeletal muscle cells have not been developed. In the present study, we aimed to develop microfluidic devices for 3D cultures of skeletal muscle cells.

Parallel multipoint recording of aligned and cultured neurons on micro channel array toward cellular network analysis.

This paper describes an advanced Micro Channel Array (MCA) for recording electrophysiological signals of neuronal networks at multiple points simultaneously. The developed MCA is designed for neuronal network analysis which has been studied by the co-authors using the Micro Electrode Arrays (MEA) system, and employs the principles of extracellular recordings. A prerequisite for extracellular recordings with good signal-to-noise ratio is a tight contact between cells and electrodes.