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Fluorescent microbeads hold great promise for in vivo continuous glucose monitoring with wireless transdermal transmission and long-lasting activity. The full potential of fluorescent microbeads has yet to be realized due to insufficient intensity for transdermal transmission and material toxicity. This paper illustrates the highly-sensitive, biostable, long-lasting, and injectable fluorescent microbeads for in vivo continuous glucose monitoring. We synthesized a fluorescent monomer composed of glucose-recognition sites, a fluorogenic site, spacers, and polymerization sites. The spacers are designed to be long and hydrophilic for increasing opportunities to bind glucose molecules; consequently, the fluorescent monomers enable high-intensive responsiveness to glucose. We then fabricated injectable-sized fluorescent polyacrylamide hydrogel beads with high uniformity and high throughput. We found that our fluorescent beads provide sufficient intensity to transdermally monitor glucose concentrations in vivo. The fluorescence intensity successfully traced the blood glucose concentration fluctuation, indicating our method has potential uses in highly-sensitive and minimally invasive continuous blood glucose monitoring. fluorescent hydrogel | microfluidics | diboronic acid | continuous glucose monitoring | diabetes mellitus doi/ 10.1073/pnas.1006911107

This paper describes a highly sensitive and selective chemical sensor using living cells (Xenopus laevis oocytes) within a portable fluidic device. We constructed an odorant sensor whose sensitivity is a few parts per billion in solution and can simultaneously distinguish different types of chemicals that have only a slight difference in double bond isomerism or functional group such as --OH, --CHO and -C/=O/-. We developed a semiautomatic method to install cells to the fluidic device and achieved stable and reproducible odorant sensing. In addition, we found that the sensor worked for multiple-target chemicals and can be integrated with a robotic system without any noise reduction systems. Our developed sensor is compact and easy to replace in the system. We believe that the sensor can potentially be incorporated into a portable system for monitoring environmental and physical conditions. fluidic channel | odorant receptor | robot | Xenopus oocyte doi/ 10.1073/pnas.1004334107

We present a microarray system that enables simultaneous monitoring of multiple ionic currents through transmembrane a-hemolysin nanopores arrayed at bilayer lipid membranes. We applied the self-assembling ability of lipid molecules interfaced between an aqueous solution and organic solvent to induce bilayer membrane formation at a microfluidic device; the device consists of a hydrophobic polymer film that serves to suspend the lipid-containing solvent at micrometer-sized apertures as well as to separate the aqueous solution into two chambers. In this study, we confirmed that expeditious and reproducible bilayer formation is realized by control of the composition of the solvent, a mixture of n-decane and 1-hexanol, which permits simultaneous incorporation of the a-hemolysin nanopores to the membrane array. Monitoring the eight wells on the array at once, we obtained a maximum of four relevant, synchronous signals of translocating ionic current through the nanopores. The system was also able to detect translocation events of nucleic acid molecules through the pore via the profile of a blocked current, promising its potential for high-throughput applications. 10.1021/ac901732z

This paper describes a multiwell biochip for simultaneous parallel recording of ion current through transmembrane pores reconstituted in planar lipid bilayer arrays. Use of a thin poly(p-xylylene) (parylene) film having micrometersized apertures ([theta] = 15-50 [micro]m, t = 20 [micro]m) led to formation of highly stable bilayer lipid membranes (BLMs) for incorporation of transmembrane pores; thus, a large number of BLMs could be arrayed without any skillful technique. We optically confirmed the simultaneous formation of BLMs in a 5 x 5 matrix, and in our durability test, the BLM lasted more than 15 h. Simultaneous parallel recording of alamethicin and gramicidin transmembrane pores in multiple contiguous recording sites demonstrated the feasibility of high-throughput screening of transmembrane ion currents in artificial lipid bilayers.

Dynamic microarrays hold great promise for advancing research in proteomics, diagnostics and drug discovery. However, this potential has yet to be fully realized due to the lack of reliable multi- functional platforms to transport and immobilize particles, infuse reagents, observe the reaction, and retrieve selected particles. We achieved all these functions in a single integrated device through the combination of hydrodynamic and optical approaches. Hydrodynamic forces allow simultaneous transportation and immobilization of large number of particles, whereas optical-based microbubble technique for bead retrieval gives dexterity in handling individual particles without complicated circuitry. Based on the criterion derived in this paper, the device was designed, and fabricated using standard photolithography and soft lithography methods. We examined the dynamics of bubble formation and dissipation in the device, and parametric studies revealed that higher power settings at short intervals were more efficient than low power settings at longer intervals for bead retrieval. We also demonstrated the capabilities of our device and its potential as a tool for screening methods such as the 'one-bead-one-compound' (OBOC) combinatorial library method. Although both approaches, hydrodynamic confinement and optical-based microbubbles, are presented in one device, they can also be separately used for other applications in microchip devices. high throughput screening | lab-on-a-chip | MEMS | bead-based assay | microbubble

Artificial planar lipid bilayers are a powerful tool for the functional study of membrane proteins, yet they have not been widely used due to their low stability and reproducibility. This paper describes an accessible method to form a planar lipid bilayer, simply by contacting two monolayers assembled at the interface between water and organic solvent in a microfluidic chip. The membrane of an organic solvent containing phospholipids at the interface was confirmed to be a bilayer by the capacitance measurement and by measuring the ion channel signal from reconstituted antibiotic peptides. We present two different designs for bilayer formation. One equips two circular wells connected, in which the water/solvent/water interface was formed by simply injecting a water droplet into each well. Another equips the cross-shaped microfluidic channel. In the latter design, formation of the interface at the sectional area was controlled by external syringe pumps. Both methods are extremely simple and reproducible, especially in microdevices, and will lead to automation and multiple bilayer formation for the high-throughput screening of membrane transport in physiological and pharmaceutical studies.

This paper describes the fabrication technology and characterization of Parylene neural probes containing fluidic channels for delivery of small amounts of drugs into biological tissue as well as neural recording. We present a first attempt to realize such neural probes by micromolding and thermal bonding of Parylene. Compared to the common fabrication method, where a sacrificial photoresist layer is sandwiched between two Parylene layers, the major advantages of this process are, that the time consuming photoresist dissolution is omitted, and that the adhesion between the Parylene Layers could be improved. The electrodes were characterized by impedance measurements, in which an impedance sufficiently low for neural recording was observed. Fluidic injection experiments with the microchannel have shown that nanoliter volumes can be injected. Index Terms--Microfluidic, neural probes, parylene, thermal bonding.

We propose an original approach to handle submicrometer-sized biological or inorganic materials in microfabricated devices for micro total analysis applications. Cellsized liposomes were utilized as containers for nanoparticles, green fluorescent proteins, or DNA and handled within a microfluidic chip. Due to the micrometer size of these liposomes, their detection could be achieved by conventional optical systems. Moreover, liposomes are hardly sensitive to Brownian motion; their trapping or transportation is thereby made easy with electrostatic-based techniques, for instance, developed the past few years for cells and particles. Encapsulated materials were confined for long durations with respect to the diffusive scale time, and the liposome membrane provided excellent protection from the outside environment, inhibiting undesirable interactions. A microfluidic device consisting of a flow cell covering an array of asymmetric electrodes allowed us to convey readily liposomes by the AC electroosmosis effect. We also assessed the electrofusion of liposomes between micromachined electrodes, opening up controlled initiation of reaction inside these containers; it was exemplified by fusing differently colored liposomes. We observed that a large fraction of the liposomes fused for electric field intensity around 6 kV/cm. Applications ranging from ultrasmall biomimetic reactors to large-scale drug delivery or cell labeling can be envisaged.

Author(s): Yannick Rondelez [1, 2]; Guillaume Tresset [1, 2]; Takako Nakashima [2]; Yasuyuki Kato-Yamada [3]; Hiroyuki Fujita [4]; Shoji Takeuchi [4]; Hiroyuki Noji (corresponding author) [2] F[sub.1] -ATPase is the [...]

We have demonstrated a novel micro/nanotransport system using biomolecular motors driven by adenosine triphosphate (ATP). For the driving mechanism, microtubule-kinesin system, which is one of the linear biomolecular motor systems was investigated. ATP dissolved in an aqueous condition is hydrolyzed to adenosine diphosphate (ADP) to energize the bionanoactuators in this mechanism. This means the system does not require an external electrical or mechanical energy source. Therefore, a purely chemical system which is similar to the in vivo transport will be realized. This paper reports some fundamental studies to integrate biomaterials and MEMS. The microtubules, or rail molecules, were patterned on a glass substrate with poly(dimethyl siloxane) (PDMS) using a regular soft lithography technique. Microbeads (320 nm in diameter) and a micromachined structure (2 x 3 [micro]m, 2 [micro]m in thickness) coated with kinesin molecules were transported along the microtubules at an average speed of 476 [+ or -] 56 and 308 nm/s, respectively. While ATP injection activated the transport system we have also managed to provide repetitive on/off control using hexokinase as an inhibitor. For the minimum response time in the repetitive control, the optimized concentration for ATP was [10.sup.2] [micro]M and [10.sup.3] U/L for hexokinase. [1107] Index Terms--Biomolecular motor, hybrid, kinesin, microtubule, transport.

A radio frequency (RF) telemetry system with a shape memory alloy microelectrode was designed and fabricated. The total size and weight are 15 mm x 8 mm and 0.1 g, respectively. Since the telemeter is small and light enough to be loaded on a small animal such as an insect, the system can be used for the neural recording of a freely moving insect. The RF-telemeter can transmit signals by frequency modulation transmission at 80-90 MHz. The transmitted signals can be received up to about 16 meters away from the telemeter with a high signal-to-noise ratio. The neural activity can be detected without attenuation by using an instrumentation amplifier with its input impedance set to 2 M[ohm] at 1 kHz. The telemeter was loaded on a cockroach and the neural activity during a free-walk was successfully measured through this telemetry system. Index Terms--FM transmitter, free-walking, insect, neural recording, RF-telemetry, wireless recording.

Author(s): Shoji Takeuchi (corresponding author) [1] Hydrogels are jelly-like materials that are made up of water-absorbing, 3D polymer networks. Their excellent properties, such as deformability, biocompatibility and diverse chemical functionalities, [...]

A method for the rapid exchange of buffer solution during single-molecule observation via use a simple, transparent, all-plastic one-way valve integrated on a coverslip on a flow cell is described. The performance of the valve formed by using a membrane made of parylene covering a microhole is explained based on the observations from response of a rotary biomotor, [F.sub.1]-ATPase, for several buffer solutions in the fabricated chamber.

A chemically engineered process is described after emulsification in order to form lipid vesiclelike compartments from emulsions. The studies have demonstrated the direct encapsulation of an aqueous solution into W/O/W vesicles with an extremely thin solvent layer.

The photophysical properties of tetra-tert-butylphthalocyaninatosilicon (SiPc) covalently linked to two 2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PROXYL) radicals (R2a) are examined in terms of the photocontrol of magnetic properties. The combination of electron paramagnetic resonance (EPR) and transient absorption measurements is used for the investigation.

The singlet oxygen [(super 1)delta(sub g)] generation mechanism using phthalocyaninatosilicon (SiPc) covalently linked to nitroxide radicals (NRs) is investigated. Experiments and theoretical analyses show that the spin-selective energy transfer rate constant is not influenced by linking the NRs and can be evaluated by the product of spin-statistical factors and matrix elements between the initial and final states.

A microelectrode, with clipping structure for neural recording from a free-moving insect, was designed and fabricated using a shape memory alloy (SMA) thin film. The SMA thin films (titanium nickel; Ti-48at.%Ni) are deposited by RF magnetron sputtering and patterned by HF-[HNO.sub.3] wet etching. The transformation temperatures of the SMA thin films were measured at 54 [degrees] C (A*) and 50 [degrees] C (M*). The SMA microelectrode consists of a [degrees] 'hook' structure (720 [micro]m x 480 [micro]m) and two 'C'-shape probes (600 [micro] m x 70 [micro] m). The electrode impedance is about 5 k [Omega] at at 1 kHz. The desired three-dimensional (3-D) shape is given to the electrode by a bonded wire. The clinging force of the electrode to the nerve is enhanced by the 3-D structures. The SMA microelectrode can clip a nerve cord tightly. The damages of the nerve by thermal actuation of the clip are not observed by physiological analysis. The neural activity from a living insect was successfully recorded with this SMA microelectrode. [423] Index Terms--Microelectrode, neural recording, SMA thin film.