Quantification of Metabolic Products from Microbial Hosts in Complex Media Using Optically Diffracting Hydrogels.

We herein describe a highly versatile platform approach for the in situ and real-time screening of microbial biocatalysts for enhanced production of bioproducts using photonic crystal hydrogels. This approach was demonstrated by preparing optically diffracting films based on polymerized -isopropylacrylamide that contracted in the presence of alcohols and organic acids. The hydrogel films were prepared in a microwell plate format, which allows for high-throughput screening, and characterized optically using a microwell plate reader.

Integrated Methods to Manufacture Hydrogel Microparticles with High Protein Conjugation Capacity and Binding Kinetics via Viral Nanotemplate Display.

Genetically modified tobacco mosaic virus (TMV) can serve as a potent nanotemplate for high capacity protein conjugation through covalent coupling to its coat proteins with precise nanoscale spacing. TMV's own genomic RNA can also be exploited for orientationally controlled assembly onto various platforms with sequence and spatial selectivity via nucleic acid hybridization. Here we describe detailed methods for fabrication of hydrogel microparticles with capture DNA sequences, chemical activation and programming of TMV templates, TMV assembly with the microparticles and protein conjugation via bio-orthogonal click reactions.

High-throughput double emulsion-based microfluidic production of hydrogel microspheres with tunable chemical functionalities toward biomolecular conjugation.

Chemically functional hydrogel microspheres hold significant potential in a range of applications including biosensing, drug delivery, and tissue engineering due to their high degree of flexibility in imparting a range of functions. In this work, we present a simple, efficient, and high-throughput capillary microfluidic approach for controlled fabrication of monodisperse and chemically functional hydrogel microspheres via formation of double emulsion drops with an ultra-thin oil shell as a sacrificial template. This method utilizes spontaneous dewetting of the oil phase upon polymerization and transfer into aqueous solution, resulting in poly(ethylene glycol) (PEG)-based microspheres containing primary amines (chitosan, CS) or carboxylates (acrylic acid, AA) for chemical functionality.

Remotely Triggered Locomotion of Hydrogel Mag-bots in Confined Spaces.

In this study, soft hydrogel crawlers with remote magnetic-responsive motility in confined spaces have been developed. Inspired by the motion of maggots, the hydrogel crawlers can reversibly contract and elongate their body controlled by repeatedly switching on/off an alternating magnetic field. Based on the cyclic deformation, the hydrogel crawlers can move peristaltically in a confined space that is coated with asymmetric micro-patterns.

Enhanced Optical Sensitivity in Thermoresponsive Photonic Crystal Hydrogels by Operating Near the Phase Transition.

Photonic crystal hydrogels composed of analyte-responsive hydrogels and crystalline colloidal arrays have immense potential as reagentless chemical and biological sensors. In this work, we investigated a general mechanism to rationally tune the sensitivity of photonic crystal hydrogels consisting of stimuli-responsive polymers to small molecule analytes. This mechanism was based on modulating the demixing temperature of such hydrogels relative to the characterization temperature to in effect maximize the extent of phase separation behavior; thus, the volume changes in response to the target analytes.

Improved Protein Conjugation with Uniform, Macroporous Poly(acrylamide-co-acrylic acid) Hydrogel Microspheres via EDC/NHS Chemistry.

We demonstrate a robust and tunable micromolding method to fabricate chemically functional poly(acrylamide-co-acrylic acid) (p(AAm-co-AA)) hydrogel microspheres with uniform dimensions and controlled porous network structures for rapid biomacromolecular conjugation. Specifically, p(AAm-co-AA) microspheres with abundant carboxylate functional groups are fabricated via surface-tension-induced droplet formation in patterned poly(dimethylsiloxane) molds and photoinduced radical polymerization. To demonstrate the chemical functionality, we enlisted rapid EDC/NHS (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS)) chemistry for fluorescent labeling of the microspheres with small-molecule dye fluorescein glycine amide.

Integrated fabrication-conjugation methods for polymeric and hybrid microparticles for programmable drug delivery and biosensing applications.

Functionalized polymeric microparticles possess significant potential for controlled drug delivery and biosensing applications, yet current fabrication techniques face challenges in simple and scalable fabrication and biofunctionalization. For programmable manufacture of biofunctional microparticles in a simple manner, we have developed robust micromolding methods combined with biopolymeric conjugation handles and bioorthogonal click reactions. In this focused minireview, we present detailed methods for our integrated approaches for fabrication of microparticles with controlled 2D and 3D shapes and dimensions toward controlled release, and for biomacromolecular conjugation via strain promoted alkyne-azide cycloaddition (SPAAC) and tetrazine-trans-cyclooctene (Tz-TCO) ligation reactions utilizing a potent aminopolysaccharide chitosan as an efficient conjugation handle.

Porosity-Tuned Chitosan-Polyacrylamide Hydrogel Microspheres for Improved Protein Conjugation.

We report a robust method to manufacture polyacrylamide-based functional hydrogel microspheres with readily tunable macroporous structures by utilizing a simple micromolding-based technique. Specifically, surface tension-induced droplet formation of aqueous solutions of chitosan and acrylamide in 2D-shaped micromolds followed by photoinduced polymerization leads to monodisperse microspheres. Pore sizes of the microspheres can be readily tuned by simple addition of inert long-chain poly(ethylene glycol) porogen at low content in the prepolymer solution.

Shape-Encoded Chitosan-Polyacrylamide Hybrid Hydrogel Microparticles with Controlled Macroporous Structures via Replica Molding for Programmable Biomacromolecular Conjugation.

Polymeric hydrogel microparticle-based suspension arrays with shape-based encoding offer powerful alternatives to planar and bead-based arrays toward high throughput biosensing and medical diagnostics. We report a simple and robust micromolding technique for polyacrylamide- (PAAm-) based biopolymeric-synthetic hybrid microparticles with controlled 2D shapes containing a potent aminopolysaccharide chitosan as an efficient conjugation handle uniformly incorporated in PAAm matrix. A postfabrication conjugation approach utilizing amine-reactive chemistries on the chitosan shows stable incorporation and retained chemical reactivity of chitosan, readily tunable macroporous structures via simple addition of low content long-chain PEG porogens for improved conjugation capacity and kinetics, and one-pot biomacromolecular assembly via bioorthogonal click reactions with minimal nonspecific binding.

Gintonin stimulates gliotransmitter release in cortical primary astrocytes.

Lysophosphatidic acid (LPA) is a simple and minor phospholipid, but serves as a lipid-derived neurotransmitter via activation of G protein-coupled LPA receptors. Astrocytes abundantly express LPA receptors and contain gliotransmitters that modulate astrocyte-neuron interactions. Gintonin is a novel ginseng-derived G protein-coupled LPA receptor ligand.

An integrated approach for enhanced protein conjugation and capture with viral nanotemplates and hydrogel microparticle platforms via rapid bioorthogonal reactions.

We demonstrate significantly enhanced protein conjugation and target protein capture capacity by exploiting tobacco mosaic virus (TMV) templates assembled with hydrogel microparticles. Protein conjugation results with a red fluorescent protein R-Phycoerythrin (R-PE) show significantly enhanced protein conjugation capacity of TMV-assembled particles (TMV-particles) compared to planar substrates or hydrogel microparticles. In-depth examination of protein conjugation kinetics via tetrazine (Tz)-trans-cyclooctene (TCO) cycloaddition and strain-promoted alkyne-azide cycloaddition (SPAAC) reaction demonstrates that TMV-particles provide a less hindered environment for protein conjugation.

Facile strategy for protein conjugation with chitosan-poly(ethylene glycol) hybrid microparticle platforms via strain-promoted alkyne-azide cycloaddition (SPAAC) reaction.

We demonstrate a facile fabrication-conjugation scheme for protein-conjugated biosensing platforms. Specifically, we utilize a chitosan-poly(ethylene glycol) hybrid system to fabricate highly uniform and chemically reactive microparticle platforms via simple replica molding. Strain-promoted alkyne-azide cycloaddition (SPAAC) reaction between azide-modified proteins and microparticles activated with strain-promoted cyclooctynes allows tunable protein conjugation under mild reaction conditions.

Current stimulator IC with adaptive supply regulator for visual prostheses.

The current stimulation method is preferred over the voltage stimulation method in the visual prostheses based on functional electrical stimulation (FES) due to its accurate charge control property. Previous current stimulators are generally implemented using a static high supply voltage, because current stimulations require high output voltage compliance. This high static supply voltage, however, may harm the tissues or damage the electrodes.

Multi-channel stimulator IC using a channel sharing method for retinal prostheses.

A retinal stimulator is an implantable device restoring vision by supplying a controlled, stimulating electrical signal to people blinded by retinal diseases such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). The resolution requirements of artificial retina systems become increasingly significant in their design as well as their usefulness. At least 32 x 32 pixels are required to provide a minimal visual function.

Fabrication of chitosan-poly(ethylene glycol) hybrid hydrogel microparticles via replica molding and its application toward facile conjugation of biomolecules.

We demonstrate a facile scheme to fabricate nonspherical chitosan-poly(ethylene glycol) (PEG) microparticle platforms for conjugation of biomolecules with high surface density. Specifically, we show that PEG microparticles containing short chitosan oligomers are readily fabricated via replica molding (RM). Fluorescence and FTIR microscopy results illustrate that these chitosan moieties are incorporated with PEG networks in a stable manner while retaining chemical reactivity toward amine-reactive chemistries.

Measurements of serum C-reactive protein levels in patients with gastric cancer and quantification using silicon nanowire arrays.

Unlabelled: We examined the levels of serum alpha-fetoprotein, carcinoembryonic antigen, and carbohydrate antigen in 83 of 400 patients who had undergone surgery for gastric cancer and correlated these markers with stages of the disease. In addition, we measured C-reactive protein (CRP) concentrations in the sera of gastric cancer patients with silicon nanowire field-effect transistors (SiNW FETs) to determine whether SiNW FETs could be used to accurately sense CRP, a marker of inflammation and possible indicator of future progression of the cancer. We designed and fabricated SiNWs to be responsive to CRP.

Quantitative measurements of C-reactive protein using silicon nanowire arrays.

A silicon nanowire-based sensor for biological application showed highly desirable electrical responses to either pH changes or receptor-ligand interactions such as protein disease markers, viruses, and DNA hybridization. Furthermore, because the silicon nanowire can display results in real-time, it may possess superior characteristics for biosensing than those demonstrated in previously studied methods. However, despite its promising potential and advantages, certain process-related limitations of the device, due to its size and material characteristics, need to be addressed.

Fabrication of suspended silicon nanowire arrays.

A method to fabricate suspended silicon nanowires that are applicable to electronic and electromechanical nanowire devices is reported. The method allows for the wafer-level production of suspended silicon nanowires using anisotropic etching and thermal oxidation of single-crystal silicon. The deviation in width of the silicon nanowire bridges produced using the proposed method is evaluated.

Hard X-ray microscopy with Zernike phase contrast.

Zernike phase contrast has been added to a full-field X-ray microscope with Fresnel zone plates that was in operation at 6.95 keV. The spatial resolution has also been improved by increasing the magnification of the microscope objective looking at the CsI(Tl) scintillation crystal.

Observations of a human hair shaft with an x-ray microscope.

We observed the internal structures of a human hair shaft using x-ray microscopes with a spatial resolution in the range from a few microns to less than 100 nm. The energy of the x-ray used is 6.95 keV.