One way to improve the sensitivity and throughput of miniaturized biomolecular assays is to integrate microfluidics to enhance the transport efficiency of biomolecules to the reaction sites. Such microfluidic integration requires bonding of a prefabricated microfluidic gasket to an assay surface without destroying its biological activity. In this paper we address the largely unmet challenge to accomplish a proper seal between a microfluidic gasket and a protein surface, with maintained biological activity and without contaminating the surface or blocking the microfluidic channels. We introduce a novel dual cure polymer resin for the formation of microfluidic gaskets that can be room-temperature bonded to a range of substrates using only UVA light. This polymer is the first polymer that features over a month of shelf life between the structure formation and the bonding, moreover the fully cured polymer gaskets feature the following set of properties suitable for microfluidics: high stiffness, which prevents microfluidic channel collapse during handling; very limited absorption of biomolecules; and no significant leaching of uncured monomers. We describe the novel polymer resin and its characteristics, study through FT-IR, and demonstrate its use as microfluidic well-arrays bonded onto protein array slides at room temperature followed by multiplexed immunoassays. The results confirm maintained biological activity and show high repeatability between protein arrays. This new approach for integrating microfluidic gaskets to biofunctionalised surfaces has the potential to improve sample throughput and decrease manufacturing costs for miniaturized biomolecular systems.
We here demonstrate, for the first time, the use of direct lithography in off-stoichiometry thiol-ene-epoxy (OSTE+) to fabricate a microdevice. First, the photolithographic property of OSTE+ is shown by using a photomask to create micropillars with an aspect-ratio of 1:10 in a 2 mm thick layer. Secondly, a three-layer OSTE+ microdevice containing in-/outlet holes, channels, and pillars is fabricated by using a combination of direct lithography and adhesive-free dry bonding. The resulting microdevice shows desirable properties, such as leak-free filling and hydrophilic surfaces. This fabrication method enhances the microstructurability of OSTE+ beyond that of conventional soft lithography replica molding of other polymers, such as PDMS.
Cover: Confocal image of primary human cardiac fibroblasts in culture. Focus on Fibroblasts: Development, plasticity, and therapeutic challenges in the cardiac fibroblast lineage THESIS FOR DOCTORAL DEGREE (Ph.D.
Nano-ball allophane is a naturally occurring aluminum silicate mineral with hollow spherical morphology. Diameter of the mineral is observed as 3.5 to 5.0 nm with TEM, and cation exchange experiments have proven the existence of some pores along the spherule wall. Chemical structure of the wall is similar to that of imogolite with nano-tube structure, where orthosilicates are bonded inside of gibbsite vacant site (imogolite sheet). However, whole chemical structure of the nano-ball has not been clarified. We succeeded to tentatively construct the whole chemical structure of the ball by assuming an expanded truncated octahedron composed of hexagonal imogolite sheets. By changing size of the imogolite sheets, diameters of the ball become 1.5 nm, 3.0 nm, 4.5 nm, and so on. Here we present full-structural optimization results for the nano-ball with diameter of 1.5 nm. Gaussian 03 for UNIX revision C.01 with HF/6-31G(d) method was used for calculations. The 6-coordinated Al and the 4-coordinated Si atom in the optimized structure were stable and no change in its ball shape structure. The calculated O O atom distance in the vacant octahedral site that is substituted with orthosilicate has average 2.62 Å. Meanwhile, in the outer vacant octahedral sheet, the distance has average value of 4.25 Å for. It can be said that these contractions from substituted Si atom cause transformation of a planar gibbsite sheet to a material with spherical shape. Until now, there are no reports on the evidence of smallest nano-ball allophane except with diameter of 3.5 to 5.0 nm. However, our calculation result confirmed that the smallest of nano-ball allophane is stable and possible exists in the soil natural environmental.
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