Biocompatibility of nanoporous alumina membranes for immunoisolation

Flamme, Kristen E La; Popat, Ketul C.; Leoni, Lara; Markiewicz, Erica; Tempa, Thomas J. La; Roman, Brian B.; Grimes, Craig A.; Desai, Tejal A.

doi:10.1016/j.biomaterials.2007.02.010

Cited by 161 publications

(110 citation statements)

References 39 publications

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“…37,40,56 The second approach allows for considerably better control of the thickness and functionality of the formed coatings.…”

Section: Considerations In the Strategy For Surface Derivatizationmentioning

confidence: 99%

“…3,37,40,43,48,67 PEGylated surfaces demonstrate some of the highest protein resistance; they are relatively durable; and chemically, PEGs are relatively easy to manipulate. 40,52,58 Utilizing self-assembled monolayers (SAMs) of alkylthiols on gold surfaces for engineering of bioactive interfaces has gained significant popularity due to the simplicity of the used chemistry 45,74 and to the availability of high-resolution structural information for such SAMs. 80 Furthermore, engineering of bioactive interfaces over thin metal films has been a driving force for the development of biosensing applications based on surface plasmon resonance techniques.…”

Section: Introductionmentioning

confidence: 99%

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Surface-Bound Proteins with Preserved Functionality

et al. 2009

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Abstract-Biocompatibility of materials strongly depends on their surface properties. Therefore, surface derivatization in a controllable manner provides means for achieving interfaces essential for a broad range of chemical, biological, and medical applications. Bioactive interfaces, while manifesting the activity for which they are designed, should suppress all nonspecific interaction between the supporting substrates and the surrounding media. This article describes a procedure for chemical derivatization of glass and silicon surfaces with polyethylene glycol (PEG) layers covalently functionalized with proteins. While the proteins introduce the functionality to the surfaces, the PEGs provide resistance against nonspecific interactions. For formation of aldehyde-functionalized surfaces, we coated the substrates with acetals (i.e., protected aldehydes). To avoid deterioration of the surfaces, we did not use strong mineral acids for the deprotection of the aldehydes. Instead, we used a relatively weak Lewis acid for conversion of the acetals into aldehydes. Introduction of a,x-bifunctional polymers into the PEG layers, bound to the aldehydes, allowed us to covalently attach green fluorescent protein and bovine carbonic anhydrase to the surfaces. Spectroscopic studies indicated that the surface-bound proteins preserve their functionalities. The surface concentrations of the proteins, however, did not manifest linear proportionality to the molar fractions of the bifunctional PEGs used for the coatings. This finding suggests that surface-loading ratios cannot be directly predicted from the compositions of the solutions of competing reagents used for chemical derivatization.

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“…37,40,56 The second approach allows for considerably better control of the thickness and functionality of the formed coatings.…”

Section: Considerations In the Strategy For Surface Derivatizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface-Bound Proteins with Preserved Functionality

et al. 2009

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“…Recent studies related to the effect of nanotopography on cellular behavior indicated that osteoblast adhesion and functionality was enhanced by 30% when cultured on a nanograined Al 2 O 3 and TiO 2 substrate (4-6) compared with those cultured on a micrograined surface, and nanostructures such as TiO 2 nanotubes with Ͻ100-nm spacing showed superior characteristics in bone mineral synthesis (5). However, most of the previous studies on nanostructures and cell responses have mainly used oriented, patterned, or semiordered polymer arrays (7)(8)(9) and alumina/ polymer hybrid patterned arrays (10).…”

mentioning

confidence: 99%

Stem cell fate dictated solely by altered nanotube dimension

Oh¹,

Brammer²,

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

1,103

914

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Two important goals in stem cell research are to control the cell proliferation without differentiation and to direct the differentiation into a specific cell lineage when desired. Here, we demonstrate such paths by controlling only the nanotopography of culture substrates. Altering the dimensions of nanotubular-shaped titanium oxide surface structures independently allowed either augmented human mesenchymal stem cell (hMSC) adhesion or a specific differentiation of hMSCs into osteoblasts by using only the geometric cues, absent of osteogenic inducing media. hMSC behavior in response to defined nanotube sizes revealed a very dramatic change in hMSC behavior in a relatively narrow range of nanotube dimensions. Small (Ϸ30-nm diameter) nanotubes promoted adhesion without noticeable differentiation, whereas larger (Ϸ70-to 100-nm diameter) nanotubes elicited a dramatic stem cell elongation (Ϸ10-fold increased), which induced cytoskeletal stress and selective differentiation into osteoblast-like cells, offering a promising nanotechnology-based route for unique orthopedics-related hMSC treatments.differentiation ͉ mesenchymal ͉ nanotopography ͉ osteogenesis ͉ proliferation N anostructures are of particular interest because they have the advantageous feature of a high surface-to-volume ratio, and they elicit a higher degree of biological plasticity compared with conventional micro-or macrostructures. In the field of biomaterial development and in vivo implant technology, the nanoscale structure and morphologenic factor of the surface have played a critical role in accelerating the rate of cell proliferation and enhancing tissue acceptance with a reduced immune response (1, 2). In terms of in vitro cell biology, there has also been much attention placed on cellular responses to their structural surroundings (3). In fact, it has been observed that macro-, micro-and nano-sized topographical factors stimulate behavioral changes in both cells and tissues. Recent studies related to the effect of nanotopography on cellular behavior indicated that osteoblast adhesion and functionality was enhanced by 30% when cultured on a nanograined Al 2 O 3 and TiO 2 substrate (4-6) compared with those cultured on a micrograined surface, and nanostructures such as TiO 2 nanotubes with Ͻ100-nm spacing showed superior characteristics in bone mineral synthesis (5). However, most of the previous studies on nanostructures and cell responses have mainly used oriented, patterned, or semiordered polymer arrays (7-9) and alumina/ polymer hybrid patterned arrays (10).The material and mechanical characteristics of titanium (Ti) metal, which has a thin native oxide layer of TiO 2 , make it an ideal orthopedic material that bonds directly to the adjacent bone surface (11,12). Fabrication of the nanostructured titanium dioxide (TiO 2 ) nanotube arrays has been a primary subject of investigation lately because of the wide range of TiO 2 applications in the fields of solar cells (13-16), photocatalysis (17-19), photoelectrolysis (20), sensors (21,22), and b...

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“…Metallic films, with their distinct opacity toward visible light and adequate bandwidth across the entire visible spectrum, afford a better alternative. In this work, low-cost titanium and aluminum (with oxidized layer) were chosen for their biocompatible properties [29][30][31][32].…”

Section: Optical Characteristics Of Reaction Slidesmentioning

confidence: 99%

Improved picoliter-sized micro-reactors for high-throughput biological analysis

Han

Yuan

Wei

et al. 2013

Sci. China Life Sci.

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High-throughput pyrosequencing, carried out in millions of picoliter-sized reactors on a fiber-optic slide, is known for its longer read length. However, both optical crosstalk (which reduces the signal-to-noise ratio of CCD images) and chemical retention adversely affect the accuracy of chemiluminescence determination, and ultimately decrease the read length and the accuracy of pyrosequencing results. In this study, both titanium and oxidized aluminum films were deposited on the side walls and upper faces of micro-reactor slides to enhance optical isolation; the films reduced the inter-well crosstalk by one order of magnitude. Subsequently, chemical retention was shown to be caused by the lower diffusion coefficient of the side walls of the picolitersized reactors because of surface roughness and random pores. Optically isolated fiber-optic slides over-coated with silicon oxide showed smoother surface morphology, resulting in little chemical retention; this was further confirmed with theoretical calculations. Picoliter-sized micro-reactors coated with titanium-silicon oxide films showed the least inter-well optical crosstalk and chemical retention; these properties are expected to greatly improve the high-throughput pyrosequencing performance.high throughput analysis, picoliter-sized micro-reactor, surface coating Citation:Han W J, Yuan L N, Wei Q Q, et al. Improved picoliter-sized micro-reactors for high-throughput biological analysis.

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Biocompatibility of nanoporous alumina membranes for immunoisolation

Cited by 161 publications

References 39 publications

Surface-Bound Proteins with Preserved Functionality

Surface-Bound Proteins with Preserved Functionality

Stem cell fate dictated solely by altered nanotube dimension

Improved picoliter-sized micro-reactors for high-throughput biological analysis

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