Incorporation of Poly(ethylene glycol)-Proteins into Polymers

Panza, Janice L.; LeJeune, Keith E.; Venkatasubramanian, Srikanth; Russell, Alan J.

doi:10.1021/bk-1997-0680.ch009

Cited by 3 publications

(7 citation statements)

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Section: Discussionmentioning

confidence: 99%

“…Although these issues and others, such as mechanical stability and porosity remain to be properly addressed, the initial results are promising and suggest applications in the bio-catalyst, 3c,d,,,− biosensor, 3e,f, biodiagnostic, 3e,f, and combinatorial biocatalysis arenas. Indeed, results indicate that, at least for some proteins, the technique may provide useful “off the shelf” biocatalysts for synthetic transformations, ,− as well as extended stability biosensors. The accessibility of functionalized, multicomponent, and IPN composites should also lend this technique to producing micro/macrostructure arrays with catalytic/recognition features. 3e,f, Finally, polyol silicates/siloxanes may prove useful for assembling cell/tissue scaffolds, as well as the synthesis of controlled architectures via biomimetic and templating routes .…”

Section: Discussionmentioning

confidence: 99%

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Encapsulation of Biologicals within Silicate, Siloxane, and Hybrid Sol−Gel Polymers: An Efficient and Generic Approach

1998

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The sol−gel encapsulation of labile biological materials with catalytic and recognition functions within robust polymer matrices remains a challenging task, despite the considerable research that has been focused on this field. Herein, we describe a new class of precursors, based around polyol silicates and polyol siloxanes, especially those derived from glycerol, that addresses problems faced with traditional bioencapsulation protocols. Poly(glyceryl silicate) (PGS) was prepared and employed for sol−gel bioentrapment, in an approach distinguished by a high biocompatibility and mild encapsulation conditions, and which enables the reproducible and efficient confinement of proteins and cells inside silica. The methodology was extended to metallosilicate, alkylsiloxane, functionalized siloxane, and composite sol−gels, thereby allowing the fabrication of a physicochemically diverse range of bio-doped polymers. The hybrid materials display activities approaching those of the free biologicals, together with the high stabilities and robustness that characterize sol−gel bioceramics. Indeed, the bioencapsulates performed better than those fabricated from tetramethoxysilane, poly(methyl silicate) or alcohol-free poly(silicic acid), even when the latter were doped with glycerol. The activity enhancements appear to derive at least in part from the unusual microstructure of PGS sol−gels, in particular their high porosity, although the underlying mechanisms are unclear. Differences in precursor hydrolysis/condensation, development of gel structure, biological-matrix interactions, precursor toxicity, and pore collapse probably all contribute to the observed efficiency of the PGS materials. The performances of the encapsulates are compared with conventional sol−biogels and other immobilizates, in representative biocatalyst, biosensor, and biodiagnostic applications.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Encapsulation of Biologicals within Silicate, Siloxane, and Hybrid Sol−Gel Polymers: An Efficient and Generic Approach

1998

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“…Synthetic Applications. The reactions were conducted according to the published procedures, 4d, with some modifications as noted below. Adsorbates with lipase protein loads of 1−50 mg g -1 were prepared using 10 mg mL -1 (purified enzyme) or 30 mg mL -1 (crude enzyme) lipase stocks and then encapsulated (25% w/w of adsorbate, 55% w/w of PDMS mix, and 19% w/w of 4:1 PDES−PAPES cross-linker mix) according to the general procedure.…”

Section: Methodsmentioning

confidence: 99%

“…For (b) and (c), the catalysts were washed with dichloromethane saturated with phosphate buffer (0.1 M, pH 7.5, containing 30 mM calcium chloride and 10 mM magnesium chloride) between each recycle. The reactions were followed by RP-HPLC or chiral HPLC and product identities confirmed by comparison with standards. 4d, …”

Section: Methodsmentioning

confidence: 99%

“…A central requirement for consolidating biocatalysis as a standard synthetic tool is the development of immobilization methods capable of providing cheap, stable, and efficient heterogeneous biocatalysts. Although newer approaches such as sol−gel encapsulation, cross-linked crystals, and protein−polymer conjugates, ,, have gone some way toward addressing this issue, generic techniques capable of covering the wide spectrum of synthetically useful enzymes are still lacking. Herein we report a method for preparing highly active, stable, and reusable heterogeneous catalysts from one of the most exploited enzyme classes, namely, lipases, , based upon the formation of enzyme−silicone polymer composites.…”

Section: Introductionmentioning

confidence: 99%

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Lipase−Silicone Biocomposites: Efficient and Versatile Immobilized Biocatalysts

Gill¹,

Pastor²,

Ballesteros³

1999

J. Am. Chem. Soc.

103

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The last few decades have seen an explosion in the application of enzymes to organic chemistry, as these biological catalysts have continued to demonstrate their unique synthetic capabilities. Despite this, a key prerequisite for establishing enzymes as standard reagents in synthetic chemistry, specifically the availability of generic technologies providing inexpensive, robust, and reusable heterogeneous biological catalysts, still remains to be fulfilled. Herein, we describe a novel and highly efficient immobilization methodology for one of the most utilitarian classes of biocatalysts, namely, lipases. The procedure is based upon the adsorption of crude and pure lipases onto poly(hydroxymethylsiloxane), followed by the incorporation of the formed adsorbates into room-temperature vulcanizable silicones, to form biocatalytic composites. This provides hyperactivated catalysts showing activity enhancements of up to 54-fold as compared with the native enzymes, catalytic densities of up to several hundred kilo-units per gram of immobilizate, and high operational activity and stability in aqueous and organic media. The flexibility of silicone polymer chemistry enables the catalytic biocomposites to be prepared with a variety of physicochemistries, and to be fabricated as solid monoliths, sheets of thick films, particulates, and solid foams, thereby allowing the production of tailored catalysts for a variety of applications. The production and properties of a range of lipase−silicone composites are discussed, and the extended performances of selected catalysts are compared with those of the free enzymes and commercial heterogeneous biocatalysts in model synthetic reactions.

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Irreversible Immobilization of Diisopropylfluorophosphatase in Polyurethane Polymers

Drevon

Russell

2000

Biomacromolecules

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The synthesis of polyurethane polymers in the presence of diisopropylfluorophosphatase (DFPase) has enabled the irreversible attachment of the enzyme to the polymeric matrix. The resulting bioplastic hydrolyzes diisopropylfluorophosphate (DFP) in buffered media up to 67% of the rate for the same amount of soluble enzyme. Above a DFPase concentration of approximately 0.1 mg/gfoam, the rate of the reaction catalyzed by the enzyme-containing polymer was controlled by internal mass transfer. Increasing foam hydrophilicity, via the use of nonionic surfactants during polymerization, significantly affected the structural properties of matrix, thereby enhancing the intrinsic and apparent efficiency of modified DFPase. The resulting reduction in internal mass transfer limitations was explained morphologically with electron microscopy.

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Incorporation of Poly(ethylene glycol)-Proteins into Polymers

Cited by 3 publications

References 0 publications

Encapsulation of Biologicals within Silicate, Siloxane, and Hybrid Sol−Gel Polymers: An Efficient and Generic Approach

Encapsulation of Biologicals within Silicate, Siloxane, and Hybrid Sol−Gel Polymers: An Efficient and Generic Approach

Lipase−Silicone Biocomposites: Efficient and Versatile Immobilized Biocatalysts

Irreversible Immobilization of Diisopropylfluorophosphatase in Polyurethane Polymers

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