科研之友
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摘要
The use of silicon dioxide (SiO2) nanosprings as supports for immobilized enzymes in a continuous microreactor is described. A nanospring mat (2.2 cm(2) x 60 mu m thick) was functionalized with gamma-aminopropyltriethoxysilane, then treated with N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP) and dithiothreitol (DTT) to produce surface thiol (-SH) groups. SPDP-modified beta-galactosidase from Aspergillus oryzae was immobilized on the thiolated nanosprings by reversible disulfide linkages. The enzyme-coated nanospring mat was placed into a 175-mu m high microchannel, with the mat partially occluding the channel. The kinetics and steady-state conversion of hydrolysis of o-nitrophenyl beta-D-galactosylpyranoside at various substrate flow rates and concentrations were measured. Substantial flow was observed through the nanosprings, for which the Darcy permeability kappa approximate to 3 x 10(-6) cm(2). A simple, one-parameter numerical model coupling Navier-Stokes and Darcy flow with a pseudo-first-order reaction was used to fit the experimental data. Simulated reactor performance was sensitive to changes in kappa and the height of the nanospring mat. Permeabilities lower than 10(-8) cm(2) practically eliminated convective flow through the nanosprings, and substantially decreased conversion. Increasing the height of the mat increased conversion in simulations, but requires more enzymes and could cause sealing issues if grown above channel walls. Preliminary results indicate that in situ regeneration by reduction with DTT and incubation with SPDP-modified beta-galactosidase is possible. Nanosprings provide high solvent-accessible surface area with good permeability and mechanical stability, can be patterned into existing microdevices, and are amenable to immobilization of biomolecules. Nanosprings offer a novel and useful support for enzymatic microreactors, biosensors, and lab-on-chip devices.
- 出版日期2010-12
