Bioconjugation techniques for microfluidic biosensors
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We have evaluated five bioconjugation chemistries for immobilizing DNA onto silicon substrates for microfluidic biosensing applications. Conjugation by organosilanes is compared with linkage by carbonyldiimidazole (CDI) activation of silanol groups and utilization of dendrimers. Chemistries were compared in terms of immobilization and hybridization density, stability under microfluidic flow-induced shear stress, and stability after extended storage in aqueous solutions. Conjugation by dendrimer tether provided the greatest hybridization efficiency; however, conjugation by aminosilane treated with glutaraldehyde yielded the greatest immobilization and hybridization densities, as well as enhanced stability to both shear stress and extended storage in an aqueous environment. Direct linkage by CDI activation provided sufficient immobilization and hybridization density and represents a novel DNA bioconjugation strategy. Although these chemistries were evaluated for use in microfluidic biosensors, the results provide meaningful insight to a number of nanobiotechnology applications for which microfluidic devices require surface biofunctionalization, for example vascular prostheses and implanted devices.
KeywordsMicrofluidics/microfabrication Biosensors DNA immobilization Surface functionalization Bioconjugation Silane stability
Support for this work was provided by the National Institutes of Health-National Institute of Biomedical Imaging and Bioengineering (NIH-NIBIB) under grant number R21EB007031. This work made use of STC shared experimental facilities supported by the National Science Foundation under Agreement No. ECS-9876771. The authors gratefully acknowledge Dr. Sam Nugen and Prof. Antje Baeumner for technical assistance in determining hybridization conditions and Sudeep Mandal for preparation of PDMS master.
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