title: Electric-field-directed self-assembly of active enzyme-nanoparticle structures.
abstract: A method is presented for the electric-field-directed self-assembly of higher-order structures composed of alternating layers of biotin nanoparticles and streptavidin-/avidin-conjugated enzymes carried out on a microelectrode array device. Enzymes included in the study were glucose oxidase (GOx), horseradish peroxidase (HRP), and alkaline phosphatase (AP); all of which could be used to form a light-emitting microscale glucose sensor. Directed assembly included fabricating multilayer structures with 200 nm or 40 nm GOx-avidin-biotin nanoparticles, with AP-streptavidin-biotin nanoparticles, and with HRP-streptavidin-biotin nanoparticles. Multilayered structures were also fabricated with alternate layering of HRP-streptavidin-biotin nanoparticles and GOx-avidin-biotin nanoparticles. Results showed that enzymatic activity was retained after the assembly process, indicating that substrates could still diffuse into the structures and that the electric-field-based fabrication process itself did not cause any significant loss of enzyme activity. These methods provide a solution to overcome the cumbersome passive layer-by-layer assembly methods to efficiently fabricate higher-order active biological and chemical hybrid structures that can be useful for creating novel biosensors and drug delivery nanostructures, as well as for diagnostic applications.
authors.affiliation: Department of Bioengineering, University of California San Diego, La Jolla, CA 92093-0412, USA.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Hsiao
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Heller
mesh_terms: D001360:Avidin / Q000737:chemistry / Q000378:metabolism; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D001710:Biotin / Q000737:chemistry / Q000378:metabolism; D004574:Electromagnetic Fields; D005947:Glucose / Q000032:analysis; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism; D056656:Lab-On-A-Chip Devices; D008165:Luminol / Q000737:chemistry / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D019809:Streptavidin / Q000737:chemistry / Q000378:metabolism
chemical_list: D001360:Avidin; D008165:Luminol; D001710:Biotin; D019809:Streptavidin; D005949:Glucose Oxidase; D005947:Glucose