title: Electrochemical bioassay utilizing encapsulated electrochemical active microcrystal biolabels.
abstract: A new approach to perform electrochemical immunoassay based on the utilization of encapsulated microcrystal was developed. The microcrystal labels create a "supernova effect" upon exposure to a desired releasing agent. The microcrystal cores dissolve, and large amounts of signal-generating molecules diffuse across the capsule wall into the outer environment. Layer-by-Layer (LbL) technology was employed for the encapsulation of electrochemical signal-generating microcrystals (ferrocene microcrystals). The encapsulated microcrystals were conjugated with antibody molecules through the adsorption process. The biofunctionalized microcrystals were utilized as a probe for immunoassays. The microcrystal-based label system provided a high-signal molecule to antibody (S/P) ratio of 10(4)-10(5). Microcrystal biolabels with different antibody surface coverage (1.60-5.05 mg m(-2)) were subjected to a solid-phase immunoassay for the detection of mouse immunoglobulin G (M-IgG) molecules. The microcrystal-based immunoassay for the detection of M-IgG performed with microcrystals having antibody surface coverage of 5.05 mg m(-2) showed a sensitivity of 3.93 nA microg(-1) L(-1) with a detection limit of 2.82 microg L(-1).
authors.affiliation: Sino-German Nano-Analytical Laboratory, Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Wing Cheung
authors.initials: WC
authors.lastname: Mak
authors.forename: Kwan Yee
authors.initials: KY
authors.lastname: Cheung
authors.forename: Dieter
authors.initials: D
authors.lastname: Trau
authors.forename: Axel
authors.initials: A
authors.lastname: Warsinke
authors.forename: Frieder
authors.initials: F
authors.lastname: Scheller
authors.forename: Reinhard
authors.initials: R
authors.lastname: Renneberg
mesh_terms: D002214:Capsules / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D005296:Ferrous Compounds / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000032:analysis / Q000737:chemistry*; D000075163:Metallocenes; D008855:Microscopy, Electron, Scanning; D010316:Particle Size
chemical_list: D002214:Capsules; D005296:Ferrous Compounds; D007074:Immunoglobulin G; D000075163:Metallocenes; C004998:ferrocene