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).

Electrochemical Sensors

“…163 The microcrystal core was encapsulated with an ultrathin and porous polymeric capsule conjugated with antibody. The crystal can dissolve immediately and release large amounts of signal generating molecules.…”

Nanoparticle‐Based Electrochemical Bioassays of Proteins

“…Other marker encapsulation routes hold great promise for electrochemical bioassays. Particularly attractive are the recently developed nanoencapsulated microcrystalline particles, prepared by the layer-by-layer (LBL) assembly technique, that offer large marker/biomolecule ratios and superamplified bioassays [48,49].…”

Multifunctional protein particles with dual analytical channels for colorimetric enzymatic bioassays and fluorescent immunoassays

“…Performing analytical measurements using miniaturized systems, such as microparticles have attracted great interest in various applications such as medical diagnostics (Mak et al, 2005(Mak et al, , 2011Xiang et al, 2011;Zhang et al, 2011) environmental monitoring (Kim et al, 2008;Ramon-Azcon et al, 2009), chemical processes (Mak et al, 2008a) and biological system monitoring (Fischer et al, 2009). …”