Enzyme-catalyzed silver deposition on irregular-shaped gold nanoparticles for electrochemical immunoassay of alpha-fetoprotein

Nanomaterials for early detection of cancer biomarker with special emphasis on gold nanoparticles in immunoassays/sensors

“…Shape and size of AuNPs are the important structural factors to be considered in any assay/ sensor. In comparison to spherical AuNPs, the assays using irregular shaped AuNPs (ISNGSs) -anti-AFP-HRP as trace labels exhibited higher bioelectrocatalytic response towards enzyme substrate (Tang et al, 2010;Lai et al, 2012). When AuNPs in support with other nanomaterials including multiwalled carbon nanotubes (MWCNTs) were used as carriers of enzymes, the sensitivity of CL assays improved (Lai et al, 2009;Tang et al, 2011;Cao et al, 2012;Akter et al, 2012).…”

Recent Advances in Nanoparticles-based Lateral Flow Biosensors

“…Due to low abundance of targets, high sensitivity is highly desired for LFBs. An effective way for improving the sensitivity of the GNPs-based bioassay is to amplify the Au signal by adopting silver enhancement technology to the traditional bioassay [75][76][77][78][79][80][81]. Under the action of the reducing agent, silver ions is prone to gather around the GNPs in the form of silver, the color of the test zone is greatly enhanced due to the silver deposition on the GNPs surface.…”

Multiplexed electrochemical immunoassay using streptavidin/nanogold/carbon nanohorn as a signal tag to induce silver deposition

“…With the development of nanoscience and nanotechnology, various nanomaterial-based tracing tags have been designed to amplify the electrochemical signal and develop ultrasensitive immunoassay methods [14]. The most popular strategy is performed by conjugating large amounts of signal molecules such as enzymes [15,16], electroactive molecules [17] and metallic nanoparticles [18,19] on various nanocarriers, including carbon nanotubes [20,21], graphene [22], magnetic beads [23], nanoparticles [10,24] and mesoporous materials [25]. Single-walled carbon nanohorn (SWCNH), a dahlia flowerlike nanostructure composed of thousands of graphitic tubule closed ends [26,27], possesses unique features of large surface area, plentiful inner nanospaces, highly defective horns, and good electrical conductivity [28,29], and has been used as an excellent nanocarrier to load high amount of gold nanoparticles (AuNPs) for signal amplification [19].…”

“…Different from the stripping analysis of quantum dots (QD) for enzyme-free electrochemical immunoassay [30,31], the stripping analysis of metallic nanoparticles, such as AuNPs [19,32] and silver nanoparticles (AgNPs) [16,[33][34][35][36], can be performed by their direct electrochemical oxidiation in HCl to produce a detectable signal [14]. In comparison with AuNPs, AgNPs can be electrochemically oxidized at a relatively negative potential with a relatively sharp peak, thus, they are the more favorable signal tag than AuNPs.…”