title: Displacement-type quartz crystal microbalance immunosensing platform for ultrasensitive monitoring of small molecular toxins.
abstract: A novel displacement-type quartz crystal microbalance (QCM) immunosensing strategy, based on glucose and its analogue dextran for concanavalin A (ConA) binding sites, was designed for ultrasensitive monitoring of small molecular biotoxins (brevetoxin B, PbTx-2, used as a model) with signal amplification on a graphene-functionalized sensing interface. To construct such a QCM immunosensing platform, phenoxy-functionalized dextran (DexP) was initially assembled onto the surface of graphene-coated QCM probe via the π-stacking interaction, and ConA-labeled monoclonal mouse anti-PbTx-2 capture antibody was then immobilized on the DexP-modified probe by dextran-ConA binding. Gold nanoparticle heavily functionalized with glucoamylase and bovine serum albumin-PbTx-2 (PbTx-2-BSA) conjugate was employed as the trace tag. A competitive-type immunoassay format was adopted for the online monitoring of PbTx-2 between anti-PbTx-2 antibody immobilized on the QCM probe and PbTx-2-BSA labeled on the gold nanoparticle. Accompanying the gold nanoparticle, the carried glucoamylase could hydrolyze amylopectin in glucose. The produced glucose competed with dextran for ConA and displaced the ConA-streptavidin-anti-PbTx-2 complex from the QCM probe, resulting in the frequency change. Under optimal conditions, the frequency of the QCM immunosensor was indirectly proportional to the concentration of target PbTx-2 in the sample and exhibited a dynamic range from 1.0 pg·mL(-1) to 10 ng·mL(-1) with a detection limit (LOD) of 0.6 pg·mL(-1) at the 3Sblank level. Intra- and interassay coefficients of variation were below 7.5% and 9.5%, respectively. In addition, the methodology was evaluated for analysis of PbTx-2 in 15 spiked seafood samples and showed good accordance between results obtained by the displacement-type QCM immunosensor and a commercialized enzyme-linked immunosorbent assay (ELISA) method.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, People's Republic of China. dianping.tang@fzu.edu.cn
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Juan
authors.initials: J
authors.lastname: Tang
authors.forename: Li
authors.initials: L
authors.lastname: Hou
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D007118:Immunoassay / Q000379:methods; D008387:Marine Toxins / Q000032:analysis*; D051379:Mice; D035964:Oxocins / Q000032:analysis*; D058525:Quartz Crystal Microbalance Techniques / Q000379:methods*; D000095702:Polyether Toxins
chemical_list: D008387:Marine Toxins; D035964:Oxocins; C051732:Ptychodiscus brevis T2 toxin; C043466:brevetoxin B; D000095702:Polyether Toxins