title: CB[7]-mediated signal amplification approach for sensitive surface plasmon resonance spectroscopy.
abstract: Cucurbit[7]uril (CB[7]) has received increasing attention because of its unique structure and multiple recognition properties. To improve the sensitivity of surface plasmon resonance (SPR) biosensors, we designed a novel strategy in which caspase-3 serves as the model analyte and CB[7]-modified AuNPs (CB[7]-AuNPs) act as the intermedium. The substrate peptides can be cleaved and replaced with a new N-terminal Phe residue in presence of caspase-3. The CB[7]-AuNPs combine with the N-terminal Phe on the gold chip surface through incorporating the side chain within the nonpolar CB[7] cavity and chelating the N-terminal ammonium group with CB[7] carbonyl oxygen. Then CB[7]-AuNPs integrate with short peptide-modified AuNPs containing Phe at the N-terminal of the peptide. SPR signals are significantly improved through the layer-by-layer assembly of AuNPs. The well-designed sensing platform allows the detection of caspase-3 in a linear range from 10fg/mL to 10(3)fg/mL with a detection limit of 2.2 fg/mL. Given its high specificity and desirable sensitivity, this CB[7]-assisted SPR method may be a useful tool for the assay of caspase-3 in the future. This work may also afford a new model to improve the sensitivity and selectivity of SPR biosensors in other protein detection experiments and disease diagnosis.
authors.affiliation: Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Zou
authors.affiliation: Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
authors.forename: Beiping
authors.initials: B
authors.lastname: Wu
authors.affiliation: Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China; Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
authors.forename: Xingxin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Lab for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, PR China.
authors.forename: Jiangjiang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Institute of General Education, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Kwangnak
authors.initials: K
authors.lastname: Koh
authors.affiliation: Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China. Electronic address: hxchen@shu.edu.cn.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Chen
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry*; D053148:Caspase 3 / Q000032:analysis*; D057075:Enzyme Assays / Q000379:methods; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007093:Imidazoles / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D011994:Recombinant Proteins / Q000032:analysis; D020349:Surface Plasmon Resonance / Q000379:methods*; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D053148:Caspase 3; D006046:Gold; D007093:Imidazoles; D011994:Recombinant Proteins; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
keywords: Caspase-3; Cucurbit[7]uril; Gold nanoparticles; Signal amplification; Surface plasmon resonance