title: Highly sensitive immunoassay based on SERS using nano-Au immune probes and a nano-Ag immune substrate.
abstract: A super-high-sensitivity immunoassay based on surface-enhanced Raman scattering (SERS) was implemented using the nano-Au immune probes and nano-Ag immune substrate. Ultraviolet-visible extinction spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, and SERS spectra were used to characterise the nano-Au immune probes and the nano-Ag immune substrate. The nano-Ag immune substrate was prepared by the in situ growth of Ag nanoparticles and the subsequent linkage of these nanoparticles with anti-apolipoprotein B on a silicon wafer. The nano-Ag immune substrate exhibited strong SERS activity, excellent reproducibility, and high biospecificity. The nano-Au immune probes were prepared by immobilising 4-mercaptobenzoic acid (4MBA) molecules as a Raman reporter and anti-apolipoprotein B onto the surfaces of Au nanoparticles. It was found that 4MBA induced the aggregation of Au nanoparticles, resulting in the generation of vast hot spots. Moreover, the nano-Au immune probes exhibited strong SERS activity and high biospecificity. A sandwich-type immunoassay structure consisting of the nano-Au immune probes and nano-Ag immune substrate was used to detect the concentration of apolipoprotein B, where the detection limit was as low as 2 fg/mL (3.878×10(-18) mol/L). Taken together, the experimental results indicate that the proposed immunoassay protocol has a great potential application in biological sensing and clinical diagnostics.
authors.affiliation: Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Shu
authors.affiliation: Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211, China. Electronic address: zhoujun@nbu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Institute of Micro & Nano Optics, Shenzhen University, Shenzhen 518060, China.
authors.forename: Xiaocong
authors.initials: X
authors.lastname: Yuan
authors.affiliation: Institute of Cybernetics "E. Caianiello" of CNR, Via Campi Flegrei 34, 80072 Pozzuoli, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Petti
authors.affiliation: Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 315211, China.
authors.forename: Jinping
authors.initials: J
authors.lastname: Chen
authors.affiliation: College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China.
authors.forename: Zhenhong
authors.initials: Z
authors.lastname: Jia
authors.affiliation: Institute of Cybernetics "E. Caianiello" of CNR, Via Campi Flegrei 34, 80072 Pozzuoli, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Mormile
mesh_terms: D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D001055:Apolipoproteins B / Q000032:analysis / Q000276:immunology; D001565:Benzoates / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D015203:Reproducibility of Results; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D000906:Antibodies; D001055:Apolipoproteins B; D001565:Benzoates; D013438:Sulfhydryl Compounds; C013594:4-mercaptobenzoate; D012834:Silver; D006046:Gold
keywords: Biosensing; Immunoassay; Nanoparticle; SERS substrate; Surface-enhanced Raman scattering