Core–Shell‐Heterostructured Magnetic–Plasmonic Nanoassemblies with Highly Retained Magnetic–Plasmonic Activities for Ultrasensitive Bioanalysis in Complex Matrix

Abstract

Herein, a facile self‐assembly strategy for coassembling oleic acid‐coated iron oxide nanoparticles (OC‐IONPs) with oleylamine‐coated gold nanoparticles (OA‐AuNPs) to form colloidal magnetic–plasmonic nanoassemblies (MPNAs) is reported. The resultant MPNAs exhibit a typical core–shell heterostructure comprising aggregated OA‐AuNPs as a plasmonic core surrounded by an assembled magnetic shell of OC‐IONPs. Owing to the high loading of OA‐AuNPs and reasonable spatial distribution of OC‐IONPs, the resultant MPNAs exhibit highly retained magnetic–plasmonic activities simultaneously. Using the intrinsic dual functionality of MPNAs as a magnetic separator and a plasmonic signal transducer, it is demonstrated that the assembled MPNAs can achieve the simultaneous magnetic manipulation and optical detection on the lateral flow immunoassay platform after surface functionalization with recognition molecules. In conclusion, the core–shell‐heterostructured MPNAs can serve as a nanoanalytical platform for the separation and concentration of target compounds from complex biological samples using magnetic properties and simultaneous optical sensing using plasmonic properties.

Functional Micro‐/Nanomaterials for Multiplexed Biodetection

“…The coexistence of excellent magnetic manipulation ability and strong optical signal makes these nanocomposites multifunctional labels in LFA to achieve an ultrasensitive detection of hepatitis C virus antibody (Figure 19B). [ 251 ] In addition to the core/shell structure, dumbbell‐like and flower‐like Au/Fe 3 O 4 composite nanomaterials can be prepared using the deposition–oxidation method. [ 252 ] Combination of plasmonic Au components and MNPs can act as separator and signal generator; moreover, they can also act separately.…”

“…B) Adapted under the terms of the CC‐BY Creative Commons Attribution 4.0 International license ( https://creativecommons.org/licenses/by/4.0). [ 251 ] Copyright 2019, The Authors, published by Wiley‐VCH. C) Reproduced with permission.…”

Magneto-Optical Nanostructures for Viral Sensing

“…Hao et al fabricated magnetic-plasmonic nano-assemblies with highly retained magnetic-plasmonic activities [ 51 ]. The concept was based on co-assembling oleic acid-coated MPs (OC-MPs) with oleylamine-coated Au NPs (OA-Au NPs) to form colloidal magnetic-plasmonic nano-assemblies exhibiting a typical core-shell heterostructure, comprising aggregated OA-Au NPs as a plasmonic core surrounded by an assembled magnetic shell of OC-MPs ( Figure 4 a).…”

“…It consists on the conjugation of carboxylated magneto-plasmonic nanostructures with hepatitis C virus antigen (HCV-antigen) via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated covalent coupling. The detection principle ( Figure 4 a) relies on capturing anti-HCV from serum samples on the particles, magnetic collection, and resuspending in phosphate-buffered saline (PBS) to run the LFIA test strip that was prepared by dispersing HCV antigen and goat-anti-mouse immunoglobuline G. The production of a red band at the T line was used for anti-HCV quantification [ 51 ]. This approach resulted in a detection limit of 0.24 pg mL −1 for anti-HCV.…”

“…Influenza virus A (H1N1) in deionized water was successfully detected with a detection limit of 7.27 fg/mL. a magneto-plasmonic particle, (ii) high-angle annular dark-field scanning transmission electron microscopy (HAADF-TEM) and energy-dispersive X-ray spectrometry (EDS) elemental mapping, (iii) HCV detection scheme based on anti-HCV modified MPs, followed by magnetic separation from the medium, addition to LFIA strip platform sensing using a double antigen sandwich lateral flow immunoassay (LFIA) strip platform (reprint from [51], with permission from Wiley, 2019 (b) TEM images of (i) graphene, (ii) graphene modified with gold nanoparticles (Au NPs) and MPs, (iii) Influenza virus detection scheme using antibody modified fluorescent quantum dots (QDs) for read out, (iv) Change of fluorescence intensity depending on virus concentration, (v) selectivity test against other influenza virus types (reprint from [11], with permission from Elsevier, 2018). HBV: hepatitis B virus.…”