Hierarchical Fabrication of Plasmonic Superlattice Membrane by Aspect-Ratio Controllable Nanobricks for Label-Free Protein Detection

Abstract

Plasmonic superlattice membrane exhibits remarkable functional properties that are emerging from engineered assemblies of well-defined "meta-atoms," which is featured as a conceptual new category of two-dimensional optical metamaterials. The ability to build plasmonic membranes over macroscopic surfaces but with nanoscale ordering is crucial for systematically controlling the light-matter interactions and represents considerable advances for the bottom-up fabrication of soft optoelectronic devices and circuits. Through rational design, novel nanocrystals, and by engineering the packing orders, the hybridized plasmon signature can be customized, promoting controllable near-field confinement for surface-enhanced Raman scattering (SERS) based detection. However, building such 2D architectures has proven to be remarkably challenging due to the complicated interparticle forces and multiscale interactions during self-assembly. Here, we report on the fabrication of ultralong-nanobrick-based giant plasmonic superlattice membranes as high-performance SERS substrates for ultrasensitive and label-free protein detection. Using aspect-ratio controllable short-to-ultralong nanobricks as building blocks, we construct three distinctive plasmonic membranes by polymer-ligand-based strategy in drying-mediated self-assembly at the air/water interfaces. The plasmonic membranes exhibit monolayered morphology with nanoscale assembled ordering but macroscopic lateral dimensions, inducing enhanced near-field confinement and uniform hot-spot distribution. By choosing 4-aminothiophenol and bovine serum albumin (BSA) as a model analyte, we establish an ultrasensitive assay for label-free SERS detection. The detection limit of BSA can reach 15 nM, and the enhancement factor reached 4.3 × 10 5 , enabling a promising avenue for its clinical application in ultrasensitive biodiagnostics.

Plasmonic Superlattice Membranes Based on Bimetallic Nano-Sea Urchins as High-Performance Label-Free Surface-Enhanced Raman Spectroscopy Platforms

“…At last, the surface PS ligands of the fabricated plasmonic superlattice membranes were removed by O 2 plasma in order to eliminate their interference during the following SERS detection. As demonstrated by our previously reported paper, 11 the characteristic peak of PS ligands at about 1000 cm −1 almost disappeared after the plasma treatment, indicating high efficiency of the above ligand-removal technique.…”

“…The two-dimensional superlattice membrane is one of the typical thinnest possible metamaterials. 10,11 When the packing ordering and interparticle interactions of the constituent nanoparticles are adjusted, two-dimensional (2D) superlattice nanomembranes with desired plasmonic properties can be theoretically designed under the prediction of plasmon hybridization theory. 12,13 However, the assembly of these nanocrystals into highly ordered nanoscopic structures requires the integration of T h i s c o n t e n t i s nanometer-scale fabrication precision and top-down nanofabrication processes, 14 which is notoriously challenging due to complex interparticle forces.…”

“…The assembly of the plasmonic superlattice from different fundamental metallic entities inspires functionalities that exceed those of the individual subunits. The two-dimensional superlattice membrane is one of the typical thinnest possible metamaterials. , When the packing ordering and interparticle interactions of the constituent nanoparticles are adjusted, two-dimensional (2D) superlattice nanomembranes with desired plasmonic properties can be theoretically designed under the prediction of plasmon hybridization theory. , However, the assembly of these nanocrystals into highly ordered nanoscopic structures requires the integration of nanometer-scale fabrication precision and top-down nanofabrication processes, which is notoriously challenging due to complex interparticle forces. Particularly, rapid progress is seen in the precise regulation of the distinct pairwise interactions on demand during the superlattice formation by soft ligand modification, such as short surfactants, biomolecules, and polymeric shells, − which promises a controllable superlattice with improved performance for novel photonic devices.…”

Metal-Modified Montmorillonite as Plasmonic Microstructure for Direct Protein Detection

“…Such improvement enabled achieving single-molecule detection, which represents a hot topic in the field of DNA and protein sequencing when exploited to discriminate between single nucleic acid and amino acid of polymeric chains [ 16 , 52 , 53 ]. Among others, AgNP provides excellent resonance behaviors for amplifying the signal in the visible range and in comparison to gold nanoparticles, AgNPs allow achieving a stronger plasmonic enhancement due to lower interferences between intraband and interband electronic transition [ 54 ].…”

Gold Nanopolyhedron-Based Superlattice Sheets as Flexible Surface-Enhanced Raman Scattering Sensors for Detection of 4-Aminothiophenol

“…Distinct from their bulk counterparts or disordered clusters, emergent properties, and corresponding structure–function relationships of such well-defined superlattices are elucidated, such as the coherent vibrational modes, plasmon propagation, unique mechanical properties, , metal–insulator transition, p -type conductivities, and plasmon-driven catalytic properties, etc. By taking advantage of the strong coupling of metal nanoparticles with light at specific photon energies, enhanced light-matter interaction and electromagnetic field can be generated across the superlattices, which inspiring broad range of promising applications, including SERS based sensing and imaging, ,− flexible optoelectronics, energy harvest systems . However, it has proven to be remarkably difficult to build high-quality superlattices with macroscopic scale while maintaining nanoscopic ordering due to the complex interparticle forces during self-assembly …”