Plasmonic enhanced fluorescence (PEF) technology is a powerful strategy to improve the sensitivity of immunofluorescence microarrays (IFMA), however, current approaches to constructing PEF platforms are either expensive/time-consuming or reliant on specialized instruments. Here, we develop a completely alternative approach relying on a two-step protocol that includes the self-assembly of gold nanoparticles (GNPs) at the water–oil interface and subsequent annealing-assisted regulation of gold nanogap. Our optimized thermal-annealing GNPs (TA-GNP) platform generates adequate hot spots, and thus produces high-density electromagnetic coupling, eventually enabling 240-fold fluorescence enhancement of probed dyes in the near-infrared region. For clinical detection of human samples, TA-GNP provides super-high sensitivity and low detection limits for both hepatitis B surface antigen and SARS-CoV-2 binding antibody, coupled with a much-improved detection dynamic range up to six orders of magnitude. With fast detection, high sensitivity, and low detection limit, TA-GNP could not only substantially improve the outcomes of IFMA-based precision medicine but also find applications in fields of proteomic research and clinical pathology.

Gold nanoring arrays are widely applied in various fields benefitting from their localized surface plasmon resonance (LSPR) properties. A key advantage of gold nanoring arrays is that the dipole resonance peak can be systematically tuned by changing the dimensions of gold nanoring arrays. However, most of the currently reported methods for preparing gold nanoring arrays cannot conveniently control the heights of the nanorings at a low cost. Here we introduce a facile method for preparing gold nanoring arrays with tunable plasmonic resonances using colloidal lithography. The dimensions of the nanorings including diameters, lattice constants, even the heights of the nanorings can be conveniently varied. Fourier transform near-infrared (FT-NIR) absorption spectroscopy was used to obtain the plasmonic resonance spectra of the nanoring arrays. All the prepared gold nanoring arrays exhibited a strong NIR or infrared (IR) plasmonic resonance which can be tuned by varying the nanoring dimensions. This versatile method can also be used to fabricate other types of plasmonic nanostructures, such as gold nanocone arrays. The obtained gold nanoring arrays as well as nanocone arrays may have potential applications in surface-enhanced spectroscopy or plasmonic sensing.

In this paper, we report a new strategy for the fabrication of gold nanoring arrays via colloidal lithography and polymer-assisted self-assembly of gold nanoparticles (Au NPs). First, multi-segmented polymer nanorod arrays were fabricated via colloidal lithography. They were then used as templates for Au NP adsorption, which resulted in nanoparticles on the poly(4-vinyl pyridine) (P4VP) segments. Continuous gold nanorings were formed after electroless deposition of gold. The diameter, quantity, and spacing of the gold nanorings could be tuned. Three dimensional coaxial gold nanorings with varying diameters could be fabricated on a polymer nanorod by modifying the etch parameters. The nanorings exhibited optical plasmonic resonances at theoretically predicted wavelengths. In addition, the polymer-assisted gold nanorings were released from the substrate to generate a high yield of free-standing nanorings. This simple, versatile method was also used to prepare nanorings from other metals such as palladium.

We demonstrate a facile method combining colloidal lithography, selective ion-exchange, and the in situ reduction of Ag ions (Ag⁺) for the fabrication of multi-segmented barcode nanorods. First, polymer multilayer films were prepared by spin-coating alternating thin films of polystyrene and polyacrylic acid (PAA), and then multi-segmented polymer nanorods were fabricated via reactive ion etching with colloidal masks. Second, Ag nanoparticles (Ag NPs) were incorporated into the PAA segments by an ion exchange and the in situ reduction of the Ag⁺. The selective incorporation of the Ag NPs permitted the modification of the specific bars of the nanorods. Lastly, the Ag NP/polymer composite nanorods were released from the substrate to form suspensions for further coding applications. By increasing the number of segments and changing the length of each segment in the nanorods, the coding capacity of nanorods was improved. More importantly, this method can easily realize the density tuning of Ag NPs in different segments of a single nanorod by varying the composition of the PAA segments. We believe that numerous other coded materials can also be obtained, which introduces new approaches for fabricating barcoded nanomaterials.