Plasmonic ELISA Research Articles

Plasmonic ELISA for the detection of gp120 at ultralow concentrations with the naked eye.

The technique of plasmonic ELISA is utilised here to detect the HIV-1 protein gp120 with the ultralow limit of detection of 8 × 10(-20) M (10(-17) g mL(-1)) in an independent laboratory. It was corroborated that changes in the concentration of hydrogen peroxide as small as 0.05 μM could lead to nanoparticle solutions of completely different tonality.

Plasmonic ELISA for the detection of analytes at ultralow concentrations with the naked eye

This protocol describes a signal-generation mechanism for the naked-eye detection of analytes at low concentrations with ELISA. The key step is to generate solutions of desired tonality by growing gold nanoparticles with a particular state of aggregation. This is accomplished by linking the growth of gold nanoparticles with the biocatalytic cycle of the enzyme label. The protocol adapts a conventional ELISA procedure with catalase-labeled antibodies. The enzyme consumes hydrogen peroxide, and then gold (III) ions are added to generate gold nanoparticles. The concentration of hydrogen peroxide dictates the state of aggregation of gold nanoparticles. This allows for the naked-eye detection of analytes by observing the generation of blue- or red-colored gold nanoparticle solutions. When coupled with conventional ELISA, this signal-generation procedure allows for the naked-eye detection of analytes within 1 h.

Arresting the time-dependent H2O2 mediated synthesis of gold nanoparticles for analytical detection and preparative chemistry.

The time-dependent progression from gold nanosponges (AuNS) to discrete small gold nanoparticles (AuNPs) mediated by H2O2 in MES buffer is blocked by the addition of a thiol, glutathione. This represents an important improvement for the plasmonic ELISA, and also leads to a time-dependent approach for the synthesis of AuNS and AuNPs in water with precise control over nanostructure size.