Simulation of Highly Sensitive Multi-Core-Satellite Plasmonic Structures for Detection of Gastric Cancer Agent MicroRNA-21 Using Modified Discrete Dipole Approximation

Using the modified discrete dipole approximation (DDA) method, the absorption spectrum of the multi-core-satellite structures (which are formed by connecting plasmonic nanoparticles by two probe molecules and one microRNA-21 molecule) was investigated. Two spherical and chain models were considered for the connection of the plasmonic nanoparticles. The results showed that using the chain connection model of nanoparticles leads to the formation of multiple absorption peaks, which we classified in the three wavelength regions, the short, the middle, and the long region. The three regions was 350 to 500 nm, 500 to 650 nm, and 650 to 800 nm for silver-based structures and 500 to 600 nm, 600 to 700 nm, and 700 to 800 nm for gold based structures. Due to the large number of peaks, the wavelength of the peak with the highest intensity was examined in each region. The superposition of spectra of the different structures can lead to the formation of broad peaks at longer wavelengths, which is in agreement with the previously published experimental results.