ABSTRACT
The unprecedented materialistic and optoelectronic properties of various nanomaterials, including nanoparticles (NPs), render them suitable for further exploration as label-free sensing tools with improved sensitivity or specificity and vast applications in medicine, including point-of-care diagnostics. Nanomaterials, including various NPs, offer exciting opportunities for developing biosensors that are fast, robust, and highly efficient. Gold NPs (AuNPs) have emerged as the foremost candidate of the family of NPs from noble metals for biosensing purposes. The bigger AuNPs scatter more due to a larger scattering cross section. Aggregation of AuNPs causes a red-shift of the localized surface plasmon resonance (LSPR) spectrum due to the fact that with aggregation, more delocalized surface plasmons are shared between neighboring particles, which decreases the energy required for LSPR. Red-shift of the LSPR in AuNPs occurs as the refractive index of the surrounding medium increases, and vice versa. The shape of AuNPs is an important attribute in determining the LSPR.
