Surface Plasmon-Enhanced fluorescence of Spirulina microalgae via triangular silver nanoparticles

Abstract

This research focuses on improving the fluorescence properties of Spirulina microalgae by employing plasmonic nanoparticles (NPs). Spirulina is well-known for its natural chromophores, which present considerable opportunities for applications in photonics and biomedical imaging. The use of fluorescent dyes that attach to cancer cells is essential for differentiating malignant cells from healthy ones. Nevertheless, challenges such as low quantum yield, inner filter effects, and the aggregation of biocompatible pigments within solid matrices necessitate the implementation of enhancement techniques. The successful amplification of fluorescence through plasmonic metal NPs relies on the accurate alignment of the fluorescence emission spectrum with the plasmonic resonance (PR) spectrum of the NPs, as well as ensuring that the laser wavelength corresponds to the NP’s absorption spectrum. In this context, triangular silver nanoparticles (Ag-TNPs) have been selected due to their PR in the visible spectrum, which aligns effectively with the fluorescence spectrum of Spirulina. Additionally, the optimal concentration of NPs is critical. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses have demonstrated a higher likelihood of Ag-TNPs adhering to the surface of Spirulina microalgae at increased Ag-NP densities. Consequently, while Ag-TNPs exhibit a favorable PR at certain concentrations, excessive amounts can lead to induce weakening effects. Such a complex fluorescence behavior endorse ((Spirulina + Ag-TNP)) as a practical choice for developing biophotonic sensors that monitor changes in photoluminescence characteristics.