BIOSENSOR PROPERTIES OF PLASMONIC SILVER NANOPARTICLES PRODUCED BY PLD

Abstract

Plasmonic metal nanoparticles (NPs), such as Ag, Au, Cu NPs, attracts a lot of interest due to their notable applications in biological, and chemical sensing. Researchers have studied on plasmonic metal NPs which have exceptional optical properties in a large spectral region. Metal NPs form a unique surface plasmon resonance (SPR) peak that is in the electromagnetic spectrum’s visible part. The peak of SPR firmly depends on the NP’s size, shape, dielectric constant, and medium that the particle is in. Light interacts with nanoparticles that are smaller than the wavelength of incident light in localized surface resonance. That leads Localised Surface Plasmon Resonance (LSPR) in which an oscillating local plasma around NP with a certain frequency form. LSPR detection is the most common method for wavelength shift measurement. Analyte absorption causes a change in the local dielectric constant and thus LSPR peak shifts. Biological molecules such as proteins and antibodies can sensitively be detected as they change the local dielectric environment. Therefore, Ag or Au metal NPs can be used as sensor by employing LSPR wavelength shift technique. Among the metal NPs, Ag has a relatively higher refractive index sensitivity. Since Ag NPs have a shaper LSPR peak, they generate more precise measurements. In our work, we have produced plasmonic Ag NPs with various sizes and spherical shapes by employing Pulsed Laser Deposition (PLD). We investigated the LSPR peaks of produced plasmonic Ag NPs by UV-Vis spectroscopy. Moreover, biosensor properties of plasmonic Ag NPs are investigated by binding Protein A molecules to surface of the NPs. That produced a LSPR wavelength shift of around 100 nm/RIU.