BIOSENSOR PROPERTIES OF PLASMONIC SILVER NANOPARTICLES PRODUCED BY THE PLD MECHANISM

Özet

Plasmonic metal nanoparticles (NPs), such as Ag, Au, Cu NPs, attract great interest due to their notable applications in biological, and chemical sensing. Researchers have studied the 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 the NP with a certain frequency form. The LSPR detection is the most common method for wavelength shift measurement. Since analyte absorption causes a significant change on the value of local dielectric constant, the LSPR peak shifts. It is known that biological molecules such as proteins and antibodies can sensitively be detected while they affect the local dielectric environment. Therefore, Ag or Au based metal NPs can be used as a sensor with the help of LSPR wavelength shift technique. Among the metal NPs, Ag has a relatively higher refractive index sensitivity. Moreover, Ag NPs generate measurements that are more precise since they have a shaper LSPR peak. In our work, we produce plasmonic Ag NPs with various sizes and spherical shapes by making use of the Pulsed Laser Deposition (PLD) mechanism. Subsequently, we have investigate the LSPR peaks of these NPs via the UV-Vis spectroscopy. Additionally, biosensor properties of plasmonic Ag NPs are investigated by binding Protein A molecules to surface of the NPs. It is significant to mention here that we obtain an LSPR wavelength shift, which has a value around 100 nm/RIU.