TY - GEN A1 - Beisembek, Alisher A1 - Dimchevska Sazdovska, Simona A1 - Mirsky, Vladimir M. T1 - Separation of shifts in surface plasmon resonance into refractive index and thickness of deposited layers T2 - Sensors and actuators. B, Chemical N2 - Routine Surface Plasmon Resonance (SPR) measurements, which are widely applied in affinity (bio)sensors and surface science, do not allow one to separate the obtained SPR signals into the change of the refractive index and thickness of deposited layers. For thin layers the signal is proportional to the product of the layer thickness and the difference in the refractive indices of this layer and of the aqueous media. In this study, we suggest an approach to separate these parameters. It is performed by subsequent measurements in the presence and in the absence of polyethylene glycol (PEG), an inert additive which modifies the refractive index of the liquid phase but do not penetrate into the adsorbed layer. Both parameters were successively determined for human serum albumin (HSA) as well as for anti-HSA IgG in three different settings: i) HSA adsorbed directly onto a gold surface, ii) HSA chemically immobilized on a gold surface coated with a self-assembled monolayer of 1,16 mercaptohexadecanoic acid and iii) chemically immobilized HSA with additional monomolecular layer of anti- HSA IgG antibodies bond to this protein layer. The suggested approach can be applied in most SPR devices with a flow cell for analysis of various adsorbed layers. KW - Surface plasmon resonance KW - Thin layer thickness KW - Refractive index measurement Y1 - 2023 U6 - https://doi.org/10.1016/j.snb.2023.134606 SN - 1873-3077 SN - 0925-4005 VL - 396 ER - TY - GEN A1 - Nizamov, Shavkat A1 - Dimchevska Sazdovska, Simona A1 - Mirsky, Vladimir M. T1 - A review of optical methods for ultrasensitive detection and characterization of nanoparticles in liquid media with a focus on the wide field surface plasmon microscopy T2 - Analytica Chimica Acta N2 - Development of nanotechnology and corresponding industries during the last decade resulted in a new challenge for analytical science. This includes an ultrasensitive detection and characterization of nanoparticles of different origin and other nanomaterials in various media, including so complex ones as food, biological or environmental samples. The goal of this review is a systematic analysis of possible approaches and description of physical principles behind these methods. The main attention is paid to optical methods which are considered by authors to be mostly effective for the formulated task. Different approaches for detection and analysis of nanoparticles in a volume as well as of those adsorbed on a surface are discussed. While the technologies based on direct analysis of nanoparticle suspensions belong to the established approaches whose development potential has been in large extent exhausted, the novel technologies based on the surface sensing of adsorbed nanoparticles demonstrate intensive development. Therefore, the final part of the review is focused on the wide-field surface plasmon resonance microscopy. It allows one an ultrasensitive detection and characterization of individual nanoparticles of different origin in complex media and provides numerous possibilities for subsequent chemical identification of the detected particles using a hyphenation with other analytical technologies. KW - Nanoparticles KW - Detection of nanoparticles KW - Characterization of nanoparticles KW - Optical techniques KW - Surface plasmon resonance microscopy KW - Nanoparticle tracking analysis Y1 - 2022 U6 - https://doi.org/10.1016/j.aca.2022.339633 SN - 1873-4324 VL - 1204 ER -