ИСТИНА

We will survey the main trends in photothermal and photoacoustic spectroscopies related, directly or indirectly, to analytical chemistry and applied chemical analysis of biomedical and technological samples. Since the 1980s, these methods had been used in various analytical applications including highly sensitive photometric optical measurements and versatile detection schemes. Still, their potentialities in (bio)analytical chemistry grow wider. Particular attention will be given to the coupling of photothermal spectroscopy to other analytical techniques and advances over conventional methods. As photothermal and photoacoustic spectroscopies are ‘not just highly sensitive photometry’, their field of application for heterogeneous materials (solid or liquid), including dynamically appearing and changing heterogeneities, develops rapidly. The examples will include the formation of nanoparticles, crystalline and amorphous residues and protein-lipid complexes. Photothermics shows wide potentialities both for the determining the absorption-band parameters of proteins and for detecting laser-induced photochemical reactions; high precision of the measurements of absorption spectra is observed both in solutions and in cellular structures. The application of photothermal spectroscopy for the quantification, size estimation of heme proteins and carbon nanomaterials will be discussed. The examples of multi-wavelength photothermal and photoacoustic imaging and determination of carbon nanomaterials and heme proteins will be discussed. Some examples of new relevant analytical applications based on well-known and novel selective photometric reactions will be given, especially those of optical chemical sensors— specially designed polymer matrices or surface-enhanced glasses/films with grafted or absorbed photometric reagents [1]. The examples that will be given include trace metal determination, classical and enzyme kinetic indicator systems for phenolic compounds, immunoassays, and nanoparticle-assisted sensible materials. Finally, some schematics under discussion involve differential and wide-beam schemes and those combining several photothermal methods (with laser and non-laser excitation sources), fluorescence, scattering, photoacoustics, etc., relevant for analytical practice (aerosol analysis, table-top analytical instruments, etc.) will be discussed. The possibilities of photoacoustic spectroscopy for the chemical analysis of highly concentrated samples as ‘scattering-proof’ high-accuracy technique for the determination and estimation of physicochemical parameters will be discussed and exemplified.