A novel study of pH-dependent optical properties of a water-soluble PNPG-PEG as a conjugated polymer nanoparticle to easy detection of dopamine: Applying MCR-ALS method

This report is the first study on the coupling of UV-visible and fluorescence spectroscopic data from protein interacted with polyethylene glycol-functionalized poly (N-phenyl glycine) (PNPG-PEG) polymer in different pH values, applying multivariate curve resolution-alternative least-squares (MCR-ALS) algorithm. The obtained nanoparticles (BSA+PNPG-PEG NPs) are useful for sensitive dopamine (DA) detection at optimized pH value. Fabrication of conductive polymer nanoparticle (PNPG), using a two-step polymerization process, was followed by functionalization using PEG. Several characterization methods including XPS, SEM, TGA, FTIR, DLS, UV-vis absorption, and fluorescence spectroscopy confirmed the successful formation of PNPG-PEG NPs [1]. The polymer NPs were then combined with BSA (BSA+PNPG-PEG NPs, (complex I)) to produce a pH-sensitive complex, for presenting an easy, simple, and economical strategy to determine dopamine. Under the various range of pH (2.0, 8.0, and 10.0), in the first step, we applied of DA+ PNPG-PEG (complex II) for directly detect DA in aqua solation, but it does not obviously result. Then we applied of complex I the addition of dopamine to cause the complexed chemical system of DA+BSA+PNPG-PEG (mixture complex III). In pH value of 10.0 compared to the acidic and natural reaction matrix, it was found that the introduction of dopamine solution led to a remarkable increment of the emission intensity in complex III. To benefit from MCR-ALS, rotational ambiguities were reduced using non-negativity, selectivity, and equality constraints. MCR-ALS successfully resolved meaningful pure spectral and concentration profiles [2]. MCR-ALS technique resolved the bilinear data matrix and their resolved spectral and concentration profiles were applied to study DA in complex system (PNPGPEG+BSA+DA (complex III)) at room temperature. According to the obtained percentage of explained variance (Expl var%) and LOF of the MCR-ALS method, the three meaningful chemical components were obtained for in the complex data (III) from the application of different pH values of 2.0, 8.0, and 10.0 on considered systems of UV-vis and fluorescence spectrum. In other words, the MCR-ALS methodology as an available statical method without any complex separation instruments, the simple, rapid, easy route can provide useful chemical information from overlapping spectrochemical peaks [3, 4].