Behavior of hybrid thermosensitive nanosystem dextran-graft-PNIPAM/gold nanoparticles: characterization within LCTS
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Thermally responsive polymers based on poly (N-isopropylacrylamide) (PNIPAM) with lower critical solution temperature (LCST) in the region of physiological temperatures become a subject of a study as promising material for biomedical application. In the present work, the star-like dextran-graft-PNIPAM with incorporated gold nanoparticles (AuNPs) in water suspension were studied by quasi-elastic light scattering (QELS), transmission electron microscopy (TEM), and spectroscopic methods in the temperature range around LCST. The analysis of QELS results revealed the individual polymer macromolecules with incorporated inside AuNPs and their aggregates, which demonstrate the LCST near 34 °C with the collapse of individual macromolecules and polymer aggregates too. The absorption spectroscopy measurements showed that the polymer structure is reversible at LCST and heating of polymer/AuNP nanosystems from room temperatures to LCTS does not accompany with a release of AuNPs from the polymer matrix. Raman spectra of nanohybrids were measured below and above LCTS and analyzed in details by employing DFT calculations. Two intense bands in the region 50–300-cm−1 region were observed for the first time. They were assigned to the stretching vibrations of Au-Au and Au-O (NIPAM) bonds. The presented work shows that the synthesized polymer with AuNPs has high stability going through LCST encouraging their use as a perspective system for drug delivery strategy.
KeywordsPNIPAM Thermoresponsive polymer Gold nanoparticles Surface plasmon resonance Quasi-elastic light scattering Raman spectroscopy DFT calculation Colloids Biomedical applications
A.G. would like to thank to Dr. I. Voloshin for the fruitful discussions. Authors thank to Dr. M. Rawiso and C. Blank from Institute Charles Sadron (Strasbourg, France) for the SEC and TEM characterization of polymer sample.
Publications are based on the research provided by the grant support of the State Fund For Fundamental Research (project Ф76/64-2017 “New multifunctional hybrid nanocomposites for photodynamic chemotherapy of tumor cells”). This work has been partially supported by National Academy of Sciences of Ukraine (Grant No. 15/18-H within the program “Fundamental Problems of the creation of new Nanomaterials and Nanotechnology” and Grant No. 0114U001070).
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Conflict of interest
The authors declare that they have no conflict of interest.
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