Ionizing Radiation Synthesis of Hydrogel Nanoparticles of Gelatin and Polyethylene Glycol at High Temperature

Patricia Y I Takinami; Nelida L Del Mastro; Aiysha Ashfaq; Mohamad Al-Sheikhly

doi:10.3390/polym15204128

Ionizing Radiation Synthesis of Hydrogel Nanoparticles of Gelatin and Polyethylene Glycol at High Temperature

Polymers (Basel). 2023 Oct 18;15(20):4128. doi: 10.3390/polym15204128.

Authors

Patricia Y I Takinami¹, Nelida L Del Mastro¹, Aiysha Ashfaq², Mohamad Al-Sheikhly³

Affiliations

¹ Center of Radiation Technology, Institute of Energy and Radiation Research-IPEN/CNEN, Av. Prof. Lineu Prestes, 2242, Cidade Universitária, Sao Paulo 05508-910, Brazil.
² Department of Chemistry and Biochemistry, University of Maryland College Park, College Park, MD 20742, USA.
³ Department of Materials Science and Engineering, University of Maryland College Park, College Park, MD 20742, USA.

Abstract

Nanohydrogel particles of polyethylene glycol (PEG), gelatin (GEL), and PEG-GEL mixtures (MIXs) were synthesized with a high electron beam and ⁶⁰Co gamma-ray radiation. The relatively novel technique of Asymmetrical Flow Field Flow Fractionation (AF4 or AFFFF) coupled to a Multi-Angle Laser Light Scattering (MALLS) detector was mainly used to determine the hydrodynamic diameter (D_h) of the radiation-synthesized PEG, GEL, and PEG-GEL nanohydrogel particles. Our approach to achieving nanohydrogel particles is to enhance the intracrosslinking reactions and decrease the intercrosslinking reactions of the C-centered radicals of the PEG and GEL. The intracrosslinking reactions of these free radicals were enhanced via irradiation at temperatures of 77-80 °C and using a high dose rate and pulsed irradiation. The shorter average distance between the C-centered free radicals on the backbone of the thermally collapsed PEG and GEL chain, due to the destruction of hydrogen bonds, enhances the intracrosslinking reactions. It was observed that increasing the dose and dose rate decreased the D_h. DLS results lined up with AF4 measurements. This study provides researchers with a clean method to produce GEL-PEG hydrogels without the use of toxic reagents. Particle size can be tuned with dose, dose rate, and temperature as demonstrated in this work. This is ideal for medical applications as the use of ionizing radiation eliminates toxicity concerns and provides simultaneous sterilization of the material.

Keywords: AFFFF; hydrodynamic diameter; inter- and intracrosslinking reactions C-centered radicals; radiation-induced synthesis of nanohydrogels.

Grants and funding

This research received no external funding.