title: Thermoresponsive Polymers for Nuclear Medicine: Which Polymer Is the Best?
abstract: Thermoresponsive polymers showing cloud point temperatures (CPT) in aqueous solutions are very promising for the construction of various systems in biomedical field. In many of these applications these polymers get in contact with ionizing radiation, e.g., if they are used as carriers for radiopharmaceuticals or during radiation sterilization. Despite this fact, radiosensitivity of these polymers is largely overlooked to date. In this work, we describe the effect of electron beam ionizing radiation on the physicochemical and phase separation properties of selected thermoresponsive polymers with CPT between room and body temperature. Stability of the polymers to radiation (doses 0-20 kGy) in aqueous solutions increased in the order poly(N-vinylcaprolactam) (PVCL, the least stable) ≪ poly[N-(2,2-difluoroethyl)acrylamide] (DFP) < poly(N-isopropylacrylamide) (PNIPAM) ≪ poly(2-isopropyl-2-oxazoline-co-2-n-butyl-2-oxazoline) (POX). Even low doses of β radiation (1 kGy), which are highly relevant to the storage of polymer radiotherapeutics and sterilization of biomedical systems, cause significant increase in molecular weight due to cross-linking (except for POX, where this effect is weak). In the case of PVCL irradiated with low doses, the increase in molecular weight induced an increase in the CPT of the polymer. For PNIPAM and DFP, there is strong chain hydrophilization leading to an increase in CPT. From this perspective, POX is the most suitable polymer for the construction of delivery systems that experience exposure to radiation, while PVCL is the least suitable and PNIPAM and DFP are suitable only for low radiation demands.
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Ondřej
authors.initials: O
authors.lastname: Sedláček
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Peter
authors.initials: P
authors.lastname: Černoch
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Kučka
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Rafał
authors.initials: R
authors.lastname: Konefal
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Štěpánek
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Vetrík
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Lodge
authors.affiliation: Institute of Macromolecular Chemistry, v.v.i., Academy of Sciences of the Czech Republic , Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Hrubý
mesh_terms: D000180:Acrylic Resins; D008970:Molecular Weight; D009683:Nuclear Medicine; D011108:Polymers / Q000032:analysis*; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D011108:Polymers