Characterization of Hydration Water Bound to Choline Phosphate-Containing Polymers

Abstract

Zwitterionic methacrylate polymers with either choline phosphate (CP) (poly(MCP)) or phosphorylcholine (PC) (poly(MPC)) side groups were analyzed to characterize the bound hydration water molecules as nonfreezing water (NFW), intermediate water (IW), or free water (FW). This characterization was carried out by differential scanning calorimetry (DSC) of polymer/water systems, and the enthalpy changes of cold crystallization and melting were determined. The electron pair orientation of CP is opposite to that of PC, and the former binds the alkyl terminal groups at the phosphate esters. The numbers of NFW and IW molecules per monomer unit of poly(MCP) with an isopropyl terminal group were estimated to be 10.7 and 11.3 mol/mol, respectively, which were slightly greater than those of the poly(MCP) bearing an ethyl terminal group. More NFW and IW molecules hydrated the phosphobetaine polyzwitterions, poly(MCP) and poly(MPC), compared with carboxybetaine and sulfobetaine polymers. Moreover, the hydration states of polyelectrolytes were compared with the zwitterionic polymers. Finally, we discuss the relationship between the amount of hydration water and bio-inert properties.

Phase Behavior of Double Zwitterionic Block Copolymers in Water: Morphology Transition through Concentration Dependent Selectivity of Water Partitioning

“…Since the local hydration efficiency of the charges in the zwitterions is independent on the zwitterion species, water is involved in each phase at the high concentration stage. [ 34 ] However, once the water content is above the water capacity of the PSB4 phase, water is subjected to partition selectively to the PCB2 phase. The concentration‐dependent selectivity of water partitioning in the self‐assembly of double hydrophilic block copolymers is unique and could be specific to zwitterionic block copolymers.…”

A Perspective of Engineered Lipids and Liposomes: Chemical Design and Functional Application Based on Therapeutic Safety

“…73 The variance in conformation between the atoms centered on phosphorus in PC lipid headgroup and the atoms centered on nitrogen in CP lipid headgroup results in differences in the spatial rotation degrees and entropy change (ΔS) of the headgroups. 74 Kobayashi et al showed that phosphoric acid groups had stronger hydrogen bond associations with water molecules. Thus, each CP headgroup in poly(2-methacryloyloxyethyl choline phosphate) (PMCP) could tightly bind 11 water molecules.…”

“…In comparison, each PC headgroup in poly(2methacryloyloxyethyl phosphorylcholine) (PMPC) binds 9 water molecules, indicating that CP liposomes could form a tighter and thicker hydration layer than PC liposomes. 74 Attributing to the increased thickness of the hydration layer, CP liposomes exhibit better antiprotein adsorption and antibacterial property than PC liposomes. 71 In addition, the maximum drug loading content of CP liposomes could reach 17.6%, 71 and the minimum particle size of drug unloaded CP liposomes could reach 30 nm, which may be related to the conformation of the CP headgroup and the compact hydration layer.…”

Design of biomaterials through direct ring-opening metathesis polymerisation of functionalised cyclic alkenes

“…94 The hydration state and biocompatibility of these polymers can be tuned by controlling the side chain spacing 94,114,139–141 and changing the chemical structure of the side chains. 142–167…”