Hydrogen-bonding-driven spontaneous gelation of water-soluble phospholipid polymers in aqueous medium

Abstract

It has been found that mixing of two kinds of water-soluble phospholipids polymers, such as poly(2-methacryloyloxyethyl phosphorylcholine-co-methacrylic acid) (PMA) and poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB), spontaneously forms a hydrogel in aqueous medium at room temperature without any chemical treatment. However, the mechanism of spontaneous gelation has not been clarified yet. The purpose of this study is to investigate the gelation mechanism of the hydrogel. Moreover, effects of ions on gelation and dissolution behavior were observed. We investigated the mechanism of the hydrogel formation by spectroscopic techniques and a rheological method with attention to the interactions between polymer chains. Both Raman spectroscopic analysis and FT-IR analysis revealed that carboxyl groups in methacrylic acid (MA) formed dimer when two polymer solutions were mixed, and the results of the rheological study showed dissociation of carboxyl groups caused dissolution of the hydrogel. Thus, the gelation occurred due to the formation of dimers by hydrogen bonding which acts as a physical cross-linking of polymer chains. The hydrogel dissolved in a large amount of aqueous medium. We also observed the addition of inorganic salts during the preparation of the hydrogel affected the gelation and dissolution behaviors by a rheological and a weight measuring method, respectively. The gelation period became longer in the presence of NaCl and CaCl2 compared with that in the absence of these salts. NaCl and CaCl2 disturbed the formation of hydrogen bonding between carboxyl groups by stabilization of carboxylate anion of the MA units. On the other hand, addition of FeCl3 made the gelation period shorter and stabilized the hydrogel in the aqueous medium. This is because FeCl3 can suppress dissociation of the carboxyl groups by acidic condition of FeCl3 aqueous solution and cross-link the carboxylate anions in the PMA effectively.

The prevention of peritendinous adhesions by a phospholipid polymer hydrogel formed in situ by spontaneous intermolecular interactions

“…These properties are based on effective suppression of protein adsorption at the MPC polymer surface. We have therefore prepared a hydrogel by mixing aqueous solutions of two MPC polymers, poly[MPC-co-methacrylic acid(MA)] (PMA) and poly[MPC-co-n-butyl methacrylate(BMA)] (PMB), at room temperature without any chemical treatment [21,22]. The PMA/ PMB hydrogel is formed by molecular interactions such as hydrogen bonding and hydrophobic interactions, and it is expected to be promising for in situ setting because of its excellent biocompatibility and dissociation ability.…”

Temporal and spatially controllable cell encapsulation using a water-soluble phospholipid polymer with phenylboronic acid moiety

“…Also, the MPC polymer hydrogel membranes have a high gas permeability [8] and solute permeability [9]. We succeeded in the spontaneously gelation of water-soluble MPC polymers from their aqueous solutions by hydrogen bonding without any physical treatments [10][11][12][13]. The MPC polymer hydrogel prepared from an aqueous solution containing 5 wt% poly[MPC-co-n-butyl methacrylate (BMA)] and poly(MPC-co-methacrylic acid) could be dissociated by a change in pH.…”

Cytocompatible and spontaneously forming phospholipid polymer hydrogels

“…Synthetic and purification methods to produce massive amounts of MPC have been established by Ishihara [27,28], taking advantage of this material in a wide range of biomedical applications, such as surface modification of long-term implantable artificial organs [29][30][31][32]. The mixing of two aqueous MPC polymer solutions induced the spontaneous formation of a hydrogel in aqueous medium at room temperature via hydrogen bonding without any chemical treatment [33][34][35][36].…”