Poly(ethylene oxide)-based block copolymers with very high molecular weights for biomimetic calcium phosphate mineralization

Abstract

The present article is among the first reports on the effects of poly(ampholyte)s and poly(betaine)s on the biomimetic formation of calcium phosphate. We have synthesized a series of di-and triblock copolymers based on a non-ionic poly(ethylene oxide) block and several charged methacrylate monomers, 2-(trimethylammonium)ethyl methacrylate chloride, 2-((3-cyanopropyl)-dimethylammonium)ethyl methacrylate chloride, 3-sulfopropyl methacrylate potassium salt, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide. The resulting copolymers are either positively charged, ampholytic, or betaine block copolymers. All the polymers have very high molecular weights of over 10 6 g mol À1 . All polymers are water-soluble and show a strong effect on the precipitation and dissolution of calcium phosphate.The strongest effects are observed with triblock copolymers based on a large poly(ethylene oxide) middle block (nominal M n ¼ 100 000 g mol À1 ). Surprisingly, the data show that there is a need for positive charges in the polymers to exert tight control over mineralization and dissolution, but that the exact position of the charge in the polymer is of minor importance for both calcium phosphate precipitation and dissolution.

Anionic Polymer Brushes for Biomimetic Calcium Phosphate Mineralization—A Surface with Application Potential in Biomaterials

“…Note that XPS experiments do not detect copper signals from the polymerization reaction. This is consistent with previous data [15,18] showing that the CuCl catalyst is removed to below the detection limit of the XPS.…”

“…All polymer brushes Brush1, Brush2, Brush3 were synthesized with the same strategy using an established protocol [15,18]. A 5 mL screw lid vial was cleaned with concentrated nitric acid (69%) and ultrapure water just before use.…”

“…Mineralization of the brushes was achieved using an identical approach for all samples Min1, Min2, and Min3 [15,18]. In brief, for mineralization, 15 mL of the Ca-containing component of doubly concentrated simulated body fluid (Ca-2SBF) and 15 mL of the phosphate component of doubly concentrated SBF (P-2SBF) were mixed and stirred.…”

Effect of the aggregation state of amorphous calcium phosphate on hydroxyapatite nucleation kinetics

“…Polyelectrolytes are known to be used to obtain well dispersed ACPs, 18,19 but water-soluble polyelectrolytes have a strong effect on the precipitation and dissolution of calcium phosphate. 20,21 In previous work, we found that the soluble polymers (non-collagenous) inhibit HAP nucleation by absorbed on ACP surface, thus decrease the surface area of ACP reacting with Ca 2+ . 17 However, in this work, we used assembled collagen-I brils (insoluble in our system) to control the aggregation of ACPs, thus increase the surface area of ACP directly.…”

Biological properties of calcium phosphate biomaterials for bone repair: a review

“…Generally, CaP coating is incorporated with polymer via coating on the polymer surface or mixing these two ingredients and then shaping using desired scaffolds. Coated composites are usually prepared by electrochemically assisted co-deposition 154 or two-step biomimetic methods; 155,156 the mixed composites are fabricated via the 3D printing technique, 157 extrusion or direct injection into the bone defect site. Interestingly, the CaP-coated polymer nanober was recently fabricated by Junginger et al 158 via the mineralization process, and it is thought to add value to the synthesis of advanced hybrid materials for bone repair.…”