Combinatorial design of hydrolytically degradable, bone-like biocomposites based on PHEMA and hydroxyapatite

• Published in: Polymer (Guilford) 2013-01, Vol.54 (2), p.909-919
• Main Authors: Huang, Jijun, Zhao, Dacheng, Dangaria, Smit J., Luan, Xianghong, Diekwisch, Thomas G.H., Jiang, Guoqing, Saiz, Eduardo, Liu, Gao, Tomsia, Antoni P.
• Format: Article
• Language: English
• Subjects: Applied sciences; biocompatible materials; biocomposites; Biomedical materials; Chains; Combinatorial analysis; Composites; Degradation; drugs; Exact sciences and technology; Forms of application and semi-finished materials; hydrocolloids; Hydrolytic degradation; Hydroxyapatite; Macromer; molecular weight; orthopedics; PHEMA; Polymer industry, paints, wood; polymers; Surgical implants; Technology of polymers; tissue engineering; topography; Weight loss
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2012.12.017

With advantages such as design flexibility in modifying degradation, surface chemistry, and topography, synthetic bone-graft substitutes are increasingly demanded in orthopedic tissue engineering to meet various requirements in the growing numbers of cases of skeletal impairment worldwide. Using a combinatorial approach, we developed a series of biocompatible, hydrolytically degradable, elastomeric, bone-like biocomposites, comprising 60 wt% poly(2-hydroxyethyl methacrylate-co-methacrylic acid), poly(HEMA-co-MA), and 40 wt% bioceramic hydroxyapatite (HA). Hydrolytic degradation of the biocomposites is rendered by a degradable macromer/crosslinker, dimethacrylated poly(lactide-b-ethylene glycol-b-lactide), which first degrades to break up 3-D hydrogel networks, followed by dissolution of linear pHEMA macromolecules and bioceramic particles. Swelling and degradation were examined at Hank's balanced salt solution at 37 °C in a 12-week period of time. The degradation is strongly modulated by altering the concentration of the co-monomer of methacrylic acid and of the macromer, and chain length/molecular weight of the macromer. 95% weight loss in mass is achieved after degradation for 12 weeks in a composition consisting of HEMA/MA/Macromer = 0/60/40, while 90% weight loss is seen after degradation only for 4 weeks in a composition composed of HEMA/MA/Macromer = 27/13/60 using a longer chain macromer. For compositions without a co-monomer, only about 14% is achieved in weight loss after 12-week degradation. These novel biomaterials offer numerous possibilities as drug delivery carriers and bone grafts particularly for low and medium load-bearing applications. [Display omitted]