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

Abstract

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.

In vitro and in vivo drug release and antibacterial properties of the novel vancomycin-loaded bone-like hydroxyapatite/poly amino acid scaffold

“…By adjusting the proportion of BHA and PAA, the rate and speed of its degradation can be adjusted, suggesting that the scaffold has great potential as a bone repair and drug carrier. 6 Our previous research verified that the biostructure of this scaffold was very similar to human bone in terms of its porosity and biodegradability, further supporting its potential as an ideal drug delivery carrier. Vancomycin-loaded BHA/PAA (V-BHA/ PAA) bony scaffold was successfully fabricated using a homogeneous diffusion control system.…”

Nitinol Modified by In Situ Generated Diazonium from Its Nitro Precursor for the SI-ATRP of 2-Hydroxyethyl Methacrylate

“…First, the conditions used contribute to an hydrothermal-like treatment which reinforces the TiO 2 layer of NiTi as well as its biocompatibility but also its corrosion resistance. 4,[9][10][11][12] Second, it contributes the formation of a biocompatible 76 and bioactive [34][35][36]77 film of PHEMA which improves also the corrosion resistance.…”

“…This SI-ATRP initiator leads to the successful polymerization of HEMA grafted at the surface of NiTi. The bioactivity of the PHEMA layer could be used for cardiovascular 77 and orthopedic [34][35][36] applications areas, the main application fields of NiTi. Furthermore, the ATRP polymerization of HEMA has a double effect on the corrosion resistance of the modified NiTi.…”

Effectiveness of non-biodegradable poly(2-hydroxyethyl methacrylate)-based hydrogel particles as a fibroblast growth factor-2 releasing carrier

“…However, homo-polymers made of HEMA easily aggregate and are difficult to apply to dental resins. In addition, previously reported polymer combinations such as HEMA and gelatin [22], hydroxyapatite [23], and polycaprolactone [24] are degradable. Kitagawa et al [9] developed a novel hydrogel consisting of polyme- 12 h and 1, 2, 3, 4, 5, 7, 10, and 14 days (n = 4).…”