Mechanical and cytotoxicity testing of acrylic bone cement embedded with microencapsulated 2-octyl cyanoacrylate

Abstract

The water-reactive tissue adhesive 2-octyl cyanoacrylate (OCA) was microencapsulated in polyurethane shells and incorporated into Palacos R bone cement. The tensile and compressive properties of the composite material were investigated in accordance with commercial standards, and fracture toughness of the capsule-embedded bone cement was measured using the tapered double-cantilever beam geometry. Viability and proliferation of MG63 human osteosarcoma cells after culture with extracts from Palacos R bone cement, capsule-embedded Palacos R bone cement, and OCA were also analyzed. Incorporating up to 5 wt % capsules had little effect on the compressive and tensile properties of the composite, but greater than 5 wt % capsules reduced these values below commercial standards. Fracture toughness was increased by 13% through the incorporation of 3 wt % capsules and eventually decreased below the toughness of the capsule-free controls at capsule contents of 15 wt % and higher. The effect on cell proliferation and viability in response to extracts prepared from capsule-embedded and commercial bone cements were not significantly different from each other, whereas extracts from OCA were moderately toxic to cells. Overall, the addition of lower wt % of OCA-containing microcapsules to commercial bone cement was found to moderately increase static mechanical properties without increasing the toxicity of the material.

Keywords: biomaterial; bone cement; cytotoxicity; mechanical properties; self-healing.

FIGURE 1

PMMA samples for (A) tension, (B) compression, and (C) fracture toughness testing. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

FIGURE 2

Relationship between capsule content and (A) ultimate tensile strength and (B) Young’s modulus (average ± SEM, n = 5).

FIGURE 3

(A) Relationship between capsule content and the ultimate compressive strength of bone cement (average ± SEM, n = 3 with five replicates per group). Photographs of samples containing (B) 0 wt % and (C) 40 wt % capsules postcompression testing. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

FIGURE 4

Load with increasing vertical displacement is shown in (A) for samples containing 0 and 3 wt % capsules. Effect of capsule content on fracture toughness is presented in (B) (average ± SEM, n = 5). Fracture plane roughness and subsurface microcracking are observed in SEM images of the side views of samples containing (C) 0 wt % and (D) 3 wt % capsules. Direction of crack propagation is indicated by arrows.

FIGURE 5

Viability of MG63 human osteosarcoma cells after 72 h exposure to (A) PMMA bone cement and (B) OCA extracts (average ± SEM, n = 4). Coverage by live cells in the positive controls, Cu and Loctite®, was significantly different from all treatment groups, although significance is not indicated on the figures.

FIGURE 6

Proliferation of MG63 human osteosarcoma cells in response to growth in extract from (A, B, C) bone cement and (D, E, F) OCA after (A, D) 24, (B, E) 48, and (C, F) 72 h (average ± SEM, n = 4). Proliferation of cells in the positive controls, Cu and Loctite®, was significantly different from all treatment groups, although significance is not indicated on the figures.