Microencapsulation of 2‐octylcyanoacrylate tissue adhesive for self‐healing acrylic bone cement

Abstract

Here, we report the first phase of developing self-healing acrylic bone cement: the preparation and characterization of polyurethane (PUR) microcapsules containing a medical cyanoacrylate tissue adhesive. Capsules were prepared by interfacial polymerization of a toluene-2,4-diisocyanate-based polyurethane prepolymer with 1,4-butanediol to encapsulate 2-octylcyanoacrylate (OCA). Various capsule characteristics, including: resultant morphology, average size and size distribution, shell thickness, content and reactivity of encapsulated agent, and shelf life are investigated and their reliance on solvent type and amount, surfactant type and amount, temperature, pH, agitation rate, reaction time, and mode of addition of the oil phase to the aqueous phase are presented. Capsules had average diameters ranging from 74 to 222 μm and average shell thicknesses ranging from 1.5 to 6 μm. The capsule content was determined via thermogravimetric analysis and subsequent analysis of the capsules following up to 8 weeks storage revealed minimal loss of core contents. Mechanical testing of OCA-containing capsules showed individual capsules withstood compressive forces up to a few tenths of Newtons, and the contents released from crushed capsules generated tensile adhesive forces of a few Newtons. Capsules were successfully mixed into the poly(- methyl methacrylate) bone cement, surviving the mixing process, exposure to methyl methacrylate monomer, and the resulting exothermic matrix curing.

Self-healing polymeric materials based on microencapsulated healing agents: From design to preparation

“…14 toluene-2,4-diisocyanate (TDI)-based PU prepolymer and 1,4-butanediol to encapsulate 2-octylcyanoacrylate (OCA) [104]. The produced microcapsules prepared at agitation rates of 350-1100 rpm had an average diameter ranging from approximately 75 μm to 220 μm.…”

Microcapsule-based self-healing materials

“…Brochu et al [27] reported polyurethane (PU) walled microcapsules containing medical cyanoacrylate tissue adhesive for developing self-healing acrylic bone cement. The microcapsules were prepared by interfacial polymerization of toluene-2,4-diisocyanate (TDI)-based PU prepolymer with 1,4-butanediol (BD) to encapsulate 2-octylcyanoacrylate (OCA).…”

Extended fatigue life of a catalyst free self‐healing acrylic bone cement using microencapsulated 2‐octyl cyanoacrylate

“…This approach somewhat mimics a network of blood vessels responsible for healing of damaged tissue [2]. The team of White, Sottos and Moore has reported extensively on a similar strategy where liquid monomer is contained in microcapsules that are distributed at 5-10wt% in polymer matrix [3-10]. Again, capsule rupture by a propagating crack releases monomer into the crack plane where the monomer is exposed to co-embedded catalyst, cures, and heals the crack.…”

“…For these reasons, PMMA bone cement was an attractive option for the first self-healing biomaterial designed using the matrix repolymerization scheme [9, 12]. Our scheme is to encapsulate the water-reactive healing agent 2-octyl cyanoacrylate (OCA) tissue adhesive, commercially-known as Dermabond™, in polyurethane (PUR) microcapsules, and then disperse the capsules in a matrix of Palacos R PMMA bone cement [10]. This creates a catalyst-free self-healing bone cement system is based on the matrix repolymerization scheme (Figure 1).…”

“…We recently reported the successful encapsulation of OCA in PUR microspheres and its incorporation into a Palacos R bone cement matrix [10]. Subsequently we characterized the tension, compression, fracture toughness, and cytotoxicity of the bone cement embedded with OCA-containing microcapsules using ASTM and ISO standards [13].…”