Adhesive Cements That Bond Soft Tissue Ex Vivo

Abstract

The aim of the present study was to evaluate the soft tissue bond strength of a newly developed, monomeric, biomimetic, tissue adhesive called phosphoserine modified cement (PMC). Two types of PMCs were evaluated using lap shear strength (LSS) testing, on porcine skin: a calcium metasilicate (CS1), and alpha tricalcium phosphate (αTCP) PMC. CS1 PCM bonded strongly to skin, reaching a peak LSS of 84, 132, and 154 KPa after curing for 0.5, 1.5, and 4 h, respectively. Cyanoacrylate and fibrin glues reached an LSS of 207 kPa and 33 kPa, respectively. αTCP PMCs reached a final LSS of ≈110 kPa. In soft tissues, stronger bond strengths were obtained with αTCP PMCs containing large amounts of amino acid (70–90 mol%), in contrast to prior studies in calcified tissues (30–50 mol%). When αTCP particle size was reduced by wet milling, and for CS1 PMCs, the strongest bonding was obtained with mole ratios of 30–50% phosphoserine. While PM-CPCs behave like stiff ceramics after setting, they bond to soft tissues, and warrant further investigation as tissue adhesives, particularly at the interface between hard and soft tissues.

Factors That Determine the Adhesive Strength in a Bioinspired Bone Tissue Adhesive

“…The average particle size and composition of synthesized αTCP is shown in Table 2. The average particle size and purity were comparable to materials used in prior PMC studies [9].…”

“…O-phospho-L-serine (phosphoserine) was purchased from Flamma SpA (>95%, Flamma SpA, Bergamo, Italy). Alpha tricalcium phosphate (αTCP, Ca3(PO4)2) was synthesized as described previously [9,10]. Palacos, a clinical poly-methyl methacrylate (PMMA) was obtained from Heraeus Kulzer (Medical GmbH, Hanau, Germany).…”

“…(A) Different curing environments (phosphate-buffered saline (PBS), water, or 100% humidity) and grip duration (24 h, blue box; or 5 min, red box) before curing did not affect the adhesive strength of 27% PMC (from left to right: groups #1, 4, 2, 5, 3, 6). (B) When the grip duration was shortened and the grip force reduced to mimic clinical conditions, comparable adhesive strength was observed in all samples except the automated mixing sample (red border) and low grip force (3 N) samples gripped for 5 min (from left to right: groups #3, 9,6,10,7,11,8,12,33,34; the red border indicates high speed mixing; green border indicates bone samples). (C) Different mole ratios of phosphoserine to αTCP, and cure conditions, affected adhesive strengths (from left to right: groups #3, 14, 15; 19-21; 13, 16-18) (100% humidity samples were gripped for 1 min).…”

“…The powders used for making PMC samples have been previously characterized [9,10]. Alpha tricalcium phosphate (αTCP,) powder was synthesized as previously described.…”

“…Coacervation and nanoscale electrostatic interactions are also sufficient to create relatively strong tissue adhesion [4][5][6][7]. Recently, strong adhesion has been created in biomaterials that are not adhesive (bioceramics) by incorporating a modified amino acid (phosphoserine) [8][9][10]. Phosphoserine-modified cements (PMCs) display a unique microstructure, appearing amorphous rather than crystalline [10], can stabilize bioactive phases and remodel into precursors of hydroxyapatite [11], and display significantly improved healing, compared to unmodified cements [12][13][14][15].…”