Gelatin–alginate novel tissue adhesives and their formulation–strength effects

Interest in tissue adhesives as alternatives for conventional wound-closing applications such as sutures and staples has increased in the last few decades due to numerous possible advantages, including less discomfort and lower cost. Novel tissue adhesives based on gelatin, with alginate as a polymeric additive and crosslinked by carbodiimide, were recently developed by our research group. The effects of the formulation parameters on the adhesives’ function were investigated in the current study. We examined the effects of gelatin and alginate concentrations and their viscosities on the ability of the bioadhesives to bind soft tissues. The effect of the crosslinking agent’s concentration was studied as well. A qualitative model describing these effects in terms of adherence mechanisms was developed. Our results show that the adherence properties of our new bioadhesives are achieved by a combination of two main mechanisms: mechanical interlocking and chemical adsorption. The former mechanism is probably more dominant. The polymer’s molecular weight and concentration affect the mechanical interlocking through mobility and penetration ability, entanglement of the three-dimensional structure and crosslinking density. The crosslinking agent’s concentration as well as the polymer’s concentration affect the crosslinking density and contribute to higher strength, achieved through both the mechanical interlocking and the chemical adsorption mechanisms. Understanding the effects of the adhesives’ components and their viscosities on the bonding strength enabled us to elucidate the bonding strength mechanisms. This can lead to proper selection of the adhesive formulation and may enable tailoring the bioadhesives to the desired applications.