Protein adsorption and bioactivity of functionalized electrospun membranes for bone regeneration

Abstract

Objectives: To evaluate the adsorption of bone related proteins and bioactivity ofexperimentalfunctionalized (carboxylated oraminated) polymeric membranes for bone regeneration.Methods: Polymethylmethacrylate-based membranes functionalized with carboxyl or aminoradicalswere tested. Membranes were zinc loaded and the adsorption isotherms of zinc were studied. A commercially available polytetrafluoroethylene membrane was used as control. Human plasma proteins, bovine serum albumin, fibrinogen and fibronectin adsorption were measured with a spectrophotometer applying an acid determination protocol. Biomimetic calcium phosphate precipitation on polymeric membraneswas also assessedtroughsimulated body fluid immersion. Scanning electron microscopy and elemental analysis by means of an energy dispersive system were used for mineral deposits identification.Results: Both experimental membranes produced higher protein adsorption than the commercial control that does not adsorb proteins. Carboxylated membranes adsorbed significantly more albumin than the aminated ones, the opposite occurred with fibrinogen. With plasma and fibronectin proteins both type of membranes performed similarly.Only carboxylated membranes were bioactive and precipitated calcium and phosphate on their surfaces. Conclusions: The polymethylmethacrylate zinc-loaded membranesfunctionalized with carboxyl groups performed as highadsorbable membranes forboneregenerationrelated proteins. They also served as templates for mineralization of hydroxyapatite. Clinical significance:Protein adsorption is the initial reaction after the implantation of a biomaterial into the body and will influence subsequent cell function and mineral deposition. Adsorption of those adherent bone related proteins on the implanted material surface could be tightly associated with its ability to induce new bone formation to promote bone regeneration.