title: Effects of oxygen plasma treatment on interfacial shear strength and post-peak residual strength of a PLGA fiber-reinforced brushite cement.
abstract: Biodegradable calcium phosphate cements (CPCs) are promising materials for minimally invasive treatment of bone defects. However, CPCs have low mechanical strength and fracture toughness. One approach to overcome these limitations is the modification of the CPC with reinforcing fibers. The matrix-fiber interfacial shear strength (ISS) is pivotal for the biomechanical properties of fiber-reinforced CPCs. The aim of the current study was to control the ISS between a brushite-forming CPC and degradable PLGA fibers by oxygen plasma treatment and to analyze the impact of the ISS alterations on its bulk mechanical properties. The ISS between CPC matrix and PLGA fibers, tested in a single-fiber pull-out test, increased up to 2.3-fold to max. 3.22±0.92MPa after fiber oxygen plasma treatment (100-300W, 1-10min), likely due to altered surface chemistry and morphology of the fibers. This ISS increase led to more efficient crack bridging and a subsequent increase of the post-peak residual strength at biomechanically relevant, moderate strains (up to 1%). At the same time, the work of fracture significantly decreased, possibly due to an increased proportion of fractured fibers unable to further absorb energy by frictional sliding. Flexural strength and flexural modulus were not affected by the oxygen plasma treatment. This study shows for the first time that the matrix-fiber ISS and some of the resulting mechanical properties of fiber-reinforced CPCs can be improved by chemical modifications such as oxygen plasma treatment, generating the possibility of avoiding catastrophic failures at the implant site and thus enhancing the applicability of biodegradable CPCs for the treatment of (load-bearing) bone defects.
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany; Jena School for Microbial Communication (JSMC), Friedrich Schiller University Jena, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Maenz
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Hennig
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Mühlstädt
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle", Eisenberg, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Kunisch
authors.affiliation: Chair of Orthopedics, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle", Eisenberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Bungartz
authors.affiliation: Chair of Orthopedics, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle", Eisenberg, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Brinkmann
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Bossert
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle", Eisenberg, Germany.
authors.forename: Raimund W
authors.initials: RW
authors.lastname: Kinne
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Germany; Jena School for Microbial Communication (JSMC), Friedrich Schiller University Jena, Germany. Electronic address: k.jandt@uni-jena.de.
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Jandt
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D010100:Oxygen / Q000737:chemistry*; D058626:Plasma Gases / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D002130:Calcium Phosphates; D058626:Plasma Gases; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C494366:calcium phosphate, dibasic, dihydrate; D010100:Oxygen
keywords: Calcium phosphate cement; Fiber reinforcement; Interfacial shear strength; Mechanical properties; Plasma treatment