title: A comparative study of the effects of different bioactive fillers in PLGA matrix composites and their suitability as bone substitute materials: A thermo-mechanical and in vitro investigation.
abstract: Bone substitute composite materials with poly(L-lactide-co-glycolide) (PLGA) matrices and four different bioactive fillers: CaCO3, hydroxyapatite (HA), 45S5 Bioglass(®) (45S5 BG), and ICIE4 bioactive glass (a lower sodium glass than 45S5 BG) were produced via melt blending, extrusion and moulding. The viscoelastic, mechanical and thermal properties, and the molecular weight of the matrix were measured. Thermogravimetric analysis evaluated the effect of filler composition on the thermal degradation of the matrix. Bioactive glasses caused premature degradation of the matrix during processing, whereas CaCO3 or HA did not. All composites, except those with 45S5 BG, had similar mechanical strength and were stiffer than PLGA alone in compression, whilst all had a lower tensile strength. Dynamic mechanical analysis demonstrated an increased storage modulus (E') in the composites (other than the 45S5 BG filled PLGA). The effect of water uptake and early degradation was investigated by short-term in vitro aging in simulated body fluid, which indicated enhanced water uptake over the neat polymer; bioactive glass had the greatest water uptake, causing matrix plasticization. These results enable a direct comparison between bioactive filler type in poly(α-hydroxyester) composites, and have implications when selecting a composite material for eventual application in bone substitution.
authors.affiliation: Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: R L
authors.initials: RL
authors.lastname: Simpson
authors.affiliation: Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada.
authors.forename: S N
authors.initials: SN
authors.lastname: Nazhat
authors.affiliation: Materials Science Centre, School of Materials, University of Manchester, Grovesnor Street, Manchester M1 7HS, UK. Electronic address: jonny.blaker@manchester.ac.uk.
authors.forename: J J
authors.initials: JJ
authors.lastname: Blaker
authors.affiliation: Department of Chemical Engineering, Polymer and Composite Engineering (PaCE) Group, Imperial College London, London SW7 2AZ, UK.
authors.forename: A
authors.initials: A
authors.lastname: Bismarck
authors.affiliation: Institute of Dentistry, Dental Physical Science Unit, Queen Mary, University of London, London E1 4NS, UK.
authors.forename: R
authors.initials: R
authors.lastname: Hill
authors.affiliation: Department of Materials, Imperial College London, London SW7 2BP, UK; Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremburg, 91058 Erlangen, Germany. Electronic address: aldo.boccaccini@ww.uni-erlangen.de.
authors.forename: A R
authors.initials: AR
authors.lastname: Boccaccini
authors.affiliation: Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: U N
authors.initials: UN
authors.lastname: Hansen
authors.affiliation: Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK; Musculoskeletal Surgery Group, Imperial College School of Medicine, London W6 8RF, UK.
authors.forename: A A
authors.initials: AA
authors.lastname: Amis
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry; D001826:Body Fluids; D018786:Bone Substitutes / Q000737:chemistry*; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D055595:Mechanical Phenomena; D008970:Molecular Weight; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D013696:Temperature; D013997:Time Factors
chemical_list: D018786:Bone Substitutes; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid
keywords: Bioactive glass; Bone substitute; Composite; Hydroxyapatite; Poly(α-hydroxyester)