title: Characterization of polymeric solutions as injectable vehicles for hydroxyapatite microspheres.
abstract: A polymeric solution and a reinforcement phase can work as an injectable material to fill up bone defects. However, the properties of the solution should be suitable to enable the transport of that extra phase. Additionally, the use of biocompatible materials is a requirement for tissue regeneration. Thus, we intended to optimize a biocompatible polymeric solution able to carry hydroxyapatite microspheres into bone defects using an orthopedic injectable device. To achieve that goal, polymers usually regarded as biocompatible were selected, namely sodium carboxymethylcellulose, hydroxypropylmethylcellulose, and Na-alginate (ALG). The rheological properties of the polymeric solutions at different concentrations were assessed by viscosimetry before and after moist heat sterilization. In order to correlate rheological properties with injectability, solutions were tested using an orthopedic device applied for minimal invasive surgeries. Among the three polymers, ALG solutions presented the most suitable properties for our goal and a non-sterile ALG 6% solution was successfully used to perform preliminary injection tests of hydroxyapatite microspheres. Sterile ALG 7.25% solution was found to closely match non-sterile ALG 6% properties and it was selected as the optimal vehicle. Finally, sterile ALG 7.25% physical stability was studied at different temperatures over a 3-month period. It was observed that its rheological properties presented minor changes when stored at 25 degrees C or at 4 degrees C.
authors.affiliation: Dep. de Eng. Mecânica e Gestão Industrial, Escola Superior de Tecnologia e Gestão de Viseu, Campus Politécnico de Repeses, 3504-510, Viseu, Portugal. soliveira@estv.ipv.pt
authors.forename: Serafim M
authors.initials: SM
authors.lastname: Oliveira
authors.forename: Isabel F
authors.initials: IF
authors.lastname: Almeida
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Costa
authors.forename: Cristina C
authors.initials: CC
authors.lastname: Barrias
authors.forename: M Rosa Pena
authors.initials: MR
authors.lastname: Ferreira
authors.forename: M Fernanda
authors.initials: MF
authors.lastname: Bahia
authors.forename: Mário A
authors.initials: MA
authors.lastname: Barbosa
mesh_terms: D001672:Biocompatible Materials / Q000008:administration & dosage / Q000737:chemistry*; D002214:Capsules; D004339:Drug Compounding / Q000379:methods; D017886:Durapatite / Q000008:administration & dosage / Q000737:chemistry*; D005079:Excipients / Q000138:chemical synthesis; D007267:Injections; D014677:Pharmaceutical Vehicles / Q000008:administration & dosage / Q000138:chemical synthesis*; D011108:Polymers / Q000737:chemistry*; D012996:Solutions
chemical_list: D001672:Biocompatible Materials; D002214:Capsules; D005079:Excipients; D014677:Pharmaceutical Vehicles; D011108:Polymers; D012996:Solutions; D017886:Durapatite