title: Gelation behavior of in situ forming gels based on HPMC and biphasic calcium phosphate nanoparticles.
abstract: In this study, in situ forming gels are prepared using biphasic calcium phosphate (BCP) as filler and hydroxypropyl methylcellulose (HPMC) as a matrix exhibiting temperature-sensitive behavior. BCP was composed of β-tricalcium phosphate (β-TCP) with plate-like morphology and nano-sized hyadroxyapatite (HAp). Gel permeation chromatography (GPC) and rheological results showed that low molecular weight HPMC had lower gelation temperature. Effects of BCP content and HAp/β-TCP ratio on rheological behavior of the gels were investigated. According to the results, all samples showed a pseudoplastic behavior and their viscosity increased with increasing mineral phase, especially β-tricalcium phosphate. In order to investigate interaction mechanisms between the mineral phase and polymer and also the effects of ion release, particle size, hydrophobisity, and hydrophilisity, hydrophobic and hydrophilic silica with different particle sizes were also utilized. Results showed that factors affecting the hydrophobisity and hydrophilisity of solution may influence the rheological properties.
authors.affiliation: Iran Polymer and Petrochemical Institute (IPPI) , PO Box 14965/115, Tehran, Iran.
authors.forename: Roghayyeh
authors.initials: R
authors.lastname: Marefat Seyedlar
authors.forename: Azizollah
authors.initials: A
authors.lastname: Nodehi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Atai
authors.forename: Mohammad
authors.initials: M
authors.lastname: Imani
mesh_terms: D002850:Chromatography, Gel; D005782:Gels; D057927:Hydrophobic and Hydrophilic Interactions; D006882:Hydroxyapatites / Q000737:chemistry*; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D012212:Rheology; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
chemical_list: D005782:Gels; D006882:Hydroxyapatites; C074950:hydroxyapatite-beta tricalcium phosphate; D065347:Hypromellose Derivatives; D012822:Silicon Dioxide; D008747:Methylcellulose
keywords: Biphasic calcium phosphate; Calcium phosphates nanoceramics; Hydroxypropyl methylcellulose; Injectable in situ forming gels; Rheological behavior