title: Photoactive chitosan switching on bone-like apatite deposition.
abstract: The work was focused on the synthesis and characterization of the chitosan-g-fluorescein (CHFL) conjugate polymer as a biocompatible amphiphilic water-soluble photosensitizer, able to stimulate hydroxyapatite deposition upon visible light irradiation. Fluorescein (FL) grafting to chitosan (CH) chains was confirmed by UV-vis analysis of water solutions of FL and CHFL and by Fourier transform infrared spectroscopy (FTIR-ATR) analysis of CHFL and CH. Smooth CHFL cast films with 4 microm thickness were obtained by solvent casting. Continuous exposure to visible light for 7 days was found to activate the deposition of calcium phosphate crystals from a conventional simulated body fluid (SBF 1.0x) on the surface of CHFL cast films. EDX and FTIR-ATR analyses confirmed the apatite nature of the deposited calcium phosphate crystals. CHFL films preincubated in SBF (1.0x) solution under visible light irradiation and in the dark for 7 days were found to support the in vitro adhesion and proliferation of MG63 osteoblast-like cells (MTT viability test; 1-3 days culture time). On the other hand, the mineralization ability of MG63 osteoblast-like cells was significantly improved on CHFL films preincubated under visible light exposure (alkaline phosphatase activity (ALP) test for 1, 3, 7, and 14 days). The use of photoactive biocompatible conjugate polymer, such as CHFL, may lead to new therapeutic options in the field of bone/dental repair, exploiting the photoexcitation mechanism as a tool for biomineralization.
authors.affiliation: Department of Mechanics, Politecnico di Torino, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Chiono
authors.forename: Piergiorgio
authors.initials: P
authors.lastname: Gentile
authors.forename: Francesca
authors.initials: F
authors.lastname: Boccafoschi
authors.forename: Irene
authors.initials: I
authors.lastname: Carmagnola
authors.forename: Momchil
authors.initials: M
authors.lastname: Ninov
authors.forename: Ventsislava
authors.initials: V
authors.lastname: Georgieva
authors.forename: George
authors.initials: G
authors.lastname: Georgiev
authors.forename: Gianluca
authors.initials: G
authors.lastname: Ciardelli
mesh_terms: D018786:Bone Substitutes / Q000737:chemistry* / Q000528:radiation effects; D002113:Calcification, Physiologic / Q000502:physiology / Q000528:radiation effects; D002478:Cells, Cultured; D048271:Chitosan / Q000737:chemistry* / Q000528:radiation effects; D019793:Fluorescein / Q000737:chemistry / Q000528:radiation effects; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D010006:Osteoblasts / Q000378:metabolism / Q000528:radiation effects; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D018786:Bone Substitutes; D006882:Hydroxyapatites; D017319:Photosensitizing Agents; D048271:Chitosan; D019793:Fluorescein