title: Enzymatic mineralization of gellan gum hydrogel for bone tissue-engineering applications and its enhancement by polydopamine.
abstract: Interest is growing in the use of hydrogels as bone tissue-engineering (TE) scaffolds due to advantages such as injectability and ease of incorporation of active substances such as enzymes. Hydrogels consisting of gellan gum (GG), an inexpensive calcium-crosslinkable polysaccharide, have been applied in cartilage TE. To improve GG suitability as a material for bone TE, alkaline phosphatase (ALP), an enzyme involved in mineralization of bone by cleaving phosphate from organic phosphate, was incorporated into GG hydrogels to induce mineralization with calcium phosphate (CaP). Incorporated ALP induced formation of apatite-like material on the submicron scale within GG gels, as shown by FTIR, SEM, EDS, XRD, ICP-OES, TGA and von Kossa staining. Increasing ALP concentration increased amounts of CaP as well as stiffness. Mineralized GG was able to withstand sterilization by autoclaving, although stiffness decreased. In addition, mineralizability and stiffness of GG was enhanced by the incorporation of polydopamine (PDA). Furthermore, mineralization of GG led to enhanced attachment and vitality of cells in vitro while cytocompatibility of the mineralized gels was comparable to one of the most commonly used bone substitute materials. The results proved that ALP-mediated enzymatic mineralization of GG could be enhanced by functionalization with PDA.
authors.affiliation: Department of Biomaterials, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500, HB, Nijmegen, The Netherlands; Polymer Chemistry and Biomaterials (PBM) Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4, 9000, Ghent, Belgium.
authors.forename: T E L
authors.initials: TE
authors.lastname: Douglas
authors.forename: M
authors.initials: M
authors.lastname: Wlodarczyk
authors.forename: E
authors.initials: E
authors.lastname: Pamula
authors.forename: H A
authors.initials: HA
authors.lastname: Declercq
authors.forename: E L W
authors.initials: EL
authors.lastname: de Mulder
authors.forename: M M
authors.initials: MM
authors.lastname: Bucko
authors.forename: L
authors.initials: L
authors.lastname: Balcaen
authors.forename: F
authors.initials: F
authors.lastname: Vanhaecke
authors.forename: R
authors.initials: R
authors.lastname: Cornelissen
authors.forename: P
authors.initials: P
authors.lastname: Dubruel
authors.forename: J A
authors.initials: JA
authors.lastname: Jansen
authors.forename: S C G
authors.initials: SC
authors.lastname: Leeuwenburgh
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology*; D002113:Calcification, Physiologic / Q000187:drug effects*; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D055119:Elastic Modulus / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D005612:Freeze Drying; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry / Q000494:pharmacology*; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D011135:Polysaccharides, Bacterial / Q000494:pharmacology*; D013052:Spectrometry, X-Ray Emission; D013054:Spectrophotometry, Atomic; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D007211:Indoles; D011108:Polymers; D011135:Polysaccharides, Bacterial; C568283:polydopamine; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C048288:gellan gum; D000469:Alkaline Phosphatase