TY - JOUR
T1 - Enzymatic pH control for biomimetic deposition of calcium phosphate coatings
AU - Nijhuis, Arnold W.G.
AU - Nejadnik, M. Reza
AU - Nudelman, Fabio
AU - Walboomers, X. Frank
AU - te Riet, Joost
AU - Habibovic, Pamela
AU - Tahmasebi Birgani, Zeinab
AU - Yubao, Li
AU - Bomans, Paul H.H.
AU - Jansen, John A.
AU - Sommerdijk, Nico A.J.M.
AU - Leeuwenburgh, Sander C.G.
PY - 2014/10/3
Y1 - 2014/10/3
N2 - The current study has focused on enzymatic decomposition of urea into carbon dioxide and ammonia as a means to increase the pH during biomimetic deposition of Calcium Phospate (CaP) onto implant surfaces. The kinetics of the enzymatically induced pH increase were studied by monitoring pH, calcium concentration and conductivity of the aqueous solutions as a function of time, urease concentration and initial concentrations of calcium and phosphate ions. Cryogenic Transmission Electron Microscopy (CryoTEM) was used to study the process of homogeneous CaP precipitation in solution, whereas CaP deposition on conventional acid-etched Titanium (Ti) and micropatterned polystyrene (PS) surfaces was studied using Scanning Electron Microscopy (SEM). The data presented in this study confirm that the substrate-enzyme combination urea-urease offers strong control over the rate of pH increase by varying the concentrations of precursor salts and urease. Formation of biomimetic CaP coatings was shown to proceed via formation of ionic polymeric assemblies of prenucleation complexes. The process of deposition and corresponding coating morphology was strongly dependent on the concentration of calcium, phosphate and urease. Finally, it was shown that the substrate-enzyme combination urea-urease allowed for spatial distribution of CaP crystals along the grooves of micropatterned PS surfaces at low concentrations of calcium, phosphate and urease, stressing the sensitivity of the presented method.
AB - The current study has focused on enzymatic decomposition of urea into carbon dioxide and ammonia as a means to increase the pH during biomimetic deposition of Calcium Phospate (CaP) onto implant surfaces. The kinetics of the enzymatically induced pH increase were studied by monitoring pH, calcium concentration and conductivity of the aqueous solutions as a function of time, urease concentration and initial concentrations of calcium and phosphate ions. Cryogenic Transmission Electron Microscopy (CryoTEM) was used to study the process of homogeneous CaP precipitation in solution, whereas CaP deposition on conventional acid-etched Titanium (Ti) and micropatterned polystyrene (PS) surfaces was studied using Scanning Electron Microscopy (SEM). The data presented in this study confirm that the substrate-enzyme combination urea-urease offers strong control over the rate of pH increase by varying the concentrations of precursor salts and urease. Formation of biomimetic CaP coatings was shown to proceed via formation of ionic polymeric assemblies of prenucleation complexes. The process of deposition and corresponding coating morphology was strongly dependent on the concentration of calcium, phosphate and urease. Finally, it was shown that the substrate-enzyme combination urea-urease allowed for spatial distribution of CaP crystals along the grooves of micropatterned PS surfaces at low concentrations of calcium, phosphate and urease, stressing the sensitivity of the presented method.
KW - Calcification
KW - Pre-nucleation clusters
KW - Patterned surfaces
KW - Hydroxyapatite
KW - Calcium phosphate coating
U2 - 10.1016/j.actbio.2013.09.036
DO - 10.1016/j.actbio.2013.09.036
M3 - Article
SN - 1742-7061
VL - 10
SP - 931
EP - 939
JO - Acta biomaterialia
JF - Acta biomaterialia
IS - 2
ER -