1. Hydroxyapatite-carbon composite materials
Kulak Anatoly, Krutsko Valiantsina
Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus
Belarus, Minsk, Surganova Str. 9,
Hydroxyapatite (HA) Са10(РО4)6(ОН)2 have been widely used in clinical applications due to their close similarity and high biocompatibility with natural bone. The main goal of this work is the elaboration of highly biocompatible composite materials based on nanocrystalline HA and various matrix (cellulose, carbon, polyvinyl alcohol (PVA), stainless steel, porous ceramic) suitable for bone substitution and reconstruction.
The HA gel was prepared by the interaction between of CaCl2 and (NH4)2HPO4 solutions with Ca/P ratio 1.67 at pH 1011. Cellulose was modified by HA in the form of gel (concentration of dried substance is 3–5%) or 37% powder with 3–5% PVA solution. Cellulose is used an initial station and phosphorylated with exchange capacity of 0.8; 1.7; 3.4 mg-eq/g. The increase of treatment time by HA gel result in the HA quantity grows in 1.52.0 times and its maximum observed for phosphorylated cellulose (3.4 mg-eq/g) was established.
Carbon fibers and felts were modified by HA gel together with 5% PVA solution. The absorbed HA quantity is grown to the direct proportion at treatment time from 5 to 60 min. Such composite materials can be used for replacement of bone defects in traumatic surgery, oral surgery, ophthalmology etc. a b a b c
SEM observations of phosphorylated cellulose without HA (a) and with HA (b)
The electrochemical deposition of calcium phosphate coatings onto stainless steel substrates in СаCl2/ NH4H2PO4 electrolyte under mild conditions (room temperature, current density of 210 mA/cm2) has been elaborated. It was shown that the main components of such coatings are dicalcium phosphate dihydrate (brushite) CaНPO42Н2О, tricalcium phosphate Ca3(PO4)2, and HA. The content of HA in the coatings increases with increasing time of deposition from 1.0 to 2.5 h, concentration of NH4H2PO4 from 0.7 to 1.4 M and current density from 2 to 10 mA/cm2.
The drug based on HA gel and intended for a direct injection into the bone defects has been elaborated. The Technical Specifications for the HA
HA consisted composite materials based on PVA (a), carbon fiber (b) and felt (c) modified with PVA/ HA a b
SEM observations of calcium phosphate coatings
gel production at Republican Unitary Enterprise “Belmedpreparaty” has been developed. The clinical trials of this drug confirmed its high specific activity in the processes of bone regeneration. b a
A novel kind of light, moveable ophthalmologic and proctologic implants based on porous alumina foam ceramics modified with 10% nanocrystalline HA has been devised. Pre-clinical and clinical trials of these ophthalmologic implants with 26 patients involved have been successfully carried out.
Ophthalmologic (a) and proctologic (b) implants modified HA
HA gel for bone injection