Method for production of biocompatible nanoparticles containing dental adhesive
A method of synthesizing hydroxyapatite nanorods, having high purity, high crystallinity and high aspect ratio is disclosed here. In one embodiment, high crystalline hydroxyapatite nanorods with relatively stoichiometric structure are prepared via hydrothermal method at 200° C. and under moderate acidic conditions. The synthesized hydroxyapatite nanorods have a diameter of 30-95 nm, a length of 850-1400 nm with an average aspect ratio of 24, degree of crystallinity of 73% and stoichiometry ratio of 1.69. Further it discloses the use of HAp in dental adhesive. The dental adhesive comprising synthesized HAp shows improved diametral tensile strength and high microshear bond strength. Energy dispersive X-ray mapping confirmed the uniform distribution of nanorods in the adhesive matrix. The synthesized hydroxyapatite nanorods have high colloidal stability in the dental adhesive solution. The nanorods are well dispersed and protected from aggregation by their high surface charges confirmed by zeta potential measurement.
1. A method of synthesizing hydroxyapatite nanorods (HAp) having purity, crystallinity, aspect ratio comprises:
preparing an ionic solution of calcium ion (Ca 2+ ) by dissolving Ca(NO 3 ) 2 ·4H 2 O salt in deionized water;
preparing an ionic solution of phosphate ion (HPO 4 2− ) by dissolving (NH 4 ) 2 HPO 4 salt in deionized water;
adding said phosphate ion solution in drop wise into said calcium ion solution with continuous stirring to obtain a reaction mixture;
adjusting molar ratio of said calcium to said phosphate ion solutions, Ca/P to about 1.67;
performing a chemical precipitation reaction of said reaction mixture under alkaline or acidic conditions to obtain a HAp precursor suspension in water wherein said alkaline condition is obtained by adding urea or ammonia solution to said reaction mixture;
performing a hydrothermal treatment of said HAp precursor suspension in water in a 100 ml auto-clave at a temperature about 90 or 200° C. for 60 hrs to obtain suspension of HAp nanorods, washing said suspension of HAp nanorods in a deionized water;
performing filtration of said suspension of HAp nanorods by centrifugation to obtain a nanosized Hap rods;
and crushing said nanosized HAp rods to powder form.
2. The method according to claim 1 , wherein said nanosized Hap rods is selected from a group consisting of nanosized HAp particles wherein said particles having different structural and morphological properties are obtained by varying the concentration of reactants, temperature, pH of said reaction mixture and further said reactants comprises of phosphate ion, calcium ion and urea.
3. The method according to claim 2 , wherein said structural and morphological properties includes: diameter; length; aspect ratio and degree of crystallinity of said nanosized HAp rods.
4. The method according to claim 1 , wherein said nanosized HAp rods has a diameter of about 35-320 nm.
5. The method according to claim 1 , wherein said nanosized HAp rods has a length of about 850-1400 nm.
6. The method according to claim 1 , wherein said nanosized HAp rods has an aspect ratio of about 24.
7. The method according to claim 1 , wherein said nanosized HAp rods has crystallinity of about 73%.
8. A dental adhesive composition comprising:
0.2-0.5 wt % of nanosized HAp rods;
39.5-39.8 wt % of Ethanol;
12 wt % of 1,6-bis-[2-methacryloyloxy ethoxycarbonylamino]2,4,4-trimethylhexane (UDMA);
14 wt % of 2,2-bis[p-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (Bis-GMA);
26 wt % of 2-hydroxyethyl methacrylate (HEMA);
and 8 wt % of 2-Ethyl-2-(hydroxymethyl)-1,3-propandiol trimethacrylate (TMPTMA) mixed in given proportions to achieve a preset mechanical strength and a bond strength to dentin.
9. The composition according to claim 8 further comprising a photoinitiating system wherein said photoinitiating system is CQ/DMADME.
10. The composition according to claim 8 , wherein the nanosized HAp rods are synthesized by
preparing an ionic solution of calcium ion (Ca 2+ ) by dissolving Ca(NO 3 ) 2 ·4H 2 O salt in deionized water;
preparing an ionic solution of phosphate ion (HPO 4 2− ) by dissolving (NH 4 ) 2 HPO 4 salt in deionized water;
adding said phosphate ion solution in drop wise into said calcium ion solution with continuous stirring to obtain a reaction mixture;
adjusting molar ratio of said calcium to said phosphate ion solutions, Ca/P to about 1.67;
performing a chemical precipitation reaction of said reaction mixture under alkaline or acidic conditions to obtain a HAp precursor suspension in water wherein said alkaline condition is obtained by adding urea or ammonia solution to said reaction mixture;
performing a hydrothermal treatment of said HAp precursor suspension in water in a 100 ml auto-clave at a temperature about 90 or 200° C. 60 hrs to obtain suspension of HAp nanorods, washing said suspension of HAp nanorods in a deionized water;
performing filtration of said suspension of HAp nanorods by centrifugation to obtain a nanosized Hap rods;
and crushing said nanosized HAp rods to powder form.
11. The composition according to claim 8 , wherein a synthesized HAp without any surface modification is colloidal stable in said composition.
12. The composition according to claim 8 , wherein said preset mechanical strength is diametral tensile strength of at least 34 MPa.
13. The composition according to claim 8 , wherein said preset mechanical strength is flexural strength of at least 51 MPa.
14. The composition according to claim 8 , wherein 0.2 wt % of the HAp improves the bond strength to about 22 MPa.