On The Applications Of Nano-hydroxyapatite In The Consolidation Of Ancient Ivory And QCM-D Sensors

Due to the excellent biocompatibility,hydroxyapatite is one of the most promising biomaterials.Recently,hydroxyapatite has been widely used in bone replacement,dental implant,catalyst agent and drug delivery.However,little research work has been carried out on the applications of hydroxyapatite in the consolidation of ancient ivory and the sensors of quartz crystal microbalance with dissipation(QCM-D).Study of the consolidation effect of nano-hydroxyapatite on Jinsha site ancient ivory would be helpful to extend the application of the nano-hydroxyapatite and then provide a valuable insight into the preservation of cultural relics.Most researchers used QCM-D technique to study the adsorption kinetics of salivary proteins,and it has been increasingly recognized that hydroxyapatite sensor may be more suitable in comparison with traditional gold sensor.QCM-D hydroxyapatite sensor relies on imports and is expensive nowadays.Thus,it is very necessary to develop domestic hydroxyapatite sensor so as to reduce experimental cost.In this study,the applications of nano-hydroxyapatite in the consolidation of ancient ivory and QCM-D sensors were investigated.Jinsha site ancient ivory was consolidated through impregnation treatment with the hydroxyapatite nano-particles synthesized by hydrothermal method.The morphology and mechanical properties of ivory surfaces were examined using SEM and nano-indentation/scratch technique.A hydroxyapatite sensor was fabricated through coating nano-hydroxyapatite on the surface of QCM-D gold sensor by means of electrophoretic deposition method and ultrasound treatment.The adsorption dynamic process of salivary proteins on the self-made hydroxyapatite sensor was studied and compared with that on traditional QCM-D gold sensor.The main results and conclusions were drawn as below.(1)After consolidating with nano-hydroxyapatite,an even and compact hydroxyapatite nano-particle deposition layer was formed on the surface of ancient ivory,while no obvious changes occurred to its color and surface texture.Compared with the original ivory surface,the nanoindentation hardness and Young's modulus of the consolidated ivory surface obviously increased.Both the friction coefficient and wear volume of the ivory surface decreased after consolidation.It seems that nano-hydroxyapatite is a promising consolidant for Jinsha site ancient ivory.The consolidation with hydroxyapatite nano-particles could improve the mechanical and anti-wear properties of ancient ivory surface but neither introduce extraneous substances nor influence its appearance.And the consolidated layer can act as a covering to isolate the ivory with outer environment and then prevent it from further deterioration.(2)A nano-hydroxyapatite coating could be fabricated on the surface of traditional QCM-D gold sensor using electrophoretic deposition and ultrasound treatment.When suspension concentration was 30 g/L and electric field intensity was 150 V/cm,the surface of QCM-D gold sensor was coated with a 35 nm thick layer of hydroxyapatite crystals evenly covering and tightly bound to the matix,and then the sensor could be used as QCM-D hydroxyapatite sensor.(3)The adsorption behavior of salivary proteins on hydroxyapatite sensor differed from that on gold sensor.The salivary pellicle had larger thickness and viscoelasticity on gold sensor but had higher degree of hydration on the self-made hydroxyapatite sensor.