Investigation of adsorption of albumin on synthesized nano-sized silicon-substituted hydroxyapatite

Abstract

Having similarity to bone tissue in terms of chemical composition, with high bio-compatibility and
bio-activity, materials based on synthetic hydroxyapatites, including silicon-substituted hydroxyapatite, have
found wide application in medicine practice (dentistry, orthopedics, cosmetics and surgery) as ceramics,
cements, composites, etc. Creating the optimal nanotechnology based on nanosized unmodified and modified
hydroxyapatites of medicinal and transport forms to solve the problems in the prophylaxis and treatment of
bone diseases, osteoporosis and calcium deficiency requires information on the mechanisms and the laws of
processes involving hydroxyapatites, taking place in the human body. Therefore, studying the interaction of
hydroxyapatite nanoparticles with bio-macromolecules, in particular proteins, has gained a special
importance.
The aim of this study was to determine the sorption features of albumin on nanosized synthetic
silicon-substituted hydroxyapatites. Single-phase nanosized silicon-substituted hydroxyapatite with an
average size of 12-20 nm was synthesized by the method of precipitation from aqueous solution. The texture
characteristics and morphology of the Si-HAP samples were determined using the methods of FTIR, XRD,
Ле Ван Тхуан и др. / Сорбционные и хроматографические процессы. 2015. Т. 15. Вып. 1
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TEM and BET. It was revealed that crystals of Si-HAP have needle-like shape with a length of 40-120 nm
and thickness of 4-8 nm. The introduction of silicate ions in the lattice causes a decrease in the size of the
HAP crystals of almost 3.5 times and an increase in the specific surface area of about 4.5 times. With
increasing degree of silicon substitution the crystal size increases.
Experiments on sorption features of albumin on the surface of different samples of Si-HAP were
conducted, in which the isotherms and adsorption parameters were obtained. The maximum adsorption
capacity of albumin on samples of Si-HAP was 119-167 mg/g. By increasing the degree of silicon
substitution, the specific surface area of the samples increases, therefore so does the adsorption capacity. The
mechanism and kinetics of the adsorption/desorption processes were also investigated. It was found that one
of the adsorption features of albumin on synthetic Si-HAP is the participation of electrostatic forces. Based
on the results of the study it can be assumed that synthetic Si-HAP is a perspective biomaterial of medical
applications and a sorbent for the separation of proteins and other substrates.