Adsorption and bioactivity studies of albumin onto hydroxyapatite surface

Abstract

Bovine serum albumin (BSA) may have an inhibitory or promoter effect on hydroxyapatite (HA) nucleation when apatite is precipitated in a medium containing the protein. In this study we evaluated the influence of BSA on the precipitation of calcium phosphate phases (CP) from simulated body fluid (SBF) when the protein was previously bounded to HA surface. The kinetics of BSA immobilization onto hydroxyapatite surface was performed in different buffers and protein concentrations in order to adjust experimental conditions in which BSA was tightly linked to HA surface for long periods in SBF solution. It was shown that for BSA concentration higher than 0.1mg/mL the adsorption to HA surface followed Langmuir-Freundlich mechanisms, which confirmed the existence of cooperative protein-protein interactions on HA surface. Fourier Transformed Infrared Attenuated Total Reflectance Microscopy (FTIRM-ATR) evidenced changes in BSA conformational state in favor of less-ordered structure. Analyses from high resolution grazing incident X-ray diffraction using synchrotron radiation (GIXRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed that a poorly crystalline calcium phosphate was precipitated on the surface of HA discs coated with BSA, after the immersion in SBF for 4 days. The new bioactive layer had morphological characteristics similar to the one formed on the HA surface without protein. It was identified as a carbonated apatite with preferential crystal growth along apatite 002 direction. The GIXRD results also revealed that BSA layer bound to the surface inhibited the HA dissolution leading to a reduction on the formation of new calcium phosphate phase.

Response of osteoblasts and preosteoblasts to calcium deficient and Si substituted hydroxyapatites treated at different temperatures

“…On the other hand, recent studies demonstrate a reduced in vitro bioactivity of HA surface coated with BSA in comparison to the uncoated surface [48]. The lower BSA and fibrinogen adsorption on samples treated at 1250ºC compared with those treated at 700ºC suggests a better tissue response to CDHA-1250 and SiHA-1250 scaffolds, in agreement with the cell proliferation results (Fig.…”

Roles of interstitial fraction and load conditions on the dynamic binding capacity of proteins on capillary‐channeled polymer fiber columns

“…[53][54][55] BSA is well known to multilayer in static systems. 56,57 The most common model used to describe adsorbate-adsorbate interactions, following the initial establishment of a monolayer, is the Moreau isotherm, 42,58 presented as:…”

Needle-Free Dermal Delivery of a Diphtheria Toxin CRM197Mutant on Potassium-Doped Hydroxyapatite Microparticles

“…When related to the particle surface area, which was obtained from the light-scattering particle size distribution, the maximum CRM 197 adsorption capacity corresponds to a K-Hap surface protein-loading density of 9.7 mg/m 2 . The protein-loading density of BSA on pure hydroxyapatite has been reported as 1.5 mg/m 2 , but buffer strength, protein type, and substrate can affect the loading density and may therefore not be compared directly to the results presented in this paper (40). Additionally, light scattering can give an estimate of the surface area, but it cannot account for the surface roughness.…”