Enhanced model protein adsorption of nanoparticulate hydroxyapatite thin films on silk sericin and fibroin surfaces

Muhsin Çiftçioğlu,Selçuk Özcan

doi:10.1007/s10856-021-06632-5

Muhsin Çiftçioğlu, Selçuk Özcan

Open Access

https://doi.org/10.1007/s10856-021-06632-5

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Abstract

Hydroxyapatite coated metallic implants favorably combine the required biocompatibility with the mechanical properties. As an alternative to the industrial coating method of plasma spraying with inherently potential deleterious effects, sol-gel methods have attracted much attention. In this study, the effects of intermediate silk fibroin and silk sericin layers on the protein adsorption capacity of hydroxyapatite films formed by a particulate sol-gel method were determined experimentally. The preparation of the layered silk protein/hydroxyapatite structures on glass substrates, and the effects of the underlying silk proteins on the topography of the hydroxyapatite coatings were described. The topography of the hydroxyapatite layer fabricated on the silk sericin was such that the hydroxyapatite particles were oriented forming an oriented crystalline surface. The model protein (bovine serum albumin) adsorption increased to 2.62 µg/cm2 on the latter surface as compared to 1.37 µg/cm2 of hydroxyapatite on glass without an intermediate silk sericin layer.The BSA adsorption on glass (blank), glass/c-HAp, glass/m-HAp, glass/sericin/c-HAp, and glass/sericin/m-HAp substrates, reported as decrease in BSA concentration versus contact time.

Highlights

The formation of hydroxyapatite in vivo as the mineral constituent of bone and teeth tissue is closely related to the physiology of calcium and phosphate metabolism in vertebrates
The maximum adsorption of bovine serum albumin (BSA) was on glass/sericin/c-HAp film, 2.6 μg/cm2, a result evidencing the effectiveness of surface topographical structure as well as the chemical structure for BSA adsorption on hydroxyapatite surfaces
The high affinity of the silk proteins for BSA and collagen type I were confirmed by atomic force microscope (AFM) imaging

Summary

Introduction

The formation of hydroxyapatite in vivo as the mineral constituent of bone and teeth tissue is closely related to the physiology of calcium and phosphate metabolism in vertebrates. The embodiment of hard tissue implants to the host bone tissue is achieved through morphological fixation, osteoconduction, osseointegration, chemical adhesion, or time regulated resorption, with healing accelerated osteoinductively, governed by the closely related biological and chemical processes. Biocompatible mineral coatings of CaP allow a variety of materials to be employed as in vivo hard tissue implants [3, 4] They act as local scaffolds for enhanced osteoconduction by osteogenic cell migration, proliferation, and differentiation on the implant surface (osteoinduction) resulting in ingrowth of the surrounding hard tissue. Some of the HAp coatings achieved by the sol-gel techniques, especially, when HAp forms in-situ during the coating process, yields an amorphous or poorly crystalline HAp layer that may suffer the drawbacks due to the amorphous HAp phase as in plasma spraying [6]

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