Effect of functional end groups of silane self-assembled monolayer surfaces on apatite formation, fibronectin adsorption and osteoblast cell function

Abstract

Bioactive glass (BG) can directly bond to living bone without fibrous tissue encapsulation. Key mechanistic steps of BG's activity are attributed to calcium phosphate formation, surface hydroxylation and fibronectin (FN) adsorption. In the present study, self-assembled monolayers (SAMs) of alkanesilanes with different surface chemistry (OH, NH 2 and COOH) were used as a model system to mimic BG's surface activity. Calcium phosphate (Ca-P) was formed on SAMs by immersion in a solution that simulates the electrolyte content of physiological fluids. FN adsorption kinetics and monolayer coverage was determined on SAMs with or without Ca-P coating. The surface roughness was also examined on these substrates before and after FN adsorption. The effects of FN-adsorbed, Ca-P-coated SAMs on the function of MC3T3-E1 were evaluated by cell growth, expression of alkaline phosphatase activity and actin cytoskeleton formation. We demonstrate that, although the FN monolayer coverage and the root mean square (rms) roughness are similar on -OH and -COOH terminated SAMs with or without Ca-P coating, higher levels of ALP activity, more actin cytoskeleton formation and more cell growth are obtained on -OH-and -COOH-terminated SAMs with Ca-P coating. In addition, although the FN monolayer coverage is higher on Ca-P-coated -NH 2 -terminated SAMs and SiO x surfaces, higher levels of ALP activity and more cell growth are obtained on Ca-P-coated -OH-and -COOH-terminated SAMs. Thus, with the same Ca-P coatings, different surface functional groups have different effects on the function of osteoblastic cells. These findings represent new insights into the mechanism of bioactivity of BG and thereby may lead to designing superior constructs for bone grafting.

Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

“…A surface with antibacterial properties, high capacity for cell attachment and able to release biological factors could be an effective way to avoid bacteria adhesion and improve osseointegration. Previous studies had suggested that different silanes could affect osteoblasts [8] or present antibacterial activity on steel, Ti6Al4V or glass [9,10]. This study tested in vitro the hypothesis that titanium coated with TESPSA silane has antibacterial properties while inducing osteoblast differentiation.…”

“…In the case of silanization, silane molecules act as a binder between the substrate and the biomolecules. This technique could be improved using silanes that elicit specific cell responses, such as proliferation, differentiation [8] or antibacterial effects [9,10].…”

Silicon Based Nanocoatings on Metal Alloys and Their Role in Surface Engineering

“…Oliviera et al studied the attachment of enzymes on silane SAMs attached to titanium dioxide surfaces [329]. Toworfe et al studied the effect of silane SAM surfaces on apatite formation, fibronectin adsorption and osteoblast cell function [186]. They attached calcium phosphate on the surface of alkylsilane SAMs with different functionalities of (OH, NH 2 and COOH) as a model system to mimic the surface activity of Bioactive Glass (BG).…”

“…Surface modification of polymers like polythiophene has also been carried out using alkylsilane monolayers [185]. The simplest terminal end groups for alkylsilane SAM are methyl, hydroxy, carboxylic and amino groups [2,186]. Researchers have looked into silane SAMs with varying terminal groups like halogen [187][188][189], dicarboxylic [161], cyanide [188], thiocyanide [188], methyl ether [187], acetate [187], thioacetate [187], α-haloacetate [189], tri(methylsilyl) ethynyl [190,191], methyl ester [192,193] and pchloromethylphenyl [189,194,195].…”

Silanization with APTES for Controlling the Interactions Between Stainless Steel and Biocomponents: Reality vs Expectation

“…The survey is exhaustive for stainless steeel substrates relevant for the field of biomaterials and illustrative for other substrates. Additional references are: El-Ghannam et al, 2004;Kim et al, 2010;Sasou et al, 2003;Sarath Babu et al, 2004;Quan et al, 2004 ;Subramanian et al, 1999 ;Jin et al, 2003 ;Cho & Ivanisevic, 2004 ;Katsikogianni & Missirlis, 2010 ;Sordel et al, 2007 ;Toworfe et al, 2006 ;Balasundaram et al, 2006 ;Doh & Irvine, 2006 ;Palestino et al, 2008 ;Son et al, 2011 ;Koh et al, 2006 ;Mosse et al, 2009 ;Weng et al, 2008 ;Charbonneau et al, 2011 ;Iucci et al, 2007 ;Chuang et al, 2006 ;Schuessele et al, 2009 ;Ma et al, 2007 ;Toworfe et al, 2009 ;Zile et al, 2011 ;Sargeant et al, 2008 ;Lapin & Chabal, 2009. Table 1 indicates the substrate and linker used, the main conditions of the APTES treatment and the evaluation of the surface treatment regarding biomolecule activity with the blank used for comparison.…”