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Effect of functional end groups of silane self‐assembled monolayer surfaces on apatite formation, fibronectin adsorption and osteoblast cell function
Author(s) -
Toworfe G. K.,
Bhattacharyya S.,
Composto R. J.,
Adams C. S.,
Shapiro I. M.,
Ducheyne P.
Publication year - 2009
Publication title -
journal of tissue engineering and regenerative medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.835
H-Index - 72
eISSN - 1932-7005
pISSN - 1932-6254
DOI - 10.1002/term.131
Subject(s) - monolayer , chemistry , alkaline phosphatase , adsorption , silane , protein adsorption , fibronectin , osteoblast , biophysics , self assembled monolayer , chemical engineering , cell , biochemistry , organic chemistry , in vitro , enzyme , biology , engineering
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. Copyright © 2008 John Wiley & Sons, Ltd.