Mesoporous titania coatings with carboxylated pores for complexation and slow delivery of strontium for osteogenic induction

[Display omitted] •Pores in mesoporous titania are functionalized with carboxylates and complex Sr ions.•Sr is released from the mesoporous with an initial burst and then slowly over weeks.•Sr release from mesoporous improves MC3T3-E1 cell adhesion and proliferation rate. The release of bioactive Strontium ions (Sr2+) from titanium implants has a positive impact on osseointegration. It is however challenging to achieve a slow Sr2+ release over weeks until tissue regeneration. A hybrid mesoporous titania film (MTF) displaying carboxylic moieties in pore walls has been developed here for encapsulation and slow delivery of Sr2+. Mesoporous films are prepared by Evaporation Induced Self-Assembly. Vinyltrimethoxysilanes are co-condensed during film assembly and vinyl groups of silanes are reacted with mercaptosuccinic acid resulting in pores displaying carboxylic groups. Modified MTFs are loaded with Sr2+, which is retained both as non-complexed ion in the pores and complexed to the carboxylic acid groups. The complexation of Sr2+ to the carboxylic groups is proven by X-ray Photoelectron Spectroscopy and Infrared Spectroscopy. Inductively Coupled Plasma Mass Spectrometry shows that the non-complexed Sr2+ is released from the pores in approximately one day while complexed Sr2+ is released slowly over one week. The released Sr2+ has a positive effect on MC3T3-E1 pre-osteoblastic cell proliferation and the Alkaline Phosphatase test shows that at 15 days of culture in osteogenic medium the differentiation is enhanced due to the slow release of Sr2+ complexed to carboxylates.