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Quantifying effects of interactions between polyacrylic acid and chlorhexidine in dicalcium phosphate - forming cements

Xia, W; Razi, MRM; Ashley, P; Abou Neel, EA; Hofmann, MP; Young, AM; (2014) Quantifying effects of interactions between polyacrylic acid and chlorhexidine in dicalcium phosphate - forming cements. JOURNAL OF MATERIALS CHEMISTRY B , 2 (12) 1673 - 1680. 10.1039/c3tb21533d. Green open access

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Abstract

The aim of this study was to assess how varying the ratio of aqueous 0.8 M citric acid[thin space (1/6-em)]:[thin space (1/6-em)]6 M polyacrylic acid (PAA) (3[thin space (1/6-em)]:[thin space (1/6-em)]0, 1 or 3 by weight) affected setting chemistry, mechanical properties and chlorhexidine di-acetate (CHX) release of dicalcium phosphate – forming bone cements. Cement powder included β-tricalcium phosphate (β-TCP)[thin space (1/6-em)]:[thin space (1/6-em)]monocalcium phosphate monohydrate (MCPM)[thin space (1/6-em)]:[thin space (1/6-em)]CHX at 1[thin space (1/6-em)]:[thin space (1/6-em)]1[thin space (1/6-em)]:[thin space (1/6-em)](0, 0.08 or 0.16) molar ratio. Powder to liquid ratio was fixed at 3[thin space (1/6-em)]:[thin space (1/6-em)]1 by weight. Chemical setting kinetics, reactive intermediate formation and final product homogeneity were assessed by ATR FTIR and Raman mapping. Biaxial flexural strength and modulus were determined after 24 hours setting plus 24 hours in water at 37 °C and analysed using Weibull type equations. CHX release from 1 mm thick set discs was assessed over 4 weeks using UV spectroscopy. FTIR demonstrated that CHX interaction with citric acid inhibited formation of the reactive citrate/dicalcium phosphate intermediate complex that enables delay before snap set. High CHX additionally increased strength variability. Upon partial citric acid substitution with higher levels of PAA, delay before cement set was maintained. Monetite instead of brushite, however, was formed in conjuction with more stable polyacrylate complexes. These formulations had much improved strength but also greater modulus. CHX addition and interaction with PAA encouraged greater brushite instead of monetite formation. These complex interactions enabled formulations with high drug and PAA to have improved strength without increase in modulus. They also had low strength variability and better (slower) controlled release of drug. These properties are beneficial for cement use in a range of orthopaedic and dental applications.

Type: Article
Title: Quantifying effects of interactions between polyacrylic acid and chlorhexidine in dicalcium phosphate - forming cements
Open access status: An open access version is available from UCL Discovery
DOI: 10.1039/c3tb21533d
Publisher version: http://dx.doi.org/10.1039/c3tb21533d
Additional information: © The Royal Society of Chemistry 2014. This Open Access Article is licensed under aCreative Commons Attribution 3.0 Unported Licence
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Biomaterials and Tissue Eng
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > EDI Craniofacial and Development Sci
URI: https://discovery.ucl.ac.uk/id/eprint/1423404
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