A multi-material coating containing chemically-modified apatites for combined enhanced bioactivity and reduced infection via a drop-on-demand micro-dispensing technique

  • Poon Nian Lim
  • Zuyong Wang
  • Lei Chang
  • Toshiisa Konishi
  • Cleo Choong
  • Bow Ho
  • Eng San Thian
Biomaterials Synthesis and Characterization Original Research
Part of the following topical collections:
  1. Biomaterials Synthesis and Characterization


Prevention of infection and enhanced osseointegration are closely related, and required for a successful orthopaedic implant, which necessitate implant designs to consider both criteria in tandem. A multi-material coating containing 1:1 ratio of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite as the top functional layer, and hydroxyapatite as the base layer, was produced via the drop-on-demand micro-dispensing technique, as a strategic approach in the fight against infection along with the promotion of bone tissue regeneration. The homogeneous distribution of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets at alternate position in silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating delayed the exponential growth of Staphylococcus aureus for up to 24 h, and gave rise to up-regulated expression of alkaline phosphatase activity, type I collagen and osteocalcin as compared to hydroxyapatite and silver-substituted hydroxyapatite coatings. Despite containing reduced amounts of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets over the coated area than silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite coatings, silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating exhibited effective antibacterial property with enhanced bioactivity. By exhibiting good controllability of distributing silicon-substituted hydroxyapatite, silver-substituted hydroxyapatite and hydroxyapatite micro-droplets, it was demonstrated that drop-on-demand micro-dispensing technique was capable in harnessing the advantages of silver-substituted hydroxyapatite, silicon-substituted hydroxyapatite and hydroxyapatite to produce a multi-material coating along with enhanced bioactivity and reduced infection.


Hydroxyapatite Osteocalcin Coated Sample Microbial Adhesion Vortexed Solution 



This work was supported by the Ministry of Education Academic Research Fund (Singapore) Project number MOE2013-T2-1-074.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.


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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Poon Nian Lim
    • 1
  • Zuyong Wang
    • 1
  • Lei Chang
    • 1
  • Toshiisa Konishi
    • 1
    • 2
  • Cleo Choong
    • 3
  • Bow Ho
    • 4
  • Eng San Thian
    • 1
  1. 1.Department of Mechanical EngineeringNational University of SingaporeSingaporeSingapore
  2. 2.Graduate School of Natural Science and TechnologyOkayama UniversityOkayamaJapan
  3. 3.School of Materials Science and Engineering, Nanyang Technology UniversitySingaporeSingapore
  4. 4.Department of Microbiology and Immunology, Yong Loo Lin School of MedicineNational University of SingaporeSingaporeSingapore

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