Transition metal doped hydroxyapatites: from chemistry to antibacterial properties

Abstract

Musculoskeletal disorders are one of the leading causes of disability. Currently, 1.3 billion population across the globe are suffering from various musculoskeletal disorders (MSK) and it imposes a total of $ 136.8 billion annual burden to the US economy. Current treatment options consist of pain medication and surgical intervention by inserting implants and scaffolds on the affected site. Hydroxyapatite [HA, Ca10(PO4)6OH2] based implants are widely preferred for tissue engineering applications due to their compositional similarities with human bone. However, post-surgical infections on the implant surface often cause implant failure and need to be rectified by three times costlier revision surgery. The flexible crystal chemistry of hydroxyapatite allows transition metal substitution both in the cationic and anionic sites due to the ionic radius differences between calcium and first row transition metals. Transition metal substitutions incorporate exiting biological and antibacterial properties to HA. This paper will summarize the available literature reports which describe the crystal chemistry of first row transition metal incorporation in HA and the resulting antibacterial properties.