Hydroxyapatite foams for the immobilization of heavy metals: From waters to the human body

Heavy metal poisoning is an increasing problem due to the growth of industrial activities that involve manipulation of metals, such as mining, foundries and metallurgy in general. Human exposure to these toxic ions and their absorption during the digestive process results in ion accumulation mainly into bone structure, due to the tendency of ionic exchange chemistry of hydroxyapatite (HA) with metal ions. In the last few years, new improvements on materials processing techniques have opened the door to the development of new forms of material, HA/biopolymer foams. These systems allow heavy metal removal, facilitated by their aqueous stability and integrity 3D-macroporous shape, to provide an easily applicable technology for polluted water that avoids the need for purification procedure steps. Moreover these materials are applicable for biomedical use, to capture and immobilize toxic ions during the digestive process. This work reviews the latest procedures to synthesise and fabricate foams based on HA/biopolymer systems for these goals paying special attention to their heavy metal capture applications. ition, the 3D interconnected architectural design of these HA/biopolymer foams, suggested that they could fit all the requirements to behave as a proper bone scaffold with applications in bone tissue engineering.