Bone-like materials can be used both as bone fillers and drug delivery vehicles for targeting bone cancers, claim Italian scientists. The materials release the drugs over a prolonged period and make them work better than the free drug. 

Norberto Roveri, at the University of Bologna, Italy, and colleagues combined a synthetic bone substitute called hydroxyapatite (HA) with anticancer platinum complexes to produce implantable devices that can control the drugs' release and improve their cytotoxicity. The team hope that by releasing drugs only at target areas, they will be able to avoid the side effects common with anticancer medication.

The group examined the adsorption and release kinetics of platinum complexes on two types of HA nanocrystals, with different sizes, shapes and crystallinities. They found that the nanocrystals absorbed and released the complexes at different rates and in different amounts.

'The HA nanocrystals are able to release antitumoral platinum drugs right on the site of an osteosarcoma [bone cancer] in a slow and controlled manner,' Roveri explains, adding that the HA-drug conjugate is more effective than the free platinum complex. 

'This is a fascinating study that shows the power of combining nanomineralogy and organometallic chemistry, in this case designed for an antitumoral application,' enthuses Michael Hochella, an expert in nanoscience at Virginia Tech, Blacksburg, US. 

'It is the next stage that will be critical, and where many current drug delivery systems fail,' cautions Martin Garnett, an expert on drug-delivery systems at the University of Nottingham, UK. 'Can enough drug be loaded into the system to have a therapeutic effect?' 

Roveri is confident that the system will be effective. 'The large surface area of the nanosized HA particles allows loading of a lot of Pt complex,' he says. Combined with their higher toxicity compared to the non-adsorbed complexes, this smart drug release mechanism should allow a very strong therapeutic effect in situ for a long time, he adds.

Edward Morgan

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