Can gold nanoparticles improve delivery performance of polymeric drug delivery systems?

During the recent developments in nanomedicine, gold nanoparticles (Au NPs) have emerged as interesting tools in the field of drug-delivery systems (DDS) due to their low toxicity, stability, easy synthesis and reproducibility [1]. Au NPs are able to link therapeutic molecules on their surface by covalent or noncovalent bonding or by a previous functionalization of Au NPs and release the drug only in a specific site without damaging the healthy tissue [2]. Moreover, the small size of gold NPs allows their accumulation in sites of tumor and inflammation and exhibit fast cell uptake using mechanisms different from those typical of small molecules [3]. Their optical property is characterized by surface plasmon resonance (SPR), by which incident light is converted into heat, which makes them very useful in promoting photothermal drug release [4]. The main drawback resides in the fact that after their administration, if not confined, they escape through the circulatory torrent without reaching the target site and so losing their efficacy. For this purpose, hybrid materials formed by the loading of Au NPs inside polymer networks are studied to improve local drug delivery. In this case, the easy injection and confinement of the hydrogel in the site of injury represent the main advantages together with local release of both small and large molecules in response to thermal stimuli [5].