Design of pH-responsive gold nanoparticles in oncology

Abstract

Gold nanoparticles (AuNPs) hold promising applications in many fields such as electronics, optics and catalysis. In the past decades, there has been a growing interest for their application in medicine, in particular in nano-oncology as contrast agents, drug delivery vehicles or for diagnosis. Once injected intravenously and thanks to their small size, the AuNPs can circulate in the whole body via the blood stream and reach easily the tumour. However, what makes them very attractive for cancer treatment is their ability to distinguish healthy cells from cancer cells. While the current anticancer agents lack specific targeting, AuNPs, with their targeting efficiency, will enable the use of lower amount of drugs with all the positive aspects for the health of the patient. Additionally, their optical properties give them the ability to be used in imaging as an incredibly powerful contrast agent. For these reasons, they are believed to be one of the tools that, in the future, will enable to considerably increase the efficiency of cancer treatments by simultaneously imaging the tumour and treat it. They constitute an ideal theranostic drug delivery platform, in other words a unique combination of diagnostics and therapy. Many researches focus on the engineering of the nanoparticle surface in order to increase their biocompatibility and enable their further conjugation with bioactive ligands such as drugs, targeting or imaging agents for the design of multifunctional platforms. pH responsiveness, the ability to change properties with a change of proton concentration, is a remarkable asset for drug delivery carrier. Indeed, it has been demonstrated that cancer cells show very particular pHs in their environment: extracellular as well as intracellular. This characteristic has been exploited to create a more specific and efficient way to treat cancer. The present review focuses on the design of pH responsive AuNPs and particularly on the advantages and the potential applications of such hybrid nanomaterials in oncology.