Gold nanocrystals as potential inhibitors of tumor angiogenesis: implications in diagnosis and drug delivery

Angiogenesis is considered one of the hallmarks in tumor biology which contributes to metastasis and tumor progression by promoting the growth and development of blood vessels in order to supply nutrients and oxygen to the growing cancer cells. Numerous attempts have been made to target the mechanism of angiogenesis, out of which the most approachable method is the administration of angiogenesis inhibitors to target the growth of new blood vessels, which seems to be a powerful tool in targeted drug delivery when incorporated into nanocarriers and directed towards the tumor site. The main objective of this review is to focus on the importance of gold nanocrystals as an emerging tool in targeting tumor angiogenesis, and thereby facilitate tumor diagnosis and therapy. This review deals with the remarkable physicochemical and biological features of gold nanocrystals that make them ideal drug delivery systems. It gives an overview of the preclinical and clinical studies carried out using gold nanocrystals and also describes the recent advances in the applications of gold nanocrystals in tumor diagnosis, imaging, photodynamic therapy, and drug delivery, along with their limitations. Gold nanocrystals have proven to show promising effects in tumor-specific delivery of the drugs and are beneficial in reducing the undue effects on the surrounding normal cells and also in enhancing the intratumoral drug accumulation. Hence, they could be exploited as potential antiangiogenic agents and as targeted cancer therapeutics.