Abstract
Gold nanoparticles possess great features to become an ideal tool for biological systems due to their high biocompatibility upto a fairly high concentration, in addition to several other special properties. But synthesis of gold nanoparticles poses potential environmental and biological risks. Typical known method generally involves reduction of gold metal ions using harsh reducing agents such as hydrazine, sodium borohydrate, dimethyl formamide, which are highly reactive and toxic to both human cells and environment. Other problem is associated with the relative instability of gold nanoparticles as they tend to quickly agglomerate and oxidize. Known stabilization methods include storage in citrate and use of thiols. However, citrates can be strongly acidic making their handling and use difficult, while, thiols cannot be readily exchanged onto peptides or other biomolecules because of strong interaction of gold metal with the thiols. The present study uses a novel method to allow the synthesis of monodispersed gold nanoparticles of 8-35 nm sizes using trypsin as a reducing agent and Human Serum Albumin (HSA) as a capping agent in aqueous solution under controlled conditions. Gold nanoparticles synthesized by this method are highly stable and can be kept at room temperature for months. Thus, this method provides an environmental friendly approach for fabricating different size gold nanoparticles using trypsin (serine protease) which have long-term stability even at room temperature.