Frankincense resin mediated green method for optimized biosynthesis of gold nanoparticles for simple and visual detection of Cu2+ ions

Abstract

Abstract We established a green and sustainable method for the synthesis of biogenic gold nanoparticles (AuNPs) using frankincense resin. Frankincense resin acts as a good stabilizing and reducing agent. A label free and portable colorimetric probe of AuNPs was established for sensing of copper metal (Cu2+) ions. The synthesis of AuNPs was optimized by varying the microwave irradiation time, concentrations of frankincense resin, and HAuCl4. Frankincense resin stabilized AuNPs were characterized by utilizing UV–Visible, FTIR, XRD, and TEM analysis. TEM showed a well dispersed spherical shape of AuNPs with an average size distribution of 12 ± 2 nm. The AuNPs showed good response to selective colorimetric detection of Cu2+ ions with a color change from red to blue and sensing was monitored by UV–Visible spectrophotometer. The SPR peak of frankincense resin stabilized AuNPs peak at 525 nm was decreased by aiding Cu2+ metal ion and simultaneously a new peak observed at 648 nm it is due to chelation between Cu2+ ions and surface functional groups of AuNPs. It concludes AuNPs shows the high selectivity for sensing of Cu2+ ions. The developed system shows an excellent linear correlation (R2 = 0.92) in the range of 50–550 nM of copper along with a threshold detection 50 nM. To the study of the impact of other metal ions on Cu2+ binding to AuNPs, competitive investigations were carried out in the presence of Al3+, Mg2+, Ni2+, Sn2+, Co3+, Zn2+, Mn2+ and Hg2+. The developed technique could be used for detection of Cu2+ in real water samples. The developed method is cheap, portable and it can be used in biomedical and environmental applications.