APPLICATIONS OF PLASMONIC AND METAL-SEMICONDUCTOR COMPOSITE NANOPARTICLES

• Gold nanoparticles based detection of carcinogenic heavy metalHg²⁺ ions present in water.
• Tri-sodium citrate capped gold nanoparticles in aqueous media exhibit characteristic red color with localized surface plasmon resonance (LSPR) wavelength at about 530 nm.
• In presence of thiol group compounds, inter particle separation (gold nanoparticles) decreases and results into inter-particle coupled plasmon resonance shows change of LSPR wavelength or color of the solution (Fig. 17).



2+ ion concentration from left: 30 μM, 3 μM, 300 nM, 30 nM, 10 nm, 1 nM and without Hg2+ ">

Fig. 18 Typical colorimetric changes of the gold nanoparticles with decreasing the Hg2+ ion concentration from left: 30 μM, 3 μM, 300 nM, 30 nM, 10 nm, 1 nM and without Hg2+



• Demonstration of detection of Hg²⁺ ions in aqueous samples with concentrations of about 50 ppb, detectable to naked eye based on colorimetric sensing.
• This method based on plasmonic effects of gold nanoparticles is a simple, versatile and cost effective way for detection of toxic heavy metal ions with ppb level of detection limit.