A Rapid and Sensitive Colorimetric Sensor for Detection of Silver Ions Based on the Non-aggregation of Gold Nanoparticles in the Presence of Ascorbic Acid

In the present work, we have developed a label free, colorimetric and non aggregation based gold nanoparticle (Au NPs)/Ascorbic acid (AA) probe without employing any aggregation agents for detection of trace amounts of silver ions (Ag+ ions) in aqueous solution and water samples. This detection probe can be prepared by simply mixing Au NPs with AA. The sensing mechanism is based on the reduction of Ag+ to Ag-0 on the surface of Au NPs by AA. The addition of Ag+ ions to Au NPs/AA probe resulted in the enhancement and simultaneous blue shift of surface plasmon resonance band of Au NPs at 512 nm and it is accompanied by the appearance of a new peak around 385 nm. These observations are attributed to the deposition of Ag-0 on the surface of Au NPs. This method could selectively detect Ag+ ions and showed a good linearity over the range of 2-28 mu M (LOD = 0.85 mu M). This sensing strategy avoids complex surface modification of Au NPs and it is cost effective.