Colorimetric detection based on gold nano particles (GNPs): An easy, fast, inexpensive, low-cost and short time method in detection of analytes (protein, DNA, and ion)

Gold nanoparticles (GNPs), due to their unique physical and chemical properties, including optical properties, are highly regarded and have extensive applications in biomedical. One of the applications of gold nanoparticles is detection of chemical and biological material, so that these particles are used in detection of materials based on gold nanoparticles being in aggregate and non- aggregate modes and the change in the color of the nanoparticle solution as a result of this change of mode. In the interaction of gold nanoparticles (Bare nanoparticles or functionalized with different compositions) with analytes, aggregate and non-aggregate mode of nanoparticles changes and finally the change in the color of the solution is seen with naked eye without the need for advanced and costly equipment, indicating the presence or absence of target analytes. This change of mode and the subsequent color change is the basis of colorimetric detection based on gold nanoparticles in detection of various analytes. Various analytes can be detected by this method include ion, nucleic acid, proteins and peptides. In this study, we have reviewed various studies performed based on colorimetric detection using gold nanoparticles in detection of various analytes. According to these studies, simplicity, speed, time and cost savings are of considerable benefits of this method, compared to other detection methods. Keywords: Gold nanoparticles, Colorimetric detection, Aggregation, SPIA, Colorimetric immunoassay