State-of-Art Gold Nanoparticles

**3**

**Chapter 1**

**1. Introduction**

nanoparticles.

**2. Literature survey**

Introductory Chapter: Basic

Concept of Gold Nanoparticles

*Mohammed Muzibur Rahman and Abdullah Mohamed Asiri*

Nanoscience and nanotechnology are generally used in the design, production, characterization, and potential applications of nanostructural materials especially considering their size as well as shape. Nanoscience is a phenomenon that occurs in structures of nanodimensions. Generally, the unique features of nanosystems arise exclusively from the small size of the systems. Here, nano is the smallest dimension as it is obtained in the world in various branches of chemistry, physics, drug design, semiconductor materials science, and even biological science. The hydrogen atom diameter is about 1/10 of a nanometer; therefore, the nanometer dimension or scale is the very tiny scale on what we might consider the building objects or machines on the fundamental basis of the principles in where from everyday mechanics. By using the 1000 as well as hydrogen atoms it could be picked into a cubic object. Nanoscience and nanotechnology are cumulative designations referring to each practical technology and instrumental science, which function with nanodimensional scale or objects. Basically, low-dimensional nanoparticles have various significant properties compared to those of larger objects/particles, and these characteristic properties could be utilized in a broad spectrum of areas of medicine, catalysis, information technologies, renewable energy production, renewable energy storage, ultrasensitive sensors, devices, materials, manufacturing, surfactants, and environmental applications. Basically, the development of green nanotechnology is generating interest in researchers toward eco-friendly, safe, and non-toxic routes of synthesis that can be used for manufacturing at a large scale. This is a simple, cost-effective, stable for long time, and reproducible aqueous room temperature synthesis method to obtain a self-assembly of gold

Generally, colloidal gold is a kind of sol or colloidal suspension, which is called nanoparticles of gold in a water fluid. Colloidal gold nanoparticles usually show either an intense red or blue/purple color. Molecular sensors are generally composed of two main elements: a recognition unit, which selectively interacts with the molecule or ion to be detected, and a signaling unit that is responsible of generating a macroscopically measurable signal (optical, electrochemical, or mechanical) upon the molecular recognition event. In general, the term chemosensor is used when the binding between the receptor and the target analyte is reversible and probe, when the recognition event takes place through an irreversible chemical reaction. The transduction mechanism, which is the mechanism
