*Corresponding author email: sanjay.singh@ahduni.edu.in Symbiosis Group Symbiosis www.symbiosisonline.org www.symbiosisonlinepublishing.com Catalytically Active Nanomaterials: Artificial Enzymes of Next Generation Sanjay Singh* Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Central Campus, Navrangpura, Ahmedabad 380009, Gujarat, India Nanoscience & Technology: Open Access Open Access Research article Introduction Natural enzymes are extremely specific and efficient biocatalysts, facilitating almost every biochemical process in living organisms with rapid rate (10 19 times) of reaction [1]. Although the location and function of natural enzymes are well orchestrated, their practical utility is often compromised by some of their intrinsic hitches. These drawbacks could be the high cost of production, purification and storage, lower stability in extreme physiological conditions, lower recyclability, and the stringent requirement for optimum catalytic activity [2-4]. In this context, next-generation artificial enzymes are needed. Recent developments in nanotechnology have led to the generation of nanomaterials exhibiting the catalytic activities analogous to natural enzymes [5-10]. These catalytically active nanoparticles (nanozymes) seem to solve the issues related to natural enzymes, Abstract Due to the inherent limitations associated with natural enzymes, discovery and development of nanomaterials-based artificial enzymes (nanozymes) are highly desired. These nanozymes may address the issues with practical applications of natural enzymes such as high cost of synthesis, purification, storage and limited spectrum of catalytic activity. In this review article, a crisp description of the recent progress in exploring, bio catalytic activity and constructing nanozymes, including AuNPs, carbon-based nanomaterials, and CeO 2 NPs are discussed. A brief description of new or enhanced applications of these nanozymes in bio diagnosis and therapeutics has also been provided. Additionally, a section is dedicated to the use of efficient modulators of nanozymes to improve the catalytic performance. Nanozymes exhibiting multi-enzyme activity such as core-shell of Au and CeO 2 NPs, carbon-based nanomaterials, and Au and SiO 2 NPs is also discussed in detail. Based on the recent investigations reported by our group and others, it is expected that nanozymes containing unique and tunable properties and functions will attract tremendous research interest and generate novel opportunities in several avenues of biomedicines. Keywords: Gold Nanoparticles; Cerium oxide; Peroxidase activity; Oxidase activity; Superoxide dismutase activity; Nanozymes Received: November 17, 2017; Accepted: December 5, 2017; Published: December 10, 2017 *Corresponding author: Sanjay Singh, Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Central Campus, Navrangpura, Ahmedabad - 380009, Gujarat, India. Tel: +91-79-61911270. E-mail: sanjay.singh@ahduni.edu.in as they offer low cost of production, size, and shape mediated control over catalytic activity and high stability in extreme physiological conditions. Utilizing the enzymatic properties of these nanozymes, several detection methods of analytes in extremely low concentration has also been devised [7, 11-14]. Considering the above-mentioned advantages of nanozymes, in this review article, we comprehensively discuss the recent developments and future direction of nanomaterials as artificial enzymes. Recent utilization of enzymes in the construction of biosensors, food industry, technological applications and agricultural research has seen prompt progress. Although several natural enzyme-based methods have been devised in these areas, however, the realization of actual potential has been not received due to the limitations associated with enzymes. In this context, merging nanotechnology with enzymology has paved a way to design novel multifunctional nanozymes exhibiting intrinsic biological enzyme-like activities. So far several types of nanomaterials such as gold (Au), Silver (Ag), Copper (Cu) nanoparticles (NPs), Cerium oxide (CeO 2 ), iron oxide, V 2 O 5 , Pt, Pd, graphene, fullerenes, and carbon nano tubes etc [7,15-24]. have been investigated to possess the natural enzyme-like activities. Oxidase, peroxidase, superoxide dismutase (SOD) and catalase are some of the most studied enzymes for which nanomaterials- based artificial enzymes have been investigated (Figure 1). Despite the vast variety of nanomaterials exhibiting enzyme-like activities, this review will only focus on the nanozymatic activity of gold nanoparticles. Since during last two decades, CeO 2 NPs and certain carbon based materials have emerged as potential antioxidants which have shown tremendous applications in treating oxidative stress based human diseases, towards the end of this review article, a short report will be provided on CeO 2 NPs and carbon-based nanomaterials. Among metallic nanomaterials, AuNPs have been well explored for their enzyme-like activities. Such investigation becomes more intense as AuNPs offers high biocompatibility to