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Abstract

The application of nanotechnology in the field of regenerative medicine has opened a new realm of advancement in this field and has provided hope for the culmination of long-felt needs by the development of an ideal means to control the biochemical and mechanical microenvironment for successful cell delivery and tissue regeneration. Nanotechnology aims to create and use structures and systems in the size range of approximately 1-500 nm. Nanomaterials used in regenerative medicine are majorly fabricated using one or more of the following approaches. Bottom-up approaches use nanotechnology as a strong tool for synthesis of novel materials that behave differently in bulk compared with their nanoscale versions. Such materials include polymeric and inorganic nanoparticles, self-assembled materials, carbon nanotubes (CNTs), dendrimers, quantum dots (QDs), layer-by-layer (LbL) structures and so on [1] . Since the cellular response to nanoscaled patterns may precisely direct formation of appropriate functional tissue, it is generally required that biomimetic delivery matrices be designed to have structural similarity to native tissue in a nanoscale range [2] . Hence, top-down approaches involve nanoscale modifications of existing polymers and materials and are used to fabricate nanoengineered systems, such as nanopatterned substrates to provide structures that influence cell behavior and subsequent tissue formation. Nie and Kumacheva have reviewed current surface patterning approaches for cell biology, tissue engineering and medicinal science [3] . Figure 1 gives an illustration of various nanotechnology approaches used in regenerative medicine. In particular, nanotechnology has been employed to overcome some of the limitations associated with the current regeneration strategies, including both therapeutic and diagnostic approaches. The major applications of various nanomaterials currently being used in regenerative medicine and related biomedical applications include their use as: * Scaffolds for cell growth; * Delivery devices for various drugs, growth factors and genes; * Applications for cellular modification, isolation and tracking; * Nanodevices, such as biosensors (Table 1). A few of them are currently being investigated in clinical trials or in the market and have been listed in Table 2. The current review elaborates various nanomaterials used in regenerative medicine and the recent advances in their aforementioned applications with a special focus on the developments in this field during the last 5 years. Furthermore, the key issues and challenges in using nanotechnology-based approaches are highlighted with an outlook on the likely future of nano-assisted regenerative medicine.