Versatile design and synthesis of nano-barcodes.

Encoded nano-structures/particles have been used for barcoding and are in great demand for the simultaneous analysis of multiple targets. Due to their nanoscale dimension(s), nano-barcodes have been implemented favourably for bioimaging, in addition to their security and multiplex bioassay application. In designing nano-barcodes for a specific application, encoding techniques, synthesis strategies, and decoding techniques need to be considered. The encoding techniques to generate unique multiple codes for nano-barcodes are based on certain encoding elements including optical (fluorescent and non-fluorescent), graphical, magnetic, and phase change properties of nanoparticles or their different shapes and sizes. These encoding elements can generally be embedded inside, decorated on the surface of nanostructures or self-assembled to prepare the nano-barcodes. The decoding techniques for each encoding technique are different and need to be suitable for the desired applications. This review will provide a thorough discussion on designing nano-barcodes, focusing on the encoding techniques, synthesis methods, and decoding for applications including bio-detection, imaging, and anti-counterfeiting. Additionally, associated challenges in the field and potential solutions will also be discussed. We believe that a comprehensive understanding on this topic could significantly contribute towards the advancement of nano-barcodes for a broad spectrum of applications.