Over the years, nanotechnology has proved its worth in many fields of sciences including biology. It is an emerging field that takes advantage of the properties of nanoparticles to perform various functions ranging from disease detection to its role in providing superior quality agriculture and food products. Different types of nanoparticles have different applications, like fluorescent nanoparticles are used for imaging or labelling molecules in biological systems. Gold and silver nanoparticles are used in nano-sensors to detect pathogens. Nano-sensors have bioreceptors like immunoglobulins, nucleic acid and many other biological molecules, to recognize the target molecules. On the basis of these bioreceptors, nano-sensors can be divided into immunosensors, genosensors, enzyme-based and Whole-cell-based nano-sensors. These are highly specific and sensitive in nature and different methods of signal transduction like optical and electrochemical makes them more efficient. These sensors can be fabricated by methods like lithography which is used to form patterns at nanoscale level on a surface. Nanoparticles then self-assemble spontaneously by specific interactions or can be assembled by 3D printing. So far nano-sensors have been used for early detection of many microbes like Brucella and Clostridium etc. This high sensitivity and specificity of nanotechnology will pave the way for development of better disease diagnostic tools in near future.