This book provides a comprehensive overview on the most important types of nanosensor platforms explored and developed in the recent years for efficient detection of environmental/clinical analytes. The chapters cover basic aspects of functioning principles and describe the technologies and challenges of present and future pesticide, metal ions, toxic gases analytical sensing approaches and environmental sensors. Nanosensors are nanoscale miniature devices used for sensing of analyte in ultra-low range. These have gained considerable interest in environmental applications such as environmental chemistry and functionalization approaches, environmental engineering, sustainability, green technology for sensing, environmental health monitoring, pesticide detection, metal and ions detection using electrochemical and wireless sensor.