Smart Paper-Based Nanosensor for Simultaneous Environmental eMonitoring of Nitrate and Nitrite

Area of Science:

• Environmental Science
• Analytical Chemistry
• Nanotechnology

Background:

• Nitrate and nitrite contamination from agricultural and industrial sources threaten public health and the environment.
• Current detection methods are often complex, time-consuming, and require specialized equipment, hindering field applicability.

Purpose of the Study:

• To develop a portable, IoT-integrated, paper-based fluorescent sensor for sensitive and simultaneous detection of nitrate (NO3-) and nitrite (NO2-).
• To create a device meeting WHO's REASSURED criteria for ideal sensing technologies.

Main Methods:

• Utilized phenylene-diamine-derived carbon quantum dots (CQDs) as fluorescent probes.
• Implemented an on-strip reduction method to convert nitrate to nitrite for unified detection.
• Integrated the sensor with a hand-held optoelectronic reader and smartphone interface for real-time data analysis and wireless transmission.

Main Results:

• Achieved a limit of detection (LOD) of 0.1 ppm for both analytes.
• Demonstrated a linear response range from 1 to 100 ppm.
• Validated the sensor's performance using real water samples, accurately quantifying nitrate and nitrite concentrations.

Conclusions:

• The developed sensor provides a green, low-cost, and efficient solution for on-site environmental monitoring.
• The integration of nanotechnology, paper-based analytical devices, and smart sensing enables rapid decision-making for water quality assessment.