To find new and better ways to detect and monitor contamination of water, food and the environment as early as possible directly at the site of impact is one of the most pressing tasks for researchers today. Early detection of and strategic monitoring to trace contamination of water is therefore crucial. This emphasizes the need for sensitive, robust, portable and affordable (especially for low-income countries) analysis tools that can report directly at site on the concentration of a target contaminant. Detecting contamination early means that these small, mobile analytical devices must indicate analytes at very low concentrations with reliable uncertainty and accuracy, to avoid false positives and foster acceptance of such tools by relevant user groups like public employees. In this project, attempts were made to address these problems by relying on the integration of gated delivery systems, magnetic beads, fluorescence spectroscopy and electrochemiluminescence (ECL) detection. ECL is a detection method that operates against a zero background while fluorescence spectroscopy provides highly sensitive detection. In addition, gated delivery systems exhibit inherent features of signal amplification. Silica nanoparticle based gated dye delivery systems were successfully developed for the detection of toxic heavy metal ions such as Hg2+ as well as organophosphate pesticide chlorpyrifos. These systems could detect the analytes at trace levels. A combination of these strategies with the versatile handling and miniaturization capabilities of microfluidics has the potential to yield user-friendly, affordable and robust analytical devices with unprecedented performance for the reliable quantification of analytes at ultra-trace levels directly on-site at the point- of-need.
