Nanoparticles have been studied in agriculture for their potential to mitigate abiotic stress in crops. Here, the use of manganese nanoparticles to increase stress tolerance in Raphanus sativus was investigated. Few studies have been conducted on the synthesis and uses of manganese nanoparticles. This study was among the first to synthesize manganese nanoparticles using a microfluidic device. Fluorescence spectroscopy and scanning electron microscopy were used to confirm that the particles synthesized were in the nanoscale size range. When foliarly applied to R. sativus that had been exposed to stress, the nanoparticles significantly increased growth rate, indicating an increase in stress tolerance. In addition, several other capping ligands were used for the manganese nanoparticles. FusionRed protein was expressed and purified in Escherichia coli. This protein, along with a Texas-Red labeled BSA protein, were successfully used as capping ligands for the manganese nanoparticles. [ABSTRACT FROM AUTHOR]