Polystyrene nanofibers capped with copper nanoparticles for selective extraction of glutathione prior to its determination by HPLC.

Polystyrene nanofibers were coated with copper nanoparticles (CuNPs) by a combination of electrospinning and in-situ reduction of Cu(II) using sodium borohydride as the reductant. The CuNPs on the nanofibers were characterized by energy dispersive spectrometry, scanning electron microscopy and transmission electron microscopy. A cartridge was packed with the nanofibers which then were activated with methanol and water. Glutathione (GSH) is found to quantitatively adsorbed by the packed cartridge at pH 3.0, and then can be desorbed with aqueous 2-mercaptoethanol and detected, after derivatization with ortho-phthalaldehyde, via high performance liquid chromatography with fluorometric detection. Under optimized conditions, the method has a 1.1 ng·mL-1 detection limit and a response that is linear in the 10-1000 ng·mL-1 GSH concentration range. The recoveries of GSH from artificial urine spiked at three levels (80, 400 and 800 ng·mL-1) are in the range of 94.6-98.6% with relative standard deviations (RSD) of <4.5% (n = 5). The method was applied to assessing the differences in urinary GSH between high-risk infants and healthy infants. The results show that the levels of GSH of normal infants are significantly higher than those of high-risk infants (P < 0.05). Graphical abstract Schematic of the preparation of CuNP-assembled nanofibers and the mechanism of extracting glutathione (GSH). GSH can be extracted by this material based on a strong interaction between the sorbent and GSH. This is attributed to the formation of Cu-S bonds between Cu and -SH.