Highly sensitive and selective serotonin (5-HT) electrochemical sensor based on ultrafine Fe3O4 nanoparticles anchored on carbon spheres.

Neurotransmitter serotonin (5-HT) is involved in various physiological and pathological processes. Therefore, its highly sensitive and selective detection in human serum is of great significance for early diagnosis of disease. In this work, employing iron phthalocyanine as Fe source, ultrafine Fe3O4 nanoparticles anchored on carbon spheres (Fe3O4/CSs) have been prepared, which exhibits an excellent electrochemical sensing performance toward 5-HT. With carbonecous spheres turned into conductive carbon spheres under the heat treatment in N2 atmosphere, iron phthalocyanine absorbed on their surfaces are simultaneously pyrolysised and oxidized, and finally transformed into ultrafine Fe3O4 nanoparticles. Electrochemical results demonstrate a high sensitivity (5.503 μA μM-1) and a low detection limit (4 nM) toward 5-HT for as-prepared Fe3O4/CSs. In combination with the morphology and physicochemical property of Fe3O4/CSs, the enhanced sensing mechanism toward 5-HT is disscussed. In addition, the developed electrochemical sensor also displays a good sensing stability and an anti-interferent ability. Further applied in real human serum samples, a satisfactory recovery rate is achieved. Promisingly, the developed electrochemical sensor can be employed for the determination of 5-HT in actual samples.