LAUSR

It is of great significance to realize the detection of trace amounts of superoxide anions (O2•-) in biological systems due to the connection between the concentration of O2•- and some diseases. Here, we present a novel method to fabricate a non-enzymatic electrochemical sensor for measuring O2•- from biological systems. The sensor was fabricated by nanocomposites (PAMAM-Au) synthesized by using (PAMAM-G4.0) dendrimers as template/stabilizers for gold nanoparticles (AuNPs) growth. Transmission electron microscopy (TEM) investigations indicate that AuNPs were encapsulated in PAMAM with average diameter about 8 nm. The electrochemical technique confirmed that PAMAM-Au possessed extraordinary electrochemical response to superoxide anions. As an analytical and sensing platform, apart from excellent sensitivity, wide liner range (from 3.69 × 10-5 - 37.2 μM), ultra-low detection limit (0.0123 nM), our sensor also presented satisfying performance for monitoring changes of O2•- levels upon different stimuli. Furthermore, we investigated the effect of temperature on superoxide anions released from living cells and enzyme activity through an electrochemical method for the first time. Most importantly, the simulated electrochemical study in vitro further confirmed that temperature has a crucial influence on both the ability of living cells to resist external stimulation and the antioxidant capacity of superoxide dismutase. As expected, the study may provide researchers with potential value for understanding the temperature effects on organisms and the treatment of diseases caused by oxidative stress.