Applications Of An Electrochemical Sensor Based On Surface-treated Escherichia Coli For Toxic Measurements Sensors

Objective The discharged industrial wastewaters with pharmaceutical intermediates not only induce environmental pollution but also effect human health directly because pollutants could be magnified along the food chains, Therefore, it is urgent to establish a method for monitoring and measuring the wastewaters and suspected pharmaceutical intermediates. Therefore, a rapid and sensitive electrochemical technology was constructed based on surface-treated Escherichia coli(E. coli) by Triton X-100.Methods The activities of surface-treated E. coli by Triton X-100 and sensitivity of treated E. coli to toxicities of toxins were investigated by introducing K3Fe(CN)6as a mediator to measuring changes of reduced productions of ferricyanide. Moreover, the results of scanning electron microscopy(SEM) and the growth curves were used to estimate the changes of morphology and reproductive ability of surface-treated E. coli. Then, the treated cells were used to monitor toxic measurements of 4-nitriphenol(4-NP) and wastewater samples.Results The results of electrochemical analysis revealed that the electrochemical signals based on activities of E. coli were maximum while concentrations andincubation times of Triton X-100 on E. coli were 2% and 1 h. But increase of exposed times, activities of E. coli were degenerated even worse than untreated E. coli when the incubation time was 4 h. The results of SEM proved that the more permeability of E. coli was harvested when the cells were treated 2% Triton X-100 at 1 h incubation time. Furthermore, results of growth curves test were used to investigate the effects of 2% Triton X-100 on the E. coli cells at 1 h incubation times. The results showed that 2% Triton X-100 at 1 h incubation time just affected the parent of E. coli cells. No obvious effects of Triton X-100 appeared on offspring of treated cells. Then the cells treated by 2% Triton X-100 at 1 h incubation time were chosen to determine the toxicities of 3,5-dichlorophenol(DCP). The 50% inhibiting concentration(IC50) of DCP on treated cells was 6.60 mg·L-1, while 6.60 mg·L-1 DCP solution on untreated cells just showed 34.4% inhibition. The 4-NP as a pharmaceutical intermediate was detected by our electrochemical biosensor. The IC50 of 4-NP on treated cells and untreated cells were 15.3 mg·L-1 and 17.7 mg·L-1, respectively. Moreover, seven water samples were detected, and ranges of inhibition rate on treated cells and untreated cells were 4.37%~5.90% and 2.24%~3.69%.Conclusions To constructed an electrochemical biosensor based on surface-treated E. coli for toxic measurements of 4-NP an water samples. The treated conditions were optimized with the anticipation of our investigations, surface-treated E. coli by 2% Triton X-100 at 1 h incubation time showed the more active and sensitive than untreated cells. It means that our investigation provides a good alternative for monitoring toxicities of pharmaceutical intermediates and discharged wastewaters.