Label-free detection of endotoxin and gram-negative bacteria from water using copper (I) oxide anchored reduced graphene oxide

Bacterial contamination is a serious concern for health and environmental safety. The major toxic effect arises from the endotoxin or lipopolysaccharide (LPS) attached to the cell wall of the gram-negative bacteria. Ultrasensitive endotoxin detection is of supreme importance in sustaining food, clinical and pharmaceutical safety. Herein we report a simple electrochemical detection platform using reduced graphene oxide (rGO) combined with cuprous oxide nanoparticles for the ultrasensitive detection of LPS. The sensor uses polymyxin B (PmB) to achieve the selective response towards LPS. The sensor showed a lower detection limit (LOD) of 10 agmL-1 with linearity from 10 agmL-1 to 10 ngmL-1. Detection of LPS from whole blood is also carried out with excellent sensitivity. The sensor showed excellent recovery rates in whole blood, pointing to the capability of using the sensor in real-life clinical analysis. The sensor detects Gram-negative bacteria from sewage water with a rapid response time, indicating the effectiveness of the sensor in water quality analysis.