Reduced Graphene Oxide Quantum Dots-Anchored Biopolymer Composite as Smart Sensor Platform for Fluorescent and Electrical Sensing of Rifampicin

Rifampicin (RFP), also known as rifampin, is an antibiotic medication used to treat tuberculosis and pathogenic bacterial infections. However, improper use typically results in severe side effects, bacterial resistance, and drug-induced environmental pollution. Therefore, the fabrication of an efficient sensor for RFP is of great concern. In this study, a green synthesis approach is implemented to develop a sensor using reduced graphene oxide quantum dots (rGQDs). Their photoluminescence properties are utilized to construct an optical sensor for the detection of RFP. The sensor operates through a Forster resonance energy transfer (FRET)-based quenching mechanism, which inspires us to fabricate a mobile phone-assisted smart sensor system. In this portable device, the rGQD-anchored biopolymer-coated cellulose-based flexible substrate is used as a multimode sensor that can simultaneously process electrical and fluorescence responses in the presence of RFP. The practical applicability of the sensor system was tested in three different real samples, such as human blood serum, human urine, and tap water. The corresponding limit of detection (LOD) was evaluated by the standard calibration method and found to be 81.36, 79.94, and 74.35 nM, respectively. On the other hand, electrical and fluorescence smart sensing results show a sensitive response where the LOD is found to be 2.16 and 11.36 μM, respectively. This sensor possesses the special advantage of being portable, rapid, and selective toward RFP only. The multimode sensing strategy eliminates the time-consuming fabrication process. Moreover, the recyclability issue can be resolved by using this low-cost bridgeable material, which is readily available and demanding in terms of e-waste environmental pollution.