A Visual Sensing Strategy Based On Self-assemble Graphene Aptamer Hydrogel For Oxytetracycline Determination

As one of the most famous and widely applied antibiotics in history, Oxytetracycline (OTC) has gradually been replaced by advanced drugs due to its severe side-effects. However, in China the situation of abusive usage of OTC still exists, especially in fishery and stockbreeding industry. Such misusage of OTC would causing serious contamination in water bodies, and might become major threat to the health of human beings. Currently, the conventional methods for detecting OTC includes HPLC and ELISA, which are well-established and sensitive. However, the time-consuming, sophisticated handling and the requirement of advanced instruments would inevitably restricted their applications in rapid sensing. To achieve swift and straightforward detection of OTC, innovative materials and techniques are required.Herein, we have established a visual sensing method for detecting OTC based on synthesizing a self-assemble graphenc-aptamer hydrogel. A novel bio-chemical hydrogel crosslinked through non-covalent effect has been produced, utilizing unique chemical properties and bio-friendly characteristics of graphene and outstanding selectivity and strong combination of aptamer. SEM, XRD and Raman Spectrum were measured in order to explore the inner structure of the hydrogel. By balancing the concentration ration between graphene and aptamer during synthesis, we optimized detection capability of the hydrogel. Finally, the qualitative and quantitative detection of OTC were accomplished through measuring UV absorption of the solutions.By detecting different OTC samples and characterizing such graphene-aptamer hydrogel, the feasibility of our hydrogel based visual sensing platform is verified. By balancing the concentration ratio between aptamer and graphene oxide, together with optimizing the parameters during synthesize, the detection performance of the platform is improved. The detection range of our technique to OTC could reach to 50 μg/L, meanwhile, this method had presented its outstanding selectivity against similar antibiotics such as Minocydine, Isochlortetracycline, Sulfamethoxazole and Erythromycin.Additionally, to further explore the potential in sensing and detecting, we managed to encapsulate Rhodamine B molecule into the structure of the hydrogel, and verified the sensing capability of the hydrogel. This research has achieved high selective and sensitive visual sensing of OTC, through constructing a self-assemble graphene-aptamer hydrogel. We assume such design could help to provide new insights for establishing a rapid and straightforward visual sensing platform.