Abstract
We report the design of an electrochemical aptasensor for ampicillin detection, which is an antibiotic widely used in agriculture and considered to be a water contaminant. We studied the transducing potential of nanostructure composed of MoS2 nanosheets and conductive polypyrrole nanoparticles (PPyNPs) cast on a screen-printed electrode. Fine chemistry is developed to build the biosensors entirely based on robust covalent immobilizations of naphthoquinone as a redox marker and the aptamer. The structural and morphological properties of the nanocomposite were studied by SEM, AFM, and FT-IR. High-resolution XPS measurements demonstrated the formation of a binding between the two nanomaterials and energy transfer affording the formation of heterostructure. Cyclic voltammetry and electrochemical impedance spectroscopy were used to analyze their electrocatalytic properties. We demonstrated that the nanocomposite formed with PPyNPs and MoS2 nanosheets has electro-catalytic properties and conductivity leading to a synergetic effect on the electrochemical redox process of the redox marker. Thus, a highly sensitive redox process was obtained that could follow the recognition process between the apatamer and the target. An amperometric variation of the naphthoquinone response was obtained regarding the ampicillin concentration with a limit of detection (LOD) of 10 pg/L (0.28 pM). A high selectivity towards other contaminants was demonstrated with this biosensor and the analysis of real river water samples without any treatment showed good recovery results thanks to the antifouling properties. This biosensor can be considered a promising device for the detection of antibiotics in the environment as a point-of-use system.
Highlights
Ampicillin (AMP) is a β-lactam antibiotic widely used as a medication for bacterial infections such as pneumonia, bronchitis, and urinary tract infections [1]
The frequent use of AMP as an antibiotic has led to the emergence of multi-drug resistant (MDR) bacteria that threaten human health
A MoS2 dispersion was deposited on the screen-printed carbon electrode (SPCE) by electrochemical process
Summary
Ampicillin (AMP) is a β-lactam antibiotic widely used as a medication for bacterial infections such as pneumonia, bronchitis, and urinary tract infections [1]. It is classified as a broad-spectrum antibiotic, so its use is common in both humans and animals, resulting in the presence of residual amounts in the environment [2]. The presence of MDR bacteria has been found in treated wastewater effluents, with the most common antibiotic resistance being ampicillin (83.3%) [3] This pollution has numerous impacts on human health, such as epileptic seizures and allergic reactions [4]. Antibiotic residues can be found at higher levels in wastewater or surface waters with concentrations ranging from
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