Abstract
Penicillins and cephalosporins belong to the β-lactam antibiotic family, which accounts for more than half of the world market for antibiotics. Misuse of antibiotics harms human health and the environment. Here, we describe an easy, fast, and sensitive optical method for the sensing and discrimination of two penicillin and five cephalosporin antibiotics in buffered water at pH 7.4, using fifth-generation poly (amidoamine) (PAMAM) dendrimers and calcein, a commercially available macromolecular polyelectrolyte and a fluorescent dye, respectively. In aqueous solution at pH 7.4, the dendrimer and dye self-assemble to form a sensor that interacts with carboxylate-containing antibiotics through electrostatic interaction, monitored through changes in the dye’s spectroscopic properties. This response was captured through absorbance, fluorescence emission, and fluorescence anisotropy. The resulting data set was processed through linear discriminant analysis (LDA), a common pattern-base recognition method, for the differentiation of cephalosporins and penicillins. By pre-hydrolysis of the β-lactam rings under basic conditions, we were able to increase the charge density of the analytes, allowing us to discriminate the seven analytes at a concentration of 5 mM, with a limit of discrimination of 1 mM.
Highlights
Antibiotics are used for the treatment of human and animal diseases
We will discuss work leading to the discrimination of five cephalosporins and two penicillins whose structures are shown in Scheme 1, where the structure in red is the β-lactam ring, while green and blue stands for the core structure of cephalosporins and penicillins, respectively
Analyte solutions were prepared from terephthalic acid, benzoic acid, and ceftriaxone sodium salt hemiheptahydrate purchased from Acros (Geel, Belgium); cefazolin sodium salt and cefonicid sodium salt purchased from CHEM-IMPEX (Wood Dale, IL, USA); penicillin G sodium salt purchased from Alfa Aesar (Haverhill, MA, USA); and cephalothin, oxacillin sodium salt monohydrate, and cefotaxime sodium salt purchased from TCI (Tokyo, Japan)
Summary
Antibiotics are used for the treatment of human and animal diseases. They are added to animal feed to improve growth rates and feed efficiency [1,2,3]. The overuse of antibiotics has given rise to a number of multi-resistant bacteria, and the residues in food may cause serious allergy problems [4]. Several applications can benefit from a system that can qualitatively recognize the identity of common β-lactam antibiotics rapidly and such as testing antibiotic residues in food (for example, in milk) to prevent food allergies; measuring the type and amount of antibiotics in sewer water, to get an overall picture of antibiotic consumption in an area; and comparing the downstream and
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