Stable Competitive Enzyme-Linked Immunosorbent Assay Kit for Rapid Measurement of 11 Active Beta-Lactams in Milk, Tissue, Urine, and Serum

Abstract

Beta-lactams are used as veterinary drugs for the treatment of food-producing animals. For consumer protection, legislation is in place to set limits for their residues. An enzyme-linked immunosorbent assay (ELISA) was developed which allowed, in a single reaction, the class-specific measurement of 11 beta-lactams, with limits of detection below European maximum residue limits. Determinations were feasible in milk, tissue, urine, and serum with simple and rapid sample preparation. In this format, the specific capture antibodies were precoated on the microtiter plate and horseradish peroxidase-labeled conjugate was used to compete with free beta-lactams. The stability of the precoated microtiter plate and conjugate was at least 1 year when stored at 2 to 8°C; upon reconstitution, the conjugate was stable for 6 days at 2 to 8°C. The stability of lyophilized ampicillin standards was at least 6 months when stored at 2 to 8°C and at least 1 year when stored at 20°C. A low cross-reactivity, 3.6%, was observed with ampicillin with open beta-lactam ring relative to 100% for intact ampicillin. Generic recognition was shown by relative cross-reactivity values ranging from 22 (penicillin V) to 144% (nafcillin). Cross-reactivity for cephalosporins was <0.1%. Intra- and interassay precisions expressed as coefficient of variation were typically 2-8%. The inhibitory concentration with 50% binding for ampicillin was typically 2 ppb. Recovery for different spiked levels was >70% with all the matrixes.

Characterizing aptamer small molecule interactions with backscattering interferometry

“…The three other SM targets studied here represent species that are relatively difficult to measure, most typically by ELISA requiring multiple binding and wash steps. [42][43][44] In this case, the mix-and-read operation by BSI is particularly advantageous because it allowed rapid K d range nding, on constrained sample quantities (microliter volumes), with no a priori information about the species.…”

An aptasensor for ampicillin detection in milk by fluorescence resonance energy transfer between upconversion nanoparticles and Au nanoparticles

“…Presently, several methods have been used for antibiotics detection in food, such as high-performance liquid chromatography (HPLC) ( Luo, Ang, & Thompson Jr, 1997 ), enzyme-linked immunosorbent assay (ELISA) ( FitzGerald, O’Loan, McConnell, Benchikh, & Kane, 2007 ), and electrochemistry ( Li, Zhu, Li, Liu, Li, & Kang, 2020 ), etc. However, expensive instruments and professional users are required to implement the analysis work, making them unable for a large number of detection tasks.…”

Conjugation of ampicillin and enrofloxacin residues with bovine serum albumin and raising of polyclonal antibodies against them

“…They are also being used as growth promoters and prophylactic agents in lactating animals which is responsible for the presence of their residues in the milk [ 1 ]. Beta-lactam antibiotics like penicillin are the most frequently used, the residues of which can produce detrimental effects such as allergic reactions in humans who are sensitive to beta-lactams [ 2 ]. It may also lead to the development of antibiotic-resistant strains of bacteria [ 3 ].…”