Prova de conceito do uso da Plataforma BioSearch para a detecção de resíduos de benzilpenicilina no leite

Abstract

Milk is a food of high nutritional value and great economic and social importance in Brazil. However, residues of antimicrobials, such as benzylpenicillin, may be present in milk as a result of therapeutic use in lactating cows, especially when there are failures to comply with the withdrawal period, representing risks to public health, losses to the industry, and significant economic losses for the rural producer. To minimize these effects, the detection of antimicrobial residues is regulated by official agencies and commonly performed using sensitive confirmatory tests. Nevertheless, these tests are expensive and not suitable for routine use. As an alternative, screening tests, widely used by producers, enable faster and more cost-effective preliminary detection, although they present limitations in reproducibility and interpretation. Evomilk, a company in the dairy sector, identified the need for more reliable and accessible alternative screening methods for antimicrobial monitoring, which motivated the development of this project. In this context, and in collaboration with Evomilk, this study aimed to demonstrate the proof of concept of the BioSearch Platform for the detection of benzylpenicillin in milk. The platform represents an innovative Brazilian technology based on depolarized dynamic light scattering (D-DLS), employing optical biosensors capable of detecting interactions between analytes and antibodies without the need for secondary markers, thus allowing rapid and in situ measurements. For this purpose, biosensors composed of gold nanorods functionalized with monoclonal IgG anti-penicillin antibodies were developed, capable of recognizing the β-lactam ring of benzylpenicillin. Initial tests performed in reconstituted Difco Skim Milk Powder demonstrated good reproducibility, selectivity and sensitivity for detecting low ppm levels of benzylpenicillin in less than ten minutes. These results indicate that the technology has strong potential to be used as a screening test in farms and cooperatives, enabling the identification of contaminated milk before it reaches dairy plants. Future studies will focus on testing milk samples collected directly from dairies, validation, and improving sensitivity to reach regulatory limits (a few ppb).