Lateral flow assay applied to pesticides detection: recent trends and progress.

Devices based on lateral flow assay (LFA) have been gaining more and more space in the detection market mainly due to their simplicity, speed, and low cost. These devices have excellent sensing format versatility and make these strips an ideal choice for field applications. The COVID-19 pandemic boosted the democratization of this method as a "point of care testing" (POCT), and the trend is that these devices become protagonists for the monitoring of pesticides in the environment. However, designing LFA devices for detecting and monitoring pesticides in the environment is still a challenge. This is because analytes are small molecules and have only one antigenic determinant, which makes it difficult to apply direct immunoassays. Furthermore, most LFA devices provide only qualitative or semi-quantitative results and have a limited number of applications in multi-residue analysis. Here, we present the state of the art on the use of LFA in the environmental monitoring of pesticides. Based on well-documented results, we review all available LFA formats and strategies for pesticide detection, which may have important implications for the future of monitoring pesticides in the environment. The main advances, challenges, and perspectives of these devices for a direction in this field of study are also presented.

Impact of conjugation strategies for targeting of antibodies in gold nanoparticles for ultrasensitive detection of 17ß-estradiol.

Antibody-coated nanoparticles have recently attracted considerable attention, with the focus falling on diagnostics. Nevertheless, controlled antibody bioconjugation remains a challenge. Here, we present two strategies of bioconjugation with the aim of evaluating the best approach for the coupling of antibodies on the surface of nanomaterials in an oriented way. We employed electrostatic interaction (physical adsorption) and covalent conjugation in the orientation of antibodies on the metallic surface as coupling methods, and their influence on the detection of 17ß-estradiol was addressed with localized surface plasmon resonance. The understanding of these mechanisms is fundamental for the development of reproducible inorganic bioconjugates with oriented surface as well sensibility of immunoassays.

Desenvolvimento e validação de método analítico para análise de 2,4-D, 2,4-DCP e 2,4,5-T para monitoramento em água de abastecimento público / Development and validation of analytical method for analysis of 2,4-D, 2,4-DCP and 2,4,5-T for monitoring of public water supply

RESUMO O ácido 2,4-diclorofenoxiacético (2,4-D) é o segundo herbicida mais consumido no Brasil e seus efeitos na contaminação dos recursos hídricos e consequente risco sanitário para abastecimento público são conhecidos. O 2,4-D e seu principal produto de degradação, o 2,4-diclorofenol (2,4-DCP), apresentam potencial de desregulação endócrina, e o ácido 2,4,5-triclorofenoxiacético (2,4,5-T) é tóxico e persistente no meio ambiente. A inexistência de uma metodologia para quantificação simultânea desses compostos motivou o desenvolvimento e a validação do método de extração e concentração de amostras ambientais e a quantificação em cromatografia líquida de alta eficiência com detector de arranjo de diodos (CLAE-DAD) para análise de 2,4-D, 2,4-DCP e 2,4,5-T em água filtrada produzida em estação de tratamento de água e água de manancial superficial. Os resultados de extração em fase sólida e a concentração da amostra demonstraram recuperação de 89 a 119%, e desvio padrão entre 0,9 e 11,4%. Para os ensaios de identificação e quantificação, os limites de detecção variaram entre 0,17 e 0,51 µg.L-1 e limite de quantificação de 1,0 µg.L-1. Os resultados mostraram que é possível empregar esse método na quantificação do 2,4-D, do 2,4-DCP e do 2,4,5-T em monitoramento ambiental e em sistemas de abastecimento de água atendendo às legislações brasileiras.

ABSTRACT The 2,4-dichlorophenoxyacetic acid (2,4-D) is the second most consumed herbicide in Brazil and their effects in the contamination of the water resources and consequent sanitary risk for public supply are known. The 2,4-D and its main degradation product, 2,4-dichlorophenol (2,4-DCP), have the potential for endocrine disruption and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) is toxic and persistent in the environment. The absence of a methodology that simultaneously determines these compounds led to the development and validation of the solid phase extraction method, environmental samples concentrations, identification and quantification in HPLC-DAD for 2,4-D, 2,4-DCP and 2,4,5-T analysisin filtered water, produced at water treatment plants, and surface water. The extraction essay and samples concentration showed recovery from 85 to 119%, standard deviation between 0.9 and 11.4%. For identification and quantification essays, detection limits ranged between 0.17 and 0.51 µg.L-1 and the quantification limit was 1.0 µg.L-1. The results showed that it is possible to employ this method for the quantification of 2,4-D, 2,4-DCP and 2,4,5-T in environmental monitoring and in water supply systems taking account of Brazilian regulatory agencies