Produção e validação de um biosensor para detecção do antigénio STn associado a cancro

O cancro está frequentemente associado à biosíntese de estruturas aberrantes, incluindo a sintese de STn. O nosso trabalho demonstra a eficácia de uma lectina, Sambucus nigra, como elemento de reconhecimento de STn. Acoplada a um biosensor demonstrou ser uma estratégia eficaz para discriminar entre soros de individuos saudáveis e indivíduos com cancro.

Autores e Afiliações:

Silva ML_¹, Gutiérrez E_², Rodríguez JA_², Gomes C_³, David L_⁴

1Centre of Chemical Research, Autonomous University of Hidalgo State, Mexico

2Centre of Chemical Research, Autonomous University of Hidalgo State, Mexico

3Institute of Molecular Pathology and Immunology of the University of Porto - IPATIMUP, Portugal.

4Institute of Molecular Pathology and Immunology of the University of Porto - IPATIMUP, Portugal; Medical Faculty of the University of Porto, Portugal.

Abstract:

A label-free electrochemical impedance spectroscopy biosensor for selective detection and discrimination of the cancer-associated sialyl-Tn (STn) antigen was developed by using Sambucus nigra agglutinin type I (SNA-I) as the recognition element. The SNA-I biosensor was constructed by immobilizing the lectin on screen-printed gold electrodes. The formation of a complex between SNA-I and STn-containing glycoproteins (transferrin and bovine submaxillary mucin) was monitored by measuring the impedance increase of the biosensor. The increase in electron transfer resistance was linearly proportional to the concentration of the glycoproteins up to 70ng of transferrin and 40ng of bovine submaxillary mucin, with a limit of detection of 20ng for transferrin. Albumin, the most abundant serum protein, did not interfere in the detection of the STn-glycoproteins up to a concentration of 0.2mgml^-1. The developed lectin-based biosensor was used to evaluate the STn-expression in serum samples and discriminate samples from healthy individuals and patients with different types of malignant tumors, mostly carcinomas, where the increased expression of STn aberrant glycans is well established. This work demonstrates the feasibility of employing SNA-I to selectively recognize the STn epitope in glycoproteins and the use of the constructed biosensor was effective in the analysis of serum samples with the ability to discriminate in a fast way between cancer and healthy status. The proposed biosensor could be used for high-throughput, label-free profiling of the cancer-associated STn glycan expression in serum for diagnosis and therapy monitoring.