Controlled molecular architectures in microfluidic immunosensors for detecting Staphylococcus aureus

Author(s)

Soares, Andrey Coatrini ^[1] ; Soares, Juliana Coatrini ^[1] ; Rodrigues, Valquiria Cruz ^[2] ; Oliveira, Jr., Osvaldo N. ^[2] ; Capparelli Mattoso, Luiz Henrique ^[1]

Affiliation

^[1] Embrapa Instrumentacao, Nanotechnol Natl Lab Agr LNNA, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Sao Carlos Inst Phys, BR-13566590 Sao Carlos - Brazil

• Document type: Journal article
• Source: ANALYST; v. 145, n. 18, p. 6014-6023, SEP 21 2020.
• Web of Science Citations: 1

Abstract

Detection of pathogenic microorganisms is essential for food quality control and diagnosis of various diseases, which is currently performed with high-cost, sophisticated methods. In this paper, we report on a low-cost detection method based on impedance spectroscopy to detect Staphylococcus aureus (S. aureus). The immunosensors were made with microfluidic devices made of interdigitated electrodes coated with layer-by-layer (LbL) films of chitosan and chondroitin sulfate, on which a layer of anti-S. aureus antibodies was adsorbed. The limit of detection was 2.83 CFU mL(-1) with a limit of quantification of 9.42 CFU mL(-1) for immunosensors with 10-bilayer LbL films. This level of sensitivity is sufficient to detect traces of bacteria that cause mastitis in milk, which we have confirmed by distinguishing milk samples containing various concentrations of S. aureus from pure milk and milk contaminated with Escherichia coli (E. coli) and Salmonella. Distinction of these samples was made possible by projecting the electrical impedance data with the interactive document mapping (IDMAP) technique. The high sensitivity and selectivity are attributed to the highly specific interaction with anti-S. aureus antibodies captured with polarization-modulated reflection absorption spectroscopy (PM-IRRAS), with adsorption on the antibodies explained with the Langmuir-Freundlich model. Since these immunosensors are stable for up to 25 days and detection measurements can be made within minutes, the methodology proposed is promising for monitoring S. aureus contamination in the food industry and hospitals, and in detecting bovine mastitis. (AU)

• FAPESP's process: 18/18953-8 - Nanostructured films applied in microfluidic biosensors to mastitis detection
• Grantee: Andrey Coatrini Soares
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/22214-6 - Towards a convergence of technologies: from sensing and biosensing to information visualization and machine learning for data analysis in clinical diagnosis
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants