Detection of Salmonella enterica on silicon substrates biofunctionalized with anti-Salmonella IgG, analyzed by FTIR spectroscopy

Salmonella enterica was detected at a concentration of 500 CFU/mL. For this, three substrates were used (crystalline and amorphous silicon, hydrogenated amorphous silicon carbide) with an area of 25 mm², functionalized by the self-assembled monolayers (SAM) technique. Characteristic functional groups of SAMs were observed (-NH₂, -C=O, Si-O-Si, Amide I, Amide II) by the Fourier transform infrared spectroscopy (FTIR) technique. Anti-Salmonella IgG antibodies were generated. To determine the secondary structure of proteins, second derivative of each FTIR detection spectrum was generated, observing modifications in the zone between 1600-1700 cm^-1, which corresponds to the region of proteins, specifically to structures of β- sheets and β-turns, as a result, substrates or platforms of crystalline silicon and hydrogenated amorphous silicon carbide showed band frequencies with higher intensity, being this attributed to a better sensitivity, which are proposed for applications in the development of biosensors for the monitoring of microbial quality in foods.