Optimization and characterization of a homogeneous carboxylic surface functionalization for silicon-based biosensing

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2016-07, Vol.143, p.252-259
• Main Authors: Chiadò, Alessandro, Palmara, Gianluca, Ricciardi, Serena, Frascella, Francesca, Castellino, Micaela, Tortello, Mauro, Ricciardi, Carlo, Rivolo, Paola
• Format: Article
• Language: English
• Subjects: AFM; Anhydrides; Biomaterials; Biosensing; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Carboxylic Acids - chemistry; Carboxylic functionalization; Crosslinking; Deposition; Devices; EDC/NHS; Glutaral - chemistry; Glutaraldehyde; Immobilization; Immunoassay; Microscopy, Atomic Force; Oriented immobilization; Photoelectron Spectroscopy; Polymerization; Polymethacrylic Acids - chemistry; Protein G; Reproducibility of Results; Signal to noise; Silanes - chemistry; Silicon - chemistry; Succinic anhydride; Succinic Anhydrides - chemistry; Surface Properties; XPS
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2016.03.048

[Display omitted] •Succinic anhydride gives a reliable surface modification for silicon-based biosensing.•High surface density of immobilized active biomolecules has been achieved.•Biomolecules functionality was investigated through an ELISA-like bioassay.•Exposed carboxylic groups were activated through an optimized EDC/NHS protocol.•Signal to noise ratio has been maximized for biosensing applications. A well-organized immobilization of bio-receptors is a crucial goal in biosensing, especially to achieve high reproducibility, sensitivity and specificity. These requirements are usually attained with a controlled chemical/biochemical functionalization that creates a stable layer on a sensor surface. In this work, a chemical modification protocol for silicon-based surfaces to be applied in biosensing devices is presented. An anhydrous silanization step through 3-aminopropylsilane (APTES), followed by a further derivatization with succinic anhydride (SA), is optimized to generate an ordered flat layer of carboxylic groups. The properties of APTES/SA modified surface were compared with a functionalization in which glutaraldehyde (GA) is used as crosslinker instead of SA, in order to have a comparison with an established and largely applied procedure. Moreover, a functionalization based on the controlled deposition of a plasma polymerized acrylic acid (PPAA) thin film was used as a reference for carboxylic reactivity. Advantages and drawbacks of the considered methods are highlighted, through physico-chemical characterizations (OCA, XPS, and AFM) and by means of a functional Protein G/Antibody immunoassay. These analyses reveal that the most homogeneous, reproducible and active surface is achieved by using the optimized APTES/SA coupling.