title: Optimization and characterization of a homogeneous carboxylic surface functionalization for silicon-based biosensing.
abstract: 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.
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy. Electronic address: alessandro.chiado@polito.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Chiadò
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Palmara
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Ricciardi
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Frascella
authors.affiliation: Istituto Italiano di Tecnologia, Center for Space Human Robotics, C.so Trento 21, 10129 Torino, Italy.
authors.forename: Micaela
authors.initials: M
authors.lastname: Castellino
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Tortello
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Ricciardi
authors.affiliation: Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy. Electronic address: paola.rivolo@polito.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Rivolo
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D002264:Carboxylic Acids / Q000737:chemistry*; D005976:Glutaral / Q000737:chemistry; D018625:Microscopy, Atomic Force; D056951:Photoelectron Spectroscopy; D011109:Polymethacrylic Acids / Q000737:chemistry; D015203:Reproducibility of Results; D012821:Silanes / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*; D013387:Succinic Anhydrides / Q000737:chemistry; D013499:Surface Properties
chemical_list: D002264:Carboxylic Acids; D011109:Polymethacrylic Acids; D012821:Silanes; D013387:Succinic Anhydrides; C024702:aminopropylsilane; C031801:succinic anhydride; D005976:Glutaral; D012825:Silicon
keywords: AFM; Biosensing; Carboxylic functionalization; EDC/NHS; Immunoassay; Oriented immobilization; Protein G; Signal to noise; Succinic anhydride; XPS