title: Comparison of the 2D and 3D Nanostructured Lectin-Based Biosensors forIn SituDetection of Sialic Acid on Glycoproteins.
abstract: We present here comparison of a build-up of two ultrasensitive lectin biosensors based on 2D or 3D architecture. A 2D lectin biosensor was prepared by a covalent immobilisation of lectinSambucus nigraagglutinin (SNA) recognising sialic acid directly on a mixed self-assembled monolayer (SAM) on planar gold surfaces. A 3D biosensor was prepared by covalent immobilisation of SNA lectin on a mixed SAM layer formed on gold nanoparticles. Surface plasmon resonance technique allowed to follow kinetics of a mixed SAM (1:1 mixture of 11-mercaptoundecanoic acid and 6-mercaptohexanol) formation on a bare gold electrode and on an electrode modified by 5 nm and 20 nm gold nanoparticles (AuNPs). Results from the study revealed that a mixed SAM formation is slower on surfaces with increased curvature, the process of SAM formation on all surfaces is completed within 6 min, but a density of thiols on such surfaces differs significantly. Quartz crystal microbalance experiments showed that a surface density of immobilised lectin of (2.53 ± 0.01) pmol cm-2was higher on planar gold surface compared to the surface modified by 20 nm AuNPs with a surface density of (0.94 ± 0.01) pmol cm-2. Even though a larger amount of SNA lectin was immobilised on a surface of the 2D biosensor compared to the 3D biosensor, lectin molecules immobilised on AuNPs were more accessible for its analytes - glycoproteins fetuin and asialofetuin, containing different amount of sialic acid on the protein surface. Most likely a better accessibility of lectin for its analytes on a 3D surface and proper interfacial properties of a 3D surface are behind unprecedented detection limit down to aM level for the lectin biosensor based on such a nanoscale tuned interface.
authors.affiliation: Department of glycobiotechnology, Institute of chemistry, Center for glycomics, Slovak academy of sciences, Dubravska cesta 9, Bratislava 845 38, Slovak republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Bertok
authors.affiliation: Department of glycobiotechnology, Institute of chemistry, Center for glycomics, Slovak academy of sciences, Dubravska cesta 9, Bratislava 845 38, Slovak republic.
authors.forename: Alena
authors.initials: A
authors.lastname: Sediva
authors.affiliation: Department of glycobiotechnology, Institute of chemistry, Center for glycomics, Slovak academy of sciences, Dubravska cesta 9, Bratislava 845 38, Slovak republic.
authors.forename: Alica
authors.initials: A
authors.lastname: Vikartovska
authors.affiliation: Department of glycobiotechnology, Institute of chemistry, Center for glycomics, Slovak academy of sciences, Dubravska cesta 9, Bratislava 845 38, Slovak republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Tkac
keywords: Sambucus nigra lectin; biosensor; electrochemical impedance spectroscopy (EIS); glycoproteins; gold nanoparticles