Enhancing the Sensitivity of Biotinylated Surfaces by Tailoring the Design of the Mixed Self-Assembled Monolayer Synthesis

Publication year: 2020
Authors: Blasi D. ‡†, Sarcina L. ‡§, Tricase A. ‡§, Stefanachi A. ‖, Leonetti F.*‖, Alberga D. $, Mangiatordi* Ͱ, Manoli K. †§, Scamarcio G. ◊∫, Picca R.A. *†§, Torsi L. †§#

† - CSGI, Unità di Bari,Via Orabona 4, 70125 Bari, Italy

§ - Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro,Via Orabona 4, 70125 Bari, Italy

‖ - Dipartimento di Farmacia– Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy

$ - CINECA, Via Magnanelli 6/3, 40033 Casalecchio di Reno, Italy
Ͱ - CNR – Institute of Crystallography, Via Amendola 122/o,70126 Bari, Italy
◊ - Dipartimento di Fisica ‘‘M. Merlin’’, Università degli Studi di Bari Aldo Moro, Via Amendola 173, 70126 Bari,Italy
∫ - IFN CNR, Sede secondaria di Bari, Via Amendola 173, 70126 Bari, Italy
# - Physics and Center for Functional Materials, Faculty of Science and Engineering, Åbo Akademi University, Porthansgatan 3, 20500 Åbo , Finland
‡ - Authors contributed equally to the wor
Published in: ACS Omega 2020, Vol. 5, 27, p. 16762–16771
doi: 10.1021/acsomega.0c01717

Thiolated self-assembled monolayers (SAMs) are typically used to anchor on a gold surface biomolecules serving as recognition elements for biosensor applications. Here, the design and synthesis of N-(2-hydroxyethyl)-3-mercaptopropanamide (NMPA) in biotinylated mixed SAMs is proposed as an alternative strategy with respect to on-site multistep functionalization of SAMs prepared from solutions of commercially available thiols. In this study, the mixed SAM deposited from a 10:1 solution of 3-mercaptopropionic acid (3MPA) and 11-mercaptoundecanoic acid (11MUA) is compared to that resulting from a 10:1 solution of NMPA:11MUA. To this end, surface plasmon resonance (SPR) and attenuated total reflectance infrared (ATR-IR) experiments have been carried out on both mixed SAMs after biotinylation. The study demonstrated how the fine tuning of the SAM features impacts directly on both the biofunctionalization steps, i.e., the biotin anchoring, and the biorecognition properties evaluated upon exposure to streptavidin analyte. Higher affinity for the target analyte with reduced nonspecific binding and lower detection limit has been demonstrated when NMPA is chosen as the more abundant starting thiol. Molecular dynamics simulations complemented the experimental findings providing a molecular rationale behind the performance of the biotinylated mixed SAMs. The present study confirms the importance of the functionalization design for the development of a highly performing biosensor.


MP-SPR keywords: binding, biomolecule, bound mass, interaction, protein, self-assembled monolayer (SAM)