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Formation and Characterization of Self-Assembled Phenylboronic Acid Derivative Monolayers toward Developing Monosaccharide Sensing-Interface

View Article: PubMed Central

ABSTRACT

We designed and synthesized phenylboronic acid as a molecular recognition model system for saccharide detection. The phenylboronic acid derivatives that have boronic acid moiety are well known to interact with saccharides in aqueous solution; thus, they can be applied to a functional interface of saccharide sensing through the formation of self-assembled monolayer (SAM). In this study, self-assembled phenylboronic acid derivative monolayers were formed on Au surface and carefully characterized by atomic force microscopy (AFM), Fourier transform infrared reflection absorption spectroscopy (FTIR-RAS), surface enhanced Raman spectroscopy (SERS), and surface electrochemical measurements. The saccharide sensing application was investigated using surface plasmon resonance (SPR) spectroscopy. The phenylboronic acid monolayers showed good sensitivity of monosaccharide sensing even at the low concentration range (1.0 × 10−12 M). The SPR angle shift derived from interaction between phenylboronic acid and monosaccharide was increased with increasing the alkyl spacer length of synthesized phenylboronic acid derivatives.

No MeSH data available.


(a) Relative SPR angle shifts according to the immobilization of phenylboronic acids. (b) FTIR-RAS spectra of phenylboronic acid monolayers on Au.
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f2-sensors-07-01480: (a) Relative SPR angle shifts according to the immobilization of phenylboronic acids. (b) FTIR-RAS spectra of phenylboronic acid monolayers on Au.

Mentions: The immobilization process of synthesized phenylboronic acids was investigated by SPR. In the immobilization process of phenylboronic acids, SPR angle shifts reflect the change of dielectric constant induced by formation of an organic monolayer on the metal surface. As the number of immobilized molecules increased, SPR angle shifts gradually increased and became saturated at inner 10 h in all case (Fig. 2 (a)). SPR angle shifts (Δθ) caused by the immobilization of phenylboronic acids were 0.32° (1, 2) and 0.18° (3), respectively. Based on the result of surface electrochemical measurements that will be discussed later, 3 SAM showed the highest surface coverage. This means that 3 SAM has a larger amount of immobilized molecules than other phenylboronic acid SAM on the Au surface; at the same time it has the structure most perpendicular to the Au surface among the three phenylboronic acid SAM. In case of 3 SAM, although the number of immobilized molecules is the largest, the SPR angle shift due to the immobilization of 3 is smaller than that of other phenylboronic acid SAM. This may be caused by 3 SAM which has a well-standing structure and its benzene ring is far away from the Au surface. On the other hand, 1 and 2 SAM have a more declined structure on the Au surface. Accordingly, their benzene ring moiety is localized closer to the Au surface than that of 3 SAM. Thus, in case of 1 and 2, it was suspected that the SPR angle shift was amplified due to the proximity of the benzene ring to the Au surface.


Formation and Characterization of Self-Assembled Phenylboronic Acid Derivative Monolayers toward Developing Monosaccharide Sensing-Interface
(a) Relative SPR angle shifts according to the immobilization of phenylboronic acids. (b) FTIR-RAS spectra of phenylboronic acid monolayers on Au.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814864&req=5

f2-sensors-07-01480: (a) Relative SPR angle shifts according to the immobilization of phenylboronic acids. (b) FTIR-RAS spectra of phenylboronic acid monolayers on Au.
Mentions: The immobilization process of synthesized phenylboronic acids was investigated by SPR. In the immobilization process of phenylboronic acids, SPR angle shifts reflect the change of dielectric constant induced by formation of an organic monolayer on the metal surface. As the number of immobilized molecules increased, SPR angle shifts gradually increased and became saturated at inner 10 h in all case (Fig. 2 (a)). SPR angle shifts (Δθ) caused by the immobilization of phenylboronic acids were 0.32° (1, 2) and 0.18° (3), respectively. Based on the result of surface electrochemical measurements that will be discussed later, 3 SAM showed the highest surface coverage. This means that 3 SAM has a larger amount of immobilized molecules than other phenylboronic acid SAM on the Au surface; at the same time it has the structure most perpendicular to the Au surface among the three phenylboronic acid SAM. In case of 3 SAM, although the number of immobilized molecules is the largest, the SPR angle shift due to the immobilization of 3 is smaller than that of other phenylboronic acid SAM. This may be caused by 3 SAM which has a well-standing structure and its benzene ring is far away from the Au surface. On the other hand, 1 and 2 SAM have a more declined structure on the Au surface. Accordingly, their benzene ring moiety is localized closer to the Au surface than that of 3 SAM. Thus, in case of 1 and 2, it was suspected that the SPR angle shift was amplified due to the proximity of the benzene ring to the Au surface.

View Article: PubMed Central

ABSTRACT

We designed and synthesized phenylboronic acid as a molecular recognition model system for saccharide detection. The phenylboronic acid derivatives that have boronic acid moiety are well known to interact with saccharides in aqueous solution; thus, they can be applied to a functional interface of saccharide sensing through the formation of self-assembled monolayer (SAM). In this study, self-assembled phenylboronic acid derivative monolayers were formed on Au surface and carefully characterized by atomic force microscopy (AFM), Fourier transform infrared reflection absorption spectroscopy (FTIR-RAS), surface enhanced Raman spectroscopy (SERS), and surface electrochemical measurements. The saccharide sensing application was investigated using surface plasmon resonance (SPR) spectroscopy. The phenylboronic acid monolayers showed good sensitivity of monosaccharide sensing even at the low concentration range (1.0 × 10−12 M). The SPR angle shift derived from interaction between phenylboronic acid and monosaccharide was increased with increasing the alkyl spacer length of synthesized phenylboronic acid derivatives.

No MeSH data available.