Covalent Coupling of Antibodies to Self-Assembled Monolayers of Carboxy-Functionalized Poly(ethylene glycol):  Protein Resistance and Specific Binding of Biomolecules

Abstract

We report the synthesis, film formation, protein resistance, and specific antigen binding capability of a carboxy-functionalized poly(ethylene glycol) alkanethiol [HOOC-CH2-(OCH2-CH2)n-O-(CH2)11-SH, n ) 22-45]. Despite its polymeric character, the molecule is found to form a densely packed self-assembled monolayer on polycrystalline gold, if adsorbed from dimethylformamide solution. Due to its chain length distribution, the carboxy tailgroups are expected to be partially buried within the film and, thus, do not affect the protein repulsive characteristics of the ethylene glycol moieties when exposed to fibrinogen and immunoglobulin G (IgG). However, if activated by N-hydroxysuccinimide and N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride, antibodies can be covalently coupled to the monolayer. While resistance to nonspecific fibrinogen and IgG adsorption is maintained for this biologically active layer, it exhibits high specific antigen binding capacity. The performance of this highly selective surface is compared to that of antibody films prepared by standard aminosilane chemistry.

Immunosensor interface based on physical and chemical immunoglobulin G adsorption onto mixed self-assembled monolayers

“…Surfaces with nonionic polyethylene oxide (PEO) grafts show greatly reduced protein adsorption [9], since they are able to minimize both electrostatic and hydrophobic interactions. The development of an interface of gold modified with tri(ethylene glycol)-terminated thiol has also been reported [10,11] as resistant to the nonspecific adsorption of some proteins; in this case, its laborious synthesis appears as a drawback in its use. In contrast, the addition of surfactants [12][13][14] during biocompounds immobilisation, such as sodium dodecyl sulphate (SDS) or polyethylene glycol sorbitan monolaurate (Tween 20) became common in biosensor preparation.…”

Oncologic photodynamic diagnosis and therapy: confocal Raman/fluorescence imaging of metal phthalocyanines in human breast cancer tissue in vitro

“…The efficacy of phthalocyanine derivatives as photosensitizers in recent years was signicantly enhanced by employing short-pulse irradiation with a femtosecond laser, which increases selectivity by reducing the photothermal effect on normal cells, and targeted photodynamic therapy, which increases specicity by employing photosensitizer-nanoparticle conjugates. [24][25][26][27][28][29][30] The targeted PDT is based on molecular recognition towards specic cell surface receptors, which can be achieved by conjugation with a specic antibody. Recently, targeted PDT has been employed in breast cancer cells using Her2 antibody-phthalocyanine-gold nanoparticle conjugates.…”

Interaction Analysis of the Carcinoembryonic Antigen (CEA) with Its Monoclonal Antibody Immobilized on a Gold Surface Using Fourier Transform Infrared Reflection-Absorption Spectroscopy (FT-IR RAS)

“…The obtained spectrum showed strong absorption bands at around the 1600 -1700 cm -1 region and the 1500 -1600 cm -1 region belonging to protein-specific amide bonds of amide I and amide II, respectively, and no band at 1745 cm -1 belonging to the υas(C=O) asymmetric stretch of the NHS carbonyls of the active ester. 8,13 ( Fig. 3A, a).…”

“…On the other hand, another type of non-labeling detection was recently realized by using Fourier transform infrared reflection-absorption spectroscopy (FT-IR RAS). 8 An excellent advantage of FT-IR RAS over QCM and SPR is that we can obtain structural information based on the chemical structure of target compounds. For example, we can detect the functional groups specific for biomolecules by FT-IR RAS: the amide, amino, carboxyl, etc.…”