Immunoactivity of self-assembled antibodies investigated by atomic force microscopy

Abstract

Immunoglobulin G (IgG), an antibody, plays a significant role in the immune system, and the functions of IgG molecules have been studied in many research fields such as medicine and engineering. Recently, we found the self-assembly of monoclonal mouse IgG molecules on a mica substrate using atomic force microscopy (AFM); the IgG molecules self-assemble into hexamers and the hexamers form a two-dimensional (2D) crystal. The self-assembly of the IgG molecules is of great interest in terms of the enhancement of the immunoactivity of the antibodies. In this study, we investigated the self-assembly of various IgG molecules on a mica substrate to discuss if the hexamerization of the IgG molecules is a general phenomenon. We also investigated the antigen binding site in the IgG antibody hexamers, and estimated the association rate constant of the self-assembled IgG molecules based on the AFM measurements.The estimated value was lower than that reported in a previous study probably because of the limited mobility of the antigen-binding fragments on the substrate.

On-Membrane Dynamic Interplay between Anti-GM1 IgG Antibodies and Complement Component C1q

“…In recent studies, the binding of C1q with IgG oligomers was studied, most notably by employing artificially hexamerized IgG antibodies [11][12][13][14]. It has been reported that IgG molecules have the potential ability to form hexamers in crystal or on mica surface under certain conditions [14,24]. In human IgG, the hexamer formation could be enhanced by triple mutation at the C H 3 domain (i.e., E345R, E430G, and S440Y), which improves the complement activating activity [14].…”

Strongyloidiasis Serological Analysis with Three Different Biological Probes and Their Electrochemical Responses in a Screen-Printed Gold Electrode

“…Atomic force microscopy (AFM) was performed to evaluate the morphological changes on the surface of the electrode after the interaction of the peptide with the serum from Groups 1, 2 and 3. This technique is used to visualize images of surfaces with antigens (Ag) or antibodies (Ab) adsorbed or combined due to Ag-Ab recognition [ 15 , 16 , 17 ].…”

“…Firstly, we must consider that the detergent phase (DP) extracted from S. venezuelensis is formed by a pool of hydrophobic proteins of the parasite [ 4 ], and its interaction with the gold electrode may occur through hydrophobic, ionic interactions or chemical bonds by thiol groups, depending on the type and amino acid sequences that form these proteins. Due to the protein diversity and probably due to the predominance of weak physical interactions between gold and these amino acids, the surface functionalization will occur in a more disordered way and we will not always have the free epitopes for regions of free contact with the immunoglobulins [ 4 , 5 , 17 , 18 ]. In these cases, some of the probes could not recognize their target, which could interfere with the values of the oxidation current measured, explaining the smaller differentiation between the groups in the DP fraction.…”

Controlling the Self-Assembly of Biomolecules into Functional Nanomaterials through Internal Interactions and External Stimulations: A Review

“…It is possible to utilize specific molecule–molecule recognitions, such as the ligand–receptor [ 95 , 96 , 97 ] and antigen–antibody [ 98 , 99 ] bindings, to guide the self-assembly of biomolecules to form ordered nanostructures and nanomaterials.…”

“…The formation of antigen–antibody immunocomplexes is helpful for the molecular self-assembly and the formation of functional bionanomaterials. For instance, Kominami and co-workers investigated the self-assembly of immunoglobulin G (IgG) on a mica surface, and found the formation of 2D hexameric IgG crystal [ 99 ]. Therefore, the antigen (anti-human serum albumin) could be bound onto the IgG hexamer via the antigen–antibody binding.…”