Functionality of Immunoglobulin G and Immunoglobulin M Antibody Physisorbed on Cellulosic Films

Abstract

The functionality and aging mechanism of antibodies physisorbed onto cellulosic films was investigated. Blood grouping antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM) were adsorbed onto smooth cellulose acetate (CAF) and regenerated cellulose (RCF) films. Cellulose films and adsorbed IgG layers were characterized at the air and liquid interface by X-ray and neutron reflectivity (NR), respectively. Cellulose film 208 Å thick (in air) swell to 386 Å once equilibrated in water. IgG adsorbs from solution onto cellulose as a partial layer 62 Å thick. IgG and IgM antibodies were adsorbed onto cellulose and cellulose acetate films, air dried, and aged at room temperature for periods up to 20 days. Antibody functionality and surface hydrophobicity were measured everyday with the size of red blood cell (RBC) agglutinates (using RBC specific to IgG/IgM) and the water droplet contact angle, respectively. The functionality of the aged IgG/IgM decreases faster if physisorbed on cellulose than on cellulose acetate and correlates to surface hydrophobicity. IgG physisorbed on RCF or CAF age better and remain functional longer than physisorbed IgM. We found a correlation between antibody stability and hydrogen bond formation ability of the system, evaluated from antibody carbonyl concentration and cellulosic surface hydroxyl concentration. Antibody physisorbs on cellulose by weak dipole forces and hydrogen bonds. Strong hydrogen bonding contributes to the physisorption of antibody on cellulose into a non-functional configuration in which the molecule relaxes by rotation of hydophobic groups toward the air interface.

Effect of Bovine Serum Albumin Treatment on the Aging and Activity of Antibodies in Paper Diagnostics

“…This study suggests that hydroxyl groups are important in antibody bioactivity loss not only on cellulosic films (Huang et al, 2017b ) but also on paper and probably any substrate in diagnostics. With BSA treatment, the concentration of surface hydroxyl available is significantly reduced and paper becomes insensitive to environmental moisture.…”

“…Using model surfaces, antibody bioactivity loss was reported to involve biomolecule interaction with cellulose surface hydroxyl groups, triggering antibody irreversible adsorption and possible change of conformation (Huang et al, 2017b ). This theory has not been studied using paper, especially low-density papers such as paper towels.…”

Activity and Longevity of Antibody in Paper-Based Blood Typing Diagnostics

“…A subsequent rapid loss in activity is seen and no activity is present after 1 month of aging. This complete antibody degradation from the air-drying process may be due to a detrimental conformational change of the physisorbed antibody (Huang et al, 2017 ).…”

“…The degradation effects of high temperature, high humidity and multiple freeze-thaw cycles have been explored (Paborji et al, 1994 ; Wang et al, 2012 ). However, surprisingly little is known on the antibody-paper interaction, on the effect of the surface on the aging and adsorption morphology of antibody, or even on the degradation mechanism or shelf life of antibody solutions—and our current understanding is at best empirical (Guan et al, 2014 ; Wu et al, 2014 ; Huang et al, 2017 ). This in spite of a robust and reliable antibody practice and industry.…”

Adsorption of Soluble Immunoglobulin‐Type Adhesion Molecules to Cellulose Acetate Beads

“…Conversely, sICAM‐1 and sVCAM‐1 may have the same affinity as IgG for CA beads because these adhesion molecules structurally belong to the Ig superfamily . Additionally, the adsorption of Ig to CA has been reported as physisorption, and not as an antigen–antibody reaction . These reports suggest that sICAM‐1 and sVCAM‐1 themselves seem likely to adsorb CA beads via physisorption, and if so, it is likely that the adsorption of sICAM‐1 and sVCAM‐1 to CA beads is temperature independent (Fig.…”