Detection of Antipoly(ethylene glycol) IgM in Immune Serum by Oligo(ethylene glycol)-Conjugated Cello-oligosaccharide Assemblies

Abstract Adsorbing antibodies of interest onto solid supports displaying corresponding antigens is an efficient strategy for their subsequent purification and detection. We have previously demonstrated the potential of water-dispersible, antibiofouling, and designable cello-oligosaccharide assemblies for antibody detection via enzyme-linked immunosorbent assay (ELISA). However, whether antigen-conjugated cello-oligosaccharide assemblies can detect specific antibodies contained in immune serum remains unexplored. In this study, we demonstrate the utility of oligo(ethylene glycol) (OEG)-conjugated cello-oligosaccharide assemblies for detecting antipoly(ethylene glycol) (PEG) immunoglobulin M (IgM) in serum from immunized animals. Mouse sera containing anti-PEG IgMs, induced by immunogenic polymers, were utilized for evaluation. ELISA results revealed that anti-PEG IgMs in the serum with no heat-inactivation or depletion were successfully detected by cello-oligosaccharide assemblies displaying OEG chains with at least three repeating ethylene glycol units. ELISAs using a series of cello-oligosaccharide assemblies displaying OEG chains indicated that the conjugation rate of OEG chains influences anti-PEG IgM binding. Furthermore, increasing the serum concentration led to enhanced detection efficacy for anti-PEG IgM, likely due to the superior antibiofouling properties of the cello-oligosaccharide assemblies, which minimize nonspecific adsorption of serum proteins. The concentration of the assemblies also significantly influenced the detection efficacy. Additionally, 7 days after a single intravenous injection of OEG-conjugated cello-oligosaccharide assemblies without micrometer-scale aggregates, ELISA signals for IgMs against PEG chains, OEG chains, and cello-oligosaccharide moieties were comparable to those of saline-treated controls. These findings demonstrated that OEG-conjugated cello-oligosaccharide assemblies hold considerable potential for the detection of anti-PEG IgMs in immune serum with no heat-inactivation or depletion.