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

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.