Blood Retention and Antigenicity of Polycarboxybetaine-Modified Liposomes

06 April 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Zwitterionic polycarboxybetaines (PCBs) have gained attention as alternative stealth polymers whose
liposomal formulation and protein conjugates were reported not to elicit anti-polymer antibodies. Here, we
studied the blood retention and antigenicity of liposomes modified with PCBs focusing on their chemical
structures and doses. We compared PCBs with either 1 or 3 (PCB1 or PCB3) spacer carbons between the
carboxylate and ammonium groups. PCB3-modified liposomes had a short blood retention, whereas PCB1-
modified liposomes demonstrated extended blood retention that was somewhat superior to PEGylated liposome.
This confirmed the excellent non-fouling nature of PCB1 reported previously. Interestingly, PCB1-liposome as
well as PCB3-liposome elicited specific IgMs toward each PCB. The dose-dependent production of specific
IgMs to PCB-liposomes was similar to that of PEGylated liposome, i.e., high doses of PCB-liposomes reduced
the production of specific IgMs, termed immunological tolerance. These results indicate the importance of
investigating the effect of dose to clarify the existence of antigenicity of stealth polymers


zwitterionic polymer
antibody production
accelerated blood clearance phenomenon
blood retention


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