Abstract
A reference material for virus-like particles traceable to the International System of Units (Système International d'Unités - the SI) is reported. The material addresses the need for developing reference standards to benchmark virus-like gene delivery systems and help harmonize measurement approaches for characterization and testing. The material is a major component of synthetic polypeptide virus-like particles produced by the state-of-the-art synthetic and analytical chemistry methods used to generate gene delivery systems. The purity profile of the material is evaluated to the highest metrological order demonstrating traceability to the SI. The material adds to the emerging toolkit of reference standards for quantitative biology.