Investigating reproducibility challenges in CD spectroscopy of FmocFF gels

Abstract

Fluorenylmethoxycarbonyl-diphenylalanine (FmocFF) is a widely studied low molecular weight gelator known for its ability to self-assemble into supramolecular gels with diverse applications. Despite extensive literature, the reported circular dichroism (CD) spectra of FmocFF are remarkably inconsistent, even under seemingly identical experimental conditions. In this study, we systematically investigate the factors contributing to this variability and propose a protocol for reproducible CD measurements of FmocFF in solution and gel states. We compare gelation triggers including HCl, glucono-delta-lactone (GdL), CaCl2 and dimethyl sulfoxide (DMSO)/water solvent switch, and assess the impact of sample handling, loading techniques and cuvette geometry on spectral features. Our findings demonstrate that sample homogeneity, cuvette path length and high-tension signal monitoring are critical for reliable CD analysis of short peptide-based gels. This work highlights the importance of rigorous experimental practices in interpreting the supramolecular chirality of dynamic, heterogeneous systems, such as FmocFF gels. Show more