Summary

Contemporary attempts to study defects in soft matter rely mainly on optical (e.g., widefield microscopy, fluorescence microscopy, etc.) or electron and X-ray imaging techniques. These methods mainly focus on structural imaging and defect localization rather than their dynamic processes such as migration or transformation of soft matter defects.

An entirely new technique is required for studying defect dynamics, which would enable sufficiently fast detection of ultra-low electrical currents with high resolution, down to the level of single defects. The main goal of our project is the real-time investigation of nanoscale dynamic processes inside single self-assembling peptide nanofibers and their formation mechanisms using nanodiamonds with color centers.This project aims to answer fundamental questions related to nanofiber and nanogel formation. Particularly our novel experimental method will contribute to the understanding, of whether nanofiber growth occurs by extension at their ends or by incorporation of new peptide units into the existing nanofiber. Furthermore, this will allow for observation of possible movement  or migration of nanofibers and their peptide units  inside a nanogel system. The experimental  technique used in this  research is based on the quantum properties of nitrogen-vacancy centers in nanodiamonds, which are sensitive to external magnetic fields. Therefore, some building units of peptide nanofibers will be labeled with magnetic nanoparticles and some with nanodiamonds containing nitrogen-vacancy centers (Figure 1A). The relative positions between magnetic particles and nanodiamonds will be detected during the formation of nanofibers.  We expect to observe the dynamic processes of structural  changes within a single nanofiber (Figure 1B) as well as within 2D and 3D hydrogelnanofiber systems (Figure 1C). Subsequently, this novel experimental technique developed within our project can be applied to other soft materials  such as organic  semiconductors and liquid crystals to better understand them and, ultimately, improve their properties for technological applications.