With our increased understanding of trapping in chemically fueled assembly, we tested the dynamics of assemblies by measuring the amount of peptide in the assembly as a function of time using 1 H-NMR spectroscopy (Fig. A-C). For assemblies of Fmoc-AVD fueled with 100 mM EDC at pH 6 and 6.5, we found that 66% and 60% of peptide remained in the assembly one hour after EDC addition. For assemblies of 50 mol% Fmoc-AVD and 50 mol% Fmoc-GGD at pH 6, trapped assembled peptide decreased to 30%. We used confocal microscopy to study the dynamics of assembly and disassembly further. We imaged several XYZ-stacks (z-dimension 5-10 µm) over time. After imaging the temporal z-stacks, we corrected for x/y-drift. We analyzed the change of the images as a function of time by calculating the Pearson correlation coefficient between sequential images of an area of 8.7 µm x 10.2 µm. We calculated the Pearson correlation coefficient between frames spaced apart 10 min (Fig. ). For assemblies of Fmoc-AVD at pH 6, the Pearson correlation coefficient ranges between 0.9 and 1.0 (Fig. ). A strong correlation from image to image implies a lack of assembly and disassembly. At pH 6.5, the correlation coefficient ranged from 0.75 and 1.0, which shows that the assemblies were slightly more dynamic (Fig. ). Finally, for assemblies of 50 mol% Fmoc-AVD and 50 mol% Fmoc-GGD at pH 6, the range of the correlation coefficient broadened to 0.25-1.0, indicating that these assemblies are more dynamic than pure Fmoc-AVD (Fig. ). Excitingly, we observed behavior reminiscent of the dynamic instabilities of microtubules, i.e., some fibers could switch from growing to collapsing and back to growing again. This behavior was only observed on fiber ends that were not embedded in a dense network of other fibers making it complicated to image these fibers due to the drifting of the sample. Thus, we trapped 2.5 mM of precursor solution in a 1.5% agarose gel and added a layer of 100 mM EDC on top of the gel. Doing ensured the fibers were in a pseudo-steady state (Fig. ) and tended to drift less. We imaged the samples and followed the evolution of a fiber's length as a function of time over several z-planes (5-10 µm). For Fmoc-AVD at pH 6 or pH 6.5, no noticeable growth and collapse of the dangling fibers were found (Fig. ). For the mixture of 50 mol% Fmoc-GGD and 50 mol% Fmoc-AVD assemblies, some fiber tips alternately grew and collapsed while fuel was present (Fig. ). 3D projections of the images confirmed that the fibers were not falling in and out of the focal plane but growing and shrinking (Fig.