TY - THES A1 - Ruiz, Yudit T1 - Investigation of Self-Healing in Fruit Epidermis with Atomic Force Microscopy N2 - Different advanced microscopy techniques, mainly atomic force microscopy and scanning electron microscopy are used to inspect damage healing on fruit epidermis using squash – Cucurbita pepo L. – as prime specimen. The approach and methods used followed instructions reported by comparable projects studying epicuticular wax regeneration with SEM and AFM. However, novel detailed and instructive information was collected and reported on how to perform tasks involving certain degrees of technical difficulty, such as using AFM to find a particular location on a sample that is, by definition, thousands of times larger than the target focal zone. A non-reported system was used to trace and cut out the damages on the fruit surface. The manipulation and lithography mode of the AFM JPK software is known to work to trace micro-scale designs on hard surfaces such as CDs but we prove it can also be used on soft and very irregular surfaces such as that of C. pepo – to a certain extent. A total of 19 scratches and one round-shaped damage were cut and optical information was collected through time with AFM. All relevant parameters were measured with the JPKs built-in measuring tool and information was collected and later plotted on excel spreadsheets. Damage sealing was found to happen for all cases and for almost all different parameters -length, depth, width. The characteristics of all cases reported are unique – follow up times vary from minutes to hours and other features such as initial damage size and the force applied for its creation are different. However, damage sealing did not seem to correlate with any of these. Samples cut from specimens several days after purchase or simply from specimens with a rough, dry surface seemed to progress much more slowly than those coming from fresh-looking samples. The focus of the study was the fruit cuticle (stiff polymeric film covering the outer surface of all higher plants). To make sure that the processes of healing observed actually correspond to this part a) wax was removed in all of the samples and b) the cuticle of our model fruit was measured with light microscopy, showing that its thickness is much higher than the deepest of our AFM scratches. This way we aimed to prove that the regeneration observed represents actual cellulose regrowth and cellular activity healing the cutin layer. Progress is observed in all cases, which is a good sign. However, wax is known to regenerate immediately after removal in experiments with leaves. The fact that some of our damages seal within the first 10 minutes of observation may be an indication that wax is filling the scratch instead of other biological activity. Further research is needed to clarify the nature of this process. Y1 - 2022 ER -