Characterising PEGDA1000 Carbon Dots and DNA for use in plant transformation and as biostimulants

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


We require new crops with increased yields, enhanced nutritional value, and improved stress resistances in response to our presently growing human population and the changing global climate. Crop improvements have typically arisen via selective breeding and improvements to agricultural practices but are now primarily produced via faster biotechnological methods. To biotechnologically alter a plant, the process of plant transformation must occur to deliver biotechnological components inside a plant. Biostimulants, compounds applied to plants to improve their growth in a manner distinct to fertilisers, are also gaining popularity for crop improvement. Nanomaterials offer promising opportunities, as Carbon Dots (CDs), a sub-category of carbon nanomaterial, show promise as potential carriers of DNA for plant transformation, and as biostimulants.

This thesis examines the suitability of CDs functionalised with poly-ethylene glycol diamine (PEGDA1000 CDs) for both purposes. I present novel characterisation showing the first visual evidence of CDs binding to a DNA backbone and assess how various transformation buffer conditions affect CD/DNA binding. I examine the success of CD mediated transformation of wheat and find whilst the GFP screenable marker appears present via confocal imaging, it lacks molecular evidentiary support. Through further analysis I discover the fluorescent protein marker used is potentially confused with innate CD fluorescence and suggest a contraindication of fluorescent protein use alongside CDs. Additionally, I highlight a potentially wide-spread issue of CD contamination in the larger field of studying CD application to plants. Finally, I assess PEGDA1000 CDs as biostimulants, and find that the presence or absence of bound DNA as a functional group alters the effects to growth variables and photosynthesis, and posit size also affects the in planta interactions with photosynthetic machinery. I find PEGDA1000 CDs are likely inferior to PEI (polyethylenimine) CDs for plant transformation, and to glycan CDs for biostimulant purposes.
Date of Award20 Jun 2023
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorHeather M Whitney (Supervisor), M C Galan (Supervisor) & Keith Edwards (Supervisor)


  • carbon nanodots
  • Nanomaterials
  • Plant transformation
  • plant science
  • Biostimulants

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