Tiny fluorescent carbon dots could make cancer treatment safer and more effective

  • University of Sheffield researchers develop new technique to make photodynamic therapy safer, cheaper and more effective
  • New technique uses tiny carbon nanoparticles to deliver cancer drugs directly to tumours
  • Carbon nanoparticles have very little toxicity and glow making them easy to locate and monitor as they move around the body
  • Existing methods of light-based therapy use cancer drugs that are frequently toxic, leading to some patients being unable to tolerate therapy

An illustration of laser treatment of a tumour

A pioneering new technique that could make light-based cancer treatment more effective and safer for patients, while reducing its cost, has been developed by researchers from the University of Sheffield.

The study, carried out by PhD student Jose Ricardo Aguilar Cosme and overseen by an interdisciplinary team of researchers from the University’s Department of Materials Science and Engineering and Department of Oncology and Metabolism, has developed tiny carbon nanoparticles that can deliver cancer drugs to tumours.

Light-based therapy, also known as photodynamic therapy, is already a clinically-approved treatment which uses drugs that only work when exposed to light to destroy cancer cells. However, many of these drugs are frequently toxic even without light, causing many side effects in patients and leading to treatment failure.

The University of Sheffield researchers have sought to improve these drugs by using small carbon dots as a way to get the drug to the tumour. Carbon dots are fluorescent nanoparticles with very little toxicity, making them extremely useful for this application. These nanoparticles were made using common ingredients such as sucrose and citric acid, which occur naturally in various fruits.

Two different versions of the carbon dots were developed as part of the research, one with the drug bound on the surface (PpIX-CD) and one where the drug was inside the dot (PpIX@CD).

The light activated drug the University of Sheffield team used was protoporphyrin IX (PpIX).

An illustration of the carbon dots

Dr Frederik Claeyssens from the University’s Department of Materials Science and Engineering, who supervised the research, said: “When the drug was bound to the surface of a carbon dot it was four times less toxic without light while maintaining its cancer-killing effect in a lab model of melanoma skin cancer. This increases the overall effectiveness of the drug.

“An additional advantage of the carbon dots is that they glow, also known as fluorescence, which makes them very simple to locate. We observed that the particles rapidly enter tumour cells and their fluorescence makes it simple to monitor how they move round the body and how they accumulate in tumours.”

Dr Helen Bryant from the University’s Department of Oncology and Metabolism, who also supervised the research, added: “Our research has the potential to produce cheaper anticancer drugs with greater efficiency to kill tumours and less side-effects in patients. The next stage of our work is the translation of our findings to more complex models of cancer and ultimately to patients.”

Jose Ricardo Aguilar Cosme, a PhD Engineering Materials student, said: “The development of new drug delivery approaches can make drugs safer and more effective. We hope to expand our research to evaluate the efficiency of carbon dots with drugs commonly used in chemotherapy and more clinically-relevant cancer models.”

The study, Carbon dot-protoporphyrin IX conjugates for improved drug delivery and bioimaging, was funded by CONACYT and published in the journal PLOS One.

To access the full research paper, visit: https://doi.org/10.1371/journal.pone.0220210

Additional information

The University of Sheffield

With almost 29,000 of the brightest students from over 140 countries, learning alongside over 1,200 of the best academics from across the globe, the University of Sheffield is one of the world’s leading universities.

A member of the UK’s prestigious Russell Group of leading research-led institutions, Sheffield offers world-class teaching and research excellence across a wide range of disciplines.

Unified by the power of discovery and understanding, staff and students at the university are committed to finding new ways to transform the world we live in.

Sheffield is the only university to feature in The Sunday Times 100 Best Not-For-Profit Organisations to Work For 2018 and for the last eight years has been ranked in the top five UK universities for Student Satisfaction by Times Higher Education.

Sheffield has six Nobel Prize winners among former staff and students and its alumni go on to hold positions of great responsibility and influence all over the world, making significant contributions in their chosen fields.

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For further information please contact:

Sean Barton
Media Relations Officer
University of Sheffield
0114 222 9852