Nanoparticles derived from tea leaves kill lung cancer cells

27/08/2018

Nanoparticles derived from tea leaves kill lung cancer cells

Nanoparticles derived from tea leaves could be the key to a leap forward in treating lung cancer, scientists have "accidentally" discovered.

Nanoparticles produced from tea leaves inhibit the growth of lung cancer cells, destroying up to 80% of them, new research by a joint Swansea University and Indian team has shown.

The team made this breakthrough discovery this while testing out a new method of developing a type of nanoparticle called quantum dots. These are miniscule particles which measure less than 10 nanometres. A human hair is 40,000 nanometres thick.

Although nanoparticles are already used in healthcare, quantum dots have only recently received researchers' attention. Already they are found to be versatile enough for use in a range of applications, from LCD screens and solar cells to tumour imaging and treating cancer.

Quantum dots can be created chemically, but this is complicated and expensive, and also entails toxic side effects. The Swansea-led research team was, therefore, looking into a non-toxic plant-based alternative method of developing the dots, using tea leaf extract.

Tea leaves contain a wide variety of compounds, including polyphenols, amino acids, vitamins and antioxidants. The researchers fused tea leaf extract with cadmium sulphate (CdSO4) and sodium sulphide (Na2S) and allowed the solution to incubate, a process which causes quantum dots to form. They then applied the dots to lung cancer cells.

They found:

  • Tea leaves are a simpler, cheaper and less toxic method of producing quantum dots, compared with using chemicals, confirming the results of other research in the field.
  • Quantum dots produced from tea leaves actively inhibit the growth of lung cancer cells. They penetrated into the nanopores of the cancer cells and killed up to 80% of them. This was a totally new finding, and came as a surprise to the team.

The study, titled ‘Green-Synthesis-Derived CdS Quantum Dots Using Tea Leaf Extract: Antimicrobial, BioImaging and Therapeutic Applications in Lung Cancer Cells,’ a collaborative venture between Swansea University experts and colleagues from two Indian universities, was published in the journal Applied Nano Materials.

Dr. Sudhagar Pitchaimuthu, lead researcher on the project, and a Ser Cymru-II Rising Star Fellow, explained the rationale behind the study: "The main reason we started looking at tea leaves is that chemically synthesised quantum dots cost between £250 and £500 per microgram, whereas organically-derived ones can be manufactured for £10 per microgram, and at the same time they don't poison healthy cells surrounding the cancer.

He also went on to say, "Our research confirmed previous evidence that tea leaf extract can be a non-toxic alternative to making quantum dots using chemicals.

The real surprise, however, was that the dots actively inhibited the growth of the lung cancer cells. We hadn't been expecting this.

The CdS quantum dots derived from tea leaf extract showed exceptional fluorescence emission in cancer cell bioimaging compared to conventional CdS nanoparticles.

Quantum dots are therefore a very promising avenue to explore for developing new cancer treatments.

They also have other possible applications, for example in anti-microbial paint used in operating theatres, water pollutant treatments or in sun creams.

But, realistically, harnessing the quantum dots effect into a usable treatment on humans could still be some years off.

Dr. Pitchaimuthu outlined the next steps for research:

Building on this exciting discovery, the next step is to scale up our operation, hopefully with the help of other collaborators. We want to investigate the role of tea leaf extract in cancer cell imaging, and the interface between quantum dots and the cancer cell.

We would like to set up a "quantum dot factory" which will allow us to explore more fully the ways in which they can be used.

We now need to identify an enzyme which can deliver them to cancers in living creatures, without affecting surrounding healthy tissues.

"We hope to start live laboratory trials shortly, with human clinical trials following in around two years if all goes well, so perhaps in a decade we could have a widely-available treatment.”

They could even help improve the environment, as the tea leaves used come from the third of the crop deemed unsuitable for drinking, which normally ends up in landfill.

Source: https://pubs.acs.org/doi/abs/10.1021/acsanm.8b00147