Pakistani scientists have created fluorescent nanoparticles from spent tea leaves (STL) using an environmentally friendly process. These nanoparticles have a huge potential in sensors in different medical applications.
Aumber Abbas, who is a PhD scholar at Newcastle University, along with other researchers from Oxford University, discovered that tea waste can be converted into Graphene Quantum Dots (GQDs) and used to create a highly selective sensor for detecting iron in drinking water and in Parkinson’s patients.
The small particles are made from graphene, which is an allotrope of carbon discovered in 2004 and consists of a sheet of atoms that can be obtained from a piece of graphite using scotch tape. The discovery of this remarkable material earned the Nobel Prize. Since then, graphene has been a valuable material for research in fields such as material science, medicine, and more.
Scientists and engineers worldwide are continuing to work on refining graphene for desired results. For example, in March 2018, Pablo Jarillo-Herrero at the Massachusetts Institute of Technology (MIT) discovered that when a single-atom-thick sheet of graphene is placed on another with a slight twist, the material exhibits superconductivity. Similarly, the search for fluorescence in GQDs led the team to make additional modifications.
The team sought to make the particles glow, but graphene lacks a bandgap or energy gap. Abbas and his colleagues were able to find a solution to this problem through an alternative approach.
“One of the challenges with graphene is its zero bandgap, which restricts its optical emission and use in the field of fluorescence. To overcome this challenge, I cut the graphene sheet into small pieces, which introduced a bandgap and caused the small pieces of graphene to fluoresce,” Aumber Abbas said in a statement, adding that the team’s goal was to develop a low-cost advanced material, so they began with a waste product: “used black tea.”
The Process
Black tea waste was initially converted into black char through heat treatment at 500°C. The resulting char was further treated in a high-pressure closed vessel at 200-250°C in the presence of a chemical called Oxone. After the reaction was completed, the mixture was filtered to separate the small pieces of graphene. The filtrate liquid contained nanosized graphene sheets that began fluorescing, which demonstrates that a bandgap has been introduced in the material. This allowed the team to successfully modify the GQDs into a useful sensing material.
In the next step, the scientists used advanced instruments such as Transmission (and High Transmission) electron microscopy (TEM), Atomic force microscopy (AFM), and Fourier-transform infrared (FTIR) spectroscopy to confirm the structure, size, quality, and other characteristics of the nanodots.
According to standard tests, a single dot ranges in size from 1 to 5 nanometers and has a thickness of one nanometer. These dots are so small that one billion of them could fit end-to-end in a line one meter long drawn on a sheet, which is why they are referred to as “nano” particles (one billionth of a meter).
The GQDs are now able to detect the presence of iron or its states based on their strong blue luminescence, making them a sensor. When iron is present, it immediately switches off the fluorescence of the GQDs. The Graphene Quantum Dots were tested for 17 different metal ions dissolved in solution, and they showed the highest switching-off response in the presence of iron. This suggests that they have a promising future for detecting iron in biological or environmental systems.
Abnormal iron accumulation in the brain can lead to cognitive decline and may increase the risk of Alzheimer’s disease. Iron accumulation can also be harmful to water and environmental systems. The newly developed GQDs may be useful for detecting iron in a variety of applications.
On the other hand, the particles are made with a green, acid-free, and cost-effective approach with raw material which is abundant – the used tea.
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chep log oxford aur cambridhe students k sath zabardasti oakistani lga k drama kr rhe hn. they give an environment which does not eist here. give them credit not this pathetic pos
Dear better dig into depth before making an opposing assumption. There is a paper cited at the end from where this post is created. Check who is the first author, what is the affiliation, then check acknowledgment and funding source at the end of paper. Better you will know it’s a Pakistani’s work and that is me!
Btw, the one at Oxford is also Pakistani.