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Can you imagine a computer or handheld device backlight or display of the future being lit up by a turmeric or pomegranate mixture? Imagine if an entirely edible source of white light could be generated with minimal environmental and human health impacts? The good news is that we no longer have to rely on our imagination. We now have the science to show it is indeed possible!
What could be more unnatural and yet indispensable in the modern world than a light bulb? Made from metal, glass, and a variety of petrochemicals, who would even consider looking for a "green" alternative? And if so, what would that be?
Now, a groundbreaking new study published in Scientific Reports seems to have found exactly such a green solution. Amazingly, Indian researchers discovered that a mixture of two commonly consumed edible plants, red pomegranate and turmeric, when exposed to light wavelengths just below the visible threshold (380 nm), produced almost pure white light emission (WLE).
This finding represents a simple, cheap and environmentally safe alternative to current LED technology, which presently rely on toxic materials, including heavy metals such as arsenic, copper, nickel, and lead, in their production.
In the new study titled "White Light Emission from Vegetable Extracts," Indian researchers described how they were able to conveniently tune the color temperature of the WLE by adjusting the concentrations of the "the primary emitting pigments," namely, anthocyanins from red pomegranate seed juice and curcumin extract from turmeric.
One of the crucial mechanisms behind their ability to produce an almost pure white light emission was identified as "Foster resonance energy transfer" (FREF). FREF is a mechanism that describes energy transfer between two light-sensitive molecules (known as chromophores). The researchers identified A FRET-like, light-induced energy transfer cascade: polyphenolics > curcumin > anthocyanins, resulting in WLE.
The researchers were also able to create an entirely edible gelatin-based mixture of the plant extracts that was capable of emitting almost pure white light when exposed to UV light, depicted below.
The researchers summarized their findings:
In summary, we have generated white light emission from natural dyes extracted in our laboratory using a green and simple procedure. The optimized mixture of two suitably chosen plant extracts using acidic ethanol, aided by a FRET cascade from polyphenolics to curcumin to anthocyanins, generates almost pure white light, with CIE values of (0.35, 0.33) in solution, (0.26, 0.33) in gelatin gel and (0.33, 0.25) in PVA film. White light emission from such cheap and nature friendly resources could be important in the context of lighting and sensing application. It would be interesting to see if such system can be used as dyes for tunable dye laser applications. To the best of our knowledge this is the first time low cost, biocompatible (edible) natural dyes have been a part of white light emitting system. Given the vast number of excellent natural fluorescent dyes obtainable from renewable biosources, approaches similar to the present could lead to a more extensive range of low-cost and efficient WLE biomaterials with ease of adjusting colour temperature, which will obviate more expensive alternatives currently being pursued." [emphasis added]
The researchers also described the context within which their finding may have revolutionary implications for future technology:
"White light emitting materials have attracted significant attention in recent years as key components in display and lighting devices based on LEDs. LEDs accounts for almost 20% of the total worldwide energy consumption and have wide applications in backlights, displays, lasers and indicators. White light emission has also been used for sensing. There has been a high level of interest in recent years in looking for white light emitting organic and inorganic molecules and materials, when photoexcited at near UV wavelengths."
Clearly this study holds great promise for a sustainable future. We've already identified numerous properties within plants like turmeric and pomegranate which indicate they are far superior to conventional drug-based interventions for disease prevention and treatment. We are only now learning about the technological applications of these remarkable substances and it is likely we are still only scratching the surface.