A molecule that protects plants from overexposure to harmful sunlight thanks to its flamenco-style twist could form the basis for a new longer-lasting sunscreen, according to chemists from the University of Warwick.

Research on the green molecule by the scientists has revealed that it absorbs ultraviolet light and then disperses it in a ‘flamenco-style’ dance, making it ideal for use as a UV filter in sunscreens.

As well as being plant-inspired, this molecule is also among a small number of suitable substances that are effective in absorbing light in the Ultraviolet A (UVA) region of wavelengths. 

It opens up the possibility of developing a naturally-derived and eco-friendly sunscreen that protects against the full range of harmful wavelengths of light from the sun.

The UV filters in a sunscreen are the ingredients that predominantly provide the protection from the sun’s rays. In addition to UV filters, sunscreens will typically also include:

• Emollients, used for moisturising and lubricating the skin
• Thickening agents
• Emulsifiers to bind all the ingredients
• Water
• Other components that improve aesthetics, water resistance, etc.

The researchers tested a molecule called diethyl sinapate, a close mimic to a molecule that is commonly found in the leaves of plants, which is responsible for protecting them from overexposure to UV light while they absorb visible light for photosynthesis.

They first exposed the molecule to a number of different solvents to determine whether that had any impact on its (principally) light absorbing behaviour.

They then deposited a sample of the molecule on an industry standard human skin mimic where it was irradiated with different wavelengths of UV light.

When irradiated the molecule absorbs light and goes into an excited state but that energy then has to be disposed of somehow. The team of researchers observed that it does a kind of molecular ‘dance’ a mere 10 picoseconds (ten millionths of a millionth of a second) long: a twist in a similar fashion to the filigranas and floreos hand movements of flamenco dancers. That causes it to come back to its original ground state and convert that energy into vibrational energy, or heat.

It is this ‘flamenco dance’ that gives the molecule its long-lasting qualities. When the scientists bombarded the molecule with UVA light they found that it degraded only three per cent over two hours, compared to the industry requirement of 30 per cent.

Would you welcome a sunscreen that could last 10 times longer than regular sunscreen?