NANO VS NON-NANO PARTICLES IN SUNSCREENS
There is ongoing debate regarding the use of ingredients with nano particles versus those with non-nano particles. But what are nano and non-nano particles?
Nanoparticles are nanoscale particles, ranging between 1-100 nanometers in diameter – in other words very small particles that can be up to 80,000 times smaller than the width of a human hair.
On its arrival, nanotechnology was widely welcomed by the skin care and cosmetic industry due to the advantages they have over their large-scale counterparts including improved UV protection, stronger structure, improved electrical conductivity, improved texture, and longer shelf life.
Most of the debate has centred around the use of nano particles in sunscreens. Iron oxide and titanium dioxide have been popular in sunscreens because of their powerful UV blocking properties. However, in their conventional form they usually leave a white coating on the skin, which most people find unpleasant despite their effectiveness.
The smaller versions of these ingredients were therefore developed to make the sunscreens more transparent and therefore aesthetically pleasing to wear. From this point nanoparticles have been incorporated into other personal care products, such as: deodorants, perfumes, moisturisers, anti-ageing creams, toothpastes, soaps, lip balms, and lipsticks, shampoos, etc.
The most common types of nanomaterials used in personal care products include liposomes (for their enhanced absorption by skin); nanoemulsions (for their ability to prolong the shelf life of personal care products); nanocapsules (for their controlled release); solid lipid nanoparticles (for their enhanced UV blocking); nanocrystals (for more effective passage through skin); nanosilver and nanogold (for their enhanced antibacterial properties); dendrimers (for better delivery of active agents); cubosomes (for their low cost and potential for controlled release); hydrogels (for their prolonged effect on the place of application) and buckminster fullerene, or buckyballs (for their potential to scavenge free radicals and slow down the ageing process).
Subsequent research has however emerged showing that unlike larger non-nano particles, the miniscule size of these nano particles allows them to not only penetrate the skin but also go deeper into cells where, it is believed, they can even alter cell DNA.
However, the discussion can be taken one step further as nano particles are also divided into organic and inorganic nano particles. Zinc Oxide and Titanium Dioxide are nano inorganic UV filters whilst ingredients such as BASF’s Tinosorb® A2B and Tinosorb® M are what are known as nano organic UV filters.
The diameter of these organic UV filters, although still small, are larger than those of inorganic filters. Furthermore, according to the physico-chemical properties and test results, penetration of skin and/or cell nucleus by these particles is unlikely.
Additional benefits to using nano organic UV filters include better absorption, reflection and scattering of UV light. The use of organic nano UV filters also effectively improves the skin feeling of sunscreen formulations.
Tinosorb® A2B is an innovative organic aqueous dispersion of a micro-particulate broad-spectrum UV filter with UVB and UVAII coverage. Due to its superior UV absorption capabilities, it is one of the most innovative UV filters available on the market and provides high UV protection in the UVAII range. It is added to the water phase of cosmetic formulations contributing to the aqua light feel sunscreen consumers need.
Tinosorb® M provides the broadest-possible UV protection based on micro-fine organic particle technology. The photo-stable UV filter functions in the water phase and thus combines soluble components in the oil phase. It is highly efficient at low concentration, free of preservatives and can be processed cold.
In support of its use of nano particles in Tinosorb® A2B and Tinosorb® M, BASF points out that the safety of each nano UV filters has to be evaluated independently and that nano size alone does not define a specific toxicity. Furthermore, whilst there are limitations on the use of nano UV Filters for spray application this is solely due to a lack of in vitro testing method. Their safety has however been assessed and approved by SCCS and they appear on the approved list in the EU for other uses.