Ultraviolet (UV) radiation is a part of the light spectrum with wavelengths between 10 and 400nm, which are longer than ionizing radiation and shorter than visible light. Due to their wavelengths UVR are not ionizing, meaning that they don’t change the electrical charge of atoms. However, UVR interaction with living tissue is not harmless. UVR determines local chemical reactions which influence biological behavior at cellular level, acting as a catalyst. UVR plays a role in several key metabolic processes that take place in the skin, for example Vitamin D production .
While UVR exposure is beneficial for the skin, due to their biological effect, overexposure can be harmful – causing burns and several forms of skin cancer . UVR over exposure also has an effect on the cellular matrix, especially on elastin and collagen, determining premature aging of the epidermis. The Earth’s atmosphere, especially the ozone layer has the role to filter most of the UVR from reaching the ground so only about 10% of the UV rays gets through . However, due to the ozone layer damage, in the past decades, sun exposure has become more and more dangerous, with numerous associated risks for the skin. It can be argued that the benefits of sun exposure are overweight by the risks of overdoing it. Research showed that sun cumulative exposure rather than acute episodes is responsible for associated complications, including melanoma .
The UVR spectrum is divided in UVA and UVB radiation, based on the wavelength criteria. Both UVA (wavelength 320-400nm) and UVB (wavelength 280-320nm) are recognized as carcinogenetic factors even though they act different in their interaction with living tissue. While UVB is a tumor initiator mainly through DNA mutation, UVA is a tumor promoter and accelerator by affecting the mitochondrial metabolism and increasing free radical levels. Due to its longer wavelength UVA is more aggressive because it penetrates both epidermis and dermis and in dermis it affects the three-dimensional extracellular matrix causing the loss of elasticity and thus a catalyst in skin premature aging .
UVR affects skin mainly through two destructive processes: DNA damage and Oxidative Damage. DNA damage
is mainly caused by UVB radiation which basically damages the genetic information within keratinocytes. The body is prepared to fix these damages, called photoproducts, at a normal rate, but when UVR aggression surpasses the body’s capacity to repair damaged DNA, cell mutation appears. Such a mutation can proliferate and migrate thus being a serious threat for initiation and progress of skin cancer. Oxidative damage
is mainly caused by UVA which unbalances the cellular oxidation process and increases ROS levels. High ROS levels are toxic to the cell that encloses them  .
To prevent the damage that the UVR spectrum research developed sunscreens and worked on perfecting them through the years. Sunscreens are meant to be applied on the skin before intentional sun exposure but also on the daily basis, to prevent cumulative UVR damage. Sunscreens come in various forms such as gels, lotions, spray but based on their working principle they can be divided in two categories: physical and chemical.
are based on physical UV filters – micro-particles that deflect UVR. There are two extensively used physical UV filters: titanium dioxide (TiO2) and zinc oxide (ZiO). Titanium dioxide is very efficient in UVB protection but does not offers sufficient protection in the UVA spectrum. In comparison, zinc oxide successfully and effectively covers the whole UV filter. In vivo studies showed that microfine zinc oxide has a broader attenuation spectrum comparing with TiO2, especially for long UVA wavelengths – which are the most damaging to the dermis (catalyzing premature aging).
Zinc oxide is also more cosmetically acceptable than titanium dioxide making it suitable for a variety of formulations, including moisturizing formulations for daily use and waterproof formulations . Furthermore, ZnO is neutral, safe, stable and non-irritating which makes it useful for fair, sensitive or ailing skin and for children that cannot tolerate chemical sunscreens . Studies have shown that sun protection from an early age plays a vital role in avoiding skin cancer at a latter age  thus ZnO sunscreens, which offer excellent protection against UVR is an excellent solution for children. According to the FDA, ZnO is the sunscreen ingredient with the best UVR coverage .
are based on organic components that absorb UVR, thus preventing them to reach the epidermis. There are numerous chemical components used in sunscreen formulation such as: octylcrylene, avobenzone, octinoxate, helioplex, mexoryl, uvinul and others. Chemical sunscreens have a few disadvantages: it takes time (approximately 15-20 minutes) to become active, they can induce side effects (especially in sensitive skin), and the chemical UV filters can be unstable. For example, avobenzone, one of the most frequently used organic UV filters is highly photo-unstable and needs special stabilizing compensation measures .
However, through intensive research, new and innovative chemical UV filters have been developed. BASF’s Tinosorb series with its varieties – Tinosorb M (aqueous dispersion), Tinosorb S (oil dispersible) and Tinosorb S Aqua (water soluble form of Tinosorb S) it’s a chemical UV filter produced through micro-fine particle technology. Due to its chemical and physical properties Tinosorb protects against both UVA and UVB radiation. Tinosorb acts both as an organic UV filter by absorbing the UV radiation but also – due to its micro-fine structure – as an inorganic filter, deflecting the ultraviolet radiation . Basically, Tinosorb is a hybrid UV filter, borrowing the best features from each side.
Tinosorb is a complete range of products that offers the possibility of oil in water (O/W) suspension by combining Tinosorb M/Tinosorb S with Tinosorb S aqua, thus providing the best coverage and uniform protection . Furthermore, Tinosorb is highly stable and also acts as a stabilizing agent for other, more volatile, chemical UV filters  such as avobenzone .
In a world flooded with industrially made sunscreens with dozens of unknown formulations, proportions and ingredients DIY is an excellent alternative. Producing and refining your own sunscreen is easier than one imagines and it has numerous advantages such as:
- You use known ingredients from a reliable, high quality source
- You control and refine your own recipe, based on your unique skin profile
- You can develop the perfect product for your skin, one that is not commercially available
- UV filters are easy to use and incorporate in your favorite base cream or lotion
- You can add ingredients that are good for your skin
When it comes to sunscreens the latest tendencies focus to developing organic-inorganic hybrids for UV protection in a way that will maximize the benefits and reduce the potential side effects. Studies have shown that mixing organic and inorganic UV filters has a synergic effect, with an enhance SPF and a better UVR protection coverage . This means that you can refine and produce a sunscreen that has the best features of both types.
A state of the art combination that can be easily achieved through DIY means is Tinosorb – Zinc Oxide. Both are high quality and stable active ingredients easy to incorporate in a favorite base, scientifically validated to be efficient UV filters that work both in the UVA and UVB ranges. Combining Zinc Oxide with Tinosorb M, or a mixture between Tinosorb M and Tinosorb S aqua will ensure:
- Superior UVA and UVB protection because of spectrum overlap
- A more efficient protection because of both deflecting and absorbing UVR
- A more stable sunscreen because both ZnO and Tinosorb are stable and have stabilizing effects.
- Immediate protection, starting with the moment you apply it, because ZnO protects through deflection
- A better aspect, because in a ZnO-Tinosorb formulation the white cast specific to the zinc oxide will be diminished
- Less frequent reapplication – because incrementing ZnO in a Tinosorb M – Tinosorb S aqua oil/water dispersion will ensure that the protection layer is uniform and more stable
- Less irritation – the presence of ZnO in a hybrid sunscreen will lower the possibility of rash or irritation. Zinc oxide has great skin compatibility and it is frequently used in anti-rash lotions and ointments.
- High SPF protection, ideal for the whole family
- Flexible formulation – you can add other active ingredients such as antioxidants or moisturizers to the sunscreen
Concluding, the best sunscreen is the one you know and develop yourself, using high quality, certified activity UV filters in a base cream or lotion that is ideal for your skin type. By knowing the formulation and the ingredients you can make sure that your skin is properly protected. Combining Tinosorb and ZnO will ensure that the sunscreen has great efficiency, skin compatibility and cosmetic aspect.
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