Advantages/disadvantages of organics

Organic components used in sunscreen formulations are fairly abundant and diverse in comparison to inorganic. This gives manufactures flexibility with characteristics of the formulation such as the sun protection factor (SPF), water resistance, and product feel. Organic components could be considered less effective because they absorb UV radiation rather than reflecting or causing it to scatter. This makes them vulnerable to photodegradation and prone to generating ROS. However, the main concern and greatest risk with using organics is the threat of carcinogens or generating carcinogens in the presence of UV light.

Future directions in uv protection

Advancing the field of UV protection is achieved by optimizing the photostability of the sunscreen while protecting against the broadest possible spectrum of UV light. This section summarizes a few of the recent studies which present novel ideas in UV protection and areas for future study.

Technology

Solvothermal synthesis is a method of producing chemical compounds. It is very similar to the hydrothermal route (where the synthesis is conducted in a stainless steel autoclave), the only difference being that the precursor solution is usually not aqueous (however, this is not always the case in all literature uses of the expression). Using the solvothermal route gains one the benefits of both the sol-gel^[1] and hydrothermal routes.^[2] Thus solvothermal synthesis allows for the precise control over the size, shape distribution, and crystallinity of metaloxide nanoparticles or nanostructures. These characteristics can be altered by changing certain experimental parameters, including reaction temperature, reaction time, solvent type, surfactant type, and precursor type.

Solvothermal synthesis has been used in laboratory to make nanostructured titanium dioxide, graphene, carbon and other materials.

The high photocatalytic capacity of TiO₂ leads to the degradation of organic  and biological molecules  into smaller and less harmful compounds. Because of their small size, TiO₂ nanostructures also provide increased surface area at which photocatalytic reactions may occur, increasing their activity. This photocatalytic activity may be applied to air purification,^] self-sterilization, water purification and molecular hydrogen production. Thus the ability of solvothermal synthesis to precisely tailor TiO₂ nanostructures has the potential to maximize the efficiency of those nanostructures in applications.

Conclusion

Sunscreen formulations have adapted and improved to become protective over a broader spectrum of light and maintain greater photostability. Sunscreens are comprised of organic and inorganic nanoparticles which act as chemical and physical UV protectors, respectively. Sunscreen components are limited by their spectrum of protection, photostability or often a combination of both. Recent studies using solid lipid nanoparticles (SLN), new organic molecules, inorganics and antioxidants attempt to optimize UV protection. In this review, we examine traditional and emerging sunscreen components and highlight novel ideas in UV protection which may provide pathways for future studies.