PSI's Applied Research Activities

Jun 09, 2017

We continue our series of newsletters featuring one of PSI's widely diverse technologies, emphasizing how we focus applied research toward an important application throughout the development and demonstration process. In this issue, we highlight our studies of solar radiation on skin to help develop better sunscreens. In July's newsletter, we will highlight Rapid Emergency Evacuation Litter, a revolutionary, lightweight evacuation litter/stretcher.

PSI Studies Effects of Solar Radiation on Skin to help Develop Better Sunscreens

Under a research program from the National Institutes of Health, Physical Sciences Inc. (PSI) and the University of California, Davis (UCD) are studying the role of an excited state of oxygen produced by solar radiation as a progenitor of skin cancer. We are developing an instrument with the sensitivity required to detect the weak luminescence caused by singlet oxygen generated under typical solar illumination. In a collaborative effort, PSI has developed a prototype instrument platform and UCD is using the instrument to measure singlet oxygen production in ex vivo and in vivo studies of human skin of different types. The ex vivo studies will correlate DNA damage with both the UVA dose and the singlet oxygen production. The next phase will include extensive studies with human subjects that will better define the role of singlet oxygen in skin damage including DNA mutation. The overall goal is to work with a pharmaceutical company to help develop more effective sunscreens, especially for UVA.

Damage Pathways

The incidence of skin cancer, both melanoma and the more benign, non-melanoma forms, continues to increase in the U.S. These diseases are predominantly due to exposure to solar radiation in the ultraviolet (UV) part of the spectrum. In the U.S., there are more than 3.5 million new cases of non-melanoma skin cancer diagnosed annually. Over 76,000 new cases of melanoma are expected in 2017. Combined, these represent approximately 40% of all cancers in the U.S. The annual cost of treating skin cancers in the U.S. is estimated at $8.1 billion; about $4.8 billion for non-melanoma skin cancers and $3.3 billion for melanoma. Prevention of these diseases through development of more effective sunscreens is a major goal of this study.

Ultraviolet radiation (UV) in sunlight is a known skin carcinogen and generates reactive oxygen species in the skin. Stratospheric ozone blocks portions of the sun's spectrum. The UV spectrum that is transmitted by the ozone layer includes two subsets (UVA and UVB). The short wavelength, more energetic UVB radiation, is absorbed by the top layers of the skin and causes sunburns. The longer wavelength UVA component that includes some visible blue light penetrates much deeper into the skin. The UVA component is further subdivided into UVA2 and UVA1. The latter extends to a wavelength in the visually purple part of the spectrum and may play a major role in the formation of melanoma.

Current sunscreen product labeling guidelines require information regarding protection against both UVB and UVA. In vivo sunscreen testing against erythemogenic wavelengths (UVB and UVA2) involves evaluation of the sun protection factor (SPF). A complete assessment including UVA and UVB radiation requires a non-invasive in vivo measurement of the effects of UVA1 exposure. Previous research has shown the UVA irradiation of the skin can cause damage by breaking key bonds in the base pairs of DNA. These mutations can lead to cancer. UVA1 radiation can induce the production of multiple reactive oxygen species. Among these species, singlet oxygen can be non-invasively measured through detection of its luminescence in the near infrared part of the spectrum. Singlet oxygen is a prime candidate for causing damage to DNA.

Contract News

PSI recently received the following research contracts:

"Optical Biosensor for Real-Time Assessment of Tumor Cellularity During Core Needle Biopsy Procedures" and "Measurement of Retinal Nerves and Blood Vessels as Markers for Type I Diabetes" from the National Institutes of Health
"Conformal Coating of Fabric Process Scale-up" from the U.S. Air Force, Wright Patterson

For more PSI contract news, visit

Physical Sciences Inc. | | (978) 689-0003 |
20 New England Business Center Drive, Andover, MA 01810
© 2017 Physical Sciences Inc.
Subscribe to the PSI Newsletter