Active Deposition and Penetration
FTIR and Raman Microspectroscopy
Obtaining a clear picture of how dermatological actives penetrate the skin is vital for optimizing topical formulations and supporting claims. Imaging surface deposition and retention is also important for many applications, particularly sunscreen and rinse-off systems. Fourier-transform Infra-Red (FTIR) microspectroscopy and Raman microspectroscopy are powerful tools for imaging active diffusion and deposition inside human ex-vivo skin samples.
A large range of vibrational spectroscopy instruments is available to TRI for imaging active delivery. The Spotlight 400 system from Perkin Elmer, and the Lumos II FTIR imaging system from Bruker for the FTIR microspectroscopy, and the Alpha-300R Confocal Raman Microscope from WITec for the Raman microspectroscopy. These imaging methods have several advantages over traditional optical microscopy techniques, including no need for stains or specific labeling to visualize actives, semi-quantitative measurements, and, in most cases, non-invasive testing protocols (i.e., no need for biopsies and sectioning). TRI has many years of experience in using these methods for a wide range of projects, mainly to visualize active inside biological tissues like skin, hair and nail which are relevant for cosmetic purpose but also inside several other substrates like fabric, patches, teeth or bone. Please contact us to design a protocol that best fits your needs.
ATR-FTIR images showing the caffeine distribution inside human stratum corneum. Tape-stripping was used to assess the depth of active delivery into the skin. Caffeine (red and yellow) can be observed to penetrate deeper from formulations containing dimethyl isosorbide (DMI) a skin penetration enhancer.
Confocal Raman images showing the caffeine penetration into human skin samples. Images show confocal cross-sections of the skin taken without the need for actual tissue sectioning. Caffeine (red and yellow) can be observed to penetrate deeper from formulations containing dimethyl isosorbide (DMI).