Retinoic Acid (IMAGE)
Caption
Label-free chemical imaging of drug delivery with SRS microscopy. The top layer of the skin, stratum corneum, is the main barrier against topically applied drugs. The understanding of the diffusion process is critical for drug delivery. However, conventional Raman microscopy requires a long averaging time and high laser powers, where fluorescence microscopy often requires dye labels that are bigger than drug molecules and alter a drug's efficacy and diffusion characteristics. This figure shows SRS images of the penetration pathways for the common drug against acne, retinoic acid. Retinoic acid diffuses through the lipid phase of the stratum corneum (polygonal shape), and is visualized by tuning the Raman shift into the characteristic band at 1570cm-1 (blue). Three-dimensional sectioning capabilities, subcellular resolution and the high sensitivity of SRS are critical for this study.
Credit
Chris Freudiger, Wei Min, and Brian Saar, Harvard University
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