The Human Stratum Corneum Prevents Small Gold Nanoparticle Penetration and Their Potential Toxic Metabolic Consequences

Figure 1

En face MPT-FLIM images of treated human viable skin. Multiphoton tomography fluorescence lifetime microscopy (FLIM) images showing the layers of excised full-thickness skin (stratum corneum, granulosum, spinosum, and basale) after 24-hour treatment with gold nanoparticles. Images are pseudocoloured based on 𝛼₁% signal (skin autofluorescence 0–95% and AuNPs 95–100% signal). No AuNP signal was detected in the saline control (a)–(d); however, deposits of high signal were detected in the stratum corneum of the sodium citrate control (sodium citrate crystal aggregates).The AuNP-treated groups, 10 nm (i)–(l), 30 nm (m)–(p), and 60 nm (q)-(t), resulted in signal throughout the stratum corneum. 10 nm AuNPs were also detected in the furrows. Scale bar indicates 50 μm. Color bar, blue to red indicates 𝛼₁% 0 –100%.

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