Noninvasive Nanodiamond Skin Permeation Profiling Using a Phase Analysis Method: Ex Vivo Experiments.

Carbon-based nanoparticles (NPs) are widely used in nanotechnology. Among them, nanodiamonds (NDs) are suitable for biotechnology and are especially interesting for skin delivery and topical treatments. However, noninvasive detection of NDs within the different skin layers or analyzing their penetration ability is complicated due to the turbid nature of the tissue. The iterative multiplane optical properties extraction (IMOPE) technique detects differences in the optical properties of the measured item by a phase-image analysis method. The phase image is reconstructed by the multiplane Gerchberg-Saxton algorithm. This technique, traditionally, detects differences in the reduced scattering coefficients. Here, however, due to the actual size of the NDs, the IMOPE technique's detection relies on absorption analysis rather than relying on scattering events. In this paper, we use the IMOPE technique to detect the presence of the NDs within tissue-like phantoms. In addition, we perform ex vivo pigskin experiments to estimate the penetration of the NDs to the different skin layers and show that their presence reduces at deeper layers. The significance signal of the NDs within the epidermis, dermis, and fat layers gradually reduces, with t test significance values that are smaller than 10-4, 10-3, and 10-2, respectively. The IMOPE results are corroborated by TEM results and Franz-cell experiments. These results confirm that the IMOPE profiled the skin-permeation of the NDs noninvasively.

Effect of optical magnification on the detection of the reduced scattering coefficient in the blue regime: theory and experiments.

Imaging turbid media is range limited. In contrast, sensing the medium's optical properties is possible in larger depths using the iterative multi-plane optical properties extraction technique. It analyzes the reconstructed reemitted light phase image. The root mean square of the phase image yields two graphs with opposite behaviors that intersect at µ's,cp. These graphs enable the extraction of a certain range of the reduced scattering coefficient, µ's. Here, we aim to extend the range of µ's detection by optical magnification. We use a modified diffusion theory and show how µ's,cp shifts with the varying magnification. The theoretical results were tested experimentally, showing that the technique can be adapted to different ranges of µ's by changing the magnification.

Media Characterization under Scattering Conditions by Nanophotonics Iterative Multiplane Spectroscopy Measurements.

Characterizing materials is preferably done by multiple wavelengths. In opaque materials, the scattering poses a challenge due to the additional complexity to the spectroscopic measurements. We have previously demonstrated an iterative multiplane method for characterizing materials using the reflection from turbid media. Initial studies were performed in the red wavelength regime (632.8 nm) which is optimal for biomedical applications. However, in order to differentiate between materials, it is better to use multiple wavelengths, as spectroscopy may detect the material fingerprint. In this paper, our iterative multiplane optical property extraction (IMOPE) technique is presented in the blue regime (473 nm). Agar-based solid phantom measurements were conducted and compared to our theoretical model. Compatibility between experiments in the red and blue wavelengths shows the robustness of our technique.