A Method for Quantification of Penetration of Nanoparticles through Skin Layers Using Near-Infrared Optical Imaging

Abstract

Our study presents a new method for tracking nanoparticle penetration through different layers of the skin using near-infrared dye-loaded nanoparticles (hydrodynamic diameter = 156 nm) and optical imaging. The dye-loaded nanoparticles were mixed in a topical skin cream, applied to human cadaver skin and incubated either for three or 24 h post-application, skin tissue was clipped between glass slides prior to imaging for signal intensity across the skin thickness using an optical imaging system. The data show that nanoparticles penetrate through all the layers of the skin but there is almost an exponential decay in the signal intensity from epidermis to dermis. Depending upon the incubation time, about 55%-59% of the total signal was seen in the epidermis and the remaining through dermis and hypodermis. The advantage of the method is that it allows quantitative analysis of the extent of penetration of nanoparticles through different layers of the skin without interference of any background signal from skin tissue, and without requiring extensive tissue processing. Our method could potentially be used to study the effect of nanoparticle properties and/or the use of different formulation additives on penetration of nanoparticles through different skin layers.

Lipid Nanoparticles for Enhancing the Physicochemical Stability and Topical Skin Delivery of Orobol

“…Notably, the deposited amount of orobol into the Strat-M membranes and human cadaver skin was higher from the NLCs formulations than that from the SLNs formulations, which might be caused by the penetration-enhancing effect of the oil added into the solid lipid of the NLCs formulations [ 16 ]. Assuming that the epidermis/dermis layer of human skin is 1–2 mm thick [ 16 , 44 ], the concentration of orobol in the target human skin layer was calculated to be 11.0–19.9 μM from F4 in Figure 6 b. Since orobol showed a potent anti-skin-aging effect via the inhibition of MMP-1 expression at a concentration range of 4–8 μM [ 15 ], it can be claimed that the prepared NLCs formulation can provide sufficient epidermal/dermal orobol concentration to exert its anti-skin-aging effect.…”

Nanomaterial Lipid-Based Carrier for Non-Invasive Capsaicin Delivery; Manufacturing Scale-Up and Human Irritation Assessment

“…Penetration images were obtained using various techniques such as optical microscopy, fluorescence microscopy, confocal laser scanning microscopy (CLSM), and Raman spectroscopy. Fluorescence microscopy is useful in cell physiology study, especially for studying skin delivery such as in permeation studies [54][55][56]. The porcine skin is a membrane barrier which can be defined by the skin layers like the human skin, enabling us to observe the fluorescent dye distribution and permeation in different layers [57].…”

Evaluating accessibility of intravenously administered nanoparticles at the lesion site in rat and pig contusion models of spinal cord injury

“…Previously, we have determined that the dye leaching from NPs is insignificant, with a cumulative release of ~1.5% in 12 hrs, 2.5% in 48 h, and 3% in 96 h, almost reaching to a plateau release phase with time when incubated in 1% bovine serum albumin (used to create sink condition) solution in PBS [17]. In our previous study, these dye loaded NPs were used to determine their biodistribution in animal models of the tumor [17], and also to study their transport across the skin layers in an ex vivo experiment [18]. The NP-specific signal in the NIR region could be quantified by appropriately setting the spectral parameters without the interference from the tissue background signal, which is insignificant in the NIR region.…”