Confocal laser scanning microscopy to estimate nanoparticles’ human skin penetration in vitro

Abstract

Objective With rapid development of nanotechnology, there is increasing interest in nanoparticle (NP) application and its safety and efficacy on human skin. In this study, we utilized confocal laser scanning microscopy to estimate NP skin penetration. Methods Three different-sized polystyrene NPs marked with red fluorescence were applied to human skin, and Calcium Green 5N was used as a counterstain. Dimethyl sulfoxide (DMSO) and ethanol were used as alternative vehicles for NPs. Tape stripping was utilized as a barrier-damaged skin model. Skin biopsies dosed with NPs were incubated at 4°C or 37°C for 24 hours and imaged using confocal laser scanning microscopy. Results NPs were localized in the stratum corneum (SC) and hair follicles without penetrating the epidermis/dermis. Barrier alteration with tape stripping and change in incubation temperature did not induce deeper penetration. DMSO enhanced NP SC penetration but ethanol did not. Conclusion Except with DMSO vehicle, these hydrolyzed polystyrene NPs did not penetrate intact or barrier-damaged human “viable” epidermis. For further clinical relevance, in vivo human skin studies and more sensitive analytic chemical methodology are suggested.

NIR‐Emitting Gold Nanoclusters–Modified Gelatin Nanoparticles as a Bioimaging Agent in Tissue

“…However, the ability to image NPs together with skin structure will give visual evidence about the NP penetration within the tissue. In this regard, others resort to either dual‐channel imaging followed by subsequent images overlapping, or staining of skin prior to NP examination . AuAgS–GNPs showed well‐detected fluorescence in the red region of the spectrum ( Figure a).…”

Gel-Based Nanocarrier for Intravesical Chemotherapy Delivery: In Vitro and In Vivo Study

“…The CLSM technique is a useful imaging tool for a better understanding of the nanocarriers in delivering therapeutic compounds into tissue layers [23,24]. To evaluate the efficacy of experimental nanocarrier, the CLSM was used to analyze the rhodamine B distribution in the bladder (including depth and intensity) after 1 h application in both nanocarrier and control groups.…”

“…nanocarrier formulation was significantly increased (p < 0.05), indicating that the nanocarrier exhibited potential penetration capacity. The results may be attributed to (1) the nanocarrier having increased thermodynamic activity of the therapeutic compounds thereby enhancing its partitioning into the biological membrane; and (2) the components of the formulation, particularly surfactant and cosurfactant acting as penetration enhancers to reduce the diffusional barrier of the membranous epithelium and enhance the drug permeability through epithelium membranous [23][24][25].…”

“…Computerized Zeiss Confocal laser scanning microscopy (CLSM) apparatus (FV 500, Olympus, Tokyo, Japan) was used to acquire the fluorescent images [23,24]. The bladder tissue was collected following in vivo intravesical experiments.…”

Detection of Intracellular Gold Nanoparticles: An Overview

“…One of the most widely employed method of detecting AuNPs is through fluorescence with the use of fluorescent molecules attached to the gold surface or by fluorescent gold core [ 21 , 22 , 23 ]. The fluorescence can be estimated by wild field microscopy [ 24 ], or, for enhanced resolution, by confocal laser scanning microscopy [ 25 ]. Transmission electron microscopy (TEM) is a widely used microscopy technique for the intracellular detection of metal NPs bigger than 5 nm [ 26 , 27 ].…”