Pitfalls in using fluorescence tagging of nanomaterials: tecto‐dendrimers in skin tissue as investigated by Cluster‐FLIM

Volz, Pierre; Schilrreff, Priscila; Brodwolf, Robert; Wolff, Christopher; Stellmacher, Johannes; Balke, Jens; Morilla, María José; Zoschke, Christian; Schäfer‐Korting, Monika; Alexiev, Ulrike

doi:10.1111/nyas.13473

Cited by 18 publications

(10 citation statements)

References 43 publications

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“…Yet, it does not discriminate between the various barriers of the skin. Combining this technique with microscopical techniques can visualize local concentrations of the dye [ 33 , 152 ] (see also Section 3.2 ).…”

Section: And How Can We Measure Them?mentioning

confidence: 99%

Skin Barriers in Dermal Drug Delivery: Which Barriers Have to Be Overcome and How Can We Measure Them?

et al. 2020

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Although, drugs are required in the various skin compartments such as viable epidermis, dermis, or hair follicles, to efficiently treat skin diseases, drug delivery into and across the skin is still challenging. An improved understanding of skin barrier physiology is mandatory to optimize drug penetration and permeation. The various barriers of the skin have to be known in detail, which means methods are needed to measure their functionality and outside-in or inside-out passage of molecules through the various barriers. In this review, we summarize our current knowledge about mechanical barriers, i.e., stratum corneum and tight junctions, in interfollicular epidermis, hair follicles and glands. Furthermore, we discuss the barrier properties of the basement membrane and dermal blood vessels. Barrier alterations found in skin of patients with atopic dermatitis are described. Finally, we critically compare the up-to-date applicability of several physical, biochemical and microscopic methods such as transepidermal water loss, impedance spectroscopy, Raman spectroscopy, immunohistochemical stainings, optical coherence microscopy and multiphoton microscopy to distinctly address the different barriers and to measure permeation through these barriers in vitro and in vivo.

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Section: And How Can We Measure Them?mentioning

confidence: 99%

Skin Barriers in Dermal Drug Delivery: Which Barriers Have to Be Overcome and How Can We Measure Them?

et al. 2020

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“…Figure 4 B–D visualizes DL skin penetration using FLIM, providing a spatially resolved image of DL distribution in the tissue (Figure 4 D). Cluster‐FLIM enhances the image contrast as well as statistical significance, [5d, 8] thereby resolving detailed skin structures (Figure 4 D). The highest DL concentration is depicted by the red fluorescence decay cluster in the false‐color coded image with the fastest fluorescence decay time, while the lowest concentration is shown in blue with the slowest fluorescence decay time (Figure 4 D, E).…”

Section: Resultsmentioning

confidence: 99%

“…where

I_{R O I}

is the fluorescence intensity in the region of interest (ROI), such as whole skin, viable epidermis or dermis,

M W

is the molecular weight, and

α

and

b

are slope and intercept of a linear fit of the concentration calibration data (Figure S18) with

b = 0

for Equation (1). The FLIM lifetime data were analyzed by a cluster algorithm, [5d, 8] which allows us to separate image pixel according to discrete lifetime clusters. We calculated the concentration from the lifetime data using Equation 2:

true c_{D L} ((), τ) = \sum_{c l u s t e r} \frac{((), \frac{τ_{c l u s t e r} - b}{α}) \times # p i x e l_{c l u s t e r}}{t o t a l # p i x e l i n R O I} \times M W \times F_{r},

…”

Section: Resultsmentioning

confidence: 99%

“…However, fluorescence lifetime imaging microscopy (FLIM) has received a lot of attention in the recent years as a sensitive tool for visualizing the spatial distribution of endogenous and exogenous fluorescent molecules at the subcellular and suborganelle level [6] . This sensitivity and signal specificity of FLIM relies on the fluorescence lifetime as an intrinsic property of a given fluorophore that is usually independent of fluorophore concentration and optical loss in the sample, [7] and inter alia provides discrimination between background fluorescence from molecules that naturally reside in tissue and the target fluorescence [5d, 8] . Moreover, fluorescence lifetime is sensitive to the environment, [6b,c, 9] as is EPR [10] .…”

Section: Introductionmentioning

confidence: 99%

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A Dual Fluorescence–Spin Label Probe for Visualization and Quantification of Target Molecules in Tissue by Multiplexed FLIM–EPR Spectroscopy

et al. 2021

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Simultaneous visualization and concentration quantification of molecules in biological tissue is an important though challenging goal. The advantages of fluorescence lifetime imaging microscopy (FLIM) for visualization, and electron paramagnetic resonance (EPR) spectroscopy for quantification are complementary. Their combination in a multiplexed approach promises a successful but ambitious strategy because of spin label‐mediated fluorescence quenching. Here, we solved this problem and present the molecular design of a dual label (DL) compound comprising a highly fluorescent dye together with an EPR spin probe, which also renders the fluorescence lifetime to be concentration sensitive. The DL can easily be coupled to the biomolecule of choice, enabling in vivo and in vitro applications. This novel approach paves the way for elegant studies ranging from fundamental biological investigations to preclinical drug research, as shown in proof‐of‐principle penetration experiments in human skin ex vivo.

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“…In addition to chemotherapy and gene delivery applications, CSTDs can also be shaped toward the applications in biological imaging. As an example, Volz et al 44 reported the use of G5/G2.5 CSTDs for fluorescence imaging of the interaction of nanocarriers with skin. First, the G5/G2.5 CSTDs were synthesized and then fluorescently labeled with a dye of fluorescein isothiocyanate (FITC).…”

Section: Biomedical Applications Of Cstdsmentioning

confidence: 99%

Synthesis and Shaping of Core–Shell Tecto Dendrimers for Biomedical Applications

et al. 2021

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In recent years, the use of poly(amidoamine) (PAMAM) dendrimers of different generations as building blocks or reactive modules to construct core–shell tecto dendrimers (CSTDs) that are superior to the performance of single-generation dendrimers has received great attention in the field of biomedical applications. The CSTDs are always based on high-generation dendrimers as the core and low-generation dendrimers as the shell; not only do they have excellent properties similar to single high-generation dendrimers, but they also have overcome some of the shortcomings (e.g., limited drug loading capacity or enhanced permeability and retention effect due to small size) of single-generation dendrimers in biomedical applications. Herein, the recent advances of CSTDs synthesized by different approaches as nanoplatforms for different biomedical applications, particularly for chemotherapy, gene delivery, and combination therapy, as well as biological imaging, are summarized. In addition, the current challenges and future perspectives of CSTDs are also discussed.

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Pitfalls in using fluorescence tagging of nanomaterials: tecto‐dendrimers in skin tissue as investigated by Cluster‐FLIM

Cited by 18 publications

References 43 publications

Skin Barriers in Dermal Drug Delivery: Which Barriers Have to Be Overcome and How Can We Measure Them?

Skin Barriers in Dermal Drug Delivery: Which Barriers Have to Be Overcome and How Can We Measure Them?

A Dual Fluorescence–Spin Label Probe for Visualization and Quantification of Target Molecules in Tissue by Multiplexed FLIM–EPR Spectroscopy

Synthesis and Shaping of Core–Shell Tecto Dendrimers for Biomedical Applications

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