ArticleScientific reports2021
Non-invasive skin sampling of tryptophan/kynurenine ratio in vitro towards a skin cancer biomarker.
Article in Scientific reports, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 16 papers.
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Who cites it
16 citing papers in PubMed.
- Optimization of a 3D Skin Equivalent Incorporating Melanocytes or Melanoma Cells for In Vitro Melanoma Research.Bioengineering (Basel, Switzerland) · 2026Article
- Deciphering the role of histidine in cancer.Nature medicine · 2026Article
- Epidermal Patch Technologies for Integrated Healthcare and Infection Management.Advanced healthcare materials · 2026Review
- Effect of pH on niacinamide skin permeation.Scientific reports · 2026Article
- Article
- From Microbial Switches to Metabolic Sensors: Rewiring the Gut-Brain Kynurenine Circuit.Biomedicines · 2025Review
- Article
- Unveiling the skin microbial guardians and assailants in psoriasis subtypes: a Mendelian randomization study.Archives of dermatological research · 2024Article
- Molecular mechanisms and therapeutic significance of Tryptophan Metabolism and signaling in cancer.Molecular cancer · 2024Review
- Exploring the Surface: Sampling of Potential Skin Cancer Biomarkers Kynurenine and Tryptophan, Studied on 3D Melanocyte and Melanoma Models.Biomolecules · 2024Article
- Investigating the Free Volumes as Nanospaces in Human Stratum Corneum Lipid Bilayers Using Positron Annihilation Lifetime Spectroscopy (PALS).International journal of molecular sciences · 2024Article
- Bicontinuous Cubic Liquid Crystals as Potential Matrices for Non-Invasive Topical Sampling of Low-Molecular-Weight Biomarkers.Pharmaceutics · 2023Article
- Non-Invasive, Topical Sampling of Potential, Low-Molecular Weight, Skin Cancer Biomarkers: A Study on Healthy Volunteers.Analytical chemistry · 2022Article
- Hydrogels and Cubic Liquid Crystals for Non-Invasive Sampling of Low-Molecular-Weight Biomarkers-An Explorative In Vivo Study.Pharmaceutics · 2022Article
- Reverse Iontophoretic Extraction of Skin Cancer-Related Biomarkers.Pharmaceutics · 2021Article
- Catalase Activity in Keratinocytes, Stratum Corneum, and Defatted Algae Biomass as a Potential Skin Care Ingredient.Biomedicines · 2021Article
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Authors and funding
6 authors.
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No grant is acknowledged in the PubMed record.
Abstract
The tryptophan to kynurenine ratio (Trp/Kyn) has been proposed as a cancer biomarker. Non-invasive topical sampling of Trp/Kyn can therefore serve as a promising concept for skin cancer diagnostics. By performing in vitro pig skin permeability studies, we conclude that non-invasive topical sampling of Trp and Kyn is feasible. We explore the influence of different experimental conditions, which are relevant for the clinical in vivo setting, such as pH variations, sampling time, and microbial degradation of Trp and Kyn. The permeabilities of Trp and Kyn are overall similar. However, the permeated Trp/Kyn ratio is generally higher than unity due to endogenous Trp, which should be taken into account to obtain a non-biased Trp/Kyn ratio accurately reflecting systemic concentrations. Additionally, prolonged sampling time is associated with bacterial Trp and Kyn degradation and should be considered in a clinical setting. Finally, the experimental results are supported by the four permeation pathways model, predicting that the hydrophilic Trp and Kyn molecules mainly permeate through lipid defects (i.e., the porous pathway). However, the hydrophobic indole ring of Trp is suggested to result in a small but noticeable relative increase of Trp diffusion via pathways across the SC lipid lamellae, while the shunt pathway is proposed to slightly favor permeation of Kyn relative to Trp.
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