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Bacteria induced pH changes in tissue-engineered human skin detected non-invasively using Raman confocal spectroscopy
摘要： Skin has a highly regulated pH environment of around pH 7.2 but with an acid barrier mantle of around pH 5.5. Trauma, inflammation, and infection are all thought to disrupt this pH environment but the lack of a non-invasive technique to measure pH within discrete locations within skin has hindered investigating what role pH plays in wound healing. In this study, a confocal Raman microspectroscopy method was used for measuring pH in a 3D tissue engineered model of human skin (TE-skin) and evaluated for its ability to detect changes in pH in response to wounding, inflammation and bacterial infection. The state of protonation of phosphate groups within the TE-skin was used to indicate pH in a non-destructive manner exploring depths of skin from the stratum corneum to 600 microns into the dermis. Deliberate wounding or inflammation (induced by IL-17) resulted in a loss of the acid mantle. Detailed scanning of TE-skin infected with Staphylococcus aureus or Pseudomonas aeruginosa revealed heterogeneous pH microenvironments ranging in size from 10 (cid:1) 10 to 50 (cid:1) 100 microns and ranging from pH 5 to 9. These microenvironments were not detected if an average pH for the TE-skin model was used.
关键词： bacteria,tissue-engineered,skin,pH
更新于2025-11-21 11:24:58
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Matrix-Independent Highly Conductive Composites for Electrodes and Interconnects in Stretchable Electronics
摘要： Electrically conductive composites (ECCs) hold great promise in stretchable electronics due to their printability, facile preparation, elasticity, and possibility for large area fabrication. A high conductivity at steady state and during mechanical deformation is a critical property for ECCs, and extensive efforts have been made to improve the conductivity. However, most of those approaches are exclusively functional to a specific polymer matrix, restricting their capability to meet other requirements such as the mechanical, adhesive and thermomechanical properties. Here we report a generic approach to prepare ECCs with conductivity close to that of bulk metals and maintain their conductivity during stretching. This approach iodizes the surfactants on the commercial silver flakes, and subsequent photo exposure converts these silver iodide nanoparticles to silver nanoparticles. The ECCs based on silver nanoparticles-covered silver flakes exhibit high conductivity because of the removal of insulating surfactants as well as the enhanced contact between flakes. The treatment of silver flakes is independent of the polymer matrix and provides the flexibility in matrix selection. In the development of stretchable interconnects, ECCs can be prepared with the same polymer as the substrate to ensure strong adhesion between interconnects and the substrate. For the fabrication of on-skin electrodes, a polymer matrix of low modulus can be selected to enhance conformal contact with the skin for reduced impedance.
关键词： conductive composites,human-machine interface,on-skin electronics,electrophysiological monitoring,iodization,silver nanoparticles,silver flakes
更新于2025-11-14 17:28:48
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Translating chemometric analysis into physiological insights from in vivo confocal Raman spectroscopy of the human stratum corneum
摘要： The superficial layer of the skin, the stratum corneum (SC), consists of corneocytes surrounded by lipid regions and acts as a protective barrier for the body against water loss, toxic agents and microorganisms. As most substances permeate the stratum corneum through the lipid regions, lipid organization is considered crucial for the skin barrier function. Here, we investigate the potential of in vivo confocal Raman spectroscopy to describe the composition and organization of the SC. Confocal Raman spectroscopy is finding increasing use in the characterization of skin in biomedical, pharmaceutical and cosmetic applications. In this work, we analyze the spectra using chemometric methods and obtain principal components that correspond to the primary skin constituents: protein (keratin), natural moisturizing factor (NMF), water and lipid contributions in both ordered (orthorhombic) and disordered structural organization. By identifying these important components of the SC, these results highlight the utility of this in vivo, non-invasive, and depth resolved tool at the forefront of skin research.
关键词： Skin barrier,Natural moisturizing factor,Multivariate curve resolution,Keratin,Lipid organization
更新于2025-11-14 15:16:37
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Topical treatment with oleocanthal extract in reducing inflammatory reactions after photodynamic therapy: a prospective quasi-experimental pilot study
摘要： Objective: Photodynamic therapy (PDT) is an effective treatment against skin field cancerization. Its main side effect is local inflammation in the treated area. The phenolic compound oleocanthal (decarboxy methyl ligstroside aglycone), which is present in extra virgin olive oil (EVOO), has anti-inflammatory properties. The purpose of this study was to evaluate the topical efficacy of an oily fluid enriched with oleocanthal (OC) extract, in comparison with a conventional oily fluid, in reducing the degree of inflammatory reaction after conventional PDT. Methods: Quasi-experimental pilot study, before-after with a control group, performed with a cohort of consecutive patients diagnosed with actinic keratosis/field cancerization (AK/FC) in the forehead and/or scalp, treated by PDT. The study was carried out from April 2016 to November 2017 at a speciality hospital in southern Spain. A group of 24 consecutive patients received the topical application, three times daily for one week, of an emollient oily fluid in the area treated with PDT. Subsequently, another group, of 23 consecutive patients, received the same treatment pattern with an oily fluid enriched with OC extract. The post-PDT inflammatory reaction was measured by an independent member of the hospital's dermatology department, using the following visual scale of erythema (from 0 to 4). The assessment was conducted at 30 min and at 48 h post-PDT. Results: In the assessment at 48 h after treatment, the inflammation had improved more among the patients treated with OC (median: 25%, 95%CI: -5.3 to 28.5) than in the non-OC group (median: 0%; 95%CI: -45.2 to -6.2). The difference was statistically significant (p < 0.01), and the Cohen's d value was 0.89 (large effect). At three months after PDT, a complete response had been obtained by 60.9% of the patients treated with OC compared to 29.2% of the non-OC group, and the difference was close to statistical significance (p=0.059). Conclusions: The topical application of an oily fluid enriched with OC extract achieved a greater reduction in post-PDT cutaneous inflammation and a better treatment response, in comparison with the application of a conventional oily fluid.
关键词： Skin barrier,Oleocanthal,Emulsions,Virgin olive oil,Skin physiology,Photodynamic therapy
更新于2025-09-23 15:23:52
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The ablative fractional coagulation zone influences skin fluorescence intensities of topically applied test molecules-An in vitro study with fluorescence microscopy and fluorescence confocal microscopy
摘要： Background: Ablative fractional laser (AFL) increases uptake of topically applied skin agents. The coagulation zone (CZ) surrounding vertically ablated channels may influence uptake of drugs. Objectives: To investigate impact of CZ thickness on skin fluorescence intensities (FI) of a hydrophilic molecule by means of fluorescence microscopy (FM) and fluorescence confocal microscopy (FCM). Second, to compare FI of hydrophilic and lipophilic test molecules by FCM. Study Design/Methods and Materials: Microchannels with CZ thicknesses of 0, 20, and 80 μm were generated by microneedles or AFL (10,600 nm). Channels were 700 μm deep and number of channels kept constant per skin area. After 4 hours of incubation, FI induced by sodium fluorescein (NAF, hydrophilic, logarithmic partition-coefficient (logP) = -1.52, MW = 376.26) were quantified in both CZ and surrounding skin by FM (0–1,500 μm) and FCM (0–90 μm). FI of NAF and carboxyfluorescein (CAF, lipophilic, logP = 2.9, MW = 376.32) were compared by FCM. Results: By FM, NAF-induced FI were higher in CZ than in surrounding skin (P ≤ 0.001). Highest NAF-FI were induced in skin pretreated with a thin CZ (CZ–20 μm), assessed by both FM and FCM and in particular, FI were higher than in skin pretreated with no CZ (CZ–0 μm) (FM P ≤ 0.041, FCM P < 0.012). Skin FI remained constant to a depth of 500 μm, which corresponded to approximate depth of microchannels (CZ–0 μm, CZ–20 μm, CZ–80 μm: 0–500 μm P ≥ 0.107). In accordance with FM data, FCM showed higher FI within CZ than in surrounding skin, but gradually decreased to zero at a depth of 90 μm. NAF-FI were higher than CAF-FI (P ≤ 0.036), and highest CAF-FI were induced by CZ–0 μm and CZ–20 μm compared to CZ–80 μm (P ≤ 0.009). Conclusions: The influence of the CZ thickness on skin FI differs between small hydrophilic and lipophilic test molecules. Results may have clinical relevance for laser-assisted drug delivery.
关键词： sodium fluorescein,reflectance,carboxyfluorescein,dermatology,drug delivery,skin imaging
更新于2025-09-23 15:23:52
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Skin friction measurements on structured surfaces using Clauser-chart method and Oil film interferometry
摘要： Measurements of skin friction have been performed on flat and hexagonal concave surfaces using the conventional Clauser-chart method and the Oil film interferometry. The values of shear stress coefficients measured by the conventional Clauser-chart method on a flat plate were found to be up to 13 % higher from the ones deduced by the Oil film interferometry. The velocity profiles required for the Clauser-chart were obtained by using hot wire anemometry. The analysis of the results suggested that the conventional Clauser-chart method cannot be used to predict shear stresses acting on the hexagonal concave surfaces due to the existence of strong pressure gradients. Oil film interferometry not only provides accurate and direct values of shear stress coefficients but also helps to visualize the flow above the surface.
关键词： Oil film interferometry,skin friction,Clauser-chart
更新于2025-09-23 15:23:52
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Absolute quantification (ml blood/sec???mm2 tissue) of normal vs. diabetic foot skin microvascular blood perfusion: Feasibility of FM-PPG measurements under clinical conditions
摘要： Fluorescence-mediated photoplethysmography (FM-PPG) is the first routine clinical methodology by which to quantifiably measure tissue blood perfusion in absolute terms (mL blood/sec ? mm2 tissue). The FM-PPG methodology has been described in detail previously in this journal (MVR 114, 2017, 92-100), along with initial proof-of-concept measurements of blood perfusion in both ocular and forearm skin tissues. The motivation for the current study was to investigate whether FM-PPG can be used readily and routinely under realistic clinical conditions. The vehicle for doing this was to measure medial foot capillary blood flow, i.e., tissue perfusion, in 7 normal subjects, mean = 6.76 ± 2.29 E-005 mL/(sec ? mm2), and lesion-free areas of 8 type-2 diabetic patients with skin ulceration, mean = 4.67 + 3.15 E-005 mL/(sec ? mm2). Thus, perfusion in the diabetics was found to be moderately lower than that in the normal control subjects. Earlier skin perfusion measurements in medial forearms of 4 normal subjects, mean = 2.64 + 0.22 E-005 mL/(sec ? mm2), were lower than both the normal and diabetic foot perfusion measurements. Variability in the heartbeat-to-heartbeat blood perfusion pulses in the skin capillaries, defined as the ratio of the standard deviation among beat-to-beat pulses divided by the mean perfusion of those pulses, was determined for each subject. Average variability in foot skin was 21% in the diabetic population, versus 16% for normal subjects; and it was 18% in forearm skin. We conclude that absolute quantitative FM-PPG measurement of skin blood perfusion at the level of nutritive capillaries is feasible routinely under clinical conditions, allowing for quantitative measurement of skin tissue blood perfusion in absolute terms.
关键词： Indocyanine green dye,Type-2 diabetes,Fluorescence-mediated photoplethysmography,Foot skin blood perfusion,Absolute quantification
更新于2025-09-23 15:23:52
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Ultraviolet light-related DNA damage mutation signature distinguishes cutaneous from mucosal or other origin for head and neck squamous cell carcinoma of unknown primary site
摘要： Background: Head and neck squamous cell carcinoma of unknown primary site (HNSCCUP) is a diagnostic challenge. Identification of an ultraviolet (UV) light-related DNA damage signature using next-generation sequencing (NGS) can classify the primary site of origin as cutaneous. Methods: A 62-year-old male was seen with 2 months of left neck swelling. He was a lifetime nonsmoker but had a history of cutaneous squamous cell carcinoma (SCC) of the left helix. He was also found to have left hilar adenopathy. He had a p16-negative HNSCCUP on fine needle aspiration (FNA) biopsy of the left neck. Results: NGS of the FNA specimen revealed a high number of somatic mutations that were mostly C to T transitions, indicating a UV mutation signature and confirming the diagnosis of cutaneous SCC. Conclusions: Identification of a UV DNA damage signature with NGS distinguishes HNSCCUP of cutaneous vs mucosal or other squamous cell carcinoma origin.
关键词： unknown primary squamous cell carcinoma of head and neck,cutaneous tumor mutation burden,next-generation sequencing,ultraviolet light-related DNA damage signature,skin cancer
更新于2025-09-23 15:23:52
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Forensic 3D documentation of skin injuries using photogrammetry: photographs vs video and manual vs automatic measurements
摘要： Accurate and precise documentation of lesions is an important aspect of the forensic pathologists’ work. Photogrammetry provides a useful tool to take precise measurements from photographs. These photographs are normally acquired with single camera photographs, but the procedure is quite time-consuming. Video recording has the potential to record a larger amount of image data faster. We documented 33 cadaveric skin lesions, using photographs and video recordings. The dimensions of the lesions ranged between 0.27 and 21.8 cm. The measurements of the lesions were extracted with both manual and automatic point measurements from photographs and from video frames, respectively. Very small differences (mean and median < 1 mm) were found between measurements taken in photographs versus video frames. Video frames were often blurred, preventing clear demarcation of the edges of the lesions and presenting a larger amount of noise in the 3D models. The differences between the manual point and automatic point measurements were very small (mean and median < 1 mm), but the manual procedure is to be preferred, since automatic points were not always located on the edges of the lesions. The only aspect in which video frames were superior to photographs was the recording time: video recording was almost five times faster than the photo sessions. In conclusion, this study shows that precise and comparable measurements can be extracted both from photographs and video frames. The video is the fastest method, but the use of photographs is still recommended. Manual measurements are more precise than automatic measurements and equally time-consuming.
关键词： Skin injuries,Video documentation,Photogrammetry,3D documentation
更新于2025-09-23 15:23:52
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Organic Field-Effect Transistor Based Ultrafast, Flexible, Physiological Temperature Sensors with Hexagonal Barium Titanate Nanocrystals in Amorphous Matrix as Sensing Material.
摘要： Organic field-effect transistors (OFETs) with hexagonal barium titanate nanocrystals in amorphous matrix (h-BTNC) as one of the bilayer dielectric system have been fabricated on a highly flexible 10 μm thick polyethylene terephthalate (PET) substrates. The device current and mobility remains same upto a bending radius of 4mm that make it suitable for wearable e-skin applications. h-BTNC films found to be highly temperature sensitive and the OFETs designed based on this material showed ultra-precession (~4.3 mK), low power (~ 1μW at 1.2 V operating voltage), ultrafast response (~24 ms) in sensing temperature over a range from 20 °C to 45 °C continuously. The sensors are highly stable around body temperature and work at various extreme conditions, such as under water, solutions of different pH as well as of various salt concentrations. These properties make this sensor very unique and highly suitable for various healthcare and other applications, where in a small variation of temperature around this temperature range is required to be measured at an ultra-fast speed.
关键词： low power OFETs,electronic skin,temperature sensors,organic field-effect transistors,flexible sensors,healthcare sensors
更新于2025-09-23 15:23:52