Sweat Samples Research Articles

Characterization of nucleic acids from extracellular vesicle-enriched human sweat

BackgroundThe human sweat is a mixture of secretions from three types of glands: eccrine, apocrine, and sebaceous. Eccrine glands open directly on the skin surface and produce high amounts of water-based fluid in response to heat, emotion, and physical activity, whereas the other glands produce oily fluids and waxy sebum. While most body fluids have been shown to contain nucleic acids, both as ribonucleoprotein complexes and associated with extracellular vesicles (EVs), these have not been investigated in sweat. In this study we aimed to explore and characterize the nucleic acids associated with sweat particles.ResultsWe used next generation sequencing (NGS) to characterize DNA and RNA in pooled and individual samples of EV-enriched sweat collected from volunteers performing rigorous exercise. In all sequenced samples, we identified DNA originating from all human chromosomes, but only the mitochondrial chromosome was highly represented with 100% coverage. Most of the DNA mapped to unannotated regions of the human genome with some regions highly represented in all samples. Approximately 5 % of the reads were found to map to other genomes: including bacteria (83%), archaea (3%), and virus (13%), identified bacteria species were consistent with those commonly colonizing the human upper body and arm skin. Small RNA-seq from EV-enriched pooled sweat RNA resulted in 74% of the trimmed reads mapped to the human genome, with 29% corresponding to unannotated regions. Over 70% of the RNA reads mapping to an annotated region were tRNA, while misc. RNA (18,5%), protein coding RNA (5%) and miRNA (1,85%) were much less represented. RNA-seq from individually processed EV-enriched sweat collection generally resulted in fewer percentage of reads mapping to the human genome (7–45%), with 50–60% of those reads mapping to unannotated region of the genome and 30–55% being tRNAs, and lower percentage of reads being rRNA, LincRNA, misc. RNA, and protein coding RNA.ConclusionsOur data demonstrates that sweat, as all other body fluids, contains a wealth of nucleic acids, including DNA and RNA of human and microbial origin, opening a possibility to investigate sweat as a source for biomarkers for specific health parameters.

Epilepsy and the smell of fear

ObjectiveIn our canine scent detection research involving a specific volatile organic compound (VOC) associated with human epileptic seizure, we began to suspect involvement of the primitive neural networks associated with production of a previously undescribed human alarm pheromone as the origin of our seizure scent. We hypothesized that if we presented fear-scented sweat to our canine seizure scent detection team, and they identified the fear scent as their seizure scent, then that would suggest that they are identical compounds. MethodsFollowing consent and approval, sweat samples taken from volunteers associated with the Brooke Gordon Comprehensive Epilepsy Center at Denver Health were processed by the Canine Assistants (CA) service dog team that had been imprinted to recognize the unique seizure scent from our previous study. In part one, sweat samples were collected from subjects, who had no prior history of epilepsy or seizures, under two different testing environments: watching a scary movie (It) and a neutral/comedy movie (Airplane!). In part two, a larger follow-up study utilizing fear sweat, exercise sweat, epilepsy sweat, and other distractor scents were provided in a multiple choice paradigm to better understand the inter-rater reliability of the canine responses. ResultsIn part one, our canine seizure scent detection team identified fear-scented sweat samples as their seizure scent in 4 of 5 study participants. There was almost perfect agreement of seizure scent detection during fear scent trials between the canine seizure scent detectors with a kappa value of 0.814 (95% CI: 0.668–0.960). In part two, (utilizing eleven different subjects) our canine scent detection team identified samples of either fear or seizure sweat with a sensitivity of 82% and a specificity of 100% (no false positives) from among the multiple choices offered. Additionally, there was 92% agreement between the members of the canine scent detection team. SignificanceWhile this hypothesis testing study is small and deserves replication, it confirms that the Canine Assistants seizure scent detection team consistently and accurately identified fear-scented sweat as their seizure scent, implying that the VOC, menthone, is common to both conditions. This further implies that human seizure propagation and fear network circuitry may share a common anatomy, and that menthone may not only be an early seizure biomarker, but a newly described human alarm pheromone.

Specific sweat metabolite profile in ocular Behcet’s disease

BackgroundBehcet’s disease (BD) is an autoimmune disorder with the serious possibility of blindness, calling for further research on its pathogenesis. Our aim was to study the metabolite composition of sweat in BD and to identify possible biomarkers. MethodsMetabolomics analysis was performed on sweat samples from 20 BD patients and 18 normal controls by liquid chromatography tandem mass spectrometry. ResultsA significantly different metabolic profile of sweat was observed when BD patients were compared with healthy controls. The result of the orthogonal partial least squared-discrimination analysis (OPLS-DA) showed that these two comparison groups could be separated with a relatively satisfactory fitting degree (R2Y = 0.995 and Q2 = 0.817 in positive ion mode; R2Y = 0.991 and Q2 = 0.721 in negative ion mode). Based on OPLS-DA, a panel of metabolites was selected as candidate biomarkers, including l-citrulline, l-pyroglutamic acid, urocanic acid, 2-oxoadipic acid, cholesterol 3-sulfate, and pentadecanoic acid. ConclusionThis is the first report on the metabolite profile of sweat in BD. Our results demonstrated a significantly different metabolite composition of sweat in BD compared to that of healthy controls.

Highly Sensitive and Selective Non-Enzymatic Measurement of Glucose Using Arraying of Two Sweat Sensors Modified By Controlled Growth of Co/Cu and Functionalized Carbon Nanotubes

Due to a relation between glucose in sweat and blood, there is an opportunity to monitor patients' glucose levels non-invasively through sweat. There is a high demand for developing highly selective and sensitive biosensors in order to sense biomarkers like glucose and, therefore, the diseases based on those biomarkers. However, enzymatic sensors are selective to specific biomarkers; they are suffering from high sensitivity to the fluctuation of temperature, oxygen, pH, humidity, detergents, organic reagents, and toxic chemicals, affecting their stability and sensitivity, and reproducibility. Therefore, developing non-enzymatic glucose (or other biomarkers) sensors is getting significant attention to fulfill higher sensitivity and selectivity as well as minimized susceptibility to fouling by enzyme-ageing and adsorbed intermediates. Here we have proposed a combination of two sensors that can help us improve these non-enzymatic sensors' selectivity. Two electrochemical arrayed sensors have been developed. The first electrochemical sensor has been achieved by controlled growth of cobalt nanowire and copper nanoparticles on carbon substrate in order to measure the glucose level at low concentrations, and the second electrochemical sensor has been modified by MWCNT-CO-NH-cyanuric-NH2 and Fe3O4 in order to measure the uric acid and eliminate the interference of it in glucose measurement results. In order to show the morphology of the glucose sensor, the SEM and EDX have been conducted. Also, the FT-IR test has been shown to confirm the functionalization of MWCNT. The electrocatalytic and electrochemical performance of each sensor have been evaluated in the presence of the various contaminants of sweat. The glucose sensor showed less than 5% interference toward ascorbic acid, sodium bicarbonate, and the lactic acid at their max range of presence in the sweat. For eliminating the interference of uric acid, the second sensor has developed, which has no response to the glucose and high sensitivity to the uric acid. The calibration curve of each sensor has been provided in the 3D form, and a simple method of arraying has been applied to improve the sensors' selectivity. The arrayed sensors showed a highly glucose-selective sweat-based sensor with minimized error imposed by the uric acid interference. The glucose sensor's reproducibility and durability have also been tested, which showed less than 5% and 10% variations, respectively. In the end, the arrayed sensor's performance has been evaluated by real sweat samples of a male and a female, analyzed by Clarke’s error grid analysis showing less than 20% deviation from the glucose levels measured by the commercial glucometers.

Osmotic-Capillary Principles for Microfluidic Pumping and Fluid Management for Sweat Sensing Devices

Sweat is an essential biofluid for monitoring individuals’ health as it contains several key biomarkers. However, sampling sweat for analysis is still challenging as most of the commercially available sweat sensing devices are either invasive in nature or work only during active perspiration. These devices may not function under low-sweating conditions and may be incapable of sensing in sweat from sedentary subjects. We demonstrate a new principle for the design of flexible and wearable devices, which are capable of extracting sweat under both resting and actively perspiring conditions using osmotic pressure difference for pumping, and evaporation for liquid disposal (Biomicrofludics, 14, 034112, 2020). The device is composed of silicone, hosting polyacrylamide hydrogel patch, and paper microfluidic conduit with a site of evaporation at the end (evaporation pad). The hydrogel is equilibrated with glycerin, glucose, or NaCl solution to build up the desired osmotic strength to extract fluid from the skin. We investigate their operation using a model biomarker (dye) solution. In-vitro testing with gelatin-based model skin platform revealed that both glucose and glycerin-infused gels facilitate high analyte accumulation on the evaporation pad, with glucose as osmolyte having the highest driving pressure. The cumulative dye collection also depends on the dimensions of the paper channel, hydrogel area and paper porosity. Human trials show potential to extract sweat and analyze it for lactate under both resting and non-resting conditions within a period of two hours. This sweat sampling concept can be integrated in continuously operating wearable devices using enzymatic electrochemical sensors. We used lactate as a concept demonstrator, as sweat appears to be more informative medium for lactate quantification than blood. The ability to measure lactate enables monitoring metabolism and oxidative stress levels in athletes and military personnel.

Gold-silver nanoparticles modified electrochemical sensor array for simultaneous determination of chromium(III) and chromium(VI) in wastewater samples

The oxidation state of ions is a crucial aspect that often has been overlooked when determining the toxicity of chromium (Cr) species in environmental samples. In this study, a novel electrochemical sensor array based on gold-silver nanoparticles modified electrodes was developed for simultaneous determination of the two main chromium species (Cr(III) and (VI)). Specifically, the working electrodes of screen-printed carbon electrodes (SPCEs) were modified with silver-gold bimetallic nanoparticles through electrochemical deposition for detection of Cr(VI). The silver-gold bimetallic nanoparticles were further oxidized to form stable silver-gold bimetallic oxide nanoparticles for the detection of Cr(III). The results showed that the addition of silver with a theoretical value of 1% of gold could contribute to the formation and stabilization of oxides on the surface of gold nanoparticles. After characterization, the two kinds of electrodes were integrated as an electrochemical sensor array for selective and sensitive detection of Cr(VI) and Cr(III). The linear range and limit of detection (LOD, identified by three times of signal-to-noise ratio) were found to be 0.05–5 ppm and 0.1 ppb for Cr(VI), and 0.05–1 ppm and 0.1 ppb for Cr(III), respectively. Finally, the electrochemical sensor array was proven for successful detection of Cr(VI) and Cr(III) in tap water, artificial saliva and artificial sweat samples, and monitoring of Cr(VI) and Cr(III) in chromium-containing wastewater treatment process. Combined with a handheld dual-channel electrochemical device, the simultaneous determination of Cr(VI), Cr(III) and total chromium contents can be easily achieved for various samples.

The Impact of Nutritional Supplementation on Sweat Metabolomic Content: A Proof-of-Concept Study

Sweat is emerging as a prominent biosource for real-time human performance monitoring applications. Although promising, sources of variability must be identified to truly utilize sweat for biomarker applications. In this proof-of-concept study, a targeted metabolomics method was applied to sweat collected from the forearms of participants in a 12-week exercise program who ingested either low or high nutritional supplementation twice daily. The data establish the use of dried powder mass as a method for metabolomic data normalization from sweat samples. Additionally, the results support the hypothesis that ingestion of regular nutritional supplementation semi-quantitatively impact the sweat metabolome. For example, a receiver operating characteristic (ROC) curve of relative normalized metabolite quantities show an area under the curve of 0.82 suggesting the sweat metabolome can moderately predict if an individual is taking nutritional supplementation. Finally, a significant correlation between physical performance and the sweat metabolome are established. For instance, the data illustrate that by utilizing multiple linear regression modeling approaches, sweat metabolite quantities can predict VO2 max (p = 0.0346), peak lower body Windage (p = 0.0112), and abdominal circumference (p = 0.0425). The results illustrate the need to account for dietary nutrition in biomarker discovery applications involving sweat as a biosource.

It’s trust or risk? Chemosensory anxiety signals affect bargaining in women

It is well documented how chemosensory anxiety signals affect the perceiver’s physiology, however, much less is known about effects on overt social behavior. The aim of the present study was to investigate the effects of chemosensory anxiety signals on trust and risk behavior in men and women. Axillary sweat samples were collected from 22 men during the experience of social anxiety, and during a sport control condition. In a series of five studies, the chemosensory stimuli were presented via an olfactometer to 214 participants acting as investors in a bargaining task either in interaction with a fictitious human co-player (trust condition) or with a computer program (risk condition). It could be shown that chemosensory anxiety signals reduce trust and risk behavior in women. In men, no effects were observed. Chemosensory anxiety is discussed to be transmitted contagiously, preferentially in women.

Regional and Time Course Differences in Sweat Cortisol and Glucose During Steady State Exercise

The ability to use sweat as a biofluid for noninvasive sampling and diagnostics is a popular area of innovation. However, body mapping for local sweat metabolites is lacking and collection methods are inconsistent. To determine regional and time course differences in sweat cortisol and glucose concentrations we collected sweat with absorbent patches (3MTMTegaderm+PAD) from eight, non-acclimatized, euhydrated (USG 1.012±0.008) subjects (24-44 y; 80.2±10.2 kg; V̇O2 max 52.2 ±6.4 mL/kg/min) at the following sites: right dorsal forearm (RDF), right triceps (RT), right scapula (RS) and forehead (FH) at 0-25 (25), 30-55 (55), and 60-85 (85) min during 90 min of cycling (82% HR max) in a heated chamber (32°C, 50% RH). ELISA was used for the detection of cortisol (Invitrogen, ThermoFisher Scientific) and glucose (Caymen Chemical Co.) concentrations. Data are presented as mean±SD or median±IQR for data that were not normally distributed. One-way ANOVA or Kruskal-Wallis were used to test differences among groups. Dunn's test for multiple comparisons was used for post-hoc analysis. Excretion rates (ER) were calculated as the product of concentration and local sweat rate (LSR). Whole body sweat rate was 0.85±0.09 mg/cm2/min. LSR was significantly different among sites (FH 4.1±2.3 > RS 1.6±0.6, RDF 1.4±0.9 > RT 0.8±0.5 mg/cm2/min; p<0.0001). LSR was the same across time for FH, whereas RDF (p=0.04), RS (p=0.01), and RT (p=0.01) varied. RS LSR at 55 (p=0.02) and 85 (p=0.02) were greater than 25 min. RT LSR at 55 was higher than 25 min (p=0.01). RDF LSR had no specific differences. Cortisol concentrations were similar across sites (FH 2.7±3.1, RDF 2.2±2.1, RS 2.2±2.2, RT 1.9±1.5 ng/mL). FH cortisol concentrations varied across time (1.8±1.6, 2.9±2.2, 4.9±9.6 ng/mL at 25, 55, and 85 min, respectively; p=0.02), with specific differences between 25 and 85 min (p=0.02). RDF cortisol concentrations also varied across time (1.3±1.6, 2.9±1.7, 3.5±6.3 ng/mL at 25, 55, and 85 min, respectively; p=0.01), with specific differences between RDF 25 and 85 min (p=0.01). RT and RS cortisol concentrations were similar across time. Cortisol ER was 4.3±6.2 pg/cm2/min and varied across sites (FH 9.8±14.8, RDF 3.7±4.9, RS 4.0±3.1, RT 2.2±2.2 pg/cm2/min (p<0.0001)). FH cortisol ER was greater than all other sites (RDF p=0.004, RS p=0.006, RT p<0.0001). FH (p=0.02) and RDF (p=0.01) cortisol ERs varied across time points, where 85 was greater than 25 min (FH p=0.02, RDF p=0.01). RT and RS cortisol ERs were similar across time. Glucose concentrations (0.2±0.5 mg/dL) were similar across sites and between time points within the same site. Glucose ER across all sites was 5.2±9.1 ng/cm2/min and differed across sites (FH 5.4±22.4, RDF 6.2±9.9, RS 7.0±8.6, RT 2.8±4.1 ng/cm2/min; p=0.04), where FH was greater than RT (p=0.03). Glucose ER did not differ between time points within each location. In summary, cortisol concentration and ER increase as exercise time progresses on the FH and RDF, but not the RS or RT. This study demonstrates that the site and time point selection for sweat sampling is a necessary consideration for future research.

A review of wearable biosensors for sweat analysis.

Recent advances in the skin-interfaced wearable sweat sensors allow a personalized daily diagnosis and prognosis of the diseases in a form of a non-invasive, portable, and continuous monitoring system. Especially, the soft microfluidic system provides robust quantitative analysis platforms that integrate sweat sampling, storing, and various sensing capabilities. This review systematically introduces the sweat collecting mechanism using soft microfluidic valves, including calculation of sweat storage and loss. In terms of sweat analysis, colorimetric (e.g. enzymatic, chemical, or their mixed reactions), electrochemical (e.g. voltammetric, potentiometric, amperometric, or conductometric), and multiplex measurements of sweat contents facilitate diagnosis of diseases via analysis of combined multiple data, such as vital signals (e.g. ECG, EMG, EEG, etc.) and information from the skin (e.g. temperature, GSR, etc.). The integration of wireless communication with the microfluidic systems enables point-of-care health monitoring for disease and specific physiological status.

Use of reduced graphene oxide for sensitive determination of sulfanilamide in synthetic biological fluids and environmental samples by batch injection analysis

In this work, a reduced graphene oxide sensor associated to the batch injection analysis system with amperometric detection was investigated for the simple, fast and sensitive monitoring of sulfanilamide in lake water and synthetic biological fluid (saliva, sweat and urine) samples. The modified sensor showed a potential displacement of 170 mV and an increase in peak current of 5.5-fold for the electrochemical oxidation of sulfanilamide in comparison to the bare electrode, resulting in a highly sensitive and selective method. Besides, the developed method showed excellent analytical performance with a limit of detection of 2.30 µmol L−1, linear range from 10 to 50 µmol L−1, relative standard deviation below 5.6%, and recovery ranges varying from 83 to 109% for the analysis of spiked samples. In addition, the minimum sample preparation (simple dilution) combined with a high analytical frequency (130 analyses per hour) can be highlighted. Thus, the proposed method demonstrates to be a promising analytical tool for the implementation in routine analysis of clinical interest and environmental monitoring in loco.

A flexible and wearable epidermal ethanol biofuel cell for on-body and real-time bioenergy harvesting from human sweat

Flexible and wearable epidermal biofuel cells (BFCs) that are worn on skin for the direct electricity generation from human perspiration are perceived to be a most enticing and promising next-generation energy source for addressing the on-body energy-harvesting challenge of wearable electronics. Previously reported epidermal BFCs are only focused on the utilization of human endogenous substances ( i.e ., glucose or lactate that can be produced by human body) in sweat as the biofuels for power production. Given the substances diversity in human body, some exogenous substances (that cannot be produced by body) are abundant in sweat in certain daily situations, however, their utility for epidermal bioenergy harvesting has been ignored so far. In the present work, we propose the first example of a flexible and wearable epidermal microfluidic human exogenous substance ethanol/oxygen BFC for the simultaneous sweat sampling and sweat bioelectricity generation on skin of individuals who drink alcohol. Certain actual situations that were associated with alcohol absorption and elimination in human body were considered and investigated for skin-on, continuous in situ sweat ethanol bioenergy generation in controlled environments. Such non-invasive flexible and wearable epidermal ethanol BFC expands the scope of human sweat-derived biofuels from endogenous substances to exogenous ones and holds great promise for the skin-worn and real-time bioenergy harvesting from human perspiration, which may open up a new challenge and approach to explore the human sweat for bioenergy conversion. We demonstrated the first example of a flexible and wearable epidermal microfluidic human exogenous substance ethanol/oxygen biofuel cell through a skin-worn, real-time in situ fashion to harvest the continuous electrical power from alcohol drinkers’ perspiration in different real-life scenarios. • The first example of a flexible and wearable epidermal human exogenous substance ethanol biofuel cell. • The simultaneous sweat sampling and sweat bioelectricity generation on skin of individuals who drink alcohol. • Certain actual situations were considered and investigated for skin-on, continuous in situ sweat ethanol bioenergy generation.

Role of sweat ion ratios in diagnosing cystic fibrosis.

Sweat chloride (Cl- ) concentration is the gold standard for diagnosing cystic fibrosis (CF). This is, however, challenging among patients with borderline values. Previous studies have reported that the sweat Cl- /Na+ ratio may be useful for diagnosing CF; however, little is known about Cl- /K+ and (Cl- + Na+ )/K+ ratios. This study aimed to retrospectively define the most appropriate outcome of the sweat test. Samples of sweat were collected using the Gibson and Cooke method. Cl- , Na+ , and K+ were further quantified in 2084 participants-1283 CF and 801 non-CF-based on clinical diagnosis. Among those with borderline sweat Cl- values (n = 502), 34.8% had CF. In the receiver operating characteristic curve analysis, the area under the curve was calculated to evaluate the diagnostic value of the ion ratios. In the overall population, all the ratios significantly discriminated CF from non-CF, whereas in the borderline group, only Cl- /Na+ significantly discriminated CF and non-CF subjects, regardless of age.

Administration of pilocarpine by microneedle patch as a novel method for cystic fibrosis sweat testing.

The sweat test is the gold standard for the diagnosis of cystic fibrosis (CF). The test utilizes iontophoresis to administer pilocarpine to the skin to induce sweating for measurement of chloride concentration in sweat. However, the sweat test procedure needs to be conducted in an accredited lab with dedicated instrumentation, and it can lead to inadequate sweat samples being collected in newborn babies and young children due to variable sweat production with pilocarpine iontophoresis. We tested the feasibility of using microneedle (MN) patches as an alternative to iontophoresis to administer pilocarpine to induce sweating. Pilocarpine‐loaded MN patches were developed. Both MN patches and iontophoresis were applied on horses to induce sweating. The sweat was collected to compare the sweat volume and chloride concentration. The patches contained an array of 100 MNs measuring 600 μm long that were made of water‐soluble materials encapsulating pilocarpine nitrate. When manually pressed to the skin, the MN patches delivered >0.5 mg/cm2 pilocarpine, which was double that administered by iontophoresis. When administered to horses, MN patches generated the same volume of sweat when normalized to drug dose and more sweat when normalized to skin area compared to iontophoresis using a commercial device. Moreover, both MN patches and iontophoresis generated sweat with comparable chloride concentration. These results suggest that administration of pilocarpine by MN patches may provide a simpler and more‐accessible alternative to iontophoresis for performing a sweat test for the diagnosis of CF.

The effect of short and continuous absorbent patch application on local skin temperature underneath

Objective. By attaching absorbent patches to the skin to collect sweat, an increase in local skin temperature (T sk) underneath the patches seems unavoidable. Yet this effect has not been quantified. The present study investigates the effect of absorbent patch application on local T sk underneath. Approach. Ten healthy participants cycled for 60 min at an exercise intensity relative to their body surface area (40 W.m−2) in three environmental conditions (temperate: 25 °C 45% RH, hot-humid: 33 °C 65% RH and hot-dry: 40 °C 30% RH). The effect of short sweat sampling (i.e. from min 25–30 to min 55–60) on T sk was examined on the right scapula. T sk of the left scapula served as control. The effect of continuous sweat sampling (i.e. four consecutive 15 min periods) on T sk was examined on the right upper arm. T sk of the left upper arm served as control. Main results. Neither short nor continuous application of absorbent sweat patches affected T sk underneath the patches in the hot-humid and hot-dry condition (P > 0.05). In the temperate condition, continuous application led to a significant increase in T sk underneath the patches during the first and second minute. This increase remained throughout the experiment (1.8 ± 0.6 °C; P < 0.001). Short application of sweat patches did not affect the local T sk underneath (P > 0.05) in the temperate condition. Significance. To avoid a significant increase in local T sk underneath sweat patches, continuous application should be prevented in, especially, a temperate condition. Timely removal of sweat patches should be taken into account during longer periods of collecting sweat in field or laboratories settings.

Electrochemical biosensor for glycine detection in biological fluids

We present herein the very first amperometric biosensor for the quantitative determination of glycine in diverse biological fluids. The biosensor is based on a novel quinoprotein that catalyzes the oxidation of glycine with high specificity. This process is coupled to the redox conversion of Prussian blue in the presence of hydrogen peroxide originating from the enzymatic reaction. The optimized tailoring of the biosensor design consists of the effective encapsulation of the quinoprotein in a chitosan matrix with the posterior addition of an outer Nafion layer, which is here demonstrated to suppress matrix interference. This is particularly important in the case of ascorbic acid, which is known to influence the redox behavior of the Prussian blue. The analytical performance of the biosensor demonstrates fast response time (<7 s), acceptable reversibility, reproducibility, and stability (<6% variation) as well as a wide linear range of response (25–500 μM) that covers healthy (and even most unhealthy) physiological levels of glycine in blood/serum, urine and sweat. A total of 6 real samples from healthy patients and animals were analyzed: two serum, two urine and two sweat samples. The results were validated via commercially available fluorescence kit, displaying discrepancy of less than 9% in all the samples. The unique analytical features and effortless preparation of the new glycine biosensor position it at the forefront of current technologies towards decentralized clinical applications and sport performance monitoring.

Major urinary protein excreted in rodent hindpaw sweat.

Alternative roles for sweat production beyond thermoregulation, considered less frequently, include chemical signaling. We identified the presence of a well-established rodent urinary pheromone, major urinary protein (MUP) in sweat ductules of the footpad dermal skin of mice. A hindpaw sweat proteomic analysis in hindpaw sweat samples collected in rats and generated by unmyelinated axon activation, identified seven lipocalin family members including MUP and 19 additional unique proteins. Behavioural responses to sniffing male mouse foot protein lysates suggested avoidance in a subset of male mice, but were not definitive. Rodent hindpaw sweat glands secrete a repertoire of proteins that include MUPs known to have roles in olfactory communication.

Screening of some banned aromatic amines in textile products from Indian bandhani and gamthi fabric and in human sweat using micellar liquid chromatography

Certain dyes in textile products, which are capable of reductively splitting into carcinogenic aromatic amines, are strictly controlled in many countries. A simple, rapid, sensitive and green chromatographic method has been developed and validated for the simultaneous determination of 4-aminophenol (4-AMP), p-phenylenediamine (p-PPD) and benzidine (BNZ), banned aromatic amines in dyeing clothes and human sweat. The separation was achieved using a micellar mobile phase of 0.1 M SDS, 4% 1- butanol (v/v) buffered to pH 7 with sodium dihydrogen phosphate, flowing under isocratic mode at 1 mL/min through a C18 column. Photodiode array detector was set at 210 nm. Using the above chromatographic conditions, 4-AMP, p-PPD and BNZ were eluted at 3.5 min, 4.7 min. and 5.4 min., respectively, adequately resolved. The method was validated by Standard Practices for Method Validation in Forensic Toxicology guideline for the industry in terms of selectivity, calibration curve, linearity (r2 = 0.999), trueness (relative bias, −3.5 to 7%) precision (relative standard deviation, <8.5%), and robustness of selected compounds. This method was sensitive enough for the routine analysis of aromatic amine in textile material with limit of detection in the (0.01 to 0.04 μg/mL range and limit of quantification (0.03–0.13 μg/mL). The method was successfully applied to dyed clothes and sweat samples. The main advantage of the developed method is the easy extraction step of the analytes from incurred samples without any further cleanup, which reduces per sample analysis cost and the total time of analysis. The developed method could easily replace regular chromatographic technique used for their detection.

Printed Iontophoretic‐Integrated Wearable Microfluidic Sweat‐Sensing Patch for On‐Demand Point‐Of‐Care Sweat Analysis

AbstractIn recent years, wearable epidermal sweat sensors have received extensive attention owing to their great potential to provide personalized information on the health status of individuals at the molecular level. For on‐demand medical analysis of sweat in sedentary conditions, a cost‐effective wearable integrated platform combining sweat stimulation, sampling, transport, and analysis is highly desirable. In this work, a printed iontophoretic system integrated into a microfluidic sensing platform, which combines sweat induction, collection, and real‐time analysis of sweat‐ions into a single patch for on‐demand sweat monitoring on human subjects in stationary conditions is reported. The incorporation of microfluidics features facilitates sweat sampling, collection, and guiding through capillary effect. The multisensing sensor array exhibits sensitivity close to Nernstian behavior for sodium, potassium, and pH. The correlation between the concentrations of ions measured with the sweat patch and with ion chromatography analysis demonstrates the applicability of the system for real‐time point‐of‐care monitoring of the health status of individuals. Furthermore, the sweat patch electronic interface with wireless transmission enables real‐time data monitoring and storage over a cloud platform. This printed iontophoretic‐integrated fluidic sweat patch provides a cost‐effective solution for the on‐demand analysis of sweat components for healthcare applications.

Gold coated electrospun polymeric fibres as new electrode platform for glucose oxidase immobilization

Fibres of poly(methyl methacrylate) were obtained by electrospinning, subjected to coating with a gold layer and then attached on a thin polyethylene terephthalate substrate in order to obtain flexible electrodes for biosensing applications. The morphology of these electrodes, investigated by scanning electron microscopy showed multi-layers of random oriented fibres of approx. 400 nm diameter. The electrochemical characterization of these flexible electrodes was performed by cyclic voltammetry and electrochemical impedance spectroscopy in acid and neutral media, in the absence and in the presence of redox probes, proving their superior performance (e.g. 5-fold current density value) when compared to planar gold electrodes obtained on silicon wafers. The electrodes obtained from conductive electrospun polymeric fibres nets were tested by cyclic voltammetry and amperometry for the detection of hydrogen peroxide with a sensitivity of 0.84 mA cm−2 mM−1 and a detection limit of 20.40 μM. The immobilization of the model enzyme glucose oxidase at the surface of the gold-coated electrospun polymeric fibres electrode was investigated and the obtained biosensor was applied for glucose determination in aqueous solutions by fixed potential amperometry with a sensitivity of 3.10 μA cm−2 mM−1, a detection limit of 0.33 mM, and reduced interferences. Also, the practical applicability of the biosensor was tested for the detection of glucose in artificial sweat and serum samples.