A Real-Time Detection Device for the Rapid Quantification of Skin Casual Sebum Using the Oil Red O Staining Method.

The human skin sebum suggests that it (along with other epidermal surface lipids) plays a role in skin barrier formation, the moderation of cutaneous inflammation, and antimicrobial defense. Various methods have been developed for collecting and measuring skin sebum. We tested methods of detection using "color intensity", by staining the skin casual sebum. This process was conducted in three steps; first, the selection of materials for sebum collection; second, staining the collected sebum; third, the development of a device that can measure the level of stained sebum. A plastic film was used to effectively collect sebum that increased with the replacement time of the sebum. In addition, the collected sebum was stained with Oil Red O (ORO) and checked with RGB; as a result, the R2 value was higher than 0.9. It was also confirmed that the correlation value was higher than 0.9 in the comparison result with Sebumeter®, which is a common standard technology. Finally, it was confirmed that the R2 value was higher than 0.9 in the detection value using the sensor. In conclusion, we have proven the proof of concept (PoC) for this method, and we would like to introduce an effective sebum measurement method that differs from the existing method.

Pentacyanoammineferrate-Based Non-Enzymatic Electrochemical Biosensing Platform for Selective Uric Acid Measurement.

The electrochemical-based detection of uric acid (UA) is widely used for diagnostic purposes. However, various interfering species such as ascorbic acid, dopamine, and glucose can affect electrochemical signals, and hence there is an outstanding need to develop improved sensing platforms to detect UA with high selectivity. Herein, we report a pentagonal mediator-based non-enzymatic electrochemical biosensing platform to selectively measure UA in the presence of interfering species. The working electrode was fabricated by electrodepositing polymerized 1-vinylimidazole (PVI), which has an imidazole ligand, onto indium tin oxide (ITO), and then conjugating nickel ions to the PVI-coated ITO electrode. Electrode performance was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements and integrated together with pentacyanoammineferrate, which can bind to the amine groups of UA and function as an electron transferring mediator. The experimental results showed a wide linear range of UA concentration-dependent responses and the multi-potential step (MPS) technique facilitated selective detection of UA in the presence of physiologically relevant interfering species. Altogether, these findings support that pentacyanoammineferrate-based non-enzymatic electrodes are suitable biosensing platforms for the selective measurement of UA, and such approaches could potentially be extended to other bioanalytes as well.

Stretchable Fiber Biofuel Cell by Rewrapping Multiwalled Carbon Nanotube Sheets.

The fiber-type biofuel cell is attractive as an implantable energy source because the fiber can modify various structures and the wound can be stitched like a suture. In addition, in daily life, the biofuel cell is forced by human motion, and stretchability is a critical requirement for real applications. Therefore, we introduce a new type of highly stretchable, stable, soft fiber biofuel cell with microdiameter dimensions as an energy harvester. The completed biofuel cell operated well in fluids similar to human fluids, such as 20 mM phosphate-buffered 0.14 M NaCl solution (39.5 mW/cm2) and human serum (36.6 µW/cm2). The fiber-type biofuel cell can be reversibly stretched up to 100% in tensile direction while producing sustainable electrical power. In addition, the unique rewrapping structure, which traps the enzyme between multiwalled carbon nanotube sheets, enormously enhanced the stability of the biofuel cell when the biofuel cell was repeatedly stretched (the power density retention increased from 63 to 99%) and operated in human serum (the power density retention increased from 29 to 86%). The fiber can be easily woven into various structures, such as McKibben braid yarn, and scaled up by series and parallel connections.

A Simple Interfacial Platform for Homogeneous Electrochemical Immunoassays Using a Poly(Vinylimidazole)-Modified Electrode.

In this study, a homogeneous method featuring simple, one-step detection was developed to analyze hippuric acid (HA), a major metabolite of toluene. High sensitivity was achieved with the facile immobilization of poly(vinylimidazole) (PVI) on an indium tin oxide (ITO) electrode. Using a previously developed approach, pentacyanoferrate was coordinated with pyridyl-N ligands, and the redox-active Fe(II/III) centers were bound to Ni(II) ions on the electrode via electrostatic cyanide bridges. The detection was accomplished by the competitive binding of free HA and pentacyanoferrate-(4-aminomethylpyridine-hippuric acid) (Fe-HA, the electron transfer mediator) to the HA antibody on the Ni(II) ions-modified PVI-ITO (Ni-PVI-ITO) electrode. The electrical and physicochemical characterization of the electrode was carried out by cyclic voltammetry, differential pulse voltammetry, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. At low mediator concentrations, the electrical signals were proportional to the HA concentration between 0.1 µg/mL and 1.0 mg/mL. The same method may be extended to other small organic molecules.

Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes.

Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)2/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0-1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0-10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA) or ascorbic acid (AA). Therefore, this approach allowed the development of a simple, disposable glucose biosensor.

Assurance of mitochondrial integrity and mammalian longevity by the p62-Keap1-Nrf2-Nqo1 cascade.

Sqstm1/p62 functions in the non-canonical activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2). However, its physiological relevance is not certain. Here, we show that p62(-/-) mice exhibited an accelerated presentation of ageing phenotypes, and tissues from these mice created a pro-oxidative environment owing to compromised mitochondrial electron transport. Accordingly, mitochondrial function rapidly declined with age in p62(-/-) mice. In addition, p62 enhanced basal Nrf2 activity, conferring a higher steady-state expression of NAD(P)H dehydrogenase, quinone 1 (Nqo1) to maintain mitochondrial membrane potential and, thereby, restrict excess oxidant generation. Together, the p62-Nrf2-Nqo1 cascade functions to assure mammalian longevity by stabilizing mitochondrial integrity.

Heterogeneous electrochemical immunoassay of hippuric acid on the electrodeposited organic films.

By directly coordinating hippuric acid (HA) to the ferrate (Fe) as an electron transfer mediator, we synthesized a Fe-HA complex, which shows a good electrochemical signal and thus enables the electrochemical immunoanalysis for HA. We electrodeposited organic films containing imidazole groups on the electrode surface and then bonded Ni ion (positive charge) to induce immobilization of Fe-HA (negative charge) through the electrostatic interaction. The heterogeneous competitive immunoassay system relies on the interaction between immobilized Fe-HA antigen conjugate and free HA antigen to its antibody (anti-HA). The electric signal becomes weaker due to the hindered electron transfer reaction when a large-sized HA antibody is bound onto the Fe-HA. However, in the presence of HA, the electric signal increases because free HA competitively reacts with the HA antibody prior to actual reaction and thus prevents the HA antibody from interacting with Fe-HA at the electrode surface. This competition reaction enabled an electrochemical quantitative analysis of HA concentration with a detection limit of 0.5 µg mL(-1), and thus allowed us to develop a simple and rapid electrochemical immunosensor.

Homogeneous electrochemical detection of hippuric acid in urine based on the osmium-antigen conjugate.

A homogeneous electrochemical immunoassay is based on the interaction of osmium-antigen conjugate with its antibody. The novelty presented herein is the direct conjugation of the osmium complex to a small antigen and the application of the quantitative analysis of the antigen and its antibody as the electrical signal for homogeneous immunoassay. The small antigen chosen is hippuric acid (HA), a major urinary metabolite in toluene-exposed humans. As a redox mediator, [Os(4,4'-dimethoxy-2,2'-bipyridine)2(4-aminomethylpyridine-HA)Cl](+/2+) (Os-HA antigen) has been synthesized and characterized on screen-printed carbon electrodes. The synthesized Os-HA antigen shows reversible redox peaks at E(½)=0.056 V versus Ag/AgCl. The homogeneous competitive immunoassay relies on the interaction between Os-HA antigen conjugate and free antigen to its antibody, which can generate electrical signals linearly proportional to the free antigen monitored by cyclic voltammetry and differential pulse voltammetry in the range of 10 µg mL(-1) to 5.12 mg mL(-1). The cutoff concentration of HA in urine samples is 2.0 mg mL(-1), so the method can be used to develop a HA immunosensor. Moreover, the proposed homogeneous electrochemical immunoassay method can be applied to detect low concentrations of small antigens found in the healthcare area.

Genome-Wide Pathway Exploration of the Epidermidibacterium keratini EPI-7T.

Functional cosmetics industries using skin microbiome screening and beneficial materials isolated from key microorganisms are receiving increasing attention. Since Epidermidibacterium keratini EPI-7T was first discovered in human skin, previous studies have confirmed that it can produce a new pyrimidine compound, 1,1'-biuracil, having anti-aging effects on human skin. Therefore, we conducted genomic analyses to judge the use value of E. keratini EPI-7T and provide up-to-date information. Whole-genome sequencing analysis of E. keratini EPI-7T was performed to generate new complete genome and annotation information. E. keratini EPI-7T genome was subjected to comparative genomic analysis with a group of closely-related strains and skin flora strains through bioinformatic analysis. Furthermore, based on annotation information, we explored metabolic pathways for valuable substances that can be used in functional cosmetics. In this study, the whole-genome sequencing (WGS) and annotation results of E. keratini EPI-7T were improved, and through comparative analysis, it was confirmed that the E. keratini EPI-7T has more metabolite-related genes than comparison strains. In addition, we annotated the vital genes for biosynthesis of 20 amino acids, orotic acid, riboflavin (B2) and chorismate. In particular, we were able to prospect that orotic acid could accumulate inside E. keratini EPI-7T under uracil-enriched conditions. Therefore, through a genomics approach, this study aims to provide genetic information for the hidden potential of E. keratini EPI-7T and the strain development and biotechnology utilization to be conducted in further studies.

A Mediator-Free Multi-Ply Biofuel Cell Using an Interfacial Assembly between Hydrophilic Enzymes and Hydrophobic Conductive Oxide Nanoparticles with Pointed Apexes.

Biofuel cells (BFCs) based on enzymatic electrodes hold great promise as power sources for biomedical devices. However, their practical use is hindered by low electron transfer efficiency and poor operational stability of enzymatic electrodes. Here, a novel mediator-free multi-ply BFC that overcomes these limitations and exhibits both substantially high-power output and long-term operational stability is presented. The approach involves the utilization of interfacial interaction-induced assembly between hydrophilic glucose oxidase (GOx) and hydrophobic conductive indium tin oxide nanoparticles (ITO NPs) with distinctive shapes, along with a multi-ply electrode system. For the preparation of the anode, GOx and oleylamine-stabilized ITO NPs with bipod/tripod type are covalently assembled onto the host fiber electrode composed of multi-walled carbon nanotubes and gold (Au) NPs. Remarkably, despite the contrasting hydrophilic and hydrophobic properties, this interfacial assembly approach allows for the formation of nanoblended GOx/ITO NP film, enabling efficient electron transfer within the anode. Additionally, the cathode is prepared by sputtering Pt onto the host electrode. Furthermore, the multi-ply fiber electrode system exhibits unprecedented high-power output (≈10.4 mW cm-2 ) and excellent operational stability (2.1 mW cm-2 , ≈49% after 60 days of continuous operation). The approach can provide a basis for the development of high-performance BFCs.

Rapid identification of SARS-CoV-2 in the point-of-care using digital PCR-based Dr. PCR™ Di20K COVID-19 Detection Kit without viral RNA extraction.

BACKGROUND: Since COVID-19 was declared the pandemic by the WHO, it has continued to spread. There is a need for rapid, efficient, and accurate diagnostic kits and techniques to control its spread. OBJECTIVE: The diagnostic capability of the qRT-PCR-based Real-Q 2019-nCoV Detection Kit and dPCR-based Dr. PCR™ Di20K COVID-19 Detection Kit was compared and evaluated. METHODS: Diagnostic tests for COVID-19 were performed using two different COVID-19 kits and 301 individual specimens with confirmed COVID-19 positive/negative at the government-accredited medical institution. Assessment of diagnostic capability was measured through diagnostic sensitivity, specificity, Cohen's Kappa coefficient, and dilutional linearity tests. RESULTS: The COVID-19 diagnostic test results using two kits and 301 individual specimens perfectly matched the pre-diagnosis results of the medical institution. In addition, the measurement results of diagnostic sensitivity and specificity were "1", indicating high diagnostic capability. Cohen's Kappa coefficient value is "1", which means that the diagnosis concordance between the two kits is "Almost Perfect". As a result of dilutional linearity tests to evaluate their detection capability, both kits were measured with very high detection reliability. CONCLUSION: Here, we propose that the dPCR-based Dr. PCR™ Di20K COVID-19 Detection Kit has the advantages of the dPCR method reported in the previous study and is suitable for point-of-care testing (POCT) by overcoming the limitations of space, test time, cross-over contamination, and biosafety due to omitting RNA extraction process.

Development of a Glucose Sensor Based on Glucose Dehydrogenase Using Polydopamine-Functionalized Nanotubes.

The electrochemical-based detection of glucose is widely used for diagnostic purposes and is mediated by enzyme-mediated signal transduction mechanisms. For such applications, recent attention has focused on utilizing the oxygen-insensitive glucose dehydrogenase (GDH) enzyme in place of the glucose oxidase (GOx) enzyme, which is sensitive to oxygen levels. Currently used Ru-based redox mediators mainly work with GOx, while Ru(dmo-bpy)2Cl2 has been proposed as a promising mediator that works with GDH. However, there remains an outstanding need to improve Ru(dmo-bpy)2Cl2 attachment to electrode surfaces. Herein, we report the use of polydopamine-functionalized multi-walled carbon nanotubes (PDA-MWCNTs) to effectively attach Ru(dmo-bpy)2Cl2 and GDH onto screen-printed carbon electrodes (SPCEs) without requiring a cross-linker. PDA-MWCNTs were characterized by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and thermal gravimetric analysis (TGA), while the fabrication and optimization of Ru(dmo-bpy)2Cl2/PDA-MWCNT/SPCEs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The experimental results demonstrate a wide linear range of glucose-concentration-dependent responses and the multi-potential step (MPS) technique facilitated the selective detection of glucose in the presence of physiologically relevant interfering species, as well as in biological fluids (e.g., serum). The ease of device fabrication and high detection performance demonstrate a viable pathway to develop glucose sensors based on the GDH enzyme and Ru(dmo-bpy)2Cl2 redox mediator and the sensing strategy is potentially extendable to other bioanalytes as well.

Diagnostic evaluation of qRT-PCR-based kit and dPCR-based kit for COVID-19.

BACKGROUND: Coronavirus disease of 2019 (COVID-19) is well known as a fatal disease, first discovered at Wuhan in China, ranging from mild to death, such as shortness of breath and fever. Early diagnosis of COVID-19 is a crucial point in preventing global prevalence. OBJECTIVE: We aimed to evaluate the diagnostic competency and efficiency with the Allplex™ 2019-nCoV Assay kit and the Dr. PCR 20 K COVID-19 Detection kit, designed based on the qRT-PCR and dPCR technologies, respectively. METHODS: A total of 30 negative and 20 COVID-19 positive specimens were assigned to the diagnostic test by using different COVID-19 diagnosis kits. Diagnostic accuracy was measured by statistical testing with sensitivity, specificity, and co-efficiency calculations. RESULTS: Comparing both diagnostic kits, we confirmed that the diagnostic results of 30 negative and 20 positive cases were the same pre-diagnostic results. The diagnostic statistics test results were perfectly matched with value (1). Cohen's Kappa coefficient was demonstrated that the given kits in two different ways were "almost perfect" with value (1). In evaluating the detection capability, the dilutional linearity experiments substantiate that the Dr. PCR 20 K COVID-19 Detection kit could detect SARS-CoV-2 viral load at a concentration ten times lower than that of the Allplex™ 2019-nCoV Assay kit. CONCLUSIONS: In this study, we propose that the dPCR diagnosis using LOAA dPCR could be a powerful method for COVID-19 point-of-care tests requiring immediate diagnosis in a limited time and space through the advantages of relatively low sample concentration and small equipment size compared to conventional qRT-PCR.

Two-Ply Carbon Nanotube Fiber-Typed Enzymatic Biofuel Cell Implanted in Mice.

Implantable devices have emerged as a promising industry. It is inevitable that these devices will require a power source to operate in vivo. Thus, to power implantable medical devices, biofuel cells (BFCs) that generate electricity using glucose without an external power supply have been considered. Although implantable BFCs have been developed for application in vivo, they are limited by their bulky electrodes and low power density. In the present study, we attempted to apply to living mice an implantable enzymatic BFC (EBFC) that was previously reported to be a high-power EBFC comprising carbon nanotube yarn electrodes. To improve their mechanical properties and for convenient implantation, the electrodes were coated with Nafion and twisted into a micro-sized, two-ply, one-body system. When the two-ply EBFC system was implanted in the abdominal cavity of mice, it provided a high-power density of 0.3 mW/cm2. The two-ply EBFC system was injected through a needle using a syringe without surgery and the inflammatory response in vivo initially induced by the injection of the EBFC system was attenuated after 7 days, indicating the biocompatibility of the system in vivo.

Performance of a glucose-reactive enzyme-based biofuel cell system for biomedical applications.

A glucose-reactive enzyme-based biofuel cell system (EBFC) was recently introduced in the scientific community for biomedical applications, such as implantable artificial organs and biosensors for drug delivery. Upon direct contact with tissues or organs, an implanted EBFC can exert effects that damage or stimulate intact tissue due to its byproducts or generated electrical cues, which have not been investigated in detail. Here, we perform a fundamental cell culture study using a glucose dehydrogenase (GDH) as an anode enzyme and bilirubin oxidase (BOD) as a cathode enzyme. The fabricated EBFC had power densities of 15.26 to 38.33 nW/cm2 depending on the enzyme concentration in media supplemented with 25 mM glucose. Despite the low power density, the GDH-based EBFC showed increases in cell viability (~150%) and cell migration (~90%) with a relatively low inflammatory response. However, glucose oxidase (GOD), which has been used as an EBFC anode enzyme, revealed extreme cytotoxicity (~10%) due to the lethal concentration of H2O2 byproducts (~1500 µM). Therefore, with its cytocompatibility and cell-stimulating effects, the GDH-based EBFC is considered a promising implantable tool for generating electricity for biomedical applications. Finally, the GDH-based EBFC can be used for introducing electricity during cell culture and the fabrication of organs on a chip and a power source for implantable devices such as biosensors, biopatches, and artificial organs.

Author Correction: Performance of a glucose-reactive enzyme-based biofuel cell system for biomedical applications.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Ultrasonic synthesis and characterization of poly(acrylamide)-co-poly(vinylimidazole)@MWCNTs composite for use as an electrochemical material.

Applying a nanocomposite to increase the conductivity of an electrode can facilitate electrochemical analysis. In this regard, multi-walled carbon nanotubes (MWCNTs) evenly dispersed in hydrophilic solution can play an important role in electrochemical bio-sensing due to their unique properties, such as their high electrical conductivity and ability to conjugate with hydrophilic enzymes. Herein, we report the simple ultrasonic synthesis of a highly dispersible, enzyme-binding nanocomposite, poly(acrylamide)-co-poly(vinyl imidazole) (7:1 mol ratio)-MWCNTs (PAA-PVI@MWCNTs). This material, having a zeta potential of 36.6 ±â€¯0.53 mV, was applied as a film to an electrode surface and stably bound with glucose oxidase to transfer an electron between the enzyme and electrode in the presence of glucose. The PAA-PVI@MWCNTs composite, which was readily dispersed in deionized water, can be used as a biocompatible material for applications such as bio-sensing, point-of-care testing (POCT), and other health care functions.

High-power biofuel cell textiles from woven biscrolled carbon nanotube yarns.

Biofuel cells that generate electricity from glucose in blood are promising for powering implantable biomedical devices. Immobilizing interconnected enzyme and redox mediator in a highly conducting, porous electrode maximizes their interaction with the electrolyte and minimizes diffusion distances for fuel and oxidant, thereby enhancing power density. Here we report that our separator-free carbon nanotube yarn biofuel cells provide an open-circuit voltage of 0.70 V, and a maximum areal power density of 2.18 mW cm(-2) that is three times higher than for previous carbon nanotube yarn biofuel cells. Biofuel cell operation in human serum provides high areal power output, as well as markedly increased lifetime (83% remained after 24 h), compared with previous unprotected biofuel cells. Our biscrolled yarn biofuel cells are woven into textiles having the mechanical robustness needed for implantation for glucose energy harvesting.

The adaptor protein LAD/TSAd mediates laminin-dependent T cell migration via association with the 67 kDa laminin binding protein.

The adaptor protein, LAD/TSAd, plays essential roles in T cell activation. To further understand the functions of this protein, we performed yeast two-hybrid screening using TSAd as bait and identified 67 kDa laminin binding protein (LBP) as the interacting partner. Subsequently, TSAd-LBP interaction was confirmed in D1.1 T cell line. Upon costimulation by T cell receptor (TCR) plus laminin crosslinking or TCR plus integrin alpha6 crosslinking, LBP was coimmunoprecipitated with TSAd. Moreover, TCR plus laminin costimulation-dependent T cell migration was enhanced in D1.1 T cells overexpressing TSAd but was disrupted in D1.1 cells overexpressing dominant negative form of TSAd or TSAd shRNA. These data show that, upon TCR plus integrin costimulation, TSAd associates with LBP and mediates T lymphocyte migration.