A green cellulose nanofiber-based printed electrode for practical highly sensitive amoxicillin detection.

Simple electrochemical detection of the antibiotic amoxicillin (AMX) in water is crucial to mitigate health and environmental risks; however, the process requires single-use electrodes, which can increase the waste generated as well as the cost. Cellulose nanofibers (CNFs) are biodegradable materials that can be used as electrode frameworks. In this study, a sensitive single-use CNF-based printed electrode modified with polybenzimidazole (PBI)-wrapped multi-walled carbon nanotubes (MWCNTs) is developed for AMX detection. The CNF-based printed electrode achieved a detection limit of 0.3 µM and exhibited a wider detection range of 0.3-500 µM compared with electrodes developed in previous studies. In addition, the electrode reactions of AMX were electrochemically investigated and found to primarily involve the adsorbed species at low AMX concentrations and be diffusion-controlled at high AMX concentrations. Finally, the printed electrodes were used for the easy and practical determination of AMX in seawater and tap water by a soaking method. Satisfactory results were obtained, and the final concentrations of AMX were determined using simple calibration equations. Therefore, this CNF-based electrode exhibits great potential for practical real-time AMX detection in the field.

Electrochemical sensing of dual biomolecules in live cells and whole blood samples: A flexible gold wire-modified copper-organic framework-based hybrid composite.

For clinical research, the precise measurement of hydrogen peroxide (H2O2) and glucose (Glu) is of paramount importance, due to their imbalanced concentrations in blood glucose, and reactive oxygen species (ROS) play a huge role in COVID-19 viral disease. It is critical to construct and develop a simple, rapid, flexible, long-term, and sensitive detection of H2O2 and glucose. In this paper, we have developed a unique morphological structure of MOF(Cu) on a single-walled carbon nanotube-modified gold wire (swnt@gw). Highly designed frameworks with nanotube composites enhance electron rate-transfer behavior while extending conductance and electroactive surface area.The composite sensing system delivers wide linear-range concentrations, low detection limit, and interference-free performance in co-existence with other biomolecules and metal ions. Endogenous quantitative tracking of H2O2 was performed in macrophage live-cells with the help of a strong stimulator lipopolysaccharide.The composite device was effectively utilized for the measurement of H2O2 and glucose in turbid samples of whole blood and milk samples without a pretreatment process. The practical results of biofluids showed favorable voltammetric results and acceptance recovery percentage levels between 97.49 and 98.88%. Finally, a flexible MOF-based hybrid system may provide a suitable detection platform in the construction of electro-biosensors and hold potential promise for clinical-sensory applications.

Progress and current trends in the electrochemical determination of phosphate ions for environmental and biological monitoring applications.

The determination of phosphate ions in biological testing is critical for environmental safety. A reliable and accurate method is required to measure the true phosphate ion concentrations; in this regard, the electrochemical method is preferable because of its simple operation, fast response, and high sensitivity. By compiling existing electroanalytical techniques, researchers can compare the advantages and disadvantages of each method. This review examines the progress and recent advances in electrochemical sensing strategies adapted for the determination of phosphate ions in the environmental and during biological monitoring. We first discuss the history of phosphorus and the development of methods to detect phosphates. The recognition elements of phosphate ion sensors for environmental applications include metal-based, nanomaterial-based, carbon-based, and enzymatic electrodes. Phosphate determination in biological samples, such as blood serum, drugs, and other biological fluids, such as urine and saliva, as well as phosphate esters, is also discussed. The final part of our review addresses the current challenges that phosphate sensing technology faces and illustrates future opportunities for more reliable phosphate detection.

Fluorescence spectrophotometry for COVID-19 determination in clinical swab samples.

Considering the limitations of the assays currently available for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its emerging variants, a simple and rapid method using fluorescence spectrophotometry was developed to detect coronavirus disease 2019 (COVID-19). Forty clinical swab samples were collected from the nasopharyngeal and oropharyngeal cavities of COVID-19-positive and -negative. Each sample was divided into two parts. The first part of the samples was analyzed using reverse transcription-polymerase chain reaction (RT-qPCR) as the control method to identify COVID-19-positive and -negative samples. The second part of the samples was analyzed using fluorescence spectrophotometry. Fluorescence measurements were performed at excitation and emission wavelengths ranging from 200 to 800 nm. Twenty COVID-19-positive samples and twenty COVID-19-negative samples were detected based on RT-qPCR results. The fluorescence spectrum data indicated that the COVID-19-positive and -negative samples had significantly different characteristics. All positive samples could be distinguished from negative samples by fluorescence spectrophotometry. Principal component analysis showed that COVID-19-positive samples were clustered separately from COVID-19-negative samples. The specificity and accuracy of this experiment reached 100%. Limit of detection (LOD) obtained 42.20 copies/ml (Ct value of 33.65 cycles) for E gene and 63.60 copies/ml (Ct value of 31.36 cycles) for ORF1ab gene. This identification process only required 4 min. Thus, this technique offers an efficient and accurate method to identify an individual with active SARS-CoV-2 infection and can be easily adapted for the early investigation of COVID-19, in general.

Phase I clinical study of NMB58, a novel positron emission tomography (PET)-myocardial perfusion imaging tracer, conducted to evaluate its safety and pharmacokinetics in Japanese healthy adult males.

OBJECTIVES: NMB58 is a novel positron emission tomography (PET) tracer containing flurpiridaz as an active ingredient and available as a myocardial perfusion imaging tracer that targets mitochondrial complex 1. A phase I clinical study of NMB58 was conducted to evaluate its safety and pharmacokinetics in healthy volunteers. METHODS: Ten healthy Japanese volunteers received bolus injection of NMB58 (111-167 MBq) intravenously and underwent imaging studies at rest on day 1. Of these subjects, 5 (day 2 cohort 1; exercise stress) and 5 (day 2 cohort 2; pharmacological stress) similarly underwent stress imaging studies on day 2. The safety of NMB58 was evaluated through monitoring of signs/symptoms, electrocardiography, vital signs, and laboratory examinations at baseline and several time points during 3 days. Sequential whole-body positron emission tomography-computed tomography (PET/CT) scan data were acquired for up to 5-h post-injection, with venous blood and urine samples collected for up to 8-h post-injection. Based on the results of the biodistribution study, the absorbed radiation dose (Rad) was estimated by the Medical Internal Radiation Dose method. RESULTS: On day 1, the kidneys were shown to have the highest Rad, followed by the myocardium. On day 2, the myocardium was shown to have the highest Rad, followed by the kidneys. The mean effective doses (EDs) per unit activity administered were 0.021, 0.017 and 0.021 mSv/MBq for overall subjects (day 1), day 2 cohort 1 and day 2 cohort 2, respectively. The estimated exposure dose of NMB58 was similar to or lower than those of radiotracers currently approved for clinical use, including 18F-Fludeoxyglucose. Biodistribution results indicated that NMB58 distributed to the myocardium exhibited high and sustained retention after administration. The cumulative urinary radioactivity excretion rate was shown to be 6.9, 2.3%, and 8.0% of the injected dose in overall subjects (day 1), day 2 cohort 1 and day 2 cohort 2. There were no drug-related adverse events, and the tracer was well tolerated in all subjects. CONCLUSIONS: Based on radiation dosimetry, biodistribution, and safety evaluations, NMB58 was found to be a suitable tracer for clinical use in PET myocardial perfusion imaging during exercise or pharmacological stress.

Cellulose nanofiber-based electrode as a component of an enzyme-catalyzed biofuel cell.

Many types of flexible, wearable, and disposable electronic devices have been developed as chemical and physical sensors, and many solar cells contain plastics. However, because of environmental pollution caused by microplastics, plastic use is being reduced worldwide. We have developed an enzyme-catalyzed biofuel cell utilizing cellulose nanofiber (CNF) as an electrode component. The electrode was made conductive by mixing multi-walled carbon nanotubes with the CNF. This prepared biofuel cell was wearable, flexible, hygroscopic, biodegradable, eco-friendly, and readily disposable like paper. The CNF-based enzyme-catalyzed biofuel cell contained a flavin adenine dinucleotide-dependent glucose dehydrogenase bioanode and laccase biocathode. The maximum voltage and maximum current density of the biofuel cell were 434 mV and 176 µA cm-2, respectively, at room temperature (15-18 °C). The maximum power output was 27 µW cm-2, which was converted to 483 (±13) µW cm-3.

Hydrothermal preparation of a platinum-loaded sulphated nanozirconia catalyst for the effective conversion of waste low density polyethylene into gasoline-range hydrocarbons.

A platinum-loaded sulphated nanozirconia (Pt/nano ZrO2-SO4) bifunctional metal-acid catalyst was synthesized using a hydrothermal process. The nano ZrO2-SO4 was initially prepared by dispersing the nano ZrO2 in H2SO4, followed by wet impregnation via heating in an aqueous PtCl4 solution. This material was subsequently calcined and reduced under hydrogen gas to produce the catalyst. The Pt/nano ZrO2-SO4 was found to be a highly active, selective and stable solid acid catalyst for the conversion of waste low density polyethylene (LDPE) to high value hydrocarbons. The catalytic activity and stability of this material were evaluated during the hydrocracking of waste LDPE while optimizing the reaction temperature, time and catalyst-to-feed ratio. The activity of catalyst prepared by hydrothermal was attributed to highly dispersion of Pt species interacting with the support and inhibition of the agglomeration process. The impregnation method of hydrothermal generated highly active and selective catalyst with Pt loads of 1 wt%. The hydrocracking of waste LDPE over Pt/nanoZrO2-SO4 at 250 °C for 60 min with a catalyst-to-feed proportion of 1 wt% gave the largest gasoline fraction.

Phase IIa clinical study of [18F]fluciclovine: efficacy and safety of a new PET tracer for brain tumors.

OBJECTIVE: [18F]Fluciclovine (anti-[18F]FACBC) has demonstrated diagnostic efficacy for cancers of the brain where [18F]fludeoxyglucose has limitations. We conducted a phase IIa study of anti-[18F]FACBC to assess its accumulation pattern and safety in patients with malignant glioma. METHODS: Five patients with glioma scheduled for brain tumor resection received anti-[18F]FACBC. Brain positron emission tomography (PET) was performed following intravenous administration of anti-[18F]FACBC, and subsequently, preoperative gadolinium contrast-enhanced T1-weighted (CE-T1W) magnetic resonance imaging (MRI) was performed for surgery. Specimens for histopathological evaluation were collected during surgery, and their location was precisely determined on CE-T1W MRI and anti-[18F]FACBC PET/CT images. In addition, tumor extent defined on the MRI and PET/CT images was compared. To determine time-activity curves for anti-[18F]FACBC uptake in brain tumor and normal tissues, regions of interest were set in the brain tumor, contralateral normal tissue and the cerebellum, and their standardized uptake values (SUV) were calculated. The safety of anti-[18F]FACBC was assessed based on subjective symptoms and objective findings, electrocardiograms, vital signs, laboratory results, and the incidence of adverse events. RESULTS: Anti-[18F]FACBC accumulated in the malignant gliomas of all patients. CE-T1W MRI detected gliomas in all patients, but anti-[18F]FACBC PET/CT generally delineated wider regions of tumor extent than CE-T1W MRI. Two of the histopathologically confirmed tumors were located in regions that were defined using anti-[18F]FACBC PET/CT, but not using CE-T1W MRI. Two patients experienced three mild adverse events: one complained of a dull headache and later a mild headache, and the other showed general malaise. These symptoms resolved spontaneously without treatment. Only the mild headache could not be ruled out from having a causal relationship with anti-[18F]FACBC. Favorable T/N ratios regarding anti-[18F]FACBC uptake between tumors and normal control tissues were demonstrated in this trial. CONCLUSIONS: It is suggested that anti-[18F]FACBC PET/CT has the ability to delineate glioma spread that is undetectable using CE-T1W MRI. Anti-[18F]FACBC is safe in patients with malignant glioma. This study was registered in the Japan Pharmaceutical Information Center Clinical Trials Information, which is one of the World Health Organization registries (registration number: JapicCTI-111387).

Expression and localization of epidermal growth factor, transforming growth factor-α and epidermal growth factor receptor in the canine testis.

Gene expression of epidermal growth factor (EGF), transforming growth factor-α (TGF-α) and EGF receptor (EGF-R) and the localization of the corresponding proteins in the canine testis were studied. Levels of mRNA expressions were determined by semiquantitative reverse transcription polymerase chain reaction in the testes of the peripubertal (4-6 months), young adult (3-4 years), advanced adult (7-8 years) and senescent (11-16 years) groups. The EGF-R mRNA level in the testes of the peripubertal group was significantly higher than those in the other groups, whereas there was no difference in EGF and TGF-α mRNA levels among groups. Immunohistochemical stainings for EGF, TGF-α and EGF-R in the testis revealed that immunoreactivity in the seminiferous epithelium and Sertoli cell was weak and nonspecific for the stage of spermatogenesis, and distinct staining was found in Leydig cells. These results suggest that the EGF family of growth factors may be involved in testicular maturation and function in the dog.

Laccase bioelectrocatalyst at a steroid-type biosurfactant-modified carbon nanotube interface.

Achieving oxygen reduction at high positive potentials with fast heterogeneous electron transfer is desirable for the biocathode of fuel cells based on enzymes. Here, we present an effective interface for obtaining direct electron transfer from a laccase (Lac)-based cathode for O2 reduction, starting from a potential very close to the redox equilibrium potential of the oxygen/water couple. The interface between Lac and single-walled carbon nanotubes was improved by modification with the steroid biosurfactant sodium cholate. The heterogeneous electron-transfer rate between the type-1 Cu site of Lac and the modified electrode was determined to be 3000 s(-1). The electron-transfer rate was sensitive to the side chain of the steroid biosurfactant, and the rate decreased more than 10-fold when sodium deoxycholate was used as the side chain.

Self-assembly of a family of suprametallomacrocycles: revisiting an o-carborane bisterpyridyl building block.

The self-assembly of the o-carborane-based, bisterpyridyl monomer, 1,2-bis[4'-(4-ethynylphenyl)-2,2':6',2''-terpyridine]-o-carborane, utilizing either Zn(II) or Fe(II) in a precise metal : ligand ratio (1 : 1), generated a family of metallomacrocycles that were studied via ESI-TWIM-MS, (1)H NMR, and 2D NMR (COSY, NOESY). Under kinetic control, via formation of Fe(II) complexes, the main cyclic product was triangular, as is typical of 60°-based bisligands. Under thermodynamic control using more labile transition metal complexes, e.g. Zn(II), the ratio of cyclic species was found to be concentration and temperature dependent, and under an adequate entropic driving force, the cyclic dimer was formed. This system was probed via variable temperature NMR to reveal dynamic equilibrium between the entropically favored dimer and enthalpically favored trimer.

Effect of N-doping of single-walled carbon nanotubes on bioelectrocatalysis of laccase.

Nondoped and N-doped SWCNTs (N-SWCNTs) were used to clarify the effect of N-doping on a direct electron transfer (DET) reaction of laccase (Lac, from Trametes sp.). The level of N-doping in the carbon phase of the N-SWCNTs, which were synthesized by a CVD method, was determined to be 0.1, 2.4, and 4.1% from X-ray photoelectron spectroscopy measurements. The N-SWCNTs were also carefully characterized using electron microscopy, Brunauer-Emmett-Teller (BET) specific surface area measurements, Raman spectroscopy, and electrochemistry. The bioelectrocatalytic current for the DET reaction of Lac immobilized onto the N-SWCNTs tended to decrease with increasing N dopant ratio, whereas the amount of Lac adsorbed per BET surface area of the N-SWCNTs did not depend on the N dopant ratio. There were two main explanations for this behavior. First, an electrostatic interaction between the positively charged interface of the N-SWCNTs due to nitrogen species surface functional groups and the negative charges of carboxylate residues surrounding the T1 site. Second, the surface potential of the N-SWCNTs during Lac modification, because the slope value of the surface potential versus N dopant ratio of the N-SWCNTs was about 53 mV/N%. From additional investigations into the surface potential effect and thermodynamic investigations, we carefully concluded that the above behaviors may be due to denaturation and/or decreasing of the DET reaction rate caused by the strong electrostatic interaction between Lac and the N-SWCNTs surface.

o-Carborane-based biphenyl and p-terphenyl derivatives.

The synthesis and properties of biphenyl- and p-terphenyl-fused o-carboranes are described. Aryl rings in the biphenyl and p-terphenyl skeletons are highly coplanar because of the presence of the o-carborane unit. o-Carborane exhibits an electron-withdrawing character via the inductive effect, resulting in a decrease in both the HOMO and LUMO levels of oligophenyls without causing electronic perturbation.

Determination of the diameter-dependent onset potential for the oxygenation of SWCNTs.

The evaluation of the diameter-dependent onset potential for the oxygenation of a SWCNT (single-walled carbon nanotube) is an important issue because its chemical and physical properties, such as chemical reactivity, electronic conductance, and optical characteristics, would be changed. We investigated the diameter-dependent onset potential for the oxygenation of SWCNTs in neutral aqueous solution by using in situ Raman spectroelectrochemical measurements, which was explained quantitatively in terms of the strain energy per carbon atom. These results will be useful for the fabrication of materials in which CNTs are used as a platform for applications such as fuel cells, capacitors, and Li-ion batteries.

Luminescent polymer consisting of 9,12-linked o-carborane.

The synthesis of novel luminescent polymer containing p-phenylene-ethynylene and 9,12-linked o-carborane units alternately in the main chain is reported. The obtained polymer exhibits intense blue photoluminescence, providing the first insights into the optical properties of a 9,12-disubstituted o-carborane dye. π-Conjugated substituent at 9 and/or 12-positions in o-carborane is electrically independent, and both the HOMO and the LUMO levels slightly increase, whereas LUMO of the π-conjugated substituent at 1 and/or 2-positions in o-carborane decrease. Thus, it is deduced that polymers consisting of the 9,12-linked o-carborane unit are able to be applied as light-emitting materials.

Synthesis and properties of thiophene-fused benzocarborane.

The o-carborane-based π-conjugated compound, benzocarborano- [2,1-b:3,4-b']dithiophene was synthesized. Its crystal structure revealed high coplanarity for the two thiophene rings of the 2,2'-bithiophene skeleton, which is fixed in the cisoid structure by the o-carborane unit. Theoretical calculations indicated non-aromaticity for its center C(6) ring moiety as well as decreased HOMO and LUMO levels. The o-carborane moiety provides an electron-withdrawing character to the 2,2'-bithiophene unit through an inductive effect.

Sensitivity to electrical stimulation of human immunodeficiency virus type 1 and MAGIC-5 cells.

To determine the sensitivities to low electrical potential of human immunodeficiency virus type 1 (HIV-1) and its target cells, HIV-1 and MAGIC-5 cells were directly stimulated with a constant direct current potential of 1.0 V (vs. Ag/AgCl). HIV-1 was incubated for 3 h at 37°C on a poly-L-lysine-coated indium-tin oxide electrode, and then stimulated by an electrical potential. MAGIC-5 cells were seeded onto the electrically stimulated HIV-1 and cultured for 3 days at 37°C. HIV-1-infected cells were measured by multinuclear activation via a galactosidase indicator assay. MAGIC-5 cells were also stimulated by an electrical potential of 1.0 V; cell damage, proliferation and apoptosis were evaluated by trypan blue staining, cell counting and in situ apoptosis detection, respectively. HIV-1 was found to be damaged to a greater extent by electrical stimulation than the cells. In particular, after application of a 1.0-V potential for 3 min, HIV-1LAI and HIV-1KMT infection were inhibited by about 90%, but changes in cell damage, proliferation and apoptosis were virtually undetectable. These results suggested that HIV-1 is significantly more susceptible to low electrical potential than cells. This finding could form the basis of a novel therapeutic strategy against HIV-1 infection.

Aromatic Ring-Fused Carborane-Based Luminescent π-Conjugated Polymers.

A series of π-conjugated polymers linked by benzocarborane (1,2-(buta-1',3'-diene-1',4'-diyl)-1,2-dicarbadodecaborane) were synthesized via Sonogashira-Hagihara polycondensation reaction. The opened molecular structure of diiodo monomer containing benzocarborane resulted in fast polymerization and high molecular weights. The obtained polymers were fully characterized by (1) H, (13) C, and (11) B NMR spectroscopies. UV-vis absorption and photoluminescence studies revealed the acceptor-profile of benzocarborane. Unlike the polymers linked by o-carborane, these polymers exhibited strong luminescence in the solution state, presumably because the inductive effect of carborane is dominant, rather than cage-π interactions.

D-fructose detection based on the direct heterogeneous electron transfer reaction of fructose dehydrogenase adsorbed onto multi-walled carbon nanotubes synthesized on platinum electrode.

Multi-walled carbon nanotubes (MWCNTs) were synthesized on platinum plate electrodes by the chemical vapor deposition (CVD) method. From the results of X-ray photoelectron spectroscopy and voltammetric investigation, the iron nanoparticles used as a catalyst for the MWCNT synthesis were enclosed with MWCNTs. The MWCNTs synthesized on the Pt plate (MWCNTs/Pt) electrode were immediately immersed into solutions of d-fructose dehydrogenase (FDH) to immobilize the enzyme onto the MWCNTs/Pt electrode surfaces. After the FDH was immobilized onto the MWCNTs/Pt electrode, a well-defined catalytic oxidation current based on FDH was observed from ca. -0.15V (versus Ag/AgCl/sat'd KCl), which was close to the redox potential of heme c as a prosthetic group of FDH. From an analysis of a plot of the catalytic current versus substrate, the calibration range for the fructose concentration was up to ca. 40mmoldm(-3), and the apparent Michaelis-Menten constant was evaluated to be 11+/-1mmoldm(-3).

Gold single-crystal electrode surface modified with self-assembled monolayers for electron tunneling with bilirubin oxidase.

Using Au(111) and Au(100) single-crystal electrodes modified with self-assembled monolayers (SAMs), the direct electron transfer reaction of bilirubin oxidase (BOD) adsorbed onto their surfaces was investigated. The BOD adsorbed onto the Au(111), Au(100) and gold /mica electrodes, and the BOD adsorbed onto Au(111) electrodes modified with C(3)-SO(3)H and C(n)-COOH (n = 2, 5 and 7), showed the electrocatalytic currents of dioxygen reduction based on the direct electron transfer reaction. The BOD adsorbed onto Au(111) electrodes modified with C(6)-NH(2), C(6)-OH and C(5)-CH(3) did not show any electrocatalytic current. Negatively charged electrode surfaces can give a suitable molecular orientation for the direct electron transfer of BOD. The k degrees values evaluated by an analysis of the steady-state voltammogram with a simulated fitting method did not depend on the crystal structure of the gold electrode surface. Using a C(n)-COOH (n = 2, 5, 7) modified Au(111) electrode, the k degrees values decreased with an increasing alkyl chain length of C(n)-COOH. Based on the k degrees values obtained from the C(n)-COOH (n = 2, 5, 7) modified Au(111) electrodes, the electron tunneling distance was evaluated. The average distance between the type 1 Cu site of BOD and the outside of the BOD protein structure was evaluated to be 17 (+/-2) A.