Electrochemical redox signaling of hemoglobin in human whole blood and its relevance to anemia and thalassemia diagnosis

A highly redox active human whole blood-carbon nanomaterial modified electrode has been developed, which showed a redox peak (vs. Ag/AgCl) similar to that of hemoglobin (vs. Ag/AgCl) in red blood cells. Clinical relevance of this for direct electrochemical analysis of blood hemoglobin content (anemia) and thalassemia disease diagnosis was demonstrated.

An electrochemical immunosensor for efficient detection of uropathogenic E. coli based on thionine dye immobilized chitosan/functionalized-MWCNT modified electrode

Uropathogenic Escherichia coli (UPEC) is the major cause of 150 million Urinary Tract Infections (UTI) reported annually world-wide. High prevalence of multi-drug-resistance makes it dangerous and difficult to cure. Therefore simple, quick and early diagnostic tools are essential for effective treatment and control. We report an electrochemical immunosensor based on thionine dye (Th) immobilized on functionalized-multiwalled carbon nanotube+chitosan composite coated on glassy carbon electrode (GCE/f-MWCNT-Chit@Th) for quick and sensitive detection of UPEC in aqueous solution. This immunosensor was constructed by sequential immobilization of UPEC, bovine serum albumin, primary antibody and Horse Radish Peroxidase (HRP) tagged secondary antibody on the surface of GCE/f-MWCNT-Chit@Th. When analyzed using 2.5mM of hydrogen peroxide reduction reaction using cyclic voltammetry in phosphate buffer, pH 7.0, the immunosensor showed excellent linearity in a range of 10(2)-10(9)cfu of UPEC mL(-1) with a current sensitivity of 7.162μA {log(cfumL(-1))}(-1). The specificity of this immunosensor was tested using other UTI and non-UTI bacteria, Staphylococcus, Klebsiella, Proteus and Shigella. The clinical applicability of the immunosensor was also successfully tested directly in UPEC spiked urine samples (simulated sample).

The Efficacy and Safety of Eberconazole Nitrate 1% and Mometasone Furoate 0.1% w/w Cream in Subjects with Inflamed Cutaneous Mycoses

BACKGROUND

Topical antifungal agents along with the steroids may provide not only rapid symptomatic relief but also clearance of disease causing fungi in inflamed cutaneous mycoses (ICM).

AIM

To assess the efficacy and safety of fixed dose combination (FDC) of Eberconazole nitrate 1% and Mometasone furoate 0.1% w/w cream, in subjects with ICM.

METHODS

This was a multi-centric, non-comparative study conducted in 155 eligible adult Indian subjects with ICM. They were treated with study medication for 21 days (D21) and followed up on day 35 (D35). Efficacy (by Investigator's Static Global Assessment-ISGA, symptom severity scores) and safety were assessed to evaluate the therapeutic response.

RESULTS

Of 155 subjects, 129 completed the study. Lesions healed completely in 77.52% and improved markedly in 22.48% patients by D21. There was a statistically significant reduction (p<0.001) in total symptom score (TSS) and mean severity scores of erythema, scaling and pruritus on days 7 and 21 compared to baseline. There was no treatment failure. Only 11 patients remained culture positive on D21 compared to 68 at baseline. Physicians evaluated the drug as 'Good' in 72% and 'Excellent' in 28% of subjects; adverse events were reported in 27.74% subjects and none was severe. There was a decrease in serum cortisol level in 4.52% (7/155) subjects and was considered clinically significant in three subjects. On D35, 18.55% and 24.20% subjects had greater ISGA score and TSS respectively, compared to D21.

CONCLUSION

Tested FDC demonstrated efficacy and was well tolerated by study population. It offers an effective and safe therapeutic option for the management of ICM.

In Situ Derivatization of an Intrinsic Iron Impurity as a Surface-Confined Iron(II)tris(2,2'-bipyridine) Complex on MWCNT and Its Application to Selective Electrochemical Sensing of DNA's Purine Bases

The derivatization of an intrinsic iron impurity in a carbon nanotube (CNT-*Fe, *Fe-intrinsic, and redox-active iron impurity) as a functional molecular system has been challenging to realize. There are certain limitations on the derivatization of such iron impurities such as low concentration and limited accessibility. Herein, we report an in situ electroassisted derivatization of an intrinsic and redox-active iron impurity in a multiwalled carbon nanotube (MWCNT-*Fe, *Fe, 2.1 wt %) as MWCNT-*Fe(bpy)3(2+), where Fe(bpy)3(2+) = iron(II)tris(2,2'-bipyridine) complex and bpy = 2,2'-bipyridine. The hybrid complex was prepared by the electrochemical treatment of a 2,2'-bipyridine ligand adsorbed {MWCNT-*Fe + Nafion} modified glassy carbon electrode in pH 7 phosphate buffer solution. This new MWCNT-*Fe(bpy)3(2+) hybrid electrode showed well-defined, stable redox at E1/2 = 830 mV with a peak-to-peak separation (ΔEp) of 72 mV in a neutral pH solution. This is quite different from an ex situ Nafion-Fe(bpy)3(2+) complex system that showed an unstable response at neutral pH. This in situ approach can allow the redox-active iron impurity in the CNTs to be quantified using the current signal of the Fe(bpy)3(2+) hybrid system. This MWCNT-*Fe(bpy)3(2+) hybrid modified electrode was further used as an electrochemical detector for selective and separation-less flow injection analysis of DNA's purine bases, adenine and guanine, without interference from pyrimidine bases, cytosine, and thymine at different oxidative detection potentials of 1 V (for adenine and guanine) and 0.7 V vs Ag/AgCl (for guanine) using the pH 7 phosphate buffer solution as a carrier system.

Electrochemical behavior of the 1,10-phenanthroline ligand on a multiwalled carbon nanotube surface and its relevant electrochemistry for selective recognition of copper ion and hydrogen peroxide sensing

1,10-Phenanthroline (Phen) is a well-known benchmark ligand and has often been used in the coordination chemistry for the complexation of transition metal ions, such as Fe(2+), Ni(2+), and Co(2+). Because the electro-oxidation potential of Phen is much higher (>2 V versus Ag/AgCl) than the water decomposition potential, i.e., ∼1.5 V versus Ag/AgCl, in pH 7, it is practically difficult to electro-oxidize Phen in aqueous medium using any conventional electrodes, such as glassy carbon electrode (GCE), gold, and platinum. Interestingly, herein, we report an unexpected oxidation of Phen to a highly redox active 1,10-phenanthroline-5,6-dione (Phen-dione) and its confinement on a multiwalled carbon nanotube (MWCNT)-modified glassy carbon electrode (GCE/MWCNT@Phen-dione) surface by potential cycling of Phen-adsorbed GCE/MWCNT (GCE/MWCNT@Phen) from -1 to 1 V versus Ag/AgCl in pH 7 phosphate buffer solution. GCE/MWCNT@Phen-dione showed selective recognition of copper ion (GCE/MWCNT@Phen-dione-Cu(2+)) by catalyzing the hydrogen peroxide reduction reaction in a neutral pH solution. The precise structure of the Phen electro-oxidized product has been identified after characterizing the electrode and/or ethanolic extract of the product by various techniques, such as Raman, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) (for copper complex), liquid chromatography-mass spectrometry (LC-MS), electrospray ionization-mass spectrometry (ESI-MS) (for copper complex), cyclic voltammetry (CV), and in situ electrochemical quartz crystal microbalance (EQCM) and comparing electrochemical behavior of several control compounds, such as phenanthrene and 9,10-phenanthrenequinone. It is concluded that the product formed is 1,10-phenanthroline-5,6-dione, wherein the dione position is ortho to each other and the copper ion is complexed with nitrogen of the phenanthroline ring. With extended electrochemical oxidation of a structurally similar ligand, 2,2'-bipyridine failed to show any such electrochemical dynamics. Finally, applicability of GCE/MWCNT@Phen-dione-Cu(2+) for electrochemical sensing of hydrogen peroxide in a couple of real samples is successfully demonstrated.

Simple electro-assisted immobilization of ciprofloxacin on carbon nanotube modified electrodes: its selective hydrogen peroxide electrocatalysis

Ciprofloxacin (Cf) is a synthetic fourth generation fluoroquinolone class antibiotic used for the treatment of gram-positive, gram-negative and mycobacterium species infections. Electrochemical characteristic of the Cf antibiotic on carbon nanotube modified glassy carbon electrode (GCE/CNT) in pH 7 phosphate buffer solution has been investigated. Electrochemically oxidized radical byproduct of the Cf drug, which is formed as intermediate, gets immobilized on the GCE/CNT (GCE/Cf@CNT) and showed stable and well defined surface confined redox peak at -0.220 V versus Ag/AgCl. Control electrochemical experiment with unmodified GCE failed to show any such immobilization and redox features. Physicochemical characterizations of the Cf@CNT by transmission electron microscope, scanning electron microscope, infrared spectroscopy, UV-Vis and gas chromatography coupled mass spectroscopic analyses of Cf@CNT collectively revealed presence of native form of the Cf antibiotic molecule onto the CNT. The interaction between the Cf molecule and the CNT tubes are revealed from the decreased intensity in the Raman spectrum. The GCE/Cf@CNT showed excellent electrocatalytic response to hydrogen peroxide reduction reaction in pH 7 phosphate buffer solution. Amperometric i-t analysis for the detection of H2O2 showed a current linearity plot upto [H2O2] = 200 μM at an applied potential - 0.1 V versus Ag/AgCl with a current sensitivity value 678 μA mM(-1) cm(-2). No interferences were noticed with ascorbic acid, uric acid, cysteine and nitrite. The present study can be highly helpful to understand the interaction between the Cf and H2O2 in physiological systems and for the removal of Cf from the antibiotic polluted water samples especially in the aquaculture and agricultural systems.

Renal denervation therapy for resistant hypertension: a clinical update

Severe hypertension (systolic blood pressure (BP) ⩾160 mm Hg) resistant to treatment with multiple antihypertensive medications, poses a serious challenge to therapeutic treatment. Catheter-based renal denervation (RDN) is being increasingly proposed and researched as a safe and effective method of treating this condition. This article evaluates the existing evidence on the effects of RDN on BP reduction and other conditions with increased sympathetic tone. Findings indicate that RDN is a safe and effective treatment for severe hypertension. Moreover, the antihypertensive response to RDN is sustained for up to 3 years of follow-up. RDN decreases office BP more than ambulatory BP, which may be explained by the white-coat effect that causes an increase in office BP. Findings indicate that although reinnervation may occur following RDN, it does not appear to attenuate or reverse the BP response over 24-36 months. There is also evidence that patients with milder forms of hypertension may benefit from RDN. Furthermore, there is emerging evidence that RDN may have a role in the treatment of heart failure, obstructive sleep apnea, insulin resistance, atrial fibrillation and hypertension associated with end-stage renal disease. Taking into account that resistant hypertension and other diseases associated with elevated sympathetic tone are associated with significant morbidity and mortality rates, RDN therapy may be expected to have a significant impact on public health.

Electrochemical conversion of unreactive pyrene to highly redox-active 1,2-quinone derivatives on a carbon nanotube-modified gold electrode surface and its selective hydrogen peroxide sensing

Pyrene (PYR) is a rigid, carcinogenic, unreactive, and nonelectrooxidizable compound. A multiwalled carbon nanotube (MWCNT)-modified gold electrode surface-bound electrochemical oxidation of PYR to a highly redox-active surface-confined quinone derivative (PYRO) at an applied potential of 1 V versus Ag/AgCl in pH 7 phosphate buffer solution has been demonstrated in this work. Among various carbon nanomaterials examined, the pristine MWCNT-modified gold electrode showed effective electrochemical oxidation of the PYR. The MWCNT's graphite impurity promotes the electrochemical oxidation reaction. Physicochemical and electrochemical characterizations of MWCNT@PYRO by Raman spectroscopy, FT-IR, X-ray photoelectron spectroscopy, and GC-MS reveal the presence of PYRO as pyrene-tetrone within the modified electrode. The quinone position of PYRO was identified as ortho-directing by an elegantly designed ortho-isomer-selective complexation reaction with copper ion as an MWCNT@PYRO-Cu(2+/1+)-modified electrode. Finally, a cytochrome c enzyme-modified Au/MWCNT@PYRO (i.e., Au/MWCNT@PYRO-Cyt c) was also developed and further demonstrated for the selective biosensing of hydrogen peroxide.

Selective electrochemical recognition of the α-naphthol isomer and in situ immobilization of naphthoquinones for tunable electrocatalysis

Fits like a glove: Separationless and selective electrochemical oxidation of the α-naphthol (α-NAP) isomer yields naphthoquinone species on the surface of multiwalled carbon nanotubes, which can further catalyze the electro-oxidation of NADH and hydrazine at different potentials. The β-NAP isomer failed to show any such electro-oxidation.

Flow injection analysis of zinc pyrithione in hair care products on a cobalt phthalocyanine modified screen-printed carbon electrode

Zinc pyrithione (ZPT) is an antibacterial and antifungal reagent that is often utilized for the antidandruff activity in hair-care shampoos with a composition level up to 1% in the formulation. It has some adverse effects to human and animal if consumed orally. A disposable type of cobalt phthalocyanide modified screen-printed carbon electrode (CoPc/SPE) in couple with flow injection analysis (FIA) was developed for easy and selective analysis of ZPT in commercial hair-care products. Under the optimized FIA conditions, the CoPc/SPE yielded a linear calibration plot in the window of 6-576muM with sensitivity and detection limit of 1.65nAmuM(-1) and 0.9muM (i.e. 1.42pg in 5mul sample loop), respectively, in 0.1M KOH solution at an applied potential of 0.3V versus Ag/AgCl. Since the approach is simple, easy, selective, and inexpensive, it offers a potential application of daily ZPT analysis in hair-care products.

Transanal endoscopic microsurgery for rectal carcinoids: the largest reported United States experience

AIM

Rectal carcinoids are often inadequately resected by snare excision during colonoscopy. Transanal endoscopic microsurgery is a minimally invasive procedure with low morbidity that offers full-thickness excision with a low rate of negative margins. It presents an excellent alternative to radical surgery for mid and proximally located lesions. We report the largest United States (US) experience in the use of transanal endoscopic microsurgery for rectal carcinoids.

METHOD

Data of patients who had undergone transanal endoscopic microsurgery for rectal carcinoids were prospectively collected and retrospectively analyzed. Patient and tumour characteristics, operative and perioperative details, as well as oncological outcomes were reviewed.

RESULTS

Over a 12-year period, 24 patients underwent transanal endoscopic microsurgery for rectal carcinoids. Of these, six (25%) were primary surgical resections and 18 (75%) were performed after incomplete snare excisions during colonoscopy. Three (17%) patients who underwent full-thickness resection after snare excision had residual tumour on histopathological examination. Negative margins were obtained in all cases. No recurrences were noted.

CONCLUSION

Transanal endoscopic microsurgery is effective and safe for the surgical resection of rectal carcinoids<2 cm in diameter, with typical features and located more than 5 cm from the anal verge. Transanal endoscopic microsurgery can be used for primary resection or for resection after incomplete colonoscopic snare excision.

Room temperature aerobic oxidation of amines by a nanocrystalline ruthenium oxide pyrochlore nafion composite catalyst

The aerobic oxidation of primary amines to their respective nitriles has been carried out at room temperature using a highly reusable nanocrystalline ruthenium oxide pyrochlore Nafion composite catalyst (see figure).