Aggregation and Stabilization of Colloidal Spheroids by Oppositely Charged Spherical Nanoparticles

Heteroaggregation of colloids is an important yet complex physical process involving colloidal/nanosized particles and is relevant in river delta formation, paper-making, water treatment, blood flocculation, and so on. Despite the earlier studies on oppositely charged spherical colloids, heteroaggregation of colloids of different shapes is less explored. In this regard, we report an experimental study to investigate the colloidal stability of mixture of positively charged spheroidal hematite and negatively charged spherical silica nanoparticles. In this study, pH and surface area ratio (silica to hematite, <i>S</i>_S–H) are varied to tune the colloidal stability/instability of the suspension. At pH 6.5 and low <i>S</i>_S–H, the silica particles adsorb onto the hematite particles and reduce the effective charge of the latter, leading to aggregation and resulting in unstable dispersions. At higher S_S–H, adsorption of silica on hematite leads to overcharging and charge reversal, which leads to a stable dispersion. Similar experiments were performed at pH 2.4 and 3.5, and the crossover from unstable to stable dispersion is observed as a function of <i>S</i>_S–H. Calculation of Derjaguin, Landau, Verwey, and Overbeek (DLVO) interaction between particles in the binary mixture, as a function of pH and <i>S</i>_S–H, based on the aggregate size and zeta potential, explains the transition from unstable to stable dispersion. The size and zeta potential of heteroaggregates in the dispersion were analyzed by dynamic light scattering (DLS) technique. Adsorption of silica nanoparticles on hematite particles was visualized by scanning electron microscopy (SEM). The study provides a framework based on DLVO interactions to stabilize or destabilize a colloidal dispersion of nonspherical particles by controlled addition of oppositely charged spherical colloids, which is a feat that is not possible with simple salt. The stability ratio (<i>W</i>) calculated from DLVO interactions demark the unstable–stable dispersion regions, which is found to be in agreement with the experimental results

Clinical profile and outcome of parathyroid adenoma-associated pancreatitis

Background: Primary hyperparathyroidism due to parathyroid adenoma presenting with pancreatitis as the initial manifestation is rare. The causal relationship between pancreatitis and primary hyperparathyroidism is debatable. Objective: To study the clinical and biochemical profile of patients with parathyroid adenoma-associated pancreatitis as well as the outcome following parathyroidectomy. Methods: The authors retrospectively studied the clinical and biochemical parameters of patients with acute, recurrent acute and chronic pancreatitis who underwent parathyroidectomy for parathyroid adenoma at Asian Institute of Gastroenterology, Hyderabad, India, between April 2010 and June 2016. Results: Of the total 3962 patients who presented with recurrent acute and chronic pancreatitis, 77 (1.94%) patients had parathyroid adenoma-associated pancreatitis and were included in this study for further analysis. Of these, 41 (53.2%) had recurrent acute pancreatitis and 36 (46.8%) had chronic pancreatitis. Serum calcium (12.4 ± 1.7 mg/dl) and parathyroid hormone levels (367 ± 286.4 pg/ml) were found to be elevated. Left inferior parathyroid adenoma (37.7%) was the most common finding on neck imaging. Patients with chronic pancreatitis had a longer disease duration (3.8 ± 5 years) and more pain episodes (10.7 ± 10.2) than those with recurrent acute pancreatitis (0.62 ± 0.7 years and 2.6 ± 2.7, respectively) (P = 0.0001). In all the patients, following parathyroidectomy, there was a significant decrease in serum calcium (12.4 ± 1.7 mg/dl vs. 9.7 ± 1.9 mg/dl; P = 0.0001) and serum parathyroid hormone levels (367 ± 286.4 pg/ml vs. 116.4 ± 47.1 pg/ml; P = 0.0001) as well as there was a reduction in the number of episodes and severity of pain. Conclusions: Estimating serum calcium after an episode of unexplained pancreatitis is important and can help minimize delay in diagnosing primary hyperparathyroidism, and possibly prevent the progression of pancreatitis. Parathyroidectomy improves the clinical outcome of primary hyperparathyroidism and prevents further attacks of pancreatitis

Superior grafting and state-of-the-art interfacial electron transfer rates for newly designed geminal dicarboxylate bound ruthenium(II)– and osmium(II)–polypyridyl dyes on TiO₂ nanosurface

Two new Ru(II)–/Os(II)–polypyridyl based sensitizer dyes with geminal dicarboxylic acid group as the binding unit for superior grafting of the dye to TiO₂ have been designed and synthesized. Steady-state photochemical studies of the two sensitizer dyes in presence of TiO₂ in water confirm strong binding of the dyes to TiO₂. Femtosecond transient absorption studies of these newly synthesized dyes on TiO₂ nanosurface have been carried out in water and the results have been compared with those for the corresponding 4,4′-dicarboxy-2,2′-bipyridine analogues of the dyes. While the charge recombination rates are considerably slower, interestingly, the electron injection rates are very fast for multiple saturated C–C linkages present between the chromophoric core and the anchoring moiety. The origin and the consequences of such profound effects on the ultrafast interfacial dynamics are discussed. This is the first report on the ultrafast transient absorption studies of dyes with geminal dicarboxylic acid binding groups, which we believe will add significantly to the present research efforts toward the development of robust and efficient dyes for use in dye solar applications

Red Light-Triggered CO Release from Mn₂(CO)₁₀ Using Triplet Sensitization in Polymer Nonwoven Fabrics

Applicability of phototherapeutic CO-releasing molecules (photoCORMs) is limited because they are activated by harmful and poorly tissue-penetrating near-ultraviolet light. Here, a strategy is demonstrated to activate classical photoCORM Mn₂(CO)₁₀ using red light (635 nm). By mixing in solution a triplet photosensitizer (<b>PS</b>) with the photoCORM and shining red light, energy transfer occurs from triplet excited-state ³<b>PS</b>* to a photolabile triplet state of Mn₂(CO)₁₀, which, like under near-UV irradiation, led to complete release of carbonyls. Crucially, such “triplet-sensitized CO-release” occurred in solid-state materials: when <b>PS</b> and Mn₂(CO)₁₀ were embedded in electrospun nonwoven fabrics, CO was liberated upon irradiation with low-intensity red light (≤36 mW 635 nm)

FRET-Based Probe for Monitoring pH Changes in Lipid-Dense Region of Hct116 Cells

A rhodamine conjugate (<b>L</b>) with a pseudo Stokes shift of 165 nm is used for probing changes in solution pH under physiological conditions. This reagent is found to be nontoxic, and the luminescence response could be used for imaging changes in endogenous pH induced by dexamethanose (DMT) in the endoplasmic reticulum

<span style="font-size:11.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-bidi-font-family: Mangal;mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language: HI" lang="EN-GB">Methane reforming with carbon dioxide over La-Ni_x-Ce_1-x mixed oxide catalysts</span>

478-483La-Nix-Ce1-x mixed oxide (0≤x≤1) catalysts have been hydrothermally prepared, characterized by physico-chemical techniques and evaluated for CO2 reforming of methane. High conversions are achieved <span style="mso-bidi-font-style: italic">for both methane and carbon dioxide over the LaNi0.6Ce0.4O3 catalyst tested under the conditions of CO2/CH4/N2 ratio of 80/80/80 (total flow rate = 240 mL/min), space velocity of 28,800 h-1 and at a temperature of 800 °C. The H2/CO ratio in the syngas is stable at 0.93±0.02. Exchanging Ni with Ce, rather than with La as reported in the literature, appears to be a better option for the improved performance of the catalysts. </span

Light-responsive paper strips as CO-releasing material with a colourimetric response

Carbon monoxide (CO) is known for its multifaceted role in human physiology, and molecules that release CO in a controlled way have been proposed as therapeutic drugs. In this work, a light-responsive CO-releasing molecule (CORM-Dabsyl) showed a strong colourimetric response upon photochemical CO-release, owing to the tight conjugation of a Mn(i) tricarbonyl centre to a dabsyl chromophoric ligand (L). Whereas the complex was very stable in the dark in nitrogen-purged aqueous media, CO-release was effectively triggered using 405 nm irradiation. CORM-Dabsyl, L and the inactive product iCORM-Dabsyl have been investigated by DFT and TD-DFT calculations. Only mild toxicity of CORM-Dabsyl was observed against LX-2 and HepaRG® human cell lines (IC50 ∼ 30 μM). Finally, to develop a CO storage and release material that is readily applicable to therapeutic situations, CORM-Dabsyl was loaded on low-cost and easily disposable paper strips, from which the light triggered CO-release was conveniently visible with the naked eye

Fluorinated Boronic Acid-Appended Pyridinium Salts and ¹⁹F NMR Spectroscopy for Diol Sensing

The identification and discrimination of diols is of fundamental importance in medical diagnostics, such as measuring the contents of glucose in the urine of diabetes patients. Diol sensors are often based on fluorophore-appended boronic acids, but these severely lack discriminatory power and their response is one-dimensional. As an alternative strategy, we present the use of fluorinated boronic acid-appended pyridinium salts in combination with ¹⁹F NMR spectroscopy. A pool of 59 (bio)­analytes was screened, containing monosaccharides, phosphorylated and <i>N</i>-acetylated sugars, polyols, carboxylic acids, nucleotides, and amines. The majority of analytes could be clearly detected and discriminated. In addition, glucose and fructose could be distinguished up to 1:9 molar ratio in mixtures. Crucially, the receptors feature high sensitivity and selectivity and are water-soluble, and their ¹⁹F-NMR analyte fingerprint is pH-robust, thereby making them particularly well-suited for medical application. Finally, to demonstrate this applicability, glucose could be detected in synthetic urine samples down to 1 mM using merely a 188 MHz NMR spectrometer