A Fast HPLC/UV Method for Determination of Ketoprofen in Cellular Media

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A Fast HPLC/UV Method for Determination of Ketoprofen in Cellular Media

A simple, sensitive and quick HPLC method was developed for the determination of ketoprofen in cell culture media. Separation was performed using a gradient on a C18 column with a mobile phase of acetonitrile and acidified miliQ water. The method was validated for linearity, accuracy, precision, limit of quantitation, limit of detection, as well as for robustness. The described method is applicable for determination of various pharmacokinetic aspects of ketoprofen in vitro.


Abstract

A simple, sensitive and quick HPLC method was developed for the determination of ketoprofen in cell culture media (EMEM, DMEM, RPMI). Separation was performed using a gradient on the C18 column with a mobile phase of acetonitrile and miliQ water acidified by 0.1 % (v/v) formic acid. The method was validated for parameters including linearity, accuracy, precision, limit of quantitation and limit of detection, as well as robustness. The response was found linear over the range of 3–100 μg/mL as demonstrated by the acquired value of correlation coefficient R2=0.9997. The described method is applicable for determination of various pharmacokinetic aspects of ketoprofen in vitro.

Brownmillerite Calcium Ferrite, a Promising Perovskite‐Related Material in the Degradation of a Tight Dye under Ambient Conditions

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Brownmillerite Calcium Ferrite, a Promising Perovskite-Related Material in the Degradation of a Tight Dye under Ambient Conditions

Synthesized and characterized brownmillerite type Ca2Fe2O5 nanoparticles degrade Alizarin Red S (ARS) quinone dye in the darkness, making it a promising material for the degradation of not only ARS but of other persistent dyes, too.


Abstract

Evaluation of effective and low-cost materials as catalysts to combat the threat of pollution is a significant and growing trend. With this aim, we have synthesized calcium ferrite brownmillerite by wet preparation approach as a catalyst for pollution. The structural analysis is established by the X-ray diffraction of Ca2Fe2O5, whereas the tetrahedral and octahedral sites band stretching for ferrite specimen has been deduced using FTIR. The bandgap energy has been estimated by the Tauc relation (2.17 eV). Ca2Fe2O5 brownmillerite exhibits a BET surface area of 10 m2/g and a BJH pore volume of 0.121 cm3/g with the average particle size of 70 nm. Importantly, the alizarin Red S dye degradation has been studied using the prepared ferrite catalyst, under dark ambient conditions and without the presence of any acidic or basic additives. Degradation is also supported by both FTIR and TOC analysis. Surface properties of brownmillerite Ca2Fe2O5 have been characterized using electronic spectroscopy and CO2 temperature programmed desorption (TPD) analysis and revealed that the basic surface of brownmillerite Ca2Fe2O5 offers active sites that are suitable for degradation processes. All results show that the preparation of brownmillerite Ca2Fe2O5 via the Pechini method is suitable to produce fine surfaces and pores with nanosized particles.

Intramolecular CH‐Hydrogen Bonding During the Dissociation of the Oxaphosphetane Intermediate Facilitates Z/E‐Selectivity in Wittig Olefination

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Intramolecular CH-Hydrogen Bonding During the Dissociation of the Oxaphosphetane Intermediate Facilitates Z/E-Selectivity in Wittig Olefination

The Z-selective synthesis of novel nitrostilbenes has been reported. An intrinsic role of intramolecular hydrogen bonding during the dissociation of OPA-intermediate is critical for the stereoselective Wittig olefination. DFT calculations and X-ray measured intramolecular CH hydrogen bonding distances strongly support the observed phenomenon. Further, the current methodology has been utilized to synthesize medicinally potential salicylate-methyl-ester-based 2-arylindole derivatives.


Abstract

Herein, DFT studies corroborating experimental results revealed that the shortest intramolecular hydrogen bonding distance of cis/trans-oxaphosphetane (OPA) oxygen with the CH-hydrogen of a triphenylphosphine phenyl ring provides good evidence for the attained olefin Z/E-selectivity in Wittig olefination of the studied examples. 2-Nitrobenzaldehyde, 3-nitrobenzaldehyde, 2-nitro-3-bromobenzaldehyde, 2-nitro-5-bromobenzaldehyde and 2-nitro-5-arylbenzaldehydes provided Z-nitrostilbenes with (2-chloro-4-hydroxy-3-methoxy-5-(methoxycarbonyl)benzyl) triphenylphosphonium chloride as the major products. However, 4-nitrobenzaldehyde and 2-nitro-6-bromobenzaldehydes furnished E-nitrostilbenes as the major products in high yields. Furthermore, the DFT computed intramolecular CH1/CH2-hydrogen bond distances with Cl/NO2 of selected stilbene derivatives were in good agreement with intramolecular hydrogen bond distances measured from single-crystal X-ray diffraction measurements.

Bacterial hydrazine biosynthetic pathways featuring cupin/methionyl tRNA synthetase‐like enzymes

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Nitrogen-Nitrogen (N–N) bond-containing functional groups in natural products and synthetic drugs play significant roles in exerting biological activities. The mechanisms of N–N bond formation in natural organic molecules have garnered increasing attention over the decades. Recent advances have illuminated various enzymatic and nonenzymatic strategies, and our understanding of natural N–N bond construction is rapidly expanding. A group of didomain proteins with zinc-binding cupin/methionyl-tRNA synthetase (MetRS)-like domains, also known as hydrazine synthetases, generates amino acid-based hydrazines, which serve as key biosynthetic precursors of diverse N–N bond-containing functionalities such as hydrazone, diazo, triazene, pyrazole, and pyridazinone groups. In this review, we summarize the current knowledge on hydrazine synthetase mechanisms and the various pathways employing this unique bond-forming machinery.

Carbazole Based Smaragdyrins: Synthesis, Aromaticity Switching, and Formation of a Spiro‐Dimer

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Carbazole-incorporated smaragdyrin BF2-complex 3 was synthesized by SNAr reaction of 3,5-dibromo-8-mesityl-BODIPY 1 with 3,6-di(tert-butyl)-1,8-di(pyrrol-2-yl)carbazole 2 as a nucleophile. Demetalation of 3 with ZrCl4 gave the corresponding smaragdyrin free base 4 in a good yield. Oxidations of 3 and 4 with MnO2 gave smaragdyrins 5 and 6, respectively, both followed by aromaticity switching, since the oxidized products showed a moderate paratropic ring current owing to their 20π-electronic circuits. Further, treatment of 4 with [RhCl(CO)2]2 in the presence of NaOAc gave RhI complex 7, and oxidation of 3 with RuCl3 in the presence of triethylamine led to the formation of a spiro dimer product, 8.

Design, Synthesis, and Characterization of Novel Styryl Dyes as Fluorescent Probes for Tau Aggregate Detection in Vitro and in Cells

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Design, Synthesis, and Characterization of Novel Styryl Dyes as Fluorescent Probes for Tau Aggregate Detection in Vitro and in Cells

Novel styryl dye derivatives incorporating indolium and quinolinium cores are synthesized to examine their binding capability with tau aggregates. These dyes possess enhanced fluorescence in viscous environments. Among them, Dye 4, containing a quinolinium moiety, shows the most outstanding increase in fluorescence upon binding to tau aggregates in vitro and in cells. These probes exhibit potential for Alzheimer's disease detection.


Abstract

A series of novel styryl dye derivatives incorporating indolium and quinolinium core structures were successfully synthesized to explore their interacting and binding capabilities with tau aggregates in vitro and in cells. The synthesized dyes exhibited enhanced fluorescence emission in viscous environments due to the rotatable bond confinement in the core structure. Dye 4, containing a quinolinium moeity and featuring two cationic sites, demonstrated a 28-fold increase in fluorescence emission upon binding to tau aggregates. This dye could also stain tau aggregates in living cells, confirmed by cell imaging using confocal fluorescence microscopy. A molecular docking study was conducted to provide additional visualization and support for binding interactions. This work offers novel and non-cytotoxic fluorescent probes with desirable photophysical properties, which could potentially be used for studying tau aggregates in living cells, prompting further development of new fluorescent probes for early Alzheimer's disease detection.

Sodium‐Mediated Reductive C−C Bond Cleavage Assisted by Boryl Groups

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Sodium-Mediated Reductive C−C Bond Cleavage Assisted by Boryl Groups

Boryl-group-assisted reductive C−C bond cleavage of 1,2-diaryl-1,2-diborylethanes is described. The substrates, 1,2-diaryl-1,2-diborylethanes, are synthesized by reductive diboration of stilbenes. The combination of these reactions, reductive diboration and reductive cleavage provides a new strategy for reductive C=C double bond cleavage.


Abstract

In contrast to the well-established oxidative C=C double bond cleavage to give the corresponding carbonyl compounds, little is known about reductive C=C double bond cleavage. Here we report that C−C single bond cleavage in 1,2-diaryl-1,2-diborylethanes proceeds by reduction with sodium metal to yield α-boryl benzylsodium species. In combination with our previous reductive diboration of stilbenes, the overall transformation represents reductive cleavage of the C=C double bonds of stilbene to yield α-boryl-α-sodiated toluenes. This reductive two-step C=C double bond cleavage is applicable to ring-opening or ring-expansion reactions of polycyclic aromatic hydrocarbons.

Colloidal Plasmonic Metasurfaces for the Enhancement of Non‐Linear Optical Processes and Molecular Spectroscopies

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Colloidal Plasmonic Metasurfaces for the Enhancement of Non-Linear Optical Processes and Molecular Spectroscopies

Recent developments in colloidal-based plasmonic metasurfaces unlocked new opportunities for the application of these highly dynamic systems to non-linear optical phenomena and molecular spectroscopies. This Minireview summarizes potential advantages and current challenges of colloidal systems for the enhancement of second and third order light-matter interactions and offers a critical perspective on their potential impact on the next generation of photonics metamaterials.


Abstract

Colloidal metasurfaces are emerging as promising candidates for the development of functional chemical metamaterials, combining the undisputed control over crystallography and surface chemistry achieved by synthetic nanochemistry with the scalability and versatility of colloidal self-assembly strategies. In light of recent reports of colloidal plasmonic materials displaying high-performing optical cavities, this Minireview discusses the use of this type of metamaterials in the specific context of non-linear optical phenomena and non-linear molecular spectroscopies. Our attention is focused on the opportunities and advantages that colloidal nanoparticles and self-assembled plasmonic metasurfaces can bring to the table compared to more traditional nanofabrication strategies. Specifically, we believe that future work in this direction will express the full potential of non-linear molecular spectroscopies to explore the chemical space, with a deeper understanding of plasmon-molecule dynamics, plasmon-mediated processes, and surface-enhanced chemistry.

Hexagonal Boron Nitride Spacers for Fluorescence Imaging of Biomolecules

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Hexagonal Boron Nitride Spacers for Fluorescence Imaging of Biomolecules

We employ few-layer hexagonal boron nitride (hBN) as a precisely tailorable fluorescence spacer between rhodamine-labelled phosphatidylethanolamine lipid (Rh-PE) membranes and graphene substrates on SiO2/Si substrates. The pre-determined hBN thicknesses can be employed to control the non-radiative energy transfer properties of graphene, with fluorescence quenching following a d −4 distance-dependent behaviour.


Abstract

Fluorescence imaging is an invaluable tool to investigate biomolecular dynamics, mechanics, and interactions in aqueous environments. Two-dimensional materials offer large-area, atomically smooth surfaces for wide-field biomolecule imaging. Despite the success of graphene for on-chip biosensing and biomolecule manipulation, its strong fluorescence-quenching properties pose a challenge for biomolecular investigations that are based on direct optical readouts. Here, we employ few-layer hexagonal boron nitride (hBN) as a precisely tailorable fluorescence spacer between labelled lipid membranes and graphene substrates. By stacking high-quality hBN crystals in the 10–20 nm thickness range on monolayer graphene, we observe distance-dependent fluorescence intensity variations. Remarkably, with hBN spacers as thin as 20 nm, the fluorescence intensity is comparable to bare SiO2/Si substrates, while the intensity was reduced to 60 % and 80 % with ~10 nm and ~16 nm hBN thicknesses respectively. We confirm that pre-determined hBN thicknesses can be employed to control the non-radiative energy transfer properties of graphene, with fluorescence quenching following a d −4 distance-dependent behaviour. This seamless integration of electronically active and dielectric van der Waals materials into vertical heterostructures enables multifunctional platforms addressing the manipulation, localization, and visualization of biomolecules for fundamental biophysics and biosensing applications.