Mechanism of peak fronting in ion exclusion chromatography.

Evaluation of retention and selectivity for positional isomers in hydrophilic interaction liquid chromatography using a quantitative retention assessment approach.

Retention modeling of oligonucleotides on an amide-based HILIC column: A descriptor-driven approach.

Preparation and application of phenylboronic acid and ionic liquid functionalized silica stationary phase for HILIC/RPLC/IEC mixed mode chromatograph.

Evaluation and application of a chlorobenzimidazole bonded stationary phase for polyphenols separation in supercritical fluid chromatography.

The selective separation and precise analysis of rare earth elements (REEs) in impurity-laden matrices constitute persistent challenges. Among available separation techniques, ion-exchange chromatography has gained prominence as an effective approach for REE purification. However, the quest for a high-performance stationary phase preparation method continues to be a focal point. Herein, a propylsulfonic acid-functionalized stationary phase (Sil-SH-SCX) was developed through γ-mercaptopropyl trimethoxysilane (MPTS) grafting followed by oxidation. The Sil-SH-SCX demonstrated excellent chromatographic performance, achieving efficient separation of REEs with resolution ranging from 4.2 to 12.6 for adjacent lanthanides. Besides, the Sil-SH-SCX column displayed high repeatability (RSD < 0.99%, n = 10) and stability (RSD < 1.5%, n = 30). Taking advantage of its excellent separation performance, Sil-SH-SCX was successfully applied for the sensitive determination of REEs with excellent linearity (R2 = 0.996-0.999, 1-500mgL-1). This work provided an insight into the design of achromatography stationary phase and expanded its potential application in REE analysis and purification.

Facile preparation of new bidentate quaternary ammonium-type stationary phase for the separation of versatile analytes in hydrophilic interaction liquid chromatography.

Optimized protocol for high-efficiency mitochondrial RNA isolation from fission yeast in log phase and stationary phase.

A hyperbranched polymer-based stationary phase for hydrophilic interaction chromatography.

Chiral covalent organic frameworks (CCOFs) have potential application in enantioseparation due to their advantages, such as large surface area, abundant chiral recognition sites, and good chemical stability in organic solvents. However, due to the lack of essential active groups in COFs structures, it is challenging to introduce chiral ligands, which poses a challenge to the preparation and promotion of CCOFs. In this study, a strategy was developed to prepare CCOF@SiO2 core-shell microspheres for enantioseparation using the Ugi and click reactions. Imine-linked COF@SiO2 core-shell microspheres were synthesized in situ by using nonporous silica microspheres as the core and TAPB-DMTP-COF as the COF shell. This shell was formed by covalently conjugating 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxyterephthalaldehyde (DMTP). The carbon-carbon double bond was introduced into the COF framework through the Ugi multicomponent reaction in the presence of 4-pentenoic acid and cyclohexene isocyanate. The olefin-linked Ugi-COF@SiO2 microspheres were then reacted with thiolated chiral ligands such as β-CD-SH, captopril, and l-cysteine to produce CCOF@SiO2 core-shell microspheres via the "thiol-ene" click reaction. These CCOF@SiO2 microspheres were used as stationary phases to separate various racemic compounds in the normal phase and reversed-phase liquid chromatography modes. The columns with different chiral ligands showed excellent chiral recognition and separation capabilities for chiral compounds with good reproducibility. The successful applications highlight the potential of using the Ugi and "thiol-ene" click reactions to incorporate double bond active groups and different chiral ligands into the imine-linked COFs framework. This study's proposed strategy is versatile and offers a broad platform for the preparation and applications of CCOFs in enantioseparation.

Membrane structural properties in Staphylococcus aureus are tuned by the carotenoid 4,4'-diaponeurosporenoic acid.

Chirality plays a crucial role in pharmaceutical development, as enantiomers often display distinct therapeutic, pharmacokinetic, and safety profiles. Calcium channel blockers (CCBs), a cornerstone in antihypertensive therapy, frequently possess one or more chiral centers, making enantioselective analysis essential for pharmacological and regulatory accuracy. Despite growing evidence of stereoselective differences, most marketed CCBs remain available as racemates, underscoring the need for refined analytical approaches. This review aims to bridge that gap by critically synthesizing advances in analytical, bioanalytical, and regulatory strategies for chiral CCBs. Key separation platforms-including high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), gas chromatography (GC), and supercritical fluid chromatography (SFC)-are evaluated with emphasis on chiral stationary phases such as polysaccharides, cyclodextrins, macrocyclic antibiotics, and crown ethers. Recent innovations in hyphenated mass spectrometry, spectroscopic techniques, and eco-friendly miniaturized systems are highlighted for their ability to enhance enantioselectivity, reduce solvent consumption, and improve sensitivity in complex matrices. Case studies illustrate the pharmacokinetic and pharmacodynamic relevance of individual enantiomers, reinforcing the clinical impact of chirality in CCB therapy. The review concludes by identifying current limitations and exploring future directions, including AI-assisted selector design, green chemistry integration, and lab-on-chip platforms to advance personalized antihypertensive treatment.

Designing tailored stationary phase materials is essential for extending chromatographic techniques from conventional molecular systems to the separation of (nano)particles. In this work, we investigate key aspects of the design of stationary phase materials using silica supraparticles. Supraparticles are defined spherical aggregates of sub-micron sized primary particles, which provide tunable pore sizes and thus form a variable model system to elucidate structure-property relations for the size-exclusion chromatography of colloidal nanoparticles. We fabricate supraparticles with tunable pore sizes (70-200nm) and particle sizes (13-25μm) and systematically enhance their mechanical stability through high-temperature sintering and binder reinforcement to ensure stability upon packing. Using gold nanoparticles (5-100nm) as model analytes, we demonstrate pore size-dependent elution behavior, quantify accessible pore volume via the dimensionless distribution coefficient, and investigate the role of pore size and supraparticle size on column efficiency. We further demonstrate effective separation of nanoparticles from molecular impurities and agglomerates, as well as partial to near-complete separation of binary nanoparticle mixtures depending on their size differences. Moreover, we analyze the packing structure inside columns using X-ray micro-computed tomography, revealing packing defects as a key cause of moderate performance, underscoring the importance of optimized packing protocols. Using supraparticles as a versatile model system, our work offers practical insights into the design of tunable stationary phase materials for efficient nanoparticle separation via chromatography.

Supercritical fluid chromatography hyphenated with dielectric barrier discharge ionization mass spectrometry: A universal approach to analysis of complex plant extracts.

Two-step in situ growth strategy for green fabrication of hydrophilic FeOOH modified COF stationary phase with versatile separation capabilities

The milk fat globule membrane increases bacterial serotonin and exopolysaccharide production for maintenance of intestinal cell differentiation.

Rho is a conserved, ATP-dependent RNA translocase that terminates transcription at hundreds of sites across bacterial genomes. Although the molecular mechanism of Rho-dependent termination is well characterized, its spatial interplay with RNA polymerase (RNAP) within bacterial cells remains elusive. To address this question, we constructed intragenic, in-frame fusions inserting mCherry or sfGFP 48 amino acid residues downstream of the N-terminus of Rho in Salmonella. Strikingly, mCherry-but not sfGFP-renders the first 48 residues of Rho dispensable. RhoΔ48::mCherry is viable in single copy and exhibits wild-type termination activity invitro, whereas the full-length Rho::sfGFP fusion, although viable, slows growth and shows strongly reduced activity. Structured illumination microscopy (SIM) revealed that, despite these functional differences, both constructs exhibit similar localisation patterns relative to fluorescently tagged RNAP in single cells. During exponential growth, both Rho and RNAP form discrete clusters, but with markedly distinct spatial organisations: RNAP clusters associate with the nucleoid, whereas Rho is distributed throughout the cell body. This spatial partitioning persists in stationary phase, where RNAP becomes diffusely associated with a compacted nucleoid while Rho accumulates at the cell periphery. The widespread distribution of Rho at cytoplasmic locations is unexpected and suggests participation in cellular functions beyond its canonical role in transcription termination.

Extraction and chromatographic purification of purpurin: A scalable approach using modified dry column vacuum chromatography.

Abstract We compute a Hirzebruch-Riemann-Roch type formula for the invariant Riemann-Roch number of a quantizable Hamiltonian S 1 $S^1$ upper S Superscript 1 -manifold ( M , ω , J ) $(M,\omega ,{ \mathcal J})$ left parenthesis upper M comma omega comma script upper J right parenthesis , allowing 0 $0$ 0 to be a singular value of the moment map J : M → R ${ \mathcal J}:M\to {\mathbb R}$ script upper J colon upper M right arrow double struck upper R . Our formula represents an instance of the Guillemin-Sternberg principle, which states that quantization should commute with reduction. The conceptual novelty of our result is that the involved reduced system only depends on the symplectic data of M . To establish this, we derive a complete singular stationary phase expansion of the Witten integral without appealing to any kind of desingularization. As a consequence, our formula expresses the invariant Riemann-Roch number purely in terms of symplectic invariants of the singular symplectic quotient. In particular, it involves a new explicit symplectic invariant of the singularities.

Under nutrient limitation or stress, ribosome hibernation factors inactivate and protect ribosomes. Although ribosome hibernation plays an important role in microbes, we lack a complete understanding of this process in archaea. Here, we identify a family of hibernation factors, which we designate as single ribosomal subunit inhibitors (SriA-SriD), from the methanogenic archaeon Methanosarcina acetivorans. All four sri genes are encoded in an operon and each Sri protein inhibits protein synthesis in vitro. Deletion of sri genes in M. acetivorans impaired growth recovery after prolonged stationary phase and also led to depletion of the small ribosomal subunit. Cryo-EM structures show that Sri proteins bind to the ribosome in tandem and form conserved protein-protein interfaces. Sri is broadly distributed across archaeal phyla and sri genes frequently co-occur. Together, these findings establish Sri proteins as a distinct group of hibernation factors that protect ribosomes during dormancy and expand our understanding of ribosome hibernation in archaea.