Chemistry

This study aims to evaluate the therapeutic potential of phloretin–chitosan nanoparticles (Ph-ChNPs), alone and in combination with the anticancer drug tamoxifen, in modulating breast cancer markers and improving in vivo treatment outcomes. Ph-ChNPs were prepared by ionic gelation in the presence of Tripolyphosphate (TPP) solution as a crosslinker agent. The nanoparticles were characterized using DLS, TEM, UV-VIS and FT-IR spectroscopy. In vitro cytotoxic assay of Ph-ChNPs on MCF-7 breast cancer cell lines revealed anticancer activity with an IC₅₀ value of 32.12 ± 1.63 µg/mL. In vivo studies were carried out on mice, treated with DMBA to induce breast cancer and followed the effect of the prepared nanoparticle, either alone or with combination with tamoxifen, on mice health. The biochemical parameters measured after treatment with Ph-ChNPs alone showed an improvement in lipid profile with decreased total cholesterol (TC) and Triglyceride (TG) levels and increased HDL-c levels. Ph-ChNPs significantly reduced IL-6 and cyclin D1 levels, with a slight increase in cyclin E2 levels. Antioxidant enzyme levels were improved, and oxidative stress markers were reduced. The combination treatment showed a synergistic effect in reducing inflammation and cell proliferation. DMBA-injected mice had substantially increased BRCA1 and BRCA2 gene expression. Ph-ChNP-treated mice showed well-organized mammary gland structures, while DMBA-injected mice displayed dense tumor cell aggregations. Ph-ChNPs and tamoxifen treatments improved histopathological variations, with the combination treatment showing significant apoptosis of tumor cells. This study demonstrates the significant potential of Ph-ChNPs combined with tamoxifen in breast cancer treatment. The combination therapy effectively reduces tumor growth, induces apoptosis and modulates critical breast cancer markers, offering a promising therapeutic strategy. Full article

Degenerate third-order nonlinear optical (NLO) responses of organic molecules have a wide range of applications in science and engineering because they relate to the intensity-dependent refractive index (IDRI) and nonlinear absorption (NLA), such as two-photon absorption (TPA). Among the many molecular systems, open-shell molecular species such as intermediate singlet diradicaloids have attracted considerable attention because of their enhanced response, predicted theoretically by Nakano et al. Experimental studies for proofing and evaluating the enhanced nonlinearities play an important role in the development of the field. This tutorial review provides the solid fundamentals of the NLO processes of open-shell molecular species even to those who are not familiar with the experimental works. Its scope ranges from the basics of NLO responses, definitions, and interrelations of the key parameters of the responses, such as hyperpolarizability and TPA cross-section, to the experimental techniques used to evaluate them. Including the recent achievements, the evolution of experimental works on the TPA properties of singlet diradicaloids is also reviewed according to families of molecular structures. Full article

Nitric oxide (NO) is an important messenger molecule in almost all organisms. The diverse biological activities of NO have initiated in-depth research on the development of exogenous NO donors. Light-controlled NO donor can transport NO to specific areas to treat various diseases; thus, light–triggered NO donors are rapidly becoming an important class of compounds for the design of novel potential drugs. This review highlights the recent development of organic small molecule-based light-triggered NO donors and focuses on visible/red/NIR light-mediated NO donors. It contains rational designs of NO donor, NO releasing mechanism and detection, as well as its biological applications. Finally, the advantages, drawbacks, and challenges of this strategy are discussed in view of practical applications. Full article

Foam quality is an important index for judging the quality of beer. In this experiment, the interaction between PZ and iso-α-acid extracted from hops and its effect on beer foam production were investigated. According to the results of fluorescence titration experiments, the stoichiometric number ratio of PZ interacting with iso-α-acid was 3.91 ± 0.39, and the binding constant K was (2.16 ± 0.23) × 10⁵ M⁻¹. According to the results of molecular dynamics simulations, the binding sites of iso-α-acid in PZ were Leu-396, Ser-292 and Lys-290. The secondary structure of PZ was altered by the addition of iso-α-acid, and the percentage of β-sheets increased from 21.75% to 29.74%. which increased the protein’s flexibility, leading to enhanced foaming, stability, and texture of the foam. Full article

To ensure high-quality honey, and to delay crystallization or fermentation, honey is subjected to heat treatment. The heating process, as well as the duration and storage conditions, can lead to an increased level of 5-HMF (5-hydroxymethylfurfural), which exhibits numerous adverse effects on human health. The objective of the present study was to evaluate the evolution of 5-HMF levels in different varieties of honey from Romania, thermally treated at different temperatures between 45 and 75 °C. Both classical spectrophotometric methods, such as White and Winkler methods, and two modified simpler methods were used. The methods were compared based on their analytical reactions and analytical parameters such as linearity, LOD and LOQ, sensitivity, accuracy, and precision. The best-performing method was the one that employed thiobarbituric acid. The level of 5-HMF in the control samples and samples treated at 45 °C are below the limits accepted by the legislation (40 mg/kg). At higher temperatures, such as 55–65 °C, the values in some honey species, especially polyfloral species, already exceed the accepted threshold (57.5 ± 0.7 mg/kg; 98.8 ± 4.6 mg/kg) whereas at 75 °C, the 5-HMF level is very high (142.8 ± 8.7 mg/kg; 453.8 ± 51.3 mg/kg). The results obtained indicate that 5-HMF level increases gradually with temperature and is variety dependent. Full article

Near-UV circular dichroism (CD) spectroscopy is a widely used method that provides, among others, information about the tertiary structure of biomolecular systems such as proteins, RNA, or DNA. Experimental near-UV CD spectra of proteins reflect the CD signals averaged over the many conformations that these systems can adopt. Theoretical approaches have been developed to predict such spectroscopic properties and link modeled conformations of complex biosystems to easily accessible experimental data, without having the resort to costly structural biology techniques. However, these predictions are mostly generated on the basis of a single experimental structure, missing the dynamic information reflecting the protein conformational variability. Here, we describe a complete reformulation of the theoretical foundations behind the prediction of CD spectra. We propose a QM/MM-based automated pipeline that generates an average near-UV CD spectrum from a given MD ensemble in a fast manner based on these theoretical considerations and further test it on protein systems. This pipeline has been implemented in an open-source program called DichroProt. Full article

Cyclacenes with the general formula C_4nH_2n are cyclic analogs of acenes. Acenes are well-known for their high reactivity, which increases with the number of fused benzene rings. The cyclic strain, absence of a Clar sextet, and diradical or polyradical nature are expected to render cyclacenes highly reactive under ambient conditions. Their primary decomposition pathway is anticipated to involve dimerization or polymerization. We explore the reaction pathway of the [_π4_s + _π4_s] dimerization of [n]-cyclacenes for 6 ≤ n ≤ 20 by density functional theory (DFT) using spin-unrestricted and thermally-assisted-occupation (TAO) formalisms. Computational analysis predicts a stepwise reaction mechanism that starts with the formation of a van der Waals complex and proceeds through a transition state to an intermediate with a single new C–C bond and two unsaturated valences. A subsequent second transition state results in the formation of the dimerization product. However, for smaller cyclacenes (n < 10), neither the van der Waals complex nor the first transition state is involved, and the intermediate is formed without a barrier. The largest [20]-cyclacene investigated exhibits the highest barriers for these processes. However, with a barrier as low as 3.9 kcal/mol at the UB3LYP-D3(BJ)/6-31G(d) level of theory, dimerization is anticipated to occur very rapidly. Full article

Biomaterials and biomembranes play a crucial role in a variety of applications, particularly in the medical field due to their ability to mimic natural biological structures and functions. Crosslinkers play also an important role in enhancing the structural integrity and functionality of biomaterials and in the design of biomembranes. This review article explores the fundamentals of biomaterials and biomembranes, with a particular focus on the role of crosslinkers in biology, chemistry and medicine. We explore the various types of crosslinkers commonly used in biomaterials synthesis, examining their chemical structure, classification, and synthesis methods. Additionally, we analyze the biological properties of crosslinkers and their interactions, highlighting their biological impact, particularly in cellular behavior and cytotoxicity. This article further emphasizes recent advances and innovation, particularly in tissue engineering, drug delivery, and wound healing. Finally, we conclude by addressing current challenges and suggesting potential futures directions for research in this field. Full article

A plasma-assisted electrochemical deposition (PAECD) technology was introduced to coat a cast iron brake disc for the possible reduction of brake wear and brake wear particle (BWP) emission. The majority of the coating consisted of alumina (Al₂O₃), determined by energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) analysis. To validate the above strategy of the coating technology for automotive brake corners, one brake stock rotor was replaced by a PAECD-coated rotor for a vehicle road test. After the road test, weight loss of the brake components (rotors and pads) was measured, showing that the alumina coating can reduce the brake wear by more than 70%. BWPs were also collected from wheel barrels, spokes, and brake friction rings of the coated and uncoated rotors during the road test. A morphology and chemical composition analysis of the collected BWPs indicated that the coating could reduce BWP generation from the original sources and avoid a metal pick-up (MPU) issue, leading to less metallic content in BWPs. This alumina coating may provide the auto sector with a sustainable approach to overcome the brake dust emission problem, evidenced by less wear of the brake pads, minimal wear of the coated brake rotor, less MPUs, and a clean wheel rim on the coated brake corner. Full article

Proline is considered the model organocatalytic amino acid. However, other naturally occurring amino acids remain a potent and perhaps overlooked source of organocatalytic potential. In this work, we investigated the capacity of various natural amino acids to promote enantioselectivity in a synthesis of warfarin. We have identified L- and d-arginine as enantioselective catalysts for this reaction and have developed a recrystallization method to isolate the enantiomers of warfarin with high enantiopurity. In addition, we used methylated derivatives of arginine to provide insight into the reaction mechanism. Full article

This study presents a comprehensive analysis of the chemical composition and bioactive properties of six newly cultivated varieties of pigmented and non-pigmented rice: Neunkeunheukchal (NKH), Neunkeunssal, Heukjagwang 709 (H709), Heukjagwang 1601, Hongjinju, and Hongchapssal (HCS). This study aims to characterize the chemical information and the industrial potential of lesser-known rice varieties. Significant differences were observed in the levels of phenolic compounds, flavonoids, γ-oryzanol, and free amino acids among these varieties, correlating with their antioxidant capacities. Among these varieties, NKH consistently exhibited the highest total phenolic, flavonoid, and γ-oryzanol contents, along with the strongest radical-scavenging activities, indicating its potential as a valuable functional food ingredient. Additionally, H709 and HCS demonstrated significant antioxidant activities, highlighting their potential roles in health-promoting applications. These findings highlight the potential of these varieties for functional food and nutraceutical applications. Future research should investigate the effects of cultivation conditions and processing methods on bioactive compound levels while conducting clinical trials to validate these health benefits in human models. The findings suggest that NKH, given its rich bioactive profile, may be particularly effective in managing oxidative stress and associated chronic diseases. Furthermore, the γ-oryzanol contents, the highest in NKH, highlight its potential for metabolic health benefits. This study lays the groundwork for future investigations into the development of functional foods and nutraceuticals derived from the unique characteristics of pigmented and non-pigmented rice varieties. Full article

The complexation behavior of lanthanide(III) ions with terephthalic acid (1,4-benzene-dicarboxylic acid) in 0.01 M KNO₃ aqueous solutions was studied across a broad pH range and at two metal-to-ligand ratios using potentiometric titration combined with photoluminescence spectroscopy. Chemometric analysis of titration curves enabled the determination of relative molar fractions, stability constants, and probable stoichiometry of the formed complexes. In solutions with a 1:2 metal-to-ligand ratio, bis-complexes (two terephthalate ligands per lanthanide ion) predominated, while ligand-rich conditions favored the formation of tetra-complexes (four ligands per metal ion). In alkaline media, bis-complexes transform into mixed hydroxy-terephthalate species. Meanwhile, for the tetra-complexes, the addition of NaOH results in the formation of lanthanide ion hydroxo complexes without organic ligands. The structural diversity of these complexes, driven by the terephthalate ligand’s tendency to maximize denticity, suggested dimeric or oligomeric configurations. The stability constants and structural features of complexes in solution were found to align with those of known solid-state lanthanide–terephthalate polymers, highlighting their potential as models for polymeric structures. Full article

The electronic and phonon bands of Skaergaardite are investigated using density functional theory (DFT) as implemented in Quantum ESPRESSO. Skaergaardite is a copper palladium mineral (CuPd) found in the Skaergaard intrusion with a CsCl-type (B2) structure. Due to its porous structure, it presents a large surface area available for interactions, which makes it a promising catalyst. The PBE-GGA functional with a Hubbard-like localized term (DFT+U) is combined with ultrasoft and norm-conserving pseudopotentials, and a conventional approach with a dense Monkhorst–Pack grid of k-points 12 × 12 × 12 is applied. The electronic valence bands are mainly constituted by 3d orbitals of Cu and 4d orbitals of Pd and a pseudo-gap can be recognized. With respect to DFT, DFT+U causes a general downward shift in the valence band. The acoustic and optical phonon branches are separated by a few cm⁻¹ gap at about 150 cm⁻¹ and show a density of state curve typical of ordered materials. These results highlight the reliability of DFT+U in studying bimetallic systems with scarce experimental benchmarks, offering insights into the behavior of Skaergaardite and its potential applications in material science such as reduction reactions and hydrogen storage. Full article

Carbon-based materials have garnered significant attention for electrocatalysis applications in fuel cells due to their unique structural and electronic properties, but rapid oxygen reduction reaction (ORR) at the cathode of fuel cells is challenging. Dopants are typically used as active sites for ORR, and increasing the number of active sites for carbon-based catalysts remains a challenge. Here, we carried out first-principles calculations for the electrocatalytic ORR performance of the recently reported monolayer superconductors of carbon-rich selenides. Remarkably, the abundant C atoms serve as the active centers instead of the foreign atoms (Se). All the free energy changes during the ORR process are downhill, suggesting that these carbon-rich selenides hold promise as metal-free electrocatalysts for ORR. Note that the promising electrocatalytic performance of carbon-rich selenides is theoretically predicted; validation is encouraged for experimental efforts. Full article

Microbiologically influenced corrosion (MIC) is one of the key causes of material failure in marine engineering, and sulfate-reducing bacteria (SRB) and iron-oxidizing bacteria (IOB) are typical representatives of anaerobic and aerobic microorganisms, respectively. These microorganisms are widely present in marine environments and can form synergistic communities on the surface of metal materials, posing a corrosion threat to them. At the same time, the presence of mixed bacteria may have an effect on cathodic protection, so this study investigates the growth metabolism of mixed SRB and IOB under different cathodic protection potentials in an impressed current cathodic protection (ICCP) system in a marine environment containing SRB and IOB. It also examines the attachment of these microorganisms to the anode and cathode, and the impact on cathodic protection efficiency. The results indicate that in a marine environment containing IOB and SRB, the cathodic protection efficiency of the ICCP system increases with the negative shift of the protection potential. A more positive cathodic protection potential promotes the adhesion of mixed bacteria on the electrode surface and the formation of a biofilm, which reduces cathodic protection efficiency. In contrast, at a cathodic protection potential of −1.05 V (SCE), bacterial growth is inhibited, and a dense crystalline corrosion film primarily composed of Fe₂O₃ and Fe(OH)₃ forms on the cathode surface. This film effectively protects the cathodic metal, significantly mitigating MIC. Full article

As examples of “Click Chemistry”, the reaction of 1-(oxiran-2-ylmethyl)piperidine with several 1,2,4-triazoles derivatives was studied. As a result, the reaction shows that the oxirane ring opens regiospecifically, according to Krasusky’s rule, without using a catalyst. The basic nitrogen present in 1-(oxiran-2-ylmethyl)piperidine has a catalytic (anchimer) effect. Full article

The present work represented results from a comprehensive study of free radicals and the antioxidant properties of irradiated walnuts. The effects of gamma irradiation on free radical generation and their stability, as well as on the antioxidant activity in walnuts, were investigated by Electron Paramagnetic Resonance (EPR) spectroscopy, Oxygen Radical Absorbance Capacity (ORAC), and Hydroxyl Radical Antioxidant Capacity (HORAC) assays. Walnut samples were irradiated using ⁶⁰Co at two different doses: 10 and 25 kGy. As a marker for the identification of high-energy radiation treatment, characteristic cellulose radical signals were detected after irradiation and remained observable for over eight months. A significant increase in antioxidant activity was observed at higher irradiation doses, as measured by DPPH free radical scavenging activity, ORAC and HORAC assays. Full article

Multiple reduced π-conjugated hydrocarbons exhibit π-electron conjugation modes different from neutral species due to the distinct number of electrons. Herein, we report the generation of a 32 π-electron tetraanion of a derivative of a doubly cyclic π-conjugated system with 28 π-electrons, tetracyclopentatetraphenylene (TCPTP), through an exhaustive reduction with potassium. Although aggregation causes some complications, based on spectroscopic and theoretical investigations, it is revealed that negative charges are located at the outer and inner peripheries, suggesting that the tetraanion adopts a globally delocalized double annulenoid (annulene-within-an-annulene, AWA) mode, with 22 π-electron outer and 10 π-electron inner aromatic perimeters. On the other hand, excess charges of the outer perimeter are mainly located at the apical position of the pentagonal rings, indicating a significant contribution of the cyclopentadienide form. The theoretical analysis of magnetically induced ring current tropicities reveals counter-rotating ring currents at the outer and inner rings, supporting the predominant contribution of the cyclopentadienide form. Full article

Benzimidazolinones exhibit unique biological activities and serve as building blocks in synthesizing pharmaceutical compounds. Although multiple synthetic approaches involving intermolecular cyclization reactions have been reported, intramolecular cyclization reactions are scarce, and more rational synthetic methods are required. Hypervalent iodine-catalyzed oxidative C–N coupling is a potentially effective approach for synthesizing benzimidazolinones under metal-free conditions. In this study, we present a method utilizing hypervalent iodine catalysis for the oxidative cyclization of N’-aryl urea compounds, resulting in the first metal-free synthesis of various benzimidazolinones. Full article