Search Results (88)

Background/Objectives: Polysaccharide-protein conjugate vaccines have proven highly effective, yet they remain limited by manufacturing complexity, cost, and variable performance across serotypes, while carrier proteins can add unwanted immunological and production burdens. To address these constraints, we explored a carrier-protein-free conjugate vaccine concept in which a broadly MHC class II-binding helper epitope (PADRE) replaces the conventional protein carrier to provide T-cell help for a pneumococcal capsular polysaccharide antigen. Methods: Using serotype 15C CPS as a model, we generated CPS–PADRE conjugates and compared designs with or without a putative cleavable motif (RR) at the junction, alongside a conventional protein conjugate as a benchmark. Results: In mice, the CPS–protein conjugate induced the strongest CPS-specific IgG response, whereas CPS–PADRE conjugates elicited clear but overall lower antibody levels. Notably, incorporation of the cleavable motif did not improve immunogenicity and instead reduced humoral responses relative to the non-cleavable design. Conclusion: These findings support the feasibility of carrier-protein-free polysaccharide-peptide conjugate vaccines, while highlighting that cleavable junctions are not universally advantageous and must be empirically optimized for polysaccharide-helper epitope architectures. Full article

Pomegranate peel, accounting for 35–50% of the fruit weight, is an underutilized agri-food by-product. This study applied, for the first time, fermentation with Saccharomyces cerevisiae as a simple and sustainable strategy to simultaneously obtain tannin-rich extracts and polysaccharide fractions with potential prebiotic activity. Peels from two cultivars, Wonderful and G1, differing in peel thickness, were subjected to three fermentation protocols (air- and not air-exposed) and monitored at 25 °C over 48 and 72 h. HPLC-DAD analysis showed that yeast-inoculated fermentation increased total tannin concentration in dry extracts (up to 70%) without inducing chemical modifications to tannin profiles. As determined by Dynamic Light Scattering, fermentation promoted significant depolymerization of native polysaccharides, while DOSY-¹H-NMR analyses revealed the presence of reduced molecular weight fractions down to 26 kDa. In vitro growth assays confirmed that fermented polysaccharides were more efficiently utilized as a carbon source by Bifidobacterium breve and Lactiplantibacillus plantarum compared to non-fermented controls, likely thanks to polysaccharide depolymerization induced by fermentation. The study demonstrated that air-exposed S. cerevisiae fermentation was an effective process alternative to chemical or enzymatic hydrolysis for modifying pomegranate peel pectin directly within a complex matrix, while simultaneously enhancing tannin recovery. This approach represents a possible sustainable strategy for pomegranate peel valorization into functional ingredients. Full article

Poly(hexamethylene biguanide) (PHMB) is a polycationic antimicrobial polymer exhibiting broad-spectrum activity against bacteria, fungi, and viruses, and is widely used in medical settings for infection prevention and control. However, the relationship between chemical structure and antimicrobial activity remains unclear. In this study, we synthesised and characterised a series of polymeric biguanides with systematically varied alkyl chain lengths to examine the effects of structural variation on physicochemical properties and antimicrobial activity. H NMR spectroscopy and FTIR confirmed successful polymerisation. Solubility measurements revealed a progressive decrease in aqueous solubility with increasing alkyl chain length, consistent with increased hydrophobicity. Dynamic light scattering indicated reversible folding and unfolding of polymer chains in aqueous solution, with stabilisation at higher concentrations. Diffusion-ordered spectroscopy was used to calculate hydrodynamic diameters and polydispersity indices. Antimicrobial assays against Staphylococcus aureus and Pseudomonas aeruginosa showed that polymers containing heptamethylene and octamethylene chains exhibited the highest antibacterial activity, whereas tetramethylene- and pentamethylene-containing polymers showed greater fungicidal activity against Candida albicans. Highly hydrophobic polymers showed increased aggregation, resulting in reduced antimicrobial efficacy. Overall, these results indicate that both charge density and alkyl chain length are key determinants of antimicrobial activity. This polymeric biguanide series provides a platform for further investigation of structure–activity relationships and mechanisms of action against pathogenic microorganisms and their biofilms. Full article

Homogeneous Kolbe-Schmitt carboxylation of phenoxides offers a mild and effective alternative to the classical high-temperature solid-phase Kolbe-Schmitt reaction. To develop this into a practical synthetic approach, we investigated several fundamental dependencies, particularly the impact of cations (Na, K, Li, Cs, and Rb), phenoxide concentration, and solvents (DMSO or DMF) on the yield and regioisomeric ratio of hydroxyaromatic carboxylic acids (HACAs). We identified optimal conditions for the effective carboxylation of different phenoxides, including a chiral Ellman’s sulfinamide derived from ortho-vanillin. Both solvents and cations were found to be crucial in the carboxylation of phenoxides. Due to solvation effects, DMSO directs CO₂ attack to the para-position of phenoxide, while DMF, although less selective, generally affords higher HACA yields. The addition of equiv. amounts of mesitolate salt to phenoxide in either DMSO or DMF solution often drives the reaction to completion, resulting in yields of up to 98%. Phenoxides containing several EWG groups, such as halogens or alkyl groups, adjacent to the reaction center show considerably lower reactivity in carboxylation; however, by carefully adjusting parameters, acceptable conversions (>70%) can be achieved. Using the gasometry, we assessed the stability of phenoxide and mesitolate carbonate complexes in DMSO. These experiments revealed distinct stages for the onset of decomposition and carboxylation at atmospheric pressure, indicating a lower energy barrier in the homogeneous process. Further insight into carbonate complex behavior was obtained through DOSY and ¹³C NMR experiments, which support increased molecular association in solution and correlate with enhanced reactivity. Full article

Supramolecular nanoparticles offer an efficient strategy to enhance the solubility, stability, and bioavailability of poorly water-soluble therapeutic molecules. In this study, water-dispersible SNPs were successfully prepared from dicarboxyl-bis-pillar[5]arene (H) and cetyltrimethylammonium bromide (CTAB) using a microemulsion method. Dynamic light scattering revealed that the resulting CTAB/H nanoparticles possessed a size distribution centered around 40 nm, a positive surface charge (+15 mV), and exhibited high colloidal stability over three months. ¹H NMR, 2D TOCSY, 2D NOESY, diffusion ordered NMR spectroscopy, and UV-Vis investigations confirmed the inclusion of the CTAB alkyl chain within the pillar[5]arene cavity, supporting the formation of stable supramolecular assemblies capable of efficiently encapsulating the poorly water-soluble flavonol quercetin (Q). The CTAB/H system displayed low cytotoxicity (up to 50 µg/mL) and pronounced antioxidant activity, as evidenced by DPPH, ABTS, and FRAP assays. Quercetin-loaded nanoparticles (CTAB/H/Q) enhanced cellular uptake and exhibited a marked cytoprotective effect against H₂O₂-induced oxidative stress in NIH-3T3 fibroblasts. Full article

The macrolide antibiotic telithromycin was developed to avoid common antibiotic resistances, yet it has been recently withdrawn from the European market due to severe side effects. Both side effects and the effectiveness of a drug can be related to the strength of its interaction with human serum albumin (HSA). However, as of yet, interactions between telithromycin and HSA have not been thoroughly studied. In this work, we evaluate the interaction strength and structural details of telithromycin and HSA via diffusion ordered spectroscopy (DOSY) and transferred NOE measurements. The binding strengths are compared with those of related macrolides. Our results show that the interaction strength increases with the decreasing polarity of the side chains in the antibiotic. Among the tested macrolide antibiotics, telithromycin interacted the strongest with HSA. Structure calculations based on transferred NOEs, using DFT calculations, show that telithromycin adopts a specific conformation upon binding, which shields the polar moieties attached to the aglycon and enables more hydrophobic interactions with HSA. Full article

Reverse micelles (RMs) are versatile nanostructures traditionally formed in low-polarity organic solvents, but the need for greener alternatives has limited their broader applicability. Here, we demonstrate for the first time that a hydrophobic Natural Deep Eutectic Solvent (NADES), prepared from a simple 1:1 mixture of camphor and menthol (CM), can act as the continuous external phase for RM formation. Remarkably, CM dissolves the benchmark surfactant sodium dioctyl sulfosuccinate (AOT) at concentrations up to 0.5 M without co-surfactants and supports water solubilization up to W₀ = [H₂O]/[AOT] = 5, yielding thermodynamically stable systems. 1H and DOSY NMR analyses reveal clear structural rearrangements of the micellar interface, confirm the encapsulation of water in the polar core, and provide quantitative evidence of size modulation as a function of W₀. The resulting CM/AOT/water assemblies represent the first example of NADES-based reverse micelles, offering an easily prepared, sustainable, and biocompatible platform. This breakthrough opens new perspectives for the development of green self-assembled systems with promising applications in areas such as food technology, pharmaceuticals, and nanomedicine. Full article

The cationic chloro-P-{[4-(diphenylphosphanyl)phenyl]-N,N-dimethylmethanammonio(norbornadiene)rhodium(I) complex was encapsulated inside a self-assembled hexameric capsule. This capsule was obtained through a reaction involving 2,8,14,20-tetra-undecyl-resorcin[4]arene and water in chloroform. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible spectroscopy, ¹H, ³¹P{¹H} NMR and DOSY). The rhodium complex was evaluated in the [2+2+2] cycloaddition between N,N-dipropargyl-p-toluenesulfonamide and arylacetylene derivatives. In the presence of two equivalents of arylacetylenes in water-saturated chloroform at 60 °C for 24 h, the 4-methyl-N-(prop-2-yn-1-yl)-N-((2-tosylisoindolin-5-yl)methyl)benzenesulfonamide, the homocycloaddition product of 1,6-diyne is predominantly formed. In the presence of the supramolecular capsule, a selectivity inversion in favor of 5-aryl-2-tosylisoindoline is observed, with heterocycloaddition products formed in proportions between 53 and 69%. Full article

The [PdCl₂(cod)] complex was encapsulated inside a self-assembled hexameric capsule obtained via a reaction of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible, ¹H NMR and DOSY spectroscopies). The latter proved effective in the dimerization of styrene derivatives under mild conditions, with a catalyst loading of 0.5 mol% at 60 °C. Electronically enriched vinyl arenes underwent cyclization of the catalytic products, leading to the quasi-quantitative formation of indanes from 4-tert-butylstyrene and 9-vinylanthracene. In the instance of 9-vinylanthracene, the rearrangement product is tribenzo–pentaphene, which is formed in 50% of conversions. Full article

The complexation of nabumetone (NAB) and naproxen (NAP) with cucurbit[7]uril (CB7) was investigated in aqueous solution by isothermal titration microcalorimetry, mass spectrometry, NMR spectroscopy, and computation methods. High-resolution mass spectrometry was used for the determination of the binding stoichiometry and the gas-phase stability of the drug–CB7 complex. The doubly charged NH₄⁺ or Na⁺ adducts of the 1:1 complex were observed in the mass spectra. The dissociation of complexes was monitored at different collision energies, (1–16) eV, leading to the neutral loss of NH₃ and the drug, with charge retention observed on CB7. By performing ITC experiments, all the thermodynamic parameters were determined for the NAB-CB7 complex in water at 25 °C. The corresponding values amounted to the following: logK = 4.66 ± 0.01; Δ_rG° = −26.7 ± 0.1 kJ/mol; Δ_rH° = −20.2 ± 0.7 kJ/mol; TΔ_rS° = 6.4 ± 0.8 kJ/mol, i.e., the formation of the inclusion complex is enthalpy driven and has a favorable entropy. The inclusion phenomena were further confirmed by NMR spectroscopy (¹H, ROESY, and DOSY), suggesting the encapsulation of the naphthalene ring of both drugs inside the CB7 cavity. The results of the DFT calculations and the IGMH analysis were in accordance with the experimental ones, suggesting that van der Waals interactions play a major role in drug–CB7 complexation. Full article

Xanthones are a group of polyphenolic compounds widely known to have antitumor, anti-inflammatory, antibacterial, antifungal, antiviral, and antioxidant properties. To fully utilize their therapeutic potential, this study aimed to enhance the solubility of a poorly soluble xanthone by preparing a 1:1 molar ratio of xanthone–urea complex utilizing a cogrinding method via a vibration rod mill. DSC analysis revealed the disappearance of the characteristic endothermic peaks of xanthone (177 °C) and urea (136 °C) in the ground mixture (GM), along with the appearance of a new endothermic peak at 185 °C, indicating potential complexation. Additionally, new peaks were observed in the PXRD patterns of the GM at 9.1°, 12.0°, 14.0°, 18.6°, 19.6°, and 24.6°, suggesting structural changes that were also observed in SEM morphology. FTIR spectroscopy revealed significant shifts in the -NH and C=O peaks of xanthone and urea, as well as the disappearance of a -CN peak. Altered diffusion coefficients for both xanthone and urea were measured using DOSY-NMR, accompanied by notable improvements in solubility and dissolution profiles. The GM exhibited nearly a 2-fold increase in solubility, reaching 88.08 ± 1.25 µg/mL at 24 h and 90.97 ± 0.98 µg/mL at 72 h, alongside a 2-fold and 5-fold increase in dissolution at 0.21 µg/mL and 0.51 µg/mL for the physical mixture (PM) and GM, respectively. Furthermore, an enhanced antioxidant capacity was observed, as demonstrated in the calculated Trolox equivalent (TE) value, which increased from 1.48 ± 1.12 for xanthone alone to 1.65 ± 1.03 in the xanthone–urea complex. These findings confirm the successful complexation of xanthone and urea in a 1:1 molar ratio. Full article

Deep eutectic solvents (DESs) are environmentally friendly solvents formed by combining hydrogen bond donors and acceptors, resulting in a eutectic mixture with a lower melting point than the individual components. While there is extensive research on the electrochemical synthesis of platinum nanoparticles in DESs, to the best of our knowledge, there are no studies on the chemical reactivity of platinum(II) complexes in these systems. This study investigates the simple model reaction between K₂PtCl₄ and ethylenediamine (en), exploring the behaviour in DES environment, to optimize the synthesis of simple cisplatin-like platinum compounds with the potential objective of improving the traditional methods, decreasing the number of steps required for obtaining target compounds and reducing chemical waste. The reactions were performed in two hydrophilic DESs: choline chloride:glycerol 1:2 (glyceline, GL) and choline chloride:ethylene glycol 1:2 (ethaline, EG). The experiments, conducted in a 70% (v/v) DES and 30% 1:1 H₂O/D₂O mixture to allow for direct NMR analysis, revealed that en quickly formed [PtCl₂(en)], which further reacted to produce [Pt(en)₂]Cl₂. Reaction products were characterised by 1D (¹H and ¹⁹⁵Pt{¹H}) and 2D ([¹H,¹³C]-HSQC and [¹H,¹⁵N]-HSQC) NMR experiments. The discolouration of solutions, due to the consumption of K₂PtCl₄, and the precipitation of the purple Magnus salt [Pt(en)₂][PtCl₄] occurred over time. The main observed difference between the two solvent mixtures was the slower reactivity in glyceline, due to the much higher viscosity of the solution. Diffusion-ordered spectroscopy (DOSY) indicated lower water mobility in DES mixtures than pure water, with the reaction products closely associated with DES molecules. Full article

Covalent organic frameworks (COFs) hold promising potential as high-temperature proton conductors due to their highly ordered nanostructures and high specific surface areas. However, due to their limited functional groups and poor membrane-engineering properties, finding practical applications for COF-based proton-conducting materials still remains challenging. Herein, we proposed a universal strategy to fabricate proton-conducting composite membranes by the incorporation of sulfonic acid-bearing COFs and zwitterionic poly(ionic liquid)s (PILs) via in situ polymerization. Zwitterionic PILs with methanesulfonate counter ions can work as the intrinsic proton sources, and the sulfonic acid groups on the COF nanochannels can act as the extrinsic proton suppliers. Benefiting from the spatial nanoconfinement of long-range ordered nanochannels and the enhanced electrostatic interactions with PILs, the COFs with high densities of sulfonic acid groups can endow the as-prepared composite membrane (PIL@TpBD(SO₃H)₂) with a comparable anhydrous proton conductivity of 3.20 × 10⁻³ S cm⁻¹ at 90 °C, which is much higher than that of conventional Nafion (~10⁻⁵ S cm⁻¹ at 90 °C under anhydrous condition). ¹H NMR DOSY spectra reveal that both the diffusion and dissociation of protons can be drastically facilitated upon nanoconfinement, demonstrating the promising efficiency of nanochannels in proton conduction. Moreover, the obtained composite membranes possess outstanding mechanical and thermal stability, which is crucial for their practical application. This study demonstrates proton conduction elevation in nanoconfined PILs and provides a promising insight into the engineering of stable COF-based proton-conducting materials. Full article

Background/Objectives: Doxorubicin (Dox) is an anticancer drug used in the treatment of a wide range of solid tumors; however, Dox causes systemic toxicity and irreversible cardiotoxicity. The design of a new nanosystem that allows for the control of Dox loading and delivery results is a powerful tool to control Dox release only in cancer cells. For this reason, supramolecular self-assembly was performed between a poly(amidoamine) (PAMAM) dendrimer decorated with four β-cyclodextrin (βCD) units (PAMAM-βCD) and an adamantane–hydrazone–doxorubicin (Ad-h-Dox) prodrug. Methods: The formation of inclusion complexes (ICs) between the prodrug and all the βCD cavities present on the surface of the PAMAM-βCD dendrimer was followed by ¹H-NMR titration and corroborated by 2D NOESY experiments. A full characterization of the supramolecular assembly was performed in the solid state by thermal analysis (DSC/TGA) and scanning electron microscopy (SEM) and in solution by the DOSY NMR technique in D₂O. Furthermore, the Dox release profiles from the PAMAM-βCD/Ad-h-Dox assembly at different pH values was studied by comparing the efficiency against a native βCD/Ad-h-Dox IC. Additionally, in vitro cytotoxic activity assays were performed for the nanocarrier alone and the two supramolecular assemblies in different carcinogenic cell lines. Results: The PAMAM-βCD/Ad-h-Dox assembly was adequately characterized, and the cytotoxic activity results demonstrate that the nanocarrier alone and its hydrolysis product are innocuous compared to the PAMAM-βCD/Ad-h-Dox nanocarrier that showed cytotoxicity equivalent to free Dox in the tested cancer cell lines. The in vitro drug release assays for the PAMAM-βCD/Ad-h-Dox system showed an acidic pH-dependent behavior and a prolonged profile of up to more than 72 h. Conclusions: The design of PAMAM-βCD/Ad-h-Dox consists of a new controlled and prolonged Dox release system for potential use in cancer treatment. Full article

Background/Objectives: A range of NMR techniques, including diffusion ordered spectroscopy (DOSY) were used to characterise complex micelles formed by the anti-microbial cationic surfactant cetylpyridium chloride and to quantify the degree of interaction between cetylpyridium chloride and hydroxyethyl cellulose in a variety of commercially relevant formulations as a model for the disk retention assay. Methods: This NMR-derived binding information was then compared with the results of formulation analysis by traditional disk retention assay (DRA) and anti-microbial activity assays to assess the suitability of these NMR techniques for the rapid identification of formulation components that could augment or retard antimicrobial activity DRA. Results: NMR showed a strong ability to predict anti-microbial activity for a diverse range of formulations containing cetylpyridinium chloride (CPC). Conclusions: This demonstrates the value of this NMR-based approach as a rapid, relatively non-destructive method for screening commercial experimental anti-microbial formulations for efficacy and further helps to understand the interplay of excipients and active ingredients. Full article