Intermolecular Hydrogen-bonding Interactions Research Articles

Enhanced viability of probiotics encapsulated within synthetic/natural biopolymers by the addition of gum arabic via electrohydrodynamic processing

To enhance the probiotics’ viability, novel vehicles consisting of synthetic/natural biopolymers, i.e., polyvinyl alcohol (PVOH), polyvinylpyrrolidone, whey protein concentrate and maltodextrin, encapsulated with L. plantarum KLDS 1.0328 and gum arabic (GA) as a prebiotic were fabricated by electrohydrodynamic techniques. Inclusion of cells into composites caused an increase in conductivity and viscosity. Morphological analysis showed that cells were distributed along the electrospun nanofibres or distributed randomly in the electrosprayed microcapsules. Both intramolecular and intermolecular hydrogen bond interactions exist between biopolymers and cells. Thermal analysis revealed that the degradation temperatures (>300 °C) of various encapsulation systems have potential applications in heat-treatment foods. Additionally, cells especially immobilized in PVOH/GA electrospun nanofibres showed the highest viability compared with free cells after exposure to simulated gastrointestinal stress. Furthermore, cells retained their antimicrobial ability after rehydration of the composite matrices. Therefore, electrohydrodynamic techniques have great potential in encapsulating probiotics.

New supramolecular architectures of 4′-(4-quinolinyl)-2,2′:6′,2″-terpyridine based on tin complexes: Design, structural variations and thermal properties

The reactions of 4′-(4-quinolinyl)-2,2′:6′,2″-terpyridine (qtpy) with SnMe2Cl2 and SnMe2(NCS)2 have been investigated. The reaction of SnMe2Cl2 with qtpy resulted in the formation of the new complex [SnMe2Cl(qtpy)]+[SnMe2Cl3]− (1) while the reaction of SnMe2(NCS)2 with qtpy affords the complex [SnMe2(NCS)2(qtpy)] (2). The resulting products have been characterized using elemental analysis, IR and multinuclear NMR (1H, 13C, 119Sn) spectroscopy. The new complex [SnCl2(qtpy)] (3) was characterized by X-ray crystallography from an acetone/n-hexane solution of 1 which reveals that 1 dissociates in solution. The new complex 2[SnMe2(NCS)2(qtpy)]·CH2Cl2·H2O (2.CH2Cl2·H2O) was characterized by X-ray crystallography from a dichloromethane/n-hexane solution of 2. Interestingly, the crystal structure of 3 reveals that the Sn(II) center is penta-coordinated as a slightly distorted square pyramid, as suggested by the index of the trigonality (τ) parameter. However, Sn(IV) is hepta-coordinated in 2.CH2Cl2·H2O which adopts a pentagonal bipyramidal geometry. The intermolecular hydrogen bond interactions and π…π stacking interactions establish to form the supramolecular assembly. The Hirshfeld surfaces analysis confirms that H…H and π…π interactions play major roles to stabilize the crystal architectures. The crystal structure of 2.CH2Cl2·H2O reveals the formation of porous material containing voids which have been occupied by the solvents. The volume of voids is 370 and 17 Å3, occupied by dichloromethane and water, respectively. Analysis of Sn-N bond lengths of complex 2.CH2Cl2·H2O shows that Sn-N bond lengths are greater than 2.39 Å for active organotin(IV) complexes, suggesting it as a good candidate for anti‐tumor activity. The thermal properties of the complexes indicate that 1 is stable up to 120 °C while 2 decomposes at 147 °C.

A rhodanine derivative as a potential antibacterial and anticancer agent: Crystal structure, spectral characterization, DFT calculations, Hirshfeld surface analysis, in silico molecular docking and ADMET studies

A novel rhodanine derivative, namely 5-(4-dimethylaminobenzylidene) rhodanine “C12H12N2OS2”, was successfully crystallized from condensation route and characterized by NMR, FT-IR, UV–Vis spectral methods as well as single-crystal X-ray diffraction. This rhodanine derivate crystallizes in the monoclinic P21/c space group, with the cell parameters: a = 3.93590(10), b = 11.2480(3), c = 26.6703(7) Å and β = 93.8530(10)°. The molecular structure displays intra- (C − S···H) and intermolecular (N − H···O) hydrogen-bonding interactions. Micro-spectroscopy performed on single-crystals of the studied compound revealed the first absorption transition at 2.25 eV, and a well-structured luminescence peaked at 2.01 eV (0.15 eV broad). Density functional theory (DFT) calculations allowed the structure optimization, the electronic properties, the IR-vibrational modes and frequencies as well as the 1H and 13C NMR chemical shifts’ calculation. Furthermore, time-dependent DFT (TD-DFT) calculations were performed for the vertical transition energies. Hirshfeld surface analysis (HSA) showed the presence of non-conventional C–H···H–C, C–H···π and π···lp interactions and π−π stacking. The anti-cancer and anti-bacterial activities of the studied compound towards the Polo-like kinase PLK1 and the Escherichia coli MurB enzymes were in silico evaluated by performing molecular docking simulations. The results suggest that the molecule can significantly inhibit the enzymes’ active sites. Additionally, the physicochemical and pharmacokinetic characteristics of the molecule were evaluated through absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis, and the results ensure its good drug-likeness properties.

A turn-on fluorescent Zn(II) metal-organic framework sensor for quantitative anthrax biomarker detection.

2,6-Pyridine dicarboxylic acid (DPA) is considered one of the main anthrax biomarkers, and the detection of DPA is of great significance. This work presents a Zn(II)-based metal-organic framework (MOF) with the formula {[Zn2(2,6-NBC)2(vlpy)Zn(2,6-NBC)(vlpy)0.5]·0.8(2,6-H2NBC)·H2O}n (1) assembled from 2,6-naphthalenedicarboxylic acid (2,6-H2NBC) and 4,4'-vinylenedipyridine (vlpy) for a photoluminescence sensor matrix for DPA detection. 1 features a 3D pillar-layer framework with nanopore sizes of ca.13.165 Å × 12.731 Å, 12.725 Å × 11.018 Å and 13.114 Å × 13.165 Å along the three directions, occupied by lattice water and disordered 2,6-H2NBC molecules. The obtained 1 can be used as a turn-on fluorescence sensor for the detection of DPA with high selectivity, excellent sensitivity and recyclability. The luminescence of 1 demonstrates an obvious color change from blue to purplish blue as the DPA concentration rises. Furthermore, a linear correlation is presented between the fluorescence and a low DPA concentration of 0-0.3 mM, and the detection limit can reach as low as 128 nM, much lower than that of an infectious dose to a human of anthrax spores (60 μM). A fluorescence test paper is fabricated to detect DPA rapidly through color change. DFT calculations indicate the intermolecular photoinduced electron-transfer transition and hydrogen-bonding interaction between DPA molecules and the skeleton of 1 induces the "turn-on" fluorescence sensing of DPA behavior.

An organic superconductor, (TEA)(HEDO-TTF-dc)2·2(H2C2O4), coupled with strong hydrogen-bonding interactions.

A new organic superconductor (TEA)(HEDO-TTF-dc)2·2(H2C2O4) (H2EDO-TTF-dc = ethylenedioxy-tetrathiafulvalene dicarboxylic acids) with an onset TC of 4.0 K, was successfully obtained using oxalic acid and HEDO-TTF-dc anion donor. The crystal structure analysis indicated that strong π-π overlaps and very strong intra- and inter-molecular hydrogen-bonding interactions exist between the HEDO-TTF-dc anion donors and oxalic acid molecules.

Development of active packaging with chitosan, guar gum and watermelon rind extract: Characterization, application and performance improvement mechanism

The objective of this study was to make a film matrix containing chitosan (CS) and guar gum (GG), and to improve the physicochemical properties of the film using watermelon rind extract (WRE) as a cross-linker and active substance for the preservation of fresh-cut bananas. The results of Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy showed that the WRE and CG matrix formed intermolecular hydrogen bond interactions, which made the structure of the resulting films more compact. With increasing amounts of WRE, the mechanical properties of the films were significantly increased, but the permeability of water vapor and oxygen was significantly decreased (p < 0.05). Notably, when the amount of extract reached 4 wt%, the DPPH radical scavenging activity of the composite film significantly increased to 83.24 %, and the antibacterial activity also reached its highest value. Fresh-cut bananas were stored at room temperature with polyethylene film, CG and CG-WRE. The CG with 4 wt% WRE effectively inhibited the changes in appearance, firmness, weight, color and total soluble solids content of fresh-cut bananas during storage. Therefore, CG-WRE as a novel active food packaging material, has good physicochemical properties and great potential to extend the shelf life of foods.

Ultrasonic assistant synthesis, structure and magnetic property of a 3D supermolecular framework based on 2-isobutyl-1H-imidazoledicarboxylate and copper(II) ions

• The 3D supermolecular frameworks is constructed by 2D layer structure [Cu(H 2 IDC) 2 ]n through the intermolecular hydrogen bond interactions and self-substituting group support of the isobutyl. • Thermogravimetric stability and temperature dependence phase transfer process (crystal → amorphous phase → crystal phase → CuO) have been discussed in detail. • Antiferromagnetic behaviors between the Cu(II) ions have been investigated. A 3D supermolecular framework copper(II)-2-isobutyl-1H-imidazoledicarboxylate, namely [Cu(H 2 IDC) 2 ]n (H 3 IDC = 2-isobutyl-1H-imidazoledicarboxylate), has been successfully synthesized under hydrothermal condition assisted by ultrasonic stir. In the structure, each bridging H 2 IDC - ligand connects two copper(II) octahedral CuO 4 N 2 to form a 2D layer structure [Cu(H 2 IDC) 2 ]n, then the adjacent layers are further connected via the intermolecular hydrogen bond interactions and the support from the substituent group of isobutyl to form a 3D supermolecular framework. The synthetic conditions, thermogravimetric stability and temperature dependence phase transfer process have been discussed. Additionally, the magnetic property study indicates that there are antiferromagnetic interactions in the structure.

Theoretical study of excited state intramolecular proton transfer behavior for 2-phenyl,3- hydroxybenzo[g]quinolones and its derivative in the aprotic and protic solvents

We mainly focus on exploring the excited state intramolecular proton transfer (ESIPT) and fluorescence behavior of 2-phenyl,3-hydroxybenzo[g]quinolones (2P3HBQ) and its derivative (2HP3HBQ) in aprotic and protic solvents. The time-dependent density functional theory calculation results show that 2HP3HBQ is more prone to ESIPT process than 2HP3HBQ, whether in aprotic or protic solvents. In addition, 2P3HBQ and 2HP3HBQ are more prone to ESIPT process in protic solvents, proving that intermolecular hydrogen bond interaction can promote ESIPT process. Meanwhile, the intermolecular hydrogen bond interaction will also cause the blue-shift of the emission spectrum for 2P3HBQ and 2HP3HBQ.

Synthesis and Computational and X-ray Structure of 2, 3, 5-Triphenyl Tetrazolium, 5-Ethyl-5-phenylbarbituric Acid Salt

The title compound triphenyl tetrazolium (TPT) of phenobarbital, 5-Ethyl-5-phenylbarbituric acid triphenyl tetrazolium salt (4) was prepared by the reaction of 5-Ethyl-5-phenyl-2,4,6(1H, 3H, 5H)-pyrimidinetrione, monosodium salt (1) with triphenyl tetrazolium chloride (3) in deionized water at an ambient temperature through a cation exchange reaction. Colorless crystals of compound four suitable for an X-ray structural analysis were obtained by slow evaporation from acetonitrile. Compound four had crystallized in the monoclinic space group, P21/c, with a = 15.3678 (9) Å, b = 12.2710 (7) Å, c = 21.8514 (13) Å, β = 109.867 (2)°, V = 3875.5 (4) Å3, and Z = 4. A Through density functional theory (DFT) calculations, the probable molecular association structure in the phenobarbitone -triphenyl tetrazolium solution was studied. With the 6-311G-(d,p) basis set, the gas phase features of the phenobarbital-triphenyl tetrazolium clusters with a phenobarbitone dimer and water molecules, including an optimum structure and intermolecular hydrogen bonding, were investigated in detail. In addition, the positions and strengths of the intermolecular hydrogen bond interactions between the phenobarbitone and triphenyl tetrazolium molecules were analyzed using atoms in molecule (AIM) analysis, reduced density gradient (RDG) methods, the XRD method, and the non-covalent interaction (NCI) index method. In addition, the molecular electrostatic potential (MEP) surfaces were analyzed to determine the electrophilic and nucleophilic centers.

A green, effective, and synergistic flame retardant for poly(ethylene-co-vinyl acetate) resin

It is a challenge to prepare flame-retardant composites via addition of low content of fire retardant all the time. In this contribution, a compounding method based on combining long-chain phosphaphenanthrene (DPP) flame retardant and two dimensional (2D) black phosphorene (BP) is used to achieve molecule-scale dispersion of a Si-P flame retardant in poly(ethylene-co-vinyl acetate) (EVA) matrix (donated as EVA/DBP) by the interaction of intermolecular hydrogen bonds. By this way of doing, EVA/DBP composites with various flame retardant contents were investigated. Cone calorimeter, vertical combustion, thermo-gravimetric analysis, scanning electron microscope, Raman Spectrum, and Fourier transform infrared spectroscopy are used to evaluate the flame retardance and analyze the corresponding mechanisms. The results show that the DBP can effectively improve the flame retardant properties and thermal stability of EVA with slight influence on its mechanical performance. Compared with pure EVA resin, EVA/DBP composite with 5 wt% dosage of DBP achieves UL94-V0 rating, 9.6% increased in limiting oxygen index (LOI), 16.1% and 47.5% reduction in total heat release (THR) and peak heat release rate (PHRR), respectively. Moreover, the tensile yield stress and elongation at break are only reduced by 8.1% and 6.2%, respectively. It shows that the interaction between DBP and EVA effectively promote gas phase fire resistance.

Synthesis, crystal structure and Hirshfeld surface analysis of catena-poly[[bis-(semicarbazide-κ2 N,O)copper(II)]-μ-sulfato-κ2 O:O'

The title polymer, [Cu(SO4)(CH5N3O)2] n , has been synthesized from aqueous solutions of CuSO4 and semicarbazide. In the crystal structure, the CuII atoms are chelated by two neutral semicarbazide mol-ecules through the oxygen atom and a nitro-gen atom of the amino group. The remaining two positions of the Jahn-Teller-distorted octa-hedral coordination sphere are occupied by oxygen atoms of two sulfate anions in the axial positions. The coordination bonds of the latter associate the polyhedra into polymeric chains running parallel to the c axis. There is a weak intra-molecular hydrogen bond between the N-H group and an oxygen atom of the SO4 2- anion. Thirteen relatively weak inter-molecular hydrogen-bonding inter-actions link the chains into a three-dimensional network. Hirshfeld surface analysis revealed that 64.7% of the inter-molecular inter-actions are from O⋯H/H⋯O contacts and 20.1% from H⋯H contacts. Other inter-actions such as N⋯H/H⋯N or C⋯H/H⋯C contribute less to the crystal packing.

Selective Formation of Unsymmetric Multidentate Azine-Based Ligands in Nickel(II) Complexes.

A mixture of 2-pyridine carboxaldehyde, 4-formylimidazole (or 2-methyl-4-formylimidazole), and NiCl2·6H2O in a molar ratio of 2:2:1 was reacted with two equivalents of hydrazine monohydrate in methanol, followed by the addition of aqueous NH4PF6 solution, afforded a NiII complex with two unsymmetric azine-based ligands, [Ni(HLH)2](PF6)2 (1) or [Ni(HLMe)2](PF6)2 (2), in a high yield, where HLH denotes 2-pyridylmethylidenehydrazono-(4-imidazolyl)methane and HLMe is its 2-methyl-4-imidazolyl derivative. The spectroscopic measurements and elemental analysis confirmed the phase purity of the bulk products, and the single-crystal X-ray analysis revealed the molecular and crystal structures of the NiII complexes bearing an unsymmetric HLH or HLMe azines in a tridentate κ3 N, N’, N” coordination mode. The HLH complex with a methanol solvent, 1·MeOH, crystallizes in the orthorhombic non-centrosymmetric space group P212121 with Z = 4, affording conglomerate crystals, while the HLMe complex, 2·H2O·Et2O, crystallizes in the monoclinic and centrosymmetric space group P21/n with Z = 4. In the crystal of 2·H2O·Et2O, there is intermolecular hydrogen-bonding interaction between the imidazole N–H and the neighboring uncoordinated azine-N atom, forming a one-dimensional polymeric structure, but there is no obvious magnetic interaction among the intra- and interchain paramagnetic NiII ions.

Growth, Quantum Chemical Computations, NLO and Spectroscopic Studies of 2-Amino 5-Chloro Pyridine Single Crystal in Comparison with Certain Aminopyridine Derivatives.

Single crystals of an organic 2-amino 5-chloropyridine (2A5CP) have been grown by slow evaporation and confirmed by XRD. DFT calculations, spectroscopic studies, Photoluminescence, and thermal analysis were performed to characterize the crystal. The third-order nonlinearity was measured using the open and closed aperture Z-scan techniques. The most stable molecular structure is optimized by DFT/CAM-B3LYP method with 6-311++G(d,p) basis set in the Gaussian 09 program package. Optimized geometry, AIM analysis, MEP, and Mulliken Population analysis prove the presence of intermolecular N-H…N hydrogen bonds in the dimer. Natural Bond Orbital analysis predicts that the chlorine and NH2 substitutions induce hyperconjugation with σ bonds in the C-C double bond and strong π conjugation in the pyridine ring. The π*→ π* conjugative intramolecular charge-transfer interactions in 2A5CP have stabilization energy ∼ 984 kJ/mol which leads to enhancing optical properties. Experimental NMR, FTIR and FT-Raman spectra of 2A5CP have been recorded and compared with theoretical spectra. The vibrational wavenumbers are simulated (scaled) and assigned based on potential energy distribution. Hirshfeld surface analysis represented in a 2D fingerprint plot displays the percentage contribution of interactions between atoms. The optical bandgap of the grown crystal has been calculated as 3.54 eV. In the present investigation, the percentage contribution of interactions, intermolecular hydrogen-bonded interactions, charge on N and H atoms, HOMO-LUMO energy gap, electronic transitions, first-order hyperpolarizability, and two-photon absorption coefficient (β) of 2A5CP were compared with those of certain aminopyridine derivatives. The results of our investigation predict that the 2A5CP is a stable complex below 147 °C with third-order nonlinearity that can be used as a new green-light emitting organic material with potential application as an efficient optical limiter in optoelectronics.

Molecular platform based on a spiroindolinonaphthopyran of the diphenyloxazole series for the creation of polychromogenic molecular systems

A spiroindolinonaphthopyran of the diphenyloxazole series along with photochromism possesses a number of chromogenic properties such as solvatochromism, ionochromism, solid state phasochromism and fluorescence. The nature of these effects is associated both with the possibility of the spiropyran existence under its two forms (cyclic and merocyanine) and with the peculiarities of the molecular structure, in particular, with the presence of a diphenyloxazole fragment. Photochromic properties of the spiroindolinonaphthopyran do not exhibit a drastic dependence on the nature of solvents, including those that are capable of specific intermolecular hydrogen bond interactions. In addition, good resistance to photodegradation in the mode of photochromic balance opens up possibilities for designing polychromogenic molecular systems based on them. The positive solvatochromism of the first type, which is noticeably manifested in the case of merocyanine isomers, allowed establishing the weak polarity of their ground state. Solvatochromism of the second type demonstrates a significant spectral contrast (up to 227 nm) due to the existence of an equilibrium of cyclic and merocyanine isomers. The intensity of the effect increases upon passing from toluene to DMSO due to the shift of the equilibrium towards the merocyanine isomers. The presence of a chelate center formed by the merocyanine oxygen atom and the nitrogen atom of the diphenyloxazole fragment allows observing ionochromic transformations of the spiropyran molecule associated with the formation of coloured complex compounds upon its interaction with Co, Cu, Ni, Zn, Cd, Mn ions. It has been established that solutions of Zn, Cd, and Mn complexes exhibit the negative photochromism properties. The change in the solid state of spirpyran is accompanied by a change in the ability to undergo photochromic transformations. Under standard conditions the spiropyran exhibits photochromic properties in the crystalline state, but not in the amorphous one. The combination of chromogenic properties makes it possible to implement fluorescent molecular switches, bipolar absorption switches, photodynamic chemosensors, and solid-state phase transitions control the chromogenic properties based on spiropyrans of diphenyloxazole series. The possibility of structural modification leading to an enhancement of some properties and/or a weakening of other ones makes it possible to consider a spiroindolinonaphthopyran of a diphenyloxazole series as a molecular platform for creating polychromogenic molecular systems with desired properties.

Synthesis of Superhydrophobic/Superoleophilic stearic acid and Polymer-modified magnetic polyurethane for Oil-Water Separation: Effect of polymeric nature

The superhydrophobic/superoleophilic materials based on polyurethane foams have been layered with three different polymers and extensive modification with iron/magnetic nanocomposite. The general desires are to study the effect of the polymer layer and to eliminate the oil contaminant from the oil–water system which is crucial due to the development of environmental technologies. These materials were generated by facile dip-coating two-step method on the polyurethane foams (PUF) surface. PUF was directly layered with polydopamine/polypyrrole/polyaniline (PDA/PPy/PANI) and incorporated with Fe-SA (stearic acid) nanocomposites by ultrasonication and refluxing. In addition, characterization by FTIR, SEM/EDX, XRD, and TGA presented that the polymer layer and Fe-SA nanocomposites successfully covered the PUF surface caused by the chelating interaction between the carboxylates and active sites on iron particles due to intermolecular hydrogen bond interaction. Interestingly, the water contact angle (WCA) measurement of the nanocomposites displayed that the contact angle significantly improved up to 164°. After 20 cycles of oil absorption capacity, the WCA steadily remained up to 153° indicating powerful superhydrophobic properties of the materials. Furthermore, the oil absorption capacity of the materials was evaluated using typical oil–water separation methods such as reusability, separation efficiency, and oil permeate flux. The results exhibited that the modified PUFs have enhanced the absorption capacity up to 44 times the foam weight, 99 % separation efficiency, and about 8000 L.m−2.h−1 oil flux. For oil removal, the dyed oil phase was rapidly absorbed within 2 s confirming the highly used products for a wide area of oil–water separation. PDA-coated PUF nanocomposites obtained the most outstanding results due to their remarkable interfacial adhesion properties which provide larger active functional groups for hydrogen bonding interaction on PUF surface and Fe-SA nanocomposites.

Excess Thermodynamic Properties of Binary Mixtures of Dimethyl Malonate with some Branched Alkanols

The intermolecular hydrogen bond interactions in the dimethyl malonate with some branched alkanols (2-methyl-1-propanol, 2-propanol, and 2-butanol) binary mixture have been studied experimentally and theoretically. The ultrasonic velocities U, densities ρ of binary mixtures of dimethyl malonate with 2-methyl-1-propanol, 2-propanol, 2-butanol from 303.15 K to 318.15 K were measured. Excess molar volume (VE), deviation in adiabatic compressibility (Δβad) and excess intermolecular free length ( LEf) have been calculated from the measured experimental data. It is observed that the order of interactions in dimethyl malonate – branched alkanols mixtures is 2-methyl-1-propanol &gt; 2-propanol &gt; 2-butanol.

An investigation of a relatively rigid acyclic salamo-type ligand and its square planar Cu(II) complex

A relatively rigid acyclic salamo-type ligand H2L and its square planar Cu(II) complex, [Cu(L)]·CH3OH, were synthesized and characterized by X-ray crystallography, as well as Fourier-transform infrared spectra, UV–Vis spectra, Hirshfeld surface analyses and DFT calculations. The ligand crystallizes in monoclinic space group P 21/c and has pairs of intramolecular hydrogen bonds between the oxime nitrogen atoms and the hydroxyl groups. The Cu(II) complex crystallizes in the monoclinic space group P 21/c. The Cu(II) ion is located in the N2O2 cavity of the fully deprotonated salamo-type ligand (L)2− unit, thus forming a four-coordinate distorted square planar geometry. At the same time, a belt-like, 2-D supramolecular structure is formed by the interaction of intermolecular hydrogen bonds, and the intermolecular interaction force is quantitatively analyzed by Hirshfeld surfaces. Significantly, fluorescence properties of the ligand and its Cu(II) complex were also studied. The coordination ratio of the Cu(II) complex was proved by UV–Vis and fluorescence titration experiments.

Cosmetic-Derived Mannosylerythritol Lipid-B-Phospholipid Nanoliposome: An Acid-Stabilized Carrier for Efficient Gastromucosal Delivery of Amoxicillin for In Vivo Treatment of Helicobacter pylori.

Helicobacter pylori infection is a leading cause of gastritis and peptic ulcer. Current treatments for H. pylori are limited by the increase in antibiotic-resistant strains and low drug delivery to the infection site, indicating the need for effective delivery systems of antibiotics. Although liposomes are the most successful drug delivery carriers that have already been applied commercially, their acidic stability still stands as a problem. Herein, we developed a novel nanoliposome using cosmetic raw materials of mannosylerythritol lipid-B (MEL-B), soy bean lecithin, and cholesterol, namely, LipoSC-MELB. LipoSC-MELB exhibited enhanced stability under the simulated gastric-acid condition, owing to its strong intermolecular hydrogen-bond interactions caused by the incorporation of MEL-B. Moreover, amoxicillin-loaded LipoSC-MELB (LipoSC-MELB/AMX) had a particle size of approximately 100 nm and exhibited sustained drug release under varying pH conditions (pH 3–7). Besides, LipoSC-MELB/AMX exhibited significantly higher anti-H. pylori and anti-H. pylori biofilm activity as compared with free AMX. Furthermore, LipoSC-MELB was able to carry AMX across the barriers of gastric mucus and H. pylori biofilms. Remarkably, in vivo assays indicated that LipoSC-MELB/AMX was effective in treating H. pylori infection and its associated gastritis and gastric ulcers. Overall, the findings of this study showed that LipoSC-MELB was effective for gastromucosal delivery of amoxicillin to improve its bioavailability for the treatment of H. pylori infection.

Three-dimensional tailor-made collagen-like proteins hydrogel for tissue engineering applications.

Despite the potential tunable properties of blank slate collagen-like proteins (CLP), an alternative to animal-originated collagen, assembling them into a stable 3D hydrogel to mimic extracellular matrix is a challenge. To address this constraint, the CLP (without hydroxyproline, CLPpro) and its variants encoding functional unnatural amino acids such as hydroxyproline (CLPhyp) and 3,4-dihydroxyphenylalanine (CLPdopa) were generated through genetic code engineering for 3D hydrogel development. The CLPhyp and CLPdopa were chosen to enhance the intermolecular hydrogen bond interaction through additional hydroxyl moiety and thereby facilitate the self-assembly into a fibrillar network of the hydrogel. Hydrogelation was induced through genipin as a cross-linker, enabling intermolecular cross-linking to form a hydrogel. Spectroscopic and rheological analyses confirmed that CLPpro and its variants maintained native triple-helical structure, which is necessary for its function, and viscoelastic nature of the hydrogels, respectively. Unlike CLPpro, the varients (CLPhyp and CLPdopa) increased pore size formation in the hydrogel scaffold, facilitating 3T3 fibroblast cell interactions. DSC analysis indicated that the stability of the hydrogels got increased upon the genetic incorporation of hydroxyproline (CLPhyp) and dopa (CLPdopa) in CLPpro. In addition, CLPdopa hydrogel was found to be relatively stable against collagenase enzyme compared to CLPpro and CLPhyp. It is the first report on 3D biocompatible hydrogel preparation by tailoring CLP sequence with non-natural amino acids. These next-generation tunable CLP hydrogels open a new venue to design synthetic protein-based biocompatible 3D biomaterials for tissue engineering applications.

Molecular dynamics and docking studies on potentially active natural phytochemicals for targeting SARS-CoV-2 main protease

In the present study, we screened eighty seven novel phytochemical compounds from four popular herbs, such as, Aegle Marmelos, Coleus Amboinicus, Aerva Lanata and Biophytum Sensitivum and identified the best three for targeting the main protease (Mpro) receptor of SARS-CoV-2. After categorizing all the phytochemicals based upon LibDock scores and hydrogen bonding interactions, the top ranked 26 compounds were further subjected for detailed Molecular dynamics (MD) study. From these screening we identified that Aegelinosides B leads the list with a high LibDock value of 142.50 (binding energy: −8.54 kcal/mol), which is better than several popular reference compounds namely, Tipranavir (LibDock score, 141.50), Saquinavir (125.34), Zopicole (122.9), Pirenepine (122.70), (115.37), Metixene (109.18), Oxiconazole Pimozide (138.00) and Rimonabant (91.88). Detailed analysis for structural stability (RMSD), Cα fluctuations (RMSF), intermolecular hydrogen bond interactions, effect of solvent accessibility (SASA) and compactness (Rg) factors were performed for the best six compounds and it is found that they are very stable and exhibit folding behavior. Apart from the docking and MD tests, through further drug-likeness and toxicity tests, three compounds, such as, Aegelinosides B, Epicatechin, and Feruloyltyramine (LibDock scores, respectively, 142.50, 124.33 and 129.06) can be suggested for fighting SARS-CoV-2. Communicated by Ramaswamy H. Sarma