CONH Groups Research Articles

Photochemical and Collision-Induced Cross-Linking of Asp, Glu, Asn, and Gln Residues in Peptide-Nitrile Imine Conjugate Ions in the Gas Phase.

Peptide conjugates furnished with a 2,5-diaryltetrazolecarbonyl tag at the C-terminal lysine, which we call peptide-tet-K, were found to undergo efficient cross-linking of Asp, Glu, Asn, and Gln residues to transient nitrile-imine intermediates produced by photodissociation and collision-induced dissociation (CID) of the tetrazole ring in gas-phase ions. UV photodissociation (UVPD) at 213 nm achieved cross-linking conversion yields of 37 and 61% for DAAAK-tet-K and EAAAK-tet-K, respectively. The yields for NAAAK-tet-K and QAAAK-tet-K were 29 and 57%, respectively. Even higher cross-link yields were found for CID-MS3 of stable denitrogenated ions, (peptide-tet-K-N2 + H)+, that were in the 69-83% range. Different types of cross-links were distinguished by CID-MSn that showed a distinct series of backbone fragment ions, loss of N-terminal groups, and loss of phenylhydrazine from the modified nitrile imines. The Asp and Glu side-chain carboxyl groups were major participants in cross-linking that resulted in proton and oxygen transfer to the nitrile imine group. Other types of cross-linking involved Asn and Gln CONH2 groups and backbone amides. Cyclic ion mobility-mass spectrometry was used to separate NAAAK-tet-K and QAAAK-tet-K conformers and products of their collision-induced denitrogenation. Linear nitrile-imine and cross-linked ion structures were identified by comparing the experimental collision cross sections (CCSexp) to those for structures obtained by combined Born-Oppenheimer molecular dynamics and density functional theory (DFT) calculations. The formation of cross-links was found to be energetically favorable and involved proton-facilitated nucleophilic attack at the nitrile-imine carbon atom.

Synthesis of polyhydroxyl-capped PAMAM dendrimer/silica composites for the adsorption of aqueous Hg(II) and Ag(I)

Water pollution caused by Hg(II) and Ag(I) poses deleterious effects to environmental safety. Adsorption is one of the promising methods to decontaminate aqueous metal ions. Herein, polyhydroxyl-capped poly(amidoamine) (PAMAM) dendrimer/silica composites (G1-OH and G2-OH) were prepared for decontaminating aqueous Hg(II) and Ag(I). The maximum adsorption capacity of G1-OH and G2-OH for Hg(II) are 0.45 and 0.76 mmol/g, while that for Ag(I) are 0.66 and 0.81 mmol/g. The optimum solution pH for the adsorption of Hg(II) and Ag(I) are both 6. The adsorption for Hg(II) and Ag(I) can reach equilibrium at 150 and 120 min, respectively. Pseudo-second-order model can be used to describe the adsorption kinetic process and the rate-controlling step is film diffusion process. Adsorption isotherm indicates the adsorption can be promoted by increasing concentration and temperature, and the adsorption process could be described by Langmuir model with chemical mechanism. G1-OH and G2-OH exhibit excellent adsorption selectivity and they can 100% adsorb Hg(II) or Ag(I) with the coexisting of Fe(III), Co(II), Cu(II) or Ni(II). Adsorption mechanism confirms C-N, OH and CONH groups play critical role for the adsorption of the two ions. The work may provide efficient adsorbents for the decontamination of aqueous Hg(II) and Ag(I) with practical value.

A molecular dynamics study for the extraction of cesium from aqueous solutions in the presence of functionalized carbon nanotube

ABSTRACT Molecular dynamics (MD) simulation was conducted to obtain the interfacial behavior of cesium (Cs+) extraction by functionalized carbon nanotubes (CNTs). The present study explores the extraction mechanism of Cs+ with functional groups such as OCH(CH3)2, and CONH2-based CNTs. The results display that adsorption capacity is improved significantly using a surface modification of a single-walled carbon nanotube (SWCNT) with isopropoxide and amide functional groups. The studies investigate the separation of Cs+ in the presence of functionalized CNTs from the ionic liquid (IL) – water biphasic systems. It has been found that CNT with OCH(CH3)2 functional group is highly efficient for Cs+ extraction as compared to the CONH2 group and bare CNT. The higher interaction energy between Cs+ and CNT with OCH(CH3)2 functional group (˗84.41 kcal/mol) was observed at the interface when compared with bare CNT (˗4.34 kcal/mol). In general, the order of Cs+ ion adsorption capacity on the CNT surface is CNT – OCH(CH3)2 > CNT – CONH2 > bare CNT. The current study offers quantitative data and insights into the extraction of metal ions with functionalized CNTs, which may be highly helpful for future technological exploration of the many nano-adsorbent-based investigations.

Konjac flour-mediated gut microbiota alleviates insulin resistance and improves placental angiogenesis of obese sows

Our previous study revealed that dietary konjac flour (KF) could remodel gut microbiota and improve reproductive performance of sows, but its underlying mechanisms remain unclear. This experiment aimed to investigate how dietary KF improves reproductive performance of obese sows. Here, 60 sows were assigned into three groups according to their backfat thickness: normal backfat sows fed with control diet (CON-N), high backfat sows fed with control diet (CON-H) and high backfat sows fed with KF inclusion diet (KF-H). The characteristics of sows and piglets were recorded. Next, fecal microbiota transplantation (FMT) was performed on female mice, followed by recording the characteristics of female mice. The results showed that compared with CON-H group, KF-H group showed downtrend in stillbirth rate (P = 0.07), an increase in placental efficiency (P < 0.01) and average piglet weight (P < 0.01); coupled with a decrease in the values of homeostasis model assessment-insulin resistance (P < 0.01); as well as an increase in placental vascular density and protein expression of angiogenesis markers (P < 0.01). As expected, sows fed KF diets had improved abundance and diversity of gut microbiota. More importantly, compared with CON-H(FMT) group, KF-H(FMT) group showed improvement in reproductive performance and insulin sensitivity (P < 0.05), as well as an increase in placental labyrinth zone and protein expression of angiogenesis markers (P < 0.05). Furthermore, we found a content increase (P < 0.05) of SCFAs in both KF-H group sow and KF-H (FMT) group mice. Overall, KF supplementation could alleviate insulin resistance, promote placental angiogenesis, and ultimately improve the reproductive performance of sows via gut microbiota remodeling.

Synthesis and Characterization of a Self-Crosslinked Organic Copolymer Kappa-Carrageenan/Polyacrylamide/Cetrimide (κ-CAR/PAAm/CI) Hydrogel with Antimicrobial and Anti-Inflammatory Activities for Wound Healing

The current study aimed to produce a material that has dual effects of healing and anti-inflammatory activity. For this purpose, a κ-carrageenan/polyacrylamide film loaded with cetrimide (κ-CAR/PAAm/CI) was developed using the manual casting technique. Definite concentrations of κ-CAR and AAm were heated at 80 °C for 2 h, and CI and glycerol were added. The solution was cast without using an initiator or crosslinker. The reaction of the sulfonic acid group -SO3H of κ-CAR with the –CONH2 group of PAAm lead to the formation of a sulfonamide (–SO2NH–) group. The characteristics of the produced films were investigated based on FT-IR, TGA, the contact angle, and mechanical properties. An improvement in the thermal stability of the κ-CAR/PAAm/CI2 film containing 1.5% CI was achieved, compared to the film with 0.5% CI (κ-CAR/PAAm/CI1). The contact angle measurement proved that the films were hydrophobic, enhanced by increasing the CI content. The tensile strength and elongation percent values are considered adequate for materials used in wound care. The κ-CAR/PAAm/CI2 (1.5% CI) film showed superior antimicrobial activity against P. aeruginosa, moderate activity against S. aureus, and low activity against E. coli. The κ-CAR/PAAm/CI2 film effectively inhibited heat-induced hemolysis and showed wound contraction activity at a level of 100% after 19 days of excision wound treatment. The prepared films may offer a promising approach for the development of effective wound dressings.

Thermochemistry of fusion, solution and hydrogen bonding in benzamide, N-methylbenzamide, and acetanilide

Aromatic amides are important precursors for biologically active compounds and are often considered model objects containing a NHCO group, which is ubiquitous in living organisms. In this work we experimentally studied the fusion and solution thermochemistry, and the crystal and liquid heat capacities of three amides: acetanilide, benzamide, and N-methylbenzamide. From the experimental and literature data obtained, the fusion enthalpies at 298.15 K were derived and their relationship with the solution enthalpies of the crystals in N,N-dimethylformamide was analyzed. From the analysis, the solution enthalpies of quasi-equilibrium liquid amides at 298.15 K and hydrogen bonding enthalpies in the neat liquid were derived. The solution enthalpies of quasi-equilibrium liquid amides at 298.15 K are useful for the further evaluation of the fusion enthalpies of benzamide and acetanilide derivatives at 298.15 K by solution calorimetry.

Sodium Salt of Partially Carboxymethylated Sodium Alginate-Graft-Poly(Acrylonitrile): II Superabsorbency, Salt Sensitivity and Swelling Kinetics of Hydrogel, H-Na-PCMSA-g-PAN.

The water absorption measurements of a novel superabsorbent anionic hydrogel, H-Na-PCMSA-g-PAN, has been reported first time in water with a poor conductivity, 0.15 M saline (NaCl, CaCl2, and AlCl3) solutions, and simulated urine (SU) solutions at various times. The hydrogel has been prepared by the saponification of the graft copolymer, Na-PCMSA-g-PAN (%G = 316.53, %GE = 99.31). Results indicated that as compared to the swelling capacity values evaluated in water with a poor conductivity, the ability of the hydrogel to swell in various saline solutions with the same concentration is significantly reduced at all different durations. The swelling tends to be Na+ > Ca2+ > Al3+ at the same saline concentration in the solution. Studies of the absorbency in various aqueous saline (NaCl) solutions also revealed that the swelling capacity decreased as the ionic strength of the swelling medium rose, which is consistent with the experimental results and Flory's equation. Furthermore, the experimental results strongly suggested that second-order kinetics governs the swelling process of the hydrogel in various swelling media. The swelling characteristics and equilibrium water contents for the hydrogel in various swelling media have also been researched. The hydrogel samples have been successfully characterized by FTIR to show the change in chemical environment to COO- and CONH2 groups after swelling in different swelling media. The samples have also been characterized by SEM technique.

Contribution Evaluation of Physical Hole Structure, Hydrogen Bond, and Electrostatic Attraction on Dye Adsorption through Individual Experiments

Disagreements over various unanswered questions about contribution of the adsorption process and functional groups on dye adsorption still exist. The main aim of this research was to evaluate the contributions of physical hole structure, hydrogen bond, and electrostatic attraction on dye adsorption. Three ideal representatives, namely, a sponge with porous structure, P(AM) containing -CONH2 groups, and P(AANa/AM) containing -COONa groups, were chosen to evaluate the above contributions. The methylene blue (MB) removal rates of these three products were compared through individual experiments. The results revealed that physical hole structure did not play a role in decreasing dye concentration. Hydrogen bond existed in dye adsorption but did not remarkably reduce dye concentration. The excellent removal results of P(AANa/AM) demonstrated that electrostatic attraction was critical in enriching dye contaminants from the solution into solid adsorbent. The results could provide insights into the dye adsorption mechanisms for further research.

Building Polymeric Framework Layer for Stable Solid Electrolyte Interphase on Natural Graphite Anode.

The overall electrochemical performance of natural graphite is intimately associated with the solid electrolyte interphase (SEI) layer developed on its surface. To suppress the interfacial electrolyte decomposition reactions and the high irreversible capacity loss relating to the SEI formation on a natural graphite (NG) surface, we propose a new design of the artificial SEI by the functional molecular cross-linking framework layer, which was synthesized by grafting acrylic acid (AA) and N,N'-methylenebisacrylamide (MBAA) via an in situ polymerization reaction. The functional polymeric framework constructs a robust covalent bonding onto the NG surface with -COOH and facilitates Li+ conduction owing to the effect of the -CONH group, contributing to forming an SEI layer of excellent stability, flexibility, and compactness. From all the benefits, the initial coulombic efficiency, rate performance, and cycling performance of the graphite anode are remarkably improved. In addition, the full cell using the LiNi0.5Co0.2Mn0.3O2 cathode against the modified NG anode exhibits much-prolonged cycle life with a capacity retention of 82.75% after 500 cycles, significantly higher than the cell using the pristine NG anode. The mechanisms relating to the artificial SEI growth on the graphite surface were analyzed. This strategy provides an efficient and feasible approach to the surface optimization for the NG anode in LIBs.

Physicochemical properties and prebiotic activities of polysaccharides from Zizyphus jujube based on different extraction techniques

Zizyphus jujube polysaccharide was extracted with hot water, ultrahigh pressure, deep eutectic solvent (DES) and ultrahigh pressure-assisted DES. Comparative analyses were conducted on the yield, physicochemical properties and prebiotic activity of four polysaccharides (JP-H, JP-U, JP-D and JP-UD). The yield of JP-UD (10.42 %) was 3.3 times that of JP-H (3.12 %), and its sugar content was the highest. JP-UD possessed the lowest Mw, while JP-H possessed the highest. Four JPs were acidic pyranose and mainly composed of galacturonic acid, arabinose and galactose. NMR results demonstrated that they contained not only similar glycosidic linkage but also the specific glycosidic linkage of →4)-α-D-Glcp-(l→ appeared in JP-U and JP-UD, the esterified units of GalA and CONH2 group appeared in JP-D and JP-UD, and the Terminal β-D-Galp and →4)-α-GalpA-(1→ appeared in JP-UD. JPs showed different proliferation effects on four lactobacillus strains, among which JP-UD exhibited the strongest prebiotic activity. Zizyphus jujube polysaccharides have great potential for application in the functional food and medical industry.

Double Lock Label Based on Thermosensitive Polymer Hydrogels for Information Camouflage and Multilevel Encryption.

Developing extra safety encryption technologies to prevent information leakage and combat fakes is in high demand but is challenging. Herein, we propose a "double lock" strategy based on both lower critical solution temperature (LCST) and upper critical solution temperature (UCST) polymer hydrogels for information camouflage and multilevel encryption. Two types of hydrogels were synthesized by the method of random copolymerization. The number of -CO-NH2 groups in the network structure of the hydrogels changed the enthalpic or entropic thermo-responsive hydrogels, and ultimately precisely controlled their phase transition temperature. The crosslink density of the polymer hydrogels governs the diffusion kinetics, resulting in a difference in the time for their color change. The combination of multiple LCST and UCST hydrogels in one label realized information encryption and dynamic information identification in the dimensions of both time and temperature. This work is highly interesting for the fields of information encryption, anti-counterfeiting, and smart responsive materials.

Mesoporous polystyrene-based microspheres with polar functional surface groups synthesized from double emulsion for selective isolation of acetoside

In this study, a series of the functionalized mesoporous polystyrene-based microspheres (FMPMs) with different functional comonomers (acrylamide, AM; ethyleneglycol dimethacrylate, EGDMA; hydroxyethyl methacrylate, HEMA) and ratios of styrene (St) to divinylbenzene (DVB) were designed and synthesized by a double emulsion interface polymerization method. Among them, St and DVB existed in the oil phase, forming the skeleton structure of FMPMs. AM, EGDMA or HEMA in the water phase formed functional layers on the inner and outer surfaces of FMPMs. The experimental results indicated that the optimal functional comonomers and the ratio of St to DVB were AM (provided the hydrophilic -CONH2 groups) and 1:1, respectively. Thus, A-FMPMs-2 exhibited the highest adsorption capacity of 108.95 ± 8.13 mg/g and the selectivity of 5.14 ± 0.17. These results were attributed to the hydrophilic -CONH2 groups on A-FMPMs-2, and these groups were beneficial to ACT molecules diffusion driven by concentration gradient, improving the adsorption performance. Furthermore, hydrophilic -CONH2 groups on the inner and outer surfaces of A-FMPMs-2 acted as hydrophilic sites that had a high-affinity interaction with ACT molecules, thus increasing the adsorption selectivity. In addition, A-FMPMs-2 had the highest specific surface area and largest pore volume, resulting in the highest adsorption capacity and adsorption selectivity. Therefore, the development of adsorbents with adjustable pore structure and a large number of hydrophilic sites will provide a new strategy for selective separation of bioactive components from natural products.

Synthesis and Physicochemical Characteristics of Chitosan Extracted from Pinna deltoides

Chitosan, a naturally produced polysaccharide that has a wide range of uses in biological, pharmacological, industrial, and commercial settings. The pen shell Pinna deltoides is a common species found along the coast of Thondi, and it is often collected as by-catch by fishermen. These species contain a high amount of chitin, which may be converted into chitosan. The goal of this research is to extract chitosan from P. deltoides and characterize it utilizing techniques like Fourier Transform Infrared Spectroscopy (FTIR), Micro Raman Spectroscopy, X-ray Powder Diffractometry (XRD), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). The existence of C-O-C glycosidic connection (1156 cm-1), NHCO group (1216 cm-1), aliphatic compound, -CH2 bend (1418 cm-1), and asymmetric CH2 stretching were verified by FTIR analysis (1204 cm-1). Chitosan extract exhibited a greater degree of deacetylation of 55.17%, which is consistent with prior studies. The highest peaks in the Micro Raman Spectra were 2937 cm-1, 1106 cm-1, and 1376 cm-1. The crystallinity of the chitosan at 2θ was anticipated using X-ray Powder Diffractometry (XRD) data at about 20°-25°. SEM micrograms verified the crystalline nature of the chitosan by revealing its soft and crystal-like arrangement of the chitosan. TGA was used to assess the sample's thermal constancy, and the chitosan's stability was found to be consistent with that of prior research.

Assessment of Hydrate Formation, Storage Capacity, and Transport Properties of Methane and Carbon Dioxide through Functionalized Carbon Nanotube Membranes

The present work investigates the gas hydrates, storage, and transport properties of methane (CH4) and carbon dioxide (CO2) across carbon nanotubes (CNTs) designed by CONH2 (aquaporin, AQP selective filter), H2O2, and COOH functional groups via molecular dynamics (MD) simulations. Two separate systems of water–CH4 and water–CO2 at different mole fractions have been considered. The main goal is to discuss, for the first time, the gas hydrate formation mechanism in the membrane technology framework as a promising approach to mitigate the drawbacks in traditional hydrate technologies. Our model membranes offer very high CH4 storage capacity concerning available experiments. The hydrate cages decrease since the mole fraction increases (or water loading decreases), suggesting a significant contribution of water hydrogen-bonded in the hydrate formation process. The CNT-CONH2 and CNT-H2O2 model membranes provide higher hydrate cage numbers compared to CNT-COOH, suggesting a better performance for CNT-CONH2. The CNT-CONH2 shows a higher hydrate cage in the presence of CO2, particularly at the small mole fraction, while CNT-COOH and CNT-H2O2 are good at the large mole fraction. Regardless of the gas type (CH4 or CO2), both CNT-CONH2 and CNT-H2O2 model membranes suggest better performance in gas hydrate formation. Moreover, our simulated model membranes indicate better efficiency in the formation of gas hydrates concerning available experiments. An enhancement in hydrate formation in the presence of CH4 was also found in the CNT-CONH2 and CNT-H2O2 model membranes concerning the bulk system, suggesting a better performance for CNT-CONH2. This finding could reflect the potential of the membrane-based hydrate formation over the bulk system. The transport properties of water/CH4/CO2 across the model membranes have also been discussed.

Tuning NO release of organelle-targeted furoxan derivatives and their cytotoxicity against lung cancer cells

We herein report a study on a set of hybrid compounds in which 3-R-substituted furoxan moieties (R = CH3, CONH2, CN, SO2C6H5), endowed with varying NO-releasing capacities, are joined to a mitochondrial probe, rhodamine B. Each product has been investigated for its ability to release NO both in physiological solution, in the presence of cysteine, and in A549 lung adenocarcinoma cancer cells. The cytotoxicity of all the products against the aforementioned cancer cells has been assessed, including the structurally related compounds with no mitochondrial targeting, which were taken as a reference. In the case of the models bearing the –CH3 and –CONH2 groups at the 3-position on the furoxan, only the targeted models showed a significant cytotoxic activity, and only at the highest concentrations, in accordance with their weak NO-releasing properties. On the contrary, the presence of the strong electron-withdrawing groups, as –CN and -SO2C6H5, at the 3-position gave rise to anticancer agents, likely because of the high NO-releasing and of their capability of inhibiting cellular proteins by covalent binding. In detail, the rhodamine hybrid containing the 3-SO2C6H5 substituted furoxan moiety emerged as the most interesting product as it showed high cytotoxicity over the entire concentration range tested. This substructure was also linked to a phenothiazine scaffold that is able to accumulate in lysosomes. Nevertheless, mitochondrial targeting for these NO-donor furoxan substructures was found to be the most efficient.

Investigation of gelation mechanism and the effects of APS on AlN slurries with Isobam

A novel and simple gelling system based on a water-soluble copolymer of isobutylene and maleic anhydride (commercial name, Isobam) was adopted to manufacture various ceramics via spontaneous gelation. The gelation mechanism of AlN slurry was investigated using infrared spectroscopy. Results show that Isobam was hydrolyzed to produce the –COOH group, and the hydrogen bonding was formed between the –COOH and –CONH2 groups of Isobam during spontaneous gelation. Meanwhile, the gelling process of the Isobam system could be accelerated via enhancing hydrogen bonding through APS addition. With 1 wt% addition of APS, the gelation time reduced to 23 h, the viscosity of 50 vol% AlN slurry decreased to 0.21 Pa·s, and the flexural strength of green body improved by 48%. Therefore, the presence of hydrogen bonding in the Isobam gelation mechanism was confirmed, and it could be enhanced by introducing APS to accelerate gelation.

A “turn-on” fluorescent probe based on BODIPY dyes for highly selective detection of fluoride ions

In the present paper, a novel difluoroboron dipyrromethene-based (BODIPY) fluorescent probe with a conjugated hydrazone group, named BDBH, was developed for the detection of F− with high selectivity and sensitivity. After addition of tetrabutylammonium fluoride (TBAF) into a BDBH solution, the fluorescence was “turned on”, which displayed an 80-fold increasement of emission intensity. The wavelengths of excitation and emission were 518 nm and 613 nm respectively, which were free from the background interference. The titration of 1H NMR (Nuclear Magnetic Resonance) indicated that the interaction involved hydrogen-bonding formation between the acidic H of –NH–CO group and F− at low concentration and deprotonation of N–H group at increasing concentration of fluoride. The theoretical calculations verified that once F− interacted with BDBH, the planarity and conjugation of BDBH enhanced, which resulted in a strong fluorescence emission at 613 nm. Furthermore, confocal fluorescence images of BDBH-incubated HeLa cells verified its potential application as an “off-on” sensor to monitor F− in living cells.

Isolation of natural caffeine from liptonâ„¢ black tea through acid-base liquid-liquid extraction approach, its medical significance and its characterization by thin layer chromatography and IR analysis

To isolate the caffeine from Liptonâ„¢ Black Tea Brand, a sequence of practices was applied. An Acid-Base Liquid-Liquid Extraction approach carried out to force the caffeine to be isolated in upper organic layer as extractant. By this method, first caffeine was isolated from tea bags through passing different steps of extraction, then caffeine was isolated from tea with the use of both Solid-Liquid approach as well as liquid-liquid extraction approach. A product of 0.05 g of pure caffeine was obtained giving the percentage yield or percent recovery of 1.22%. Calculated percent recovery was 1.2 %, this percentage yield clarified that in this tea brand, very small caffeine is investigated, this deduces a significant loss of product throughout the procedure which are due to formation of emulsions and not due to washing thoroughly with DCM to extract maximum yield. It is also significant to be considered that reactions of precursor with solvent pair may not be completed, so 100% yield is not conceivable. Due to much transfers in all processes, this loss might be occurred. Due to much transfers in all processes, this loss might be occurred that’s why repeated the process three times again. It is also revealed that as much water was added which decreased the concentration of Caffeine. On analysis with IR, Peak at f=3000Hz indicates the presence of -NH2 and -CONH2 groups while the peaks at f=1600 Hz and f=1750 Hz indicates the presence of alkene portion of the caffeine molecule which concluded that Caffeine is a purine base. Â

An investigation on percutaneous permeation of flurbiprofen enantiomers: The role of molecular interaction between drug and skin components

This work aimed to investigate skin permeation profiles of chiral flurbiprofen and clarify the molecular mechanism of transdermal permeation difference of enantiomers. The in vitro transdermal permeation of enantiomers through rat skin was studied by diffusion cells. Physicochemical parameters of model chiral drugs were determined. Molecular interaction between chiral flurbiprofen and ceramides of skin was investigated by FTIR, 13C NMR and molecular docking. The skin permeation mechanism of chiral drugs was characterized by ATR-FTIR, Raman spectra, DSC and molecular dynamic simulation. The results showed that the amount of the permeation and retention amount of (S)-flurbiprofen was 1.5 times over that of (R)-flurbiprofen. And it was proven that the difference was not induced by physicochemical properties but the molecular interaction between drug-skin components. (S)-flurbiprofen was easy to form stronger hydrogen bonding with –CONH group of skin lipids due to its steric configuration, which disturbed lipids arrangement more easily according to the results of ATR-FTIR (ΔνasCH2 = 1.00 cm−1), Raman spectra (ΔI2882/I2853 = 0.32) and the DSC (ΔTm stratum corneum = 11.75 °C). It was demonstrated more obvious effect on the second structure of keratin by ATR-FTIR study (Δ Amide I = 3.60 cm−1 and Δ Amide II = 3.38 cm−1). Better compatibility between (S)-flurbiprofen and lipids was confirmed quantificationally by thermodynamic analysis. In conclusion, the higher interaction between (S)-flurbiprofen and skin components, the higher skin permeation, which contributes to decrease the administration dose and increase the therapeutic effect.

Supramolecular organogel based on di-Fmoc functionalized unnatural amino acid: An attempt to develop a correlation between molecular structure and ambidextrous gelation

The supramolecular gels as soft material grasp more attention due to their increasing applications in diverse fields. Although numerous low molecular weight (LMW) gelators, which gelate either aqueous or organic solvents, have been developed in the past, the ambidextrous gelators (gelate both aqueous and organic solvents) are very limited. While many gelators have been discovered serendipitously, gelator’s rational design is still a challenge, especially ambidextrous gelators. In these two contexts, herein, we demonstrate the organogelation of a hydrogelator Nα, Nβ-di-fluorenylmethoxycarbonyl(Fm) functionalized L-2,3-diaminopropionic acid [G1] and thereby introduced a new ambidextrous gelator with an unnatural amino acid. Further, comparing with previous ambidextrous gelators, a correlation between molecular structure and ambidextrous gelation has been proposed to design new aromatic ambidextrous gelators. G1 found to gelates various commonly used organic solvents with a diverse polarity ranging from polar (methanol and ethanol) to non-polar (benzene and toluene) solvents. Interestingly, among the non-polar solvents, gelator G1 showed selectivity in gelating aromatic solvents as it cannot gelate acyclic and cyclic non-polar solvents. Organogels have been thoroughly characterized using various biophysical techniques. All the organogels show an entangled nanofibrillar morphology with ordered self-assembly of gelators, which are stabilized by aromatic π–π interactions of fluorenyl moieties and hydrogen bonding interactions between ‒CO‒NH‒ groups. The mechanical property (viscoelastic and thixotropic) of G1 organogels are comparable with reported supramolecular gels in polar and non-polar solvents, except toluene. The current findings, together with previous reports of fluorene and pyrene-based ambidextrous gelators, suggest that the amidation of LMW diamine compounds containing a polar group by two larger aromatic moieties could provide a chemical structure (dumb-bell arrangement)/self-assembling property to yield “ambidextrous” gelator. While the organogelation of G1 has been identified and characterized extensively, the present contemporary study, together with the previous observation, attempted to establish a correlation between molecular structure and ambidextrous gelation, leading to the design new LMW ambidextrous gelator by following a “dumb-bell” design.