Effect Of Molecular Structure Research Articles

Injectable Hyaluronic Acid-Based Hydrogels for Rapid Endoscopic Submucosal Dissection.

Endoscopic submucosal dissection (ESD) is a widely used procedure for the treatment of early and precancerous gastrointestinal lesions and has become the standard treatment. In this procedure, the commonly used materials have a short retention time and a limited lifting capacity, which will prolong the duration of the ESD procedure. Furthermore, these liquids tend to diffuse after ESD surgery, failing to adequately protect the wound. Therefore, we designed and developed injectable hydrogels based on hyaluronic acid. A series of oxidized hyaluronic acid (OHA) and hydrazide hyaluronic acid (AHA) were synthesized, and 16 kinds of injectable hydrogels were fabricated to investigate the effects of molecular structures on the properties of the hydrogels. Among these, the O1A3 hydrogel exhibited a suitable injection performance, gelation time, and mechanical properties, along with good blood and cell compatibility in vitro. Subsequently, in a porcine model of the ESD procedure, the results demonstrated that the O1A3 hydrogel exhibited a good retention time and lifting performance while also significantly reducing the operation time from 1-2 h to ∼10 min. Furthermore, the adhesive property of the O1A3 hydrogel on small bleeding spots and wounds could be observed, which was beneficial in protecting the wound from the complex environment of the gastrointestinal tract. The present work of injectable hyaluronic acid-based hydrogels could be promising to improve the efficiency of ESD surgery.

Long-Range Charge Transport in Molecular Wires.

Long-range charge transport (LRCT) in molecular wires is crucial for the advancement of molecular electronics but remains insufficiently understood due to complex transport mechanisms and their dependencies on molecular structure. While short-range charge transport is typically dominated by off-resonant tunneling, which decays exponentially with molecular length, recent studies have highlighted certain molecular structures that facilitate LRCT with minimal attenuation over several nanometers. This Perspective reviews the latest progress in understanding LRCT, focusing on chemical designs and mechanisms that enable this phenomenon. Key strategies include π-conjugation, redox-active centers, and stabilization of radical intermediates, which support LRCT through mechanisms such as coherent resonant tunneling or incoherent hopping. We discuss how the effects of molecular structure, length, and temperature influence charge transport, and highlight emerging techniques like the Seebeck effect for distinguishing between transport mechanisms. By clarifying the principles behind LRCT and outlining future challenges, this work aims to guide the design of molecular systems capable of sustaining efficient long-distance charge transport, thereby paving the way for practical applications in molecular electronics and beyond.

Thermoanalytical studies on cross-linked polyurethane networks: effect of polyol molecular weight and structure of cyclodextrins

Thermoanalytical studies on cross-linked polyurethane networks: effect of polyol molecular weight and structure of cyclodextrins

The Effect of Molecular Structure on the Properties of Fluorene Derivatives for OLED Applications.

A new family of symmetrical fluorene derivatives with different types of substituents attached to the C-2 and C-7 positions of the fluorene core synthesized by the Sonogashira coupling reactions is reported. The electronic structures and the properties of the compounds investigated by means of photoelectron emission spectroscopy, UV-Vis absorption and photoluminescent spectroscopy as well as by DFT and TD-DFT theoretical calculations are discussed. It is shown that the nature of substituents influences the π-conjugation of the molecules. No intermolecular charge transfer within the investigated wavelength range is observed. The applicability of the synthesized compounds in organic light-emitting diodes (OLEDs) based on exciplex emission is demonstrated. The advanced co-deposition technique with the tuned OLED architecture was applied and resulted in improved OLED parameters.

Multi-scale structural and In vitro digestion properties of amino acids-tiger nut starch complexes and applications in noodles

Protein and its hydrolysates play crucial roles as nutritional components in daily diets and additives in food processing, their effect on starch digestion attracted extensive attention. In this study, tiger nut starch (TNS) mixed with multiple type of amino acids were subjected to annealing (ANN) treatment. Through the analysis of morphological characteristics, physicochemical properties, molecular structure, and enzyme inhibition effects of these amino acids, the mechanism of diverse in vitro digestion properties of the resulting mixtures were examined. Our findings revealed that the addition of phenylalanine (Phe), lysine (Lys), and histidine (His) significantly reduced rapidly digestible starch (RDS) content while increasing levels of slowly digestible starch (SDS) and resistant starch (RS) content (p<0.05). Phe, Lys, and His were found to influence digestion properties through molecular interactions, as indicated by analyses of relative crystallinity (RC) and short-range order. Notably, Lys and His exhibited notable amylase inhibition effects consequently enhanced enzyme resistance, particularly His on α-amylase (11.98%) and Lys on α-glucosidase (89.33%). Finally, wheat noodles prepared with TNS-Lys and TNS-His showed favorable processing properties and digestion resistant, highlighting their promising applications in low glycemic index foods.

Effect of molecular structure on membrane diffusion: Triphenylmethanes across Escherichia coli studied by second harmonic light scattering

Understanding how the structure of molecules affects their permeability across cell membranes is crucial for many topics in biomedical research, including the development of drugs. In this work, we examine the transport rates of structurally similar triphenylmethane dyes, malachite green (MG) and brilliant green (BG), across the membranes of living Escherichia coli (E. coli) cells and biomimetic liposomes. Using the time-resolved second harmonic light scattering technique, we found that BG passively diffuses across the E. coli cytoplasmic membrane (CM) 3.8 times faster than MG. In addition, BG exhibits a diffusion rate 3.1 times higher than MG across the membranes of liposomes made from E. coli polar lipid extracts. Measurements on these two molecules, alongside previously studied crystal violet (CV), another triphenylmethane molecule, are compared against the set of propensity rules developed by Lipinski and co-workers for assessing the permeability of hydrophobic ion-like drug molecules through biomembranes. It indicates that BG’s increased diffusion rate is due to its higher lipophilicity, with a distribution coefficient 25 times greater than MG. In contrast, CV, despite having similar lipophilicity to MG, shows negligible permeation through the E. coli CM on the observation scale, attributed to its more hydrogen bonding sites and larger polar surface area. Importantly, cell viability tests revealed that BG’s antimicrobial efficacy is ∼2.4 times greater than that of MG, which aligns well with its enhanced diffusion into the E. coli cytosol. These findings offer valuable insights for drug design and development, especially for improving the permeability of poorly permeable drug molecules.

Ultra-high volume expansion ratio branched PBT/TPEE three-dimensional reticulated foams of supercritical CO2 melt foaming for efficient oil/water separation

The development of polymer reticulated foams with high expansion ratios (VER) for selective oil-adsorption applications has been hindered by technical challenges. In this article, high VER reticulated foam with outstanding selective oil-adsorption performance was realized through the synergistic effect of molecular topological structure and blending heterostructure. Branched polybutylene terephthalate(B-PBT)/thermoplastic polyester elastomer(TPEE) was prepared by blending reaction. Then, B-PBT/TPEE blends were foamed by supercritical CO2 melting foaming, a solvent-free process. The nano-scale TPEE, acting as the weak point, induced the cell wall to rupture and form reticulated foam after the B-PBT had expanded to a high VER. The branching topological structure endowed PBT high storage modulus(G’) and complex viscosity(η*), which support the expansion of foam and keep foam from collapsing before the melt solidification. As a result, ultra-high VER three-dimensional reticulated foams possessing VER of 46.9 and open-cell content of 97.8 % were prepared, which is higher about 200 % than the previous research. The water contact angle of reticulated foams is 132° and cyclohexane droplets diffuse into reticulated foam showing the contact angle of 0°, indicating the reticulated foam have oleophilicity and hydrophobicity. The adsorption capacity of the reticulated foam for various oils is from 24 to 67 g/g. Moreover, the adsorption rate constant of reticulated foam is 8 times more than that of conventional open-cell foam. These benefits from the unique cell structure and high VER of reticulated foam. The work provides a facile and novel method for the green preparation of high-performance oil/water separation materials.

Molecular simulations of amine-based organic additives at a steel surface: Effect of the internal molecular structure on adsorption

Lubricating oils mitigate wear in gears and rolling bearings lengthening the lifespan of drivetrain units for electric vehicles. Amine-based organic additives from the lubricating oil contribute to alleviating wear by adsorbing on rubbing steel surfaces of mechanical contacts and forming anti-wear films. Cross-pin wear experiments suggest that additives with branches in polar heads improve wear protection, while remaining environmentally friendly. Experiments show a reasonable correlation with the energy of adsorption calculated from molecular dynamics simulations at large surface coverages. Whereas adsorption strengths and surface coverages are barely affected by the conformation of alkyl chains (cis/trans), they are affected by the length of branches in polar heads of additives. Results suggest better performances for branch lengths containing 3–4 C atoms.

Wettability of a Polymethylmethacrylate Surface by Fluorocarbon Surfactant Solutions

To clarify the adsorption behavior of fluorocarbon surfactants on PMMA surfaces, the contact angles of two nonionic fluorocarbon surfactants (FNS-1 and FNS-2) and an anionic fluorocarbon surfactant (FAS) on polymethylmethacrylate (PMMA) surface were determined using the sessile drop method. Moreover, the effects of molecular structures on the surface tension, adhesion tension, solid–liquid interfacial tension, and adhesion work of the three fluorocarbon surfactants were investigated. The results demonstrate that the adsorption amounts for three fluorocarbon surfactants at the air–water interface are 4~5 times higher than those at the PMMA–solution interface. The three fluorocarbon surfactants adsorb on the PMMA surface by polar groups before CMC and by hydrophobic chains after CMC. Before CMC, FNS-2 with the smallest molecular size owns the highest adsorption amount, while FAS with large-branched chains and electrostatic repulsion has the smallest adsorption amount. After CMC, the three fluorocarbon surfactants form aggregates at the PMMA-liquid interface. FAS possesses the smallest adsorption amount after CMC. Besides, FNS-1 possesses a higher adsorption amount than FNS-2 due to the longer fluorocarbon chain and the lower CMC value of FNS-1. The adsorption behaviors of nonionic and anionic fluorocarbon surfactants on the PMMA surface are different. FAS forms interfacial aggregates before CMC, which may be attributed to the electrostatic interaction between the anionic head of FAS and the PMMA surface.

High-Pressure CO2 and CH4 Transport in Smooth Crystalline Silica Mesopores: A Molecular Dynamics Study.

In this study, we use molecular dynamics (MD) simulation to study pressure-driven CO2 and CH4 flows and their slippage behaviors in β-cristobalite mesopores. The result illustrates that both CO2 and CH4 have an apparent adsorption layer on pore surface. However, significant differences in gas slippage are observed: CH4 flow shows considerable slippage, while it is negligible for CO2 flow. This disparity is attributed to the collective effect of gas molecular configurations and surface structure. The linear molecular structure of CO2 allows it to align perpendicular to the surface, even penetrating into the surface. Notably, the perpendicular orientation of CO2 molecules is energetically favored near the center of the equilateral triangle formed by adjacent oxygen atoms on β-cristobalite surface. Conversely, the symmetric molecular structure of CH4, coupled with its larger size, prevents its penetration into pore surfaces. Therefore, despite smooth crystalline surfaces, CO2 topological accessible plane is much more curved than that of CH4. Consequently, CO2 displays hesitating motions undergoing rotational movements, which significantly hinders its slippage. This study highlights the collective influences of gas molecular characteristics and surface structure on gas slippage, affording important insights into gas sequestration and the development of functional materials for gas separation.

Construction of Pickering emulsions stabilized by small molecular bioactive nanocrystals: Crosstalk between bioactive molecular structure and initial aqueous phase

Pickering emulsions stabilized with bioactive nanocrystals (BNC-PEs) have attracted increasing attentions in recent years. However, the mechanisms for the construction of stable BNC-PEs remain obscure. This study aimed to investigate the effects of the bioactive molecular structure and the initial pH of the aqueous phase on the fabrication and stability of BNC-PEs and the crosstalk between the two factors. Puerarin, tanshinone IIA and ferulic acid with unique structural characteristics were employed as model components to prepare BNC-PEs. Results showed that the initial pH of the aqueous phase significantly affected the stability of BNC-PEs through influencing the particle sizes and charges of nanocrystals, while the molecular structure of bioactive substances affected the three-phase contact angles or interfacial tensions. The construction and stability of the three kinds of BNC-PEs were all improved with increasing initial pH of the aqueous phase. Moreover, it was first found that the bioactive molecular structure strongly interfered with the influences of the initial pH of the aqueous phase on the stability of BNC-PEs. This study demonstrated for the first time that there might be a crosstalk between the bioactive molecular structure and the initial pH of the aqueous phase, and that the optimal pH of the aqueous phase might be intricately linked to the molecular structure of bioactive nanocrystals for BNC-PEs.

Synthesis and characterization of new perylenediimide derivatives: Promising low-cost electron transport materials for perovskite solar cells

In organic-inorganic perovskite solar cells (PSCs), the electron transport layer (ETL) plays a crucial role providing efficient electron extraction and transport required for achieving high device performance. Compared to traditional fullerene-based electron-transport materials (ETMs), non-fullerene small molecules have attracted much attention due to their tunable optoelectronic properties, lower cost, and much higher stability. In this work, we synthesized and characterized four perylenediimide (PDI) derivatives and investigated their optoelectronic properties in the context of application as ETMs for PSCs. To establish the compatibility of PDI films with perovskite absorber material, the surface properties of Cs0.12FA0.88PbI3/PDI bilayer stacks were studied using contact angle and infrared scattering scanning near-field microscopy methods. A study of the photochemical stability of these bilayer stacks showed that coating the perovskite film with a layer of PDI improves its tolerance with respect to light. Utilizing these molecules as ETMs in the inverted p-i-n PSCs delivered light power conversion efficiencies ranging from 11.1 % to 15.4 %, thus indicating the considerable effect of the PDI derivative molecular structure on the photovoltaic properties. Further development of this research direction may lead to the rational design of advanced PDI-based electron transport materials for efficient and stable PSCs.

Extrusion can ameliorate negative effects of molecular structures of brewer's spent grain on energy contents and amino acid digestibility in growing pigs.

The objectives of this study were to investigate the effects of extrusion on the chemical compositions, surface structure, and molecular structure of brewer's spent grain (BSG), as well as to determine the digestible energy (DE), metabolizable energy (ME), apparent total tract digestibility (ATTD) of nutrients and energy, and amino acid (AA) digestibility of extruded BSG when fed to growing pigs. Firstly, we determined the changes in chemical compositions and molecular structure of both non-extruded and extruded BSG. In Exp. 1, eighteen growing pigs were fed three different diets including one corn-soybean meal basal diet and two experimental diets containing 20% BSG with or without extrusion. Feces and urine were collected to determine the ATTD of nutrients and energy, DE, and ME of extruded or non-extruded BSG. In Exp. 2, eighteen growing pigs were fed three different diets including 30% BSG with or without extrusion, and an N-free diet. Ileal digesta was collected through the slaughter method to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of AA of extruded or non-extruded BSG. The results showed that extrusion reduced the neutral detergent fiber, hemicellulose and cellulose contents in BSG, and increased the Arg, Asp, Glu, Ser, Tyr, total indispensable AA and total AA contents of BSG, altered the surface structure of BSG, increased the peak absorbance in amide I and amide II height, amide II and amide (I+II) area, α-helix height, decreased β-sheet height, and weakened band intensities in cellulosic compounds (CELC) area, structural carbohydrates (SCHO) area, carbohydrates area (CHO) peak 2 and 3 height, the area ratio of CELC: CHO and CELC: SCHO. Moreover, DE and ME values and ATTD of energy, dry matter, crude protein, acid detergent fiber, neutral detergent fiber, cellulose and hemicellulose increased (P < 0.05) when pigs were fed extruded BSG diets. The AID and SID of Arg, His, Lys, Val and Gly increased, whereas the AID and SID of Ile and Leu decreased when pigs were fed extrusion diets (P < 0.05). Our study found that the ATTD of nutrients and AA digestibility in pigs were positively correlated with the molecular structure of proteins, and negatively correlated with the molecular structure of carbohydrates (P < 0.05). These findings suggested that extrusion had the potential to improve the nutrient digestibility of BSG by altering its chemical compositions, surface structure, and molecular structure.

Effects of molecular structure and temperature field on the crystallization behavior of poly(tetrafluoroethylene-co-perfluoroalkylvinyl ether)

Despite the wide industrial application of poly(tetrafluoroethylene-co-perfluoroalkylvinyl ether) (PFA) in semiconductor processing, its crystallization behavior has little been studied. In this work, three PFA resins with similar molecular weight but different comonomer content and distribution were synthetized. Then the non-isothermal crystallization kinetics and crystalline structures were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction systematically. It is found that the incorporation of comonomers destroys the chain regularity and reduces the crystallizability of PFA thermodynamically, while the comonomer insertion improves the chain flexibility to accelerate the crystal growth dynamically. When the comonomer content of PFA is low, both the nucleation and growth rates are quite fast, which is favorable for the formation of spherulite. As the comonomer content increases or distribute uniformly in the chain, the nucleation rate declines notably and the side groups distort the crystal cell to increase the spacing of [100] plane. Moreover, two-dimensional growth mode is dominant to form bundle-like structure when crystallizing at slow cooling, where nucleation is suppressed by growth. But three-dimensional symmetrical spherulite can be activated and perfected at high cooling rate due to the initiation of substantial nucleation sites. This unique crystallization behavior is opposite to that of conventional polymers, providing a guidance for the polymerization and processing of PFA.

Effects of Oxygen Concentration on Soot Formation in Ethylene and Ethane Fuel Laminar Diffusion Flames

In studying the effects of oxygen concentration and molecular structure on the morphologies of the soot particles produced by hydrocarbon fuels, ethylene and ethane were chosen as experimental fuels. With a Gülde laminar coaxial diffusion flame device, a soot particle device was used to sample soot particles at different oxygen concentrations (21%, 24%, 26%, 28%, and 31%) and at different heights above a burner (HABs = 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm). High-resolution transmission electron microscopy (HRTEM) was used to scrutinize and analyze the soot particles at varying oxygen concentrations. The findings suggest that at the same oxygen concentration, ethylene produces brighter and taller flames. With an increase in the oxygen concentration, ethylene flames and ethane flames gradually decrease in height and become brighter. With an increase in the HAB, the average primary soot particle diameter (Dp) increases initially and then decreases, the fractal dimension (Df) increases, and the aggregates transition from strips and chains to clusters. At the same flame height (HAB = 30 mm), the Dp decreases, the Df increases, the carbon layer torsion resistance (Tf) and the carbon layer spacing (Ds) increase, and the carbon layer changes from a parallel arrangement to a curved arrangement to form denser network aggregations.

The effect of molecular structure of imidazole-based compounds on corrosion inhibition of Cu, Zn, and Cu-Zn alloys

Three imidazole-based compounds (imidazole, 2-mercaptobenzimidazole, and 2-mercapto-1-methylbenzimidazole) were studied as corrosion inhibitors of Cu, Zn, and a family of Cu-xZn brass alloys (x = 10−40 wt%) in 3 wt% NaCl solution. The composition of inhibitor layers on the surface was studied using X-ray photoelectron and infrared spectroscopies. The molecular adsorption modes on Cu and Zn were modelled using density-functional theory (DFT) calculations. Mercapto-based inhibitors act as efficient inhibitors on all materials studied due to the formation of inhibitor layer through bonding with nitrogen and sulphur atoms. In contrast, imidazole is a moderate inhibitor for Zn, while it is much less efficient for Cu.

Effect of molecular structure on the dynamics and viscoelasticity of vitrimers

Vitrimers are a class of dynamic polymer networks that perform bond-exchange reactions (BERs) under environmental stimuli while preserving network connectivity. The viscoelastic properties of vitrimers are not only dependent on the kinetics of BERs, but also the architectures of polymer matrix. Here, we investigate the influence of polymer architectures on the dynamics and linear viscoelasticity of vitrimers through varying the sticker (reactive bead) distribution in the precursor chain and the BERs energy barrier (Ub) by performing hybrid molecular dynamics-Monte Carlo simulations. Increasing Ub, vitrimers with block and gradient distributions exhibit considerably faster relaxations of chain ends, Rouse mode, and stress and lower zero-shear viscosity than the analogs with random and uniform distributions, in qualitative agreement with the predictions of the sticky Rouse model. In contrast, the distribution of stickers has a small influence on the relaxation of dynamic bonds regardless of the Ub value. By comparing the molecular structures of vitrimers with different distributions of stickers, we find that the molecular defects, especially the relatively longer dangling end in block and gradient distributions, impair the effect of dynamic bonds on the dynamics and viscoelasticity of vitrimers. This suggests that the dangling defects can be leveraged for further development of recyclable and healable materials with fast stress relaxation and improved flowability.

Effect of molecular weight and chemical structure of plasticizer on suspension property, binder removal, and sintered performance for zirconia toughened alumina ceramics fabricated by vat photopolymerization

Adding plasticizer is an appealing strategy to optimize binder removal for ceramic components fabricated by vat photopolymerization (VPP). However, so far the studies for effect mechanism of plasticizer on whole technological process of VPP are comparatively very limited, especially through analysis of physical and chemical properties of plasticizers. Herein, the effect of molecular weight and chemical structure of plasticizer on suspension property, binder removal, and sintered performance of zirconia toughened alumina (ZTA) ceramics was comprehensively investigated. Two types of plasticizers, namely, polyethylene glycol (PEG) and polypropylene glycol (PPG), with various molecular weights from 200 to 600 were used. Interestingly, only after adding PEG200 or PPG200, the suspensions still exhibited desired rheological and photocuring behavior, and the superior surface quality was still observed. More importantly, PPG200 proved to be the most effective plasticizer to achieve the most excellent and stable mechanical performances, as well as the highest debinding efficiency.

Retention mechanisms of dipeptides on superficially porous particle vancomycin- and teicoplanin-based chiral stationary phases

Chromatographic behavior of new chiral stationary phases (CSPs) Chiral-T and Chiral-V with teicoplanin and vancomycin antibiotics grafted onto superficially porous silica particles was studied in relation to dipeptide (DP) stereoisomers. The unbuffered water–methanol solutions were used as mobile phases (MPs). The effects of physical properties and molecular structure of analytes and selectors on retention and separation of DP stereoisomers are discussed herein. Chiral-T was evinced to exhibit high enantioselectivity, with highest α values attaining 16.5, 18.8 and 20.4 for Gly-Leu, dd/ll-Phe-Leu and ld/dl-Ala-Ala. At this point, Chiral-V did not exhibit enantioselectivity towards DP stereoisomers. The effect of MP composition on retention and enantioseparation of DPs was investigated. Lipophilicity of DPs was found to be an essential factor in the dependence of their retention vs. methanol concentration in МPs. Lipophobic DPs were eluted more quickly by water-rich solvents, with lipophilic DPs exhibiting an asymmetric U-shaped, or a descending dependence of retention factor vs. the methanol percentage on Chiral-T or Chiral-V, respectively. A theoretical model taking into account interaction of both solvents of a binary MP with both an analyte and adsorption sites was successfully applied so as to approximate and interpret the dependences of DP retention (monotonic and U-shaped) vs. a modifier content in MP. Water molecules were evinced to predominantly participate in competitive adsorption with DP molecules. The model predicted better solvation of lipophilic DPs by methanol and better solvation of lipophobic DPs by water. An attempt was made to verify the possibility of modeling by molecular docking the processes occurring during interaction between DP stereoisomers and CSPs, including consideration of the influence of competitive binding of eluent molecules in selector cavity.

Differences and Mechanism of Waxy Corn Starch and Normal Corn Starch in the Preparation of Recrystallized Resistant Starch (RS3).

This study prepared resistant starch (RS) from waxy corn starch and normal corn starch and analyzed the effects of its molecular and microstructural characteristics on RS content. The RS content of waxy corn resistant starch (RS-WCS) was highest at 57.8%, whereas that of normal corn resistant starch (RS-NCS) was 41.46%. The short-chain amylose contents of RS-WCS and RS-NCS were 47.08% and 37.24%, respectively, proportional to their RS content. Additionally, RS content positively correlated with crystallinity, short-range order degree, and degree of polymerization (DP), exceeding 25. Electron microscopic images, before and after enzymolysis, revealed that RS-WCS was hydrolyzed from the surface to the center by pancreatic α-amylase, while RS-NCS underwent simultaneous hydrolysis at the surface and center. These results indicate that the higher RS content in RS-WCS, compared to RS-NCS, is attributable to the synergistic effects of molecular structure and microstructure.