Mechanistic understanding of changes in physicochemical properties of different rice starches under high hydrostatic pressure treatment based on molecular and supramolecular structures.

The molecular and supramolecular structures of japonica and waxy rice starches under high hydrostatic pressure treatment (450 MPa) were studied and the changes in physicochemical properties were analyzed based on these structures. The molecular structures of japonica and waxy rice starch cause differences in the lamellar structure and physicochemical properties. The thickness of amorphous lamella of japonica rice starch increased at 5 min (2.95 nm) followed by a gradual collapse of lamellar structure. Whereas the thickness of crystalline lamellae of waxy rice starch increased at 15 min (5.92 nm) and the lamellae collapsed suddenly at 20 min. The pasting, rheological and textural characteristics of both starches increased significantly within 10 to 15 min. The decreasing onset temperature and enthalpy of high hydrostatic pressure-treated starches indicated easier gelatinization. High hydrostatic pressure-treatment offers potential for developing starch-based products with low swelling capacity, easy gelatinization, high viscosity and hardness.

Spontaneous formation of polymeric nanoribbons in water driven by π-π interactions.

A simple method was developed to produce polymeric nanoribbons and other nanostructures in water. This approach incorporates a perylene diimide (PDI) functionalized by hydrophilic triethylene glycol (TEG) as a hydrophobic supramolecular structure directing unit (SSDU) into the core of hydrophilic poly(N,N-dimethylacrylamide) (PDMAc) chains using RAFT polymerization. All PDI-functional polymers dissolved spontaneously in water, forming different nanostructures depending on the degree of polymerization (DPn): nanoribbons and nanocylinders for DPn = 14 and 22, and spheres for DPn > 50 as determined by cryo-TEM and SAXS analyses. UV-VIS absorption spectroscopy was used to monitor the evolution of the PDI absorption signal upon dissolution. In solid form, all polymers show a H-aggregate absorption signature, but upon dissolution in water, the shortest DPn forming nanoribbons evolved to show HJ-aggregate absorption signals. Over time, the J-aggregate band increased in intensity, while cryo-TEM monitoring evidenced an increase in the nanoribbon's width. Heating the nanoribbons above 60 °C, triggered a morphological transition from nanoribbons to nanocylinders, due to the disappearance of J-aggregates, while H-aggregates were maintained. The study shows that the TEG-PDI is a powerful SSDU to promote 2D or 1D self-assembly of polymers depending on DPn through simple dissolution in water.

Structure and Characterization of Catanionic Complexes and Biocompatible Vesicles of N-Acyltaurine and Sarcosine Alkyl Ester: Encapsulation and Release Studies with 5-Fluorouracil.

Hydrated dispersions containing equimolar mixtures of cationic and anionic amphiphiles, referred to as catanionic systems, exhibit synergistic physicochemical properties, and mixing single-chain cationic and anionic lipids can lead to the spontaneous formation of vesicles as well as other phase structures. In the present work, we have characterized two catanionic systems prepared by mixing N-acyltaurines (NATs) and sarcosine alkyl esters (SAEs) bearing 11 and 12 C atoms in the acyl/alkyl chains. Turbidimetric and isothermal titration calorimetric studies revealed that both NATs form equimolar complexes with SAEs having matching acyl/alkyl chains. The three-dimensional structure of the sarcosine lauryl ester (lauryl sarcosinate, LS)-N-lauroyltaurine (NLT) equimolar complex has been determined by single-crystal X-ray diffraction. The LS-NLT equimolar complex is stabilized by electrostatic attraction and multiple hydrogen bonds, including classical, strong N-H···O hydrogen bonds as well as several C-H···O hydrogen bonds between the two amphiphiles. DSC studies showed that both equimolar complexes show single sharp phase transitions. Transmission electron microscopy and dynamic light scattering studies have demonstrated that the LS-NLT catanionic complex assemblies yield stable medium-sized vesicles (diameter 280-350 nm). These liposomes were disrupted at high pH, suggesting that the designed catanionic complexes can be used to develop base-labile drug delivery systems. In vitro studies with these catanionic liposomes showed efficient entrapment (73% loading) and release of the anticancer drug 5-fluorouracil in the physiologically relevant pH range of 6.0-8.0. The release rate was highest at pH 8.0, reaching about 78%, 90%, and 100% drug release at 2, 6, and 12 h, respectively. These observations indicate that LS-NLT catanionic vesicles will be useful for designing drug delivery systems, particularly for targeting organs such as the colon, which are inherently at basic pH.

Expression of chiral molecular and supramolecular structure on enantioselective catalytic activity.

Understanding the structure-function relationships encoded on chiral catalysts is important for investigating the fundamental principles of catalytic enantioselectivity. Herein, the synthesis and self-assembly of naphthalene substituted bis-l/d-histidine amphiphiles (bis-l/d-NapHis) in DMF/water solution mixture is reported. The resulting supramolecular assemblies featuring well-defined P/M nanoribbons (NRs). With combination of the (P/M)-NR and metal ion catalytic centers (Mn+ = Co2+, Cu2+, Fe3+), the (P)-NR-Mn+ as chiral supramolecular catalysts show catalytic preference to 3,4-dihydroxy-S-phenylalanine (S-DOPA) oxidation while the (M)-NR-Mn+ show enantioselective bias to R-DOPA oxidation. In contrast, their monomeric counterparts bis-l/d-NapHis-Mn+ display an inverse and dramatically lower catalytic selectivity in the R/S-DOPA oxidation. Among them, the Co2+-coordinated supramolecular nanostructures show the highest catalytic efficiency and enantioselectivity (select factor up to 2.70), while the Fe3+-coordinated monomeric ones show nearly racemic products. Analysis of the kinetic results suggests that the synergistic effect between metal ions and the chiral supramolecular NRs can significantly regulate the enantioselective catalytic activity, while the metal ion-mediated monomeric bis-l/d-NapHis were less active. The studies on association constants and activation energies reveal the difference in catalytic efficiency and enantioselectivity resulting from the different energy barriers and binding affinities existed between the chiral molecular/supramolecular structures and R/S-DOPA enantiomers. This work clarifies the correlation between chiral molecular/supramolecular structures and enantioselective catalytic activity, shedding new light on the rational design of chiral catalysts with outstanding enantioselectivity.

Design, fabrication, and evaluation of keratin and pectin incorporated supramolecular structured zero-oxidation state selenium nanogel blended 3D printed transdermal patch.

This study investigates the synthesis of selenium nanoparticles (SeNPs), owing to the low cost and abundance of selenium. However, the toxicity of SeNP prompts the development of a selenium nanocomposite (SeNC) containing pectin, keratin, and ferulic acid to improve the bioactivity of Se[0]. Further, incorporating the SeNC in a suitable formulation for drug delivery as a transdermal patch was worth studying. Accordingly, various analytical techniques were used to characterize the SeNPs and the SeNC, confirming successful synthesis and encapsulation. The SeNC exhibited notable particle size of 448.2 ± 50.2 nm, high encapsulation efficiency (98.90 % ± 2.4 %), 28.1 ± 0.45 drug loading, and sustained drug release at pH 5.5. Zeta potential and XPS confirmed the zero-oxidation state. The supramolecular structure was evident from spectral analysis endorsing the semi-crystalline nature of the SeNC and SEM images showcasing flower-shaped structures. Further, the SeNC demonstrated sustained drug release (approx. 22 % at 48 h) and wound-healing potential in L929 fibroblast cells. Subsequently, the SeNC loaded into a gelling agent exhibited shear thinning properties and improved drug release by nearly 58 %. A 3D printed reservoir-type transdermal patch was developed utilizing the SeNC-loaded gel, surpassing commercially available patches in characteristics such as % moisture uptake, tensile strength, and hydrophobicity. The patch, evaluated through permeation studies and CAM assay, exhibited controlled drug release and angiogenic properties for enhanced wound healing. The study concludes that this patch can serve as a smart dressing with tailored functionality for different wound stages, offering a promising novel drug delivery system for wound healing.

Influence of Low-Molecular-Weight Esters on Melt Spinning and Structure of Poly(lactic acid) Fibers.

Poly(lactic acid) has great potential in sectors where degradability is an important advantage due to its polymer nature. The medical, pharmaceutical, and packaging industries have shown interest in using PLA. To overcome the limitations of stiffness and brittleness in the polymer, researchers have conducted numerous modifications to develop fibers with improved properties. One such modification involves using plasticizing modifiers that can provide additional and desired properties. The scientific reports indicate that low-molecular-weight esters (LME) (triethyl citrate and bis (2-ethylhexyl) adipate) affect the plasticization of PLA. However, the research is limited to flat structures, such as films, casts, and extruded shapes. A study was conducted to investigate the impact of esters on the process of forming, the properties, and the morphology of fibers formed through the melt-spinning method. It was found that the modified PLA required different spinning and drawing conditions compared to the unmodified polymer. DSC, FTIR, WAXD, and GPC/SEC analyses were performed for the modified fibers. Mechanical tests and morphology evaluations using SEM microscopy were also conducted. The applied plasticizers lowered the temperature of the spinning process by 40 °C, and allowed us to obtain a higher degree of crystallinity and a better tenacity at a lower draw ratio. GPC/SEC analysis confirmed that the polymer-plasticizer interaction is physical because the booth plasticizer peaks were separated in the chromatographic columns. The use of LME in fibers significantly reduces the temperature of the spinning process, which reduces production costs. Additives significantly change the production process and the structure of the fiber depending on their rate, which may affect the properties, e.g., the rate of degradation. We can master the degree of crystallinity through the variable amount of LME. The degree of crystallization of the polymers has a significant influence on polymer application.

Unrevealing the influence of reagent properties on disruption and digestibility of lignocellulosic biomass during alkaline pretreatment.

Beyond the conventional consideration of pretreatment severity (PS) responsible for biomass disruption, the influence of reagent properties on biomass (LCB) disruption is often overlooked. To investigate the LCB disruption as a function of reagent properties, reagents with distinct cations (NaOH and KOH) and significantly higher delignification potential were chosen. NaOH solution (3 % w/v) with a measured pH of 13.05 ± 0.01 is considered the reference, against which a KOH solution (pH = 13.05 ± 0.01) was prepared for LCB pretreatment under the same PS. Despite comparable lignin content, varying glucose yield of NaOH (68.76 %) and KOH (46.88 %) pretreated residues indicated the presence of heterogeneously disrupted substrate. Holocellulose extracted from raw poplar (ASC, control) and alkaline pretreated residues (C-NaOH and C-KOH) were analyzed using HPLC, XRD, SEM, TGA/DTG, XPS, and 13CP MAS NMR to investigate the pretreatment-induced structural modification. Results revealed that, despite the same pretreatment severity, better disruption in C-NaOH (higher accessible fibril surface and less-ordered region) leading to higher digestibility than C-KOH, likely due to the smaller ionic radius of Na+, facilitates better penetration into dense LCB matrix. This study elucidates the importance of considering the reagent properties during LCB pretreatment, eventually enhancing consciousness while selecting reagents for efficient LCB utilization.

A strong and tough supramolecular assembled ß-cyclodextrin and chitin nanocrystals protein adhesive: Synthesis, characterization, bonding performance on three-layer plywood.

The development of a biomass adhesive as a substitute for petroleum-derived adhesives has been considered a viable option. However, achieving both superior bonding strength and toughness in biomass adhesives remains a significant challenge. Inspired by the human skeletal muscles structure, this study reveals a promising supramolecular structure using tannin acid (TA) functionalized poly-ß-cyclodextrin (PCD) (TA@PCD) as elastic tissues and chitin nanocrystals (ChNCs) as green reinforcements to strengthen the soybean meal (SM) adhesive crosslinking network. TA@PCD acts as a dynamic crosslinker that facilitates reversible host-guest interactions, hydrogen bonds, and electrostatic interactions between adjacent stiff ChNCs and SM matrix, resulting in satisfactory strength and toughness. The resulting SM/TA@PCD/ChNCs-2 adhesive has demonstrated satisfactory wet and dry shear strength (1.25 MPa and 2.57 MPa, respectively), toughness (0.69 J), and long-term solvents resistance (80 d). Furthermore, the adhesive can exhibit desirable antimildew characteristics owing to the phenol hydroxyl groups of TA and amino groups of ChNCs. This work showcases an effective supramolecular chemistry strategy for fabricating high-performance biomass adhesives with great potential for practical applications.

Effect of fibers on starch structural changes during hydrothermal treatment: multiscale analyses, and evaluation of dilution effects on starch digestibility.

BACKGROUND: Dietary fibers (DFs) may influence the structural, nutritional and techno-functional properties of starch within food systems. Moreover, DFs have favorable effects on the digestive system and potentially a lower glycemic index. These potential benefits may change depending on DF type. Starch processed in the presence of soluble and insoluble fibers can undergo different structural and functional changes, and the present study investigated the effects of short-chain and long-chain inulin and cellulose on the structural and digestive properties of wheat starch. RESULTS: The combined use of differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) provided insights into the structural changes in starch and inulin at different levels. Short-chain and long-chain inulin had higher water retention capacity and a potential to limit starch gelatinization. The FTIR results revealed an interaction between starch and inulin. Scanning electron microscopy analysis showed morphological changes in starch and inulin after the hydrothermal treatment. Cellulose fiber was not affected by the hydrothermal treatment and had no influence on starch behavior. The structural differences observed through XRD, FTIR and scanning electron microscopy analyses between starch with and without inulin fibers did not significantly impact starch digestibility, except for the dilution effect caused by adding DFs. CONCLUSION: The present study highlights the importance of utilizing different analytical tools to assess changes in food samples at different scales. Although short-chain and long-chain inulin could potentially limit starch gelatinization, the duration of the heat treatment (90 °C for 10 min) was sufficient to ensure complete starch gelatinization. The dilution effect caused by adding fibers was the primary reason for the effect on starch digestibility. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Heat-moisture treated waxy highland barley starch: Roles of starch granule-associated surface lipids, temperature and moisture.

Roles of temperature, moisture and starch granule-associated surface lipids (SGASL) during heat-moisture treatment (HMT) of waxy highland barley starch were elucidated. Starch without SGASL showed a higher increase in ratio (1016/993 cm-1) (0.095-0.121), lamellar peak area (88), radius of gyration (Rg1, 0.9-1.8 nm) and power-law exponents (0.19-0.42) than native starch (0.038-0.047, 46, 0.1-0.6 nm, 0.04-0.14), upon the same increase in moisture or temperature. Thus, removing SGASL promoted HMT. However, after HMT (30 % moisture, 120 °C), native starch showed lower relative crystallinity (RC, 11.67 %) and lamellar peak area (165.0), longer lamellar long period (L, 14.99 nm), and higher increase in peak gelatinization temperature (9.2-13.3 °C) than starch without SGASL (12.04 %, 399.2, 14.52 nm, 4.7-6.1 °C). This suggested that the resulting SGASL-amylopectin interaction further destroyed starch structure. Starch with and without SGASL showed similar trends in RC, lamellar peak area, L and Rg1 with increasing temperature, but different trends with increasing moisture, suggesting that removing SGASL led to more responsiveness to the effects of increasing moisture. Removing SGASL resulted in similar trends (RC and lamellar peak area) with increasing moisture and temperature, suggesting that the presence of SGASL induced different effects on moisture and temperature.

Biodegradation of aliphatic polyurethane foams in soil: Influence of amide linkages and supramolecular structure.

Polyurethane (PU) foams are classified as physically nonrecyclable thermosets. The current effort of sustainable and eco-friendly production makes it essential to explore methods of better waste management, for instance by modifying the structure of these frequently used polymers to enhance their microbial degradability. The presence of ester links is known to be a crucial prerequisite for the biodegradability of PU foams. However, the impact of other hydrolysable groups (urethane, urea and amide) occurred in PU materials, as well as the supramolecular structure of the PU network and the cellular morphology of PU foams, is still relatively unexplored. In this work, fully aliphatic PU foams with and without hydrolyzable amide linkages were prepared and their aerobic biodegradation was investigated using a six-month soil burial test. Besides the variable chemical composition of the PU foams, the influence of their different supramolecular arrangement and cellular morphologies on the extent of biodegradation was also evaluated. Throughout the soil burial test, the release of carbon dioxide, and enzyme activities of proteases, esterases, and ureases were measured. At the same time, phospho-lipid fatty acids (PLFA) analysis was conducted together with an assessment of microbial community composition achieved by analysing the genetic information from the 16S rRNA gene and ITS2 region sequencing. The results revealed a mineralization rate of 30-50 % for the PU foams, indicating a significant level of degradation as well as indicating that PU foams can be utilized by soil microorganisms as a source of both energy and nutrients. Importantly, microbial biomass remained unaffected, suggesting that there was no toxicity associated with the degradation products of the PU foams. It was further confirmed that ester linkages in PU foam structure were easily enzymatically cleavable, while amide linkages were not prone to degradation by soil microorganisms. In addition, it was shown that the presence of amide linkages in PU foam leads to a change in the supramolecular network arrangement due to increased content of hard segments, which in turn reduces the biodegradability of PU foam. These findings show that it is important to consider both chemical composition and supramolecular/macroscopic structure when designing new PU materials in an effort to develop environmentally friendly alternatives.

Structural studies of supramolecular complexes and assemblies by ion mobility mass spectrometry.

Recent advances in instrumentation and development of computational strategies for ion mobility mass spectrometry (IM-MS) studies have contributed to an extensive growth in the application of this analytical technique to comprehensive structural description of supramolecular systems. Apart from the benefits of IM-MS for interrogation of intrinsic properties of noncovalent aggregates in the experimental gas-phase environment, its merits for the description of native structural aspects, under the premises of having maintained the noncovalent interactions innate upon the ionization process, have attracted even more attention and gained increasing interest in the scientific community. Thus, various types of supramolecular complexes and assemblies relevant for biological, medical, material, and environmental sciences have been characterized so far by IM-MS supported by computational chemistry. This review covers the state-of-the-art in this field and discusses experimental methods and accompanying computational approaches for assessing the reliable three-dimensional structural elucidation of supramolecular complexes and assemblies by IM-MS.

Self-assembling peptides: Perspectives regarding biotechnological applications and vaccine development.

Self-assembly involves a set of molecules spontaneously interacting in a highly coordinated and dynamic manner to form a specific supramolecular structure having new and clearly defined properties. Many examples of this occur in nature and many more came from research laboratories, with their number increasing every day via ongoing research concerning complex biomolecules and the possibility of harnessing it when developing new applications. As a phenomenon, self-assembly has been described on very different types of molecules (biomolecules including), so this review focuses on what is known about peptide self-assembly, its origins, the forces behind it, how the properties of the resulting material can be tuned in relation to experimental considerations, some biotechnological applications (in which the main protagonists are peptide sequences capable of self-assembly) and what is yet to be tuned regarding their research and development.

In vivo MR imaging for tumor-associated initial neovascularization by supramolecular contrast agents.

Microvascular imaging is required to understand tumor angiogenesis development; however, an appropriate whole-body imaging method has not yet been established. Here, we successfully developed a supramolecular magnetic resonance (MR) contrast agent for long-term whole-tissue observation in a single individual. Fluorescein- and Gd-chelate-conjugated polyethylene glycols (PEGs) were synthesized, and their structures were optimized. Spectroscopic and pharmacokinetic analyses suggested that the fluorescein-conjugated linear and 8-arm PEGs with a molecular weight of approximately 10 kDa were suitable to form a supramolecular structure to visualize the microvessel structure and blood circulation. Microvascular formation was evaluated in a glioma cell transplantation model, and neovascularization around the glioma tissue at 5 days was observed, with the contrast agent leaking out into the cancer tissue. In contrast, after 12 days, microvessel structures were formed inside the glioma tissue, but the agents did not leak out. These imaging data for the first time proved that the microvessels formed inside cancer tissues at the early stage are very leaky, but that they form continuous microvessels after 12 days.

Testing the Performance of the Azo-Polyimide Supramolecular Systems as Substrate for Sensors Based on Platinum Electrodes.

Azo-polyimide films with supramolecular structure were obtained by casting onto glass plates a mixture based on polyamidic acid and different quantities of azochromophore, followed by thermal treatment to realize the final azo-polyimide structure. The dielectric characteristics of the supramolecular structure of polymer films were investigated by broad-band dielectric spectroscopy measurements at different temperatures and frequencies. The free-standing films proved to be flexible and tough and maintained their integrity after repeated bending. The work of adhesion at the polymer/platinum interface was calculated after the evaluation of the surface energy parameters before and after plasma treatment. Atomic force microscopy was used to image the surface morphology, the evolution of the roughness parameters, and the adhesion force between the platinum-covered tip and the polymer surface, registered at the nanoscale with the quantity of the azo dye introduced in the system. The simulation of the columnar growth of a platinum layer was made to provide information about the deposition parameters that should be used for optimal results in the deposition of platinum electrodes for sensors.

Synthesis, Structure, Hirshfeld Surface Analysis, Non-Covalent Interaction, and In Silico Studies of 4-Hydroxy-1-[(4-Nitrophenyl)Sulfonyl]Pyrrolidine-2-Carboxyllic Acid.

The new compound 4-hydroxy-1-[(4-nitrophenyl)sulfonyl]pyrrolidine-2-carboxyllic acid was obtained by the reaction of 4-hydroxyproline with 4-nitrobenzenesulfonyl chloride. The compound was characterized using single crystal X-ray diffraction studies. Spectroscopic methods including NMR, FTIR, ES-MS, and UV were employed for further structural analysis of the synthesized compound. The title compound was found to have crystallized in an orthorhombic crystal system with space group P212121. The S1-N1 bond length of 1.628 (2) Å was a strong indication of the formation of the title compound. The absence of characteristic downfield 1H NMR peak of pyrrolidine ring and the presence of S-N stretching vibration at 857.82 cm-1 on the FTIR are strong indications for the formation of the sulfonamide. The experimental study was complemented with computations at the B3LYP/6-311G + + (d,p) level of theory to gain more understanding of interactions in the compound at the molecular level. Noncovalent interaction, Hirsfeld surface analysis and interaction energy calculations were employed in the analysis of the supramolecular architecture of the compound. Predicted ADMET parameters, awarded suitable bioavailability credentials, while the molecular docking study indicated that the compound enchants promising inhibition prospects against dihydropteroate synthase, DNA topoisomerase, and SARS-CoV-2 spike. Graphical Abstract: Herein we present the solid state structure, noncovalent interaction and spectroscopic analysis of a prospective bioactive compound 4-hydroxy-1-[(4-nitrophenyl)sulphonyl]pyrrolidine-2-carboxyllic acid. Supplementary Information: The online version contains supplementary material available at 10.1007/s10870-023-00978-0.

Structure and Performance of All-Green Electrospun PHB-Based Membrane Fibrous Biomaterials Modified with Hemin.

This work addresses the challenges concerning the development of "all-green" high-performance biodegradable membrane materials based on poly-3-hydroxybutyrate (PHB) and a natural biocompatible functional additive, iron-containing porphyrin, Hemin (Hmi) via modification and surface functionalization. A new facile and versatile approach based on electrospinning (ES) is advanced when modification of the PHB membranes is performed by the addition of low concentrations of Hmi (from 1 to 5 wt.%). Structure and performance of the resultant {HB/Hmi membranes were studied by diverse physicochemical methods, including differential scanning calorimetry, X-ray analysis, scanning electron microscopy, etc. Modification of the PHB fibrous membranes with Hmi allows control over their quality, supramolecular structure, morphology, and surface wettability. As a result of this modification, air and liquid permeability of the modified electrospun materials markedly increases. The proposed approach provides preparation of high-performance all-green membranes with tailored structure and performance for diverse practical applications, including wound healing, comfort textiles, facial protective masks, tissue engineering, water and air purification, etc.

RNA demethylation-driven functional supramolecular structure for label-free detection of m6A modification eraser FTO in human breast tissues.

Fat mass and obesity-associated enzyme (FTO) can dynamically regulate N6-methyladenosine modification, and it is engaged in various cellular functions. Herein, we demonstrate the RNA demethylation-driven functional supramolecular structure for label-free detection of m6A modification eraser FTO in human breast tissues. The presence of FTO catalyzes the removal of methyl group in m6A, causing the cleavage of demethylated DNA by DpnII and the release of DNA primer. The resultant DNA primer hybridizes with circular template to initiate isothermal rolling circle amplification (RCA), producing abundant long ssDNA polymers with repeating sequences of G-quadruplex. Subsequently, N-methylmesoporphyrin IX (NMM) is selectively embedded into G-quadruplex DNAzyme to form a supramolecular NMM-G-quadruplex structure for the generation of an amplified fluorescence signal. Benefiting from high selectivity of DpnII toward demethylated DNA, high amplification efficiency of RCA, and high signal-to-noise ratio of G-quadruplex-NMM system, this assay can sensitively detect FTO with a limit of detection (LOD) of 3.10 × 10-16 M, screen RNA demethylase inhibitors, quantify FTO activity in cancer cells, and discriminate FTO activity between breast cancer patient tissues and healthy person tissues. Importantly, this assay can be homogeneously conducted in a label-free manner, with great potential in RNA demethylases-related pathogenesis research and clinical diagnostics.

Identification of Supramolecular Structures of Porphyrin Polymer on Single-Walled Carbon Nanotube Surface Using Microscopic Imaging Techniques.

Although the supramolecular structure of porphyrin polymers on flat surfaces (i.e., mica and HOPG) has been extensively studied, the self-assembly arrays of porphyrin polymers on the SWNT (as curved nanocarbon surfaces) have yet to be fully identified and/or investigated, especially using microscopic imaging techniques, i.e., scanning tunneling microscopy (STM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). This study reports the identification of the supramolecular structure of poly-[5,15-bis-(3,5-isopentoxyphenyl)-10,20-bis ethynylporphyrinato]-zinc (II) on the SWNT surface using mainly AFM and HR-TEM microscopic imaging techniques. After synthesizing around >900 mer of porphyrin polymer (via Glaser-Hay coupling); the as-prepared porphyrin polymer is then non-covalently adsorbed on SWNT surface. Afterward, the resultant porphyrin/SWNT nanocomposite is then anchored with gold nanoparticles (AuNPs), which are used as a marker, via coordination bonding to produce a porphyrin polymer/AuNPs/SWNT hybrid. The polymer, AuNPs, nanocomposite, and/or nanohybrid are characterized using 1H-NMR, mass spectrometry, UV-visible spectroscopy, AFM, as well as HR-TEM measuring techniques. The self-assembly arrays of porphyrin polymers moieties (marked with AuNPs) prefer to form a coplanar well-ordered, regular, repeated array (rather than wrapping) between neighboring molecules along the polymer chain on the tube surface. This will help with further understanding, designing, and fabricating novel supramolecular architectonics of porphyrin/SWNT-based devices.

Unveiling the retrogradation mechanism of a novel high amylose content starch-Pouteria campechiana seed.

The research of starch retrogradation have been attracting interest. Thereby, the long-term retrogradation mechanism (0-21 days) of Pouteria campechiana seed starch (PCSS) was investigated. The results showed that crystal type was changed from A- to B + V-type during retrogradation. The retrogradation PCSS (RPCSS) exhibited faster retrogradation rate and more compact internal ultra-structure compared to rice, wheat and maize starch. Pearson correlation indicated that, as retrogradation days increased, values of α-1,4-glycosidic bond, A chains, double helix, V-type polymorphism, Mw, relative crystallinity (Rc) and short-range order gradually significantly increased, and B1 chains, B3 + chains values gradually significantly dropped (p < 0.05). These inferred an increasing peak temperature and compactness of morphology with increasing retrogradation days. Compared to native starch, RPCSS α-1.4-glycosidic bond was increased, which indicated that its quick molecules degradation including decreased Mw, B3 + chains, Rc, semicrystalline order, and ΔH. These might provide a theoretical direction for preparation of starch-basis food.