Low Weight Molecules Research Articles

Gravity-driven membrane (GDM) filtration of algae-polluted surface water

This study compared the membrane performances and water quality of gravity-driven membrane (GDM) systems in treating algae-polluted lake water under different operation conditions (microfiltration (MF) vs. ultrafiltration (UF); Chlorella vulgaris (green algae) vs. Phaeodactylum tricornutum (diatom); different algal amounts in the lake water). The results showed the cake layer fouling was predominant in the UF-GDM systems, while irreversible fouling contributed majorly to the MF-GDM fouling. As a result, the UF-GDM systems achieved >1.5 time higher permeate flux compared to the MF-GDM systems in treating algae-polluted lake water. Compared to the green algae, the presence of the diatom cells in the feed water had more negative impacts on the UF permeate flux (increasing the cake layer resistance) and water quality (containing more low molecule weight neutrals). The analysis of cake layer foulants revealed that more aromatic protein-based biopolymers were accumulated on the membranes during filtration of algae-polluted lake water and the biopolymer amounts were almost linearly associated with membrane fouling potential of the GDM systems.

Optical properties of fluidic defect states in one-dimensional graphene-based photonic crystal biosensors: visible and infrared Hall regime sensing

Advances in biotechnology are outpacing studies into the use of graphene in photonic biosensors due to its peculiar optical properties and the successful progress in the nanoscale integration of photonic crystals. Moreover, going beyond the usual Dirac cone approximation for graphene introduces nonlinear effects in graphene’s optics. In this work, by the use of the transfer matrix method, we investigate the effect of hopping parameter on the chemical and biosensing performance of a 1D defective photonic biosensor with a micro/nanofluidic channel as a central defect cavity for biological fluids and gas molecules to flow while interacting with two graphene sheet deposited on silicon dioxide layers of the device. As low-weight molecules absorption on graphene’s surface could affect hopping energy of graphene which plays a significant role in its optical conductivity obtained from the tight-binding model for the visible range, it will serve as a promising tool for the detection of gas and other analytes. We also examine the sensitivity of the defect modes to the changes of the refractive index of the biological fluids under the influence of quantum Hall situation for graphene in terahertz (THz) regime. It is revealed that two defective modes with relatively different sensing properties are emerged within the band stop of the device. The results of this study are not reported elsewhere to the best of our knowledge.

Hollow carbon nanobubbles-coated solid-phase microextraction fibers for the sensitive detection of organic pollutants

Herein, a novel solid-phase microextraction (SPME)fiber based on hollow carbon nanobubbles was developed for the analysis of persistent organic pollutants. The hollow carbon nanobubbles (HCNBs), derived from the nanoscale zeoliticimidazolate framework (ZIF-8), not only possessed the ZIF-8-like microporous shell but also created an internal space for analytes storage. This architecture was beneficial to accelerating the mass transfer process and enhancing the enrichment capacity towards target analytes. As a result, the sensitivity of this HCNBs based SPME fiber toward analytes (e.g., BTEX, PAHs and PCBs) was 2–180 times higher compared with the commercial fibers (100 μm PDMS, 65 μm PDMS/DVB or 85 μm PA). In addition, owing to the size-selectivity of the microporous shell, the HCNBs-based SPME fiber showed high extraction ability towards target analytes with low molecule weight. Furthermore, the lifespan of the homemade fiber was evaluated to be more than 100 times attributing to the hard and stable carbon framework. Under optimal working conditions, analytical performance of the fiber towards PCBs with varying chlorination degrees showed a wide linear range (0.05–1000 ng L−1) and low LODs (0.0017–0.0042 ng L−1). Finally, the established method was successfully applied to the determinations of PCBs in three environmental water samples with good recoveries (84.5–117.1%).

Atmospheric Pressure Plasma-Treated Carbon Nanowalls’ Surface-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (CNW-SALDI-MS)

Carbon nanowalls (CNWs), vertically standing highly crystallizing graphene sheets, were used in the application of a surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS). The CNW substrates solved the issues on interferences of matrix molecules and alkali metal addition ions in low-weight molecule detection. Before SALDI sample preparations, the hydrophobic CNW was treated by atmospheric pressure plasma for exposing hydrophilicity to the CNWs’ surface. Detection of water soluble amino acids, arginine, was demonstrated.

Preparation of Ethyl Cellulose Microspheres for Sustained Release of Sodium Bicarbonate.

Sustained release of thermal-instable and water-soluble drugs with low molecule weight is a challenge. In this study, sodium bicarbonate was encapsulated in ethyl cellulose microspheres by a novel solid-in-oil-in-oil (S/O/O) emulsification method using acetonitrile/soybean oil as new solvent pairs. Properties of the microspheres such as size, recovery rate, morphology, drug content, and drug release behavior were evaluated to investigate the suitable preparation techniques. In the case of that the ratio of the internal and external oil phase was 1: 9, Tween 80 as a stabilizer resulted in the highest drug content (2.68%) and a good spherical shape of microspheres. After the ratio increased to 1: 4, the microspheres using Tween 80 as the stabilizer also had high drug content (1.96%) and exhibited a sustained release behavior, with 70% of drug released within 12 h and a sustained release of more than 40 h. Otherwise, different emulsification temperatures at which acetonitrile was evaporated could influence the drug release behaviour of microspheres obtained. This novel method is a potential and effective method to achieve the encapsulation and the sustained release of thermal-instable and water-soluble drugs with low molecule weight.

Analysis of 4(5)-methylimidazole in soy sauce by a quick, easy, cheap, effective, rugged, and safe approach and liquid chromatography-mass spectrometry

4(5)-Methylimidazole (4(5)-MI) is a potential carcinogen with low molecule weight, highly polarity, and weak basicity. The traditional way to extract and clean-up 4(5)-MI in soy sauce using solid phase extraction is tedious and time consuming. Here we proposed a method for the determination of 4(5)-MI in soy sauce by combining a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction with liquid chromatography-mass spectrometry analysis. The impacts of solution pH, water addition, and cleanup procedure on 4(5)-MI extraction efficiency were studied. An optimized sample preparation approach involved a single step liquid-liquid extraction between acetonitrile and soy sauce under alkaline conditions, followed by primary and secondary amine clean-up. The analytical method was validated with soy sauce at three spiking levels (10, 50, 500 ng/g). The method recovery (96.2–107%) and intra-day/inter-day precision (4.1–8.4%/6.9–11.7%) were satisfactory. The method quantification limit was 10 ng/g. The developed method was successfully applied for the determination of 4(5)-MI in fourteen commercial soy sauces from local markets. The results obtained in this work suggests that the method is suitable for the analysis of 4(5)-MI at low concentrations in high-salting and protein-containing soy sauce matrix.

Low molecule weight fucoidan mitigates atherosclerosis in ApoE (-/-) mouse model through activating multiple signal pathway

Atherosclerosis (AS) is a chronic inflammatory disease, and many factors are implicated in its progression. This work aims to study the preventive effects and the regulatory mechanism of low-molecular-weight fucoidan (LMWF), which is obtained from Saccharina japonica, on the development of AS. Serum biochemical indices and pathological analyses were determined via ELISA, hematoxylin and eosin (HE) and Oil Red O staining. These results indicated that LMWF ameliorated areas with atherosclerotic lesions and had a significant antioxidant effect. Anticoagulant assays showed that LMWF might serve as a potential anticoagulation drug for inhibiting the formation of atherothrombosis. Double immunofluorescence staining illustrated that LMWF inhibited both SMC proliferation and migration and macrophage formation and differentiation. A molecular biology experiment showed that LMWF exhibited an apparent regulatory effect on various signaling pathways. In conclusion, our results revealed that LMWF mitigated AS in the ApoE (-/-) mouse model by activating multiple signal pathways.

Gold Nanoparticle-DNA conjugates enhanced determination of dopamine by aptamer-based microcantilever array sensor

Aptamer-based microcantilever (ML) array sensor is a recently development method for the analysis of various molecules with free-label, high sensitivity and selectivity. Since its signal-transducing principle is the changes of surface stress or resonance frequency caused by molecules binding on the surface, there have difficulties in determining some low molecular weight substances. Herein, a novel detecting dopamine (DA) method based on aptamers functionalized-ML array using gold nanoparticle (NP)-DNA conjugates as the signal-amplifying strategy was developed. In this method, thiolated DA aptamers were self-assembled on the surface of ML array and then Au NP-DNA conjugates which contained a stretch of complementary sequences for DA aptamers were hybridized to DA aptamers. When DA sample interacted with its aptamer and replaced the Au NP-DNA conjugates, the surface stress of ML array was enhanced about fifteen times and resulted in much more deflection. The deflection was linearly proportional to DA concentration in the range from 0.5 to 4 μM with a lowest limit of detection 77.3 nM (R2 = 0.993). Some structural and functional DA analogues did not cause interference for the detection of DA. These results proved that the functionalized-ML array sensor based on Au NP-DNA conjugates could be used as a promising tool to detect low-weight molecules with high sensitivity and selectivity.

Hybrid complexes of high and low molecular weight hyaluronan delay in vitro replicative senescence of mesenchymal stromal cells: a pilot study for future therapeutic application.

Mesenchymal stem cells, a subpopulation of mesenchymal stromal cells (MSCs), are present in the stroma of several tissues. MSC in vitro cultivation for clinical treatments may greatly affect MSC properties. A primary handicap is replicative senescence that impairs MSC functions. Hyaluronan (HA) is present in the extracellular matrix that composes the stem cell niche environment and is under investigation as a key factor for in vitro stem cell growth. We evaluated the effect on MSC cultivation of HA hybrid cooperative complexes (HCC) that are obtained from high (H) and low (L) weight molecules (NAHYCO™). We compared this HCC with H-HA and L-HA. We investigated the effects of these HAs on proliferation, cell cycle, apoptosis, senescence, and differentiation following the addition of the polymer solutions in the culture media at concentrations that did not drastically modify the medium viscosity. Interestingly, 0,16% HCC significantly delayed the senescence compared with the controls. This occurred without alteration of the cell cycle, cytotoxicity, or apoptosis. HCCs also promoted adipogenic and chondrogenic differentiation. Our finding could suggest a potential functional role of HCC above the updated scientific reports of its effects and pave the way to optimization of MSC cultivation for therapeutic application.

The current and emerging sources of technical lignins and their applications.

Technical lignins are bulk feedstocks. They are generated as byproducts from pulping or cellulosic ethanol production. Since lignin undergoes significant structural changes in the chemical and physical treatments, all technical lignins are unique in terms of chemical structure, molecular weight, polydispersity, and impurity profile. Kraft lignin is potentially the largest source of technical lignin as new isolation technologies have been implemented on industrial scale in recent years. Lignosulfonate has been an integral product in sulfite pulping biorefinery. It has a well-established market in construction industry. Organosolv-like lignin production is increasing as cellulosic ethanol has been promoted as the substitute of fossil fuel. It may have unique applications because it has low molecule weight and is free from sulfur. Technical lignin application is expected to expand as the characteristics are improved with fractionation or chemical modification. The application of technical lignin has been focusing on developing products equivalent to those made by petroleum chemicals. The recent development in technical lignin supply should increase its market share as additives in polyurethanes and as the substitute of phenol-formaldehyde adhesives. Quality improvement of technical lignin may also encourage the study of lignin as an alternative feedstock for carbon fiber. In addition, technical lignin depolymerization has been extensively explored to provide renewable aromatic chemicals. Starting from controlled pyrolysis and thermal liquefaction as the baseline technologies, many different chemical depolymerization have been invented with a wide range of underlying chemical principles.

Characterization of dissolved organic matter and membrane fouling in coagulation-ultrafiltration process treating micro-polluted surface water

Coagulation–ultrafiltration (C–UF) is widely used for surface water treatment. With the removal of pollutants, the characteristics of organic matter change and affect the final treatment efficiency and the development of membrane fouling. In this study, we built a dynamic C–UF set-up to carry out the treatment of micro-polluted surface water, to investigate the characteristics of dissolved organic matter from different units. The influences of poly aluminum chloride and poly dimethyldiallylammonium chloride (PDMDAAC) on removal efficiency and membrane fouling were also investigated. Results showed that the dosage of PDMDAAC evidently increased the UV254 and dissolved organic carbon removal efficiencies, and thereby alleviated membrane fouling in the C–UF process. Most hydrophobic bases (HoB) and hydrophobic neutral fractions could be removed by coagulation. Similarly, UF was good at removing HoB compared to hydrophilic substances (HiS) and hydrophobic acid (HoA) fractions. HiS and HoA fractions with low molecule weight accumulated on the surface of the membrane, causing the increase of transmembrane pressure (TMP). Membrane fouling was mainly caused by a removable cake layer, and mechanical cleaning was an efficient way to decrease the TMP.

Performance Comparison of Commercial Enzymes for The Synthesis of Glucosamine by Chitosan Hydrolysis in The Presence of Surfactant

Glucosamine has attracted much attention due to its potential biological, pharmaceutical and nutritional effects. In this research, glucosamine was prepared by enzymatic hydrolysis of low molecule weight chitosan with nonionic surfactant (Tween 80) addition. The change in reducing sugar content was used as an indicator for the hydrolysis reaction rate. The results showed that addition of Tween 80 (1%, w/w) increases the formation of reducing sugars approximately two times higher than without Tween 80 addition. Hydrolysis using a combination of cellulase and β-glucosidase showed higher reaction rate than using a combination of cellobiohydrolase and β-glucosidase or using β-glucosidase only. The combination of cellulase and β-glucosidase showed optimum hydrolysis at reaction time of 24 hours. High-performance liquid chromatography (HPLC) analysis of the glucosamine product showed typical peak distributions the same as those of commercial standard glucosamine hydrochloride.

Clinical relevance of size selection of circulating DNA

Circulating cell-free DNA (cfDNA) is a non-invasive and powerful detection, diagnosis, prognosis, therapy response monitoring and recovery prediction tool, which opens new possibilities in fields of prenatal care, tumor therapy and transplant medicine. It is released from cells undergoing apoptosis and necrosis or by active secretion. Depending on the source and mechanisms of release, cfDNA is shed as fragments with different genetic and epigenetic profiles and in various lengths into the bloodstream. High- and low-weight cfDNA molecules can be detected in the different human body fluids. In pathological states, cfDNA size patterns have been found to vary from cfDNA released under healthy physiological conditions. In the following paragraphs, we describe methods and different technical platforms, to enrich, isolate and identify size profiles of cfDNA detected in human plasma and serum.

Effect of integrated pretreatment technologies on RO membrane fouling for treating textile secondary effluent: Laboratory and pilot-scale experiments

In this study, effect of pretreatment on reverse osmosis (RO) fouling was investigated for treating textile secondary effluent (SE), including coagulation, ultrafiltration (UF), magnetic ion exchange resin adsorption (MIEX) and their integrations. Laboratory-scale experiments exhibited that organics removal was highest by MIEX, followed by UF and coagulation; the integration of coagulation and MIEX was the most effective pretreatment to mitigate RO fouling. The effect of integrated pretreatment methods on RO fouling was also conducted in pilot-scale experiments. The same result with that of laboratory-scale experiments was obtained that coagulation+sand filter+MIEX as RO pretreatment was superior to coagulation+sand filter+UF. The results of gel permeation chromatograph (GPC) and excitation and emission matrix fluorescence (EEM) showed that the foulants on RO membrane were mainly composed of high molecule weight (MW) protein and soluble microbial products (SMP)-like matter. UF could remove the RO foulants effectively, but mitigation of RO fouling was at the expense of UF fouling. Besides, SEM shown that fouling layer on RO surface became more compact and peak heights of organics were higher on GPC spectra after UF pretreatment than MIEX likely due to the easily deposition of low MW organics in the valleys of RO membrane. Consequently, the integrated coagulation+MIEX was a promising pretreatment method prior to RO for treating textile SE.

Bioinspired butyrate-functionalized nanovehicles for targeted oral delivery of biomacromolecular drugs

Ligand-functionalization can increase the affinity of nanoparticles (NPs) with targeted cells. However, one major defect of ligands still exists in oral administration: limited receptor recognition. The hindrance of mucus network and deactivation of enzymes severely challenge the targeting efficiency of macromolecular ligands. Inspired by “molecular exchange” between intestinal microbiota and host cells, we anchored microbiota metabolite butyrate on classical “mucus-inert” polyethylene glycol (PEG) NPs. Butyrate has unique advantages of low molecule weight, high hydrophilicity and chemical stability. Interestingly, in vitro mucus-permeability and in vivo mucus distribution of PEG NPs were not impaired by butyrate-functionalization. Enhanced cellular uptake was achieved via specific interaction between butyrate and the monocarboxylate transporter (MCT) on cell membranes, which subsequently ameliorated transepithelial transport and intestinal absorption in the ileum. In vitro safety assessment validated the non-toxicity of butyrate-modification. Finally, insulin-loaded Bu-PEG NPs generated a stronger hypoglycemic response on diabetic rats and 2.87-fold higher oral bioavailability compared with bare PEG NPs. This study demonstrated that butyrate-functionalization could improve the intestinal absorption of macromolecules by overcoming multiple obstacles in the gastrointestinal tract, providing a promising active targeting strategy for oral administration.

Optical properties and spatial distribution of chromophoric dissolved organic matter (CDOM) in Poyang Lake, China

Abstract Chromophoric dissolved organic matter (CDOM) is a key component in aquatic ecosystem. CDOM plays a critical role in water optical attenuation and in biogeochemical processing. In this study the optical absorption properties and spatial distribution of CDOM were investigated during the wet season in Poyang Lake. Results showed that the absorption coefficients of CDOM varied significantly in four sections that contain different levels of turbidity. The absorption coefficients of CDOM in the section dominated by wetland water were higher than that in other sections. The study found that the absorption coefficients of CDOM were ranged from 1.59 to 4.71 m − 1 with an average value of 2.77 ± 0.76 m − 1 at 355 nm, and from 0.39 to 1.14 m − 1 with an average value of 0.70 ± 0.19 m − 1 at 440 nm, respectively. Spectral analysis with specific ultraviolet absorbance at 254 nm, absorption ratio between 250 and 365 nm and spectral slope indicated that CDOM in Poyang Lake was relatively high in molecule weight and aromaticity from terrestrial allochthonous inputs. Comparison of water samples revealed that CDOM in wetland contributed water had lower molecule weight and aromaticity influenced by autochthonous sources. Concentrations of dissolved organic carbon (DOC) and coefficients of CDOM absorption were significantly correlated at the range from 280 to 440 nm, especially at shorter wavelengths, which suggests that CDOM can be used as an effective DOC indicator in Poyang Lake. This study established a field-based knowledge for remote sensing measurements of CDOM in the largest fresh water lake in China.

Combined NMR structural characterization and thermogravimetric analyses for the assessment of the AAEM effect during lignocellulosic biomass pyrolysis

The goal of the present research is to study the effect of the inorganic species on the pyrolysis mechanism of lignocellulosic biomass. Many contradictions as the catalytic role of inorganic salts characterize the research works published up to now. These ambiguities are reasonably due to the morphological and structural modifications of the reacting biomass by the various demineralization and impregnation methods, that impact on the pyrolysis mechanism. In order to clarify the effect of inorganics on the pyrolysis mechanism, alkali and alkaline earth (AAEM) containing salts were deposited by impregnation method on cypress sawdust. Nuclear magnetic resonance analyses showed that the biomass structure was preserved and that metal deposition passes through a cationic exchange mechanism.The thermogravimetric analyses show that AAEMs have different effects by influencing the degradation behavior and the mass balances. In particular, potassium and sodium elements accelerated the hemicellulose thermal degradation without modifying the reaction mechanism. In addition, they showed a catalytic effect in the cellulose degradation towards low weight molecules decomposition and condensation reactions leading to the increase of the char yield. Contrary, the presence of magnesium and calcium seems to inhibit the hemicellulose thermal degradation without a significant effect on the cellulose degradation mechanism.

Preparation, Characterization and Prophylactic Study of New Microsphere Containing Doxycycline against Diseases of Shrimp

Therapeutically and prophylactically using Microspheres containing doxycycline isolated from shell of shrimp. Low molecule weight poly lactic acid was prepared. In this study, Poly lactic acid (PLA)/ poly vinyl alcohol (PVA)/poly ethyleneglycol(PEG) loading doxycycline blend solutions was prepared. Also Poly lactic acid (PLA)-Tannin blend via solvent evaporation method was prepared. Microspheres of chitosan/gelatin microsphere loading doxycycline was prepared by emulsion crosslinking technique. Both microsphere and blends were characterized by Fourier transform infrared (FTIR) spectrophotometer. The FTIR spectra were shown distinguish bands. The in vitro release of doxcycline from its matrix at pH 7 was studied. The prophylactic against white spot (Ich) disease of shrimp (Macrobrachium nipponense) was studied. The results were shown increase of percentage of survival of shrimp in both microsphere and blend compared with control. The highly percentage of survival was shown in the microsphere compare with blends.
 Key words: Chitosan, Microsphere, Polymer blend, Shrimp, Prophylactic.

Fast photoelectro-reduction of CrVI over MoS2@TiO2 nanotubes on Ti wire

A stable MoS2 nanosheets@TiO2 NTAs composite was prepared via a simple hydrothermal process. Few-layer MoS2 nanosheets distributed on the TiO2 nanotube top surface and the inner walls rather than filling in the tubes, allowing abundant tubular channels open to environment and benefiting for efficient mass transport. Photocatalytic (PE) and photoelectrocatalytic (PEC) performance of the composite were evaluated on CrVI reduction, with variable low molecule weight organic acids (LOAs) added as sacrificial electron donor to form a charge-transfer-complex (CTC) between LOAs and TiO2/MoS2, which is sensitive to the visible light illumination and could induce the photo-reduction of CrVI and photo-oxidation of LOAs. The overall trend of CrVI PEC rates are in the order as: L(+)-Tartaric acid>oxalic acid>citric acid>malic acid>amber acid, which is 103.9>62.5>31.2>21.6>2.5mg/Lmin−1cm−2, respectively. The improved catalytic performance and excellent stability of the composite can be attributed to the abundant active adsorption and reaction sites on MoS2 nanosheets and the formation of a heterojunction between TiO2 and MoS2. Moreover, the appropriate application of LOAs and voltage also have a great contribution to the utilization of sunlight and efficient separation of photogenerated carriers.

Nutrimetabolomics: An Update on Analytical Approaches to Investigate the Role of Plant-Based Foods and Their Bioactive Compounds in Non-Communicable Chronic Diseases.

Metabolomics is the study of low-weight molecules present in biological samples such as biofluids, tissue/cellular extracts, and culture media. Metabolomics research is increasing, and at the moment, it has several applications in the food science and nutrition fields. In the present review, we provide an update about the most frequently used methodologies and metabolomic platforms in these areas. Also, we discuss different metabolomic strategies regarding the discovery of new bioactive compounds (BACs) in plant-based foods. Furthermore, we review the existing literature related to the use of metabolomics to investigate the potential protective role of BACs in the prevention and treatment of non-communicable chronic diseases, namely cardiovascular disease, diabetes, and cancer.