Suberic Acid Acts as a Dissolving Agent as Well as a Crosslinker for Natural Polymers (Carbohydrate and Protein): A Detailed Discussion on the Chemistry Behind the Interaction

The natural polysaccharide chitosan and the natural protein collagen are widely used for the preparation of biopolymer materials in the presence of suitable crosslinkers. In this study, crosslinking feasibility of a dicarboxylic acid, namely suberic acid was tested using chitosan and collagen and in addition, thermal and mechanical properties were also tested for the resulting biopolymers. A 3D scaffold biopolymer material was prepared using chitosan at 1.0% (w/v) in the presence of suberic acid at 0.2% (w/v), similarly collagen 0.5% (w/v) in the presence of suberic acid 0.2% (w/v). Upon interaction, both the biopolymers displayed appreciable mechanical and thermal properties which add value to the biopolymers for biomedical applications. Molecular docking studies suggests the non-covalent interactions between the natural polymers and suberic acid is the reason behind the improved properties.     

Preparation and Characterization of Electroactive Biopolymers

Biopolymers have the potential for use as a matrix for applications such as controlled release devices, environmentally sensitive membranes, mimic materials and energetic applications. Renewable resources (such as starch) can be utilized as polymer matrices for electroactive materials that are sensitive to their environment. Natural polymers are generally more environmentally-friendly and biocompatible than existing synthetic products. Thermoplastic starch is naturally insulative; however, the chemical, electrical, and mechanical properties of the biopolymer matrix can be tailored for specific functionality in a continuous process utilizing reactive extrusion. Conductance can be measured in the solid state by a direct-current resistance method. Ion-conducting materials, produced by doping thermoplastic starch and biopolymers with metal halides, have 5 orders of magnitude greater conductance than native materials. There is a correlation between polymer mobility and conductance. Plant or microbial biopolymers with ionic functional groups have shown promise for higher levels of conductance. The conductance approaches the level of synthetic polymer electrolytes.     

Energy dispersive X-ray fluorescence analysis of marine pollution indicators

The present work shows a methodology for the application of EDXRF with a X-ray tube, in the analysis of elements in the following matrices: microalgae, marine algae, marine sediments and corals. Various methods were applied: one using a relative external standard, a fundamental parameters method, an absolute method based on elemental sensitivity, a method which used X-ray fluorescence excitation measured in the back side of the sample for low contents heavy elements determination and a TRXRF method. The thin layer samples were prepared using a plastic resin. The analyzed samples of marine algae, marine sediments and corals belong to a marine ecosystem from the North of Havana City, the most affected area by natural metereological phenomena and human impact.     

Biopolymers as a Flexible Resource for Nanochemistry

Biomass is an abundant source of chemically diverse macromolecules, including polysaccharides, polypeptides, and polyaromatics. Many of these biological polymers (biopolymers) are highly evolved for specific functions through optimized chain length, functionalization, and monomer sequence. As biopolymers are a chemical resource, much current effort is focused on the breakdown of these molecules into fuels or platform chemicals. However there is growing interest in using biopolymers directly to create functional materials. This Minireview uses recent examples to show how biopolymers are providing new directions in the synthesis of nanostructured materials.     

Collagen-Derived Biomaterials in Bone and Cartilage Repair

Summary: We have analyzed a number of collagen-derived biomaterials for the matrix- induced and assisted bone and cartilage tissue regeneration. These include the Small intestine submuosa (SIS) Restor ™, ACI-Maix collagen membrane, Chondro- Gide collagen membrane, Permacol collagen Ossix and lycoll collagen membrane and five types of collagen-based marine sponge skeletons. Certain characteristics of different scaffold materials with comparable chemical composition may vary significantly. This variation may have a relevant impact on the suitability of the scaffolds for bone and cartilage regeneration. It suggests that the ACI-Maix® membrane is the best available collagen-derived material for an MACI®/MACT® application. In addition, the study of marine sponge indicates that the collagenous fibre skeleton of marine sponges provides a suitable bioscaffold for bone regeneration, as it supports the adhesion, migration and proliferation of osteoblasts in vitro.     

疏水色谱法的进展及其在生化研究中的应用

着重评述了疏水色谱法的理论研究及疏水固定相中无机填料、有机填料、非多孔填料以及大孔膜的新发展,并对疏水色谱法在生物大分子的分离、纯化和生化研究中的应用,包括在蛋白质复性、折叠和分子构象变化等方面的应用作了介绍,全文包括６２篇文献和一张表格。     

Biopolymers from the Mauritian Marine Environment

To the best of our knowledge, the extraction of biopolymers from algae and seaweeds still remains untapped. Prior studies in this area have been limited to a taxonomic survey of algae and seaweeds found around our coastal regions. In this paper, we report on the extraction of biopolymers from Hypnea, Eucheuma and Gracilaria species collected around the coastal regions of Mauritius. Various extraction conditions were used and their effects on yield and structure of the corresponding biopolymers were investigated. The extracted polysaccharides were characterized by a combination of IR, NMR, SEC, viscometry and elemental analyses. These revealed that polysaccharide extracted from Gracilaria is a highly methylated agar and Hypnea/Eucheuma contain κ-carrageenan.     

Liquid crystal templating of nanomaterials with nature's toolbox

Naturally occurring biomolecules are sustainable and green precursors for the development of new materials. Within this family of natural materials, cellulose nanocrystals (CNCs) have emerged as one of the most promising materials because of their outstanding physico-chemical properties and the possibility to produce them in large quantities. One key trait of CNCs is their ability to self-assemble into a chiral nematic liquid crystalline phase. In this review, we discuss how templating can be used to transfer the three-dimensional structure of liquid crystalline CNC phases onto solid materials. This is followed by examples that illustrate the fascinating properties and potential applications that arise from the resulting nanostructured materials such as sensing and catalysis. We then summarize efforts to use the liquid crystalline phase of a selection of other biopolymers for templating. While nanocrystalline chitin, having very similar properties to CNCs, has been successfully employed to make a variety of new materials, efforts to template liquid crystal phases of other biomolecules have been met with limited success. However, we discuss virus nanoparticles and collagen as examples to highlight further possibilities for materials research.     

IAEA reference materials for quality assurance of marine radioactivity measurements

The IAEA's Marine Environment Laboratory has been assisting laboratories in Analytical Quality Control Services (AQCS) for the analysis of radionuclides in the marine environment since the early seventies. AQCS through world-wide and regional intercomparison exercises and the provision of reference methods and reference materials (RM) have been recognized as an important component of quality assurance/quality control. A total of 43 intercomparison exercises were organized and 37 RM were produced for marine radioactivity studies. All important marine matrices were covered, e.g., seawater, marine sediments of different chemical compositions, fish, shellfish and seaplants. RM were prepared from samples collected at contaminated sites (e.g., the Irish Sea, the Baltic Sea, the Arabian Sea, Mururoa and Bikini Atolls, etc.) as well as from sites affected only by global fallout (e.g., the Pacific Ocean). Available RM are listed in the IAEA biennial catalogue and can be purchased at a minimal price. An overview of prepared RM for radionuclides in marine matrices is presented and discussed in more detail.     

Biopolymers for surface engineering of paper-based products

The combination of biopolymer science and technology with surface engineering of paper-based cellulosic materials has a lot of potential in stepping forward to a sustainable future. Various biopolymers such as oxidized starch, carboxymethyl cellulose, and polylatic acid have been commercially used to engineer paper surface. The paper-based cellulosic products are widely used for printing/writing and packaging applications. However, the production of these products are currently dependent mainly upon the use of petroleum-based materials including synthetic pigment coating latexes and barrier coating materials. The major challenges associated with some biopolymers are their relatively high costs and unsatisfactory performances. Continuing efforts are being made to enable the increased and value-added use of various biopolymers in paper surface engineering. These polymers can be based on cellulose, hemicelluloses, chitosan, alginate, protein, polylactic acid, and polyhydroxyalkanoate. The biopolymer-engineered paper products can be tailored for use as substitutes for various non-renewable materials including plastics and metals as well. Future development in the area of biopolymers for paper surface engineering is likely to lead to new possibilities and breakthroughs, paving the way for a substantially sustainable and green future.     

Determination of 11 low-molecular-weight carbonyl compounds in marine algae by high-performance liquid chromatography

A new analytical method is reported for the determination of 11 volatile carbonyl compounds isolated at room temperature from the headspace of marine algae. This method is based on the conversion of the carbonyl compounds to their 2,4-dinitrophenylhydrazone derivatives followed by high-performance liquid chromatography analysis. Using this method, 11 carbonyl compounds are detected and identified from the dynamic headspace sampling of 10 species of marine algae. Eight compounds are quantitated and the three remaining are only identified. Under optimized conditions, all carbonyl compounds are separated in 32 min. The detection and quantitation limits of the high-performance liquid chromatography method are, respectively, in the range of 0.26-0.85 ng/g of algae (formaldehyde) to 13.77-45.90 ng/g of algae (E)-2-hexenal. The calibration curves are linear in the concentration range of 2.0-1000 microg/L of solution, corresponding to 0.34-170.00 ng/g of algae. Acetaldehyde and propanal are the most abundant carbonyl compounds identified, with concentrations as high as 980 and 790 ng/g, respectively. The present work, as far as we know, is the first analytical methodology that has been developed to determine low-molecular-weight carbonyl compounds in marine algae. Because many species of marine algae are used as human food, the reported method should be useful to investigators studying the nutritional value as well as oxidative spoilage of fresh and preserved marine algae that is destined for human consumption.     

An overview of laboratory performance studies conducted by the IAEA for marine pollution studies of metals and organic contaminants

Aspects of the International Atomic Energy Agency (IAEA) Analytical Quality Control Services (AQCS) for marine environmental studies are discussed, focusing on recent laboratory performance studies (LPS) and the production of reference materials for trace metals and organic compounds in various marine matrices. The IAEA has organized seventeen global interlaboratory studies for a range of organic contaminants. Of note has been the inclusion of numerous polychlorinated biphenyl congeners (PCBs) and some sterols of anthropogenic origin. Concurrently, there have been eleven worldwide intercomparison exercises for trace metals in the marine environment, most of which included methylmercury. Although such interlaboratory studies can help improve performance in individual laboratories and regional laboratory networks, the results reveal that problems remain in the determination of some metals and many organic contaminants.     

Antimicrobial activity of collagen material with thymol addition for potential application as wound dressing

Recently, special attention has been paid to the development of active wound dressing materials based on biopolymers. Collagen is a natural polymer, which meets the requirements of modern materials for medical applications. However, despite its unique properties, collagen has no antimicrobial activity. In this work thymol was incorporated into collagen films to meet antimicrobial properties of the material. Thymol is a naturally occurring phenolic compound recognized as an antimicrobial agent. Collagen/thymol thin films were obtained through solvent evaporation using collagen solutions containing different amounts of thymol. The structure of the obtained materials was studied using FTIR-ATR spectroscopy. The inhibition ability on the growth of several strains of microorganisms was tested. The standard ISO 22196:2007 was used to define the bactericidal properties of the material. The growth of the following bacteria on the collagen/thymol films was studied: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Enterobacter aerogenes, Candida albicans. The results showed that the growth of Staphylococcus aureus was the most inhibited compared to the other tested strains. Collagen/thymol material is more efficient against pathogens through direct contact compared to the diffusion of thymol from the material. In general, the thymol addition inhibits biofilm formation on the collagen surface.     

Benefits of high resolution IC-ICP-MS for the routine analysis of inorganic and organic arsenic species in food products of marine and terrestrial origin

A recently developed and validated method for simultaneous determination of 17 inorganic and organic arsenic compounds in marine biota has been successfully applied to routine analysis of different food products, including fish, shellfish, edible algae, rice, and other types of grain. During one year, approximately 250 food samples were analyzed, mostly fish and rice. Long-term stability and robustness of the system was observed and reproducible results for certified reference materials were ensured by means of control charts. The separation was performed by ion-pair chromatography on an anion-exchange column to separate anionic, neutral, and cationic arsenic species in one chromatographic run. Hyphenation to ICP–MS allowed element-specific and sensitive detection of the different arsenic species with a detection limit as low as 8 ng As L^–1 in the sample extract, which is equivalent to 2 ng As g^–1 in the original sample. Special emphasis was laid on the analysis of marine algae and rice samples. These food types can contain elevated levels of the very toxic inorganic arsenic species (up to 90% in rice) and therefore are the focus of interest in the food industry. In marine algae, inorganic arsenic was mainly present as arsenate whereas in rice arsenite predominated.     

Facile Synthesis and Characterization of Quercetin-Loaded Alginate Nanoparticles for Enhanced In Vitro Anticancer Effect Against Human Leukemic Cancer U937 Cells

Journal of Cluster Science - Nanoparticles synthesized from biopolymers have received attention for their use as biological carriers in the delivery of hydrophobic drugs. Alginate, a marine...     

Simultaneous screening of homotaurine and taurine in marine macro-algae using liquid chromatography–fluorescence detection

Simultaneous analysis of homotaurine and its homologous, taurine, is a highly challenging issue, especially in matrices they exist simultaneously. A simple precolumn derivatization procedure combined with high-performance liquid chromatography–fluorescence detection was developed for simultaneous determination of homotaurine and taurine in marine macro-algae. The analytes were derivated with o-phthalaldehyde at an ambient temperature and alkaline medium. Calibration curves were linear in the ranges of 50–2500 µg L^?1 for homotaurine and 100–2500 µg L^?1 for taurine with the coefficients of determination higher than 0.998. Limits of detection of homotaurine and taurine were 15 and 30 µg L^?1, respectively. Intraday (n = 6) and inter-day (n = 4) precisions of the method were satisfactory with relative standard deviations less than 6.0%. Good recoveries (>94%) were acquired by the method for extraction of homotaurine and taurine from algae matrices. Liquid chromatography–mass spectrometry was also used to confirm detection of the analytes in algae samples. The data suggest that the method was successfully applied to simultaneous determination of homotaurine and taurine in algae samples.     

Preparation and characterization of collagen/chitosan poly (ethylene glycol)/nanohydroxyapatite composite scaffolds

Porous three‐dimensional collagen/chitosan scaffolds combined with poly (ethylene glycol) (PEG) and hydroxyapatite were obtained through a freeze‐drying method. Physical cross‐linking was examined by dehydrothermal treatment. The prepared materials were characterized by different analyses, eg, scanning electron microscopy (SEM), measurements of porosity and swelling, mechanical properties, and resistance to enzymatic degradation. The porosity of scaffolds and their swelling ratio decreased with the addition of hydroxyapatite. Moreover, after exposure to collagenase, the collagen/chitosan matrices containing PEG showed much faster degradation rate than matrices with the addition of hydroxyapatite. The results indicated that the addition of hydroxyapatite led to improvement of stiffness. The highest degree of porosity and swelling were demonstrated by collagen/chitosan/PEG matrices without hydroxyapatite.     

AGRO-MATERIALS: A BIBLIOGRAPHIC REVIEW

ABSTRACT

Facing the problems of plastic recycling and fossil resources exhaustion, the use of biomass to conceive new materials appears like a reasonable solution. Two axes of research are nowadays developed: on the one hand the synthesis of biodegradable plastics, whichever the methods may be, and on the other hand the utilization of raw biopolymers, which is the object of this article. From this perspective, the “plastic” properties of natural polymers, the characteristics of the different classes of polymers, the use of charge in vegetable matrices, and the possible means of improving the durability of these agro-materials are reviewed.     

Fit-for-purpose shellfish reference materials for internal and external quality control in the analysis of phycotoxins

The need for reference materials for quality control of analysis of foodstuffs has been stressed frequently. This has been particularly true in the phycotoxins field, where there is a great shortage of both pure calibration standards and reference materials. Worldwide there are very few independent bodies that produce certified reference materials for phycotoxins, the main producers currently being the National Research Council Canada and the Japanese Food Research Laboratory. Limited availability of contaminated shellfish and algae, as well as the time and knowledge necessary for the production of adequate reference materials, continuously lead to limited editions of certified reference materials and even more limited production of in-house reference materials. The restricted availability of in-house quality control materials promotes the rapid use of the limited certified reference materials, which in turn hampers the production of the suite of materials required globally for complete protection of public health. This paper outlines the various options that analysts can pursue in the use of reference materials for internal and external quality control, with a view to optimising the efforts of both reference materials users and reference materials producers. For this purpose, the logical sequence is reviewed from the discovery of a new bioactive compound in shellfish, through initial method development up to regulation for food safety purposes including accepted reference methods. Subsequently, the requirements for and efforts typically spent in the production and characterisation of laboratory reference materials, certified reference materials and other test materials used in inter-laboratory studies or proficiency testing, in the area of marine biotoxins are evaluated. Particular emphasis is put on practical advice for the preparation of in-house reference materials. The intricate link between reference material characterisation and method performance is outlined to give guidance on the appropriate in-house method validation in the rapidly developing field of phycotoxins.      

Biopolymer based nanomaterials in drug delivery systems: A review

Drug delivery systems (DDS) are used to achieve a higher therapeutic effects of a pharmaceutical drug or natural compound in a specific diseased site with minimal toxicological effect and these systems consists of liposomes, microspheres, gels, prodrugs and many. Nanotechnology is a rapidly developing multi-disciplinary science that ensures the fabrication of the polymers to nanometer scale for various medical applications. Uses of biopolymers in DDS ensure the biocompatibility, biodegradability and low immunogenicity over the synthetic ones. Biopolymers such as silk fibroins, collagen, gelatin, albumin, starch, cellulose and chitosan can be easily made into suspension that serve as delivery vehicles for both macro and mini drug molecules. There are various methods such as supercritical fluid extraction, desolvation, electrospraying, spray-drying, layer-by-layer self-assembly, freeze-drying and microemulsion introduced to make these DDS. This drug carrier systems enhance the drug delivery actively and can be used in ocular, transdermal, dental or intranasal delivery systems. This review describes the new trends in nanomaterials based drug delivery systems mainly using biopolymers such as proteins (silk fibroin, collagen, gelatin and albumin) and polysaccharides (chitosan, alginate, cellulose and starch).