New Type Of Biomaterial Research Articles

Strong and antistatic biomass adhesive for wood-based composites with electrostatic discharge protection function

Soybean protein adhesive, as an aldehyde-free biomass adhesive, has gained significant attention as an environmentally friendly material in recent years. It not only aligns with the objectives of the double carbon strategy but also contributes to the environmental protection strategy of reducing carbon emissions. And the functional modification of soybean protein adhesive and its wood composite hold great importance in expanding its application domains and meeting specialized requirements. This research focused on developing a robust, antistatic adhesive derived from soy protein as an alternative to formaldehyde-based resins, which represents a critical path in the advancement of wood-based composites that are free from formaldehyde and possess functional properties. However, ensuring the bonding strength of soy protein adhesive while developing antistatic adhesives and their wood-based composite materials is of great research value and challenge. Inspired by the organic-inorganic hybrid structure, this study aimed to prepare a strong and durable soy protein adhesive with excellent mechanical strength and multifunctionality by using a self-synthesized crosslinking agent called AP and the loaded two-dimensional MXene, which was stabilized in a dispersion of nanocellulose (CNC). The dry and wet shear strength of the resulting adhesive increased by 103.8 % and 113.8 % to 2.21 MPa and 1.24 MPa, indicating the stable crosslinking structure formed in adhesive system by the covalent bond between self-synthesized crosslinking agent AP and the carboxyl groups on proteins, as well as the hydrogen bond interactions between C-M and the proteins. Furthermore, the adhesive exhibited significant antistatic and self-extinguishing properties, with the particleboard modified by adhesive SPI/C-M/AP having a resistivity of 9.212 × 1011 Ω cm. The resistivity decreased with increasing MXene content, providing potential applications for places such as school computer rooms and factory electronic equipment rooms. This breakthrough in multifunctional biomass-based adhesives and composite materials enriches the preparation of new types of biomaterials with antistatic and flame retardant properties.

Flax pomace as a substitute for wood raw material in lignocellulosiccomposite technology

Flax pomace as a substitute for wood raw material in lignocellulosic composite technology. In the present study, composites made from flax seed pomace and PE, PP, PLA and modified starch were subjected quality parameter tests. Density, modulus of rapture (MOR), and modulus of elasticity (MOE) were examined, as well as water absorption and swelling to thickness after 2h and 24 h soaking in water, wettability and surface roughness. Addition of flax to different polymers caused significant changes of parameters but the level of influence of the addition varied between polymers. Although the characteristics of the produced biocomposites have been shown to be in general inferior to pure polymers, efforts should be made to improve these characteristics. Agri-food waste products can be a valuable raw material for the production of new type of biomaterials

Mechanistic Insights into Hyaluronic Acid Induced Peptide Nanofiber Organization in Supramolecular Hydrogels.

Composite hydrogels composed of low-molecular-weight peptide self-assemblies and polysaccharides are gaining great interest as new types of biomaterials. Interactions between polysaccharides and peptide self-assemblies are well reported, but a molecular picture of their impact on the resulting material is still missing. Using the phosphorylated tripeptide precursor Fmoc-FFpY (Fmoc, fluorenylmethyloxycarbonyl; F, phenylalanine; Y, tyrosine; p, phosphate group), we investigated how hyaluronic acid (HA) influences the enzyme-assisted self-assembly of Fmoc-FFY generated in situ in the presence of alkaline phosphatase (AP). In the absence of HA, Fmoc-FFY peptides are known to self-assemble in nanometer thick and micrometer long fibers. The presence of HA leads to the spontaneous formation of bundles of several micrometers thickness. Using fluorescence recovery after photobleaching (FRAP), we find that in the bundles both (i) HA colocalizes with the peptide self-assemblies and (ii) its presence in the bundles is highly dynamic. The attractive interaction between negatively charged peptide fibers and negatively charged HA chains is explained through molecular dynamic simulations that show the existence of hydrogen bonds. Whereas the Fmoc-FFY peptide self-assembly itself is not affected by the presence of HA, this polysaccharide organizes the peptide nanofibers in a nematic phase visible by small-angle X-ray scattering (SAXS). The mean distance d between the nanofibers decreases by increasing the HA concentration c, but remains always larger than the diameter of the peptide nanofibers, indicating that they do not interact directly with each other. At a high enough HA concentration, the nematic organization transforms into an ordered 2D hexagonal columnar phase with a nanofiber distance d of 117 Å. Depletion interaction generated by the polysaccharides can explain the experimental power law variation and is responsible for the bundle formation and organization. Such behavior is thus suggested for the first time on nano-objects using polymers partially adsorbing on self-assembled peptide nanofibers.

Protein-macrocycle polymorphism: crystal form IV of the Ralstonia solanacearum lectin-sulfonato-calix[8]arene complex.

Controlled protein assembly and crystallization is necessary as a means of generating diffraction-quality crystals as well as providing a basis for new types of biomaterials. Water-soluble calixarenes are useful mediators of protein crystallization. Recently, it was demonstrated that Ralstonia solanacearum lectin (RSL) co-crystallizes with anionic sulfonato-calix[8]arene (sclx8) in three space groups. Two of these co-crystals only grow at pH ≤ 4 where the protein is cationic, and the crystal packing is dominated by the calixarene. This paper describes a fourth RSL-sclx8 co-crystal, which was discovered while working with a cation-enriched mutant. Crystal form IV grows at high ionic strength in the pH range 5-6. While possessing some features in common with the previous forms, the new structure reveals alternative calixarene binding modes. The occurrence of C2-symmetric assemblies, with the calixarene at special positions, appears to be an important result for framework fabrication. Questions arise regarding crystal screening and exhaustive searching for polymorphs.

Three-dimensional scaffolds for bioengineering of cartilage tissue

The cartilage tissue is neither supplied with blood nor innervated, so it cannot heal by itself. Thus, its reconstruction is highly challenging and requires external support. Cartilage diseases are becoming more common due to the aging population and obesity. Among young people, it is usually a post-traumatic complication. Slight cartilage damage leads to the spontaneous formation of fibrous tissue, not resistant to abrasion and stress, resulting in cartilage degradation and the progression of the disease. For these reasons, cartilage regeneration requires further research, including use of new type of biomaterials for scaffolds. This paper shows cartilage characteristics within its most frequent problems and treatment strategies, including a promising method that combines scaffolds and human cells. Structure and material requirements, manufacturing methods, and commercially available scaffolds were described. Also, the comparison of poly(L-lactide) (PLLA) and polyethersulfone (PES) 3D membranes obtained by a phase inversion method using nonwovens as a pore-forming additives were reported. The scaffolds' structure and the growth ability of human chondrocytes were compared. Scaffolds' structure, cells morphology, and protein presence in the membranes were examined with a scanning electron microscope. The metabolic activity of cells was tested with the MTT assay. The structure of the scaffolds and the growth capacity of human chondrocytes were compared. Obtained results showed higher cell activity and protein content for PES scaffolds than for PLLA. The PES membrane had better mechanical properties (e.g. ripping), greater chondrocytes proliferation, and thus a better secretion of proteins which build up the cartilage structure.

Tuning properties of bio-rubbers and its nanocomposites with addition of succinic acid and ɛ-caprolactone monomers to poly(glycerol sebacic acid) as main platform for application in tissue engineering

In this research new types of biomaterials have been introduced. They are based on glycerin, sebacic acid, succinic acid and ɛ-caprolactone as their monomers. Their bio-nanocomposites were prepared with organo-montmorillonite (Cloisite 30B, C30B) and nano-hydroxyapatite (n-HA) by in-situ polymerization technique. Chemical, mechanical and biologocal properties of prepared samples were assessed by different tests. 1H NMR study showed that resin of polymeric chains poly(glycerol-sebacic) (PGSe), poly(glycerol-Sebacic-succinic) (PGSeSu) and Poly(glycerol-sebacic-succinic)-co-polycaprolactone (PGSeSuPC) were successfully synthesized. The results of dynamic contact angle test were showed that the presence of succinic acid and ɛ-caprolactone monomers in PGSe would provide attractive characteristics and the existence of nanoparticles would enhance the hydrophilicity of the samples. According to Dynamic mechanical thermal analysis (DMTA), it was determined that the storage modulus of samples which have been co-polymered by succinic acid and ɛ-caprolactone is higher than that of the PGSe at −40 °C and it is lower in higher temperatures. The existence of succinic acid and ɛ-caprolactone monomers have had softening effects on movement of PGSe chains. In tan(δ) behavior, the glass transformation temperature (Tg) for PGSe is about –7.6 °C and by co-polymerization with succinic acid and ɛ-caprolactone it changed to −11.8 °C and −26 °C respectively. Mechanical analysis on normal and degraded samples were done and their results showed that the presence of e-caprolactone into the bio-rubber’s backbone, has had significant effects on Young’s modulus and tensile strength. However, cyclic tensile test showed that hysteresis and residual strain of PGSeSuPC-C3 sample was higher than other samples. Hydrocatalytic degradation test explained that the existence of succinic acid monomer as an absorbent of water molecules, have enhanced the degradability, while the combination of nanoparticles of C30B and n-HA have had a positive influence on samples degradation.

Cancer Cell Preferential Penetration and pH-Responsive Drug Delivery of Oligorutin.

We report herein a novel delivery system, derived from the facile enzymatic synthesis of oligorutin (OR), for cancer cell targeting and pH-responsive drug delivery. In this study, we demonstrate that OR could preferentially penetrate cancer cells via the lipid raft-mediated endocytosis pathway, and cell membrane cholesterol was critical to the internalization of OR. The accumulation of OR in the tumor region was further confirmed by an in vivo biodistribution study. Considering the tumor-targeting property of OR, a pH-responsive drug delivery system (OR-BTZ) was developed by covalent conjugation of the catechol groups on OR with antitumor drug bortezomib (BTZ) through a pH-sensitive borate ester bond. OR-BTZ exerted cytotoxicity as well as inhibition of the migration and invasion to hepatoma carcinoma cells and showed no apparent cytotoxicity with liver normal cells. The OR-BTZs also presented significant therapeutic efficacy and low systematic toxicity in the murine hepatocellular carcinoma model. To our knowledge, this study presents the first attempt to exploit the potential of oligoflavonoids for cancer cell-targeted drug delivery and will motivate the development of flavonoids and their derivatives as a new type of biomaterials for tumor-targeted therapy.

A Mechanics Study on the Self-Righting of Abalone from the Substrate.

In this study, we aim to probe the self-righting behavior of abalone on a substrate based on experiments and mechanistic analyses. A successful self-righting process of abalone is observed, and its critical condition in theory can be given in terms of the rotation angle. Then, according to the moment balance and potential energy minimization, the required tension force of the abalone foot for self-righting is derived with respect to the rotation angle. The experimental result also shows that in many cases the abalone cannot finish this self-righting process. Then, measurements on the tolerant strength of abalone muscle and tolerant adhesion strength of the foot on substrate are both conducted. It is judged that the abalone muscle is strong enough, which can provide enough tension force, and thus, the self-righting mainly depends on the adhesion area of the foot on substrate. These findings cast new light on engineering new types of biomaterials and devices, such as marine equipment and soft robotics.

Enzyme-instructed self-assembly of the stereoisomers of pentapeptides to form biocompatible supramolecular hydrogels

This article reports enzyme-instructed self-assembly (EISA) of stereoisomers of pentapeptides as a simple approach for generating biocompatible supramolecular hydrogels as potential soft bionanomaterials. Peptide-based supramolecular hydrogels are emerging as a new type of biomaterials. The use of tyrosine phosphate offers a trigger for enzymatic hydrogelation, and the incorporation of D-amino acids can increase the proteolytic stability of peptides. This work compared four phosphorpeptides that are stereoisomers in terms of rate of dephosphorylation, proteolytic stability, and cell compatibility. The results show that the naphthyl (Nap)-capped pentapeptides, containing the amino acid sequence of Phe-Phe-Gly-Glu-pTyr, are able to undergo EISA to form the hydrogels consisting the nanofibres of the dephosphorylated pentapeptides. The naphthyl-capped D-phosphopentpeptides, contrasting to a naphthyl-capped D-phosphotripeptide (Nap-D-Phe-D-Phe-D-pTyr), are largely cell compatible. This result, suggesting that the sequence of phophopeptides also dedicates the cell compatibility of the peptide assemblies resulted from EISA, provides useful insights for developing supramolecular hydrogels as potential biomaterials with tailored properties.

Valproic acid-labeled chitosan nanoparticles promote recovery of neuronal injury after spinal cord injury

Chitosan nanoparticles have been recognized as a new type of biomaterials for treatment of spinal cord injury (SCI). To develop a novel treatment method targeted delivery injured spinal cord, valproic acid labeled chitosan nanoparticles (VA-CN) were constructed and evaluated in the treatment of SCI. Our results demonstrated that administration of VA-CN significantly promoted the recovery of the function and tissue repair after SCI. Moreover, we found treatment of VA-CN inhibited the reactive astrocytes after SCI. Furthermore, administration of VA-CN enhanced immunoreactions of neuronal related marker NF160, which suggested that VA-CN could promote the neuroprotective function in rats of SCI. The production of IL-1β, IL-6 and TNF-α were significantly decreased following treatment of VA-CN. Meanwhile, administration of VA-CN effectively improved the blood spinal cord barrier (BSCB) disruption after SCI. Administration of VA-CN could enhance the recovery of neuronal injury, suppress the reactive astrocytes and inflammation, and improve the blood spinal cord barrier disruption after SCI in rats. These results provided a novel and promising therapeutic manner for SCI.

Thin films deposition on 304L stainless steel using e-gun technology for medical applications

The purpose of this article is to characterize surface of 304L stainless steel coating by e-gun technology with thin films of Ta2O5 and ZnO. ZnO films are used in pharmaceutical industries, in cosmetics and in medicine, grace of their better anticorrosive, antibacterial and photo catalytic properties. Ta2O5 films have rapidly evolved in medicine research with the promise of development of new types of biomaterials used in medicine. Ta2O5 coatings present an excellent biocompatibility, good dielectric properties, and high corrosion resistance. The biomaterials are realized by novel and special methods to resist of the biological reactions that occur in medical implants (protein adsorption, cell adhesion, cell growth, blood compatibility, etc.). The most important surface properties are physical properties, durability and biocompatibility. The physical properties of a biomaterial that must to be measure, are mechanical strength, permeability and elasticity. Biocompatibility is the response of the biomaterial or of the device to the proteins, cells and organisms action, when the implants are in contact with the biological tissue. The common method to characterize biomaterial surfaces are: contact angles, ESCA (XPS), Auger Electron Spectroscopy, SIMS, FTIR-ATR, STM, SEM and EDAX.

Functionalized genetic engineered silk-based biomaterials and their applications

Silk-based biomaterials are featured with excellent mechanical properties, good biocompatibility and biodegradability, which contribute to their potential applications in biomedical field. The current recognition of silk protein materials in structure and function provides a basic theory for the transformation of silk protein into new types of biomaterials. In addition, exogenous sequences encoding new peptide or structural domain can be inserted into the maternal gene sequences encoding silk proteins through genetic engineering technology to synthesize novel silk-based biomaterials with unique functions. This review summarizes the current trend and development perspective of genetically engineered functional silk-based materials for biomedical applications.

Ultrashort peptides: minimum number in amino acid residues, maximum number in bioapplications.

Ultra-short peptides are an intrigue new type of biomaterials for various bioapplications. Over the decades, peptides have evolved as biomaterials due to the ease of synthesis, ease of scaling up, feasibility to be functionalized/modified, and recognition by biological system1. Peptide-based hydrogels are widely used as scaffolds for encapsulation and delivery of drugs, genes and cells. They are made of natural amino acids. Thus they are non-immunogenic. They contain carboxylic and amine groups. Thus they can be easily functionalized with bioactive moieties. However, for peptides with more than 16 amino acid residues, they are expensive due to the high synthesis cost. As such, ultra-short peptides with only 2 to 7 amino acid residues stand out due to their easy and cost-effective synthesis, facile assembly in aqueous solution, biocompatibility and mechanical stability. These ultrashort peptides can form hydrogels without the addition of enzymes or other types of cross-linkers.

Characterization of clinically relevant model bacterial strains of Pseudomonas aeruginosa for anti-biofilm testing of materials

There is a great interest in developing novel anti-biofilm materials in order to decrease medical device-associated bacterial infections causing morbidity and high healthcare costs. However, the testing of novel materials is often done using bacterial lab strains that may not exhibit the same phenotype as clinically relevant strains infecting medical devices. Furthermore, no consensus of strain selection exists in the field, making results very difficult to compare between studies. In this work, 19 clinical isolates of Pseudomonas aeruginosa originating from intubated patients in an intensive care unit have been characterized and compared to the lab reference strain PAO1 and a rmlC lipopolysaccharide mutant of PAO1. The adhesion and biofilm formation was monitored, as well as cell properties such as hydrophobicity, zeta potential and motility. Two groups of isolates were observed: one with high adhesion to polymer surfaces and one with low adhesion (the latter including PAO1). Furthermore, detailed biofilm assays in a flow system were performed using five characteristic isolates from the two groups. Confocal microscopy showed that the adhesion and biofilm formation of four of these five strains could be reduced dramatically on zwitterionic surface coatings. However, one isolate with pronounced swarming colonized and formed biofilm also on the antifouling surface. We demonstrate that the biofilm properties of clinical isolates can differ greatly from that of a standard lab strain and propose two clinical model strains for testing of materials designed for prevention of biofilm formation in the respiratory tract. The methodology used could beneficially be applied for screening of other collections of pathogens to identify suitable model strains for in vitro biofilm testing. Statement of SignificanceMedical-device associated infections present a great challenge in health care. Therefore, much research is undertaken to prevent bacterial colonization of new types of biomaterials. The work described here characterizes, tests and presents a number of clinically relevant bacterial model strains for assessing biofilm formation by Pseudomonas aeruginosa. Such model strains are of importance as they may provide better predictability of lab testing protocols with respect to how well materials would perform in an infection situation in a patient. Furthermore, this study uses the strains to test the performance of polymer surfaces designed to repel bacterial adhesion and it is shown that the biofilm formation for four out of the five tested bacterial strains was reduced.

Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coatings on biodegradable AZ31 magnesium alloy.

In this work, a magnesium phytic acid/hydroxyapatite composite coating was successfully prepared on AZ31 magnesium alloy substrate by chemical conversion deposition technology with the aim of improving its corrosion resistance and bioactivity. The influence of hydroxyapatite (HA) content on the microstructure and corrosion resistance of the coatings was investigated. The results showed that with the increase of HA content in phytic acid solution, the cracks on the surface of the coatings gradually reduced, which subsequently improved the corrosion resistance of these coated magnesium alloy. Electrochemical measurements in simulated body fluid (SBF) revealed that the composite coating with 45 wt.% HA addition exhibited superior surface integrity and significantly improved corrosion resistance compared with the single phytic acid conversion coating. The results of the immersion test in SBF showed that the composite coating could provide more effective protection for magnesium alloy substrate than that of the single phytic acid coating and showed good bioactivity. Magnesium phytic acid/hydroxyapatite composite, with the desired bioactivity, can be synthesized through chemical conversion deposition technology as protective coatings for surface modification of the biodegradable magnesium alloy implants. The design idea of the new type of biomaterial is belong to the concept of "third generation biomaterial". Corrosion behavior and bioactivity of coated magnesium alloy are the key issues during implantation. In this study, preparation and corrosion behavior of magnesium phytic acid/hydroxyapatite composite coatings on magnesium alloy were studied. The basic findings and significance of this paper are as follows: 1. A novel environmentally friendly, homogenous and crack-free magnesium phytic acid/hydroxyapatite composite coating was fabricated on AZ31 magnesium alloy via chemical conversion deposition technology with the aim of enhancing its corrosion resistance and bioactivity. The chemical conversion coatings, which are formed through the reaction between the substrate and the environment, have attracted increasing attention owing to the relative low treatment temperature, favorable bonding to substrate and simple implementation process. 2. With the increasing of hydroxyapatite (HA) content, the crack width in the composite coatings and the thickness of the coatings exhibit obviously decreased. The reason is probably that when adding HA into the phytic acid solution, the amount of active hydroxyl groups in the phytic acid are reduced via forming the coordination bond between P-OH groups from phytic acid and P-OH groups from the surface of HA, thus decreasing the coating thickness and hydrogen formation, as well as avoiding coating cracking. 3. By adjusting the HA content to 45 wt.%, a dense and relatively smooth composite coating with ~1.4 μm thickness is obtained on magnesium alloy, and exhibits high corrosion resistance and good bioactivity when compared with the single phytic acid conversion coating.

Electroconductive natural polymer-based hydrogels.

Hydrogels prepared from natural polymers have received immense considerations over the past decade due to their safe nature, biocompatibility, hydrophilic properties, and biodegradable nature. More recently, when treated with electroactive materials, these hydrogels were endowed with high electrical conductivity, electrochemical redox properties, and electromechanical properties; consequently, forming a smart hydrogel. The biological properties of these smart hydrogels, classified as electroconductive hydrogels, can be combined with electronics. Thus, they are considered as good candidates for some potential uses, which include bioconductors, biosensors, electro-stimulated drug delivery systems, as well as neuron-, muscle-, and skin-tissue engineering. However, there is lacking comprehensive information on the current state of these electroconductive hydrogels which complicates our understanding of this new type of biomaterials as well as their potential applications. Hence, this review provides a summary on the current development of electroconductive natural polymer-based hydrogels (ENPHs). We have introduced various types of ENPHs, with a brief description of their advantages and shortcomings. In addition, emerging technologies regarding their synthesis developed during the past decade are discussed. Finally, two attractive potential applications of ENPHs, cell culture and biomedical devices, are reviewed, along with their current challenges.

(Invited) Construction of Hemoprotein Assembly Via Heme-Heme Pocket Interaction and Its Photochemical Property

Hemoproteins are metalloproteins which possess iron porphyrin as a prosthetic group (cofactor). These proteins have received much attention not only as biocatalysts but also as promising building blocks for development of new types of biomaterials. Particularly, the heme cofactor in several hemoproteins such as myoglobin, horseradish peroxidase, cytochrome P450, and cytochrome b 562 are replaceable with an artificial heme analog. To functionalize the hemoproteins, our group has focused on the cofactor-substitution with several porphyrinoid metal complexes.1) Furthermore, we have recently introduced a heme moiety onto the myoglobin surface via covalent linkage to obtain a supramolecular protein polymer via interprotein heme–heme pocket interaction.2) In this presentation, we report the recent results of the hemoprotein assembly which is a model of a light-harvesting system.3) A hexameric tyrosine-coordinated heme protein (HTHP) containing photosensitizer molecules was prepared in an effort to construct a biomolecule with engineered photochemical properties. Zn protoporphyrin IX (ZnPP) and Zn chlorin e6 (ZnCe6) are inserted into the apoprotein of HTHP to yield reconstituted proteins which maintain the original hexameric structure of HTHP. Femtosecond transient absorption measurements indicate the occurrence of rapid singlet–singlet annihilation within a few picoseconds for each protein completely reconstituted with the six photosensitizer molecules. This finding supports the fact that the photo-induced energy migration occurs whtin the protein with the zinc complex. The fluorescence quenching efficiencies provided by methyl viologen as an electron acceptor for the completely reconstituted proteins with ZnPP and ZnCe6 are 2.3 and 2.6 fold-higher than that of the corresponding partially photosensitizer-inserted proteins, respectively. This indicates that energy migration occurs among the photosensitizers bound within the protein matrices. These findings are expected to lead to development of new protein-based artificial light harvesting systems. 1) Hayashi, T. In Coordination Chemistry in Protein Cages; Ueno, T.; Watanabe, Y., Eds.; Wiley: Hoboken, US, 2013; Chapter 4, pp 87–110. 2) Oohora, K.; Onoda, A.; Hayashi, T. Chem. Commun. 2012, 48, 11714–11726. 3) Oohora, K.; Mashima, T.; Ohkubo, K.; Fukuzumi, S.; Hayashi, T. Chem. Commun. 2015, 51, 11138–11140.

Applications of New Types of Biomaterials Obtained by Fungal Solid-State Fermentation in Bakery Products Manufacturing

Cereals serve as major food supply for human population. The cereals are rich source of carbohydrates and some proteins, but they are limited in various biologically active compounds such as polyunsaturated fatty acids, carotenoid pigments, coenzyme Q10, etc. Therefore value-added cereal-derived biomaterials have been prepared by the fungal solid state fermentations that could be attractive in food/feed industry. Application of fermented biomaterials into bakery products does not only enrich the final products with new compound (PUFA, ergosterol, etc), but very significantly change the rheological and nutritional and properties of dough and breads such as dough development time and stability, content of starch, glucans, dietary fibre, etc. Sensorial quality of these new products is acceptable for customers. Thus, biotechnologically prepared PUFA-enriched cereals may open novel prospects for the market of functional cereal foods.

Silk fibroin-spider silk-like protein biomaterials for preventing microbial infections

Event Abstract Back to Event Silk fibroin-spider silk-like protein biomaterials for preventing microbial infections Albina R. Franco1, 2, Isabel B. Leonor1, 2, David L. Kaplan3 and Rui L. Reis1, 2 1 University of Minho, 3B's Research Group, Portugal 2 PT Government Associate Laboratory, ICVS/3B’s, Portugal 3 Tufts University, Department of Chemical and Biological Engineering, United States Introduction: Microbial contamination of medical devices, such as sutures, are one of the major causes of hospital infections despite improvements in medical healthcare[1]. Thus, it is important to explore new biomaterials with antimicrobial properties in order to overcome microbial colonisation and biofilm formation. Spider silk has been considered an excellent biomaterial because of its toughness, strength and outstanding elasticity[2]. Also, through recombinant DNA technology, we can bioengineer and functionalize spider silk-based materials with antimicrobial peptides (AMP), thus evolving a new type of biomaterials[3]. Herein, the aim of this study was to develop silk-based fibers with antimicrobial properties by combining silk fibroin (SF) with recombinant spider silk proteins functionalized with AMP. Materials and Methods: Silk-based sutures were produced by combining spider silk chimeric proteins SSP (6mer and 6mer-HNP1) with different ratios of SF extracted from Bombyx mori through wet-spinning. The structure and topography of the sutures were characterized by scanning electron microscopy (SEM) and the tensile properties and knot strength of the sutures was assessed using an INSTRON 5540 Universal Machine. The formation of biofilm on the fibers was assessed and hemolytic effects of the materials were evaluated. Results and Discussion: Silk fibers containing spider silk 6mer or 6mer-HNP1 showed improved tensile behaviour when compared to silk fibers without SPP (Figure 1). The results suggest that the combination of spider silk chimeric proteins with SF increased the tensile stress of the fibers, when compared to those without spider silk chimeric proteins. Figure 1. A- Silk based fiber with 15% silk fibroin; B- Stress-strain curves of the fibers. No bacterial biofilm was observed on the fibers containing SSP functionalized with AMP, suggesting that the presence of the 6mer-HNP1 prevented the formation of biofilm. Conclusions: The outcomes suggest that silk-based fibers functionalized with AMP showed better mechanical properties when compared to silk fibers alone. The data also demonstrate the positive effect of the presence of AMP in preventing biofilm formation on the fibers, suggesting that the functionalized silk fibers could be used as a new strategy to produce sutures capable of preventing microbial proliferation, while retaining useful mechanical properties. Further investigation is still need in order to understand the in vivo performance of sutures and their physical changes during wound healing. This work was supported by national funds through the Portuguese Foundation for Science and Technology under the scope of the project PTDC/BBB-BIO/0827/2012.

Formation of lens-like vesicles induced via microphase separations on a sorbitan monoester membrane with different headgroups

The microphase separation of lipid molecules on a vesicle membrane can be induced, depending on the difference in the geometric structures of their headgroups. Through cryo-transmission-electron-microscopy analysis, a lens-like vesicle was prepared by mixing 50wt% Span 40 (sorbitan monopalmitate) and 50wt% Tween 40 [polyoxyethylene (20) sorbitan monopalmitate]. Considering the molecular structures of Span 40 and Tween 40, the high-curvature region was mainly formed by Tween 40. As determined by Fourier-transform infrared spectroscopy, dielectric-dispersion analysis, and differential scanning calorimetry, a hydration layer was likely formed because polyoxyethylene conjugates with the headgroups of Tween 40. These investigations of the obtained self-assembled aggregates of nonionic surfactants with heterogeneous surfaces could contribute to the development of new types of biomaterials.