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1.
ChemSusChem ; 13(2): 321-327, 2020 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-31729788

RESUMO

With typical nanofibrous structure, silks spun by silkworms and spiders are the representative fibrous proteins that embody excellent mechanical properties and biological functions. However, it is still a challenge to directly extract silk nanofibers (SNFs) from natural silk fibers, to retain their nanostructures and properties, by a human- and environment-friendly approach for practical applications. Here, an all-natural strategy for simple, green, and scalable extraction of silkworm and spider silk protein nanofibers in natural deep eutectic solvents has been developed. The liquid-exfoliated SNFs have adjustable diameters from 20 nm (at the single SNF scale) to 100 nm and could be dispersed in water and organic solvents, enabling the production of useful macroscopic biomaterials. The free-standing SNF membranes made from silkworm silk nanofibers (SSNFs) exhibited cytocompatibility, flexibility, and excellent mechanical performance, providing the ability to fabricate sustainable materials for tissue engineering and green electronics. Moreover, the SSNF could be used as a green and efficient dispersant of multiwalled carbon nanotubes (MWCNTs), and the SSNFs/MWCNTs nanocomposite membranes could be used in wearable devices to monitor human activities.


Assuntos
Nanofibras/química , Nanotubos de Carbono , Proteínas/química , Seda/química , Solventes/química , Dispositivos Eletrônicos Vestíveis
2.
Food Chem ; 309: 125708, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31683151

RESUMO

Herein, corn silk extract and its flavonoids were used to inhibit the formation of Nε-carboxymethyllysine (CML) in a casein glucose-fatty acid model system. Under these optimum extraction conditions, nine major flavonoids were identified and quantified by HPLC-MS/MS. The percent inhibition of CML formation by corn silk extract was 76.57%. The inhibitory mechanism of corn silk extract toward CML formation was further investigated by examining the trapping of glyoxal/methyl glyoxal by the major flavonoids (5 mM) using HPLC-ESI-MS, and mono-, di-, and tri-adducts were found for some flavonoid compounds. The antioxidant activity of the corn silk extract was evaluated by the DPPH and ABTS assays. The scavenging activity of the corn silk extract for DPPH and ABTS was 84.38% and 89.11%, respectively. The results suggested that corn silk extract inhibited CML formation through glyoxal/methyl glyoxal scavenging or by its antioxidant activity attributed to its flavonoid content.


Assuntos
Flavonoides/química , Glioxal/química , Lisina/análogos & derivados , Modelos Biológicos , Zea mays/química , Antioxidantes/química , Caseínas/química , Cromatografia Líquida de Alta Pressão , Ácidos Graxos/química , Flavonoides/análise , Glucose/química , Lisina/química , Lisina/metabolismo , Extratos Vegetais/química , Seda/química , Espectrometria de Massas em Tandem , Zea mays/metabolismo
3.
J Photochem Photobiol B ; 203: 111744, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31887637

RESUMO

Articular cartilage regeneration is a challenging process due to its inadequate ability of self-recovering biological mechanisms. The progresses of cartilage tissue engineering is supported to overwhelmed the repairing difficulties and degenerative diseases. The main goal of the present study is to design biomaterials with suitable physico-chemical, mechanical and biological properties for the carrier of growth factor and improving differentiation of mesenchymal stem cell into damaged cartilage tissues. Herein, TGF-ß loaded hydrogel network was prepared through the chemical interactions between vinyl group of natural polymers. Fourier-transform infrared spectroscopy results show the characteristic peaks at 3074 cm-1, 1713 cm-1, and 810 cm-1, which confirm the existence of the vinyl group and successful formation of maleoyl functionalized Chitosan (MCh). The obtained MCh was freely dissolved in the distilled water up to 8% (w/v). X-ray photoelectron spectroscopy survey spectral results show a peak at 289.0 eV which revealed that the OCO and DS were 1.2% and also evidenced the methacryl substitution of Silk fibroin (SF) nanoformulations. The weight loss and mechanical test were analyzed and the results showed that MSF acts as a foremost crosslinking point with MCh through the reaction between the methacrylate groups of MSF and maleoyl groups of MCh which led to enhancing the density and improved the compressive strength. The maximum drug release activity was recorded in the TGF-ß loaded MCh@MSF hydrogel compared to bare MCh hydrogel. Further, the TGF-ß loaded MCh@ MSF hydrogel exhibited the cell viability percentage nearly at 79-102% for MC3T3-E1 and 88-104% for BMDSCs. Similarly, the TGF-ß loaded MCh@MSF exhibited the highest inhibitory activity against E. coli (83%) than S. aureus (67%). Overall, this study concluded the TGF-ß loaded MCh@MSF showed better biocompatibility and could be utilized in the field of cartilage tissue engineering.


Assuntos
Cartilagem Articular/fisiologia , Quitosana/química , Hidrogéis/química , Regeneração , Seda/química , Fator de Crescimento Transformador beta/metabolismo , Animais , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Hidrogéis/farmacologia , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Camundongos , Nanopartículas/química , Regeneração/efeitos dos fármacos , Reologia , Staphylococcus aureus/efeitos dos fármacos , Engenharia Tecidual , Fator de Crescimento Transformador beta/química
4.
Adv Exp Med Biol ; 1174: 187-221, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31713200

RESUMO

The extraordinary mechanical properties of spider silk fibers result from the interplay of composition, structure and self-assembly of spider silk proteins (spidroins). Genetic approaches enabled the biotechnological production of recombinant spidroins which have been employed to unravel the self-assembly and spinning process. Various processing conditions allowed to explore non-natural morphologies including nanofibrils, particles, capsules, hydrogels, films or foams. Recombinant spider silk proteins and materials made thereof can be utilized for biomedical applications, such as drug delivery, tissue engineering or 3D-biomanufacturing.


Assuntos
Materiais Biocompatíveis , Fibroínas , Nanoestruturas , Proteínas Recombinantes , Aranhas , Animais , Materiais Biocompatíveis/metabolismo , Biotecnologia , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Seda/química , Aranhas/química
5.
Nat Commun ; 10(1): 4378, 2019 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-31558722

RESUMO

Web spiders connect silk proteins, so-called spidroins, into fibers of extraordinary toughness. The spidroin N-terminal domain (NTD) plays a pivotal role in this process: it polymerizes spidroins through a complex mechanism of dimerization. Here we analyze sequences of spidroin NTDs and find an unusually high content of the amino acid methionine. We simultaneously mutate all methionines present in the hydrophobic core of a spidroin NTD from a nursery web spider's dragline silk to leucine. The mutated NTD is strongly stabilized and folds at the theoretical speed limit. The structure of the mutant is preserved, yet its ability to dimerize is substantially impaired. We find that side chains of core methionines serve to mobilize the fold, which can thereby access various conformations and adapt the association interface for tight binding. Methionine in a hydrophobic core equips a protein with the capacity to dynamically change shape and thus to optimize its function.


Assuntos
Fibroínas/metabolismo , Metionina/metabolismo , Seda/metabolismo , Aranhas/metabolismo , Algoritmos , Sequência de Aminoácidos , Animais , Fibroínas/química , Fibroínas/genética , Interações Hidrofóbicas e Hidrofílicas , Metionina/genética , Mutação , Conformação Proteica , Dobramento de Proteína , Multimerização Proteica , Homologia de Sequência de Aminoácidos , Seda/química , Espectrometria de Fluorescência , Aranhas/genética , Termodinâmica
6.
Mater Sci Eng C Mater Biol Appl ; 104: 110003, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500012

RESUMO

Hemostatic materials could reduce avertible death from bleeding during surgery and emergency treatment. To this end, silk fibroin (SF) loaded with Ca2+ (1.8, 3.6 5.4, or 7.2%, w:w) was tested as a new hemostatic material (designated as SF1.8, SF3.6, SF5.4, or SF7.2), and the Ca2+ release rate, platelet adhesion, blood coagulation, cytocompatibility, and antimicrobial properties were investigated. Platelet adhesion on SF1.8 was improved significantly compared with pure SF porous material, and increased with increasing Ca2+ concentration. For SF3.6, platelet adhesion was greater than observed for gelatin and calcium alginate porous materials, clotting occurred earlier, and the complete coagulation time was shorter. Additionally, rabbit ear wound studies revealed that the hemostatic time for SF3.6 was significantly shorter than for gelatin, and similar to that for calcium alginate. The shed blood weight was lowest when SF was loaded with 7.2% Ca2+. The SF3.6 porous material displayed no obvious cytotoxicity, and exhibited satisfactory antibacterial activity against Escherichia coli and Staphylococcus aureus.


Assuntos
Alginatos/química , Materiais Biocompatíveis/química , Cálcio/metabolismo , Fibroínas/química , Seda/química , Animais , Antibacterianos/química , Plaquetas/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Gelatina/metabolismo , Hemostáticos/metabolismo , Porosidade/efeitos dos fármacos , Coelhos , Staphylococcus aureus/efeitos dos fármacos , Tecidos Suporte
7.
Mater Sci Eng C Mater Biol Appl ; 104: 109890, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500018

RESUMO

A protein-polymer blend system based on silkworm silk fibroin (SF) and polylactic acid (PLA) was systematically investigated to understand the interaction and miscibility of proteins and synthetic biocompatible polymers in the macro- and micro-meter scales, which can dramatically control the cell responses and enzyme biodegradation on the biomaterial interface. Silk fibroin, a semicrystalline protein with beta-sheet crystals, provides controllable crystal content and biodegradability; while noncrystallizable PDLLA provides hydrophobicity and thermal stability in the system. Differential scanning calorimetry (DSC) combined with scanning electron microscope (SEM) showed that the morphology of the blend films was uniform on a macroscopic scale, yet with tunable micro-phase patterns at different mixing ratios. Fourier transform infrared analysis (FTIR) revealed that structures of the blend system, such as beta-sheet crystal content, gradually changed with the mixing ratios. All blended samples have better stability than pure SF and PLA samples as evidenced by thermogravimetric analysis. Protease XIV enzymatic study showed that the biodegradability of the blend samples varied with their blending ratios and microscale morphologies. Significantly, the topology of the micro-phase patterns on the blends can promote cell attachment and manipulate the cell growth and proliferation. This study provided a useful platform for understanding the fabrication strategies of protein-synthetic polymer composites that have direct biomedical and green chemistry applications.


Assuntos
Fibroínas/química , Poliésteres/química , Polímeros/química , Seda/química , Animais , Materiais Biocompatíveis/química , Bombyx/química , Varredura Diferencial de Calorimetria/métodos , Microscopia Eletrônica de Varredura/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
8.
Adv Mater ; 31(48): e1904311, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31490597

RESUMO

Spider silks are tougher than almost all other materials in the world and thus are considered ideal materials by scientists and the industry. Although there have been tremendous attempts to prepare fibers from genetically engineered spider-silk proteins, it is still a very large challenge to artificially produce materials with a very high fracture energy, not to mention the high scaling-up requirements because of the extremely low productivity and high cost levels. Here, a facile spider-silk-mimicking strategy is first reported for preparing scalable supertough fibers using the chemical synthesis route. Supertoughness (≈387 MJ m-3 ), more than twice the reported value of common spider dragline silk and comparable to the value of the toughest spider silk, the aciniform silk of Argiope trifasciata, is achieved by introducing ß-sheet crystals and α-helical peptides simultaneously in a pseudoprotein polymer. The process opens up a very promising avenue for obtaining excellent spider fibers.


Assuntos
Fibroínas/química , Ácido Poliglutâmico/análogos & derivados , Seda/química , Animais , Cristalização , Peptídeos/química , Ácido Poliglutâmico/química , Conformação Proteica , Engenharia de Proteínas/métodos , Aranhas , Resistência à Tração
9.
ACS Appl Mater Interfaces ; 11(35): 31605-31614, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31385497

RESUMO

Many postsurgical complications stem from bacteria colony formation on the surface of implants, but the usage of antibiotic agents may cause antimicrobial resistance. Therefore, there is a strong demand for biocompatible materials with an intrinsic antibacterial resistance not requiring extraneous chemical agents. In this study, homogeneous nanocones were fabricated by oxygen plasma etching on the surface of natural, biocompatible Bombyx mori silk films. The new hydroxyl bonds formed on the surface of the nanopatterned film by plasma etching increased the surface energy by around 176%. This hydrophilic nanostructure reduced the bacterial attachment by more than 90% for both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria and at the same time improved the proliferation of osteoblast cells by 30%. The nanoengineered substrate and pristine silk were cultured for 6 h with three different bacteria concentrations of 107, 105, and 103 CFU mL-1 and the cell proliferation on the nanopatterned samples was significantly higher due to limited bacteria attachment and prevention of biofilm formation. The concept and materials described here reveal a promising alternative to produce biomaterials with an inherent biocompatibility and bacterial resistance simultaneously to mitigate postsurgical infections and minimize the use of antibiotics.


Assuntos
Antibacterianos , Biofilmes/efeitos dos fármacos , Escherichia coli/fisiologia , Implantes Experimentais , Membranas Artificiais , Osteoblastos/metabolismo , Seda/química , Staphylococcus aureus/fisiologia , Engenharia Tecidual , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Humanos , Teste de Materiais , Camundongos
10.
Nanoscale ; 11(33): 15448-15463, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31403148

RESUMO

Water scarcity plagues two-thirds of the global population. Interestingly, researchers have found that spider silk exhibits excellent water-collection ability owing to its unique structure and chemical components. Based on this characteristic, numerous bioinspired fibers have been fabricated for water collection. Herein, we review the water-collection process for spider silk and recent vital advances in bioinspired fibriform materials, focusing on the water-collection mechanisms of spindle-knot fibers, which exhibit directional droplet transport, hanging mechanism and hanging ability. Also, we evaluated their water-collection abilities on a micro- and macro-scale, which gave a better view for the design of bioinspired water-collection materials. These advances enable the significant use of bioinspired fibers in water collection, which may be applied in several other fields, such as directional transport, tissue engineering, oil-water separation and biosensors.


Assuntos
Seda/química , Água/química , Animais , Microfluídica , Pressão , Propriedades de Superfície
11.
Molecules ; 24(14)2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31295838

RESUMO

This study introduces a simple and environmentally friendly method to synthesize silica-protein nanocomposite materials using microwave energy to solubilize hydrophobic protein in an aqueous solution of pre-hydrolyzed organo- or fluoro-silane. Sol-gel functionality can be enhanced through biomacromolecule incorporation to tune mechanical properties, surface energy, and biocompatibility. Here, synthetic spider silk protein and organo- and fluoro-silane precursors were dissolved and mixed in weakly acidic aqueous solution using microwave technology. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) images revealed the formation of spherical nanoparticles with sizes ranging from 100 to 500 nm depending, in part, on silane fluoro- or organo-side chain chemistry. The silane-protein interaction in the nanocomposite was assessed through infrared spectroscopy. Deconvoluted ATR-FTIR (Attenuated total reflectance Fourier-transform infrared spectroscopy) spectra revealed silane chemistry-specific conformational changes in the protein-silane nanocomposites. Relative to microwave-solubilized spider silk protein, the ß structure content increased by 14% in the spider silk-organo-silica nanocomposites, but decreased by a net 20% in the spider silk-fluoro-silica nanocomposites. Methods of tuning the secondary structures, and in particular ß-sheets that are the cross-linking moieties in spider silks and other self-assembling fibrillar proteins, may provide a unique means to promote protein interactions, favor subsequent epitaxial growth process, and enhance the properties of the protein-silane nanocomposites.


Assuntos
Micro-Ondas , Nanocompostos/química , Dióxido de Silício/química , Géis de Silicone/química , Seda/química , Aranhas/química , Animais , Microscopia de Força Atômica , Nanocompostos/ultraestrutura , Géis de Silicone/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier
12.
ACS Appl Mater Interfaces ; 11(30): 27353-27357, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31287645

RESUMO

Electronic textiles (e-textiles) are being developed because of their potential applications in wearable and flexible electronics. However, complex procedures and chemical agents are required to synthesize carbon-based e-textiles. Pyroprotein-based e-textiles, obtained by the pyrolysis of silk proteins, consume large amounts of time and energy due to the high-temperature process (from 800 to 2800 °C). In this study, we report a novel method of fabricating pyroprotein-based electronic yarns (e-yarns) using microwave irradiation. Microwaves were applied to pyroprotein treated at 650 °C to remove numerous heteroatoms in a short time without the high-temperature process and chemical agents. The structural modulation was confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy. We found a reduction in heteroatoms and enlargement of the carbon region. The temperature-dependent resistance was well explained by the fluctuation-induced tunneling model, which also showed structural modification. The electrical conductivity of the fabricated e-yarns was comparable to that of pyroprotein-based e-textiles heat-treated at 1000 °C (order of 102 S/cm) and showed electrical stability under bending.


Assuntos
Eletrônica , Proteínas/efeitos da radiação , Seda/efeitos da radiação , Têxteis , Condutividade Elétrica , Micro-Ondas , Polímeros/química , Polímeros/efeitos da radiação , Proteínas/química , Pirólise , Seda/química , Dispositivos Eletrônicos Vestíveis
13.
ACS Appl Mater Interfaces ; 11(30): 27426-27434, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31276363

RESUMO

As the most favored high-quality biopolymer, silk fiber is widely used in the textile and medical industries owing to its impressive mechanical properties, wear comfort properties, and biocompatibility. However, its photoinstability, chemical instability, and thermal instability seriously hinder its utilization in luxurious fashionable apparels. Therefore, we herein report the preparation of an ultrathin and uniform TiO2-Al2O3 cloth with a thickness of just six in a thousand of fiber on silkworm silk fiber via atomic layer deposition. In this ultrathin composite cloth, the outer TiO2 layer acts as a sacrificial ultraviolet (UV) absorbent to dissipate large amounts of UV energy. Free radicals and electrons generated by the TiO2 layer are effectively blocked outside the surface of the bulk silk fiber by the inner insulating Al2O3 layer. The excellent UV-resistance of the modified silk fiber was confirmed by a lack of fade in the silk fabric after exposure to UV light for 60 min (equal to continuous exposure to strong sunlight for 3285 days). Compared with silk fiber, the tenacity of the prepared SF-200Al2O3-800TiO2 increased by 18.9% even after sunlight exposure. In addition, both the chemical and thermal stabilities of the modified silk fiber were improved. This technology is expected to have potential applications in various fields, such as high-end fabric development and smart materials, and will further guide material design for future innovations in functional fibers and devices.


Assuntos
Seda/química , Têxteis , Lavanderia , Seda/efeitos da radiação , Propriedades de Superfície , Titânio/química , Raios Ultravioleta/efeitos adversos
14.
Nanoscale ; 11(28): 13431-13439, 2019 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-31281907

RESUMO

Inexpensive and high-efficiency oxygen reduction reaction (ORR) catalysts play a significant role in achieving practical applications of microbial fuel cells (MFCs). Hence, herein, novel nitrogen (N) and trace iron (Fe) co-doped three-dimensional (3D) porous carbon (NFex-C) was synthesized as an excellent ORR catalyst from an interesting salt-induced silk gel, which was beneficial to the spontaneously formation of porosity and boosted the ORR activity. Among the series of NFex-C, NFe0.5-C (1.20% N-ORR/C, 0.07 at% Fe) possessed a higher specific surface area (538.94 m2 g-1) and pore volume (2.158 cm3 g-1). Note that NFe0.5-C exhibited a significantly higher positive initial potential (0.274 V vs. Ag/AgCl) and half-wave potential (0.095 V vs. Ag/AgCl) than other catalysts and commercial Pt/C (20 wt%); this implied that it possessed prominent ORR catalytic activity. In the MFC tests, the output-voltage and maximum power density of NFe0.5-C were enhanced to 517.37 ± 7.87 mV and 605.35 ± 15.39 mW m-2, respectively. Moreover, NFe0.5-C (0.15 $ g-1) exhibits excellent anti-poisoning ability and is thousands of times cheaper than commercial Pt/C (20 wt%, 220.04 $ g-1); therefore, NFe0.5-C should be a prospective catalyst to substitute precious commercial Pt/C in MFCs and even for application in other types of fuel cells.


Assuntos
Fontes de Energia Bioelétrica , Carbono/química , Ferro/química , Nitrogênio/química , Oxigênio/química , Seda/química , Cloreto de Sódio/química , Eletrodos , Oxirredução , Porosidade
15.
Molecules ; 24(14)2019 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-31315278

RESUMO

Ultraviolet B (UVB) irradiation causes adverse effects on the skin. Corn silk contains flavonoids and other bioactive compounds and antioxidants, which may prevent skin photoaging through antioxidant and anti-inflammatory effects. We aimed to investigate the potential photoprotective effects of dietary corn silk on UVB-induced skin damage in mice and the mechanisms behind these effects on human skin cells. Oral administration of corn silk water extract (CS) (2 or 4 g/kg/day) for 19 weeks decreased epidermal thickness, wrinkle formation, and positive staining for PCNA, Ki67, and 8-OHdG, and increased collagen staining in UVB-irradiated SKH-1 hairless mice compared with controls. The pro-inflammatory NF-κB target genes (IL-1ß, iNOS, and COX-2) and MMP-9 expressions were lower in the CS groups, and TGF-ß/Smad signaling increased. Low skin lipid peroxidation and blood DNA oxidation levels and high blood glutathione were detected. Antioxidant transcription factor Nrf2-related catalase and SOD1 proteins and glutaredoxin mRNA levels increased. The results of CS extract treatment and UVB irradiation in HaCaT cells showed the same results in Nrf2 and NF-κB target genes. An LC-MS/MS analysis showed that the CS extract contained potential antioxidants, which might have contributed to its anti-photoaging effects in tissues and cells. CS extract may reduce UVB-induced skin damage through antioxidant and anti-inflammatory mechanisms.


Assuntos
Antioxidantes/administração & dosagem , Seda/administração & dosagem , Envelhecimento da Pele/efeitos dos fármacos , Raios Ultravioleta/efeitos adversos , Zea mays/química , Administração Oral , Animais , Antioxidantes/química , Antioxidantes/farmacologia , Linhagem Celular , Cromatografia Líquida , Modelos Animais de Doenças , Flavonoides/química , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Camundongos , Camundongos Pelados , Fator 2 Relacionado a NF-E2/metabolismo , NF-kappa B/metabolismo , Seda/química , Seda/farmacologia , Espectrometria de Massas em Tandem
16.
Chem Commun (Camb) ; 55(66): 9761-9764, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31355386

RESUMO

The effect of ions on the structure and dynamics of a spider silk protein is elucidated. Chaotropic ions prevent intra- and inter-molecular interactions on the repetitive domain, which are required to maintain the solubility, while kosmotropic ions promote hydrogen bond interactions in the glycine-rich region, which are a prerequisite for ß-sheet formation.


Assuntos
Conformação Proteica em Folha beta , Seda/química , Animais , Cloretos/química , Ligações de Hidrogênio , Concentração de Íons de Hidrogênio , Ressonância Magnética Nuclear Biomolecular/métodos , Proteínas Recombinantes/química , Sódio/química , Solubilidade , Aranhas
17.
Mater Sci Eng C Mater Biol Appl ; 103: 109784, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31349521

RESUMO

Silk, with highly crystalline structure and well-documented biocompatibility, is promising to be used as reinforcing material and build functionalized composite scaffolds. In the present study, we developed chitosan/silk composite scaffolds using silk particles, silk microfibres and nanofibres via 3D printing method. The three forms of silk fillers with varied shapes and dimensions were obtained via different processing methods and evaluated of their morphology, crystalline structure and thermal property. All silk fillers showed different degrees of improvement on printability in terms of ink rheology and printing shape fidelity. Different silk fillers led to different scaffold surface morphology and different roughness, while all reduced the contact angle compared to pure chitosan. Similar reinforcements were observed on compressive modulus, while oscillatory gel strength reinforcement was found to be positively correlated to the filler aspect ratio. Addition of silk introduced no cytotoxicity for that all scaffolds supported a steady cell growth using human fibroblasts. Meanwhile different cellular behaviours were observed on different scaffold surfaces, which can possibly intriguer specific application on soft tissue engineering.


Assuntos
Hidrogéis/química , Nanofibras/química , Impressão Tridimensional , Seda/química , Tecidos Suporte/química , Linhagem Celular , Proliferação de Células , Quitosana/química , Força Compressiva , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Tinta , Reologia , Propriedades de Superfície
18.
Mater Sci Eng C Mater Biol Appl ; 103: 109821, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31349531

RESUMO

Violacein, a natural violet biopigment with efficient bioactivities from Gram-negative bacteria, possesses good affinity to silk fiber and complexes with silver. In this paper, a new approach involving the surface modification of silk fabrics with violacein for the in-situ synthesis of silver nanoparticles (SNPs) was developed. Violacein is used to modify silk material. Subsequently, silk containing bio-violacein was in situ assembled by silver ions and formed SNPs. Functional silk composites (FSC) containing bio-violacein and SNPs were obtained with effective synergistic antimicrobial effects. FSC were characterized by FT-IR spectroscopy, UV-visible absorption spectroscopy, and scanning electron microscopy/energy dispersive spectroscopy, and X-ray diffraction. Exhaustion and amount of violacein on silk fabric were 65.82% and 0.16 g/g, respectively. SNPs were small particles with irregular shapes and sizes <60-70 nm. Antimicrobial activities of the FSC were evaluated against S. aureus, E. coli, and C. albicans. The silk fabric with violacein possessed good antimicrobial activity against S. aureus, with a bacterial reduction of 81.25%. FSC with violacein combined with SNPs integration exhibited good synergistic properties as excellent antimicrobial activities against S. aureus, E. coli, and C. albicans, with microbial reductions of 99.98%, 99.90%, and 99.85%, respectively. FSC not only exhibited the enhanced antimicrobial effects but also exhibited a broadened antimicrobial range.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Indóis/farmacologia , Nanopartículas Metálicas/química , Seda/farmacologia , Prata/farmacologia , Candida albicans/efeitos dos fármacos , Sinergismo Farmacológico , Escherichia coli/efeitos dos fármacos , Nanopartículas Metálicas/uso terapêutico , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Seda/química , Prata/química , Espectrometria por Raios X , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos , Difração de Raios X
19.
Int J Nanomedicine ; 14: 4211-4227, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31239676

RESUMO

Background: Cisplatin is an extensively used anti-neoplastic agent for the treatment of various solid tumors. However, a high incidence of severe ototoxicity is accompanied by its use in the clinic. Currently, no drugs or therapeutic strategies have been approved for the treatment of cisplatin-induced ototoxicity by the FDA. Purpose: The purpose of this study was to investigate the otoprotective effects of dexamethasone (DEX)-loaded silk-polyethylene hydrogel (DEX-SILK) following round window membrane administration in the cisplatin-induced ototoxicity mouse model. Methods: The morphology, gelation kinetics, viscosity and secondary structure of the DEX-SILK hydrogel were analyzed. DEX concentration in the perilymph was tested at different time points following hydrogel injection on the RWM niche. Cultured cells (HEI-OC1), organ of Corti explants (C57/BL6, P0-2), and cisplatin-induced hearing loss mice model (C57/BL6) were used as in vitro and in vivo models for investigating the otoprotective effects of DEX-SILK hydrogel against cisplatin. Results: Encapsulation of DEX with a loading of 8% (w/v) did not significantly change the silk gelation time, and DEX was evenly distributed in the Silk-PEG hydrogel as visualized by scanning electron microscopy (SEM). The concentration of Silk majorly influenced DEX distribution, morphological characteristics, viscosity, and gelation time. The optimized DEX-SILK hydrogel (8% w/v loading, 15% silk concentration, 10 µl) was administered directly onto the RWM of the guinea pigs. The DEX concentration in the perilymph was maintained above 1 µg/ml for at least 21 days for the DEX-SILK, while it was maintained for less than 6 h in the control sample of free DEX. DEX-SILK (5-60 ng/ml) exhibited significant protective effects against cisplatin-induced cellular ototoxicity and notably reduced the production of reactive oxygen species (ROS). Eventually, pretreatment with DEX-SILK effectively preserved outer hair cells in the cultured organ of Corti explants and demonstrated significant hearing protection at 4, 8, and 16 kHz in the cisplatin-induced hearing loss mice as compared to the effects noted following pretreatment with DEX. Conclusion: These results demonstrated the clinical value of DEX-SILK for the therapy of cisplatin-induced ototoxicity.


Assuntos
Cisplatino/efeitos adversos , Dexametasona/farmacologia , Orelha/patologia , Hidrogéis/química , Injeções , Polietilenoglicóis/química , Seda/química , Animais , Materiais Biocompatíveis/efeitos adversos , Bombyx , Linhagem Celular , Cóclea/efeitos dos fármacos , Cóclea/patologia , Dexametasona/uso terapêutico , Modelos Animais de Doenças , Liberação Controlada de Fármacos , Cobaias , Perda Auditiva/induzido quimicamente , Perda Auditiva/tratamento farmacológico , Camundongos Endogâmicos C57BL , Substâncias Protetoras/farmacologia , Espécies Reativas de Oxigênio/metabolismo
20.
Int J Mol Sci ; 20(12)2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31234286

RESUMO

Silk fiber has become a research focus because of its comprehensive mechanical properties. Metal ions can influence the conformational transition of silk fibroin. Current research is mainly focused on the role of a single ion, rather than the whole metal ion environment. Here, we report the effects of the overall metal ion environment on the secondary structure and mechanical properties of silk fibers after direct injection and feeding of silkworms with EDTA. The metal composition of the hemolymph, silk gland, and silk fiber changed significantly post EDTA treatment. Synchrotron FTIR analysis indicated that the secondary structure of silk fiber after EDTA treatment changed dramatically; particularly, the ß-sheets decreased and the ß-turns increased. Post EDTA treatment, the silk fiber had significantly decreased strength, Young's modulus, and toughness as compared with the control groups, while the strain exhibited no obvious change. These changes can be attributed to the change in the metal ion environment in the silk fibroin and sericin in the silk gland. Our investigation provides a new theoretical basis for the natural silk spinning process, and our findings could help develop a method to modify the mechanical properties of silk fiber using metal ions.


Assuntos
Bombyx/metabolismo , Ácido Edético/metabolismo , Metais/metabolismo , Seda/química , Ração Animal/análise , Animais , Fenômenos Biomecânicos , Bombyx/química , Ácido Edético/administração & dosagem , Módulo de Elasticidade , Metais/análise , Conformação Proteica em Folha beta , Seda/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico
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