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As the interest in the recycling of byproducts and resources derived from agriculture has increased, research on the application of sericin abandoned in the silk industry has been continuously carried out, but there is a limit due to the weak mechanical properties. Recently, nanocellulose has been attracting attention as an optimal reinforcing material to improve the deficient physical properties of natural polymers. In the present study, bamboo-derived cellulose nanofibrils (B-CNFs) were prepared and used as a facile reinforcer to improve the mechanical properties of the sericin film. B-CNF was prepared via simple and eco-friendly ultrasonic treatment and whole bio-nanocomposite film fabrication process conducted under aqueous solution condition. The prepared B-CNF was well distributed into the glycerol-plasticized sericin matrix without agglomeration until 10 wt% B-CNF loading, while agglomerated cellulose nanofibrils appeared after 20 wt% B-CNF loading. This uniform distribution of B-CNF not only greatly improved the properties of the sericin film but also affected the hydrophilic properties of bio-nanocomposite film. Moreover, the prepared B-CNF reinforced bio-nanocomposite films had notable antioxidant activity without any additional antioxidant ingredients. These findings support the potential use of B-CNF reinforced sericin films in active food packaging, drug delivery carriers, and in wound dressing materials. Silk and bamboo-derived natural polymeric raw materials and aqueous solvent-based film manufacturing processes will strongly provide cost efficiency and environmental friendliness and can be a suitable replacement of petroleum-based polymer industry and its related application fields.

The enhancement of the metal adsorption and remediation performance of biomass-based adsorbents is an important challenge in heavy metal removal processes. One of the most viable and practical approaches in accomplishing a high metal removal efficiency is the surface modification of natural polymer adsorbents with functional polymeric materials. In the present study, polyethylenimine (PEI)-modified silk sericin beads were fabricated. The PEI modification process was confirmed and analyzed by Fourier transform infrared spectroscopy (FTIR), field emission-scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS)-based elemental analysis. The Cr(VI) remediation capabilities of PEI-modified sericin beads were analyzed by testing Cr(VI) removal from contaminated water. The results show that the Cr(VI) removal capacity of PEI-modified sericin beads was 365.3 mg/g, which is significantly higher than that of pristine sericin beads (34.56 mg/g). During the Cr(VI) removal process, Cr(VI) adsorption and reduction to Cr(III) occurred simultaneously. The results herein reveal that the synthesized PEI-modified sericin beads are a promising material for Cr(VI) adsorption and detoxification of aqueous solution.

Silk fibroin (SF) has attracted great interest as gate dielectric in organic field-effect transistors (OFETs), owing to outstanding characteristics such as high dielectric constant, transparency, flexibility, and solution processability. In this report, we investigated the relationship between the structural properties of SF films and their performance as SF gate dielectrics in OFETs. Solvent vapor treatment with water or methanol altered the structural properties of the SF films, which adopted a β-sheet structure; accordingly, both the surface energy and areal capacitance of the SF films were reduced. Notably, atmospheric water contributed to the increased capacitance of the SF film, especially before the solvent vapor treatment. The growth characteristics of pentacene on the SF films were determined by the surface conditions of the films; in particular, Stranski-Krastanov (layer-plus-island) growth mode with mixed standing-up/lying-down orientation of pentacene on the SF film was observed before solvent vapor treatment, whereas Volmer-Weber mode with standing-up orientation dominated after solvent vapor treatment. Pentacene OFETs based on the untreated SF film exhibited a higher on-current compared with the devices based on the solvent vapor-treated SF film. The hydroscopic characteristics of the untreated SF film enhanced its capacitance, thereby inducing accumulation of hole carriers. The present results show that the structural characteristics of SF films have a marked impact on the electrical properties of OFETs based on SF gate dielectrics. In particular, the water uptake capability of SF is a key factor in the electrical properties of organic electronic devices using SF materials.

In this work, surface acetylation of cellulose nanocrystals was performed to improve their interfacial adhesion with hydrophobic polymer matrix and to restore their thermal stability by removing the sulfate groups. The morphological, chemical, and thermal characteristics of the surface-modified cellulose nanocrystals (ACNs) were confirmed by field emission-transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, poly(butylene succinate) (PBS)/ACNs nanocomposites were also prepared via melt-mixing process, and the reinforcing effects of ACNs on the thermal, mechanical, and biodegradable properties of the nanocomposites were investigated. The Young’s modulus and tensile strength of the PBS/ACN nanocomposites increased from 115.36 and 33.67 MPa for the neat PBS to 130.55 MPa and 39.97 MPa, respectively. The thermal stability and biodegradability of the nanocomposites also increased with increasing ACN content.

Lignin is the second most abundant renewable biomass-derived natural resource that has been used to replace traditional petrochemical-based materials. However, fabricating the lignin component into the various forms required for practical application is still challenging. In this work, we fabricated water-resistant lignin/poly(vinyl alcohol) (PVA) blend fibers by wet spinning and glutaraldehyde crosslinking methods. The effect of the lignin/PVA blend ratio and glutaraldehyde crosslinking process on the physicochemical properties of wet-spun lignin/PVA blend fibers were studied using maximum draw ratios, hydrolytic degradation profiles, and mechanical properties. Furthermore, the hexavalent chromium [Cr(VI)] removal behavior of lignin/PVA blend fibers was investigated according to the effect of pH, initial Cr(VI) concentration, and contact time. The wet-spun lignin/PVA blend fiber achieved excellent water stability through glutaraldehyde crosslinking and exhibited notable Cr(VI) adsorption capacity (350.87 mg/g) and good regeneration ability. These findings demonstrate that glutaraldehyde-crosslinked lignin/PVA blend fibers could be promising adsorbents for the remediation of heavy metal species containing textile wastewater.

The utilization of sericin should be expanded to increase the availability of silkworm silk. However, the poor mechanical properties and susceptibility to moisture of sericin have continuously restricted its use. In this study, a facile crosslinked sericin film was prepared using a glucose-induced Maillard reaction, and the physicochemical properties and antioxidant functionality of the crosslinking reaction were investigated. The glucose-induced Maillard reaction can be conducted in an environmentally friendly manner through a simple heat treatment of sericin at 90 °C, and the degree of crosslinking can be adjusted by controlling the amount of added glucose. The glucose-induced Maillard reaction improves the mechanical properties of the sericin film, reduces its vulnerability in a moist environment, and provides UV protection and improved antioxidant activity.

The main purpose of this study was to produce succinic acid from hemicellulose in lignocellulosic biomass by successive process without purification as a biorefinery concept. Liquid hot water (LHW) treatment was conducted to extract water soluble hemicelluloses from Quercus mongolica to produce furfural from lignocellulosic biomass. Additional acid catalyzed dehydration was conducted to liquid hydrolysate from LHW treatment for furfural production. At 170 °C of reaction temperature, 42% of furfural yield was achieved from pentose in liquid hydrolysate. This Acid treated liquor (ATL) was treated with hydrogen peroxide to oxidize furfural to C4 dicarboxylic acid such as succinic or maleic acid. Main product was succinic acid which is produced by oxidation of furfural, and minor amount of maleic acid was produced via oxidation. The xylose was degraded to furfural and then oxidized to succinic acid, while acid soluble lignin inhibited succinic acid production by reacting with intermediates of succinic acid. This results indicated that hemicellulose rich liquid hydrolysate has potential to source for succinic acid without further purification.

Electrospinning of aqueous gelatin solution obtained from bovine or porcine sources has been difficult to achieve without additional facilities, such as a temperature control oven or heating cover. Gelatin from cold-water fish has low contents of proline (Pro) and hydroxyproline (Hyp) compared with mammalian-derived gelatin. For this reason, the fish-derived gelatin maintains a sol state without showing gelation behavior at room temperature. In the present study, we prepared an ultrafine fish gelatin nanofibrous web by electrospinning from aqueous solutions without any additive polymers or temperature control facilities. The concentration and viscosity of fish gelatin are the most important factor in determining the electrospinnability and fiber diameter. Electrospinning of aqueous fish gelatin has the highest nanofiber productivity compared to other organic solvent systems. Using glutaraldehyde vapor (GTA), the water stability was improved and substantial enhancement was achieved in the mechanical properties. Finally, the cytotoxicity of a fish gelatin nanofibrous scaffold was evaluated based on a cell proliferation study by culturing human dermal fibroblasts (HDFs) compared with a fish gelatin film and nanofibrous mat from mammalian gelatin. The result shows better initial cell attachment and proliferation compared with the fish gelatin film and no significant difference compared with mammalian-derived gelatin nanofibrous mat. We expect that electrospinning of aqueous fish gelatin could be an effective alternative mammalian gelatin source.

For drug delivery, uncontrolled drug crystallization is the most important and well-described problem which affects the compatibility between target drug and carrier polymer matrix. The crystallization of drugs makes a drug delivery system unstable and it causes a drop the drug loading efficiency and unpredictable release behavior. Recently, the electrospinning process which has rapid solvent evaporation speed has been proposed to prevent the drug crystallization during the drug loading process. In the present study, a fast-dissolving nanofibrous drug delivery carrier was prepared via electrospinning of aqueous fish gelatin as the polymer carrier and caffeine as the hydrophilic model drug under environmentally friendly conditions. Fish gelatin electrospinning was able to produce caffeine loaded gelatin nanofibers with a diameter of 200–220 nm. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) data clearly showed that the amorphous state of caffeine was well incorporated into ultrafine nanofibrous carrier whereas crystalline caffeine was dispersed into conventional fish gelatin film. Fish gelatin nanofibers were able to load two times more caffeine (20 mg ml−1) than conventional caffeine-loaded polymer nanofibers. The fish gelatin nanofibrous mat has good flexibility compared to film due to its interporous nanofiber network. The fish gelatin nanofibrous mats disintegrated within 1.5 s, 27 times faster than films. Fish gelatin nanofibers also showed that most caffeine was released within 10 seconds, which is faster than fish gelatin film and free caffeine drugs. These fish gelatin nanofibers showed 10 times faster caffeine release rates than other caffeine loaded polymer nanofibers. Electrospun fish gelatin nanofibrous mats can be used in biomedical fields especially for the ultra fast delivery of hydrophilic drugs or active ingredients.

In this study, chemically modified lignin and alginate (Alg) hybrid spherical adsorbents exhibiting highly effective adsorption performance for cationic dyes were simply prepared. Carboxylated lignin (C-Lig) was prepared by simple peracetic acid oxidation. Thereafter, through encapsulation of C-Lig into Alg beads was conducted. As the encapsulated amount of C-Lig increased, a higher methylene blue (MB) removal capacity was observed due to the introduction of carboxylated anions on the surface. The adsorption isotherm of Alg/C-Lig beads followed the Langmuir model and exhibited a high monolayer maximum adsorption capacity (qm) of 613 mg/g due to the driving force which is electrostatic interaction between the cationic dye and the anionic group of C-Lig. According to intraparticle diffusion theory, the adsorption behavior proceeded in surface adsorption and internal diffusion during 6 h of the adsorption process. Desorption of MB molecules was found to occur easily via a change in only the pH condition of the solution, and it was possible to maintain over 80% of stable adsorption efficiency even after 5 repeated adsorption/desorption cycles. The facile fabrication process of the Alg/C-Lig beads and superior MB removal performance imply that the Alg/C-Lig beads show a high possibility to purify dye wastewater especially cationic dye molecules.

In this study, gelatin nanofibers that were stable against hydrolytic degradation environment were prepared via electrospinning of aqueous fish gelatin, an eco-friendly sugar crosslinking agent, and a mild heat treatment crosslinking process. Next, the formation of the Maillard reacted products according to the sugar type and the physicochemical properties and antioxidant functions of the sugar-crosslinked gelatin nanofibers were investigated. The addition of sugar to the gelatin nanofibers increased the Maillard reactivity in the order of sucrose

CsPbBr3 perovskite solar cells (PSCs) have been extensively developing for high stability and open-circuit voltage applications. Typically, 2-propanol (IPA) is used as a rinsing solvent during the two-step dipping production process of CsPbBr3. However, we evidenced that the conventional IPA-rinsing step caused the formation of an undesirable Cs4PbBr6 phase resulting in poor surface topography and limited charge transport properties. Surface engineering using IPA-based rinsing was found to be inefficient owing to the poor solubility of CsBr in IPA. Alternative rinsing solvents such as ethanol and methanol were studied in this work. Notably, ethanol-rinsed CsPbBr3 (E-CsPbBr3) showed a pure-phase with a highly-compacted crystalline structure, based on suitable solubility. Because of the high purity of the perovskite crystal and large-size grains, charge extraction properties were improved, and the non-radiative recombination process was suppressed in E-CsPbBr3. Device fabrication demonstrated that average power conversion efficiency (PCE) increased from 4.77% to 6.56% by using ethanol as a rinsing solvent. The best-performing cell showed PCE of 6.89%, with exceptional stability with practically constant PCE after aging for 1030 h under humid ambient air. These remarkable experimental findings enable us to suggest a new standard process for the development of stable and high-performance CsPbBr3-based PSCs.

Nanofibers prepared from cellulose derivatives are a suitable support for enzyme immobilization. We selected a methyl cellulose (MC) nanofibrous mat for enzyme immobilization. First, we established the electrospinning conditions for the preparation of the MC nanofibrous mat. A mixture of ethanol and water at a volume ratio of 1:1 was selected as the solvent of MC for electrospinning. An MC concentration of 5 wt% and a flow rate of 0.5 mL/h were employed to ensure stable electrospinning without bead formation. By varying the applied voltage, the sizes of the MC nanofibers could be controlled in the range of 50 to 80 nm, and an applied voltage of 18 kV was selected for further experimentation. The MC nanofibrous mats were cross-linked with glutaraldehyde under acidic conditions for 12 h in order to increase the stability of the mats in water. Lipase was directly immobilized onto cross-linked MC nanofibrous mats without a further activation step, and 34.82 µg of lipase was immobilized per mg of support. The reusability test showed an unexpected loss of activity after second reuse due to a loss of lipase during the washing procedure promoted by the surface erosion of the MC nanofiber. This problem was solved by introducing crosslinked enzyme aggregates (CLEA) to the surfaces of MC nanofibers. CLEA formation enhanced the activity of lipase per mg of support by almost 5-fold compared with the original lipase-immobilized MC nanofibrous mat. The reusability was also enhanced: more than 90% of the initial activity was retained after seven reuses.

We fabricate transparent cellulose nanopapers with significantly enhanced flame retardancy by a vacuum filtration assisted layer-by-layer deposition method. Flame retardancy is enhanced by increasing the layer-by-layer thickness while not hampering optical transparency of the nanopapers. Thermal degradation and combustion behaviors show that the nanopapers have been successfully functionalized by phosphorus and amine compounds that act effectively as intumescent and blowing agents. Based on the heat release rate of the various nanopapers herein, we propose that the area of the second peak in the heat release rate can serve as an indicator for coating efficiency of these flame retardant materials. We also suggest a possible mechanism behind the material's flame retardancy where by the phosphorus and blowing materials promote intumescent carbonaceous and porous char layers that prevent diffusion of oxygen and heat penetration into the underlying cellulose nanopapers.

Nanocellulose can be categorized into cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs). CNFs and CNCs are oxidized by periodate oxidation to introduce dialdehyde groups, which can act as a crosslinking agent. Polyvinyl alcohol (PVA) is widely used in food packaging, however, it is vulnerable to aqueous environments. In this study, dialdehyde nanocellulose-reinforced PVA nanocomposite films were fabricated to enhance the water resistance. CNF and CNC were oxidized using varying amounts of sodium periodate and the selected fillers were designated as DCNF and DCNC, respectively. In the case of DCNF, physicochemical networking effect was induced to PVA, while DCNC showed only chemical network reinforcement effect. However, both PVA/DCNF and PVA/DCNC composite films have significantly improved vulnerabilities in moisture environment compared to PVA films. These results indicate that while physical network structures are important, the chemically formed network structures can play a crucial role in enhancing the water resistance of PVA films.

Lignin, natural aromatic polymer derived from plant dry matter, is second abundant biopolymer. Recently, interest in applications of lignin, especially as an adsorbent material is increasing. However, the physicochemical complexity of lignin significantly reduces access to practical environmental remediation processes. Also, there is a limitation because the adsorption performance of the pristine lignin materials is not superior to that of commercial adsorbent and ion exchange resin material. In this study, spherical lignin particles with high physicochemical stability and excellent Cr(VI) adsorption capacity are prepared using a polyethylenimine (PEI) modification strategy. This modification process significantly improves the mechanical properties and water stability of lignin by complementing the instability of lignin particles. In addition, the PEI-lignin particles exhibit a superior Cr(VI) removal capability (657.9 mg/g, the highest value for a PEI-modified natural adsorbent), which is attributed to their structural stability and introduced amine functional groups. The Cr(VI) removal with PEI-lignin particles is performed via intra-particle diffusion and adsorption followed by covalent bonding combined with a reduction process. Moreover, the PEI-lignin particles exhibit excellent reusability, which sustains their high adsorption efficiency over a long and repeated adsorption period. The results herein strongly support the potential use of PEI-lignin particles as a high performance bio-sorption material for heavy metal removal and its detoxification in aqueous wastewater streams. Evidently, this lignin-based bio-sorbent manufacturing system can provide sustainable bio-resource recycling and cost efficiency.

As the interest in environmentally friendly materials and concerns regarding depletion of petroleum resources has increased, the research on natural polymers is being actively pursued. Among the various materials based on natural polymeric resources, the interest in using natural fibers in bio-composites has grown due to their lightweight, non-toxicity, low cost, and abundance. However, the lack of interfacial adhesion between filaments and poor water resistance make the use of natural fiber-based polymer composites less attractive. To overcome these drawbacks, formaldehyde-based synthetic binders have been used. However, this requires an additional synthesis of the binder, and potential toxicity problems exist. In this work, robust and rigid natural polymer nonwoven preforms were prepared by mixing jute fibers with silk sericin (SS). SS was employed as a natural facile binder and the strong binding between jute fibers and SS resulted in remarkable enhancements in tensile strength, elongation, and toughness, which increased up to 539.1, 385.7, and 1943.8%, respectively, compared with the pristine jute nonwoven. In addition, the dense and rigid structure obtained through SS coating ensured the structural stability of the nonwoven preforms in moisture environments. Silkworm cocoon-structured natural polymer nonwoven preforms with excellent mechanical strength and higher physical stability may have more potential utilization in the composite material fields.

Keywords: Silk, fibroin, sericin, dye, interface Understanding the interactions between fibroin and sericin is crucial in solving the mechanism of silk spinning. In this study, various commercially available dyes were used to monitor the interface between fibroin and sericin during the gelation of fibroin. The phase separation between fibroin and sericin could be observed by the addition of azo dyes over a certain molecular weight. Furthermore, the addition of the dyes to the sericin layer showed vivid phase separation over addition to the fibroin layer.

A bead-shaped biosorbent for removal of Cr(VI) from industrial waste waters/aqueous media was fabricated using water soluble Spirulina platensis extract (SPE). The addition of LiCl to DMSO affected the solubility of SPE, and 1 M LiCl/DMSO was the optimal solvent system for the preparation of SPE beads. The shape of the SPE bead was determined by the concentration of SPE, and the type of coagulant affected the mechanical properties of the bead. The optimum pH for the Cr(VI) adsorption was 2.0. The maximum adsorption capacity of the SPE beads was 41.12 mg/g at pH 2.0, and the adsorption behavior of Cr(VI) on the SPE beads followed the Brunauer–Emmett–Teller (BET) isotherm. The results indicated that 0.1 M NaOH was the most effective desorption agent. The successive recycling of the adsorption–desorption process was stable for more than five cycles, and the recycling efficiency was 70%.

Natural silk spinning offers several advantages over the synthetic fiber spinning, although the underlying mechanisms of this process are yet to be fully elucidated. Silkworm silks, specifically B. mori, comprise two main proteins: fibroin, which forms the fiber, and sericin, a coextruded coating that acts as a matrix in the resulting nonwoven composite cocoon. To date, most studies have focused on fibroin's self-assembly and gelation, with the influence of sericin during spinning receiving little to no attention. This study investigates sericin's effects on the self-assembly of fibroin via their natural phase-separation. Through changes in sample opacity, FTIR, and XRD, we report that increasing sericin concentration retards the time to gelation and β-sheet formation of fibroin, causing it to adopt a Silk I conformation. Such findings have important implications for both the natural silk spinning process and any future industrial applications, suggesting that sericin may be able to induce long-range conformational and stability control in silk fibroin, while being in a separate phase, a factor that would facilitate long-term storage or silk feedstocks.

Silk sericin (SS) microparticles prepared using the electrospraying method were used for the removal of Cr(VI). SS microparticles exhibited better Cr(VI) adsorption capacity than that of SS macrobeads due to the increased surface area. The optimum pH for Cr(VI) adsorption was 1–2, and the adsorption kinetics followed pseudo secondorder kinetics. The adsorption behavior followed three stages: initial external mass transportation, limited intraparticle diffusion and near equilibrium stage. From the isotherm model study, the Brunauer-Emmett-Teller (BET) model exhibited a very good fit for Cr(VI) adsorption, indicating that SS microparticle has multiple layers and homogeneous active binding sites. The adsorption capacity increased with an increase in the initial Cr(VI) concentration and a decrease in the dosage of the biosorbent. Open image in new window

In this study, we examined the effects of a dextran-modified silk fibroin nanofibrous mat (D-SFNM) on wound healing. To increase the hydrophilicity of silk fibroin (SF), the SF nanofibrous mat (SFNM) was modified with oxidized dextran. The D-SFNM absorbed water faster than the SFNM, and the swelling ratio was increased by approximately 80 % compared with the SFNM. An in vitro cell (NIH3T3) test revealed that fewer cells attached to the D-SFNM than the SFNM, but the proliferation of cells was not significantly affected by the presence of dextran. An in vivo wound healing test with mice indicated that the D-SFNM resulted in a good wound recovery effect similar to a commercial wound dressing material. The increased hydrophilicity of the D-SFNM might balance the moist environment at the wound site, which improves the wound healing compared with the SFNM.

Heavy metal pollution is a serious problem that harms the environment and human health. As a means ofremoving heavy metal ions, especially Cr(VI), from a solution, we prepared a nanofibrous membrane from zein pro-tein which is derived from maize. The zein nanofibrous membrane (ZNM) was prepared by using an 80% ethanol solu-tion as a solvent. The resulting fiber had a ribbon-like structure. The size of the nanofiber could be controlled byvarying the concentration of the zein in the ethanol solution. The ZNM was mounted in a membrane holder and aCr(VI) feed solution was then continuously passed through the ZNM. The adsorption of Cr(VI) reached equilibriumwithin 3 min, indicating the rapid adsorption of the Cr(VI). To regenerate the ZNM adsorbent, the adsorbed Cr(VI) wasremoved by adding 0.1 M NaOH. We believe that ZNM would be an effective means of removing Cr(VI) from indus-trial waste.Keywords: zein, bioadsorption, electrospinning, chromium, biosorbent 1. 서론 다양한 산업 폐수에 함유된 중금속으로 인한 수질 오염은 환경 및 생태계 뿐만 아니라 인체에 노출될 경우 건강에 해로운 영향을 미칠 수 있어 문제가 되고 있다. 그중 목재의 방부과정이나 금속 도금, 가죽의 제혁과정에서 발생하는 크롬 이온은 여러 나라에서 규제대상에 포함된 중금속으로 특히 3가 이온과 6가 이온으로 존재할 때 독성이나타난다. 그 중 6가 크롬 이온의 경우 인간의 장기에 축적되어 간이나 신장 손상을 가져오고 어지러움을 유발하는등 인체에 유해한 영향을 미친다. 더욱이 6가 크롬 이온은3가 크롬 이온보다 물에 잘 용해되는 성질을 가지고 있어보다 더 심각한 문제를 야기할 수 있다[1]. 따라서 산업폐수 내의 6가 크롬 이온을 제거하기 위한 연구가 활발히 진행되고 있다[2]. 수용액 내에 존재하는 중금속 이온의 제거는 흡착, 이온교환, 화학적 침전, 산화 환원 작용 및 역삼투 등의 다양한방법으로 가능하다[3]. 그중 흡착은 다른 방법에 비하여 효율이 높고, 비용이 적게 들며, 비교적 쉽게 처리할 수 있다는 장점이 있다. 현재 중금속 흡착제로는 활성탄이 널리 이용되고 있지만, 농산물의 가공과정에서 발생하는 농업 부산물에 포함된 단백질도 다양한 화학적 작용기를 가지고있어 중금속 흡착제로 사용이 가능하다. 이러한 농업부산물의 활용은 결과적으로 폐기물을 재사용하는 것으로 자원을 효율적 사용할 수 있을 뿐만 아니라 경제적 측면에서도비용이 적게 든다는 장점을 가지고 있다[4]. 이와 관련된기존 연구를 살펴보면 면화씨 단백질로 제조한 하이드로겔(hydrogel)[5]이나 콩 단백질로 제조한 미소중공구체(hollowmicrosphere)[6] 및 하이드로겔[7] 등이 중금속 흡착제로 검토된 바 있다. 제인(zein)은 옥수수의 주요 저장 단백질로 배젖에 주로분포하며 전체 옥수수 단백질 양의 50% 정도를 차지한다.또한 밀 단백질과 더불어 프롤라민(prolamin) 계열의 단백질로서, 프롤린과 류신, 글루탐산의 함량이 높다. 일반적으로 프롤라민 계열의 단백질은 알콜 수용액 및 극성 유기용매에 잘 용해되는 성질을 가지는데[8], 제인은 이러한 용매에 고농도로 용해가 가능하며 필름 등으로 성형한 후에는물에 잘 녹지 않는 성질이 있다. 이러한 성질로 인하여 최근에는 식품 및 제약산업에서 제인으로 고분자 재료로 활용하기 위한 연구가 많이 진행되고 있다. Fabra 등[9]은 제인을 필름 형태로 소재화하여 식품 포장재로 사용하려는

Silk fibroin (SF) nanofiber scaffold containing microalgae Spirulina extract were prepared by electrospinning and the performance and functionality of the scaffold were evaluated. The viscosity and conductivity of the dope solution of Spirulina containing SF were examined for electrospinability and we found that the morphological structure of SF nanofiber is affected by the concentration of Spirulina extract added. The platelet adhesion and coagulation time test confirmed that the Spirulina containing SF nanofiber scaffold had excellent ability to prevent blood clotting or antithrombogenicity that is comparable to heparin. Low cytotoxicity and excellent cell adhesion and proliferation were also observed for Sprulina containing SF nanofiber scaffold by methylthiazolyldiphenyl-tetrazolium bromide assay and confocal fluorescence microscope using fibroblast and human umbilical vein endothelial cells. Based on these results, we believe SF nanofiber scaffold containing Spirulina extract has the potential to be used as tissue engineering scaffold that requires high hemocompatibility. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 307–318, 2014.

Dialysis is the rate-limiting step in the preparation of aqueous silk fibroin (SF) solution. However, the traditional practice of dialyzing SF solution for at least 48 h to remove LiBr is not based on empirical evidence. The aim of the present study was to systematically measure LiBr content in SF solutions dialyzed for varying lengths of time and assess the potential toxicity of residual lithium ions in cells. Complete removal of lithium ions was not achieved even after 72 h of dialysis, with a residual lithium ion content in the solution of 22.85 mg/l. SF films prepared from solutions dialyzed for 8 and 24 h had predominantly random coil or b-sheet structures, respectively. The residual lithium had little cytotoxicity in NIH3T3 fibroblast cells, but viability was compromised in cells grown on SF film prepared from solution dialyzed for 24 h.

Sericin (SS) is a protein that is secreted by silkworms, but it is usually discarded during the degumming process. To obtain and make use of the sericin, we prepared sericin/glycerol/graphene oxide nanocomposite film. The inherent brittleness of pure sericin film was improved by the addition of glycerol (Glc) as a plasticizer. To compensate for the reduced stiffness, we added graphene oxide (GO) into the SS/Glc film. At concentrations of up to 0.8 wt% relative to SS, GO dispersed evenly in the SS matrix without any agglomeration. The maximum tensile strength (9.5±0.7 MPa) and Young’s modulus (414.4±23.2 MPa) were obtained when the GO content was 0.8 wt% relative to SS. The elongation of SS/Glc/GO nanocomposite film also increased by approximately 40 % compared to SS/Glc film. The strong interfacial interaction between the SS and the GO was responsible for the increased stiffness. The increased elongation was due to the reduced crystallinity of the sericin matrix in the presence of GO.

Silk sericin (SS) has been fabricated into beads using a 1 M LiCl/DMSO solvent and utilized as a heavy metal adsorbent. Among the various heavy metals, we targeted Cr(VI) for adsorption using SS beads and found that its adsorption depended on the coagulant used for the fabrication of the SS beads. When methanol was used as a coagulant, the beads had a better adsorption capacity than when ethanol was used except at pH 1. The adsorption behavior of Cr(VI) on the SS beads followed the BET isotherm. The maximum adsorption capacity was 33.76 mg/g at pH 2. The adsorption of Cr(VI) was confirmed by FT-IR and EDS analyses. Finally, the desorption was carried out using NaOH solution, and it was found that 73.19% of the adsorbed Cr(VI) could be detached.

Although the technique for extracting the Bombyx mori sericin has been extensively known, the extraction of sericin from wild-silkworm cocoons is not yet standardized. The aim of this study was to find the optimal conditions for the extraction of sericin from Antheraea mylitta cocoons, with high yields and minimum degradation. We attempted to apply various protocols for the extraction of the A. mylitta sericin (AmS). Among these, we found that the extraction of AmS with a sodium carbonate solution exhibited the highest yield except the conventional soap-alkali extraction. To find the optimal conditions for the AmS extraction with the sodium carbonate, we changed the concentration of sodium carbonate and the treatment time. With an increase in the sodium carbonate concentration and the extraction time, the yield of AmS increased, but the molecular weight (MW) of AmS decreased. Considering the yield, molecular weight distribution (MWD) and amino acid composition of AmS, we suggest that the optimal conditions for the AmS extraction require treatment with 0.02 M sodium carbonate and boiling for 60 min.

In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A 1 M lithium chloride (LiCl)/dimethyl sulfoxide (DMSO) solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI) adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI) occurred on the heterogeneous surface. Cr(VI) adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI) ions were recovered from the Cr(VI) adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI) ions in industrial wastewater.

Wheat gliadin is an ethanol-soluble fraction of wheat protein. It has several intramolecular disulfide bonds, which are cleavable by reductants such as 2-mercaptoethanol. We added 2-mercaptoethanol into the dope solution prepared by dissolving wheat gliadin in DMSO. The dope solution was spun into an acetone/methanol coagulation bath. The viscosity of the dope solution was increased and the spinnability was also improved by the addition of 2-mercaptoethanol. A maximum draw ratio of 3.5 was achieved with the addition of 2-mercaptoethanol whereas, that of non-added fiber was only 2. Furthermore, the mechanical properties of the fiber were slightly improved by the addition of 2-mercaptoethanol. These positive effects are due to the increase of chain entanglement by the cleavage of intramolecular disulfide bonds.

Silk sericin (SS) can be obtained as a byproduct during the silk fiber process, but its application has been limited due to the brittleness of the SS film. To enhance the flexibility of the SS film, glycerol (Glc) has been added as a plasticizer. The addition of Glc enhanced the elongation property of the SS film when the Glc content was 50-70 wt% of SS. Glc also induced the structural transition of SS from a random coil structure to a β-sheet structure. The inconsistent increase of elongation and β-sheet structure of the SS/Glc film were explained by the content of moisture in the SS/Glc film. The moisture content of the SS/Glc film increased proportionally when the Glc content was higher than 50 wt% of SS, which was the same Glc content range that exhibited the plasticizing effect. Therefore, the plasticizing effect on the SS film may occur not only because of Glc but also because of water. Furthermore, water also contributed to the increase in the β-sheet structure development. Our results suggest that the moisture content in the plasticized protein film may play an important role when the plasticizer has hygroscopic properties.

Silk fibroin (SF) is known to be a biocompatible material, and different forms of SF are used for various applications. However, the application of SF in particle form is rarely reported, compared to other forms. In this study, SF microparticles with a diameter of approximately 250 μm were prepared by the electrospray method, using 1 M LiCl/DMSO as a solvent. The dissolution time of SF in the CaCl2/CH3CH2OH/H2O solution and the concentration of the SF dope solution affected the final morphology of the microparticles. A long dissolution time and a low SF concentration led to the formation of irregular microparticles, but a short dissolution time and a high concentration produced sphere-like microparticles. The shear viscosity of the SF dope solution was the main parameter that affected the morphology of the SF microparticles. Regardless of the dissolution time in the CaCl2/CH3CH2OH/H2O solution and the concentration of the SF dope solution, the shear viscosity of the dope solution must be higher than 0.33 Pa s to produce sphere-like microparticles. Finally, cell adhesion experiments demonstrated that these SF microparticles show potential for use as cell carriers.

Microalgae have recently been recognized as a valuable resource for various applications. Phaeodactylum tricornutum is a diatom that lives in marine water and has an unusually high content of lipids. In this study, we added P. tricornutum into a gelatin dope solution to examine the effect of this diatom using electrospinning. The addition of P. tricornutum extracts increased the conductivity of the dope solution but had little effect on the viscosity. Due to the increased conductivity, the fiber diameter was reduced compared with the neat gelatin nanofiber. The loading of P. tricornutum extracts was confirmed using fluorescence microscopy, and the incorporation of lipids was detected through gas chromatography. The P. tricornutum-loaded nanofiber mat exhibited anti-microbial activity against Escherichia coli and multidrug-resistant Staphylococcus aureus (MRSA). The cell viability test showed that the P. tricornutum-loaded nanofiber has no cytotoxicity. We expect that this antimicrobial P. tricornutum-loaded gelatin nanofiber mat can be applied as a wound dressing.

Silk fibroin (SF) nanofiber scaffold containing microalgae Spirulina extract were prepared by electrospinning and the performance and functionality of the scaffold were evaluated. The viscosity and conductivity of the dope solution of Spirulina containing SF were examined for electrospinability and we found that the morphological structure of SF nanofiber is affected by the concentration of Spirulina extract added. The platelet adhesion and coagulation time test confirmed that the Spirulina containing SF nanofiber scaffold had excellent ability to prevent blood clotting or antithrombogenicity that is comparable to heparin. Low cytotoxicity and excellent cell adhesion and proliferation were also observed for Sprulina containing SF nanofiber scaffold by methylthiazolyldiphenyl-tetrazolium bromide assay and confocal fluorescence microscope using fibroblast and human umbilical vein endothelial cells. Based on these results, we believe SF nanofiber scaffold containing Spirulina extract has the potential to be used as tissue engineering scaffold that requires high hemocompatibility.