Synthesis of Silk Fibroin–Glycopolypeptide Conjugates and Their Recognition with Lectin

Drug eluting protein and polysaccharides-based biofunctionalized fabric textiles- pioneering a new frontier in tissue engineering: An extensive review

In the ever-evolving landscape of tissue engineering, medicated biotextiles have emerged as a game-changer. These remarkable textiles have garnered significant attention for their ability to craft tissue scaffolds that closely mimic the properties of natural tissues. This comprehensive review delves into the realm of medicated protein and polysaccharide-based biotextiles, exploring a diverse array of fabric materials. We unravel the intricate web of fabrication methods, ranging from weft/warp knitting to plain/stain weaving and braiding, each lending its unique touch to the world of biotextiles creation. Fibre production techniques, such as melt spinning, wet/gel spinning, and multicomponent spinning, are demystified to shed light on the magic behind these ground-breaking textiles. The biotextiles thus crafted exhibit exceptional physical and chemical properties that hold immense promise in the field of tissue engineering (TE). Our review underscores the myriad applications of drug-eluting protein and polysaccharide-based textiles, including TE, tissue repair, regeneration, and wound healing. Additionally, we delve into commercially available products that harness the potential of medicated biotextiles, paving the way for a brighter future in healthcare and regenerative medicine. Step into the world of innovation with medicated biotextiles-where science meets the art of healing.

Silk chemistry and biomedical material designs

Silk fibroin has applications in different medical fields such as tissue engineering, regenerative medicine, drug delivery and medical devices. Advances in silk chemistry and biomaterial designs have yielded exciting tools for generating new silk-based materials and technologies. Selective chemistries can enhance or tune the features of silk, such as mechanics, biodegradability, processability and biological interactions, to address challenges in medically relevant materials (hydrogels, films, sponges and fibres). This Review details the design and utility of silk biomaterials for different applications, with particular focus on chemistry. This Review consists of three segments: silk protein fundamentals, silk chemistries and functionalization mechanisms. This is followed by a description of different crosslinking chemistries facilitating network formation, including the formation of composite biomaterials. Utility in the fields of tissue engineering, drug delivery, 3D printing, cell coatings, microfluidics and biosensors are highlighted. Looking to the future, we discuss silk biomaterial design strategies to continue to improve medical outcomes.

Biological Effect Evaluation of Different Sized Titanium Dioxide Nanoparticles Using Bombyx mori (Silkworm) as a Model Animal

Titanium dioxide nanoparticles (TiO₂ NPs) are widely used in various disciplines, and it is imperative to evaluate their safety in the environment. In this paper, Bombyx mori (silkworm) was used as a model organism to evaluate the biological effects of different sized TiO₂ NPs, taking into consideration their effect on the larval growth, cocoon shell weight, tissues, and silk produced. The effect of the different sized TiO₂ NPs on the larval and cocoon shell weight was dose-dependent. The highest accumulation of titanium (Ti) following a modified TiO₂ NPs-treated mulberry diet was observed in the midgut. The expression of the light chain fibroin (FIBL) was three times higher in 0.33 g TiO₂ NPs-treated silk gland after 96 h. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis demonstrated that TiO₂ NPs-treated silk fiber (TiSF) exhibited a diminutive decrease in silk fiber (SF) crystallization and β-sheet compared to the control SF, respectively. The tensile tests of SF from silkworm fed with 0.03 g of 25 nm TiO₂ NPs were significantly improved when compared to the control SF. Significant changes in the surface morphology and thermal stability of SF were observed. The antimicrobial activity of TiSF was investigated against Pseudomonas aeruginosa and Staphylococcus aureus, with ciprofloxacin-treated SF acting as a control. It was documented that 0.09 g of 60 nm TiSF was most effective against P. aeruginosa at a zone of inhibition (ZOI) of 21.06 mm when compared with the control SF which recorded a ZOI of 17.19 mm. This study highlighted a different approach in evaluating the biological effects of TiO₂ NPs using the silkworm as a model and assessing their impact on the silk intrinsic property, which will be effective in biotechnology applications.

Matrix Regeneration Ability In Situ Induced by a Silk Fibroin Small-Caliber Artificial Blood Vessel In Vivo

The success of a small-caliber artificial vascular graft in the host in order to obtain functional tissue regeneration and remodeling remains a great challenge in clinical application. In our previous work, a silk-based, small-caliber tubular scaffold (SFTS) showed excellent mechanical properties, long-term patency and rapid endothelialization capabilities. On this basis, the aim of the present study was to evaluate the vascular reconstruction process after implantation to replace the common carotid artery in rabbits. The new tissue on both sides of the SFTSs at 1 month was clearly observed. Inside the SFTSs, the extracellular matrix (ECM) was deposited on the pore wall at 1 month and continued to increase during the follow-up period. The self-assembled collagen fibers and elastic fibers were clearly visible in a circumferential arrangement at 6 months and were similar to autologous blood vessels. The positive expression rate of Lysyl oxidase-1 (LOXL-1) was positively correlated with the formation and maturity of collagen fibers and elastic fibers. In summary, the findings of the tissue regeneration processes indicated that the bionic SFTSs induced in situ angiogenesis in defects.

Site-Specific Functionalization of Recombinant Spider Silk Janus Fibers

Biotechnological production is a powerful tool to design materials with customized properties. The aim of this work was to apply designed spider silk proteins to produce Janus fibers with two different functional sides. First, functionalization was established through a cysteine‐modified silk protein, ntag^CyseADF4(κ16). After fiber spinning, gold nanoparticles (AuNPs) were coupled via thiol‐ene click chemistry. Significantly reduced electrical resistivity indicated sufficient loading density of AuNPs on such fiber surfaces. Then, Janus fibers were electrospun in a side‐by‐side arrangement, with “non‐functional” eADF4(C16) on the one and “functional” ntag^CyseADF4(κ16) on the other side. Post‐treatment was established to render silk fibers insoluble in water. Subsequent AuNP binding was highly selective on the ntag^CyseADF4(κ16) side demonstrating the potential of such silk‐based systems to realize complex bifunctional structures with spatial resolutions in the nano scale.

Unconventional and Facile Fabrication of Chemically Reactive Silk Fibroin Sponges for Environmental Remediation

Silk fibroin and silk microfibers, both derived from silk cocoon, have been widely used for prospective biomedical, energy, and environmental applications. However, various complex and catalyst-based approaches have been adopted for chemical modification and integration of different functionalities in silk fibroin-based materials. Here, both tailored water wettability and mechanical property have been associated with silk microfiber reinforced silk fibroin sponges (SMFRSFSs) through the strategic introduction of β-sheets and a facile and catalyst-free chemical reaction at ambient conditions. While the controlled tailoring of β-sheets in the silk fibroin skeletal framework of the sponges allowed us to modulate the compressive modulus, the 1,4-conjugate addition reaction between amine residues of silk (fiber and fibroin) and acrylate groups of a multifunctional cross-linker provided residual chemical reactivity. Further, the chemically "reactive" sponge was postmodified with the selected alkylamines to introduce a wide range of water wettability (from 36 to 161°) without affecting the mechanical property. Thereafter, the silk cocoon-derived and extremely water-repellent sponge was used for environment-friendly cleaning of oil spillages through selective absorption-based and filtration-based oil/water separation at different and severe aqueous conditions. This silk cocoon-derived mechanically tailorable and chemically reactive sponge could also be useful for various biomedical and energy-related applications.

Enzymatic Azido-GalNAc-Functionalized Silk Fibroin for Click Chemistry Conjugation

Silk is a popular protein biomaterial that has been used for various purposes such as tissue scaffolding, textiles and hydrogels. Various methods for covalent conjugation of functional molecules such as small molecule sensors and enzymes have been developed to create functionalized silk biomaterials. Here, we report a method for silk functionalization by using O-GalNAc-transferases and azide-modified UDP-GalNAc nucleotide sugar substrates to incorporate azide functional groups onto the silk fibroin protein for functionalization with cycloalkynes by click chemistry. Using ppGalNAc-T1 and T13 enzymes, we could transfer azide-modified GalNAc monosaccharides onto fibroin and as a proof of concept, conjugated a strain-alkyne-functionalized Cy5 fluorophore to produce a Cy5-conjugated fibroin hydrogel. This facile azido functionalization of the silk has the potential for attachment of any cycloalkyne moiety.

Controlled radical polymerization of hydrophilic and zwitterionic brush-like polymers from silk fibroin surfaces

Bombyx mori silk fibroin is a fibrous protein whose tunable properties and biocompatibility have resulted in its utility in a wide-variety of applications, including as drug delivery vehicles, wound dressings, and tissue engineering scaffolds. Control of protein and cell attachment is vital to the performance of biomaterials, but silk fibroin is mostly hydrophobic and interacts nonspecifically with cells and proteins. Silk functionalised with hydrophilic polymers reduces attachment, but the low number of reactive sites makes achieving a uniform conjugation a persistent challenge. This work presents a new approach to grow brush-like polymers from the surface of degradable silk films, where the films were enriched with hydroxyl groups, functionalised with an initiator, and finally reacted with acrylate monomers using atom transfer radical polymerisation. Two different routes to hydroxyl enrichment were investigated, one involving reaction with ethylene oxide (EO) and the other using a two-step photo-catalysed oxidation reaction. Both routes increased surface hydrophilicity, and hydrophilic monomers containing either uncharged (poly(ethylene glycol), PEG) pendant groups or zwitterionic pendant groups were polymerised from the surfaces. The initial processing of the films to induce beta sheet structures was found to impact the success of the polymerizations. Compared to the EO modified or unmodified silk surfaces, the oxidation reaction resulted in more polymer conjugation and the surfaces appear more uniform. Mesenchymal stem cell and protein attachment were the lowest on polymers grown from oxidised surfaces. PEG-containing brush-like polymers displayed lower protein attachment than surfaces conjugated with PEG using a previously reported "grafting to" method, but polymers containing zwitterionic side chains displayed both the lowest contact angles and the lowest cell and protein attachment. This finding may arise from the interactions of the zwitterionic pendant groups through their permanent dipoles and is an important finding because PEG is susceptible to oxidative damage that can reduce efficacy over time. These modified silk materials with lower cell and protein attachments are envisioned to find utility when enhanced diffusion around surfaces is required, such as in drug delivery implants.

Safety and efficacy of engineered tissue composed of silk fibroin/collagen and autologous chondrocytes in two patients with cartilage defects: A pilot clinical trial study

BACKGROUND

The objective of this pilot clinical trial study was to evaluate safety and effectiveness of the newly engineered tissue composed of autologous chondrocytes and collagen/fibroin scaffold in repair of osteochondral defects.

METHODS

We implemented a pilot clinical study in two patients with knee osteochondral lesions using engineered tissue composed of scaffold and autologous chondrocytes. Patients were clinically evaluated using the International Repair Cartilage Society score and magnetic resonance imaging (MRI) for one year.

RESULTS

Improved clinical outcomes and objective scores indicated a normal or nearly normal knee in both patients. International Knee Documentation Committee score was upgraded from 34.5 at baseline to 72.4 in the first patient, and 28.7 to 81.6 in the second patient. Visual analogue scale, showing the suffering pain score, was lowered from 8 to 0 in both patients, Western Ontario and McMaster Universities Osteoarthritis Index score representing the physical ability of the patients was changed from 68.1 to 87.1 in Patient 1 and 58.3 to 87.1 in Patient 2, the knee function score, related to the functional ability of the knee, was improved from 70 to 100 in the first patient and from 45 to 91 in the second patient. MRI showed great coverage and integration of the graft in patients, with no effusion, decreased edema and cartilage formation signals.

CONCLUSIONS

The functional and clinical outcomes alongside MRI data showed promising results for regenerating osteochondral defects. A randomized clinical trial study is required to confirm feasibility of this novel engineered tissue in repair of osteochondral defects.

Using In Situ Polymerization to Increase Puncture Resistance and Induce Reversible Formability in Silk Membranes

Silk fibroin is an excellent biopolymer for application in a variety of areas, such as textiles, medicine, composites and as a novel material for additive manufacturing. In this work, silk membranes were surface modified by in situ polymerization of aqueous acrylic acid, initiated by the reduction of various aryldiazonium salts with vitamin C. Treatment times of 20 min gave membranes which possessed increased tensile strength, tensile modulus, and showed significant increased resistance to needle puncture (+131%), relative to 'untreated' standards. Most interestingly, the treated silk membranes were able to be reversibly formed into various shapes via the hydration and plasticizing of the surface bound poly(acrylic acid), by simply steaming the modified membranes. These membranes and their unique properties have potential applications in advanced textiles, and as medical materials.

Fluorescent organotin compounds as dyes in silk fibroin (Bombyx mori): ultrasound-assisted synthesis, chemo-optical characterization, cytotoxicity, and confocal fluorescence microscopy

The fluorescent silk fibroin (FSF) is useful in a number of biomedical applications.

Sugared biomaterial binding lectins: achievements and perspectives

Lectins, a distinct group of glycan-binding proteins, play a prominent role in the immune system ranging from pathogen recognition and tuning of inflammation to cell adhesion or cellular signalling. The possibilities of their detailed study expanded along with the rapid development of biomaterials in the last decade. The immense knowledge of all aspects of glycan-lectin interactions both in vitro and in vivo may be efficiently used in bioimaging, targeted drug delivery, diagnostic and analytic biological methods. Practically applicable examples comprise photoluminescence and optical biosensors, ingenious three-dimensional carbohydrate microarrays for high-throughput screening, matrices for magnetic resonance imaging, targeted hyperthermal treatment of cancer tissues, selective inhibitors of bacterial toxins and pathogen-recognising lectin receptors, and many others. This review aims to present an up-to-date systematic overview of glycan-decorated biomaterials promising for interactions with lectins, especially those applicable in biology, biotechnology or medicine. The lectins of interest include galectin-1, -3 and -7 participating in tumour progression, bacterial lectins from Pseudomonas aeruginosa (PA-IL), E. coli (Fim-H) and Clostridium botulinum (HA33) or DC-SIGN, receptors of macrophages and dendritic cells. The spectrum of lectin-binding biomaterials covered herein ranges from glycosylated organic structures, calixarene and fullerene cores over glycopeptides and glycoproteins, functionalised carbohydrate scaffolds of cyclodextrin or chitin to self-assembling glycopolymer clusters, gels, micelles and liposomes. Glyconanoparticles, glycan arrays, and other biomaterials with a solid core are described in detail, including inorganic matrices like hydroxyapatite or stainless steel for bioimplants.

Facile and versatile solid state surface modification of silk fibroin membranes using click chemistry

Reported is a fast and versatile protocol to surface modify pre-cast silk membranes targeting tyrosine residues.

Electrospun Zein/Gelatin Scaffold-Enhanced Cell Attachment and Growth of Human Periodontal Ligament Stem Cells

Periodontitis is a widespread dental disease affecting 10 to 15% of worldwide adult population, yet the current treatments are far from satisfactory. The human periodontal ligament stem cell is a promising potential seed cell population type in cell-based therapy and tissue regeneration, which require appropriate scaffold to provide a mimic extracellular matrix. Zein, a native protein derived from corn, has an excellent biodegradability, and therefore becomes a hotspot on research and application in the field of biomaterials. However, the high hydrophobicity of zein is unfavorable for cell adhesion and thus greatly limits its use. In this study, we fabricate co-electrospun zein/gelatin fiber scaffolds in order to take full advantages of the two natural materials and electrospun fiber structure. Zein and gelatin in four groups of different mass ratios (100:00, 100:20, 100:34, 100:50), and dissolved the mixtures in 1,1,1,3,3,3-hexafluoro-2-propanol, then produced membranes by electrospinning. The results showed that the scaffolds were smooth and homogeneous, as shown in scanning electron micrographs. The diameter of hybrid fibers was increased from 69 ± 22 nm to 950 ± 356 nm, with the proportion of gelatin increase. The cell affinity of zein/gelatin nanofibers was evaluated by using human periodontal ligament stem cells. The data showed that hydrophilicity and cytocompatibility of zein nanofibers were improved by blended gelatin. Taken together, our results indicated that the zein/gelatin co-electrospun fibers had sufficient mechanical properties, satisfied cytocompatibility, and can be utilized as biological scaffolds in the field of tissue regeneration.

Robust composite silk fibers pulled out of silkworms directly fed with nanoparticles

This paper reports the impacts of direct feeding silkworms with different nanoparticles (Cu, Fe, and TiO₂) on the morphology, structures, and mechanical properties of the resulting silk fiber (SF). The contents of the Cu nanoparticles were 38 times higher in the posterior silk glands and only 2-3 times higher in the SF and in the middle silk glands compared with the controlled groups. Significant changes of the surface morphology, structures, and diameter of the Cu nanoparticle fed SF have been observed, which are attributed to a slight SF protein reconstruction or conformational change in the mixture of silk fibroin and sericin in the silk glands. The resulting Cu-containing SF exhibits good tensile strength of 360MPa and reaches a strain of 38%, which are 89% and 36% higher than those of the natural SF. This study offers a new green strategy for the easy modification to achieve robust composite SF.

In vitro study of novel microparticle based silk fibroin scaffold with osteoblast-like cells for load-bearing osteo-regenerative applications

Silk Fibroin microparticle scaffolds show promise in bone tissue engineering applications.

Poly(l-lysine) modified zein nanofibrous membranes as efficient scaffold for adhesion, proliferation, and differentiation of neural stem cells

Cell viability, adhesion, proliferation, and differentiation of neural stem cells (NSCs) on zein nanofibrous membranes could be improved by poly(l-lysine) modification.

Bioreducible amphiphilic block copolymers based on PCL and glycopolypeptide as multifunctional theranostic nanocarriers for drug delivery and MR imaging

Amphiphilic diblock poly(ε-caprolactone)-b-glycopolypeptides (PCL–SS–GPPs) bearing disulfide bonds were synthesized from a clickable poly(ε-caprolactone)–SS–poly(2-azidoethyl-l-glutamate) diblock copolymer.

Synthesis and self-assembly of diblock glycopolypeptide analogues PMAgala-b-PBLG as multifunctional biomaterials for protein recognition, drug delivery and hepatoma cell targeting

PMAgala-b-PBLG glycopolypeptide analogues might serve as redox-responsive, highly biocompatible multifunctional biomaterial platforms for practical applications.

Synthetic polypeptides: from polymer design to supramolecular assembly and biomedical application

This review highlights the recent advances in the chemical design, supramolecular assembly, and biomedical application of synthetic polypeptides fromN-carboxyanhydrides.

Glycopolypeptide-Grafted Bioactive Polyionic Complex Vesicles (PICsomes) and Their Specific Polyvalent Interactions

Glycopolypeptide-based self-assembled nano-/microstructures with surface-tethered carbohydrates are excellent mimics of glycoproteins on the cell surface. To expand the broad repertoire of glycopolypeptide-based supramolecular soft structures such as polymersomes formed via self-assembly of amphiphilic polymers, we have developed a new class of polyionic complex vesicles (PICsomes) with glycopolypeptides grafted on the external surface. Oppositely charged hydrophilic block copolymers of glycopolypeptide20-b-poly-l-lysine100 and PEG2k-b-poly-l-glutamate100 [PEG = poly(ethylene glycol)] were synthesized using a combination of ring-opening polymerization of N-carboxyanhydrides and "click" chemistry. Under physiological conditions, the catiomer and aniomer self-assemble to form glycopolypeptide-conjugated PICsomes (GP-PICsomes) of micrometer dimensions. Electron and atomic force microscopy suggests a hollow morphology of the PICsomes, with inner aqueous pool (core) and peripheral PIC (shell) regions. Owing to their relatively large (∼micrometers) size, the hollowness of the supramolecular structure could be established via fluorescence microscopy of single GP-PICsomes, both in solution and under dry conditions, using spatially distributed fluorescent probes. Furthermore, the dynamics of single PICsomes in solution could be imaged in real time, which also allowed us to test for multivalent interactions between PICsomes mediated by a carbohydrate (mannose)-binding protein (lectin, Con-A). The immediate association of several GP-PICsomes in the presence of Con-A and their eventual aggregation to form large insoluble aggregate clusters reveal that upon self-assembly carbohydrate moieties protrude on the outer surface which retains their biochemical activity. Challenge experiments with excess mannose reveal fast deaggregation of GP-PICsomes as opposed to that in the presence of excess galactose, which further establishes the specificity of lectin-mediated polyvalent interactions of the GP-PICsomes.

Bioactive polymersomes self-assembled from amphiphilic PPO-glycopolypeptides: synthesis, characterization, and dual-dye encapsulation

Glycopolypeptide-based polymersomes have promising applications as vehicles for targeted drug delivery because they are capable of encapsulating different pharmaceuticals of diverse polarity as well as interacting with specific cell surfaces due to their hollow structural morphology and bioactive surfaces. We have synthesized glycopolypeptide-b-poly(propylene oxide) by ROP of glyco-N-carboxyanhydride (NCA) using the hydrophobic amine-terminated poly(propylene oxide) (PPO) as the initiator. This block copolymer is composed of an FDA-approved PPO hydrophobic block in conjugation with hydrophilic glycopolypeptides which are expected to be biocompatible. We demonstrate the formation of glycopolypeptide-based polymersomes from the self-assembly of glycopolypeptide-b-poly(propylene oxide) in which the presence of an ordered helical glycopolypeptide segment is required for their self-assembly into spherical nanoscale (∼50 nm) polymersomes. The polymersomes were characterized in detail using a variety of techniques such as TEM, AFM, cryo-SEM, and light-scattering measurements. As a model for drugs, both hydrophobic (RBOE) and hydrophilic (calcein) dyes have been incorporated within the polymersomes from solution. To substantiate the simultaneous entrapment of the two dyes, spectrally resolved fluorescence microscopy was performed on the glycopeptide polymersomes cast on a glass substrate. We show that it is possible to visualize individual nanoscale polymersomes and effectively probe the dyes' colocalization and energy-transfer behaviors therein as well as investigate the variation in dual-dye encapsulation over a large number of single polymersomes. Finally, we show that the galactose moieties present on the surface can specifically recognize lectin RCA120, which reveals that the polymersomes' surface is indeed biologically active.

Chitin and chitosan nanofibers: preparation and chemical modifications

Chitin nanofibers are prepared from the exoskeletons of crabs and prawns, squid pens and mushrooms by a simple mechanical treatment after a series of purification steps. The nanofibers have fine nanofiber networks with a uniform width of approximately 10 nm. The method used for chitin-nanofiber isolation is also successfully applied to the cell walls of mushrooms. Commercial chitin and chitosan powders are also easily converted into nanofibers by mechanical treatment, since these powders consist of nanofiber aggregates. Grinders and high-pressure waterjet systems are effective for disintegrating chitin into nanofibers. Acidic conditions are the key factor to facilitate mechanical fibrillation. Surface modification is an effective way to change the surface property and to endow nanofiber surface with other properties. Several modifications to the chitin NF surface are achieved, including acetylation, deacetylation, phthaloylation, naphthaloylation, maleylation, chlorination, TEMPO-mediated oxidation, and graft polymerization. Those derivatives and their properties are characterized.

Coatings and films made of silk proteins

Silks are a class of proteinaceous materials produced by arthropods for various purposes. Spider dragline silk is known for its outstanding mechanical properties, and it shows high biocompatibility, good biodegradability, and a lack of immunogenicity and allergenicity. The silk produced by the mulberry silkworm B. mori has been used as a textile fiber and in medical devices for a long time. Here, recent progress in the processing of different silk materials into highly tailored isotropic and anisotropic coatings for biomedical applications such as tissue engineering, cell adhesion, and implant coatings as well as for optics and biosensors is reviewed.

Emerging bioinspired polymers: glycopolypeptides

This article highlights the very recent advances in glycopolypeptide synthesis via NCA polymerization and first studies on stimuli-responsive solution behavior and self-assembling structures. Yet glycopolypeptides are almost exclusively considered as smart biofunctional materials for use in biomedical applications, for instance in targeted drug delivery, but also have high potential for usage as structural materials to fabricate bioinspired hierarchical structures.

Controlling the cell adhesion property of silk films by graft polymerization

We report here a graft polymerization method to improve the cell adhesion property of Bombyx mori silk fibroin films. B. mori silk has evolved as a promising material for tissue engineering because of its biocompatibility and biodegradability. However, silk's hydrophobic character makes cell adhesion and proliferation difficult. Also, the lack of sufficient reactive amino acid residues makes biofunctionalization via chemical modification challenging. Our study describes a simple method that provides increased chemical handles for tuning of the surface chemistry of regenerated silk films (SFs), thus allowing manipulation of their bioactivity. By grafting pAAc and pHEMA via plasma etching, we have increased carboxylic acid and hydroxyl groups on silk, respectively. These modifications allowed us to tune the hydrophilicity of SFs and provide functional groups for bioconjugation. Our strategy also allowed us to develop silk-based surface coatings, where spatial control over cell adhesion can be achieved. This control over cell adhesion in a particular region of the SFs is difficult to obtain via existing methods of modifying the silk fibroin instead of the SF surface. Thus, our strategy will be a valuable addition to the toolkit of biofunctionalization for enhancing SFs' tissue engineering applications.

Green synthesis of noble metal nanoparticles using cysteine-modified silk fibroin: catalysis and antibacterial activity

Noble metal nanoparticles (NPs) have shown remarkable potential for numerous applications.

Incorporation of Exogenous RGD Peptide and Inter-Species Blending as Strategies for Enhancing Human Corneal Limbal Epithelial Cell Growth on Bombyx mori Silk Fibroin Membranes

While fibroin isolated from the cocoons of domesticated silkworm Bombyx mori supports growth of human corneal limbal epithelial (HLE) cells, the mechanism of cell attachment remains unclear. In the present study we sought to enhance the attachment of HLE cells to membranes of Bombyx mori silk fibroin (BMSF) through surface functionalization with an arginine-glycine-aspartic acid (RGD)-containing peptide. Moreover, we have examined the response of HLE cells to BMSF when blended with the fibroin produced by a wild silkworm, Antheraea pernyi, which is known to contain RGD sequences within its primary structure. A procedure to isolate A. pernyi silk fibroin (APSF) from the cocoons was established, and blends of the two fibroins were prepared at five different BMSF/APSF ratios. In another experiment, BMSF surface was modified by binding chemically the GRGDSPC peptide using a water-soluble carbodiimide. Primary HLE were grown in the absence of serum on membranes made of BMSF, APSF, and their blends, as well as on RGD-modified BMSF. There was no statistically significant enhancing effect on the cell attachment due to the RGD presence. This suggests that the adhesion through RGD ligands may have a complex mechanism, and the investigated strategies are of limited value unless the factors contributing to this mechanism become better known.