Fibroin Research Articles

Silk fibroin/chitosan thiourea hydrogel scaffold with vancomycin and quercetin-loaded PLGA nanoparticles for treating chronic MRSA osteomyelitis in rats

Chronic osteomyelitis presents significant treatment challenges, necessitating an efficient system for infection elimination and bone repair. This study developed a natural hydrogel scaffold using silk fibroin (SF) and chitosan thiourea (CST), incorporating vancomycin (VC) and quercetin (QC) loaded PLGA nanoparticles (NPs) for dual-purpose treatment. SF/CST hydrogel scaffolds exhibited homogeneous porosity and smaller interconnected pore size than pure SF and pure CST hydrogel scaffolds. Optimal PLGA/QC NPs measured 206 nm in size, displayed spherical morphology, had uniform distribution, and achieved 87 % QC loading. The release study showed sustained long-term release of VC and QC from the hydrogel scaffolds for over 20 days. Biocompatibility tests indicated that hydrogel scaffolds promoted osteoblast adhesion without cytotoxicity, with QC-containing scaffolds enhancing osteoblast growth. Antibacterial tests confirmed retained VC activity against methicillin-resistant Staphylococcus aureus (MRSA) in SF/CST. An experimental study assessed the efficacy of the hydrogel scaffolds in a MRSA-infected rat osteomyelitis model. Radiographic scores demonstrated a significant reduction for SF/CST-VC-PLGA/QC NPs compared to control, indicating reduced osteomyelitis effects. Macroscopic evaluations showed notable reductions in gross pathological effects for VC-containing groups. Histopathological assessments revealed significantly lower osteomyelitis scores and higher healing scores in the SF/CST-VC-PLGA/QC NPs, with reduced inflammatory cell infiltration and more organized connective tissue formation. In conclusion, SF/CST-VC-PLGA/QC NPs is an effective dual drug delivery system for osteomyelitis treatment, demonstrating significant antibacterial activity, enhanced bone regeneration, and reduced infection rate.

Unique framework effect induced by uniform silk fibroin dynamic nanospheres enables multiscale hydrogel with outstanding elastic resilience and strain sensing performance

It is a significant challenge to obtain hydrogels simultaneously with low tensile energy dissipation, high compressive resilience and long durability. Herein, the uniform dynamic nanospheres (Sil-4H0.75) derived from 4-Hydroxybutyl acrylate glycidyl ether grafted silk fibroin is designed to overcome this issue. Due to its uniform and dynamic characteristic, Sil-4H0.75 could endow hydrogel with homogeneous multiscale structure and produce unique framework effect. Thus, transparent Sil-4H0.75 crosslinked acrylamide hydrogel doped with Ag nanowires APS3.75%/AgNW0.1 exhibits a high stretchability (1260 %) and outstanding elastic resilience. The tensile energy dissipation ratio maintains a low value of 9 % across a wide 800 % strain range. A high compression resilience ratio of 92.2 % is kept after ten compression cycles under 90 % compressive strain. The orderly AgNWs motion guided by framework effect also make it be used as both tensile and compressive sensors and exhibits high gauge factor of 7.35, outstanding compression sensitivity of 30.379 kPa−1 and excellent durability (up to 2000 cycles). The detection or other applications based on both two sensing modes are also demonstrated. In a word, this work affords a general strategy to achieve high-performance hydrogel based on uniform dynamic nanospheres which exhibits great potential in the applications of flexible wearable strain sensors.

Double Enzyme Active Hydrogel Program Regulates the Microenvironment of Staphylococcus aureus-Infected Pressure Ulcers.

The treatment of infected pressure ulcers (IUPs) requires addressing diverse microenvironments. A pressing challenge is to effectively enhance the regenerative microenvironment at different stages of the healing process, tailoring interventions as needed. Here, a dual enzyme mimetic and bacterial responsive self-activating antimicrobial hydrogel designed to enhance IPUs healing is introduced. This hydrogel incorporates pH-responsive dual enzyme-active nanoplatforms (HNTs-Fe-Ag) encapsulated within a methacrylate-modified silk fibroin (SFMA) and dopamine methacrylamide (DMA) matrix. This composite hydrogel exhibits adaptive microenvironment regulation capabilities. Under the low pH microenvironment of bacterial infection, it has excellent antimicrobial activity by self-activating the •OH generation in conjunction with photothermal effects. Under the neutral and alkaline microenvironment of chronic inflammation, it catalyzes the decomposition of hydrogen peroxide (H2O2) to produce oxygen (O2), thereby alleviating hypoxia and scavenging reactive oxygen species (ROS), which in turn remodulates the phenotype of macrophages. The composite hydrogel demonstrates on-demand therapeutic effects in the microenvironment of infected wounds, significantly enhancing the regenerative microenvironment of IUPs by promoting wound closure, inflammation regulation, and collagen deposition through self-activated antimicrobial action during infection and adaptive hypoxia relief during recovery. This approach offers a novel strategy for developing smart wound dressings.

Disrupting Mycobacterium smegmatis biofilm using enzyme-immobilized rifampicin loaded silk fibroin nanoparticles for dual anti-bacterial and anti-biofilm action

Biofilm formation is a major challenge in the treatment of tuberculosis, leading to poor treatment outcomes and latent infections. The complex and dense extracellular polymeric substances (EPS) of the biofilm provides safe harbour for bacterium enabling persistence against anti-TB antibiotics. In this study, we demonstrated that rifampicin-encapsulated silk fibroin nanoparticles immobilized with antibiofilm enzymes can disrupt the Mycobacterium smegmatis biofilm and facilitate the anti-bacterial action of Rifampicin (RIF). The EPS of M.smegmatis biofilm predominantly comprised of lipids (48.8 ± 1.32 %) and carbohydrates (34.8 ± 4.70 %), similar to tuberculosis biofilms. Pre-formed biofilm eradication screening revealed that hydrolytic enzymes such as β-Glucosidase, Glucose oxidase, ɑ-Amylase, Acylase, and Phytase can exhibit biofilm eradication of M.smegmatis biofilms. The enzyme-mediated biofilm disruption was associated with a decrease in hydrophobicity of biofilm surfaces. Treatment with β-glucosidase and Phytase demonstrated a putative biofilm eradication by reducing the total carbohydrates and lipid composition without causing any significant bactericidal activity. Further, Phytase (250 μg/ml) and β-Glucosidase (112.5 ± 17.6 μg/ml) conjugated rifampicin-loaded silk fibroin nanoparticles (R-SFNs) exhibited an enhanced anti-bacterial activity against pre-formed M.smegmatis biofilms, compared to free rifampicin (32.5±7 μg/ml). Notably, treatment with β-glucosidase, Phytase and ɑ-amylase immobilized SFNs decreased the biofilm thickness by ∼98.84 % at 6h, compared to control. Thus, the study highlights that coupling anti-mycobacterial drugs with biofilm-eradicating enzymes such as amylase, phytase or β-glucosidase can be a potential strategy to improve the TB therapeutic outcomes.

An In Vitro Macrophage Response Study of Silk Fibroin and Silk Fibroin/Nano-Hydroxyapatite Scaffolds for Tissue Regeneration Application.

In recent years, silk fibroin (SF) has been incorporated with low crystallinity nanohydroxyapatite (nHA) as a scaffold for various tissue regeneration applications due to the mechanical strength of SF and osteoconductive properties of nHA. However, currently, there is a lack of understanding of the immune response toward the degradation products of SF with nHA composite after implantation. It is known that particulate fragments from the degradation of a biomaterial can trigger an immune response. As the scaffold is made of degradable materials, the degradation products may contribute to the inflammation. Therefore, in this study, the effects of the enzymatic degradation of the SF/nHA scaffold on macrophage response were investigated in comparison to the control SF scaffold. Since the degradation products of a scaffold can influence macrophage polarization, it can be hypothesized that as the SF and SF/nHA scaffolds were degraded in vitro using protease XIV solution, the degradation products can contribute to the polarization of THP-1-derived macrophages from pro-inflammatory M1 to anti-inflammatory M2 phenotype. The results demonstrated that the initial (day 1) degradation products of the SF/nHA scaffold elicited a pro-inflammatory response, while the latter (day 24) degradation products of the SF/nHA scaffold elicited an anti-inflammatory response. Moreover, the degradation products from the SF scaffold elicited a higher anti-inflammatory response due to the faster degradation of the SF scaffold and a higher amino acid concentration in the degradation solution. Hence, this paper can help elucidate the contributory effects of the degradation products of SF and SF/nHA scaffolds on macrophage response and provide greater insights into designing silk-based biomaterials with tunable degradation rates that can modulate macrophage response for future tissue regeneration applications.

A fully nanofiber-based ultrathin electronic patch for self-powered and multifunctional on-skin applications

On-skin electronics that simultaneously ensure biocompatibility and stable electrical operation on soft tissue is still challenging. This study introduces a dual-layered and natural material based nanofiber platform designed for multifunctional on-skin operation (from energy harvesting to transdermal drug delivery). The ultrathin electronic patch consists of polyaniline (PANI)-coated cellulose nanofibers and silk fibroin nanofibers. The top PANI/cellulose nanofiber layer, exhibiting the resistivity of 0.315 Ω·m and over 90 % light absorbance in full visible range, functions as a flexible electrode. The silk nanofiber layer offers the skin-compatibility and strong adhesion to biological tissues, along with the capability of drug-loading. The nanofiber mesh structure withstands mechanical deformation, including compression, stretching, and bending, while its porous nature enhances breathability and hygiene. The fully nanofiber-based electronic patch platform is flexible, adheres well to the skin, and conforms to curved surfaces. By integrating the conductive properties of PANI with the biocompatibility of silk fibroin, this dual-layered membrane enhances the efficacy of transdermal drug delivery while offering multifunctional capabilities such as energy harvesting in a triboelectric nanogenerator (TENG), programmable drug delivery, and thermal therapy. This innovative approach paves the way for advanced biomedical applications by combining multiple functionalities in a single platform.

Auranofin loaded silk fibroin nanoparticles for colorectal cancer treatment.

Colorectal cancer (CRC) is the second most common cause of cancer related deaths worldwide and the prevalence in young people especially is increasing annually. In the search for innovative approaches to treat the disease, drug delivery systems (DDS) are promising owing to their unique properties, which allow improved therapeutic results with lower drug concentrations, overcoming drug resistance and at the same time potentially reducing side effects. Silk fibroin is a biopolymer that can be processed to obtain biocompatible and biodegradable nanoparticles that can be efficiently loaded by surface adsorption with small-molecule therapeutics and allow their transport and sustained release by modulating their pharmacokinetics. Auranofin (AF) has recently been repurposed for its strong anticancer activity and is currently in clinical trials. Its mechanism of action is through the inhibition of thioredoxin reductase enzymes, which play an essential role in several intracellular processes and are overexpressed in some tumours. Taking into account that AF has a low solubility in water, we propose silk fibroin nanoparticles (SFN) as AF carrier in order to improve its bioavailability, increasing cellular absorption and preventing its degradation or avoiding some resistance mechanisms. Here we report the preparation and characterization of a new formulation of AF-loaded silk fibroin nanoparticles (SFN-AF), its functionalization with FITC for the analysis of cellular uptake, as well as its cytotoxic activity against cell lines of human colorectal cancer (HT29 and HCT116) in both 2D and 3D cell cultures. 3D spheroid models provide a 3D environment which mimics the 3D aspects of CRC observed in vivo and represents an effective 3D environment to screen therapeutics for the treatment of CRC. The loaded nanoparticles showed a spherical morphology with a hydrodynamic diameter of ~ 160nm and good stability in aqueous solution due to their negative surface charges. FESEM-EDX analysis revealed a homogeneous distribution of Au clusters with high electron density on the surface of the nanoparticles. SFN-AF incubated in phosphate buffer at 37°C released 77% of the loaded AF over 10 days, showing an initial burst and then sustained release. Flow cytometry analysis showed that FITC-SFN-AF was efficiently internalized by both cell lines, which was confirmed by confocal microscopy imaging. SFN enhanced the cytotoxicity of AF in 2D cultures in both CRC lines. Promising results were also obtained in 3D culture paving the way for future application of this strategy as a therapy for CRC.

Investigating the Effect of Polypyrrole-Gelatin/Silk Fibroin Hydrogel Mediated Pulsed Electrical Stimulation for Skin Regeneration.

In clinical practice to treat complex injuries, the application of electrical stimulation (ES) directly to the skin complicates the wound. In this work, the effect of a conductive hydrogel mediated electric field on skin regeneration is investigated. Polypyrrole incorporated matrices of gelatin and silk fibroin were prepared by two-step interfacial polymerization. The maximum electrical conductivity of 10-4 S cm-1 was achieved when 200 mM polypyrrole was loaded. Mechanically stable and cytocompatible hydrogels were evidenced to have antioxidant and blood compatible characteristics. Human dermal fibroblast cells responded to pulsed stimulation of 100 or 300 mV mm-1 as observed from the increased expressions of TGFβ1, αSMA, and COLIAI genes. Further, the increase in the αSMA protein expression with the magnitude of electrical stimulation also suggested transdifferentiation of the fibroblast to myofibroblast. Moreover, Raman spectroscopy identified two fingerprint regions (collagen and lipid) to differentiate ES treated and nontreated samples. Therefore, the combination of hydrogels and electrical stimulation has potential therapeutic effects for accelerating the rate of skin regeneration.

Tailoring silk-based covering material with matched mechanical properties for vascular tissue engineering

Vascular covered stents play a significant therapeutic role in cardiovascular diseases. However, the poor compliance and biological inertness of commercial materials cause post-implantation complications. Silk fibroin (SF), as a biomaterial, possesses satisfactory hemocompatibility and tissue compatibility. In this study, we developed a silk film for use in covered stents by employing a layer-by-layer self-assembly strategy with regenerated SF on silk braiding fabric. We investigated the effects on the mechanical properties of the silk films in detail, which were closely correlated with fabric parameters and layer-by-layer self-assembly. The results showed that there was a significant relationship between these factors and both the compliance and mechanical strength. The 1 × 2/90°/100/SF6 film exhibited excellent mechanical properties. Notably, compliance reached 2.6%/100 mmHg, matching that of the human saphenous vein. Thus, this strategy shows promise in developing a novel covered stent, with biocompatible and comprehensive mechanical properties, and significant potential for clinical applications.

Silk Fibroin-Based Multiple-Shape-Memory Organohydrogels.

Organohydrogels (OHGs) are intriguing materials due to their unique composition of both hydrophilic and hydrophobic domains. This antagonistic nature endows the OHGs with several remarkable properties, making them highly versatile for various applications. We present here a simple and inexpensive approach to fabricate silk fibroin (SF)-based OHGs with multistage switching mechanics and viscoelasticity. The continuous hydrophilic phase of the OHG precursor consists of an aqueous SF solution, while the hydrophobic droplet phase consists of a crystallizable n-octadecyl acrylate (C18A) monomer and several long-chain saturated hydrocarbons (HCs) with various chain lengths between 14 and 32 carbon atoms, namely, n-tetradecane, n-octadecane, n-docosane, n-dotriacontane, and 1-docosanol. After the addition of a C18A/HC mixture containing Irgacure photoinitiator into the continuous aqueous SF phase under stirring, a stable oil-in-water emulsion was obtained, which was then photopolymerized at 23 ± 2 °C to obtain nonswelling OHGs with multiple-shape-memory behavior. By changing the chain length and mass proportion of HCs, a series of OHGs with tunable transition temperatures could be obtained, meeting various applications. OHGs containing dimer, trimer, and quadruple combinations of in situ-formed poly(C18A) and HC microinclusions exhibit effective triple- or quintuple-shape memory whose shape-recovery temperatures could be adjusted over a wide range, e.g., between 7 and 70 °C.

Biomimetic bilayer scaffold from Bombyx mori silk materials for small diameter vascular applications in tissue engineering.

Enhancing the biocompatibility and mechanical stability of small diameter vascular scaffolds remain significant challenges. To address this challenge, small-diameter tubular structures were electrospun from silk fibroin (SF) from silk textile industry discarded materials to generate bilayer scaffolds that mimic native blood vessels, but derived from a sustainable natural material resource. The inner layer was obtained by directly dissolving SF in formic acid, while the middle layer (SF-M) was achieved through aqueous concentration of the protein. Structural and biological properties of each layer as well as the bilayer were evaluated. The inner layer exhibited nano-scale fiber diameters and 57.9% crystallinity, and degradation rates comparable with the SF-M layer. The middle layer displayed micrometer-scale fibers diameters with an ultimate extension of about 274%. Both layers presented contact angles suitable for cell growth and cytocompatibility, while the bilayer material displayed an intermediate mechanical response and a reduced enzymatic degradation rate when compared to each individual layer. The bilayer material emulates many of the characteristics of native small-diameter vessels, thereby suggesting further studies towards in vivo opportunities.

3D Printing of Biocompatible and Antibacterial Silica-Silk-Chitosan-Based Hybrid Aerogel Scaffolds Loaded with Propolis.

The aim of this study is to design a therapeutic enhanced three-dimensional (3D) silk fibroin (SF)-based scaffold containing propolis (Ps)-loaded chitosan (CH) nanocarriers. To this aim, we initially synthesized a hybrid gel-based ink by a synergistic sol-gel and self-assembly approach and then processed the resulting gels by microextrusion-based 3D printing followed by supercritical drying to obtain 3D hybrid aerogel scaffolds. Ps was utilized to enhance the final scaffold's bactericidal efficacy and cell responsiveness. For the synthesis of the scaffold, two Ps loading methods (in preprint and postprinting steps) were investigated in order to optimize the Ps drug quantities in the scaffold and maximize the antibacterial properties of scaffold. In the postprinting Ps loading step, the hybrid silica-oxidized SF (SFO)-CH hydrogel ink was 3D printed into a construct with an interconnected porous structure, and then, Ps was loaded into the printed construct. In the preprint loading method, PS was incorporated into the SF and a hydrolyzed silane solution prior to gelation. The morphological studies demonstrate that the addition of Ps encapsulated CH nanoparticles (NPs) into the hydrogel solution improved the porosity of the developed scaffolds. The rheological analysis of the designed gel ink with and without Ps loading and the release kinetics were studied. The antimicrobial results show that the Ps-loaded scaffolds in the postprinting step exhibited superior antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) strains compared to a preprinted Ps-loaded scaffold. Direct and indirect in vitro cytotoxicity tests also confirmed the designed Ps-loaded scaffold biocompatibility toward a mouse fibroblast (L929) cell line. We demonstrated that the scaffold formulated by propolis-loaded chitosan NPs can enhance the migration and proliferation of L929 fibroblast cells. The obtained results prove the promise of the designed 3D printed silica-SFO-CH-Ps scaffolds as a potent 3D scaffold to mediate tissue regeneration but also as an antibacterial highly porous matrix to support wound healing.

Functional silk-protein-based nanocomposites for light-stimulated and highly efficient triboelectric nanogenerators and charge storage devices

Overcoming the formidable challenge of achieving multifunctionality and a seamless bio-interface for triboelectric nanogenerators (TENGs) is a persistent pursuit. Here, a biomaterial-based nanocomposite designed for both energy harvesting and storage is presented. Molybdenum disulfide nanosheets (MoS2-NSs) are securely and uniformly incorporated into silk fibroin (SF). The resulting MoS2-NS/SF TENG, in conjunction with a tribo-negative polymer, exhibits an open-circuit voltage (Voc) of 0.95 kV, an average short-circuit current (Isc) of 2.2 μA, and an output power density of 60 μW/cm2—sufficient to illuminate 40 light-emitting diodes (LEDs). Notably, exposure to light triggers a substantial increase in Vocs by more than 26 %. Additionally, the MoS2-NS/SF nanocomposite enables efficient energy storage, with a frequency-dependent dielectric constant ranging from 28.2 to 2.6. This underscores its potential as a versatile electronic material platform for wearable devices, seamlessly integrating motion sensing, energy harvesting, and charge storage capabilities.

Thermal Shrinking of Biopolymeric Hydrogels for High Resolution 3D Printing of Kidney Tubules

AbstractThe effective replication of microtubular structures in tissue engineering remains a great challenge. In this study, the temperature‐responsive characteristics of poly(N‐isopropylacrylamide) (pNIPAM) to create intricate, high‐resolution tubular structures through a shrinking mechanism is investigated by exploring 2 thermosensitive hydrogels–gelatin methacryloyl (gelMA) and silk fibroin methacryloyl (silkMA)–combined with pNIPAM. Systematic investigations revealed precise control of shrinking behavior at elevated temperatures (33–37 °C) as a function of polymer concentration. The hydrogel sizes reduce by ≈15% from room temperature (RT) to 33 °C and ≈40% from RT to 37 °C for both hydrogel types. The shrinking affects the mechanical properties, increasing the compressive modulus by ≈2.8‐fold for gelMA‐pNIPAM gels and ≈5.1‐fold for silkMA‐pNIPAM gels at 37 °C. Combined with volumetric printing, these materials achieve resolution enhancements of ≈20% for positive features and ≈70% for negative features, enabling the creation of complex, high‐resolution structures within seconds, with open channels (≈50 µm). GelMA‐pNIPAM hydrogels show better cell compatibility compared to silkMA‐pNIPAM hydrogels, promoting cell adhesion and viability. This study demonstrates the thermosensitive hydrogels' capability to engineer intricate, high‐resolution tubular structures with volumetric printing–an efficient route to fabricate microenvironments mimicking native tissues with potential for developing relevant in vitro models.

A facile nanopattern modification of silk fibroin electrospun scaffold and corresponding impact on cell proliferation and osteogenesis

Abstract As a well-known natural protein biomaterial, silk fibroin (SF) has shown broad application prospects in typical biomedical fields. However, the mostly used SF from Bombyx mori silkworm lacks specific cell adhesion sites and other bioactive peptide sequences, and there is still significant room for further improvement of their biological functions. Therefore, it is crucial to develop a facile and effective modification strategy for this widely researched biomaterial. In this study, the SF electrospun scaffold has been chosen as a typical SF biomaterial, and air plasma etching has been adopted as a facile nanopattern modification strategy to promote its biological functions. Results demonstrated that the plasma etching could feasibly and effectively create nano-island-like patterns on the complex surface of SF scaffolds, and the detailed nanopattern features could be easily regulated by adjusting the etching time. In addition, the mesenchymal stem cell responses have illustrated that the nanopattern modification could significantly regulate corresponding cell behaviors. Compared with the non-etched scaffold, the 10 min-etched scaffold (10E scaffold) significantly promoted stem cell proliferation and osteogenic differentiation. Moreover, 10E scaffold has also been confirmed to effectively accelerate vascularization and ectopic osteogenesis in vivo using a rat subcutaneous implantation model. However, the mentioned promoting effects would be weakened or even counteracted with the increase of etching time. In conclusion, this facile modification strategy demonstrated great application potential for promoting cell proliferation and differentiation. Thus, it provided useful guidance to develop excellent SF-based scaffolds suitable for bone and other tissue engineering.

Ciprofloxacin hydrochloride-loaded ocular silk fibroin liposomes: Formulation, characterisation, in vitro cytotoxicity, and antimicrobial activity

Ocular drugs have low absorption because of the unique environment in the eye, making ocular drugs one of the most challenging pharmaceutical initiatives. Liposomes have shown to be a promising ocular drug delivery system over the years because of enhanced drug absorption, biocompatibility, and biodegradability. Utilising a mucoadhesive material alongside liposomes could be a promising strategy to increase the therapeutic efficacy of ocular drugs. The present study aimed to develop a silk fibroin (SF)-coated liposomal formulation as an ocular drug delivery system. Regenerated silk fibroin (a novel biopolymer) was coated on ciprofloxacin hydrochloride-loaded liposomes (CPH-SFLs). Studies were carried out on the morphology, drug encapsulation efficiency, and in vitro drug release. Human corneal epithelial cells (HCEC) were used to examine the cellular adherence and cytotoxicity of CPH-SFLs. CPH-SFLs had an average particle size of 183 ± 3 nm as opposed to 169 ± 4 of blank SFLs. CPH-loaded SFLs lacked the endothermic peak of CPH at 150 °C, indicating that the CPH molecules were trapped in the SF polymeric grid. In the case of the formulations, 25% to 45% of the medicine was released at a relatively fast pace over the course of the first 4 hours and then at a slower rate over the course of the next 12-24 hours. CPH-SFLs demonstrated sustained drug release and high in vitro ocular penetration of CPH. The MTT test was conducted to gauge the viability of HCECs, cell viability was higher than 85%, demonstrating that CPH-SFLs had no adverse effects on HCEC. The observed CPH-SFL adhesions to HCECs were swift and persistent, like the cellular uptake of CPH-SFLs by HCECs. When compared to CPH-solution, the produced formulation CPH-SFLs demonstrated significantly (P<0.0001) greater susceptibility. The studies concluded that SF-coated liposomes could be the most viable ocular drug delivery in comparison to conventional eye drops.

Protective effect of water-soluble nervonic acid micro-powder coated with chitosan oligosaccharide and silk fibroin on hippocampal neuronal HT22 cells

Nervonic acid (NA) is an extremely long chain monounsaturated fatty acid that plays a crucial biological role in brain development and repair. However, its low solubility reduced bioavailability and limited its applications. In this study, spherical water-soluble nervonic acid composite micro-powder (NA-WM) was constructed by layer-by-layer self-assembly technology under electrostatic interaction and hydrogen bond, in which electronegative NA was used as the core material, and electropositive COS (Chitosan oligosaccharide) with neuroprotective properties and electronegative SF (Silk fibroin) with biocompatibility and anti-inflammatory synergism were used as the wall material. In the preparation process, the electronegative NA was first combined with electropositive COS by antisolvent method, and then the electropositive COS-NA complex was encapsulated with electronegative SF to form NA-WM. The optimal preparation conditions were screened and optimized via single-factor and BBD method. Under the optimum conditions, the average particle size of NA-WM was 420 ± 35 nm. The results of TGA (Thermogravimetric), SEM (Scanning electron microscopy), and FTIR (Fourier transform infrared spectroscopy) confirmed that NA-WM had good thermal stability and spherical-defined layer-to-layer structure. Additionally, at pH 1.5, the NA release rate of NA-WM was as high as 89.54 % within 2.5 h. Through measuring the levels of MDA (Malondialdehyde), CAT (Catalase), SOD (Superoxide dismutase), GSH-Px (Glutathione peroxidase), and LDH (Lactate dehydrogenase), as well as flow cytometry and SEM analysis, it was confirmed that NA-WM could protect Aβ1–42-induced HT22 by inhibiting oxidative stress and reducing mitochondrial membrane potential. This study provided data support for the development and application of NA.

Ultralight 3D silk nanofiber scaffolds with enhanced hemostatic properties and biocompatibility for rapid hemostasis

Developing an effective hemostatic material that combines excellent biocompatibility with high blood absorption capacity remains a critical clinical challenge. In this study, ultralight three-dimensional (3D) silk fibroin (SF) scaffolds, composed of continuously interconnected nanofibers, are introduced as a novel hemostatic material. The distinctive fluffy nanofiber architecture endows the scaffolds with a remarkable porosity of 78.9 % and exceptional liquid absorption capacity. The integration of montmorillonite (MMT) further enhances the hemostatic properties of the scaffolds, while SF naturally promotes the intrinsic coagulation pathway. The scaffolds exhibit an impressive blood absorption capacity of 1687.7 %. In vitro evaluations indicate that the SF nanofiber scaffolds exhibit a blood clotting index rate of 24.6 %, a hemolysis ratio of less than 4 %, and outstanding biocompatibility. The blood coagulation time is significantly reduced from 449 s to 230 s. Additionally, the scaffolds show adhesion rates to erythrocytes and platelets of 52 % and 45.9 %, respectively. The nanofiber scaffolds aggregate and activate platelets extensively, accelerating the formation of platelet emboli, which collectively contribute to their superior hemostatic performance. Consequently, these nanofiber scaffolds hold substantial promise as absorbable hemostatic agents for achieving rapid hemostasis in clinical applications.

Fabrication and characterization of an electrospun silk fibroin/gelatin transparent graft material for corneal epithelial regeneration

The damaged corneal epithelial causing loss of vision can be restored by epithelial tissue regeneration through tissue engineering approach that provides an engineered corneal substitute with appropriate properties and nanofibrous architecture. This works reports a polymeric matrix that was derived from silk fibroin (SF) and gelatin (GE) natural polymer blend with optimized composition resembling the structure and function of the native epithelial tissue. SF/GE blend spinning solutions prepared with different volume ratios of SF/GE: 70/30, 50/50, and 30/70 were used to fabricate electrospun mats. The fabricated two-dimensional mats had nanofibrous porous architecture having interconnected pores with pore size range of 175–267 nm suitable for corneal epithelial regeneration and 891.2–558 nm fiber diameter range as revealed by scanning electron microscopic image analysis. The performed Fourier transform infrared spectra confirmed the presence of individual polymers in the scaffolds and the scaffolds are hydrophilic in nature. Among the scaffolds, SF/GE 70:30 and SF/GE 50:50 composition possess desired porosity range of 87–88%. The tensile strength was slightly decreased with increase in GE content and the strength obtained was in the range 2.74–2.26 Mpa. An enhanced transparency was obtained with increased GE concentration, the transparency range of 73–82% observed with SF/GE:50/50 matches with the transparency of natural corneal epithelium. The biocompatibility of the scaffolds was confirmed by cell attachment, cytotoxicity and ROS evaluation by culturing rabbit corneal fibroblast cells (SIRC) on the scaffolds. Among the scaffolds, SF/GE: 70/30 exhibited the highest cell viability, but with less transparency ranging 55–71%. Therefore, considering all the properties, SF/GE with 50:50 ratio scaffold may be a suitable substrate in the field of corneal tissue engineering.

Investigation of the cushioning mechanism of a novel dental implant system with composite hydrogel

Background/purposeDental implants can restore both function and aesthetics in edentulous areas. However, the absence of cushioning mechanical behavior in implants may limit their clinical performance and reduce the long-term survival rates. This study aimed to establish an implant cushion mechanism that mimicked the natural periodontal ligament, utilizing the properties of composite hydrogels. Materials and methodsIn this study, we synthesized two composite hydrogels (HS and HSP groups) using hyaluronic acid (HA) and silk fibroin. We conducted static-constrained compression, creep, and porosity tests to assess the physical properties of these composite hydrogels. Finite element analysis (FEA) was employed to examine the effects of different thicknesses, permeabilities, and compression coefficients on the deformation of the hydrogels. The composite hydrogels were then applied within a novel dental implant, and the displacement performance of the implants, along with stress distribution on the alveolar bone, was evaluated using FEA. ResultsRegarding the mechanical performance of the composite hydrogels, increased permeability led to quicker displacement under compression. Thicker hydrogels with larger compression moduli influenced the biphasic behavior and deformation. The novel dental implants demonstrated biphasic sinking behavior under loading and rapid repositioning during unloading. When evaluating stress distribution on the alveolar bone under oblique loading, the HS and HSP implant groups showed a stress reduction of 10.3 % and 13.6 %, respectively, compared to commercial implant groups. ConclusionThis study highlights that the biphasic nature of solid and liquid phases is crucial when incorporating a cushioning mechanism into implants to replicate the characteristics of the periodontal ligament.