Multi-Responsive Silk Fibroin-Based Nanoparticles for Drug Delivery

Drug repurposing for cancer therapy

Cancer, a complex and multifactorial disease, presents a significant challenge to global health. Despite significant advances in surgical, radiotherapeutic and immunological approaches, which have improved cancer treatment outcomes, drug therapy continues to serve as a key therapeutic strategy. However, the clinical efficacy of drug therapy is often constrained by drug resistance and severe toxic side effects, and thus there remains a critical need to develop novel cancer therapeutics. One promising strategy that has received widespread attention in recent years is drug repurposing: the identification of new applications for existing, clinically approved drugs. Drug repurposing possesses several inherent advantages in the context of cancer treatment since repurposed drugs are typically cost-effective, proven to be safe, and can significantly expedite the drug development process due to their already established safety profiles. In light of this, the present review offers a comprehensive overview of the various methods employed in drug repurposing, specifically focusing on the repurposing of drugs to treat cancer. We describe the antitumor properties of candidate drugs, and discuss in detail how they target both the hallmarks of cancer in tumor cells and the surrounding tumor microenvironment. In addition, we examine the innovative strategy of integrating drug repurposing with nanotechnology to enhance topical drug delivery. We also emphasize the critical role that repurposed drugs can play when used as part of a combination therapy regimen. To conclude, we outline the challenges associated with repurposing drugs and consider the future prospects of these repurposed drugs transitioning into clinical application.

Advancements in Hybrid Cellulose-Based Films: Innovations and Applications in 2D Nano-Delivery Systems

This review paper delves into the realm of hybrid cellulose-based materials and their applications in 2D nano-delivery systems. Cellulose, recognized for its biocompatibility, versatility, and renewability, serves as the core matrix for these nanomaterials. The paper offers a comprehensive overview of the latest advancements in the creation, analysis, and application of these materials, emphasizing their significance in nanotechnology and biomedical domains. It further illuminates the integration of nanomaterials and advanced synthesis techniques that have significantly improved the mechanical, chemical, and biological properties of hybrid cellulose-based materials.

Sustainable Bombyx mori's silk fibroin for biomedical applications as a molecular biotechnology challenge: A review

Silk is a natural engineering material with a unique set of properties. The major constituent of silk is fibroin, a protein widely used in the biomedical field because of its mechanical strength, toughness and elasticity, as well as its biocompatibility and biodegradability. The domestication of silkworms allows large amounts of fibroin to be extracted inexpensively from silk cocoons. However, the industrial extraction process has drawbacks in terms of sustainability and the quality of the final medical product. The heterologous production of fibroin using recombinant DNA technology is a promising approach to address these issues, but the production of such recombinant proteins is challenging and further optimization is required due to the large size and repetitive structure of fibroin's DNA and amino acid sequence. In this review, we describe the structure-function relationship of fibroin, the current extraction process, and some insights into the sustainability of silk production for biomedical applications. We focus on recent advances in molecular biotechnology underpinning the production of recombinant fibroin, working toward a standardized, successful and sustainable process.

Silk Fibroin Encapsulated Icariin Nanoparticles Mitigate Bisphenol A-Induced Spermatogenesis Dysfunction

Bisphenol A (BPA) is a prevalent endocrine disruptor found in natural environments. Exposure to BPA has been associated with male infertility. The natural phytochemical icariin (ICA) has demonstrated significant promise for the treatment of male infertility. However, its effectiveness is limited due to its low bioavailability, poor water solubility, and insufficient targeting abilities. Herein, novel nanoparticles are generated from the natural silk fibroin, which are used to load ICA. The efficient drug delivery system (ICA-SNPs) result in significantly focused drug distribution to spermatogonium, enhancing the anti-infertility properties of ICA, and can effectively mitigate spermatogenesis dysfunction induced by BPA, control serum sex hormone levels, and enhance testicular ultrastructure. Additionally, the ICA-SNPs restore spermatogenesis dysfunction primarily via the hormone biosynthesis, spermatogonium meiosis process, and glycerophospholipid metabolism.

Applications and Potentials of a Silk Fibroin Nanoparticle Delivery System in Animal Husbandry

Silk fibroin (SF), a unique natural polymeric fibrous protein extracted from Bombyx mori cocoons, accounts for approximately 75% of the total mass of silk. It has great application prospects due to its outstanding biocompatibility, biodegradability, low immunogenicity, and mechanical stability. Additionally, it is non-toxic and environmentally friendly. Nanoparticle delivery systems constructed with SF can improve the bioavailability of the carriers, increase the loading rates, control the release behavior of the deliverables, and enhance their action efficiencies. Animal husbandry is an integral part of agriculture and plays a vital role in the development of the rural economy. However, the pillar industry experiences a lot of difficulties, like drug abuse while treating major animal diseases, and serious environmental pollution, restricting sustainable development. Interestingly, the limited use cases of silk fibroin nanoparticle (SF NP) delivery systems in animal husbandry, such as veterinary vaccines and feed additives, have shown great promise. This paper first reviews the SF NP delivery system with regard to its advantages, disadvantages, and applications. Moreover, we describe the application status and developmental prospects of SF NP delivery systems to provide theoretical references for further development in livestock production and promote the high-quality and healthy development of animal husbandry.

Colorimetric Properties of Bombyx mori Silk Fibroin

Recent reports highlighted several novel applications for the Bombyx mori silk fibroin (SF), as edible coatings for the preservation of food freshness, smart labels, or packaging materials. This study complements these reports and additionally describes the colorimetric sensing properties of the natural protein that could be explored to enhance the practical value of such applications. Our data show that in response to pH changes, reconstituted SF is able to undergo visible color changes that correlate with the intensity of the stimuli, regardless of its physical format or physical cross-linking state. The intensity of the developed color was proportional to the extent of the protein's hydrolytic degradation. We also found that these pH-driven color changes were reversible and interchangeable, with colorless samples at neutral pH, purple in acidic environments, and yellow under basic conditions. Our mechanistic studies identified tryptophan as being responsible for these colorimetric responses, which could be further intensified by the presence of ionized tyrosine functionalities. In addition, we determined that SF's sensing properties also applied to ultraviolet light exposure. Finally, we showed that the innate sensing capabilities of activated SF can be enhanced via the covalent incorporation of additional tryptophan into the protein. Overall, our results further support the utility of SF for sensing applications.

Protein-based Nanoparticles: From Drug Delivery to Imaging, Nanocatalysis and Protein Therapy

Proteins and enzymes are versatile biomaterials for a wide range of medical applications due to their high specificity for receptors and substrates, high degradability, low toxicity, and overall good biocompatibility. Protein nanoparticles are formed by the arrangement of several native or modified proteins into nanometer-sized assemblies. In this review, we will focus on artificial nanoparticle systems, where proteins are the main structural element and not just an encapsulated payload. While under natural conditions, only certain proteins form defined aggregates and nanoparticles, chemical modifications or a change in the physical environment can further extend the pool of available building blocks. This allows the assembly of many globular proteins and even enzymes. These advances in preparation methods led to the emergence of new generations of nanosystems that extend beyond transport vehicles to diverse applications, from multifunctional drug delivery to imaging, nanocatalysis and protein therapy.

A Convergent fabrication of silk fibroin nanoparticles on quercetin loaded metal-organic frameworks for promising nanocarrier of myocardial infraction

The biomacromolecule silk fibroin (SF) may be constructed to promote biomimetic nucleation and nanostructures of inorganic nanomaterials, offering it a promising candidate for use in various biomimetic applications. We combined SF-NPs and ZIF-8-NPs to fabricate new drug vehicles that effectively release the drug. SF nanoparticles (SF-NPs) were assembled into quercetin (QCT), a myocardial drug added to fabricate QSF-NPs. By acting as a template for the ZIF-8 nucleation onto the surface, the QSF-NPs fabricated core-shell-structured nanocomposites (named QSF@Z-NCs) with ZIF-8 as the core-shell and the QSF-NPs. The biocompatibility analysis using the MTT assay revealed that the developed QCT, SF-NPs, and QSF@Z-NCs are not harmful to cardiac myoblast (H9C2) cells. The in vivo model demonstrated that H9C2 cells encouraged cardiomyocyte fibre regeneration in myocardial infarction rats. We fabricated a brand-new technique using H9C2 cells and QSF@Z-NCs that might encourage the healing processes in myocardial ischemia cells. This study's results demonstrate that it successfully treats myocardial injury.

Effect of silk fibroin scaffold loaded with 17-β estradiol on the proliferation and differentiation of BMSCs

In this study, different concentrations of 17-β estradiol silk fibroin (SF)porous scaffolds (SFPS) were prepared using freeze-drying technique, with a hope for optimal concentration and apply it locally to the bone defect area. In this study, the porous scaffold morphology structure was characterized by SEM, FTIR and universal capacity testing machines, and the in vitro cytocompatibility and biological activity of scaffold materials were studied by cell adhesion, viability and proliferation experiments. The results showed that SFPS boasts better physicochemical properties, while 17-β estradiol SF scaffolds with low concentrations of 10-10 mol/L and 10-12 mol/L had more growth and proliferation of SF scaffolds with higher concentrations, and 10-10 mol/L was the optimal concentration of 17-β estradiol SFPS, which was more conducive to cell adhesion and proliferation. On the other hand, after osteogenesis induction of BMSCs inoculated on 17-β estradiol SFPS at different concentrations, it was found that the expression of alkaline phosphatase in BMSCs on different concentrations of 17-β estradiol porous scaffolds was not large. No conflict of interest exits in the submission of this manuscript.

Innovative Approaches and Advances for Hair Follicle Regeneration

Pathological hair loss (also known as alopecia) and shortage of hair follicle (HF) donors have posed an urgent requirement for HF regeneration. With the revelation of mechanisms in tissue engineering, the proliferation of HFs in vitro has achieved more promising trust for the treatments of alopecia and other skin impairments. Theoretically, HF organoids have great potential to develop into native HFs and attachments such as sweat glands after transplantation. However, since the rich extracellular matrix (ECM) deficiency, the induction characteristics of skin-derived cells gradually fade away along with their trichogenic capacity after continuous cell passaging in vitro. Therefore, ECM-mimicking support is an essential prelude before HF transplantation is implemented. This review summarizes the status of providing various epidermal and dermal cells with a three-dimensional (3D) scaffold to support the cell homeostasis and better mimic in vivo environments for the sake of HF regeneration. HF-relevant cells including dermal papilla cells (DPCs), hair follicle stem cells (HFSCs), and mesenchymal stem cells (MSCs) are able to be induced to form HF organoids in the vitro culture system. The niche microenvironment simulated by different forms of biomaterial scaffold can offer the cells a network of ordered growth environment to alleviate inductivity loss and promote the expression of functional proteins. The scaffolds often play the role of ECM substrates and bring about epithelial-mesenchymal interaction (EMI) through coculture to ensure the functional preservation of HF cells during in vitro passage. Functional HF organoids can be formed either before or after transplantation into the dermis layer. Here, we review and emphasize the importance of 3D culture in HF regeneration in vitro. Finally, the latest progress in treatment trials and critical analysis of the properties and benefits of different emerging biomaterials for HF regeneration along with the main challenges and prospects of HF regenerative approaches are discussed.

Optimizing the Preparation of Silk Fibroin Nanoparticles and Their Loading with Polyphenols: Towards a More Efficient Anti-Inflammatory Effect on Macrophages

Silk fibroin nanoparticles (SFN) have become a promising tool in drug delivery systems due to their physicochemical characteristics. SFN have shown their outstanding properties as an active vehicle for polyphenols, enhancing their antioxidant and anti-inflammatory effects on macrophages; therefore, it becomes necessary to have an easy, reproducible and scalable production method. In order to improve the production of nanoparticles, we performed direct precipitation of non-dialyzed silk fibroin solutions and evaluated the reproducibility of the method using dynamic light scattering. We also studied the loading efficiency of three different natural polyphenols using propylene glycol as a solvent. The loaded nanoparticles were fully characterized and used to treat human macrophage cells to assess the anti-inflammatory activity of these nanoparticles. The measured hydrodynamic characteristics of the SFN and the overall yield of the process showed that the new preparation method is highly reproducible and repeatable. Thus, we not only present a new scalable method to prepare silk nanoparticles but also how to improve the loading of natural polyphenolic compounds to the SFN, as well as the important anti-inflammatory effects of these loaded nanoparticles in a cell model of human macrophage cells.

Research progress of natural silk fibroin and the appplication for drug delivery in chemotherapies

Silk fibroin has been widely used in biological fields due to its biocompatibility, mechanical properties, biodegradability, and safety. Recently, silk fibroin as a drug carrier was developed rapidly and achieved remarkable progress in cancer treatment. The silk fibroin-based delivery system could effectively kill tumor cells without significant side effects and drug resistance. However, few studies have been reported on silk fibroin delivery systems for antitumor therapy. The advancement of silk fibroin-based drug delivery systems research and its applications in cancer therapy are highlighted in this study. The properties, applications, private opinions, and future prospects of silk fibroin carriers are discussed to understand better the development of anti-cancer drug delivery systems, which may also contribute to advancing silk fibroin innovation.

Silk Fibroin as an Efficient Biomaterial for Drug Delivery, Gene Therapy, and Wound Healing

Silk fibroin (SF), an organic material obtained from the cocoons of a silkworm Bombyx mori, is used in several applications and has a proven track record in biomedicine owing to its superior compatibility with the human body, superb mechanical characteristics, and its controllable propensity to decay. Due to its robust biocompatibility, less immunogenic, non-toxic, non-carcinogenic, and biodegradable properties, it has been widely used in biological and biomedical fields, including wound healing. The key strategies for building diverse SF-based drug delivery systems are discussed in this review, as well as the most recent ways for developing functionalized SF for controlled or redirected medicines, gene therapy, and wound healing. Understanding the features of SF and the various ways to manipulate its physicochemical and mechanical properties enables the development of more effective drug delivery devices. Drugs are encapsulated in SF-based drug delivery systems to extend their shelf life and control their release, allowing them to travel further across the bloodstream and thus extend their range of operation. Furthermore, due to their tunable properties, SF-based drug delivery systems open up new possibilities for drug delivery, gene therapy, and wound healing.

Efficient Tumor Immunotherapy through a Single Injection of Injectable Antigen/Adjuvant-Loaded Macroporous Silk Fibroin Microspheres

Synthetic or natural materials have been used as vaccines in cancer immunotherapy. However, using them as vaccines necessitates multiple injections or surgical implantations. To tackle such daunting challenges, we develop an injectable macroporous Bombyx mori (B. mori) silk fibroin (SF) microsphere loaded with antigens and immune adjuvants to suppress established tumors with only a single injection. SF microspheres can serve as a scaffold by injection and avoid surgical injury as seen in traditional scaffold vaccines. The macroporous structure of the vaccine facilitates the recruitment of immune cells and promotes the activation of dendritic cells (DCs), resulting in a favorable immune microenvironment that further induces strong humoral and cellular immunity. We have also modified the vaccine into a booster version by simply allowing the antigens to be adsorbed onto the SF microspheres. The booster vaccine highly efficiently suppresses tumor growth by improving the cytotoxic T lymphocyte (CTL) response. In general, these results demonstrate that the macroporous SF microspheres can serve as a facile platform for tumor vaccine therapy in the future. Since the SF microspheres are also potential scaffolds for tissue regeneration, their use as a vaccine platform will enable their applications in eradicating tumors while regenerating healthy tissue to heal the tumor-site cavity.

Baicalein-loaded silk fibroin peptide nanofibers protect against cisplatin-induced acute kidney injury: fabrication, characterization and mechanism

Silk fibroin (SF) is a natural polymeric biomaterial widely used in the preparation of drug delivery systems. Herein, silk fibroin peptide (SFP) was self-assembled into nanofibers, encapsulated a poorly water-soluble drug baicalein (SFP/BA NFs), and then used to protect against cisplatin-induced acute kidney injury (AKI). Specifically, the SFP/BA NFs significantly enhanced the aqueous dispersity, storage stability, and in vitro antioxidant activity of BA. SFP/BA NFs increased the drug uptake and localization to mitochondria. In vitro results demonstrated that SFP/BA NFs can relieve the cisplatin-induced HK-2 cell damage, and inhibit the cisplatin-induced accumulation of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) disruption. Mechanism studies demonstrated that SFP/BA NFs may exert nephroprotective effects by inhibiting both the cisplatin-induced DNA damage and the cGAS/STING pathway activation. In vivo results showed that cisplatin treatment resulted in decreased body weight, increased serum creatinine (SCr), and increased blood urea nitrogen (BUN) levels, while SFP/BA NFs reversed the above symptoms. Furthermore, SFP/BA NFs reversed the cisplatin-induced abnormal changes of antioxidant enzymes (e.g., SOD and GSH), and inhibited the cisplatin-induced DNA damage as well as the activation of cGAS/TING. Above all, our results revealed the potential of SFP/BA NFs to protect against cisplatin-induced AKI.

Silk Fibroin as a Bioink - A Thematic Review of Functionalization Strategies for Bioprinting Applications

Bioprinting is an emerging tissue engineering technique that has attracted the attention of researchers around the world, for its ability to create tissue constructs that recapitulate physiological function. While the technique has been receiving hype, there are still limitations to the use of bioprinting in practical applications, much of which is due to inappropriate bioink design that is unable to recapitulate complex tissue architecture. Silk fibroin (SF) is an exciting and promising bioink candidate that has been increasingly popular in bioprinting applications because of its processability, biodegradability, and biocompatibility properties. However, due to its lack of optimum gelation properties, functionalization strategies need to be employed so that SF can be effectively used in bioprinting applications. These functionalization strategies are processing methods which allow SF to be compatible with specific bioprinting techniques. Previous literature reviews of SF as a bioink mainly focus on discussing different methods to functionalize SF as a bioink, while a comprehensive review on categorizing SF functional methods according to their potential applications is missing. This paper seeks to discuss and compartmentalize the different strategies used to functionalize SF for bioprinting and categorize the strategies for each bioprinting method (namely, inkjet, extrusion, and light-based bioprinting). By compartmentalizing the various strategies for each printing method, the paper illustrates how each strategy is better suited for a target tissue application. The paper will also discuss applications of SF bioinks in regenerating various tissue types and the challenges and future trends that SF can take in its role as a bioink material.

The Contribution of Silk Fibroin in Biomedical Engineering

Silk fibroin (SF) is a natural protein (biopolymer) extracted from the cocoons of Bombyx mori L. (silkworm). It has many properties of interest in the field of biotechnology, the most important being biodegradability, biocompatibility and robust mechanical strength with high tensile strength. SF is usually dissolved in water-based solvents and can be easily reconstructed into a variety of material formats, including films, mats, hydrogels, and sponges, by various fabrication techniques (spin coating, electrospinning, freeze-drying, and physical or chemical crosslinking). Furthermore, SF is a feasible material used in many biomedical applications, including tissue engineering (3D scaffolds, wounds dressing), cancer therapy (mimicking the tumor microenvironment), controlled drug delivery (SF-based complexes), and bone, eye and skin regeneration. In this review, we describe the structure, composition, general properties, and structure-properties relationship of SF. In addition, the main methods used for ecological extraction and processing of SF that make it a green material are discussed. Lastly, technological advances in the use of SF-based materials are addressed, especially in healthcare applications such as tissue engineering and cancer therapeutics.

Sirolimus Release from Biodegradable Polymers for Coronary Stent Application: A Review

Drug-eluting stents (DESs) are commonly used for the treatment of coronary artery disease. The evolution of the drug-eluting layer on the surface of the metal stent plays an important role in DES functionality. Here, the use of biodegradable polymers has emerged as an attractive strategy because it minimizes the occurrence of late thrombosis after stent implantation. Furthermore, understanding the drug-release behavior of DESs is also important for improving the safety and efficacy of stent treatments. Drug release from biodegradable polymers has attracted extensive research attention because biodegradable polymers with different properties show different drug-release behaviors. Molecular weight, composition, glass transition temperature, crystallinity, and the degradation rate are important properties affecting the behavior of polymers. Sirolimus is a conventional anti-proliferation drug and is the most widely used drug in DESs. Sirolimus-release behavior affects endothelialization and thrombosis formation after DES implantation. In this review, we focus on sirolimus release from biodegradable polymers, including synthetic and natural polymers widely used in the medical field. We hope this review will provide valuable up-to-date information on this subject and contribute to the further development of safe and efficient DESs.

Combining nanotechnology with the multifunctional roles of neutrophils against cancer and inflammatory disease

Neutrophils, the most abundant leukocytes in humans, play a crucial role in acute inflammation during infection and tumorigenesis. Neutrophils are the major types of cells recruited to the inflammation sites induced by pathogens, exhibiting great homing ability towards inflammatory disorders and tumor sites. Therefore, a neutrophil-based drug delivery system (NDDS) has become a promising platform for anti-cancer and anti-inflammatory treatment. Recent decades have witnessed the huge progress of applying nanomaterials in drug delivery. Nanomaterials are regarded as innovative components to enrich the field of neutrophil-based therapies due to their unique physiochemical characteristics. In this review, the latest advancement of combining diverse nanomaterials with an NDDS for cancer and inflammatory disease treatment will be summarized. It is discussed how nanomaterials empower the therapeutic area of an NDDS and how an NDDS circumvents the limitations of nanomaterials. Moreover, based on the finding that neutrophils are closely involved in the progression of cancer and inflammatory diseases, emerging therapeutic strategies that target neutrophils will be outlined. Finally, as neutrophils were demonstrated to play a central role in the immunopathology of COVID-19, which causes necroinflammation that is responsible for the cytokine storm and sepsis during coronavirus infections, novel therapeutic approaches that anchor neutrophils against the pathological consequences related to COVID-19 will be highlighted as well.

Silk fibroin-capped metal-organic framework for tumor-specific redox dyshomeostasis treatment synergized by deoxygenation-driven chemotherapy

Disturbance in redox homeostasis always leads to oxidative damages to cellular components, which inhibits cancer cell proliferation and causes tumor regression. Therefore, synergistic effects arising from cellular redox imbalance together with other treatment modalities are worth further investigation. Herein, a metal-organic framework nanosystem (NMOF) based on coordination between Fe (III) and 4,4,4,4-(porphine-5,10,15,20-tetrayl) tetrakis (benzoic acid) (TCPP) was synthesized through a one-pot method. After surface capping of silk fibroin (SF) to form NMOF@SF nanoparticles (NPs), this nanoplatform can serve as an eligible nanocarrier to deliver tirapazamine (TPZ), a hypoxia-activated precursor. As-developed NS@TPZ (NST) NPs remained inactive in the normal tissue, whereas became highly active upon endocytosis by tumor cells via glutathione (GSH)-mediated reduction of Fe (III) into Fe (II), further enabling Fe (II)-mediated chemodynamic therapy (CDT). Upon optical laser irradiation, TCPP-mediated photodynamic therapy (PDT) coordinated with CDT to aggravate intracellular oxidative stress. Thus, such reactive oxygen species accumulation and GSH deprivation contributed to a deleterious redox dyshomeostasis. On the other hand, local deoxygenation caused by PDT can increase the cytotoxicity of released TPZ, which significantly improved the integral therapeutic effectiveness relying on the combined redox balance disruption and bioreductive chemotherapy. More importantly, severe immunogenic cell death can be triggered by the combinatorial treatment modalities and the presence of SF, which facilitated an almost complete tumor eradication in vivo. Taken together, this paradigm provides an insightful strategy for tumor-specific redox dyshomeostasis treatment synergized by deoxygenation-driven chemotherapy, which can remarkably enhance antitumor efficacy with negligible adverse effects. STATEMENT OF SIGNIFICANCE: Recently, silk fibroin (SF) has been demonstrated to be effective in activating antitumor immune system through polarization tumor-associated macrophages into M1 subtype. However, engineering SF into multifunctional nanocomposites is seldom reported for combination tumor therapy. In another aspect, disruption of redox homeostasis becomes increasingly attractive for tumor suppression with high clinical-relevance. Herein, we established a newfashioned NMOF nanosystem, named as NST, for tumor-specific redox dyshomeostasis treatment synergized by deoxygenation-driven chemotherapy. This platform takes advantages of Fe²⁺/Fe³⁺ coupled Fenton-like reaction and GSH depletion, as well as TCPP-mediated photosensitization for admirable redox unbalancing, which further initiates hypoxia-relevant toxin of TPZ for chemotherapy. Finally, combinatorial treatments and the presence of SF could trigger ICD for rendering a complete tumor eradication in vivo.

MnO2-capped silk fibroin (SF) nanoparticles with chlorin e6 (Ce6) encapsulation for augmented photo-driven therapy by modulating the tumor microenvironment

Silk fibroin (SF), derived from Bombyx mori, is a category of fibrous protein with outstanding potential for applications in the biomedical and biotechnological fields. In spite of its many advantageous properties, the exploration of SF as a versatile nanodrug precursor for tumor therapy has still been restricted in recent years. Herein, a multifunctional SF-derived nanoplatform was facilely developed via encapsulating the photosensitizer chlorin e6 (Ce6) into MnO2-capped SF nanoparticles (NPs). SF@MnO2 nanocarriers were synthesized through a surface crystallization technique, using SF as a reductant and sacrificial template. Afterwards, Ce6 was covalently incorporated into the loose structure of the SF@MnO2 nanocarrier on the basis of adsorption to abundant peptide-binding sites. To modulate the tumor microenvironment (TME), SF@MnO2/Ce6 (SMC) NPs were capable of catalyzing the decomposition of H2O2 into O2, which can be converted into cytotoxic reactive oxygen species (ROS) during photodynamic therapy (PDT). Moreover, the MnO2 component was able to oxidize intracellular glutathione (GSH) into non-reducing glutathione disulfide (GSSG), and the consumption of GSH could significantly protect the local ROS from being reduced, which further augmented the therapeutic outcome of PDT. Via another angle, SMC NPs can produce strong hyperthermia under near-infrared (NIR) light activation, which was highly desirable for efficient photothermal therapy (PTT). Both in vitro and in vivo studies demonstrated the intense tumor inhibitory effects as a result of augmented PTT/PDT mediated by SMC NPs. We believe that this study may provide useful insights for employing SF-based nanocomposites for more medical applications in the near future.

Silk fibroin nanoparticles enhance quercetin immunomodulatory properties in DSS-induced mouse colitis

Inflammatory bowel disease (IBD) is a chronic and idiopathic inflammatory disorder affecting the gastrointestinal tract. The pharmacological treatments used currently for its treatment lack efficacy, so new therapeutic strategies should be developed. In this context, flavonoids loaded in biopolymeric nanoparticles can be considered as novel promising candidates. The aim of the present study was to evaluate the intestinal anti-inflammatory effects of quercetin when is administered loaded in silk fibroin nanoparticles (QSFN) in the dextran sulphate sodium experimental model of mouse colitis, which displays some similarities to human IBD. Previously characterized quercetin-loaded silk fibroin nanoparticles (QSFN). QSFN showed a reversible aggregation profile induced by the acidification of the solution but did not affect the loaded quercetin. Daily administration of QSFN significantly reduced disease activity index values compared to the control colitic group. This beneficial effect was not only corroborated by the histological examination of the colonic specimens but also the improvement of the colonic expression of the different proinflammatory cytokines (Tnf-α, Il-1β, Il-6, Mcp-1, Icam-1, Nlrp3 and iNOS). Therefore, these data suggest that QSFN could be a promising alternative to current treatments as a drug delivery system for IBD treatment.

Polydopamine-assisted immobilization of silk fibroin and its derived peptide on chemically oxidized titanium to enhance biological activity in vitro

Biochemical modification can endow the surface of implants with superior biological activity. Herein, silk fibroin (SF) protein and its anionic derivative peptides (Cs) were covalently immobilized onto a titanium implant surface via a polydopamine layer. The successful conjugation of SF and Cs was revealed by X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and contact angle measurements. The addition of Cs prevented the conformational transition of silk fibroin to silk II. The deposition of apatite on its surface was significantly accelerated, and the bioactive composite coating was observed to enhance protein adsorption and cell proliferation. More importantly, it also promoted the osteogenic differentiation of bone marrow stem cells (BMSCs) for the quantitative and qualitative detection of alkaline phosphatase (ALP) and alizarin red (ARS). Overall, the stable performance and enhanced osteogenic property of the composite coating promote an extensive application for clinical titanium-based implants.

Emerging Silk Material Trends: Repurposing, Phase Separation and Solution-Based Designs

Silk continues to amaze. This review unravels the most recent progress in silk science, spanning from fundamental insights to medical silks. Key advances in silk flow are examined, with specific reference to the role of metal ions in switching silk from a storage to a spinning state. Orthogonal thermoplastic silk molding is described, as is the transfer of silk flow principles for the triggering of flow-induced crystallization in other non-silk polymers. Other exciting new developments include silk-inspired liquid-liquid phase separation for non-canonical fiber formation and the creation of "silk organelles" in live cells. This review closes by examining the role of silk fabrics in fashioning facemasks in response to the SARS-CoV-2 pandemic.