Silk-based delivery systems of bioactive molecules

Multifunctional applications of silk fibroin in biomedical engineering: A comprehensive review on innovations and impact

Silk fibroin (SF) is a biomaterial naturally produced by certain insects (notably silkworms), animals such as spiders, or through recombinant methods in genetically modified organisms. Its exceptional mechanical properties, biocompatibility, degradability, and bioactivity have inspired extensive research. In biomedicine, SF has been utilized in various forms, including gels, membranes, microspheres, and more. It also demonstrates versatility for applications across medical devices, regenerative medicine, tissue engineering, and related fields. This review explores the current research status, advantages, limitations, and potential application pathways of SF in biomedical engineering. The objective is to stimulate innovative ideas and perspectives for research and applications involving silk.

High-yield spidroin mimics for bioinspired fibers via computational design

The exceptional mechanical properties, biocompatibility, and biodegradability of spider silk make it a promising biomaterial, yet large-scale production remains hindered by challenges in heterologous expression. Existing prokaryotic systems face bottlenecks due to spidroins' high molecular weight, repetitive sequences, and GC-rich motifs, leading to low yields, premature transcription termination, and insoluble inclusion bodies. Addressing these challenges, the study integrates deep learning and bioengineering to design water-soluble, β-sheet-rich spidroin mimics optimized for efficient prokaryotic expression. By replacing polyalanine motifs in Nephila clavipes MaSp1 with computationally screened sequences (e.g., ITVQQ from Burkholderia OspA), five functional spidroins were engineered and solubly expressed in E. coli, achieving yields up to 0.99 g/L. Circular dichroism revealed that modified spidroins (e.g., 3rep-ITVQQ) exhibited β-sheet content up to 81.3% under thermal induction, surpassing unmodified MaSp1 (41.5%). Structural analysis via SEM demonstrated dense, uniform networks in 3rep-ITVQQ, correlating with enhanced mechanical potential. And 24rep-ITVQQ nanofibers were successfully prepared by electrostatic spinning. Coarse-grained molecular dynamics simulations validated progressive self-assembly with reduced solvent-accessible surface area over 1,000 ns. This work bridges the gap between sequence design and scalable production by overcoming expression barriers, simplifying purification, and leveraging β-sheet stacking for tunable mechanical properties. The results provide a blueprint for high-performance biomimetic fibers, advancing applications (e.g., surgical sutures, scaffolds) in tissue engineering and functional materials while addressing the limitations of conventional spidroin production systems.

A critical view of silk fibroin for non-viral gene therapy

Exogenous genes are inserted into target cells during gene therapy in order to compensate or rectify disorders brought on by faulty or aberrant genes. However, gene therapy is still in its early stages because of its unsatisfactory therapeutic effects which are mainly due to low transfection efficiency of vectors, high toxicity, and poor target specificity. A natural polymer with numerous bioactive sites, good mechanical qualities, biodegradability, biocompatibility, and processability called silk fibroin has gained attention as a possible gene therapy vector. Using silk fibroin as a gene vector can reduce cell toxicity, extend the duration of gene expression, and allow further release even in the bloodstream, thereby expanding its therapeutic scope. This review outlines the advancements made with regard to gene delivery methods based on silk fibroin materials in the fields of malignant tumors, bone tissue regeneration, neural tissue, and vascular tissue engineering. Silk fibroin exhibits remarkable repair and therapeutic effects in gene therapy and can be employed in numerous forms, such as a vector (nanoparticles, microcapsules) or a matrix (hydrogel, scaffold) for gene delivery.

Delivery of Polypeptide Drugs Using Nanoparticles Made of Recombinant Spider Silks Derived From MaSp4 Protein

Background

Spider silk protein is a biocompatible and biodegradable protein that can self-assemble into various morphological materials for biomedical applications including drug delivery carriers. Spiders can spin up to seven types of silk fibers, each containing multiple silk proteins. Despite the numerous potential applications of these silk proteins, comprehensive and in-depth research on their specific roles and efficacy in drug delivery has yet to be conducted. The authors designed three new bioengineered spider silk proteins (M4R2, M4R4, and M4R6) and examined its property as a carrier of polypeptided drugs.

Materials and Methods

To obtain the M4R2, M4R4, and M4R6 proteins, three constructs comprising 2, 4, and 6 repeat units of Araneus ventricosus major ampullate spidroin 4 (MaSp4) were engineered for prokaryotic expression using the Escherichia coli expression system. The particles made of M4R2, M4R4, and M4R6 silks were produced using a high concentration of potassium phosphate buffer. The physical properties of these particles were characterized by scanning electron microscopy (SEM) and zeta potential analysis. The cytotoxicity of particles was analyzed using MTT assay. The loading and release profiles of drugs were examined spectrophotometrically.

Results

The three bioengineered silk proteins, M4R2, M4R4, and M4R6, were constructed, produced, and purified. These proteins exhibit self-assembly properties and formed particles. Furthermore, the these particles were not cytotoxic and had similar particle sizes but differed in loading efficiency and drug release rate. The loading of drugs into the M4R2 particles was more efficient (>95%) than that into the M4R4 and M4R6 particles. In addition, the continuous release of ChMAP-28 from M4R2 particles over 30 days indicates its potential as a sustained-release carrier for positively charged peptide drugs. The high stability, excellent loading efficiency, and sustained-release performance of M4R2 particles make them an ideal choice for the delivery of positively charged peptide drugs.

Conclusion

We developed three recombinant silk proteins, M4R2, M4R4, and M4R6, demonstrating that M4R2 particles, with stable colloidal properties, high loading efficiency of positively charged drugs, and controlled release rates, are promising new particulate drug carrier systems for the delivery of polypeptided drugs.

Chemical Conjugation of Iron Oxide Nanoparticles for the Development of Magnetically Directable Silk Particles

Magnetically directable materials containing iron oxide nanoparticles (IONPs) have been utilized for a variety of medical applications, including localized drug delivery. Regenerated silk fibroin (RSF) has also been used in numerous regenerative medicine and drug delivery applications, given its biocompatibility and tunable properties. In this work, we explored the hypothesis that chemically conjugating IONPs to RSF to anchor the IONPs to silk microparticles would provide better magnetic guidance than nonconjugated IONPs untethered to silk microparticles. IONPs were fabricated using a coprecipitation method and conjugated with glutathione (GSH) prior to mixing with RSF. IONPs incorporated into RSF were mixed with potassium phosphate buffer to fabricate microparticles. IONPs with and without GSH were characterized for particle size, shape, morphology, GSH conjugation efficiency, and composition. Silk iron microparticles (SIMPs) were also characterized for particle size, shape, and composition and tested for stability, degradation properties, magnetic movability, and cytotoxicity. IONPs demonstrated a uniform size distribution and spherical morphology. Conjugation of IONPs with GSH was verified through changes in the X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) spectra. IONPs and RSF were able to be chemically conjugated and fabricated into SIMPs, which demonstrated a spherical and porous morphology. FTIR revealed an increased β-sheet content in SIMPs, suggesting that the IONPs may be inducing conformational changes in the silk fibroin. SIMPs showed stability up to 4 weeks in ultrapure water and rapid enzymatic degradation within 24 h. SIMPs were able to be moved magnetically through solution and through a hydrogel and were not cytotoxic.

Fibroin-Hybrid Systems: Current Advances in Biomedical Applications

Fibroin, a protein extracted from silk, offers advantageous properties such as non-immunogenicity, biocompatibility, and ease of surface modification, which have been widely utilized for a variety of biomedical applications. However, in vivo studies have revealed critical challenges, including rapid enzymatic degradation and limited stability. To widen the scope of this natural biomacromolecule, the grafting of polymers onto the protein surface has been advanced as a platform to enhance protein stability and develop smart conjugates. This review article brings into focus applications of fibroin-hybrid systems prepared using chemical modification of the protein with polymers and inorganic compounds. A selection of recent preclinical evaluations of these hybrids is included to highlight the significance of this approach.

Natural Protein Films from Textile Waste for Wound Healing and Wound Dressing Applications

In recent years, several studies have focused on the development of sustainable, biocompatible, and biodegradable films with potential applications in wound healing and wound dressing systems. Natural macromolecules, particularly proteins, have emerged as attractive alternatives to synthetic polymers due to their biocompatibility, biodegradability, low immunogenicity, and adaptability. Among these proteins, keratin, extracted from waste wool, and fibroin, derived from Bombyx mori cocoons, exhibit exceptional properties such as mechanical strength, cell adhesion capabilities, and suitability for various fabrication methods. These proteins can also be functionalized with antimicrobial, antioxidant, and anti-inflammatory compounds, making them highly versatile for biomedical applications. This review highlights the promising potential of keratin- and fibroin-based films as innovative platforms for wound healing, emphasizing their advantages and the prospects they offer in creating next-generation wound dressing devices.

Cellular Interactions and Biological Effects of Silk Fibroin: Implications for Tissue Engineering and Regenerative Medicine

Silk fibroin (SF), the core structural protein derived from Bombyx mori silk, is extensively employed in tissue engineering and regenerative medicine due to its exceptional mechanical properties, favorable biocompatibility, tunable biodegradability, and versatile processing capabilities. Despite these advantages, current research predominantly focuses on SF biomaterials as structural scaffolds or drug carriers, often overlooking their potential role in modulating cellular behavior and tissue regeneration. This review aims to present a comprehensive overview of the inherent biological effects of SF biomaterials, independent of any exogenous biomolecules, and their implications for various tissue regeneration. It will cover in vitro cellular interactions of SF with various cell types, including stem cells and functional tissue cells such as osteoblasts, chondrocytes, keratinocytes, endothelial cells, fibroblasts, and epithelial cells. Moreover, it will summarize in vivo immune responses, cellular responses, and tissue regeneration following SF implantation, specifically focusing on vascular, bone, skin, cartilage, ocular, and tendon/ligament regeneration. Furthermore, it will address current limitations and future perspectives in the design of bioactive SF biomaterials. A comprehensive understanding of these cellular interactions and the biological effects of SF is crucial for predicting regenerative outcomes with precision and for designing SF-based biomaterials tailored to specific properties, enabling broader applications in regenerative medicine.

Recent advancements and perspectives on processable natural biopolymers: Cellulose, chitosan, eggshell membrane, and silk fibroin

With the rapid development of the global economy and the continuous consumption of fossil resources, sustainable and biodegradable natural biomass has garnered extensive attention as a promising substitute for synthetic polymers. Due to their hierarchical and nanoscale structures, natural biopolymers exhibit remarkable mechanical properties, along with excellent innate biocompatibility and biodegradability, demonstrating significant potential in various application scenarios. Among these biopolymers, proteins and polysaccharides are the most commonly studied due to their low cost, abundance, and ease of use. However, the direct processing/conversion of proteins and polysaccharides into their final products has been a long-standing challenge due to their natural morphology and compositions. In this review, we emphasize the importance of processing natural biopolymers into high-value-added products through sustainable and cost-effective methods. We begin with the extraction of four types of natural biopolymers: cellulose, chitosan, eggshell membrane, and silk fibroin. The processing and post-functionalization strategies for these natural biopolymers are then highlighted. Alongside their unique structures, the versatile potential applications of these processable natural biopolymers in biomedical engineering, biosensors, environmental engineering, and energy applications are illustrated. Finally, we provide a summary and future outlook on processable natural biopolymers, underscoring the significance of converting natural biopolymers into valuable biomaterial platforms.

Biological Functions of Macromolecular Protein Hydrogels in Constructing Osteogenic Microenvironment

Irreversible bone defects resulting from trauma, infection, and degenerative illnesses have emerged as a significant health concern. Structurally and functionally controllable hydrogels made by bone tissue engineering (BTE) have become promising biomaterials. Natural proteins are able to establish connections with autologous proteins through unique biologically active regions. Hydrogels based on proteins can simulate the bone microenvironment and regulate the biological behavior of stem cells in the tissue niche, making them candidates for research related to bone regeneration. This article reviews the biological functions of various natural macromolecular proteins (such as collagen, gelatin, fibrin, and silk fibroin) and highlights their special advantages as hydrogels. Then the latest research trends on cross-linking modified macromolecular protein hydrogels with improved mechanical properties and composite hydrogels loaded with exogenous micromolecular proteins have been discussed. Finally, the applications of protein hydrogels, such as 3D printed hydrogels, microspheres, and injectable hydrogels, were introduced, aiming to provide a reference for the repair of clinical bone defects.

Development and Application of an Advanced Biomedical Material-Silk Sericin

Sericin, a protein derived from silkworm cocoons, is considered a waste product derived from the silk industry for thousands of years due to a lack of understanding of its properties. However, in recent decades, a range of exciting properties of sericin are studied and uncovered, including cytocompatibility, low-immunogenicity, photo-luminescence, antioxidant properties, as well as cell-function regulating activities. These properties make sericin-based biomaterials promising candidates for biomedical applications. This review summarizes the properties and bioactivities of silk sericin and highlights the latest developments in sericin in tissue engineering and regenerative medicine. Furthermore, the extended application of sericin in developing flexible electronic devices and 3D bioprinting is also discussed. It is believed that sericin-based biomaterials have great potential of being developed into novel tissue engineering products and smart implantable devices for various medical applications toward improving clinical outcomes.

Development of pH-responsive Eudragit S100-functionalized silk fibroin nanoparticles as a prospective drug delivery system

Silk fibroin nanoparticles (FNP) have been increasingly investigated in biomedical fields due to their biocompatibility and biodegradability properties. To widen the FNP versatility and applications, and to control the drug release from the FNP, this study developed the Eudragit S100-functionalized FNP (ES100-FNP) as a pH-responsive drug delivery system, by two distinct methods of co-condensation and adsorption, employing the zwitterionic furosemide as a model drug. The particles were characterized by sizes and zeta potentials (DLS method), morphology (electron microscopy), drug entrapment efficiency and release profiles (UV-Vis spectroscopy), and chemical structures (FT-IR, XRD, and DSC). The ES100-FNP possessed nano-sizes of ∼200-350 nm, zeta potentials of ∼ -20 mV, silk-II structures, enhanced thermo-stability, non-cytotoxic to the erythrocytes, and drug entrapment efficiencies of 30%-60%, dependent on the formulation processes. Interestingly, the co-condensation method yielded the smooth spherical particles, whereas the adsorption method resulted in durian-shaped ones due to furosemide re-crystallization. The ES100-FNP adsorbed furosemide via physical adsorption, followed Langmuir model and pseudo-second-order kinetics. In the simulated oral condition, the particles could protect the drug in the stomach (pH 1.2), and gradually released the drug in the intestine (pH 6.8). Remarkably, in different pH conditions of 6.8, 9.5, and 12, the ES100-FNP could control the furosemide release rates depending on the formulation methods. The ES100-FNP made by the co-condensation method was mainly controlled by the swelling and corrosion process of ES100, and followed the Korsmeyer-Peppas non-Fickian transport mechanism. Whereas, the ES100-FNP made by the adsorption method showed constant release rates, followed the zero-order kinetics, due to the gradual furosemide dissolution in the media. Conclusively, the ES100-FNP demonstrated high versatility as a pH-responsive drug delivery system for biomedical applications.

Surface modification strategies for improved hemocompatibility of polymeric materials: a comprehensive review

Polymeric biomaterials are a widely used class of materials due to their versatile properties. However, as with all other types of materials used for biomaterials, polymers also have to interact with blood. When blood comes into contact with any foreign body, it initiates a cascade which leads to platelet activation and blood coagulation. The implant surface also has to encounter a thromboinflammatory response which makes the implant integrity vulnerable, this leads to blood coagulation on the implant and obstructs it from performing its function. Hence, the surface plays a pivotal role in the design and application of biomaterials. In particular, the surface properties of biomaterials are responsible for biocompatibility with biological systems and hemocompatibility. This review provides a report on recent advances in the field of surface modification approaches for improved hemocompatibility. We focus on the surface properties of polysaccharides, proteins, and synthetic polymers. The blood coagulation cascade has been discussed and blood - material surface interactions have also been explained. The interactions of blood proteins and cells with polymeric material surfaces have been discussed. Moreover, the benefits as well as drawbacks of blood coagulation on the implant surface for wound healing purposes have also been studied. Surface modifications implemented by other researchers to enhance as well as prevent blood coagulation have also been analyzed.

Piezoelectric dressings for advanced wound healing

The treatment of chronic refractory wounds poses significant challenges and threats to both human society and the economy. Existing research studies demonstrate that electrical stimulation fosters cell proliferation and migration and promotes the production of cytokines that expedites the wound healing process. Presently, clinical settings utilize electrical stimulation devices for wound treatment, but these devices often present issues such as limited portability and the necessity for frequent recharging. A cutting-edge wound dressing employing the piezoelectric effect could transform mechanical energy into electrical energy, thereby providing continuous electrical stimulation and accelerating wound healing, effectively addressing these concerns. This review primarily reviews the selection of piezoelectric materials and their application in wound dressing design, offering a succinct overview of these materials and their underlying mechanisms. This study also provides a perspective on the current limitations of piezoelectric wound dressings and the future development of multifunctional dressings harnessing the piezoelectric effect.

One-Pot Assembly of Drug-Eluting Silk Coatings with Applications for Nerve Regeneration

Clinical use of polymeric scaffolds for tissue engineering often suffers from their inability to promote strong cellular interactions. Functionalization with biomolecules may improve outcomes; however, current functionalization approaches using covalent chemistry or physical adsorption can lead to loss of biomolecule bioactivity. Here, we demonstrate a novel bottom-up approach for enhancing the bioactivity of poly(l-lactic acid) electrospun scaffolds though interfacial coassembly of protein payloads with silk fibroin into nanothin coatings. In our approach, protein payloads are first added into an aqueous solution with Bombyx mori-derived silk fibroin. Phosphate anions are then added to trigger coassembly of the payload and silk fibroin, as well as noncovalent formation of a payload-silk fibroin coating at poly(l-lactic) acid fiber surfaces. Importantly, the coassembly process results in homogeneous distribution of protein payloads, with the loading quantity depending on payload concentration in solution and coating time. This coassembly process yields greater loading capacity than physical adsorption methods, and the payloads can be released over time in physiologically relevant conditions. We also demonstrate that the coating coassembly process can incorporate nerve growth factor and that coassembled coatings lead to significantly more neurite extension than loading via adsorption in a rat dorsal root ganglia explant culture model.

Cross Talk Between Cells and the Current Bioceramics in Bone Regeneration: A Comprehensive Review

The conventional approach for addressing bone defects and stubborn non-unions typically involves the use of autogenous bone grafts. Nevertheless, obtaining these grafts can be challenging, and the procedure can lead to significant morbidity. Three primary treatment strategies for managing bone defects and non-unions prove resistant to conventional treatments: synthetic bone graft substitutes (BGS), a combination of BGS with bioactive molecules, and the use of BGS in conjunction with stem cells. In the realm of synthetic BGS, a multitude of biomaterials have emerged for creating scaffolds in bone tissue engineering (TE). These materials encompass biometals like titanium, iron, magnesium, and zinc, as well as bioceramics such as hydroxyapatite (HA) and tricalcium phosphate (TCP). Bone TE scaffolds serve as temporary implants, fostering tissue ingrowth and the regeneration of new bone. They are meticulously designed to enhance bone healing by optimizing geometric, mechanical, and biological properties. These scaffolds undergo continual remodeling facilitated by bone cells like osteoblasts and osteoclasts. Through various signaling pathways, stem cells and bone cells work together to regulate bone regeneration when a portion of bone is damaged or deformed. By targeting signaling pathways, bone TE can improve bone defects through effective therapies. This review provided insights into the interplay between cells and the current state of bioceramics in the context of bone regeneration.

Enhanced Osteogenic Potential of Noggin Knockout C2C12 Cells on BMP-2 Releasing Silk Scaffolds

The CRISPR/Cas9 mechanism offers promising therapeutic approaches for bone regeneration by stimulating or suppressing critical signaling pathways. In this study, we aimed to increase the activity of BMP-2 signaling through knockout of Noggin, thereby establishing a synergistic effect on the osteogenic activity of cells in the presence of BMP-2. Since Noggin is an antagonist expressed in skeletal tissues and binds to subunits of bone morphogenetic proteins (BMPs) to inhibit osteogenic differentiation, here Noggin expression was knocked out using the CRISPR/Cas9 system. In accordance with this purpose, C2C12 (mouse myoblast) cells were transfected with CRISPR/Cas9 plasmids. Transfection was achieved with Lipofectamine and confirmed with intense fluorescent signals in microscopic images and deletion in target sequence in Sanger sequencing analysis. Thus, Noggin knockout cells were identified as a new cell source for tissue engineering studies. Then, the transfected cells were seeded on highly porous silk scaffolds bearing BMP-2-loaded silk nanoparticles (30 ng BMP-2/mg silk nanoparticle) in the size of 288 ± 62 nm. BMP-2 is released from the scaffolds in a controlled manner for up to 60 days. The knockout of Noggin by CRISPR/Cas9 was found to synergistically promote osteogenic differentiation in the presence of BMP-2 through increased Coll1A1 and Ocn expression and mineralization. Gene editing of Noggin and BMP-2 increased almost 2-fold Col1A1 expression and almost 3-fold Ocn expression compared to the control group. Moreover, transfected cells produced extracellular matrix (ECM) containing collagen fibers on the scaffolds and mineral-like structures were formed on the fibers. In addition, mineralization characterized by intense Alizarin red staining was detected in transfected cells cultured in the presence of BMP-2, while the other groups did not exhibit any mineralized areas. As has been demonstrated in this study, the CRISPR/Cas9 mechanism has great potential for obtaining new cell sources to be used in tissue engineering studies.

The recombinant BMP-2 loaded silk fibroin microspheres improved the bone phenotype of mild osteogenesis imperfecta mice

Osteogenesis imperfecta (OI) is an inherited congenital disorder, characterized primarily by decreased bone mass and increased bone fragility. Bone morphogenetic protein-2 (BMP-2) is a potent cytokine capable of stimulating bone formation, however, its rapid degradation and unanticipated in vivo effects restrict its application. The sustained release characteristic of silk fibroin (SF) microspheres may potentially address the aforementioned challenges, nevertheless they have not previously been tested in OI treatment. In the current investigation, recombinant BMP-2 (rBMP-2) loaded SF (rBMP-2/SF) microspheres-based release carriers were prepared by physical adsorption. The SF microparticles were characterized by scanning electron microscopy (SEM) and were investigated for their cytotoxicity behavior as well as the release profile of rBMP-2. The rBMP-2/SF microspheres were administered via femoral intramedullary injection to two genotypes of OI-modeled mice daily for two weeks. The femoral microstructure and histological performance of OI mice were evaluated 2 weeks later. The findings suggested that rBMP-2/SF spheres with a rough surface and excellent cytocompatibility demonstrated an initial rapid release within the first three days (22.15 ± 2.88% of the loaded factor), followed by a transition to a slower and more consistent release rate, that persisted until the 15th day in an in vitro setting. The factor released from rBMP-2/SF particles exhibited favorable osteoinductive activity. Infusion of rBMP-2/SF microspheres, as opposed to blank SF spheres or rBMP-2 monotherapy, resulted in a noteworthy enhancement of femoral microstructure and promoted bone formation in OI-modeled mice. This research may offer a new therapeutic approach and insight into the management of OI. However, further investigation is required to determine the systematic safety and efficacy of rBMP-2/SF microspheres therapy for OI.

Engineered porosity for tissue-integrating, bioresorbable lifetime-based phosphorescent oxygen sensors

Versatile silk protein-based material formats were studied to demonstrate bioresorbable, implantable optical oxygen sensors that can integrate with the surrounding tissues. The ability to continuously monitor tissue oxygenation in vivo is desired for a range of medical applications. Silk was chosen as the matrix material due to its excellent biocompatibility, its unique chemistry that facilitates interactions with chromophores, and the potential to tune degradation time without altering chemical composition. A phosphorescent Pd (II) benzoporphyrin chromophore was incorporated to impart oxygen sensitivity. Organic solvent-based processing methods using 1,1,1,3,3,3-hexafluoro-2-propanol were used to fabricate: 1) silk-chromophore films with varied thickness and 2) silk-chromophore sponges with interconnected porosity. All compositions were biocompatible and exhibited photophysical properties with oxygen sensitivities (i.e., Stern-Volmer quenching rate constants of 2.7-3.2 × 104 M-1) useful for monitoring physiological tissue oxygen levels and for detecting deviations from normal behavior (e.g., hyperoxia). The potential to tune degradation time without significantly impacting photophysical properties was successfully demonstrated. Furthermore, the ability to consistently monitor tissue oxygenation in vivo was established via a multi-week rodent study. Histological assessments indicated successful tissue integration for the sponges, and this material format responded more quickly to various oxygen challenges than the film samples.

Factors Influencing Properties of Spider Silk Coatings and Their Interactions within a Biological Environment

Biomaterials are an indispensable part of biomedical research. However, although many materials display suitable application-specific properties, they provide only poor biocompatibility when implanted into a human/animal body leading to inflammation and rejection reactions. Coatings made of spider silk proteins are promising alternatives for various applications since they are biocompatible, non-toxic and anti-inflammatory. Nevertheless, the biological response toward a spider silk coating cannot be generalized. The properties of spider silk coatings are influenced by many factors, including silk source, solvent, the substrate to be coated, pre- and post-treatments and the processing technique. All these factors consequently affect the biological response of the environment and the putative application of the appropriate silk coating. Here, we summarize recently identified factors to be considered before spider silk processing as well as physicochemical characterization methods. Furthermore, we highlight important results of biological evaluations to emphasize the importance of adjustability and adaption to a specific application. Finally, we provide an experimental matrix of parameters to be considered for a specific application and a guided biological response as exemplarily tested with two different fibroblast cell lines.

State-of-the-art advances in nanocomposite and bio-nanocomposite polymeric materials: A comprehensive review

The modern eco-friendly materials used in research and innovation today consist of nanocomposites and bio-nanocomposite polymers. Their unique composite properties make them suitable for various industrial, medicinal, and energy applications. Bio-nanocomposite polymers are made of biopolymer matrices that have nanofillers dispersed throughout them. There are several types of fillers that can be added to polymers to enhance their quality, such as cellulose-based fillers, clay nanomaterials, carbon black, talc, carbon quantum dots, and many others. Biopolymer-based nanocomposites are considered a superior alternative to traditional materials as they reduce reliance on fossil fuels and promote the use of renewable resources. This review covers the current state-of-the-art in nanocomposite and bio-nanocomposite materials, focusing on ways to improve their features and the various applications they can be used for. The review article also investigates the utilization of diverse nanocomposites as a viable approach for developing bio-nanocomposites. It delves into the underlying principles that govern the synthesis of these materials and explores their prospective applications in the biomedical field, food packaging, sensing (Immunosensors), and energy storage devices. Lastly, the review discusses the future outlook and current challenges of these materials, with a focus on sustainability.

Application of Silk-Fibroin-Based Hydrogels in Tissue Engineering

Silk fibroin (SF) is an excellent protein-based biomaterial produced by the degumming and purification of silk from cocoons of the Bombyx mori through alkali or enzymatic treatments. SF exhibits excellent biological properties, such as mechanical properties, biocompatibility, biodegradability, bioabsorbability, low immunogenicity, and tunability, making it a versatile material widely applied in biological fields, particularly in tissue engineering. In tissue engineering, SF is often fabricated into hydrogel form, with the advantages of added materials. SF hydrogels have mostly been studied for their use in tissue regeneration by enhancing cell activity at the tissue defect site or counteracting tissue-damage-related factors. This review focuses on SF hydrogels, firstly summarizing the fabrication and properties of SF and SF hydrogels and then detailing the regenerative effects of SF hydrogels as scaffolds in cartilage, bone, skin, cornea, teeth, and eardrum in recent years.

Synthetic biology-guided design and biosynthesis of protein polymers for delivery

Vehicles derived from genetically engineered protein polymers have gained momentum in the field of biomedical engineering due to their unique designability, remarkable biocompatibility and excellent biodegradability. However, the design and production of these protein polymers with on-demand sequences and supramolecular architectures remain underexplored, particularly from a synthetic biology perspective. In this review, we summarize the state-of-the art strategies for constructing the highly repetitive genes encoding the protein polymers, and highlight the advanced approaches for metabolically engineering expression hosts towards high-level biosynthesis of the target protein polymers. Finally, we showcase the typical protein polymers utilized to fabricate delivery vehicles.

Synthesis and characterization of a novel, pH-responsive sustained release nanocarrier using polyethylene glycol, graphene oxide, and natural silk fibroin protein by a green nano emulsification method to enhance cancer treatment

In this study, for the first time, by employing a simple and efficient double nano-emulsification method and using sweet almond oil as the organic phase, polyethylene glycol (PEG)/graphene oxide (GO)/silk fibroin (SF) hydrogel-nanocomposite was synthesized. The aim of the research was to fabricate a biocompatible targeted pH-sensitive sustained release carrier, improve the drug loading capacity and enhance the anticancer effect of doxorubicin (DOX) drug. The obtained values for the entrapment (%EE) and loading efficacy (%LE) were 87.75 ± 0.7 % and 46 ± 1 %, respectively, and these high values were due to the use of GO with a large specific surface area and the electrostatic interaction between the drug and SF. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the presence of all the components in the nanocomposite and the suitable interaction between them. Based on the results of dynamic light scattering analysis (DLS) and zeta potential analysis, the mean size of the carrier particles and its surface charge were 293.7 nm and -102.9 mV, respectively. The high negative charge was caused by the presence of hydroxyl groups in GO and SF and it caused proper stability of the nanocomposite. The spherical core-shell structure with its homogeneous surface was also observed in the field emission scanning electron microscopy (FE-SEM) image. The cumulative release percentage of the nanocarrier reached 95.75 after 96 h and it is higher in the acidic environment at all times. The results of fitting the release data to the kinetic models suggested that the mechanism of release was dissolution-controlled anomalous at pH 7.4 and diffusion-controlled anomalous at pH 5.4. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry showed an increase in toxicity on MCF-7 cells and improved apoptotic cell death compared to the free drug. Consequently, the findings of this research introduced and confirmed PEG/GO/SF nanocomposite as an attractive novel drug delivery system for pH-sensitive and sustained delivery of chemotherapeutic agents in biomedicine.

Silk Fibroin Microneedles for Transdermal Drug Delivery: Where Do We Stand and How Far Can We Proceed?

Microneedles are a patient-friendly technique for delivering drugs to the site of action in place of traditional oral and injectable administration. Silk fibroin represents an interesting polymeric biomaterial because of its mechanical properties, thermal stability, biocompatibility and possibility of control via genetic engineering. This review focuses on the critical research progress of silk fibroin microneedles since their inception, analyzes in detail the structure and properties of silk fibroin, the types of silk fibroin microneedles, drug delivery applications and clinical trials, and summarizes the future development trend in this field. It also proposes the future research direction of silk fibroin microneedles, including increasing drug loading doses and enriching drug loading types as well as exploring silk fibroin microneedles with stimulation-responsive drug release functions. The safety and effectiveness of silk fibroin microneedles should be further verified in clinical trials at different stages.

Silk fibroin hydrogels for biomedical applications

Silk fibroin hydrogels occupy an essential position in the biomedical field due to their remarkable biological properties, excellent mechanical properties, flexible processing properties, as well as abundant sources and low cost. Herein, we introduce the unique structures and physicochemical characteristics of silk fibroin, including mechanical properties, biocompatibility, and biodegradability. Then, various preparation strategies of silk fibroin hydrogels are summarized, which can be divided into physical cross-linking and chemical cross-linking. Emphatically, the applications of silk fibroin hydrogel biomaterials in various biomedical fields, including tissue engineering, drug delivery, and wearable sensors, are systematically summarized. At last, the challenges and future prospects of silk fibroin hydrogels in biomedical applications are discussed.

Antibiotic-Loaded Hyperbranched Polyester Embedded into Peptide-Enriched Silk Fibroin for the Treatment of Orthopedic or Dental Infections

The development of innovative osteoconductive matrices, which are enriched with antibiotic delivery nanosystems, has the invaluable potential to achieve both local contaminant eradication and the osseointegration of implanted devices. With the aim of producing safe, bioactive materials that have osteoconductive and antibacterial properties, novel, antibiotic-loaded, functionalized nanoparticles (AFN)-based on carboxylic acid functionalized hyperbranched aliphatic polyester (CHAP) that can be integrated into peptide-enriched silk fibroin (PSF) matrices with osteoconductive properties-were successfully synthesized. The obtained AFNPSF sponges were first physico-chemically characterized and then tested in vitro against eukaryotic cells and bacteria involved in orthopedic or oral infections. The biocompatibility and microbiological tests confirmed the promising characteristics of the AFN-PSF products for both orthopedic and dental applications. These preliminary results encourage the establishment of AFN-PSF-based preventative strategies in the fight against implant-related infections.

Bioengineering of spider silks for the production of biomedical materials

Spider silks are well known for their extraordinary mechanical properties. This characteristic is a result of the interplay of composition, structure and self-assembly of spider silk proteins (spidroins). Advances in synthetic biology have enabled the design and production of spidroins with the aim of biomimicking the structure-property-function relationships of spider silks. Although in nature only fibers are formed from spidroins, in vitro, scientists can explore non-natural morphologies including nanofibrils, particles, capsules, hydrogels, films or foams. The versatility of spidroins, along with their biocompatible and biodegradable nature, also placed them as leading-edge biological macromolecules for improved drug delivery and various biomedical applications. Accordingly, in this review, we highlight the relationship between the molecular structure of spider silk and its mechanical properties and aims to provide a critical summary of recent progress in research employing recombinantly produced bioengineered spidroins for the production of innovative bio-derived structural materials.

Design of Hydrogel Silk-Based Microarrays and Molecular Beacons for Reagentless Point-of-Care Diagnostics

We have developed a novel microarray system based on three technologies: 1) molecular beacons designed to interact with DNA targets at room temperature (25-27°C), 2) tridimensional silk-based microarrays containing the molecular beacons immersed in the silk hydrogel, and 3) shallow angle illumination, which uses separated optical pathways for excitation and emission. Unlike conventional microarrays that exhibit reduced signal-to-background ratio, require several stages of incubation, rinsing, and stringency control, and measure only end-point results, our microarray technology provides enhanced signal-to-background ratio (achieved by separating the optical pathways for excitation and emission, resulting in reduced stray light), performs analysis rapidly in one step without the need for labeling DNA targets, and measures the entire course of association kinetics between target DNA and the molecular beacons. To illustrate the benefits of our technology, we conducted microarray assays designed for the identification of influenza viruses. We show that in a single microarray slide, we can identify the virus subtype according to the molecular beacons designed for hemagglutinin (H1, H2, and H3) and neuraminidase (N1, N2). We also show the identification of human and swine influenza using sequence-specific molecular beacons. This microarray technology can be easily implemented for reagentless point-of-care diagnostics of several contagious diseases, including coronavirus variants responsible for the current pandemic.

Harnessing the Structural and Functional Diversity of Protein Filaments as Biomaterial Scaffolds

The natural ability of many proteins to polymerize into highly structured filaments has been harnessed as scaffolds to align functional molecules in a diverse range of biomaterials. Protein-engineering methodologies also enable the structural and physical properties of filaments to be tailored for specific biomaterial applications through genetic engineering or filaments built from the ground up using advances in the computational prediction of protein folding and assembly. Using these approaches, protein filament-based biomaterials have been engineered to accelerate enzymatic catalysis, provide routes for the biomineralization of inorganic materials, facilitate energy production and transfer, and provide support for mammalian cells for tissue engineering. In this review, we describe how the unique structural and functional diversity in natural and computationally designed protein filaments can be harnessed in biomaterials. In addition, we detail applications of these protein assemblies as material scaffolds with a particular emphasis on applications that exploit unique properties of specific filaments. Through the diversity of protein filaments, the biomaterial engineer's toolbox contains many modular protein filaments that will likely be incorporated as the main structural component of future biomaterials.

Challenges in delivering therapeutic peptides and proteins: A silk-based solution

Peptide- and protein-based therapeutics have drawn significant attention over the past few decades for the treatment of infectious diseases, genetic disorders, oncology, and many other clinical needs. Yet, protecting peptide- and protein-based drugs from degradation and denaturation during processing, storage and delivery remain significant challenges. In this review, we introduce the properties of peptide- and protein-based drugs and the challenges associated with their stability and delivery. Then, we discuss delivery strategies using synthetic polymers and their advantages and limitations. This is followed by a focus on silk protein-based materials for peptide/protein drug processing, storage, and delivery, as a path to overcome stability and delivery challenges with current systems.

Bioactive Keratin and Fibroin Nanoparticles: An Overview of Their Preparation Strategies

In recent years, several studies have focused their attention on the preparation of biocompatible and biodegradable nanocarriers of potential interest in the biomedical field, ranging from drug delivery systems to imaging and diagnosis. In this regard, natural biomolecules—such as proteins—represent an attractive alternative to synthetic polymers or inorganic materials, thanks to their numerous advantages, such as biocompatibility, biodegradability, and low immunogenicity. Among the most interesting proteins, keratin extracted from wool and feathers, as well as fibroin extracted from Bombyx mori cocoons, possess all of the abovementioned features required for biomedical applications. In the present review, we therefore aim to give an overview of the most important and efficient methodologies for obtaining drug-loaded keratin and fibroin nanoparticles, and of their potential for biomedical applications.

The Effect of Sterilization on the Characteristics of Silk Fibroin Nanoparticles

In recent years, silk fibroin nanoparticles (SFNs) have been consolidated as drug delivery systems (DDSs) with multiple applications in personalized medicine. The design of a simple, inexpensive, and scalable preparation method is an objective pursued by many research groups. When the objective is to produce nanoparticles suitable for biomedical uses, their sterility is essential. To achieve sufficient control of all the crucial stages in the process and knowledge of their implications for the final characteristics of the nanoparticles, the present work focused on the final stage of sterilization. In this work, the sterilization of SFNs was studied by comparing the effect of different available treatments on the characteristics of the nanoparticles. Two different sterilization methods, gamma irradiation and autoclaving, were tested, and optimal conditions were identified to achieve the sterilization of SFNs by gamma irradiation. The minimum irradiation dose to achieve sterilization of the nanoparticle suspension without changes in the nanoparticle size, polydispersity, or Z-potential was determined to be 5 kiloGrays (kGy). These simple and safe methods were successfully implemented for the sterilization of SFNs in aqueous suspension and facilitate the application of these nanoparticles in medicine.

Enhanced osteogenic effect in reduced BMP-2 doses with siNoggin transfected pre-osteoblasts in 3D silk scaffolds

Bone morphogenetic proteins (BMPs), especially BMP-2, are being increasingly used in bone tissue engineering due to its osteo-inductive effects. Although recombinant human BMP-2 (rhBMP-2) was approved by Food and Drug Administration (FDA) to use for bone repair, its high doses cause undesired side effects. In order to reduce the BMP-2 dose for enhanced osteogenic differentiation, in this study we decided to suppress the synthesis of Noggin protein, the primary antagonist of BMP-2, on the MC3T3-E1 cells using Noggin targeted small interfering RNA (siRNA). Unlike other studies, Noggin siRNA (siNoggin) transfected cells were seeded on silk scaffolds, and osteogenic differentiation was investigated for a long-term period (21 days) with MTT, qPCR, SEM/EDS, and histological analysis. Besides, siNoggin transfected MC3T3-E1 cells were evaluated as a new cell source for tissue engineering studies. It was determined that Nog gene expression was suppressed in the siNoggin group and Ocn gene expression increased 5-fold compared to the control group (*p < 0.05). The osteogenic effect of BMP-2 was clearly observed in siNoggin transfected cells. According to the SEM/EDS analysis, the siNoggin group has mineral structures clustered on cells, which contain intense Ca and P elements. Histological staining showed that the siNoggin group has a more intense mineralized area than that of the control group. In conclusion, this study indicated that Noggin silencing by siRNA induces osteogenic differentiation in reduced BMP-2 doses for scaffold-based bone regeneration. This non-gene integration strategy has as a safe therapeutic potential to enhance tissue regeneration.

Applications of Phyto-Nanotechnology for the Treatment of Neurodegenerative Disorders

The strategies involved in the development of therapeutics for neurodegenerative disorders are very complex and challenging due to the existence of the blood-brain barrier (BBB), a closely spaced network of blood vessels and endothelial cells that functions to prevent the entry of unwanted substances in the brain. The emergence and advancement of nanotechnology shows favourable prospects to overcome this phenomenon. Engineered nanoparticles conjugated with drug moieties and imaging agents that have dimensions between 1 and 100 nm could potentially be used to ensure enhanced efficacy, cellular uptake, specific transport, and delivery of specific molecules to the brain, owing to their modified physico-chemical features. The conjugates of nanoparticles and medicinal plants, or their components known as nano phytomedicine, have been gaining significance lately in the development of novel neuro-therapeutics owing to their natural abundance, promising targeted delivery to the brain, and lesser potential to show adverse effects. In the present review, the promising application, and recent trends of combined nanotechnology and phytomedicine for the treatment of neurological disorders (ND) as compared to conventional therapies, have been addressed. Nanotechnology-based efforts performed in bioinformatics for early diagnosis as well as futuristic precision medicine in ND have also been discussed in the context of computational approach.

Protein-Based Systems for Topical Antibacterial Therapy

Recently, proteins are gaining attention as potential materials for antibacterial therapy. Proteins possess beneficial properties such as biocompatibility, biodegradability, low immunogenic response, ability to control drug release, and can act as protein-mimics in wound healing. Different plant- and animal-derived proteins can be developed into formulations (films, hydrogels, scaffolds, mats) for topical antibacterial therapy. The application areas for topical antibacterial therapy can be wide including bacterial infections in the skin (e.g., acne, wounds), eyelids, mouth, lips, etc. One of the major challenges of the healthcare system is chronic wound infections. Conventional treatment strategies for topical antibacterial therapy of infected wounds are inadequate, and the development of newer and optimized formulations is warranted. Therefore, this review focuses on recent advances in protein-based systems for topical antibacterial therapy in infected wounds. The opportunities and challenges of such protein-based systems along with their future prospects are discussed.

A review on advances in the applications of spider silk in biomedical issues

Spider silk, as one of the hardest natural and biocompatible substances with extraordinary strength and flexibility, have become an ideal option in various areas of science and have made their path onto the biomedical industry. Despite its growing popularity, the difficulties in the extraction of silks from spiders and farming them have made it unaffordable and almost impossible for industrial scale. Biotechnology helped production of spider silks recombinantly in different hosts and obtaining diverse morphologies out of them based on different processing and assembly procedures. Herein, the characteristics of these morphologies and their advantages and disadvantages are summarized. A detailed view about applications of recombinant silks in skin regeneration and cartilage, tendon, bone, teeth, cardiovascular, and neural tissues engineering are brought out, where there is a need for strong scaffolds to support cell growth. Likewise, spider silk proteins have applications as conduit constructs, medical sutures, and 3D printer bioinks. Other characteristics of spider silks, such as low immunogenicity, hydrophobicity, homogeneity, and adjustability, have attracted much attention in drug and gene delivery. Finally, the challenges and obstacles ahead for industrializing the production of spider silk proteins in sufficient quantities in biomedicine, along with solutions to overcome these barriers, are discussed.

Biomedical applications of silkworm (Bombyx Mori) proteins in regenerative medicine (a narrative review)

Silk worm (Bombyx Mori) protein, have been considered as potential materials for a variety of advanced engineering and biomedical applications for decades. Recently, silkworm silk has gained significant importance in research attention mainly because of its remarkable and exceptional mechanical properties. Silk has already been shown to have unique interactions with cells in tissues through bio-recognition units. The natural silk contains fibroin and sericin and has been used in various tissues of the human body (skin, bone, nerve, and so on). Besides, silk also still has anti-cancer, anti-tyrosinase, anti-coagulant, anti-oxidant, anti-bacterial, and anti-diabetic properties. This article is supposed to describe the diverse biomedical capabilities of B. Mori silk as the appropriate biomaterial among the assorted natural and artificial polymers that are presently accessible, and ideal for usage in regenerative medicine fields.

Computational analysis of vincristine loaded silk fibroin hydrogel for sustained drug delivery applications: Multiphysics modeling and experiments

In this paper, silk fibroin hydrogel is used as a drug carrier for vincristine. To optimize drug delivery, a multi-physics model is proposed that couples the deformation and diffusion fields. We applied inverse analysis and general continuum mechanics to define material parameters and mechanical properties. To examine the mass transport and chemical behavior, an affinity-based diffusion and degradation of a drug-loaded polymer matrix is employed. Some experiments are carried out to examine the capability of the presented model. After preparing the vincristine loaded silk hydrogel syringes, they were injected into PBS and enzyme solutions to monitor the drug release rate for 40 days. Obtained results from the computational simulation and laboratory tests showed that the silk fibroin hydrogel was deswelled after about 40 days in enzyme solution. Degradation led to faster and higher doses of vincristine drug release in comparison to the case of PBS solution. Results revealed that more than 80% of the drug was released in the first 5 days in the enzyme solution, but in PBS solution only 10% of the drug was released during 40 days. The model predictions of deswelling behavior and drug release rate were in good agreement with those of experimental results. Therefore, it can be employed as a reliable tool for further predictions.

Quantitative proteomic analysis uncovers inhibition of melanin synthesis by silk fibroin via MITF/tyrosinase axis in B16 melanoma cells

AIMS

Silk fibroin (SF), a natural product from silkworms, has been used to promote anti-inflammation, induce wound healing, and reduce melanin production. However, the underlying regulatory mechanism of SF on melanin production remains unknown. The aim of this study was to investigate the distinct regulatory mechanism of SF in B16 melanoma cells by applying quantitative proteomic approach.

MATERIALS AND METHODS

B16 melanoma cells were treated with PBS, KA or SF for 48 h, respectively. Cell viability, melanin content, and tyrosinase activity were examined. A label-free quantitative proteomic approach was utilized to investigate the regulatory mechanism of SF. The differentially expressed proteins and their related biological processes were subsequently identified by bioinformatics methods. Furthermore, the identified differentially expressed proteins were validated by western blot.

KEY FINDINGS

Both SF and KA were able to suppress the melanin synthesis of B16 melanoma cells without appreciable toxicity; yet, SF had a distinct effect on mushroom tyrosinase activity in vitro. Moreover, quantitative proteomic approach identified 141 proteins differentially expressed only in SF/Con group. Bioinformatic analysis of these proteins revealed that oxidation-reduction process, RNA processing, fatty acid degradation, as well as melanin biosynthetic process were enriched with SF treatment. The proteins associated with melanin biosynthetic process, including microphthalmia-associated transcription factor (MITF) and tyrosinase, were down-regulated in SF group, which was confirmed by western blot.

SIGNIFICANCE

SF inhibited melanin synthesis in B16 melanoma cells via down-regulation of MITF and tyrosinase expression, which provides a rationale for future utilization of SF.

Systemic and Local Silk-Based Drug Delivery Systems for Cancer Therapy

For years, surgery, radiotherapy, and chemotherapy have been the gold standards to treat cancer, although continuing research has sought a more effective approach. While advances can be seen in the development of anticancer drugs, the tools that can improve their delivery remain a challenge. As anticancer drugs can affect the entire body, the control of their distribution is desirable to prevent systemic toxicity. The application of a suitable drug delivery platform may resolve this problem. Among other materials, silks offer many advantageous properties, including biodegradability, biocompatibility, and the possibility of obtaining a variety of morphological structures. These characteristics allow the exploration of silk for biomedical applications and as a platform for drug delivery. We have reviewed silk structures that can be used for local and systemic drug delivery for use in cancer therapy. After a short description of the most studied silks, we discuss the advantages of using silk for drug delivery. The tables summarize the descriptions of silk structures for the local and systemic transport of anticancer drugs. The most popular techniques for silk particle preparation are presented. Further prospects for using silk as a drug carrier are considered. The application of various silk biomaterials can improve cancer treatment by the controllable delivery of chemotherapeutics, immunotherapeutics, photosensitizers, hormones, nucleotherapeutics, targeted therapeutics (e.g., kinase inhibitors), and inorganic nanoparticles, among others.

The rough inhalable ciprofloxacin hydrochloride microparticles based on silk fibroin for non-cystic fibrosis bronchiectasis therapy with good biocompatibility

Non-cystic fibrosis bronchiectasis (NCFB) is a chronic respiratory disease, and the thick and viscous mucus covering on respiratory epithelia can entrap the inhaled drugs, resulting in compromised therapeutic efficiency. In order to solve this problem, the inhalable ciprofloxacin hydrochloride microparticles (CMs) based on silk fibroin (SF) and mannitol (MAN) were designed and developed. SF was applied to increase the loading efficiency of ciprofloxacin hydrochloride by strong electrostatic interactions. MAN could facilitate the penetration of drugs through mucus, which ensured the drugs could reach their targets before clearance. Furthermore, the aerodynamic performance of the inhalable microparticles could be tuned by changing the surface roughness to achieve a high fine particle fraction value (45.04%). The antibacterial effects of CMs were also confirmed by measuring the minimum inhibitory concentration against four different bacteria strains. Moreover, a series of experiments both in vitro and in vivo showed that CMs would not affect the lung function and induce the secretion of inflammatory cytokines in lungs, demonstrating their excellent biocompatibility and biosafety. Therefore, CMs might be a promising pulmonary drug delivery system for the treatment of NCFB.

Molecularly Imprinted Silk Fibroin Nanoparticles

Nanosized biomimetics prepared by the strategy of molecular imprinting, that is, the stamping of recognition sites by means of a template-assisted synthesis, are demonstrating potential as plastic antibodies in medicine, proving effective for cell imaging and targeted therapies. Most molecularly imprinted nanoparticles (MIP-NPs) are currently made of soft matter, such as polyacrylamide and derivatives. Yet, MIP-NPs biocompatibility is crucial for their effective translation into clinical uses. Here, we propose the original idea to synthesize fully biocompatible molecularly imprinted nanoparticles starting from the natural polymer silk fibroin (MIP SF-NPs), which is nontoxic and highly biocompatible. The conditions to produce MIP SF-NPs of different sizes (d_mean ∼ 50 nm; d_mean ∼ 100 nm) were set using the response surface method. The stamping of a single, high affinity (K_D = 57 × 10^-9 M), and selective recognition site per silk fibroin nanoparticle was demonstrated, together with the confirmation of nontoxicity. Additionally, MIP SF-NPs were used to decorate silk microfibers and silk nanofibers, providing a general means to add entailed biofunctionalities to materials.

Self-assembling peptides as vectors for local drug delivery and tissue engineering applications

Molecular self-assembly has forged a new era in the development of advanced biomaterials for local drug delivery and tissue engineering applications. Given their innate biocompatibility and biodegradability, self-assembling peptides (SAPs) have come in the spotlight of such applications. Short and water-soluble SAP biomaterials associated with enhanced pharmacokinetic (PK) and pharmacodynamic (PD) responses after the topical administration of the therapeutic systems, or improved regenerative potential in tissue engineering applications will be the focus of the current review. SAPs are capable of generating supramolecular structures using a boundless array of building blocks, while peptide engineering is an approach commonly pursued to encompass the desired traits to the end composite biomaterials. These two elements combined, expand the spectrum of SAPs multi-functionality, constituting them potent biomaterials for use in various biomedical applications.

In Vitro Interaction of Doxorubicin-Loaded Silk Sericin Nanocarriers with MCF-7 Breast Cancer Cells Leads to DNA Damage

In this paper, Bombyx mori silk sericin nanocarriers with a very low size range were obtained by nanoprecipitation. Sericin nanoparticles were loaded with doxorubicin, and they were considered a promising tool for breast cancer therapy. The chemistry, structure, morphology, and size distribution of nanocarriers were investigated by Fourier transformed infrared spectroscopy (FTIR–ATR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and dynamic light scattering (DLS). Morphological investigation and DLS showed the formation of sericin nanoparticles in the 25–40 nm range. FTIR chemical characterization showed specific interactions of protein–doxorubicin–enzymes with a high influence on the drug delivery process and release behavior. The biological investigation via breast cancer cell line revealed a high activity of nanocarriers in cancer cells by inducing significant DNA damage.

An overview of latest advances in exploring bioactive peptide hydrogels for neural tissue engineering

Neural tissue engineering holds great potential in addressing current challenges faced by medical therapies employed for the functional recovery of the brain. In this context, self-assembling peptides have gained considerable interest owing to their diverse physicochemical properties, which enable them to closely mimic the biophysical characteristics of the native ECM. Additionally, in contrast to synthetic polymers, which lack inherent biological signaling, peptide-based nanomaterials could be easily designed to present essential biological cues to the cells to promote cellular adhesion. Moreover, injectability of these biomaterials further widens their scope in biomedicine. In this context, hydrogels obtained from short bioactive peptide sequences are of particular interest owing to their facile synthesis and highly tunable properties. In spite of their well-known advantages, the exploration of short peptides for neural tissue engineering is still in its infancy and thus detailed discussion is required to evoke interest in this direction. This review provides a general overview of various bioactive hydrogels derived from short peptide sequences explored for neural tissue engineering. The review also discusses the current challenges in translating the benefits of these hydrogels to clinical practices and presents future perspectives regarding the utilization of these hydrogels for advanced biomedical applications.