Native Spider Silk-Based Antimicrobial Hydrogels for Biomedical Applications

In vitro and in vivo investigation of Argiope bruennichi spider silk-based novel biomaterial for medical use

As a natural and biocompatible material with high strength and flexibility, spider silk is frequently used in biomedical studies. In this study, the availability of Argiope bruennichi spider silk as a surgical suture material was investigated. The effects of spider silk-based and commercial sutures, with and without Aloe vera coating, on wound healing were evaluated by a rat dorsal skin flap model, postoperatively (7th and 14th days). Biochemical, hematological, histological, immunohistochemical, small angle x-ray scattering (SAXS) analyses and mechanical tests were performed. A. bruennichi silk did not show any cytotoxic effect on the L929 cell line according to MTT and LDH assays, in vitro. The silk materials did not cause any allergic reaction, infection, or systemic effect in rats according to hematological and biochemical analyses. A. bruennichi spider silk group showed a similar healing response to commercial sutures. SAXS analysis showed that the 14th-day applications of A. bruennichi spider silk and A. vera coated commercial suture groups have comparable structural results with control group. In conclusion, A. bruennichi spider silk is biocompatible in line with the parameters examined and shows a healing response similar to the commercial sutures commonly used in the skin.

Review of Spider Silk Applications in Biomedical and Tissue Engineering

This review will present the latest research related to the production and application of spider silk and silk-based materials in reconstructive and regenerative medicine and tissue engineering, with a focus on musculoskeletal tissues, and including skin regeneration and tissue repair of bone and cartilage, ligaments, muscle tissue, peripheral nerves, and artificial blood vessels. Natural spider silk synthesis is reviewed, and the further recombinant production of spider silk proteins. Research insights into possible spider silk structures, like fibers (1D), coatings (2D), and 3D constructs, including porous structures, hydrogels, and organ-on-chip designs, have been reviewed considering a design of bioactive materials for smart medical implants and drug delivery systems. Silk is one of the toughest natural materials, with high strain at failure and mechanical strength. Novel biomaterials with silk fibroin can mimic the tissue structure and promote regeneration and new tissue growth. Silk proteins are important in designing tissue-on-chip or organ-on-chip technologies and micro devices for the precise engineering of artificial tissues and organs, disease modeling, and the further selection of adequate medical treatments. Recent research indicates that silk (films, hydrogels, capsules, or liposomes coated with silk proteins) has the potential to provide controlled drug release at the target destination. However, even with clear advantages, there are still challenges that need further research, including clinical trials.

Microstructure of the silk fibroin-based hydrogel scaffolds derived from the orb-web spider Trichonephila clavata

Due to the unique properties of the silk fibroin (SF) made from silkworm, SF-based hydrogels have recently received significant attention for various biomedical applications. However, research on the SF-based hydrogels isolated from spider silks has been rtricted due to the limited collection and preparation of naïve silk materials. Therefore, this study focused on the microstructural characteristics of hydrogel scaffolds derived from two types of woven silk glands: the major ampullate gland (MAG) and the tubuliform gland (TG), in the orb-web spider Trichonephila clavate. We compared these spider glands with those of the silk fibroin (SF) hydrogel scaffold extracted from the cocoon of the insect silkworm Bombyx mori. Our FESEM analysis revealed that the SF hydrogel has high porosity, translucency, and a loose upper structure, with attached SF fibers providing stability. The MAG hydrogel displayed even higher porosity, as well as elongated fibrous structures, and improved mechanical properties: while the TG hydrogel showed increased porosity, ridge-like or wall-like structures, and stable biocapacity formed by physical crosslinking. Due to their powerful and versatile microstructural characteristics, the MAG and TG hydrogels can become tailored substrates, very effective for tissue engineering and regenerative medicine applications.

3D Printed Materials for Combating Antimicrobial Resistance

Three-dimensional (3D) printing is a rapidly growing technology with a significant capacity for translational applications in both biology and medicine. 3D-printed living and non-living materials are being widely tested as a potential replacement for conventional solutions for testing and combating antimicrobial resistance (AMR). The precise control of cells and their microenvironment, while simulating the complexity and dynamics of an in vivo environment, provides an excellent opportunity to advance the modeling and treatment of challenging infections and other health conditions. 3D-printing models the complicated niches of microbes and host-pathogen interactions, and most importantly, how microbes develop resistance to antibiotics. In addition, 3D-printed materials can be applied to testing and delivering antibiotics. Here, we provide an overview of 3D printed materials and biosystems and their biomedical applications, focusing on ever increasing AMR. Recent applications of 3D printing to alleviate the impact of AMR, including developed bioprinted systems, targeted bacterial infections, and tested antibiotics are presented.

Biomedical applications of silk and its role for intervertebral disc repair

Intervertebral disc (IVD) degeneration (IDD) is the main contributor to chronic low back pain. To date, the present therapies mainly focus on treating the symptoms caused by IDD rather than addressing the problem itself. For this reason, researchers have searched for a suitable biomaterial to repair and/or regenerate the IVD. A promising candidate to fill this gap is silk, which has already been used as a biomaterial for many years. Therefore, this review aims first to elaborate on the different origins from which silk is harvested, the individual composition, and the characteristics of each silk type. Another goal is to enlighten why silk is so suitable as a biomaterial, discuss its functionalization, and how it could be used for tissue engineering purposes. The second part of this review aims to provide an overview of preclinical studies using silk-based biomaterials to repair the inner region of the IVD, the nucleus pulposus (NP), and the IVD's outer area, the annulus fibrosus (AF). Since the NP and the AF differ fundamentally in their structure, different therapeutic approaches are required. Consequently, silk-containing hydrogels have been used mainly to repair the NP, and silk-based scaffolds have been used for the AF. Although most preclinical studies have shown promising results in IVD-related repair and regeneration, their clinical transition is yet to come.

Progress in Antibacterial Hydrogel Dressing

Antibacterial hydrogel has excellent antibacterial property and good biocompatibility, water absorption and water retention, swelling, high oxygen permeability, etc.; therefore, it widely applied in biomedicine, intelligent textiles, cosmetics, and other fields, especially for medical dressing. As a wound dressing, the antibacterial hydrogel has the characteristics of absorbing wound liquid, controlling drug release, being non-toxic, being without side effects, and not causing secondary injury to the wound. Its preparation method is simple, and can crosslink via covalent or non-covalent bond, such as γ-radiation croFsslinking, free radical polymerization, graft copolymerization, etc. The raw materials are easy to obtain; usually these include chondroitin sulfate, sodium alginate, polyvinyl alcohol, etc., with different raw materials being used for different antibacterial modes. According to the hydrogel matrix and antibacterial mode, the preparation method, performance, antibacterial mechanism, and classification of antibacterial hydrogels are summarized in this paper, and the future development direction of the antibacterial hydrogel as wound dressing is proposed.

Spider Silk-Improved Quartz-Enhanced Conductance Spectroscopy for Medical Mask Humidity Sensing

Spider silk is one of the hottest biomaterials researched currently, due to its excellent mechanical properties. This work reports a novel humidity sensing platform based on a spider silk-modified quartz tuning fork (SSM-QTF). Since spider silk is a kind of natural moisture-sensitive material, it does not demand additional sensitization. Quartz-enhanced conductance spectroscopy (QECS) was combined with the SSM-QTF to access humidity sensing sensitively. The results indicate that the resonance frequency of the SSM-QTF decreased monotonously with the ambient humidity. The detection sensitivity of the proposed SSM-QTF sensor was 12.7 ppm at 1 min. The SSM-QTF sensor showed good linearity of ~0.99. Using this sensor, we successfully measured the humidity of disposable medical masks for different periods of wearing time. The results showed that even a 20 min wearing time can lead to a >70% humidity in the mask enclosed space. It is suggested that a disposable medical mask should be changed <2 h.