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Materials Science in Additive Manufacturing Fibrous silk in biomedicine

cell behavior, highlighting their potential for extensive Similarly, Mobini et al. incorporated FS into a
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applications in vascular tissue regeneration. regenerated SF matrix and produced composite scaffolds
In summary, natural FS-based composite vascular through freeze-drying. Evaluations through electron
grafts possess immense potential due to their superior microscopy, mechanical testing, and in vitro cell assays were
biocompatibility and mechanical properties. These conducted to assess the properties of these composites.
advancements offer promising solutions for the fabrication Scanning electron microscopy revealed an interconnected
of small-diameter artificial blood vessels and address porous structure that fostered cell adhesion and growth.
challenges such as graft scarcity and donor site morbidity. Mechanical experiments revealed that FS addition
increased the compression modulus and compressive stress.
4.5. Bone tissue regeneration Furthermore, human MSCs cultured on the composite
Bone is a specialized connective tissue composed of a scaffolds exhibited enhanced adhesion, proliferation, and
calcified matrix, consisting of approximately 70% inorganic osteogenic differentiation, positioning the material as a
material (primarily hydroxyapatite) and 30% organic promising candidate for bone tissue engineering research.
material (mainly collagen I). It provides structural Moreover, undegummed raw FS has shown research
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support for the body extremities and protection for internal value in the development of apatite-organic polymer
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organs. Bone defects, resulting from trauma, infections, hybrids. Takeuchi et al. explored apatite deposition
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tumors, and other conditions, present significant clinical on organic surfaces, including raw and degummed FS,
challenges by impairing physiological functions. Timely under physiological conditions. Their results indicated
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and effective repair of bone defects is therefore crucial. that the sericin present in raw FS promoted greater apatite
deposition compared to degummed FS, suggesting its
Autologous bone grafting remains the gold standard for potential for developing bone-mimicking polymers with
bone repair; however, its clinical application is limited by improved bonding and mechanical properties through
graft availability and infection risk. Although allogeneic biomimetic approaches.
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bone is more readily available, it is associated with
antigenic issues, high costs, immune rejection, and safety 4.6. Antimicrobial activity
concerns. Artificial bone substitutes have thus emerged FS exhibits high plasticity, exceptional breathability,
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as alternatives, aiming to restore normal anatomical and safety, non-toxicity, and wound-healing properties,
physiological functions. 155 making it suitable for use in skin wound dressings. Prior
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Bone tissue engineering seeks to develop materials that research has confirmed FS’s antimicrobial properties,
meet several key requirements: (i) mechanical properties demonstrating its ability to inhibit microbial growth.
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comparable to human bone, (ii) adaptability to diverse Academic studies have further highlighted FS’s notable
bone shapes, (iii) osteoinductivity to stimulate stem cell antifungal properties. Key bioactive components – such
differentiation, (iv) osteoconductivity to support new as Kunitz-type BmSPI 51, TIL-type BmSPI 38, BmSPI
bone growth, and (v) seamless integration with existing 39, and phosphatidylethanolamine-binding protein –
bone tissue. Although many materials partially fulfill these have been shown to significantly inhibit fungal spore
criteria, silk fibers, with their unique biocompatibility, growth in vitro. 160-165 In addition, FS demonstrates
mechanical strength, and structural plasticity, are broad-spectrum antimicrobial efficacy against bacteria,
increasingly recognized as promising candidates for bone viruses, and other pathogens. FS contains two serotonin
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tissue engineering. Future work is expected to further derivatives (serotonin 1 and serotonin 2) that hinder
unlock the potential of silk-based materials in this field. pathogen growth, thereby broadening its antimicrobial
spectrum. 31,166-169 Enzymes such as phenol oxidase and
Compared to SF, the application of FS in bone repair
remains underutilized. Researchers often convert FS into peroxidase contribute to pathogen elimination through
the generation of reactive by-products. In addition,
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a solution for scaffold printing. Studies have revealed that non-organic acids, alkaloids, and flavonoids present in
incorporating FS into CPC boosts mechanical strength by FS contribute to its robust antimicrobial activity. 166,171,172
leveraging the principle of fiber reinforcement. Zhou et al. Crude sericin extracted from FS, especially from the outer
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explored the application of SF in bone repair by mixing cocoon layer, has demonstrated potent antibacterial effects
FS and CPC at a 1:20 ratio to fabricate bio-composite against Escherichia coli and Staphylococcus aureus. 173
cylinders (4 mm in diameter and 15 mm in length) for
animal testing. The results indicated that FS significantly Furthermore, FS serves as a versatile platform
enhanced the mechanical and biological properties of the for antimicrobial material design, enabling tailored
composite, promoted osteogenesis, and effectively repaired functionalization. Researchers have enhanced FS’s
bone defects. antimicrobial capacity through various chemical and

Volume 4 Issue 2 (2025) 12 doi: 10.36922/MSAM025130020