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Materials Science in Additive Manufacturing Fibrous silk in biomedicine

for producing recombinant proteins, peptides, genes, and bodies. Delayed allergic reactions to FS sutures have been
other bioproducts. This facilitates large-scale transgenic attributed to sericin, which elevates IgE levels and induces
production and enhances FS’s mechanical properties. hypersensitivity reactions. Degumming, which removes
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Genetic modifications not only introduce novel functions sericin from FS, significantly enhances its biosafety by
but also enhance material strength. For instance, Japanese promoting cell adhesion and differentiation. Studies
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researchers by Teramoto et al. developed transgenic by Meinel et al. and Boni et al. have confirmed that
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silkworms with an expanded genetic code capable of degummed FS becomes immunologically inert and does not
incorporating azido groups into SF, thereby enabling the trigger an immune response. Consequently, degumming –
large-scale production of functionalized silk fibers. This often performed through protease digestion – is a critical step
approach provides a promising strategy for developing to improve FS biocompatibility and expand its applications
high-performance silk materials through click chemistry- beyond those of raw FS. Complete sericin removal from FS is
based modifications. crucial for producing clinically suitable FS biomaterials.
3.2. Biosafety and immune interaction Multiple studies have affirmed the superior biosafety
of silk proteins compared to synthetic polymers. The
FS demonstrates superior biocompatibility, immunogenicity and antigenicity of FS scaffolds have been
biodegradability, and non-toxic, non-irritating properties thoroughly evaluated, with silk-fibronectin conjugates
compared to synthetic polymer compounds, such as demonstrating favorable outcomes in musculoskeletal
polyetheretherketone and polylactic acid, which are treatments. For example, a study by Zhou et al. using a
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widely employed in clinical applications. Additional rabbit model showed no infection despite some immune
investigations have demonstrated that properly degummed cell accumulation, although sericin’s adverse effects on
and sterilized FS exhibits biocompatibility comparable to immune responses remain inconclusive. Further research
other widely used biomaterials, including polylactic acid is needed to comprehensively verify FS biosafety and
and collagen. Table 2 shows that FS supports human immune interactions for biomaterial applications.
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fibroblast proliferation, exhibits low hemolytic activity, Due to its excellent biocompatibility, modified FS
and elicits only a mild foreign body response, indicating sutures have been widely used in tissue engineering for
excellent biocompatibility relative to other fiber materials.
bone, tendon, and ligament repair. Kardestuncer et al.
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Historically, FS has been widely used as a suture material cultured human tendon cells on Arg-Gly-Asp (RGD)-
for centuries due to its proven biosafety profile. However, modified FS sutures. The modified sutures exhibited
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the combination of SF and sericin can trigger inflammatory enhanced tendon cell adhesion, proliferation, and
responses, a natural defense mechanism against foreign differentiation compared to both unmodified FS sutures

Table 2. Biocompatibility and biodegradability of silk and other common fibrous materials
Materials Supported tissues or Key findings Foreign body Biodegradation time References
cell type response a

Silkworm silk fiber Human fibroblasts Supports cell proliferation with low Mild Slow(>12weeks) 85

(without sericin) hemolysis
Spider silk Subcutaneous tissue No impairment in wound healing; no Mild Slow(>12weeks) 85

in rats infection or ectopic inflammation
Kevlar Paravertebral muscles Slight fibrotic tissue reaction; foreign Severe Non-biodegradable 184
in rabbits body giant cells observed near fibers
Nylon Rat tendon cells Comparable to Kevlar in cellular Moderate Slow(several years) 185,186

response and growth rate
Collagen Bovine tendon Facilitates tendon fibroblast migration, Mild Moderate(4–12weeks) 187

fibroblasts attachment, and proliferation

Polylactic acid Bone mesenchymal High cell viability and cytocompatibility Mild to moderate Fast(2–12weeks) 85

stem cell for bone repair
Notes: Classification of foreign body response:
a
• Mild: Characterized by slight inflammation and minimal infiltration of monocytes and macrophages, with no significant tissue damage or fibrosis.
• Moderate: Characterized by moderate inflammation, increased infiltration of monocytes, macrophages, and some neutrophils, potentially resulting in
minor fibrosis and localized tissue damage.
• Severe: Characterized by extensive inflammation, pronounced infiltration of macrophages and neutrophils, marked tissue fibrosis, and necrosis,
potentially leading to severe tissue damage.
Volume 4 Issue 2 (2025) 6 doi: 10.36922/MSAM025130020