Table 2. Comparison of chitosan nanofibers (ChNFs), nanocellulose (NCs), and silk fibroin.

Type	Properties	ChNFs	Nanocellulose	Silk fibroin	Ref.
Structural properties	Size	2–5 nm	10–90 nm	150–400 nm	5, 100 and 101
	Surface area to volume ratio	High surface area due to the nanoscale size and fibrillar structure	Slightly higher due to narrower fibers	Lower than cellulose or chitin due to larger aggregates	102 and 103
	Crystal structure	α-Chitin crystal structure with antiparallel arrangement	Cellulose Iβ structure in native cellulose	β-sheet crystalline regions in its native form	104–106
Mechanical properties	Tensile strength	Partially deacetylated ChNF films exhibit the highest tensile strength of ∼140 MPa	Cellulose nanofiber green composites can achieve tensile strengths up to 90 MPa, comparable to glass-fiber-reinforced plastics	Ultrathin silk fibroin films have high tensile strength and toughness due to their self-reinforcing microstructure	107, 108 and 109
	Young's modulus	Chitin nanopapers from mushroom extract have a Young's modulus of around 7 GPa	The Young's modulus of cellulose nanofibers from different sources ranges from 102 to 131 GPa, as measured by atomic force microscopy	Uniaxial extension of regenerated silk fibroin films increases their Young's modulus from 2.7 to 3.5 GPa	110 and 111
Electrical properties	Electrical conductivity or resistivity	Insulating but can be modified for conductivity using composites	Insulator; conductive properties enhanced when hybridized with graphene	Limited conductivity but can function as a dielectric layer	112, 113 and 114
Thermal properties	Thermal conductivity	Chitin nanofiber films exhibited in-plane thermal conductivity of 0.73–0.82 W m−1 K−1, with surface amino groups influencing conductivity	Nanocellulose filaments fabricated by flow-focusing can exhibit thermal conductivity up to 14.5 W m−1 K−1, much higher than cellulose nanopaper or nanocrystals	Single silk fibroin fibers exhibit an axial thermal conductivity of approximately 0.775 W m−1 K−1 at room temperature, which is significantly higher than most textile fibers	115–117
	Heat capacity	Not favourable	Moderate	Moderate	118–120
	Thermal stability	ChNFs start decomposing at 33 °C	Chemical pretreatments can enhance thermal properties, with NaOH/urea/thiourea-treated nanofibers demonstrating thermal degradation onset at 270 °C and maximum degradation at 370 °C	Silk fibroin decomposes at around 348 °C	121 and 122
	Thermal expansion coefficient	Low	Low	Slightly higher	123
Biological properties	Biocompatibility	ChNFs demonstrate excellent biocompatibility, promoting cell proliferation and collagen deposition, which are crucial for wound healing	Critical biocompatibility	Superior biocompatibility	124 and 125
	Antibacterial or antiviral activity	Chitin-based materials demonstrate over 99.95% bacteriostasis against pathogens like Staphylococcus aureus and Escherichia coli, making them effective in medical and civil applications	Its large surface area and porous structure facilitate effective interactions with bacteria, disrupting their membranes and inhibiting proliferation	Silk fibroin membranes combined with polyhexamethylene biguanide (PHMB) or silver oxide nanoparticles effectively inhibit Staphylococcus aureus and Escherichia coli	126–128
	Biodegradability	Chitin is highly biodegradable, breaking down into simple organic acids, which supports bacterial growth due to its favorable carbon : nitrogen ratio	Nanocellulose, derived from cellulose, is also biodegradable and exhibits excellent mechanical properties, making it suitable for various applications	Silk fibroin is known for its biocompatibility and biodegradability, although its degradation rate can be slower compared to chitin	129 and 130
Surface properties	Adsorption and desorption behavior	High for all-purpose	Medium to high	High for heavy metals	131 and 132
Environmental properties	Photocatalytic degradation of pollutants	Chitin-based composites, particularly when integrated with TiO2, exhibit improved photocatalytic activity due to reduced band gap energy and enhanced reactive sites	The three-dimensional structure of these aerogels provides a large surface area, promoting effective photocatalytic reactions through increased active sites	Combined with metal oxide nanoparticles like ZnO and TiO2, the degradation efficiency of various organic pollutants, including pesticides and dyes, is enhanced under solar irradiation	133–136
Water purification potential	Excellent adsorption properties for heavy metals in water treatment	Strong capability for dye and heavy metal removal	Moderate potential for water purification, enhanced with chemical modifications	Water purification potential is medium	137 and 138
Environmental stability	Stable in mildly acidic, basic, and oxidative conditions but degrade under extreme environments, such as strong oxidants or high temperatures	Highly stable in aqueous and neutral environments. Stability decreases under strongly acidic or basic conditions but can be enhanced by cross-linking	Stable in physiological environments but prone to enzymatic degradation in biological systems. Combining it with nanocellulose enhances its environmental stability	Environmental stability	139 and 140