Polysaccharides are carbohydrate polymers that are major
components
of plants, animals, and microorganisms, with unique properties. Biological
hydrogels are polymeric networks that imbibe and retain large amounts
of water and are the major components of living organisms. The mechanical
properties of hydrogels are critical for their functionality and applications.
Since synthetic polymeric double-network (DN) hydrogels possess unique
network structures with high and tunable mechanical properties, many
natural functional polysaccharides have attracted increased attention
due to their rich and convenient sources, unique chemical structure
and chain conformation, inherently desirable cytocompatibility, biodegradability
and environmental friendliness, diverse bioactivities, and rheological
properties, which rationally make them prominent constituents in designing
various strong and tough polysaccharide-based DN hydrogels over the
past ten years. This review focuses on the latest developments of
polysaccharide-based DN hydrogels to comprehend the relationship among
the polysaccharide properties, inner strengthening mechanisms, and
applications. The aim of this review is to provide an insightful mechanical
interpretation of the design strategy of novel polysaccharide-based
DN hydrogels and their applications by introducing the correlation
between performance and composition. The mechanical behavior of DN
hydrogels and the roles of varieties of marine, microbial, plant,
and animal polysaccharides are emphatically explained.