Table 2 Summary materials used in EV-loaded composite hydrogels for wound healing

Alginate

The most prevalent natural biopolymers, good biocompatibility, non-toxicity, low extraction cost, ease of gelation, high absorbency

[66]

Collagen

An abundant natural protein in the body, high water absorbency, enabling printing through precise control of pH and temperature, a natural receptor for cellular adhesion

[60]

Chitosan

High biocompatibility and biodegradability, antimicrobial properties, sustaining cell growth and proliferation, activating macrophages and inducing the release of cytokines, suitable for 3D bioprinting applications

[43, 62]

Cellulose

Diverse and tunable mechanical, structural, chemical, and physical properties, easily obtainable and cost-effective, high biocompatibility, biodegradability, and moisturizing attributes, facilitating the migration and proliferation of dermal fibroblasts while inhibiting bacterial proliferation

[43]

Silk fibroin

Excellent biocompatibility and biodegradability, promoting wound cell growth, differentiation, and extracellular matrix regeneration, mimicking the mechanical behavior of normal tissues

[36, 67]

Gelatin

Excellent biocompatibility, non-immunogenicity, good cell affinity, and degrades completely in vivo, promoting cell adhesion, thermosensitivity

[55]

Hyaluronic acid

The most common component in the ECM, promoting cell adhesion, migration, and proliferation, water-soluble property, suitable for bioprinting

[68]

Decellularized extracellular matrix

Preserving the structural and functional features of the ECM, facilitating cellular processes like adhesion and proliferation

[69]

PVA

Ionic responsiveness and easily tunable mechanical strengths

[70]

PU

Biodegradability and highly porous cryogels providing a matrix for cell migration

[46]

PEG

Great biocompatibility and biodegradability

[71]

PCL

Sufficient mechanical strength, easy for 3D bioprinting

[72]

PF127

Biocompatible, mild inflammatory properties, absorbing the secretions from the wound surface, maintaining a moist environment, heat-sensitive and injectable properties

[37, 73]