Table 3 Summary of crosslinking modes and properties of natural and synthetic polymer hydrogel scaffolds

Col/PDA/HA

Freeze drying

800 kPa

200 μm

[40]

HAMA/4-Arm PEG-ACLT

3D bio-printing; UV irradiation

[45]

GCS/DF-PEG

Self-healing

33.19 kPa

18.3%

200–400 μm

[48]

CS-alginate + HAp

TIPS

98–270 MPa

2.93 ± 1.63 × 104 μm²

[49]

SH/GO/CS/nHAP

Upper layer SH (EDC and NHS); upper layer CS/GO (ultrasonicated); SH/GO/CS/nHAP(freeze-dried)

Upper layer (0.28 ± 0.024 MPa); upper layer (0.38 ± 0.021 MPa)

High water absorption

15.1%

The upper layer (40–200 µm); the lower layer (30–100 µm)

[50]

CS-KGN/OSA

Room-temperature self-crosslinking

300 kPa

The water content is relatively low

7.8%

20 μm

[53]

HAChCS

LDI crosslinking

0.5–0.8 MPa

High water absorption

40 d (40%)

Macroporosity (≈200 μm) and microporosity (≈10 μm)

[54]

Naringin–BG hydrogels

Mix BG/SA solution and naringin/AG/SA solution

[58]

OSA–DA

Schiff base reduction method and oxidation of NaIO₄

[62]

US–SF

Ultrasonication

90.95–6.04 kPa

High water absorption

28 d (30%)

Porosity of 86%

[73]

MCS/MSF

UV irradiation

0.32 ± 0.07 MPa

8.79 ± 0.71

The porosity is slightly smaller

[75]

PEG [PRGF]

PRGF (freeze thawing); PEG [PRGF] (Room-temperature incubation)

9–10 d

[86]

PEGDA + GelMA/Alginate

Layered 3D printing PEGDA; PEGDA and GelMA/Alginate low-temperature crosslinking

10–14 MPa

High moisture content

The surface pore morphology is uniform

[93]

PLGA–g-(PCL₅)₃

(PLGA + oligo-PCL₅) TEG was added and mixed evenly, lyophilization

Greater than 0.60 MPa

20% degradation in seven weeks

237 ± 31 μm

[96]

BC–PVA–PAMPS

Freeze thawing; UV irradiation PAMPS

23.0 MPa

[101]

PVA–PMEDAH

PVA and PMEDAH mix; Freeze thawing

Diameters ranging from 1 μm to 300 nm

[102]

PVA/CS

Freeze thawing

The water content is above 85%

200–400 μm

[103]

PVA–PAAc

Freeze thawing; annealing

Fequilibrium water content 48 ± 2%

[104]