Table 2.
Porous materials based on cellulose nanocrystals (CNC) and applied in regenerative medicine.
| Materials | Fabrication Method | Cell type | Application | Experimental conditions | Observations | Ref. |
|---|---|---|---|---|---|---|
| CNCa) | 3D printing | – | Tissue engineering | Nozzle diameter of 410 μm (22G), a flow rate of 70–120%, and a printing speed of 10–80 mm/s | Shear-induced alignment oriented the nanocrystal from 61 to 76% in the extrusion direction. Pore size: between 80 and 2125 μm. | [200] |
| CNC-chitosan | 3D printing | MC3T3-E1 pre-osteoblast | Bone tissue engineering | Nozzle diameter 610 μm (20 G), Extrusion pressure 12–20 kPa. Cell density 5 million/mL. The bioprinted scaffolds were incubated in DMEM in a 24-well tissue culture plate at 37 °C for 24 h. | The degree of shrinkage ranged between 30 and 34%. The scaffolds enhanced the osteogenic differentiation and collagen formation in ECM. | [201] |
| PLLA-CNC | 3D printing | MG-63 human osteosarcoma | Bone tissue engineering | The selective laser sintering optimized parameters were the spot size ∼200 μm, the laser power 7 W, the scanning speed 200 mm/s, and layer thickness of 150 μm. | The addition of 3 wt% CNC (nucleating agent) enhanced the compressive strength and modulus by 190% and 350%. | [191] |
| Alginate-gelatin-CNC | 3D printing | human bone-marrow-derived mesenchymal stem cells | Bone tissue engineering | Nozzle diameter 200 μm (27 G), printing pressure of 80–600 kPa, printing speed of 8 mm/s, printing temperature of 30 °C, print-bed temperature 6 °C | Effective load transfer from the polymer matrix to CNC (due to the larger interconnected network) significantly improved the mechanical performance. | [190] |
| Alginate-gelatin-CNC | 3D printing | Human bone marrow-derived mesenchymal stem | Tissue engineering | Cellulose nanocrystals (CNCs) from cotton pulps (10–20 nm width, 50–400 nm length, 12% solid content, crystalline index >70%), Nozzle diameter 200 μm (27 G), printing pressure of 100–500 kPa, printing speed of 5 mm/s, printing temperature of 35 °C, print-bed temperature 4 °C | CNC containing structures display enhanced mineralization efficiency and cell proliferation compared with the control sample | [189] |
| PEGDA-CNC | 3D printing | – | Tissue engineering | The digital light processing parameters included the projector intensity of 18 mW/cm2, the exposure time of each layer was 4 s, the thickness of each cured layer (curing layer thickness) was set at 100 μm | The properties of digitally light processed 3D composites can be tailored by curing time and layer thickness | [202] |
| Gelatin-bioactive glass- CNC | Freeze casting | L929-fibroblast | Bone tissue engineering | The structure was put into a refrigerator. under −20 °C for 24 h, and then lyophilized at −57 °C and 0.05 bar for 48 h | The addition of CNC, even in small amounts, has a considerable effect on the mechanical performance | [203] |
| Cross-linked CNC | Freeze casting | Saos-2 | Bone tissue engineering | All suspensions were frozen at −4 °C overnight to turn the suspension into a cryo-gel. The cryo-gels were then transferred into anhydrous ethanol for 5 days to form alco-gels. The alco-gels were placed inside of a critical point dryer and solvent exchanged with supercritical CO2 and gradually depressurized to ambient conditions to produce CNC aerogel. | No collapse of cryo-gels was observed during the solvent exchange, thereby making incremental ethanol exchanges unnecessary. Formation of hydroxyapatite layers, the proliferation of bone-like cells in vitro, and bone regeneration in vivo | [122] |
| Hydroxyapatite–CNC–silk fibroin | Freeze casting | MC3T3-E1 | Bone tissue engineering | The scaffolds were freeze-dried for 24 h in 48-well plate. Then the scaffolds were immersed in 90% (v/v) aqueous methanol solution for 30 min to induce a structural transition that generated the water-insoluble scaffolds. | The average pore size and porosity of the scaffolds were 110 ± 7.3 mm and 90 ± 6.2%, respectively. The calvarial bone defect in rat was healed during 12 weeks of scaffold implantation | [204] |
| PVA-ovalbumin–CNC– HA | Freeze casting | – | Bone tissue engineering | The polymer solution was poured into 24-well plate, and freezed at −40 °C for 12 h, followed by drying under vacuum at similar temperature for 5 days. | Most optimal composition PVA/OVA/CNCs/n-HA (20:05:10:15) exhibited promises for short term bone regeneration | [205] |
| Alginate- gelatin- CNC | Freeze casting | Mesenchymal stem | Cartilage tissue engineering | The scaffolds were freeze-dried at −75 °C for 24 h | Nanocomposites with 96% porosity with a modulus of 0.5 GPa (higher than natural cartilage) | [206] |
| CNC/CNF-alginate | Freeze casting | L929-fibroblast | Tissue repair and wound healing | The samples were frozen in liquid nitrogen (−196 °C) for 5 min, followed by a freeze-drying step at −50 °C for 48 h. The dried materials were then added to a bath of CaCl2 at 2 wt % for 24 h. Then, the gels were washed with distilled water and were frozen with liquid nitrogen and freeze-dried again. | ECM biomimetic structure with promising mechanical properties, bioadhesion, cytocompatibility | [207] |
| CNC/CNF-chitosan | Freeze casting | – | Tissue regeneration | The slurry was poured in a polytetrafluoroethylene tube and was sealed with a copper mold (bottom section). The mold was then placed on liquid nitrogen. The molds were equilibrated to 4 °C for 10 min before a cooling rate of either 10 or 1 °C/min was applied until the mold reached a temperature of −150 °C. The frozen slurries for 72 h at 0.008 mbar and a coil temperature of −85 °C. | Obtaining structures with high porosity and surface area with controllable pore alignment | [192] |
| CNC/CNF-PVA | Casting | Human corneal epithelial | Soft contact lenses and cornea regeneration implants | The cast gels were placed at −20 ᵒC for 24 h followed by at least 48 h dialysis with deionized water. | Structures with higher water content and biocompatibility compared with commercial contact lenses | [195,196] |
| Dental glass ionomer cement- CNC | Casting | – | Dental composites | In addition to 0.4 wt% CNC, the compressive strength and tensile strength improved by 110% and 161%, respectively. | [208] | |
| Crosslinked CNF/CNC-alginate | Casting | Human naso-septal chondrocytes | Cartilage tissue engineering | Crosslinking was performed at room temperature using 0.1 M, 0.5 M or 1.0 M calcium chloride (CaCl2). | Different crosslinking and sterilization conditions had a considerable impact on the microstructure architecture. | [194] |
| PCL-CNC | Casting and extrusion | Mouse preosteoblast | Bone tissue engineering | Prior to extrusion the caster films were placed in vacuum oven at 40 °C for 24 h | By the addition of 10 wt% CNC, the stiffness was doubled, and the ultimate tensile strength increased by 60% | [209] |
| HA-CNC | Casting | human mesenchymal | Bone tissue engineering | The hybrid structure was dried at ambient condition | The CNC-based nanohybrids from agro-waste were biocompatible, nontoxic, and it enhanced the calcium nodule growth | [193] |
| Cellulose acetatepropionate-CNC | Casting | – | Tissue engineering | After casting the suspension, a 0.3 T magnetic field was applied for 1 h at room temperature and the structures were kept for another 1 h without the magnetic field | Alignment of CNC under weak magnetic field effectively enhanced the mechanical performance (even at 0.2 wt% CNC addition) | [210] |
| Rosin-g-CNC | – | – | Antimicrobe structures | – | Strong and medium antibacterial activity was observed against Gram-negative and Gram-positive bacteria, respectively | [211] |
| Porphyrin-CNC | – | M. smegmatis, E. coli and S. aureus bacteria strains | Antimicrobe structures | – | Development of photobacterial materials with high efficiency against Gram-negative, Gram-positive, and mycobacterium | [212] |
| Polyrhodanine-CNC | – | HeLa (ATCC CCL-2) | Antimicrobe structures | – | Core-sheath antimicrobial nanoparticles with killing efficiency of over 95% E.coli and B. subtilis | [213] |
| CNF–CNC | Electrospinning | Human dental follicle | Artificial organ | The operating voltage of 20 kV, flow rate 0.03 mL/min, A steel rotating collector (6 cm in diameter) wrapped with aluminum foil was placed 10 cm away. The tangential velocity of the collector was set at 300 m/min | All cellulose nanocomposite with high fiber alignment. | [197] |
| PBS-CNC | Electrospinning | 3T3 fibroblast | Tissue engineering | The operating voltage of 20 kV, flow rate 1.0–2.0 mL/h and the distance between the electrodes was 18 cm. | The in vitro degradation displayed to increase from 4.5% for pure PBS to about 14% for PBS-CNC (3 wt% CNC) during 28 days. | [198] |
| PLA | Electrospinning | – | Short-term applications in the tissue engineering | The operating voltage of 15 kV, flow rate 1.5 mL/h and the distance between the electrodes was 20 cm. The obtained fibers were collected as mats, and were vacuum-dried at 80 °C for 24 h. | Improvement in heat resistance, tensile stress, young’s modulus, In vitro degradation | [153] |
| PAN-CNC | Electrospinning | – | Dental composites | The operating voltage of 17.2 kV, flow rate 2.0 mL/h and the distance between the electrodes was 20 cm. | The addition of 3 wt% CNC resulted in a significant increase in flexural and fracture strength. | [214] |
| PLA-CNC | Electrospinning | Human bone marrow-derived mesenchymal stem | Bone tissue engineering | The operating voltage 16 kV, distance between the electrodes 15 cm, and rolling speed of the collector was 2000 rpm. | Excellent biocompatibility and promising osteoinductivity was obtained according to in vivo studies during three weeks | [199] |
| PEG-g–CNC–PLA | Electrospinning | Human mesenchymal stem cells | Bone tissue engineering | The operating voltage of 20 kV, flow rate 0.5 mL/h and the distance between the electrodes was 15 cm, and 18 G blunt stainless-steel needle. The obtained fibers were collected as mats and were vacuum-dried at 80 °C for 24 h. | The addition of PEG improved the biocompatibility of the composite | [215] |
| MAH-g-PLA | Electrospinning | Adipose-derived mesenchymal stem | Bone tissue engineering | The operating voltage of 15 kV, flow rate 1.5 mL/h and the distance between the electrodes was 20 cm, The obtained fibers were collected as mats and were vacuum-dried at 80 °C for 24 h. | Improvement in heat resistance and tensile strength. Reduction in vitro degradation rate. Capable of supporting cell proliferation. | [155] |
| PCL-CNC | Electrospinning | – | Controlled drug delivery | The operating voltage of 17 kV, flow rate 0.9 mL/h and the distance between the electrodes was 16 cm. | Addition of CNC enhanced the tensile strength and modulus by 46% and 47% | [216] |
| Alginate- gelatin- CNC | Injectable hydrogel | 3T3 fibroblast/MC3T3-E1 osteoblast | Bone regeneration | Injection with 18 G nozzle followed by the addition of 10.5 mL 0.05 M ZnSO4 (ionic crosslinking). | The presence of CNC enhanced the hydrogel/cell interactions | [217] |
a)
CNC, cellulose nanocrystal; PLLA, Poly-l-lactic acid; PEGDA, Poly(ethylene glycol)diacrylate; PVA, Polyvinyl alcohol; HA, Hydroxyapatite; CNF, Cellulose nanofibrils; PCL, Polycaprolactone; PBS, Polybutylene succinate; PLA, Polylactic acid; PAN, Polyacrylonitrile; PEG, Polyethylene glycol; MAH, Maleic Anhydride. ECM, extracellular matrix.