- Email: [email protected]
Nanocrystal cellulose (NCC) as reinforcing agent for electrospun nanofibers
d e n t a l m a t e r i a l s 3 1 S ( 2 0 1 5 ) e1–e66
Fig. 1
Conclusion: TPO addition up to 50% to a CQ-amine-based composite presented similar curing profiles up to 2 mm in thickness, as well as reduced yellowing and color change after curing. Beyond 2 mm, TPO additions resulted in reduced curing efficiency. http://dx.doi.org/10.1016/j.dental.2015.08.141
element mapping with EDAX, X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). HDPSCs were cultured and characterized. Then, they were seeded into the scaffold and both cell viability and cytotoxic effect of scaffolding were evaluated. To study the clinical application of the constructs, a calvarias defect in rats was generated and the constructs implanted. The animals were sacrificed and the tissue analyze at different times. Results: We have successfully generated 3-D porous TCP/HDPSCs scaffolds with consistent cylindrical shape, showing macro and micropores homogeneously distributed and interconnected. The scaffolds displayed low cytotoxicity in vitro as high cell viability and proliferation were observed. The in vivo effects of the constructs studied by histological and radiological analysis showed good signs of mineralization in calvarias defect. Conclusion: As hypothesized, our results showed that TCP scaffold enhances the osteogenic differentiation of the HDPSCs and promotes bone formation in vivo. The TCP/HDPSCs construct seems to be a promising candidate for bone defect repair. However, for the future potential use of TCP/HDPSCs constructs in bone tissue engineering it is needed more knowledge of its molecular properties. http://dx.doi.org/10.1016/j.dental.2015.08.142 P7
P6
Nanocrystal cellulose (NCC) as reinforcing agent for electrospun nanofibers
Effect and application of 3D-Scaffolds in restoration of bone defects
B.U. Peres 1,∗ , H.A. Vidotti 2 , A.P. Manso 1 , F. Ko 1 , R.M. Carvalho 1
M. Martin Del Campo 1,∗ , K. Alvarado-Estrada 1 , L. Rojo 2 , J.G. Sampedro 1 , ˜ 1 , J. San Román 2 R. Rosales-Ibánez 1
Universidad Autónoma De San Luis Potosí UASLP, Mexico 2 Group of Biomaterials, Institute of Polymers, CSIC, Madrid, Spain Purpose: In the world, the treatment of bone fractures and skeletal defects in patients with osteo chronic degenerative diseases are between the most costly and devastating problems in the health system. Bone-graft substitutes have been developed as alternatives to autologous or allogeneic bone grafts. They consist of scaffolds made of synthetic or natural biomaterials, which promote the migration, proliferation and differentiation of bone cells, and bone regeneration. To generate a suitable scaffold for bone tissue regeneration, hydroxyapatite and calcium phosphate have been widely investigated mainly due to its prominent biological properties like osteoconduction and osteoinduction. We hypothesized that the design of a 3D scaffold embedded of TCP/Human Dental Pulp Stem Cells (HDPSCs) is an attractive method to develop a superior osteogenic construct. Such a construct would display a dual effect: the ability to remodel bone tissue while simultaneously stimulating osteoblast-mediated bone formation. Methods and materials: The designed scaffolds were characterized structurally by Scanning Electron Microscopy (SEM),
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1 University of British Columbia, Vancouver, Canada 2 University of São Paulo, Bauru, Brazil
Purpose: Nanocrystal cellulose (NCC) is a sustainable and recyclable particle with excellent mechanical properties that could be potentially useful to reinforce nanofibers and ultimately composites. In this study we tested the effects of NCC incorporation on the mechanical properties of electrospun Polyacrylonitrile (PAN) nanofibers. Methods and materials: 11 wt% PAN (MW 150,000) in dimethylformamide (DMF) solution was electrospun (Kato Tech, Japan) at 14.6 kVA and 20 cm from the collector drum. Non-functionalized NCC was added to the solution at 1–3 wt%. Suspensions were sonicated for 2 h (Misonix Sonicator 3000) before spinning. Fiber mats were collected on an aluminum foil and tested as-spun. Strips (5 cm × 0.5 cm) were cut from the mat in an orientation parallel (par) and perpendicular (per) to the rotational direction of the collector drum. Tensile tests were performed (KES-G1, Kato Tech, Japan) and ultimate tensile strength (UTS), Yield Strength (0.3%), Elastic Modulus (E) and Elongation at break (%) were calculated from stress/strain plots. Data were analyzed by multiple t-test and one-way ANOVA (a = 0.05). Results: Shown in Table 1. Conclusion: Addition of NCC resulted in increased UTS, E and YS of the nanofibers without compromising elongation at break. Fibers showed anisotropic behavior, with
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d e n t a l m a t e r i a l s 3 1 S ( 2 0 1 5 ) e1–e66
Table 1 – Effects of NCC on PAN nanofiber tensile properties. UTS (MPa) PAR
PER
10.68 (1.96)C 17.47 (1.40)A 14.84 (0.87)B 19.30 (0.97)A
0% NCC 1% NCC 2% NCC 3% NCC
E (GPa) PAR
14.60 (0.99)C* 19.39 (3.32)B 21.02 (2.53)AB* 23.62 (1.36)A*
0.14 (0.05)B 0.38 (0.18)A 0.25 (0.02)AB 0.30 (0.08)AB
YS (MPa) PER
0.34 (0.11)B* 0.72 (0.18)A 0.52 (0.21)AB* 0.61 (0.09)AB*
EB (%)
PAR
PER
PAR
PER
1.74 (0.23)B 5.72 (0.99)A 3.56 (0.16)AB 5.50 (0.23)A
3.88 (0.49)B * 8.65 (1.64)A* 8.97 (0.74)A* 9.65 (1.14)A*
47 (14)B 66 (5)A 72 (4)A 58 (3)AB
26 (2)B 28 (3)B* 40 (6)A* 29 (2)B*
Different letters (one-way ANOVA) indicate significant difference between the values for each property and orientation (p < 0.05). * (t-test) Indicate differences between PAR and PER for each NCC concentration for each property. Abbreviations: PAR: Parallel to rotatory drum axis; PER: Perpendicular; UTS: Ultimate tensile strength; E: Elastic modulus; YS: Yield strength; EB: Elongation at Break.
higher strength and E, at perpendicular orientation. NCC is a promising, sustainable candidate for reinforcing composite structures. http://dx.doi.org/10.1016/j.dental.2015.08.143 P8 Silica coated crystalline, non-silicate nanoparticles for improved hybrid biomaterials M.R. Kaizer 1,∗ , J.A. Rosa 1 , A.P.R. Gonc¸alves 1 , Y. Zhang 2 , S.S. Cava 1 , R.R. Moraes 1 1 2
Federal University of Pelotas, Brazil New York University, USA
Purpose: This study was designed to develop and characterize a silica coating method for crystalline, non-silicate nanoparticles (Al2 O3 , TiO2 , and ZrO2 ), enabling effective silanization and their use as reinforcing phase in hybrid biomaterials. Methods and materials: The silica coating was obtained by a sol–gel method, in which the particles were firstly dispersed in aqueous hydrochloric acid solution. Tetraethyl orthosilicate (TEOS) was added to the suspension in the proportion of 40 vol% relative to the volume of nanoparticles. The particles were then heat-treated in an air atmosphere oven (5 ◦ C/min up to 900 ◦ C dwell for 2 h). The nanopowders had their chemical and microstructural characteristics evaluated before and
after silica coating by means of EDS, XRD, BET, FE-SEM, and TEM. Results: Silicon was identified (EDS) only for powders submitted to the silica coating method. The higher the surface area (BET) of the nanopowders (Al > Ti > Zr), the higher the silicon content after silica coating. All three powders were initially below 100 nm (BET). After silica coating, all increased in particle size, yet only Ti particles were above 100 nm. Crystal size (XRD) also only increased for Ti. TEM indicated the presence of a silica shell around Zr and Al particles. Clusters of Ti particles embedded in a silica matrix were a common finding, while some discrete coated particles were also present. It was noticed by the FE-SEM that the particles of the three groups became highly instable after silica coating. This effect is seen by an uncontrolled fusing of particles, caused by the energy of the beam, resulting in 3D porous ceramic structure. Conclusion: In conclusion, the silica coating method proposed here is a viable and promising strategy for the use of crystalline, non-silicate nanoparticles as reinforcing phase of polymeric hybrid biomaterials. Formation of 3D porous ceramic structures was not the primary aim of this study; however, there is potential applicability for polymer infiltration and developing of hybrid biomaterials for CAD-CAM.Group names Al, Ti, Zr refers to the as-received nanoparticles, while AlS, TiS, ZrS refers to these nanoparticles after silica (S) coating method http://dx.doi.org/10.1016/j.dental.2015.08.144
Table 1 – Characterizations of the nanopowders: elemental composition (EDS), particle size and specific surface area (BET), crystal size and crystalline phases (XRD). EDS (wt%)
Al AlS Ti TiS Zr ZrS
EDS (atom%)
O
*
Si
O
*
Si
15.7 10.7 12.9 5.4 2.1 2.4
84.3 83.6 87.1 92.0 98.0 96.5
– 5.7 – 2.6 – 1.1
24.0 16.9 30.7 14.5 10.8 12.1
76.0 78.0 69.3 81.7 89.2 84.9
– 5.1 – 3.9 – 3.1
Surface area (m2 /g) 193.2 91.1 91.9 7.3 27.3 12.5
Particle size (nm) 8.4 17.8 16.7 209.5 37.3 81.2
The symbol (*) refers to Al, Ti, or Zr according to the material under evaluation.
Crystal size (nm) 4.7 5.2 25.1 88.5 32.9 36.2
Crystalline phases
Gamma 100% Gamma 99.99% + Quartz 0.1% Anatase 100% Anatase 97.2% + Rutile 2.7% + Quartz 0.1% Monoclinic 100% Monoclinic 99.99% + Quartz 0.1%
Fig. 1
Conclusion: TPO addition up to 50% to a CQ-amine-based composite presented similar curing profiles up to 2 mm in thickness, as well as reduced yellowing and color change after curing. Beyond 2 mm, TPO additions resulted in reduced curing efficiency. http://dx.doi.org/10.1016/j.dental.2015.08.141
element mapping with EDAX, X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). HDPSCs were cultured and characterized. Then, they were seeded into the scaffold and both cell viability and cytotoxic effect of scaffolding were evaluated. To study the clinical application of the constructs, a calvarias defect in rats was generated and the constructs implanted. The animals were sacrificed and the tissue analyze at different times. Results: We have successfully generated 3-D porous TCP/HDPSCs scaffolds with consistent cylindrical shape, showing macro and micropores homogeneously distributed and interconnected. The scaffolds displayed low cytotoxicity in vitro as high cell viability and proliferation were observed. The in vivo effects of the constructs studied by histological and radiological analysis showed good signs of mineralization in calvarias defect. Conclusion: As hypothesized, our results showed that TCP scaffold enhances the osteogenic differentiation of the HDPSCs and promotes bone formation in vivo. The TCP/HDPSCs construct seems to be a promising candidate for bone defect repair. However, for the future potential use of TCP/HDPSCs constructs in bone tissue engineering it is needed more knowledge of its molecular properties. http://dx.doi.org/10.1016/j.dental.2015.08.142 P7
P6
Nanocrystal cellulose (NCC) as reinforcing agent for electrospun nanofibers
Effect and application of 3D-Scaffolds in restoration of bone defects
B.U. Peres 1,∗ , H.A. Vidotti 2 , A.P. Manso 1 , F. Ko 1 , R.M. Carvalho 1
M. Martin Del Campo 1,∗ , K. Alvarado-Estrada 1 , L. Rojo 2 , J.G. Sampedro 1 , ˜ 1 , J. San Román 2 R. Rosales-Ibánez 1
Universidad Autónoma De San Luis Potosí UASLP, Mexico 2 Group of Biomaterials, Institute of Polymers, CSIC, Madrid, Spain Purpose: In the world, the treatment of bone fractures and skeletal defects in patients with osteo chronic degenerative diseases are between the most costly and devastating problems in the health system. Bone-graft substitutes have been developed as alternatives to autologous or allogeneic bone grafts. They consist of scaffolds made of synthetic or natural biomaterials, which promote the migration, proliferation and differentiation of bone cells, and bone regeneration. To generate a suitable scaffold for bone tissue regeneration, hydroxyapatite and calcium phosphate have been widely investigated mainly due to its prominent biological properties like osteoconduction and osteoinduction. We hypothesized that the design of a 3D scaffold embedded of TCP/Human Dental Pulp Stem Cells (HDPSCs) is an attractive method to develop a superior osteogenic construct. Such a construct would display a dual effect: the ability to remodel bone tissue while simultaneously stimulating osteoblast-mediated bone formation. Methods and materials: The designed scaffolds were characterized structurally by Scanning Electron Microscopy (SEM),
e65
1 University of British Columbia, Vancouver, Canada 2 University of São Paulo, Bauru, Brazil
Purpose: Nanocrystal cellulose (NCC) is a sustainable and recyclable particle with excellent mechanical properties that could be potentially useful to reinforce nanofibers and ultimately composites. In this study we tested the effects of NCC incorporation on the mechanical properties of electrospun Polyacrylonitrile (PAN) nanofibers. Methods and materials: 11 wt% PAN (MW 150,000) in dimethylformamide (DMF) solution was electrospun (Kato Tech, Japan) at 14.6 kVA and 20 cm from the collector drum. Non-functionalized NCC was added to the solution at 1–3 wt%. Suspensions were sonicated for 2 h (Misonix Sonicator 3000) before spinning. Fiber mats were collected on an aluminum foil and tested as-spun. Strips (5 cm × 0.5 cm) were cut from the mat in an orientation parallel (par) and perpendicular (per) to the rotational direction of the collector drum. Tensile tests were performed (KES-G1, Kato Tech, Japan) and ultimate tensile strength (UTS), Yield Strength (0.3%), Elastic Modulus (E) and Elongation at break (%) were calculated from stress/strain plots. Data were analyzed by multiple t-test and one-way ANOVA (a = 0.05). Results: Shown in Table 1. Conclusion: Addition of NCC resulted in increased UTS, E and YS of the nanofibers without compromising elongation at break. Fibers showed anisotropic behavior, with
e66
d e n t a l m a t e r i a l s 3 1 S ( 2 0 1 5 ) e1–e66
Table 1 – Effects of NCC on PAN nanofiber tensile properties. UTS (MPa) PAR
PER
10.68 (1.96)C 17.47 (1.40)A 14.84 (0.87)B 19.30 (0.97)A
0% NCC 1% NCC 2% NCC 3% NCC
E (GPa) PAR
14.60 (0.99)C* 19.39 (3.32)B 21.02 (2.53)AB* 23.62 (1.36)A*
0.14 (0.05)B 0.38 (0.18)A 0.25 (0.02)AB 0.30 (0.08)AB
YS (MPa) PER
0.34 (0.11)B* 0.72 (0.18)A 0.52 (0.21)AB* 0.61 (0.09)AB*
EB (%)
PAR
PER
PAR
PER
1.74 (0.23)B 5.72 (0.99)A 3.56 (0.16)AB 5.50 (0.23)A
3.88 (0.49)B * 8.65 (1.64)A* 8.97 (0.74)A* 9.65 (1.14)A*
47 (14)B 66 (5)A 72 (4)A 58 (3)AB
26 (2)B 28 (3)B* 40 (6)A* 29 (2)B*
Different letters (one-way ANOVA) indicate significant difference between the values for each property and orientation (p < 0.05). * (t-test) Indicate differences between PAR and PER for each NCC concentration for each property. Abbreviations: PAR: Parallel to rotatory drum axis; PER: Perpendicular; UTS: Ultimate tensile strength; E: Elastic modulus; YS: Yield strength; EB: Elongation at Break.
higher strength and E, at perpendicular orientation. NCC is a promising, sustainable candidate for reinforcing composite structures. http://dx.doi.org/10.1016/j.dental.2015.08.143 P8 Silica coated crystalline, non-silicate nanoparticles for improved hybrid biomaterials M.R. Kaizer 1,∗ , J.A. Rosa 1 , A.P.R. Gonc¸alves 1 , Y. Zhang 2 , S.S. Cava 1 , R.R. Moraes 1 1 2
Federal University of Pelotas, Brazil New York University, USA
Purpose: This study was designed to develop and characterize a silica coating method for crystalline, non-silicate nanoparticles (Al2 O3 , TiO2 , and ZrO2 ), enabling effective silanization and their use as reinforcing phase in hybrid biomaterials. Methods and materials: The silica coating was obtained by a sol–gel method, in which the particles were firstly dispersed in aqueous hydrochloric acid solution. Tetraethyl orthosilicate (TEOS) was added to the suspension in the proportion of 40 vol% relative to the volume of nanoparticles. The particles were then heat-treated in an air atmosphere oven (5 ◦ C/min up to 900 ◦ C dwell for 2 h). The nanopowders had their chemical and microstructural characteristics evaluated before and
after silica coating by means of EDS, XRD, BET, FE-SEM, and TEM. Results: Silicon was identified (EDS) only for powders submitted to the silica coating method. The higher the surface area (BET) of the nanopowders (Al > Ti > Zr), the higher the silicon content after silica coating. All three powders were initially below 100 nm (BET). After silica coating, all increased in particle size, yet only Ti particles were above 100 nm. Crystal size (XRD) also only increased for Ti. TEM indicated the presence of a silica shell around Zr and Al particles. Clusters of Ti particles embedded in a silica matrix were a common finding, while some discrete coated particles were also present. It was noticed by the FE-SEM that the particles of the three groups became highly instable after silica coating. This effect is seen by an uncontrolled fusing of particles, caused by the energy of the beam, resulting in 3D porous ceramic structure. Conclusion: In conclusion, the silica coating method proposed here is a viable and promising strategy for the use of crystalline, non-silicate nanoparticles as reinforcing phase of polymeric hybrid biomaterials. Formation of 3D porous ceramic structures was not the primary aim of this study; however, there is potential applicability for polymer infiltration and developing of hybrid biomaterials for CAD-CAM.Group names Al, Ti, Zr refers to the as-received nanoparticles, while AlS, TiS, ZrS refers to these nanoparticles after silica (S) coating method http://dx.doi.org/10.1016/j.dental.2015.08.144
Table 1 – Characterizations of the nanopowders: elemental composition (EDS), particle size and specific surface area (BET), crystal size and crystalline phases (XRD). EDS (wt%)
Al AlS Ti TiS Zr ZrS
EDS (atom%)
O
*
Si
O
*
Si
15.7 10.7 12.9 5.4 2.1 2.4
84.3 83.6 87.1 92.0 98.0 96.5
– 5.7 – 2.6 – 1.1
24.0 16.9 30.7 14.5 10.8 12.1
76.0 78.0 69.3 81.7 89.2 84.9
– 5.1 – 3.9 – 3.1
Surface area (m2 /g) 193.2 91.1 91.9 7.3 27.3 12.5
Particle size (nm) 8.4 17.8 16.7 209.5 37.3 81.2
The symbol (*) refers to Al, Ti, or Zr according to the material under evaluation.
Crystal size (nm) 4.7 5.2 25.1 88.5 32.9 36.2
Crystalline phases
Gamma 100% Gamma 99.99% + Quartz 0.1% Anatase 100% Anatase 97.2% + Rutile 2.7% + Quartz 0.1% Monoclinic 100% Monoclinic 99.99% + Quartz 0.1%