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Mieloch, et al.
due to the cylindrical shape of the sample, which was Acknowledgments
unsuitable for nanoindentation. This obstacle prevented
the comparison between more crystalline 3D-printed grids The authors would like to thank Itedale Namro Redwan,
Volodymyr Kuzmenko and Micheal Giersig for scientific
and raw material. Another factor that has to be taken into support. Open access was cofounded by Excellence
consideration is the nonhomogeneous dispersion of the Initiative - Research University program, Call No. 040
nanotubes, which may form clusters within the material, “Open Access,” grant 040/08/POB2/0001.
potentially affecting the measurement.
Biological assessment of the materials revealed an Funding
extraordinary improvement in human knee chondrocyte
proliferation and viability after the addition of BCNT. This work was supported by the National Center for
At 0.02 w/w% BCNT concentration, cells displayed Research and Development TECHMATSTRATEG-
an optimal morphology and enhanced proliferation. III/0027/2019-00 the National Science Centre UMO-
Interestingly, MWCNT addition also enhanced 2016/23/B/NZ7/01288 grants.
proliferation in comparison to pure PCL; however, cell Conflict of interest
morphology remained spherical, signifying nonoptimal
adhesion to the surface. We suspect two potential The authors declare no competing interests.
mechanisms responsible for the observed effect: (i)
Alterations of the surface zeta potential; and (ii) CNT Author contributions
protrusion from the polymer matrix, providing additional J.D.R. guided and supervised the project. A. A. M. designed
anchoring for the cells. In addition, the 3D printing and supervised the experiments. A. A. M., J.A.S., and J.D.R.
process forces the alignment of CNT along the principal conducted experiments and contributed intellectually to the
axis of the polymer extrusion, which coincides with scientific design of the project. A.A.M. and J.D.R. mentored
the direction of the chondrocytes’ filopodia projection, the technical part of the project; manuscript preparation
supporting the latter hypothesis. Unfortunately, no direct A.A.M and J.A.S.; manuscript edition J.D.R.
cause of the enhanced adhesion/proliferation has been
found. References
As mentioned previously, PCL is a biodegradable
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especially for potentially cytotoxic fillers. In theory,
however, this could be mitigated by rapid extracellular Optimized Construction of a Full Thickness Human Skin
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5. Conclusions 3. Hassanajili S, Karami-Pour A, Oryan A, et al., 2019,
Preparation and Characterization of PLA/PCL/HA
Our study evaluated BCNT and MWCNT as fillers for Composite Scaffolds Using Indirect 3D Printing for Bone
PCL nanocomposites, dedicated for 3D bioprinting and Tissue Engineering. Mater Sci Eng C, 104:109960.
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could be derived from this study: (i) CNT decreases the
roughness of the 3D-printed constructs; (ii) CNT increases 4. Zhang W, Ullah I, Shi L, et al., 2019, Fabrication and
the temperature of modulus crossover, Tc, and Tc onset; Characterization of Porous Polycaprolactone Scaffold
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(v) at high concentrations, CNT elicit cytotoxic effect and of Levan/Polycaprolactone/Gelatin Blends for Bone Tissue
render the material rather unsuitable for tissue engineering
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of PCL-based nanocomposites reinforced with CNT for Polym J, 119:426–37.
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