“From Academia” features recent, relevant, close to commercialization academic publications in the space of healthcare 3D printing, 3D bioprinting, and related emerging technologies. In this issue, we included an article focusing on how a 3D printed lens using two-photon lithography can help with SRS microscopy, an imaging technique for living cells; an article on how silk nanofiber can improve extrusion-based 3D bioprinting; an article focusing on aspiration-assisted freeform bioprinting of cellular spheroid in yield stress gel.
3D-Printed high-NA catadioptric thin lens for suppression of XPM background in Stimulated Raman Scattering microscopy
Authored by Andrea Bertoncini, Sergey P. Laptenok, Luca Genchi, Vijayakumar P. Rajamanickam, Carlo Liberale. Journal of Biophotonics, 9 July 2020
Stimulated Raman Scattering (SRS) is a fast chemical imaging technique with remarkable bioscience applications. Cross Phase Modulation (XPM) is a ubiquitous nonlinear phenomenon that can create spurious background signals that render difficult a high‐contrast imaging in SRS measurements. The XPM‐induced signal is usually suppressed using high numerical aperture (NA) microscope objectives or condensers to collect the transmitted excitation beam. However, these high NA optics feature short working distances, hence they are not compatible with stage‐top incubators, that are necessary to perform live‐cell time‐lapse experiments in controlled environments. Here, we show a 3D printed high NA compact catadioptric lens that fits inside stage‐top incubators and allows the collection of XPM‐free SRS signals. The lens delivers SRS images and spectra with a quality comparable to a signal collection with a high‐NA microscope objective. We also demonstrate the compatibility of the 3D printed lens with other nonlinear microscopies usually associated with SRS in multimodal microscopes.
Authored by S.Sakai, A.Yoshii, S.Sakurai, K.Horii, O.Nagasuna. Materials Today Bio. September 2020
Here, we investigated the usefulness of silk fibroin nanofibers obtained via mechanical grinding of degummed silkworm silk fibers as an additive in bioinks for extrusion three-dimensional (3D) bioprinting of cell-laden constructs. The nanofibers could be sterilized by autoclaving, and addition of the nanofibers improved the shear thinning of polymeric aqueous solutions, independent of electric charge and the content of cross-linkable moieties in the polymers. The addition of nanofibers to bioinks resulted in the fabrication of hydrogel constructs with higher fidelity to blueprints. Mammalian cells in the constructs showed >85% viability independent of the presence of nanofibers. The nanofibers did not affect the morphologies of enclosed cells. These results demonstrate the great potential of silk fibroin nanofibers obtained via mechanical grinding of degummed silkworm silk fibers as an additive in bioinks for extrusion 3D bioprinting.
Authored by Bugra Ayan, Nazmiye Celik, Zhifeng Zhang, Kui Zhou, Myoung Hwan Kim, Dishary Banerjee, Yang Wu, Francesco Costanzo & Ibrahim T. Ozbolat. Nature Communications Physics. 16 October 2020
Bioprinting of cellular aggregates, such as tissue spheroids, to form three-dimensional (3D) complex-shaped arrangements, has posed a major challenge due to lack of robust, reproducible and practical bioprinting techniques. Here, we demonstrate 3D aspiration-assisted freeform bioprinting of tissue spheroids by precisely positioning them in self-healing yield-stress gels, enabling the self-assembly of spheroids for fabrication of tissues. The presented approach enables the traverse of spheroids directly from the cell media to the gel and freeform positioning of the spheroids on demand. We study the underlying physical mechanism of the approach to elucidate the interactions between the aspirated spheroids and the gel’s yield-stress during the transfer of spheroids from cell media to the gel. We further demonstrate the application of the proposed approach in the realization of various freeform shapes and self-assembly of human mesenchymal stem cell spheroids for the construction of cartilage and bone tissues.