Satellite-Based On-Orbit Printing of 3D Tumor Models.

Space three dimension (3D） bioprinting provides a precise and bionic tumor model for evaluating the compound effect of the space environment on tumors, thereby providing insight into the progress of the disease and potential treatments. However, space 3D bioprinting faces several challenges, including prelaunch uncertainty, possible liquid leakage, long-term culture in space, automatic equipment control, data acquisition, and transmission. Here, a novel satellite-based 3D bioprinting device with high structural strength, small volume, and low weight (<6 kg) is developed. A microgel-based biphasic thermosensitive bioink and suspension medium that supports the on-orbit printing and in situ culture of complex tumor models is developed. An intelligent control algorithm that enables the automatic control of 3D printing, autofocusing, fluorescence imaging, and data transfer back to the ground is developed. To the authors' knowledge, this is the first time that on-orbit printing of tumor models is achieved in space with stable morphology and moderate viability via a satellite. It is found that 3D tumor models are more sensitive to antitumor drugs in space than on Earth. This study opens up a new avenue for 3D bioprinting in space and offers new possibilities for future research in space life science and medicine.

Advances in digital light processing of hydrogels.

Hydrogels, three-dimensional (3D) networks of hydrophilic polymers formed in water, are a significant type of soft matter used in fundamental and applied sciences. Hydrogels are of particular interest for biomedical applications, owing to their soft elasticity and good biocompatibility. However, the high water content and soft nature of hydrogels often make it difficult to process them into desirable solid forms. The development of 3D printing (3DP) technologies has provided opportunities for the manufacturing of hydrogels, by adopting a freeform fabrication method. Owing to its high printing speed and resolution, vat photopolymerization 3DP has recently attracted considerable interest for hydrogel fabrication, with digital light processing (DLP) becoming a widespread representative technique. Whilst acknowledging that other types of vat photopolymerization 3DP have also been applied for this purpose, we here only focus on DLP and its derivatives. In this review, we first comprehensively outline the most recent advances in both materials and fabrication, including the adaptation of novel hydrogel systems and advances in processing (e.g. volumetric printing and multimaterial integration). Secondly, we summarize the applications of hydrogel DLP, including regenerative medicine, functional microdevices, and soft robotics. To the best of our knowledge, this is the first time that either of these specific review focuses has been adopted in the literature. More importantly, we discuss the major challenges associated with hydrogel DLP and provide our perspectives on future trends. To summarize, this review aims to aid and inspire other researchers investigatng DLP, photocurable hydrogels, and the research fields related to them.

A heart-on-a-chip platform for online monitoring of contractile behavior via digital image processing and piezoelectric sensing technique.

Heart-on-a-chip devices have recently emerged as a viable and promising model for drug screening applications, owing to its capability of capturing important biological and physiological parameters of cardiac tissue. However, most heart-on-a-chips are not developed for online and continuous monitoring of contractile behavior, which are the main functional characteristics of cardiac tissue. In this study, we designed and investigated on a heart-on-a-chip platform that provides online monitoring of contractile behavior of a 3D cardiac tissue construct. The contractile behavior include contraction force, frequency, and synchronization. They can be evaluated by an image processing system and a piezoelectric sensing system simultaneously. Based on the deformation of a micro-pillar array embedded within the 3D cardiac tissue upon subjected to cardiac contraction, the image processing system provides in situ multi-site detection of the contractile behavior. At the same time, the piezoelectric sensing system measures the contractile behavior of the entire cardiac tissue construct. A 3D cardiac tissue construct was successfully fabricated. Then the heart-on-a-chip platform was validated by applying various motion patterns on the micro-pillars, which mimicked the contraction patterns of the 3D cardiac tissue. The drug reactivity of the 3D cardiac tissue construct after a treatment of isoproterenol and doxorubicin was evaluated by measuring the contractile behavior via the image processing and the piezoelectric sensing systems. The results from the drug reactivity provided by both these measurement systems were consistent with previous reports, demonstrating the reliability of the heart-on-a-chip platform and its potential for use in cardio-related drug screening applications.