No abstract

The core-shell structure nanofibers of poly(ethylene oxide)/chitosan have been electrospun from the homogeneous solution of chitosan (CS, as shell) and poly(ethylene oxide) (PEO, as core). The preparation process of core-shell structure was quite simple and efficient without any complex electrospinning setup or post-treatment. The core-shell structure and major component of each layer had been characterized by TEM and further supported by SEM, XRD, DSC, and EDS studies. The blending ratio of PEO and CS, molecular weight of chitosan, and temperature of electrospinning were thought to be the key influence factors on the formation of core-shell structure. Because of the chitosan outer layer and shell thickness being controllable, the core-shell structure nanofiber would show a potential application for the biomedical fields involving wound care and tissue engineering.

Three-dimensional bioprinting is an emerging technology for fabricating living 3D constructs, and it has shown great promise in tissue engineering. Bioinks are scaffold materials mixed with cells used by 3D bioprinting to form a required cell-laden structure. In this paper, a novel bioink made of gelatin methacrylamide (GelMA) and collagen (Col) doped with tyrosinase (Ty) is presented for the 3D bioprinting of living skin tissues. Ty has the dual function of being an essential bioactive compound in the skin regeneration process and also as an enzyme to facilitate the crosslink of Col and GelMA. Further, enzyme crosslinking together with photocrosslinking can enhance the mechanical strength of the bioink. The experimental results show that the bioink is able to form stable 3D living constructs using the 3D bioprinting process. The cell culture shows that three major cell lines: human melanocytes (HEM), human keratinocytes (HaCat) and human dermal fibroblasts (HDF) exhibit high cell viabilities. The viability of these three cell lines is above 90%. The proliferation and scratching test show that Ty can enhance the proliferation of HEM, inhibit the growth and migration of HDF and not affect HaCat significantly. Animal tests show that the doped bioinks for 3D bioprinting can help form an epidermis and dermis, and thus have high potential as a skin bioink.

Internet of things (IoT) is expected to significantly improve every aspect of society, especially in soft robotics, structural health monitoring, and human motion detection. Flexible strain sensors with high‐performance characteristics as well as highly efficient and cost‐effective maskless fabrication methods are the key components of IoT for these applications. Herein, a 3D printing technology using digital light processing is developed to fabricate high‐performance flexible strain sensors based on UV‐curable multiwalled carbon nanotubes/elastomer (MWCNT/EA) composite. The MWCNT/EA‐based device with 2 wt% MWCNTs delivers a sensitivity of 8.939 with a linearity up to 45% strain. Additionally, the sensor has a detectable strain range from 0.01% to 60%, a high mechanical durability (10 000 cycles), and linear responses to humidity and temperature. Numerical simulation and impedance study indicate that the sensor works on the deformation‐induced reduction of MWCNT conductive pathway. The developed device can be used to detect various external deformation, when combined with a near‐field communication circuit. Moreover, a 4 × 4 strain sensor array is developed for sensing external stimuli distribution, further demonstrating the high performance of the 3D printed device.

The function and susceptibility of various drugs are tested with renal proximal tubular epithelial cells; yet, replicating the morphology and kidneys function using the currently available in vitro models remains difficult. To overcome this difficulty, in the study presented in this paper, a device and a threelayer microfluidic chip were developed, which provides a simulated environment for kidney organs. This device includes two parts: (1) microfluidic drug concentration gradient generator and (2) a flowtemperature controlled platform for culturing of kidney cells. In chip study, renal proximal tubular epithelial cells (RPTECs) and peritubular capillary endothelial cells (PCECs) were screened with the drugs to assess the drug-induced nephrotoxicity. Unlike cells cultured in petri dishes, cells cultured in the microfluidic device exhibited higher performance in terms of both cell growth and drug nephrotoxicity evaluation. It is worth mentioning that a significant decrease in cisplatin-induced nephrotoxicity was found because of the intervention of cimetidine in the microfluidic device. In conclusion, the different in the cell performance between the microfluidic device and the petri dishes demonstrates the physiological relevance of the nephrotoxicity screening technology along with the microfluidic device developed in this study. Furthermore, this technology can also facilitate the development of reliable kidney drugs and serve as a useful and efficient test-bed for further investigation of the drug nephrotoxicity evaluation.