Assessment of the Behaviors of an In Vitro Brain Model On-Chip under Shockwave Impacts.

Herein we report the assessment of the effects of shockwave (SW) impacts on adult rat hippocampal progenitor cell (AHPC) neurospheres (NSs), which are used as in vitro brain models, for enhancing our understanding of the mechanisms of traumatic brain injury (TBI). The assessment has been achieved by using culture dishes and a new microchip. The microchip allows the chemicals released from the brain models cultured inside the cell culture chamber under SW impacts to diffuse to the nanosensors in adjacent sensor chambers through built-in diffusion barriers, which are used to prevent the cells from entering the sensor chambers, thereby mitigating the biofouling issues of the sensor surface. Experiments showed the negative impact of the SW on the viability, proliferation, and differentiation of the cells within the NSs. A qPCR gene expression analysis was performed and appeared to confirm some of the immunocytochemistry (ICC) results. Finally, we demonstrated that the microchip can be used to monitor lactate dehydrogenase (LDH) released from the AHPC-NSs subjected to SW impacts. As expected, LDH levels changed when AHPC-NSs were injured by SW impacts, verifying this chip can be used for assessing the degrees of injuries to AHPC-NSs by monitoring LDH levels. Taken together, these results suggest the feasibility of using the chip to better understand the interactions between SW impacts and in vitro brain models, paving the way for potentially establishing in vitro TBI models on a chip.

Facile Process for Fabrication of Silicon Micro-Nanostructures of Different Shapes as Molds for Fabricating Flexible Micro-Nanostructures and Wearable Sensors.

We report a method to fabricate silicon micro-nanostructures of different shapes by tuning the number of layers and the sizes of self-assembled polystyrene beads, which serve as the mask, and by tuning the reactive ion etching (RIE) time. This process is simple, scalable, and inexpensive without using any sophisticated nanomanufacturing equipment. Specifically, in this work, we demonstrate the proposed process by fabricating silicon micro- or nanoflowers, micro- or nanobells, nanopyramids, and nanotriangles using a self-assembled monolayer or bilayer of polystyrene beads as the mask. We also fabricate flexible micro-nanostructures by using silicon molds with micro-nanostructures. Finally, we demonstrate the fabrication of bandage-type electrochemical sensors with micro-nanostructured working electrodes for detecting dopamine, a neurotransmitter related to stress and neurodegenerative diseases in artificial sweat. All these demonstrations indicate that the proposed process provides a low-cost, easy-to-use approach for fabricating silicon micro-nanostructures and flexible micro-nanostructures, thus paving a way for developing wearable micro-nanostructures enabled sensors for a variety of applications in an efficient manner.