Submicron-Grooved Films Modulate the Directional Alignment and Biological Function of Schwann Cells.

Topographical cues on material surfaces are crucial for guiding the behavior of nerve cells and facilitating the repair of peripheral nerve defects. Previously, micron-grooved surfaces have shown great potential in controlling nerve cell alignment for studying the behavior and functions of those cells and peripheral nerve regeneration. However, the effects of smaller-sized topographical cues, such as those in the submicron- and nano-scales, on Schwann cell behavior remain poorly understood. In this study, four different submicron-grooved polystyrene films (800/400, 800/100, 400/400, and 400/100) were fabricated to study the behavior, gene expression, and membrane potential of Schwann cells. The results showed that all submicron-grooved films could guide the cell alignment and cytoskeleton in a groove depth-dependent manner. Cell proliferation and cell cycle assays revealed that there was no significant difference between the submicron groove samples and the flat control. However, the submicron grooves can direct the migration of cells and upregulate the expression of critical genes in axon regeneration and myelination (e.g., MBP and Smad6). Finally, the membrane potential of the Schwann cells was significantly altered on the grooved sample. In conclusion, this study sheds light on the role of submicron-grooved patterns in regulating the behavior and function of Schwann cells, which provides unique insights for the development of implants for peripheral nerve regeneration.

Correction: Tuning the arrangement of lamellar nanostructures: achieving the dual function of physically killing bacteria and promoting osteogenesis.

Correction for 'Tuning the arrangement of lamellar nanostructures: achieving the dual function of physically killing bacteria and promoting osteogenesis' by Shi Mo et al., Mater. Horiz., 2023, 10, 881-888, https://doi.org/10.1039/d2mh01147f.

Tuning the arrangement of lamellar nanostructures: achieving the dual function of physically killing bacteria and promoting osteogenesis.

Bacteria killing behavior based on physical effects is preferred for biomedical implants because of the negligible associated side effects. However, our current understanding of the antibacterial activity of nanostructures remains limited and, in practice, nanoarchitectures that are created on orthopedics should also promote osteogenesis simultaneously. In this study, tilted and vertical nanolamellar structures are fabricated on semi-crystalline polyether-ether-ketone (PEEK) via argon plasma treatment with or without pre-annealing. The two types of nanolamellae can physically kill the bacteria that come into contact with them, but the antibacterial mechanisms between the two are different. Specifically, the sharp edges of the vertically aligned nanolamellae can penetrate and damage the bacterial membrane, whereas bacteria are stuck on the tilted nanostructures and are stretched, leading to eventual destruction. The tilted nanolamellae are more desirable than the vertically aligned ones from the perspective of peri-implant bone regeneration. Our study not only reveals the role of the arrangement of nanostructures in orthopedic applications but also provides new information about different mechanisms of physical antibacterial activity.

Reversibly Migratable Fluorescent Probe for Precise and Dynamic Evaluation of Cell Mitochondrial Membrane Potentials.

The mitochondrial membrane potential (MMP, ΔΨmito) provides the charge gradient required for mitochondrial functions and is a key indicator of cellular health. The changes in MMP are closely related to diseases and the monitoring of MMP is thus vital for pathological study and drug development. However, most of the current fluorescent probes for MMP rely solely on the cell fluorescence intensity and are thus restricted by poor photostability, rendering them not suitable for long-term dynamic monitoring of MMP. Herein, an MMP-responsive fluorescent probe pyrrolyl quinolinium (PQ) which is capable of reversible migration between mitochondria and nucleolus is developed and demonstrated for dynamic evaluation of MMP. The fluorescence of PQ translocates from mitochondria to nucleoli when MMP decreases due to the intrinsic RNA-specificity and more importantly, the translocation is reversible. The cytoplasm to nucleolus fluorescence intensity ratio is positively correlated with MMP so that this method avoids the negative influence of photostability and imaging parameters. Various situations of MMP can be monitored in real time even without controls. Additionally, long-term dynamic evaluation of MMP is demonstrated for HeLa cells using PQ in oxidative environment. This study is expected to give impetus to the development of mitochondria-related disease diagnosis and drug screening.