Dual-functional gold nanorods micro pattern guiding cell alignment and cellular microenvironment monitoring.

Surface topography has become a powerful tool to control cell behaviors, however, it's still difficult to monitor cellular microenvironment changes during topography-induced cell responses. Here, a dual-functional platform integrating cell alignment with extracellular pH (pHe) measurement is proposed. The platform is fabricated by assembling gold nanorods (AuNRs) into micro pattern via wettability difference interface method, which provides topographical cues and surface-enhanced Raman scattering (SERS) effect for cell alignment and biochemical detection respectively. Results demonstrate that contact guidance and cell morphology changes are achieved by the AuNRs micro pattern, and pHe are also obtained by the changes of SERS spectra during cell alignment, where the pHe near cytoplasm is lower than nucleus, revealing the heterogeneity of extracellular microenvironment. Moreover, a correlation between lower extracellular pH and higher cell migration ability is revealed, and AuNRs micro pattern can differentiate cells with different migration ability, which may be an inheritable character during cell division. Furthermore, mesenchymal stem cells response dramatically to AuNRs micro pattern, showing different morphology and increased pHe level, offering the potential of impacting stem cell differentiation. This approach provides a new idea for the research of cell regulation and response mechanism.