nCycloparaphenylenes as Compatible Fluorophores for Melt Electrowriting

Abstract Fluorescent probes are an indispensable tool in the realm of bioimaging technologies, providing valuable insights into the assessment of biomaterial integrity and structural properties. However, incorporating fluorophores into scaffolds made from melt electrowriting (MEW) poses a challenge due to the sustained, elevated temperatures that this processing technique requires. In this context, ncycloparaphenylenes (nCPPs) serve as excellent fluorophores for MEW processing with the additional benefit of customizable emissions profiles with the same excitation wavelength. Three fluorescent blends are used with distinct nCPPs with emission wavelengths of either 466, 494, or 533 nm, identifying 0.01 wt% as the preferred concentration. It is discovered that nCPPs disperse well within poly(ε‐caprolactone) (PCL) and maintain their fluorescence even after a week of continuous heating at 80 °C. The nCPP‐PCL blends show no cytotoxicity and support counterstaining with commonly used DAPI (Ex/Em: 359 nm/457 nm), rhodamine‐ (Ex/Em: 542/565 nm), and fluorescein‐tagged (Ex/Em: 490/515 nm) phalloidin stains. Using different color nCPP‐PCL blends, different MEW fibers are sequentially deposited into a semi‐woven scaffold and onto a solution electrospun membrane composed of 8CPP‐PCL as a contrasting substrate for the 10CPP‐PCL MEW fibers. In general, nCPPs are potent fluorophores for MEW, providing new imaging options for this technology.