Printable Organic Electronic Materials for Precisely Positioned Cell Attachment.

Over the past 3 decades, there has been a vast expansion of research in both tissue engineering and organic electronics. Although the two fields have interacted little, the materials and fabrication technologies which have accompanied the rise of organic electronics offer the potential for innovation and translation if appropriately adapted to pattern biological materials for tissue engineering. In this work, we use two organic electronic materials as adhesion points on a biocompatible poly(p-xylylene) surface. The organic electronic materials are precisely deposited via vacuum thermal evaporation and organic vapor jet printing, the proven, scalable processes used in the manufacture of organic electronic devices. The small molecular-weight organics prevent the subsequent growth of antifouling polyethylene glycol methacrylate polymer brushes that grow within the interstices between the molecular patches, rendering these background areas both protein and cell resistant. Last, fibronectin attaches to the molecular patches, allowing for the selective adhesion of fibroblasts. The process is simple, reproducible, and promotes a high yield of cell attachment to the targeted sites, demonstrating that biocompatible organic small-molecule materials can pattern cells at the microscale, utilizing techniques widely used in electronic device fabrication.

Single-shot terahertz time-domain spectroscopy in pulsed high magnetic fields.

We have developed a single-shot terahertz time-domain spectrometer to perform optical-pump/terahertz-probe experiments in pulsed, high magnetic fields up to 30 T. The single-shot detection scheme for measuring a terahertz waveform incorporates a reflective echelon to create time-delayed beamlets across the intensity profile of the optical gate beam before it spatially and temporally overlaps with the terahertz radiation in a ZnTe detection crystal. After imaging the gate beam onto a camera, we can retrieve the terahertz time-domain waveform by analyzing the resulting image. To demonstrate the utility of our technique, we measured cyclotron resonance absorption of optically excited carriers in the terahertz frequency range in intrinsic silicon at high magnetic fields, with results that agree well with published values.