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The construction of ordered nanoparticle arrays is important for nanophotonics and sensing applications. We report a facile technology for continuous-flow fabrication of particle-laden plasmonic microcapsules (PLPMs) by combining droplet microfluidics, nanoparticle self-assembly and thin film deposition. The metallic hierarchical nanostructures on PLPMs are presented with high-density "hot-spot" scattering sites with the nanoarray pitch and gap distance being controlled by the deposited metal film thickness and nanoparticle size. The noble metal "hot-spots" show high, localized surface plasmon resonance according to the near-field electromagnetic field enhancement. Surface-enhanced Raman scattering (SERS) analytical enhancement factors of >10 7 can be obtained with good reproducibility using 4-methylbenzenethiol (4-MBT) as a probe molecule and Au or Ag as the metal layer. The droplet microfluidics platform enables continuous generation of homogeneous microcapsules with high frequency. This proposed strategy therefore combines advantages from both top-down (creation of microdroplets and deposition of the metal film) and bottom-up (self-assembly of nanoparticles) processes with flexibility in material selection (nanoparticles and polymer) and structure scaling (metal layer thickness, nanoparticle size and microcapsule size). Therefore, it provides a fast and reliable method of producing plasmonic microsensors.

Pathologic thrombosis kills more people than cancer and trauma combined; it is associated with significant disability and morbidity, and represents a major healthcare burden. Despite advancements in medical therapies and imaging, there is often incomplete resolution of the thrombus. The residual thrombus can undergo fibrotic changes over time through infiltration of fibroblasts from the surrounding tissues and eventually transform into a permanent clot often associated with post-thrombotic syndrome. In order to understand the importance of cellular interactions and the impact of potential therapeutics to treat thrombosis, an in vitro platform using human cells and blood components would be beneficial. Towards achieving this aim, there have been studies utilizing the capabilities of microdevices to study the hemodynamics associated with thrombosis. In this work, we further exploited the utilization of 3D bioprinting technology, for the construction of a highly biomimetic thrombosis-on-a-chip model. The model consisted of microchannels coated with a layer of confluent human endothelium embedded in a gelatin methacryloyl (GelMA) hydrogel, where human whole blood was infused and induced to form thrombi. Continuous perfusion with tissue plasmin activator led to dissolution of non-fibrotic clots, revealing clinical relevance of the model. Further encapsulating fibroblasts in the GelMA matrix demonstrated the potential migration of these cells into the clot and subsequent deposition of collagen type I over time, facilitating fibrosis remodeling that resembled the in vivo scenario. Our study suggests that in vitro 3D bioprinted blood coagulation models can be used to study the pathology of fibrosis, and particularly, in thrombosis. This versatile platform may be conveniently extended to other vascularized fibrotic disease models.