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Favorable polymer-substrate interactions induce surface orientation fields in block copolymer (BCP) melts. In linear BCP processed near equilibrium, alignment of domains generally persists for a small number of periods (∼4–6 D 0 ) before randomization of domain orientation. Bottlebrush BCP are an emerging class of materials with distinct chain dynamics stemming from substantial molecular rigidity, enabling rapid assembly at ultrahigh (>100 nm) domain periodicities with strong photonic properties (structural color). This work assesses interface-induced ordering in PS- b -PLA bottle b rush diblock copolymer films during thermal annealing between planar surfaces. To clearly observe the decay in orientational order from surface to bulk, we choose to study micron-scale films spanning greater than 200 lamellar periods. In situ optical microscopy and transmission UV-Vis spectroscopy are used to monitor photonic properties during annealing and paired with ex situ UV-Vis reflection measurement, cross-sectional scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS) to probe the evolution of domain microstructure. Photonic properties were observed to saturate within minutes of annealing at 150 °C, with distinct variation in transmission response as a function of film thickness. The depth of the highly aligned surface region was found to vary stochastically in the range of 30–100 lamellar periods, with the sharpness of the orientation gradient decreasing substantially with increasing film thickness. This observation suggests a competition between growth of aligned, heterogeneously nucleated, grains at the surface and orientationally isotropic, homogeneously nucleated, grains throughout the bulk. This work demonstrates the high potential of bottlebrush block copolymers in rapid fabrication workflows and provides a point of comparison for future application of directed self-assembly to BBCP ordering. 

Additive manufacturing of functional materials is limited by control of microstructure and assembly at the nanoscale. In this work, we integrate nonequilibrium self-assembly with direct-write three-dimensional (3D) printing to prepare bottlebrush block copolymer (BBCP) photonic crystals (PCs) with tunable structure color. After varying deposition conditions during printing of a single ink solution, peak reflected wavelength for BBCP PCs span a range of 403 to 626 nm (blue to red), corresponding to an estimated change in d-spacing of >70 nm (Bragg- Snell equation). Physical characterization confirms that these vivid optical effects are underpinned by tuning of lamellar domain spacing, which we attribute to modulation of polymer conformation. Using in situ optical microscopy and solvent-vapor annealing, we identify kinetic trapping of metastable microstructures during printing as the mechanism for domain size control. More generally, we present a robust processing scheme with potential for on-the-fly property tuning of a variety of functional materials. 

Brain organoids are miniaturized in vitro brain models generated from pluripotent stem cells, which resemble full‐sized brain more closely than conventional two‐dimensional cell cultures. Although brain organoids mimic the human brain's cell‐to‐cell network interactions, they generally fail to faithfully recapitulate cell‐to‐matrix interactions. Here, an engineered framework, called an engineered extracellular matrix (EECM), was developed to provide support and cell‐to‐matrix interactions to developing brain organoids.

We generated brain organoids using EECMs comprised of human fibrillar fibronectin supported by a highly porous polymer scaffold. The resultant brain organoids were characterized by immunofluorescence microscopy, transcriptomics, and proteomics of the cerebrospinal fluid (CSF) compartment.

The interstitial matrix‐mimicking EECM enhanced neurogenesis, glial maturation, and neuronal diversity from human embryonic stem cells versus conventional protein matrix (Matrigel). Additionally, EECMs supported long‐term culture, which promoted large‐volume organoids containing over 250 μL of CSF. Proteomics analysis of the CSF found it superseded previous brain organoids in protein diversity, as indicated by 280 proteins spanning 500 gene ontology pathways shared with adult CSF.

Engineered EECM matrices represent a major advancement in neural engineering as they have the potential to significantly enhance the structural, cellular, and functional diversity that can be achieved in advanced brain models.

 

The extracellular matrix (ECM) influences biological processes associated with tissue development and disease progression. However, robust cell‐free techniques to control fiber alignment of naturally derived ECM proteins, such as fibronectin (Fn), remain elusive. It is demonstrated that controlled hydrodynamics of Fn solutions at the air/fluid interface of porous tessellated polymer scaffolds (TPSs) generates suspended 3D fibrillar networks with alignment across multiple length scales (<1, 1–20 μm, extended to >1 mm). The direction of the fluid flow and the architecture of the polymeric supports influence protein solution flow profiles and, subsequently, the alignment of insoluble Fn fibrils. Aligned networks of fibrillar Fn characteristically alter fibroblast phenotype, indicated by increased directional orientation, enhanced nuclear and cytoskeletal polarity, and highly anisotropic and persistent cell motility when compared with nonaligned 3D networks and 2D substrates. Engineered extracellular matrices (EECMs) establish a critically needed tool for both fundamental and applied cell biology studies, with potential applications in diverse areas such as cancer biology and regenerative medicine.

 

This paper describes deterministic assembly processes for transforming conventional, planar devices based on flexible printed circuit board (FPCB) platforms into those with 3D architectures in a manner that is fully compatible with off‐the‐shelf packaged or unpackaged component parts. The strategy involves mechanically guided geometry transformation by out‐of‐plane buckling motions that follow from controlled forces imposed at precise locations across the FPCB substrate by a prestretched elastomer platform. The geometries and positions of cuts, slits, and openings defined into the FPCB provide additional design parameters to control the final 3D layouts. The mechanical tunability of the resulting 3D FPCB platforms, afforded by elastic deformations of the substrate, allows these electronic systems to operate in an adaptable manner, as demonstrated in simple examples of an optoelectronic sensor that offers adjustable detecting angle/area and a near‐field communication antenna that can be tuned to accommodate changes in the electromagnetic properties of its surroundings. These approaches to 3D FPCB technologies create immediate opportunities for designs in multifunctional systems that leverage state‐of‐the‐art components.