The mechanical properties of cells and the extracellular environment they reside in are governed by a complex interplay of biopolymers. These biopolymers, which possess a wide range of stiffnesses, self-assemble into fibrous composite networks such as the cytoskeleton and extracellular matrix. They interact with each other both physically and chemically to create a highly responsive and adaptive mechanical environment that stiffens when stressed or strained. Here we show that hybrid networks of a synthetic mimic of biological networks and either stiff, flexible and semi-flexible components, even very low concentrations of these added components, strongly affect the network stiffness and/or its strain-responsive character. The stiffness (persistence length) of the second network, its concentration and the interaction between the components are all parameters that can be used to tune the mechanics of the hybrids. The equivalence of these hybrids with biological composites is striking.

Biomaterial-based scaffolds are promising tools for controlled immunomodulation. They can be applied as three dimensional (3D) culture systems in vitro, whereas in vivo they may be used to dictate cellular localization and exert spatiotemporal control over cues presented to the immune system. As such, scaffolds can be exploited to enhance the efficacy of cancer immunotherapies such as adoptive T cell transfer, in which localization and persistence of tumor-specific T cells dictates treatment outcome. Biomimetic polyisocyanopeptide (PIC) hydrogels are polymeric scaffolds with beneficial characteristics as they display reversible thermally-induced gelation at temperatures above 16°C, which allows for their minimally invasive delivery via injection. Moreover, incorporation of azide-terminated monomers introduces functional handles that can be exploited to include immune cell-modulating cues. Here, we explore the potential of synthetic PIC hydrogels to promote the in vitro expansion and in vivo local delivery of pre-activated T cells. We found that PIC hydrogels support the survival and vigorous expansion of pre-stimulated T cells in vitro even at high cell densities, highlighting their potential as 3D culture systems for efficient expansion of T cells for their adoptive transfer. In particular, the reversible thermo-sensitive behavior of the PIC scaffolds favors straightforward recovery of cells. PIC hydrogels that were injected subcutaneously gelated instantly in vivo, after which a confined 3D structure was formed that remained localized for at least 4 weeks. Importantly, we noticed no signs of inflammation, indicating that PIC hydrogels are non-immunogenic. Cells co-delivered with PIC polymers were encapsulated within the scaffold in vivo. Cells egressed gradually from the PIC gel and migrated into distant organs. This confirms that PIC hydrogels can be used to locally deliver cells within a supportive environment. These results demonstrate that PIC hydrogels are highly promising for both the in vitro expansion and in vivo delivery of pre-activated T cells. Covalent attachment of biomolecules onto azide-functionalized PIC polymers provides the opportunity to steer the phenotype, survival or functional response of the adoptively transferred cells. As such, PIC hydrogels can be used as valuable tools to improve current adoptive T cell therapy strategies.

2609wileyonlinelibrary.com at the moment. [ 2,7,8 ] While the order within an assembly (nanometer scale) is extremely high, when dispersed, most supramolecular materials form macroscopically isotropic assemblies. Moreover, spatial control at device dimensions is challenging. Examples where such control is highly benefi cial or even crucial for device performance are in optoelectronic devices [8][9][10] and in tissue engineering, where a macroscopically organized polymer scaffold is necessary for the growth of highly aligned tissue, such as muscle fi bers and neural tissue. [11][12][13][14] So far, different strategies toward macroscopic alignment of polymeric and supramolecular materials have been developed, including photolithography, [ 15,16 ] soft lithography, [ 3,16 ] electrospinning, [17][18][19] electric [20][21][22][23] and magnetic [ 24,25 ] fi eld alignment, as well as shear fl ow alignment. [ 9,11 ] These techniques all have demonstrated their benefi ts, but also strong limitations such as incompatibility with (aqueous) soft matter, low susceptibilities, and/or poor spatial control across multiple length scales.In this manuscript, we use liquid crystal (LC) templating with patternable substrates to obtain full spatial control in our self-assembled materials. This approach has numerous advantages: (i) it does not depend on specifi c interactions between the assembly and the template and thus it can be applied to a wide range of materials; (ii) any desired (hierarchical) structure can be imprinted on the substrate and reproduced in the assembly; (iii) the desired product can be (chemically) modifi ed after organization (in our case to generate optically active π-conjugated polymers); and (iv) the template can be removed which only leaves the functional material on the substrate. In nonaqueous solvents (bulk thermotropic liquid crystals), the concept of LC templating was demonstrated successfully [ 10,[26][27][28][29][30][31] but in aqueous solutions unidirectional alignment at large length scales is rarely realized, let alone locally controlled. [ 32 ] The limited success in water is related to the amphiphilic lyotropic LCs that are notoriously diffi cult to align on commonly used substrates such as rubbed polyimide. [ 33,34 ] In addition, these lyotropic LCs are incompatible with electric fi elds (because of dielectric and Joule heating as well electrochemical degradation), and they can interfere with the desired self-assembly process of a supramolecular material. [ 35 ] To overcome these disadvantages, we use a template of a lyotropic chromonic LC (LCLC) which is a rigid plank-like molecule Controlling the organization of functional supramolecular materials at both short and long length scales as well as creating hierarchical patterns is essential for many biological and electrooptical applications. It remains however an extremely challenging objective to date, particularly in water-based systems. In this work, it is demonstrated that water-processable self-assembling materials can be organized from mic...

Polymer brushes are extensively used for the preparation of bioactive surfaces. They form a platform to attach functional (bio)molecules and control the physicochemical properties of the surface. These brushes are nearly exclusively prepared from flexible polymers, even though much stiffer brushes from semiflexible polymers are frequently found in nature, which exert bioactive functions that are out of reach for flexible brushes. Synthetic semiflexible polymers, however, are very rare. Here, we use polyisocyanopeptides (PICs) to prepare high-density semiflexible brushes on different substrate geometries. For bioconjugation, we developed routes with two orthogonal click reactions, based on the strain-promoted azide–alkyne cycloaddition reaction and the (photoactivated) tetrazole–ene cycloaddition reaction. We found that for high brush densities, multiple bonds between the polymer and the substrate are necessary, which was achieved in a block copolymer strategy. Whether the desired biomolecules are conjugated to the PIC polymer before or after brush formation depends on the dimensions and required densities of the biomolecules and the curvature of the substrate. In either case, we provide mild, aqueous, and highly modular reaction strategies, which make PICs a versatile addition to the toolbox for generating semiflexible bioactive polymer brush surfaces.