Engineered living materials have the potential for wide-ranging applications such as biosensing and treatment of diseases. Programmable cells provide the functional basis for living materials; however, their release into the environment raises numerous biosafety concerns. Current designs that limit the release of genetically engineered cells typically involve the fabrication of multilayer hybrid materials with submicrometer porous matrices. Nevertheless the stringent physical barriers limit the diffusion of macromolecules and therefore the repertoire of molecules available for actuation in response to communication signals between cells and their environment. Here, we engineer a novel living material entitled “Platform for Adhesin-mediated Trapping of Cells in Hydrogels” (PATCH). This technology is based on engineered E. coli that displays an adhesion protein derived from an Antarctic bacterium with a high affinity for glucose. The adhesin stably anchors E. coli in dextran-based hydrogels with large pore diameters (10–100 μm) and reduces the leakage of bacteria into the environment by up to 100-fold. As an application of PATCH, we engineered E. coli to secrete the bacteriocin lysostaphin which specifically kills Staphyloccocus aureus with low probability of raising antibiotic resistance. We demonstrated that living materials containing this lysostaphin-secreting E. coli inhibit the growth of S. aureus, including the strain resistant to methicillin (MRSA). Our tunable platform allows stable integration of programmable cells in dextran-based hydrogels without compromising free diffusion of macromolecules and could have potential applications in biotechnology and biomedicine.

Liquid‐Phase (Scanning) Transmission Electron Microscopy (LP‐(S)TEM) has become an essential technique to monitor nanoscale materials processes in liquids in real‐time. Due to the pressure difference between the liquid and the microscope vacuum, bending of the silicon nitride (SiNx) membrane windows generally occurs. This causes a spatially varying liquid layer thickness that makes interpretation of LP‐(S)TEM results difficult due to a locally varying achievable resolution and diffusion limitations. To mediate these difficulties, it is shown: 1) how to quantitatively map liquid layer thickness for any liquid at less than 0.01 e− Å−2 total dose; 2) how to dynamically modulate the liquid thickness by tuning the internal pressure in the liquid cell, co‐determined by the Laplace pressure and the external pressure. It is demonstrated that reproducible inward bulging of the window membranes can be realized, leading to an ultra‐thin liquid layer in the central window area for high‐resolution imaging. Furthermore, it is shown that the liquid thickness can be dynamically altered in a programmed way, thereby potentially overcoming the diffusion limitations towards achieving bulk solution conditions. The presented approaches provide essential ways to measure and dynamically adjust liquid thickness in LP‐(S)TEM experiments, enabling new experiment designs and better control of solution chemistry.

5 Stichting PAMM, Laboratory for pathology and medical microbiology, De Run 6250, 5504 DL Veldhoven 6 Laboratory of Physical Chemistry 7 Molecular biosensing for medical diagnostics 8 Laboratory of protein engineering 1-4, 6-8 : Abstract:Engineered living materials have the potential for wide-ranging applications such as biosensing and treatment of diseases. Programmable cells provide the functional basis for living materials, however, their release into the environment raises numerous biosafety concerns. Current designs that limit the release of genetically engineered cells typically involve the fabrication of multi-layer hybrid materials with sub-micron porous matrices. Nevertheless the stringent physical barriers limit the diffusion of macromolecules and therefore the repertoire of molecules available for actuation in response to communication signals between cells and their environment. Here, we engineer a first-of-its-kind living material entitled 'Platform for Adhesin-mediated Trapping of Cells in Hydrogels' (PATCH). This technology is based on engineered E. coli that displays an adhesion protein derived from an Antarctic bacterium with high affinity for glucose. The adhesin stably anchors E. coli in dextran-based hydrogels with large pore diameters (10-100 µm) and reduces the leakage of bacteria into the environment by up to 100-fold. As an application of PATCH, we engineered E. coli to secrete lysostaphin via the Type 1 Secretion System and demonstrated that living materials containing this E. coli inhibit the growth of S. aureus, including the strain resistant to methicillin (MRSA). Our tunable platform allows stable integration of programmable cells in dextran-based hydrogels without compromising free diffusion of macromolecules and could have potential applications in biotechnology and biomedicine. Introduction:Synthetic biology aims to design programmable cells that combine sensing and molecular computing operations with on-demand production of proteins that have a broad spectrum of therapeutic applications [1][2][3][4]. Engineered living materials (ELMs) integrate genetically engineered cells with free standing materials and represent a new class of environmentally responsive living devices with designer physicochemical and material properties [5][6][7]. Ideally, ELMs provide mechanical robustness to engineered cells, prevent their leakage to the environment and allow cells to be viable for extended periods of time. The containment of genetically-modified microorganisms (GMMs) within various materials has become a grand challenge for future synthetic biology applications [8]. To date, strategies for containing GMMs inside a living device are based on the physical confinement by multi-layer materials [9][10][11]. Hybrid micro-patterned devices combining layers of elastomer and microporous hydrogel enabled the exchange of information with surrounding environment via diffusion of chemical inducers and their sensing by GMMs while displaying high mechanical resilience [10]. Nevertheless, the low porosity ...

Skin-compatible printed stretchable conductors that combine a low gauge factor with a high durability over many strain cycles are still a great challenge. Here, a graphene nanoplatelet-based colloidal ink utilizing a skin-compatible thermoplastic polyurethane (TPU) binder with adjustable rheology is developed. Stretchable conductors that remain conductive even under 100% strain and demonstrate high fatigue resistance to cyclic strains of 20–50% are realized via printing on TPU. The sheet resistances of these conductors after drying at 120 °C are as low as 34 Ω □ –1 mil –1 . Furthermore, photonic annealing at several energy levels is used to decrease the sheet resistance to <10 Ω □ –1 mil –1 , with stretchability and fatigue resistance being preserved and tunable. The high conductivity, stretchability, and cyclic stability of printed tracks having excellent feature definition in combination with scalable ink production and adjustable rheology bring the high-volume manufacturing of stretchable wearables into scope.

Colloid supported lipid bilayers (CSLBs) are formed via the rupture and fusion of lipid vesicles to coat spherical colloidal particles. CSLBs are an emerging vector for the controlled self-assembly of colloids due to the ability to include additives into the bilayer, which influence the (a)specific interactions between particles. To evaluate the specificity of CSLB assembly, first a fundamental study on the tunability of the colloidal interaction and resulting colloidal stability of CSLBs without specific interactions is reported here. It was found that both fluid and gel CSLBs showed significant clustering and attraction, while the addition of steric stabilizers induced a profound increase in stability. The interactions were rendered attractive again by the introduction of depletion forces via the addition of free non-adsorbing polymers. The compositions of fluid and gel CSLBs with 5% membrane stabiliser were concluded to be optimal for further studies where both colloidal stability, and contrasting membrane fluidity are required. These experimental findings were confirmed semi-quantitatively by predictions using numerical self-consistent mean-field theory lattice computations.