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Author: Bhusari, Shardul × End date: 2024 × Has files: Yes × Version: publishedVersion ×

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Now showing 1 - 4 of 4
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    Encapsulation of bacteria in bilayer Pluronic thin film hydrogels: A safe format for engineered living materials
    (Amsterdam : Elsevier, 2023) Bhusari, Shardul; Kim, Juhyun; Polizzi, Karen; Sankaran, Shrikrishnan; del Campo, Aránzazu
    In engineered living materials (ELMs) non-living matrices encapsulate microorganisms to acquire capabilities like sensing or biosynthesis. The confinement of the organisms to the matrix and the prevention of overgrowth and escape during the lifetime of the material is necessary for the application of ELMs into real devices. In this study, a bilayer thin film hydrogel of Pluronic F127 and Pluronic F127 acrylate polymers supported on a solid substrate is introduced. The inner hydrogel layer contains genetically engineered bacteria and supports their growth, while the outer layer acts as an envelope and does not allow leakage of the living organisms outside of the film for at least 15 days. Due to the flat and transparent nature of the construct, the thin layer is suited for microscopy and spectroscopy-based analyses. The composition and properties of the inner and outer layer are adjusted independently to fulfil viability and confinement requirements. We demonstrate that bacterial growth and light-induced protein production are possible in the inner layer and their extent is influenced by the crosslinking degree of the used hydrogel. Bacteria inside the hydrogel are viable long term, they can act as lactate-sensors and remain active after storage in phosphate buffer at room temperature for at least 3 weeks. The versatility of bilayer bacteria thin-films is attractive for fundamental studies and for the development of application-oriented ELMs.
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    Regulating Bacterial Behavior within Hydrogels of Tunable Viscoelasticity
    (Weinheim : Wiley-VCH, 2022) Bhusari, Shardul; Sankaran, Shrikrishnan; del Campo, Aránzazu
    Engineered living materials (ELMs) are a new class of materials in which living organism incorporated into diffusive matrices uptake a fundamental role in material's composition and function. Understanding how the spatial confinement in 3D can regulate the behavior of the embedded cells is crucial to design and predict ELM's function, minimize their environmental impact and facilitate their translation into applied materials. This study investigates the growth and metabolic activity of bacteria within an associative hydrogel network (Pluronic-based) with mechanical properties that can be tuned by introducing a variable degree of acrylate crosslinks. Individual bacteria distributed in the hydrogel matrix at low density form functional colonies whose size is controlled by the extent of permanent crosslinks. With increasing stiffness and elastic response to deformation of the matrix, a decrease in colony volumes and an increase in their sphericity are observed. Protein production follows a different pattern with higher production yields occurring in networks with intermediate permanent crosslinking degrees. These results demonstrate that matrix design can be used to control and regulate the composition and function of ELMs containing microorganisms. Interestingly, design parameters for matrices to regulate bacteria behavior show similarities to those elucidated for 3D culture of mammalian cells.
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    Printed Degradable Optical Waveguides for Guiding Light into Tissue
    (Weinheim : Wiley-VCH, 2020) Feng, Jun; Zheng, Yijun; Bhusari, Shardul; Villiou, Maria; Pearson, Samuel; del Campo, Aránzazu
    Optogenetics and photonic technologies are changing the future of medicine. To implement light‐based therapies in the clinic, patient‐friendly devices that can deliver light inside the body while offering tunable properties and compatibility with soft tissues are needed. Here extrusion printing of degradable, hydrogel‐based optical waveguides with optical losses as low as 0.1 dB cm−1 at visible wavelengths is described. Core‐only and core‐cladding fibers are printed at room temperature from polyethylene glycol (PEG)‐based and PEG/Pluronic precursors, and cured by in situ photopolymerization. The obtained waveguides are flexible, with mechanical properties tunable within a tissue‐compatible range. Degradation times are also tunable by adjusting the molar mass of the diacrylate gel precursors, which are synthesized by linking PEG diacrylate (PEGDA) with varying proportions of DL‐dithiothreitol (DTT). The printed waveguides are used to activate photochemical and optogenetic processes in close‐to‐physiological environments. Light‐triggered migration of cells in a photoresponsive 3D hydrogel and drug release from an optogenetically‐engineered living material by delivering light across >5 cm of muscle tissue are demonstrated. These results quantify the in vitro performance, and reflect the potential of the printed degradable fibers for in vivo and clinical applications.
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    Regulating bacterial behavior within hydrogels of tunable viscoelasticity
    (New York : Cold Spring Harbor Laboratory, 2022) Bhusari, Shardul; Sankaran, Shrikrishnan; del Campo, Aránzazu
    Engineered living materials (ELMs) are a new class of materials in which living organism incorporated into diffusive matrices uptake a fundamental role in material’s composition and function. Understanding how the spatial confinement in 3D affects the behavior of the embedded cells is crucial to design and predict ELM’s function, regulate and minimize their environmental impact and facilitate their translation into applied materials. This study investigates the growth and metabolic activity of bacteria within an associative hydrogel network (Pluronic-based) with mechanical properties that can be tuned by introducing a variable degree of acrylate crosslinks. Individual bacteria distributed in the hydrogel matrix at low density form functional colonies whose size is controlled by the extent of permanent crosslinks. With increasing stiffness and decreasing plasticity of the matrix, a decrease in colony volumes and an increase in their sphericity is observed. Protein production surprisingly follows a different pattern with higher production yields occurring in networks with intermediate permanent crosslinking degrees. These results demonstrate that, bacterial mechanosensitivity can be used to control and regulate the composition and function of ELMs by thoughtful design of the encapsulating matrix, and by following design criteria with interesting similarities to those developed for 3D culture of mammalian cells.