Engineering complex tissue-like microgel arrays for evaluating stem cell differentiation

Development of tissue engineering scaffolds with native-like biology and microarchitectures is a prerequisite for stem cell mediated generation of off-the-shelf-tissues. So far, the field of tissue engineering has not full-filled its grand potential of engineering such combinatorial scaffolds for engineering functional tissues. This is primarily due to the many challenges associated with finding the right microarchitectures and ECM compositions for optimal tissue regeneration. Here, we have developed a new microgel array to address this grand challenge through robotic printing of complex stem cell-laden microgel arrays. The developed microgel array platform consisted of various microgel environments that where composed of native-like cellular microarchitectures resembling vascularized and bone marrow tissue architectures. The feasibility of our array system was demonstrated through localized cell spreading and osteogenic differentiation of human mesenchymal stem cells (hMSCs) into complex tissue-like structures. In summary, we have developed a tissue-like microgel array for evaluating stem cell differentiation within complex and heterogeneous cell microenvironments. We anticipate that the developed platform will be used for high-throughput identification of combinatorial and native-like scaffolds for tissue engineering of functional organs

Multicomponent colloidal crystals that are tunable over large areas

We create colloidal crystal assemblies over large areas containing up to 4 different functionalised polystyrene and silica particles. The method utilises evaporation induced self-assembly from colloidal suspensions confined on a hydrophilic surface. The morphology of the crystals is tuned by the particle size ratio employed during assembly

Novel protein patterning techniques based on self-assembly of highly ordered polymer colloids

Abstract not available

Amine-functionalized magnetic nanocomposite particles for efficient immobilization of lipase: effects of functional molecule size on properties of the immobilized lipase

A cost-effective design of reusable enzyme-functionalized particles with better catalytic activity is of great scientific interest due to their applications in a wide range of catalytic reactions in several industrial processes. In this work, a systematic approach for preparing amine-functionalized magnetic nanocomposite particles through the surface modification of core/shell type Fe3O4 cluster@SiO2 particles by the small molecules of 3-(2-aminoethyl)aminopropyltrimethoxysilane (AAS) or the large molecules of polyethyleneimine (PEI) with two different molecular weights, as the support materials for enzyme immobilization, has been demonstrated. The functional nanocomposite particles were characterized by STEM, XRD, EDX, VSM, TGA, FTIR, oxygen elemental analysis and zeta potential measurement techniques. Lipase from Pseudomonas cepacia, chosen as a model enzyme, was covalently immobilized on glutaraldehyde-activated particles. The free and immobilized lipases were characterized by UV-vis, FTIR and CD spectroscopic methods. It has been shown that the size of the functional molecule has a significant effect on the concentration of binding sites on the particles and consequently on the lipase immobilization efficiency and loading capacity as well as the conformation and activity of the immobilized lipase. Resulting from the increased binding site concentration on the low and high molecular weight PEI-functionalized particles' surface, high lipase immobilization efficiencies (87 and 97%, respectively) and loading capacities (803 and 817 mg g−1, respectively) were obtained. Upon the immobilization of lipase, the activity, thermal and storage stability as well as reusability were improved under harsh reaction conditions in the order of the lipase immobilized on the low molecular weight PEI > high molecular weight PEI > AAS functionalized particles. This study offers insight into the design of functionalized magnetic particles for efficient immobilization of enzymes as well as improvement of the immobilized enzymes properties

Highly ordered chemical patterns for controlling proteins at interfaces using binary colloid crystals as templates

Abstract not available