Development of functionalised polyelectrolyte capsules using filamentous Escherichia coli cells

Biopolymer-Based Multilayer Capsules and Beads Made via Templating: Advantages, Hurdles and Perspectives

One of the undeniable trends in modern bioengineering and nanotechnology is the use of various biomolecules, primarily of a polymeric nature, for the design and formulation of novel functional materials for controlled and targeted drug delivery, bioimaging and theranostics, tissue engineering, and other bioapplications. Biocompatibility, biodegradability, the possibility of replicating natural cellular microenvironments, and the minimal toxicity typical of biogenic polymers are features that have secured a growing interest in them as the building blocks for biomaterials of the fourth generation. Many recent studies showed the promise of the hard-templating approach for the fabrication of nano- and microparticles utilizing biopolymers. This review covers these studies, bringing together up-to-date knowledge on biopolymer-based multilayer capsules and beads, critically assessing the progress made in this field of research, and outlining the current challenges and perspectives of these architectures. According to the classification of the templates, the review sequentially considers biopolymer structures templated on non-porous particles, porous particles, and crystal drugs. Opportunities for the functionalization of biopolymer-based capsules to tailor them toward specific bioapplications is highlighted in a separate section.

Novel nanomaterial-organism hybrids with biomedical potential

Instinctive hierarchically biomineralized structures of various organisms, such as eggs, algae, and magnetotactic bacteria, afford extra protection and distinct performance, which endow fragile organisms with a tenacious ability to adapt and survive. However, spontaneous formation of hybrid materials is difficult for most organisms in nature. Rapid development of chemistry and materials science successfully obtained the combinations of organisms with nanomaterials by biomimetic mineralization thus demonstrating the reproduction of the structures and functions and generation of novel functions that organisms do not possess. The rational design of biomaterial-organism hybridization can control biological recognition, interactions, and metabolism of the organisms. Thus, nanomaterial-organism hybrids represent a next generation of organism engineering with great potential biomedical applications. This review summarizes recent advances in material-directed organism engineering and is mainly focused on biomimetic mineralization technologies and their outstanding biomedical applications. Three representative types of biomimetic mineralization are systematically introduced, including external mineralization, internal mineralization, and genetic engineering mineralization. The methods involving hybridization of nanomaterials and organisms based on biomimetic mineralization strategies are described. These strategies resulted in applications of various nanomaterial-organism hybrids with multiplex functions in cell engineering, cancer treatment, and vaccine improvement. Unlike classical biological approaches, this material-based bioregulation is universal, effective, and inexpensive. In particular, instead of traditional medical solutions, the integration of nanomaterials and organisms may exploit novel strategies to solve current biomedical problems. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Influences of Adhesion Variability on the "Living" Dynamics of Filamentous Bacteria in Microfluidic Channels

Microfabricated devices have increasingly incorporated bacterial cells for microscale studies and exploiting cell-based functions in situ. However, the role of surface interactions in controlling the bacterial cell behavior is not well understood. In this study, microfluidic substrates of varied bacterial-binding affinity were used to probe the interaction-driven behavior of filamentous Escherichia coli. In particular, cell alignment under controlled shear flow as well as subsequent orientation and filamentation were compared between cells presenting distinct outer membrane phenotypes. We demonstrated that filaments retained position under flow, which allowed for dynamic single-cell monitoring with in situ elongation of over 100 μm for adherent cells. This maximum was not reached by planktonic cells and was, therefore, adhesion-dependent. The bound filaments initially aligned with flow under a range of flow rates and their continual elongation was traced in terms of length and growth path; analysis demonstrated that fimbriae-mediated adhesion increased growth rate, increased terminal length, as well as dramatically changed the adherent geometry, particularly buckling behavior. The effects to filament length and buckling were further exaggerated by the strongest, specificity-driven adhesion tested. Such surface-guided control of the elongation process may be valuable to yield interesting “living” filamentous structures in microdevices. In addition, this work may offer a biomedically relevant platform for further elucidation of filamentation as an immune-resistant morphology. Overall, this work should inspire broader exploration of microfabricated devices for the study and application of single bacterial cells.

S-Layer-Based Nanocomposites for Industrial Applications

This chapter covers the fundamental aspects of bacterial S-layers: what are S-layers, what is known about them, and what are their main features that makes them so interesting for the production of nanostructures. After a detailed introduction of the paracrystalline protein lattices formed by S-layer systems in nature the chapter explores the engineering of S-layer-based materials. How can S-layers be used to produce "industry-ready" nanoscale bio-composite materials, and which kinds of nanomaterials are possible (e.g., nanoparticle synthesis, nanoparticle immobilization, and multifunctional coatings)? What are the advantages and disadvantages of S-layer-based composite materials? Finally, the chapter highlights the potential of these innovative bacterial biomolecules for future technologies in the fields of metal filtration, catalysis, and bio-functionalization.

Spatio-Temporal Control of LbL Films for Biomedical Applications: From 2D to 3D

Introduced in the '90s by Prof. Moehwald, Lvov, and Decher, the layer-by-layer (LbL) assembly of polyelectrolytes has become a popular technique to engineer various types of objects such as films, capsules and free standing membranes, with an unprecedented control at the nanometer and micrometer scales. The LbL technique allows to engineer biofunctional surface coatings, which may be dedicated to biomedical applications in vivo but also to fundamental studies and diagnosis in vitro. Initially mostly developed as 2D coatings and hollow capsules, the range of complex objects created by the LbL technique has greatly expanded in the past 10 years. In this Review, the aim is to highlight the recent progress in the field of LbL films for biomedical applications and to discuss the various ways to spatially and temporally control the biochemical and mechanical properties of multilayers. In particular, three major developments of LbL films are discussed: 1) the new methods and templates to engineer LbL films and control cellular processes from adhesion to differentiation, 2) the major ways to achieve temporal control by chemical, biological and physical triggers and, 3) the combinations of LbL technique, cells and scaffolds for repairing 3D tissues, including cardio-vascular devices, bone implants and neuro-prosthetic devices.