Self-decorating cells via surface-initiated enzymatic controlled radical polymerization

Through the innovative use of surface-displayed horseradish peroxidase, this work explores the enzymatic catalysis of both bioRAFT polymerization and bioATRP to prompt polymer synthesis on the surface of Saccharomyces cerevisiae cells, with bioATRP outperforming bioRAFT polymerization. The resulting surface modification of living yeast cells with synthetic polymers allows for a significant change in yeast phenotype, including growth profile, aggregation characteristics, and conjugation of non-native enzymes to the clickable polymers on the cell surface, opening new avenues in bioorthogonal cell-surface engineering

Pushing the limits of nanopore transport performance by polymer functionalization

Inspired by the design and performance of biological pores, polymer functionalization of nanopores has emerged as an evolving field to advance transport performance within the last few years. This feature article outlines developments in nanopore functionalization and the resulting transport performance including gating based on electrostatic interaction, wettability and ligand binding, gradual transport controlled by polymerization as well as functionalization-based asymmetric nanopore and nanoporous material design going towards the transport direction. Pushing the limits of nanopore transport performance and thus reducing the performance gap between biological and technological pores is strongly related to advances in polymerization chemistry and their translation into nanopore functionalization. Thereby, the effect of the spatial confinement has to be considered for polymer functionalization as well as for transport regulation, and mechanistic understanding is strongly increased by combining experiment and theory. A full mechanistic understanding together with highly precise nanopore structure design and polymer functionalization is not only expected to improve existing application of nanoporous materials but also opens the door to new technologies. The latter might include out of equilibrium devices, ionic circuits, or machine learning based sensors

Rational design of gold nanorod-based surface-enhanced raman scattering tags for near-infrared bio Sensing

Surface-enhanced Raman spectroscopy (SERS) represents a powerful analytical technique with a great promise for ultrasensitive bio analysis and detection. SERS tags are the new generation of nanoprobe offering remarkable features such as high signal uniformity, great physical and optical robustness and excellent multiplexing capability for indirect identification of the targets. Nevertheless, there are still plenty of opportunities and challenges to improve the performance of such assays. In this regard, anisotropic gold nanoparticles are potential candidates as they can support much stronger signal enhancement than those of commonly used sphere nanoparticles. Gold nanorod (NRs) in particular is a classic example of anisotropic nanostructure possessing unique properties including strong plasmonic effect, optical tunability as well as the capability for preferential surface modification.The motivation of this thesis is to develop a high-performance SERS tag for NIR detection of food-borne pathogenic bacteria. At the first step gold NRs with a similar optical absorption as the NIR laser, which is excitation source for cheap and portable Raman instruments, were prepared in order to achieve strong enhancement effect. At the second Chapter, as-synthesized gold NRs were rationally designed on the surface to provide the tags with the optimum signal enhancement and performance. In this regard, Raman reporter molecules were selectively attached to the NRs tips, where the local electromagnetic field is effectively concentrated. The side-body of encoded NRs was subsequently modified by attaching a mixed layer of two carboxyl terminated ligands aiming to improve colloidal stability as well as the coupling efficiency of the targeting moiety (bacteria antibody). In the last Chapter, performance of the tag was investigated for identification of Salmonella as one of the most common cause of food-related hospitalizations and deaths. In addition, the selective design of the tag was employed in preparation of two other tip-encoded NRs tags with distinctive Raman signatures. The multiplexing capability of the developed probes was examined for simultaneous detection of Salmonella typhimurium and other pathogenic bacteria including Staphylococcus aureus and E. coli O157:H7. Moreover, the specificity of the tags toward the target bacteria was also evaluated in food matrices prepared from chicken meat and leafy vegetables

PEO-b-PNBA in-situ functionalized mesoporous silica films and their light- and pH-controlled ionic mesopore accessibility

Multistimuli-responsive, in-situ functionalized mesoporous silica films were fabricated by evaporation-induced self-assembly through physical entrapment of the functional template poly(ethylene oxide)-b-poly(2-nitrobenzyl acrylate) (PEO-b-PNBA). The light-cleavable and pH-responsive block copolymer PEO-b-PNBA simultaneously serves as structure-directing agent and for in-situ polymer functionalization of the generated mesopore space. The use of different PEO-b-PNBA compositions results in highly filled hybrid mesoporous silica films with different pore sizes, porosity, and polymer chain sequence within the mesopores. Based on these structural variations and the polymer chain sequence the ionic permselectivity of the silica-polymer hybrid thin films is adjusted. The side chains of the template PNBA block can be deprotected upon irradiation, hereby releasing pH-responsive carboxylic acid groups. The irradiation energy and irradiation time-dependent deprotection allows gradually controlled charge regulation in mesopores. This approach of in-situ functionalization using multistimuli-responsive PEO-b-PNBA block copolymers facilitates the fabrication of multi-responsive hybrid mesoporous silica films and bears high potential for the production of complex, hierarchical, multifunctional mesoporous materials. This fabrication method including direct functionalization of mesoporous structures is of high interest for many applications based on controlled molecular transport in nanoscale pores, such as sensing, separation, or catalysis

PEO-b-PNBA in-situ functionalized mesoporous silica films and their light- and pH-controlled ionic mesopore accessibility

Multistimuli-responsive, in-situ functionalized mesoporous silica films were fabricated by evaporation-induced self-assembly through physical entrapment of the functional template poly(ethylene oxide)-b-poly(2-nitrobenzyl acrylate) (PEO-b-PNBA). The light-cleavable and pH-responsive block copolymer PEO-b-PNBA simultaneously serves as structure-directing agent and for in-situ polymer functionalization of the generated mesopore space. The use of different PEO-b-PNBA compositions results in highly filled hybrid mesoporous silica films with different pore sizes, porosity, and polymer chain sequence within the mesopores. Based on these structural variations and the polymer chain sequence the ionic permselectivity of the silica-polymer hybrid thin films is adjusted. The side chains of the template PNBA block can be deprotected upon irradiation, hereby releasing pH-responsive carboxylic acid groups. The irradiation energy and irradiation time-dependent deprotection allows gradually controlled charge regulation in mesopores. This approach of in-situ functionalization using multistimuli-responsive PEO-b-PNBA block copolymers facilitates the fabrication of multi-responsive hybrid mesoporous silica films and bears high potential for the production of complex, hierarchical, multifunctional mesoporous materials. This fabrication method including direct functionalization of mesoporous structures is of high interest for many applications based on controlled molecular transport in nanoscale pores, such as sensing, separation, or catalysis

Simultaneous Nanolocal Polymer and In Situ Readout Unit Placement in Mesoporous Separation Layers

Bioinspired solid-state nanopores and nanochannels have attracted interest in the last two decades, as they are envisioned to advance future sensing, energy conversion, and separation concepts. Although much effort has been made regarding functionalization of these materials, multifunctionality and accurate positioning of functionalities with nanoscale precision still remain challenging. However, this precision is necessary to meet transport performance and complexity of natural pores in living systems, which are often based on nonequilibrium states and compartmentalization. In this work, a nanolocal functionalization and simultaneous localized sensing strategy inside a filtering mesoporous film using precisely placed plasmonic metal nanoparticles inside mesoporous films with pore accessibility control is demonstrated. A single layer of gold nanoparticles is incorporated into mesoporous thin films with precise spatial control along the nanoscale layer thickness. The local surface plasmon resonance is applied to induce a photopolymerization leading to a nanoscopic polymer shell around the particles and thus nanolocal polymer placement inside the mesoporous material. As near-field modes are sensitive to the dielectric properties of their surrounding, the in situ sensing capability is demonstrated using UV–vis spectroscopy. It is demonstrated that the sensing sensitivity only slightly decreases upon functionalization. The presented nanolocal placement of responsive functional polymers into nanopores offers a simultaneous filtering and nanoscopic readout function. Such a nanoscale local control is envisioned to have a strong impact onto the development of new transport and sensor concepts, especially as the system can be developed into higher complexity using different metal nanoparticles and additional design of mesoporous film filtering properties

Simultaneous Nanolocal Polymer and In Situ Readout Unit Placement in Mesoporous Separation Layers: Public Data

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PEO-b-PNBA in-situ functionalized mesoporous silica films and their light- and pH-controlled ionic mesopore accessibility

Multistimuli-responsive, in-situ functionalized mesoporous silica films were fabricated by evaporation-induced self-assembly through physical entrapment of the functional template poly(ethylene oxide)-b-poly(2-nitrobenzyl acrylate) (PEO-b-PNBA). The light-cleavable and pH-responsive block copolymer PEO-b-PNBA simultaneously serves as structure-directing agent and for in-situ polymer functionalization of the generated mesopore space. The use of different PEO-b-PNBA compositions results in highly filled hybrid mesoporous silica films with different pore sizes, porosity, and polymer chain sequence within the mesopores. Based on these structural variations and the polymer chain sequence the ionic permselectivity of the silica-polymer hybrid thin films is adjusted. The side chains of the template PNBA block can be deprotected upon irradiation, hereby releasing pH-responsive carboxylic acid groups. The irradiation energy and irradiation time-dependent deprotection allows gradually controlled charge regulation in mesopores. This approach of in-situ functionalization using multistimuli-responsive PEO-b-PNBA block copolymers facilitates the fabrication of multi-responsive hybrid mesoporous silica films and bears high potential for the production of complex, hierarchical, multifunctional mesoporous materials. This fabrication method including direct functionalization of mesoporous structures is of high interest for many applications based on controlled molecular transport in nanoscale pores, such as sensing, separation, or catalysis

Self-Decorating Cells Via Surface-Initiated Enzymatic Controlled Radical Polymerizations

Innovatively utilizing surface-displayed horseradish peroxidase, this paper explores the enzymatic catalysis of both bioRAFT polymerization and bioATRP to prompt polymer synthesis on the surface of Saccharomyces cerevisiae cells, with bioATRP outperforming bioRAFT polymerization. The resulting surface modification of living yeast cells with synthetic polymers allows for a significant alternation of yeast phenotype, including growth profile, aggregation characteristics, and conjugation of non-native enzymes to the clickable polymers on the cell surface, opening new avenues in bioorthogonal cell-surface engineering

Coordination Polymer to Atomically Thin, Holey, Metal‐Oxide Nanosheets for Tuning Band Alignment

Altres ajuts: ICN2 is supported by the CERCA Programme/Generalitat de Catalunya.Holey 2D metal oxides have shown great promise as functional materials for energy storage and catalysts. Despite impressive performance, their processing is challenged by the requirement of templates plus capping agents or high temperatures; these materials also exhibit excessive thicknesses and low yields. The present work reports a metal-based coordination polymer (MCP) strategy to synthesize polycrystalline, holey, metal oxide (MO) nanosheets with thicknesses as low as two-unit cells. The process involves rapid exfoliation of bulk-layered, MCPs (Ce-, Ti-, Zr-based) into atomically thin MCPs at room temperature, followed by transformation into holey 2D MOs upon the removal of organic linkers in aqueous solution. Further, this work represents an extra step for decorating the holey nanosheets using precursors of transition metals to engineer their band alignments, establishing a route to optimize their photocatalysis. The work introduces a simple, high-yield, room-temperature, and template-free approach to synthesize ultrathin holey nanosheets with high-level functionalities