Layered biomimetic and kirigami nanocomposites

Finding materials with combinations of several extreme properties is one of the key requirements for the successful engineering of adaptive systems. Successful realization of such materials requires new choices for nanoscale components and new manufacturing approaches. Layer-by-layer assembly (LBL) is one of such technique that affords engineering of nanocomposite materials based on sequential adsorption of nanometer scale layers of polymers and inorganic particle, nanowires, nanotubes, sheets, etc. Importantly, it can lead to the materials with seemingly “impossible” combinations of physical properties encompassing mechanical, electrical, optical, and biological characteristics and distinct pathways to scalability. Hard-to-reach combinations of electrical and mechanical properties necessary for a number of technologies will be discussed. Composites with high stiffness properties + high damping and as well as high stiffness + transparency will be demonstrated. Energy and biomedical applications are particularly demanding on materials used. A new type of nanoscale “building blocks’ such as aramid nanofibers (ANFs) can also be incorporated in such composites with potential applications as ion conductors for lithium ion batteries. It was demonstrated that LBL assembled nanocomposites enable lithium battery anodes with ultrahigh discharge rates. Incorporation of aramid nanofibers also affords combining high toughness and ion conductivity essential for battery separators. ANF-based Li ion conducting separators are capable of suppressing lithium and copper dendrites with nanometer scale overall thickness. The last part of the talk will describe our latest exploits in the area of composites to achieve the combination of high conductivity and high stretchability. The studies that will be highlighted include composites enabling self-organization processes during deformation and kirigami materials that display unusually constant conductance over a wide range of strains

Self-Assembly of Asymmetrically Functionalized Titania Nanoparticles into Nanoshells

Titania (anatase) nanoparticles were anisotropically functionalized in water-toluene Pickering emulsions to self-assemble into nanoshells with diameters from 500 nm to 3 mu m as candidates for encapsulation of drugs and other compounds. The water-phase contained a hydrophilic ligand, glucose-6-phosphate, while the toluene-phase contained a hydrophobic ligand, n-dodecylphosphonic acid. The addition of a dilute sodium alginate suspension that provided electrostatic charge was essential for the self-limited assembly of the nanoshells. The self-assembled spheres were characterized by scanning electron microscopy, elemental mapping, and atomic force microscopy. Drug release studies using tetracycline suggest a rapid release dominated by surface desorption

Water‐Rich Biomimetic Composites with Abiotic Self‐Organizing Nanofiber Network

Load‐bearing soft tissues, e.g., cartilage, ligaments, and blood vessels, are made predominantly from water (65–90%) which is essential for nutrient transport to cells. Yet, they display amazing stiffness, toughness, strength, and deformability attributed to the reconfigurable 3D network from stiff collagen nanofibers and flexible proteoglycans. Existing hydrogels and composites partially achieve some of the mechanical properties of natural soft tissues, but at the expense of water content. Concurrently, water‐rich biomedical polymers are elastic but weak. Here, biomimetic composites from aramid nanofibers interlaced with poly(vinyl alcohol), with water contents of as high as 70–92%, are reported. With tensile moduli of ≈9.1 MPa, ultimate tensile strains of ≈325%, compressive strengths of ≈26 MPa, and fracture toughness of as high as ≈9200 J m−2, their mechanical properties match or exceed those of prototype tissues, e.g., cartilage. Furthermore, with reconfigurable, noncovalent interactions at nanomaterial interfaces, the composite nanofiber network can adapt itself under stress, enabling abiotic soft tissue with multiscale self‐organization for effective load bearing and energy dissipation.Water‐rich biomimetic composites from aramid nanofibers interlaced with poly(vinyl alcohol) emulate the collagen–proteoglycan network in load‐bearing soft tissues. The hydrogen bonding between stiff nanofibers and soft polymers affords synergistic stiffening and toughening, allowing the nanofiber network to self‐organize under stress for effective load bearing and energy dissipation. Their mechanics, biocompatibility, and high water content permit utilization as load‐bearing biomaterials and for other applications including durable high‐transport‐rate membranes, membranes in water desalination, fuel cells, and batteries.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141174/1/adma201703343-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141174/2/adma201703343_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141174/3/adma201703343.pd

Materials science: Carbon sheet solutions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62936/1/442254a.pd

Chiral templating of self-assembling nanostructures by circularly polarized light

PMCID: PMC4387888.-- et al.The high optical and chemical activity of nanoparticles (NPs) signifies the possibility of converting the spin angular momenta of photons into structural changes in matter. Here, we demonstrate that illumination of dispersions of racemic CdTe NPs with right- (left-)handed circularly polarized light (CPL) induces the formation of right- (left-)handed twisted nanoribbons with an enantiomeric excess exceeding 30%, which is â 1/410 times higher than that of typical CPL-induced reactions. Linearly polarized light or dark conditions led instead to straight nanoribbons. CPL templating of NP assemblies is based on the enantio-selective photoactivation of chiral NPs and clusters, followed by their photooxidation and self-assembly into nanoribbons with specific helicity as a result of chirality-sensitive interactions between the NPs. The ability of NPs to retain the polarization information of incident photons should open pathways for the synthesis of chiral photonic materials and allow a better understanding of the origins of biomolecular homochirality.This material is based on work partially supported by the Center for Solar and Thermal Energy Conversion, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under award number #DE-SC0000957, and by ARO MURI W911NF-12-1-0407 ‘Coherent Effects in Hybrid Nanostructures for Lineshape Engineering of Electromagnetic Media’ (N.A.K. and S.L.). We acknowledge support from the NSF under grant ECS-0601345; CBET 0933384; CBET 0932823; and CBET 1036672. Financial support from the Robert A. Welch Foundation (C-1664) is also acknowledged (S.L.). Support from the NIH grant GM085043 (P.Z.) is gratefully acknowledged. The work of P.K. was supported by the NSF DMR grant No. 1309765 and by the ACS PRF grant No. 53062-ND6.Peer Reviewe

Synthesis and bioevaluation of 125 I-labeled gold nanorods

A novel technique is described for monitoring the in vivo behavior of gold nanorods (GNRs) using _-imaging. GNRs were radiolabeled using [ 125 I] sodium iodide in a simple and fast manner with high yield and without disturbing their optical properties. Radiolabeled GNRs were successfully visualized by radioisotope tagging, allowing longitudinal in vivo studies to be performed repeatedly in the same animal. The preliminary biodistribution study showed that PEGylated GNRs have much longer blood circulation times and clear out faster, while bare GNRs accumulate quickly in the liver after systematic administration. The highly efficient method reported here provides an extensively useful tool for guidance of the design and development of new gold nanoparticles as target-specific agents for both diagnostics and photothermal therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90787/1/0957-4484_22_13_135102.pd

Diverse Nanoassemblies of Graphene Quantum Dots and Their Mineralogical Counterparts

Complex structures from nanoparticles are found in rocks, soils, and sea sediments but the mechanisms of their formation are poorly understood, which causes controversial conclusions about their genesis. Here we show that graphene quantum dots (GQDs) can assemble into complex structures driven by coordination interactions with metal ions commonly present in environment and serve a special role in Earth’s history, such as Fe3+ and Al3+. GQDs self- assemble into mesoscale chains, sheets, supraparticles, nanoshells, and nanostars. Specific assembly patterns are determined by the effective symmetry of the GQDs when forming the coordination assemblies with the metal ions. As such, maximization of the electronic delocalization of Ï - orbitals of GQDs with Fe3+ leads to GQD- Fe- GQD units with D2 symmetry, dipolar bonding potential, and linear assemblies. Taking advantage of high electron microscopy contrast of carbonaceous nanostructures in respect to ceramic background, the mineralogical counterparts of GQD assemblies are found in mineraloid shungite. These findings provide insight into nanoparticle dynamics during the rock formation that can lead to mineralized structures of unexpectedly high complexity.Complex structures from nanoparticles are found in rocks, soils, and sea sediments but the mechanisms of their formation are poorly understood. It is shown that graphene quantum dots (GQDs) can assemble into complex structures driven by coordination interactions with metal ions commonly present in the environment and play a special role in Earth’s history, such as Fe3+ and Al3+.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155475/1/anie201908216_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155475/2/anie201908216.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155475/3/anie201908216-sup-0001-misc_information.pd

Self‐Assembly Mechanism of Spiky Magnetoplasmonic Supraparticles

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106774/1/adfm201302405.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106774/2/adfm201302405-sup-0001-S1.pd

Diverse Nanoassemblies of Graphene Quantum Dots and Their Mineralogical Counterparts

Complex structures from nanoparticles are found in rocks, soils, and sea sediments but the mechanisms of their formation are poorly understood, which causes controversial conclusions about their genesis. Here we show that graphene quantum dots (GQDs) can assemble into complex structures driven by coordination interactions with metal ions commonly present in environment and serve a special role in Earth’s history, such as Fe3+ and Al3+. GQDs self- assemble into mesoscale chains, sheets, supraparticles, nanoshells, and nanostars. Specific assembly patterns are determined by the effective symmetry of the GQDs when forming the coordination assemblies with the metal ions. As such, maximization of the electronic delocalization of Ï - orbitals of GQDs with Fe3+ leads to GQD- Fe- GQD units with D2 symmetry, dipolar bonding potential, and linear assemblies. Taking advantage of high electron microscopy contrast of carbonaceous nanostructures in respect to ceramic background, the mineralogical counterparts of GQD assemblies are found in mineraloid shungite. These findings provide insight into nanoparticle dynamics during the rock formation that can lead to mineralized structures of unexpectedly high complexity.Komplexe Strukturen aus Nanopartikeln sind in Gesteinen, Böden und Meeressedimenten zu finden, aber die Mechanismen ihrer Entstehung sind kaum verstanden. Es wird gezeigt, dass sich Graphenquantenpunkte (GQDs) zu komplexen Strukturen zusammenfügen können, angetrieben durch Koordinationswechselwirkungen mit Metallionen wie Fe3+ and Al3+, die in der Umwelt häufig vorkommen und eine besondere Rolle in der Erdgeschichte spielen.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155470/1/ange201908216.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155470/2/ange201908216_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155470/3/ange201908216-sup-0001-misc_information.pd