14 research outputs found
Inorganic Chiral Nanomaterials: Design Strategies and Their Properties
Interest in the synthesis of chiral nanostructures has been fueled by their prime fundamental and potential application of chiral nanostructures in biosensing, telecommunication, display technologies, diffraction-free patterning, and chiral catalysis. Although chirality is often associated with biochemistry due to numerous chiral biomolecules, today chiral inorganic nanostructures have attracted much attention, but their optical properties remain largely unexplored. Nanoscale inorganic chiral materials strongly rotate linear and circularly polarized light passing through them. Such optical effects are relatively easy to observe and are being actively investigated as a part of the study of chiral photonics and plasmonics. However, the opposite effects, the transfer of spin angular momenta of circularly polarized photons to materials and their subsequent nanoscale restructuring, are much less understood.
In chapters II and III of this dissertation, I describe an experiment that demonstrates how circularly polarized light (CPL) affects dispersions of racemic nanoparticles (NPs). The intrinsic, non-covalent electrostatic, dipole-dipole, and van der Walls interactions, as well as hydrogen bonds between NPs combined to produce different types of NP superstructures. The transition from individual NPs to their superstructure assemblies can be easily controlled, visualized, and studied by different means. This strategy was applicable to various materials such as gold. By illuminating a seed-free gold ion dispersion with CPL, I could obtain optically active gold nanostructures.
In chapter IV, I describe how I synthesized chiral cobalt oxide NPs using chiral molecules, namely, L- and D-cysteine as surface ligands. The chiral paramagnetic NPs showed ~ 10 times greater optical activity than other metal or semiconducting NPs of similar size. Moreover, the optical activities of the latter were mainly in the UV region while our NPs show practical activity in both the UV and visible ranges. The results of this study provide new opportunities for the design and synthesis of novel materials and contribute to a better understanding of materials at the nexus of magnetism and chirality.PHDMacromolecular Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/140792/1/jyeom_1.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 Ăą 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 âCoherent Effects in Hybrid
Nanostructures for Lineshape Engineering of Electromagnetic Mediaâ (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
Branched Aramid Nanofibers
Interconnectivity of components in threeâdimensional networks (3DNs) is essential for stress transfer in hydrogels, aerogels, and composites. Entanglement of nanoscale components in the network relies on weak shortârange intermolecular interactions. The intrinsic stiffness and rodâlike geometry of nanoscale components limit the cohesive energy of the physical crosslinks in 3DN materials. Nature realizes networked gels differently using components with extensive branching. Branched aramid nanofibers (BANFs) mimicking polymeric components of biological gels were synthesized to produce 3DNs with high efficiency stress transfer. Individual BANFs are flexible, with the number of branches controlled by base strength in the hydrolysis process. The extensive connectivity of the BANFs allows them to form hydroâ and aerogel monoliths with an order of magnitude less solid content than rodâlike nanocomponents. Branching of nanofibers also leads to improved mechanics of gels and nanocomposites.3DâGerĂŒste mit effizienter SpannungsĂŒbertragung können mithilfe von verzweigten AramidâNanofasern (BANFs) hergestellt werden. Die starke VerknĂŒpfung der BANFs fĂŒhrt zu Hydrogelâ und AerogelâMonolithen mit viel geringerem Feststoffgehalt als bei Verwendung stabförmiger Nanokomponenten. Die Verzweigung verbessert zudem die Gelmechanik, sodass kontinuierliche lumineszierende Mikrofasern und hochleistungsfĂ€hige Nanokomposite erhalten werden können.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138299/1/ange201703766-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138299/2/ange201703766_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138299/3/ange201703766.pd
Branched Aramid Nanofibers
Interconnectivity of components in threeâdimensional networks (3DNs) is essential for stress transfer in hydrogels, aerogels, and composites. Entanglement of nanoscale components in the network relies on weak shortârange intermolecular interactions. The intrinsic stiffness and rodâlike geometry of nanoscale components limit the cohesive energy of the physical crosslinks in 3DN materials. Nature realizes networked gels differently using components with extensive branching. Branched aramid nanofibers (BANFs) mimicking polymeric components of biological gels were synthesized to produce 3DNs with high efficiency stress transfer. Individual BANFs are flexible, with the number of branches controlled by base strength in the hydrolysis process. The extensive connectivity of the BANFs allows them to form hydroâ and aerogel monoliths with an order of magnitude less solid content than rodâlike nanocomponents. Branching of nanofibers also leads to improved mechanics of gels and nanocomposites.Branching needed: The production of 3D networks with efficient stress transfer is enabled by branched aramid nanofibers (BANFs). The extensive connectivity of the BANFs leads to the formation of hydroâ and aerogel monoliths with much less solid content than rodâlike nanocomponents. The branching also leads to improved gel mechanics, allowing the preparation of continuous microscale luminescent fibers and highâperformance nanocomposites.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138347/1/anie201703766.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138347/2/anie201703766-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138347/3/anie201703766_am.pd
Chiral Biomaterials for Nanomedicines: From Molecules to Supraparticles
Chirality, the property whereby an object or a system cannot be superimposed on its mirror image, prevails amongst nature over various scales. Especially in biology, numerous chiral building blocks and chiral-specific interactions are involved in many essential biological activities. Despite the prevalence of chirality in nature, it has been no longer than 70 years since the mechanisms of chiral-specific interactions drew scientific attention and began to be studied. Owing to the advent of chiral-sensitive equipment such as circular dichroism spectrometers or chiral liquid columns for chromatography, it has recently been possible to achieve a deeper understanding of the chiral-specific interactions and consequential impacts on the functionality and efficiency of nanomedicine. From this point of view, it is worthwhile to examine previously reported chiral biomaterials with their compositions and possible applications to achieve new paradigms of biomaterials. This review discusses chiral materials on various scales and their biological applications
Universal Synthesis of Single-Phase Pyrite FeS<sub>2</sub> Nanoparticles, Nanowires, and Nanosheets
Nanoscale pyrite FeS<sub>2</sub> is considered to be
one of few
potentially transformative materials for photovoltaics capable of
bridging the cost/performance gap of solar batteries. It also holds
promise for energy storage applications as the material for high-performance
cathodes. Despite prospects, the synthesis of FeS<sub>2</sub> nanostructures
and diversity of their geometries has been hardly studied. Moreover,
the state-of-the-art aqueous dispersions of nanoscale pyrite, which
have special significance for solar energetics, are particularly disappointing
due to low quality. There are no known methods to produce well-crystallized
nanoparticles and other geometries of nanoscale pyrite in water or
mixed aqueous solvents. Here, we describe a successful synthesis of
single-phase pyrite nanoparticles with a diameter of 2â5 nm
in polar solvent and aqueous dispersions. The particles display high
uniformity and crystallographic purity. Moreover, the synthetic approach
developed for nanoparticles was proven to be quite universal and can
be modified to produce both nanowires and nanosheets, which also display
high crystallinity. The diameter of the pyrite nanowires was 80â120
nm with the length exceeding 5 ÎŒm. The nanosheets displayed
lateral dimensions of 100â200 nm with the thickness of 2 nm.
Availability of single-phase FeS<sub>2</sub> nanoscale aqueous dispersions
is expected to stimulate further studies of these materials in green
energy conversion technologies and drug delivery applications
Chiral Supraparticles for Controllable Nanomedicine
Chirality is ubiquitous in nature and hard-wired into every biological system. Despite the prevalence of chirality in biological systems, controlling biomaterial chirality to influence interactions with cells has only recently been explored. Chiral-engineered supraparticles (SPs) that interact differentially with cells and proteins depending on their handedness are presented. SPs coordinated with d-chirality demonstrate greater than threefold enhanced cell membrane penetration in breast, cervical, and multiple myeloma cancer cells. Quartz crystal microbalance with dissipation and isothermal titration calorimetry measurements reveal the mechanism of these chiral-specific interactions. Thermodynamically, d-SPs show more stable adhesion to lipid layers composed of phospholipids and cholesterol compared to l-SPs. In vivo, d-SPs exhibit superior stability and longer biological half-lives likely due to opposite chirality and thus protection from endogenous proteins including proteases. This work shows that incorporating d-chirality into nanosystems enhances uptake by cancer cells and prolonged in vivo stability in circulation, providing support for the importance of chirality in biomaterials. Thus, chiral nanosystems may have the potential to provide a new level of control for drug delivery systems, tumor detection markers, biosensors, and other biomaterial-based devices
Recent advances in chiral nanomaterials with unique electric and magnetic properties
Abstract
Research on chiral nanomaterials (NMs) has grown radically with a rapid increase in the number of publications over the past decade. It has attracted a large number of scientists in various fields predominantly because of the emergence of unprecedented electric, optical, and magnetic properties when chirality arises in NMs. For applications, it is particularly informative and fascinating to investigate how chiral NMs interact with electromagnetic waves and magnetic fields, depending on their intrinsic composition properties, atomic distortions, and assembled structures. This review provides an overview of recent advances in chiral NMs, such as semiconducting, metallic, and magnetic nanostructures.http://deepblue.lib.umich.edu/bitstream/2027.42/173999/1/40580_2022_Article_322.pd