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Chiral nanomaterials provide a rich platform for versatile applications. Tuning the wavelength of polarization rotation maxima in the broad range including short-wave infrared (SWIR) is a promising candidate for infrared neural stimulation, imaging, and nanothermometry. However, the majority of previously developed chiral nanomaterials reveal the optical activity in a relatively shorter wavelength range (ultraviolet-visible, UV-vis), not in SWIR. Here, we demonstrate a versatile method to synthesize chiral copper sulfides using cysteine, as the stabilizer, and transferring the chirality from molecular- to the microscale through self-assembly. The assembled structures show broad chiroptical activity in the UV-vis-NIR-SWIR region (200-2500 nm). Importantly, we can tune the chiroptical activity by simply changing the reaction conditions. This approach can be extended to materials platforms for developing next-generation optical devices, metamaterials, telecommunications, and asymmetric catalysts.

Biological systems consist of hierarchical protein structures, each of which has unique 3D geometries optimized for specific functions. In the past decades, the growth of inorganic materials on specific proteins has attracted considerable attention. However, the use of specific proteins as templates has only been demonstrated in relatively simple organisms, such as viruses, limiting the range of structures that can be used as scaffolds. This study proposes a method for synthesizing metallic structures that resemble the 3D assemblies of specific proteins in mammalian cells and animal tissues. Using 1.4 nm nanogold-conjugated antibodies, specific proteins within cells and ex vivo tissues are labeled, and then the nanogold acts as nucleation sites for growth of metal particles. As proof of concept, various metal particles are grown using microtubules in cells as templates. The metal-containing cells are applied as catalysts and show catalytic stability in liquid-phase reactions due to the rigid support provided by the microtubules. Finally, this method is used to produce metal structures that replicate the specific protein assemblies of neurons in the mouse brain or the extracellular matrices in the mouse kidney and heart. This new biotemplating approach can facilitate the conversion of specific protein structures into metallic forms in ex vivo multicellular organisms.

Boosting chiral nanoparticle responses Optical nanomaterials that combine chirality and magnetism are useful for magneto-optics and as chiral catalysts. Although chiral inorganic nanostructures can exhibit high circular dichroism, modulating this optical activity has usually required irreversible chemical changes. Yeom et al. synthesized paramagnetic cobalt oxide (Co 3 O 4 ) nanoparticles with l - and d -cysteine surface ligands. These ligands created chiral distortions of the crystal lattices, and this anisotropy led to much stronger chiroptical activity. The circular dichroism in the ultraviolet of nanoparticle gels could be modulated with magnetic fields of ∼1.5 tesla. Science , this issue p. 309

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. Here, we present chiral-engineered supraparticles (SPs) that interact differentially with cells and proteins depending on their handedness. SPs coordinated with D- chirality demonstrated greater than three-fold enhanced cell membrane penetration in breast, cervical, and multiple myeloma cancer cells. We carried out quartz crystal microbalance with dissipation and isothermal titration calorimetry measurements to understand the mechanism of these chiral-specific interactions. Thermodynamically, D-SPs showed more stable adhesion to lipid layers composed of phospholipids and cholesterol compared to L-SPs. In vivo, D-SPs exhibited superior stability and longer biological half-lives likely due to opposite chirality and thus protection from endogenous proteins including proteases. This work showed that incorporating D-chirality into nanosystems enhanced 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.

Matured syntheses of inorganic nanocolloids today have allowed production of diverse asymmertic nanoparticles (NP) and even more complex assemblies, introducing a variety of nanomaterials with unique properties. Chirality is one of most intriguing symmetry groups in field of material science due to the optical rotatory power of chiral substances. Strong optical activity of inorganic nanoparticles (NPs) afford photosynthetic routes to chiral superstructures using circularly polarized photons (1). Although plasmonic NPs are promising candidates for such synthetic routes due to the strong rotatory power of highly delocalized plasmonic states (2), realization of light- driven synthesis of chiral nanostructures has been more challenging for plasmonic NPs than for the semiconductor due to the short lifetime of the plasmonic states. The process also can be difficult to recognize, and therefore requires unconventional approaches for the quantification of chiral products. Here, we demonstrate that illumination of Au precursors in the presence of citric acid with right- (left-) handed circularly polarized light (CPL) induces the formation of chiral Au nanostructures. Despite seemingly irregular shape of the particles, the resulted colloids showed distinctive mirror-imaged opposite circular dichroism (CD) bands according to the handedness of illuminated CPL. Circular dichroic response and geometric chirality from these seemingly achiral structures were successfully demonstrated and quantified by implementing three-dimensional (3D) electron tomography (e-tomo) into computational model. The mechanism of the light-driven assembly of chiral nanostructures is based on the asymmetric displacement of NPs in dynamic assemblies by plasmonic fields fol-lowed by particle-to-particle attachment. The ability of Au nanostructures to retain the polarization information of incident photons can be applicable to light absorbing materials, thus to create a variety of chiral nanomaterials. Similar examination of seemingly irregular NP through suggested chirality measure can also elucidate previously puzzling optical response from unclear geometric asymmetry of nanomaterials.

Photon-to-matter chirality transfer offers both simplicity and universality to chiral synthesis, but its efficiency is typically low for organic compounds. Besides the fundamental importance of this process relevant for understanding the origin of homochirality on Earth, new pathways for imposing chiral bias during chemical process are essential for a variety of technologies from medicine to informatics. The strong optical activity of inorganic nanoparticles (NPs) affords photosynthetic routes to chiral superstructures using circularly polarized photons. Although plasmonic NPs are promising candidates for such synthetic routes due to the strong rotatory power of highly delocalized plasmonic states (Ma et al. Chem. Rev.2017, 117 (12), 8041), realization of light-driven synthesis of chiral nanostructures has been more challenging for plasmonic NPs than for the semiconductor due to the short lifetime of the plasmonic states. Here we show that illumination of gold salt solutions with circularly polarized light induces the formation of NPs and their subsequent assembly into chiral nanostructures 10–15 nm in diameter. Despite their seemingly irregular shape, the resulting nanocolloids showed circular dichroism (CD) spectra with opposite polarity after exposure to photons with left and right circular polarization. The sign and spectral position of the CD peaks of illuminated dispersions matched those calculated for nanostructures with complex geometry identified from electron tomography images. Quantification of the complex shapes of NP assemblies using chirality measures revealed a direct correlation with the experimental spectra. The light-driven assembly of chiral nanostructures originates from the asymmetric displacement of NPs in dynamic assemblies by plasmonic fields followed by particle-to-particle attachment. The ability of gold NPs to “lock” the chirality of the incident photons in assembled nanostructures can be used to create a variety of chiral nanomaterials with plasmonic resonances.

Accurate medical recordkeeping is a major challenge in many low-resource settings where well-maintained centralized databases do not exist, contributing to 1.5 million vaccine-preventable deaths annually. Here, we present an approach to encode medical history on a patient using the spatial distribution of biocompatible, near-infrared quantum dots (NIR QDs) in the dermis. QDs are invisible to the naked eye yet detectable when exposed to near infrared light. QDs with a copper indium selenide core and aluminum-doped zinc sulfide shell were tuned to emit in the NIR spectrum by controlling stoichiometry and shelling time. The formulation showing the greatest resistance to photobleaching after simulated sunlight exposure (5-year equivalence) through pigmented human skin was encapsulated in microparticles for use in vivo. In parallel, microneedle geometry was optimized in silico and validated ex vivo using porcine and synthetic human skin. QD-containing microparticles were then embedded in dissolvable microneedles and administered to rats with or without a vaccine. Longitudinal in vivo imaging using a smartphone adapted to detect in the NIR demonstrated that microneedle-delivered QD patterns remained bright and could be accurately identified using a machine learning algorithm nine months after application. Additionally, co-delivery with inactivated poliovirus vaccine produced neutralizing antibody titers above the threshold considered protective. These findings suggest that intradermal QDs can be used to reliably encode information and can be delivered with a vaccine, which may be particularly valuable in the developing world and opens up new avenues for decentralized data storage and biosensing.

Interconnectivity of components in three-dimensional networks (3DNs) is essential for stress transfer in hydrogels, aerogels, and composites. Entanglement of nanoscale components in the network relies on weak short-range intermolecular interactions. The intrinsic stiffness and rod-like 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 hydro- and aerogel monoliths with an order of magnitude less solid content than rod-like nanocomponents. Branching of nanofibers also leads to improved mechanics of gels and nanocomposites.

The resistance of bioceramics against non-specific adsorption of serum proteins is critical for a wide range of biomedical applications. Some polysaccharides serve as natural protein-resistant molecules in extracellular matrices; however, the stable adhesion of polysaccharides to ceramic biomaterials in an aqueous solution is very challenging because chemical linkages at organic/inorganic interfaces are susceptible to hydrolytic degradation. Here, a catechol-grafted dextran, which strongly binds to titania (TiO2 ) in an aqueous milieu to effectively suppress cell adhesion through anti-fouling activity against non-specific protein adsorption, is introduced. Catechol is conjugated approximately to 6.7 mol% of glucose units of dextran via a carbamate ester linkage, corresponding to roughly three catechols per dextran chain having an average molecular weight of 6 kDa. Multivalent interactions of catechols with a titanium atom, enabled by the graft-type structure, provide a very stable coating of dextran on this inorganic surface. The adhesion of HeLa cells on the dextran-coated titania surface is reduced by 2.4-fold compared to that on a pristine titania surface. These results suggest that the graft-type incorporation of a small number of catechol moieties along a dextran backbone is an effective means of producing a stable anti-fouling interface on inorganic biomaterials in an aqueous environment.

Nanoscale pyrite FeS2 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 FeS2 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 2–5 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 ...

Surface modification is one of the most important techniques in modern science and engineering. The facile introduction of a wide variety of desired properties onto virtually any material surface is an ultimate goal in surface chemistry. To achieve this goal, the incorporation of structurally diverse molecules onto any material surface is an essential capability for ideal surface modification. Here, a general strategy for surface modification is presented in which many diverse surfaces can be functionalized by immobilizing a wide variety of molecules. This strategy functionalizes surfaces by a one-step immersion of substrates in a one-pot mixture of a molecule and a catecholamine surface modification agent. This one-step procedure for surface modification represents a standard protocol to control interfacial properties., Armed Forces Institute of Regenerative Medicine (Award W81XWH-08-2-0034), National Institutes of Health (U.S.) (2R01DE016516-06)

All-trans-retinoic acids (ATRA) are ionically complexed with cationic polyelectrolytes containing tertiary amines and self-assembled into nanoscale colloidal structures. Poly(2-(dimethylamino)ethyl methacrylate) grafted with polyethylene glycol, poly(DMAEMA-g-PEG), is used as a double hydrophilic, cationic polyelectrolyte. The polyion/ATRA complexes are formed by adding ATRA in dimethyl sulfoxide into aqueous solution of poly(DMAEMA-g-PEG). This complexation effectively suppresses the formation of undesirable drug crystallites and produces stable colloidal nanostructures having a hydrodynamic diameter of about 15 nm at a neutral pH. However, as the pH decreases below about 6, they undergo dramatic structural change into large aggregates of about 250 nm in diameter presumably due to the dissociation of ATRA from the polyelectrolyte. We expect that this pH-sensitive response of the polyion/ATRA complexes is useful for intracellular translocation at a neutral pH followed by the endosomal escape of ATRA in an acidic condition.

The resistance of bioceramics against non-specific adsorption of serum proteins is critical for a wide range of biomedical applications. Some polysaccharides serve as natural protein-resistant molecules in extracellular matrices; however, the stable adhesion of polysaccharides to ceramic biomaterials in an aqueous solution is very challenging because chemical linkages at organic/inorganic interfaces are susceptible to hydrolytic degradation. Here, a catechol-grafted dextran, which strongly binds to titania (TiO2 ) in an aqueous milieu to effectively suppress cell adhesion through anti-fouling activity against non-specific protein adsorption, is introduced. Catechol is conjugated approximately to 6.7 mol% of glucose units of dextran via a carbamate ester linkage, corresponding to roughly three catechols per dextran chain having an average molecular weight of 6 kDa. Multivalent interactions of catechols with a titanium atom, enabled by the graft-type structure, provide a very stable coating of dextran on this inorganic surface. The adhesion of HeLa cells on the dextran-coated titania surface is reduced by 2.4-fold compared to that on a pristine titania surface. These results suggest that the graft-type incorporation of a small number of catechol moieties along a dextran backbone is an effective means of producing a stable anti-fouling interface on inorganic biomaterials in an aqueous environment.

However, functionalizing surfaces in a material-independent manner was not demonstrated, and the oxidation chemistry of the polyphenols was not investi-gated at a molecular level due to the well-known complexity of crosslinking chemistry. Herein, we report that a plant-inspired, amine-containing small molecule called 5-pyrogallol 2-aminoethane (PAE) can perform surface functionalization in a material-independent manner. The presence of primary amine and pyrogallol moie-ties are essential for the material-independent coating ability of PAE compared to other compounds with the pyrogallol group. The PAE-functionalized surfaces are multifunctional in that they are able to trigger ring-opening polymerization, form a gold nanoshell adsorbing near infrared spectrum, and maintain long-lasting hydrophilicity on poly(dimethylsiloxane) (PDMS) surfaces. The multi-functionality of the PAE-mediated surface chemistry will be useful in many areas, such as medical device development, drug delivery, mammalian cell culture, and the development of energy storage devices.