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Twin pregnancies involving assisted reproductive technology, particularly among older women, are considered to be high risk and vulnerable to chemical exposures. Per- and polyfluoroalkyl substances (PFAS) can cross the placenta and affect the fetus, but their transplacental transfer (TPT) is not well characterized for twin pregnancies. We employed a subset of twin pregnancies from the Ideal Breast Milk (IBM) cohort and measured the levels of PFAS and related chemicals in maternal ( n = 78) and cord serum ( n = 156) samples. L-PFOS and PFOA were detected at higher levels in maternal serum, with geometric means of 4.22 and 2.80 ng/mL, respectively, while the level of Br-PFHxS was higher in cord serum (0.29 ng/mL). Higher maternal PFAS levels were associated with the occurrence of maternal vascular malperfusion. Greater differences in cord PFAS levels between twin newborns were associated with higher maternal PFAS levels and an asymmetrical placental perfusion. The TPT ratio exhibited a U-shaped pattern with the number of carbons of PFAS, similar to a singleton pregnancy. Moreover, those with eight carbon atoms, i.e., 9Cl-PF3ONS, PFOA, and PFOS, showed different TPT efficiencies with respect to their structure and functional group. While the twin pregnancy does not appear to influence exposure levels or TPT efficiencies of PFAS and related chemicals, the consequences of the exposure warrant further investigations in this population.

The colorimetric sensor-based electronic nose has been demonstrated to discriminate specific gaseous molecules for various applications, including health or environmental monitoring. However, conventional colorimetric sensor systems rely on RGB sensors, which cannot capture the complete spectral response of the system. This limitation can degrade the performance of machine learning analysis, leading to inaccurate identification of chemicals with similar functional groups. Here, we propose a novel time-resolved hyperspectral (TRH) data set from colorimetric array sensors consisting of 1D spatial, 1D spectral, and 1D temporal axes, which enables hierarchical analysis of multichannel 2D spectrograms via a convolution neural network (CNN). We assessed the outstanding classification performance of the TRH data set compared to an RGB data set by conducting a relative humidity (RH) concentration classification. The time-dependent spectral response of the colorimetric sensor was measured and trained as a CNN model using TRH and RGB sensor systems at different RH levels. While the TRH model shows a high classification accuracy of 97.5% for the RH concentration, the RGB model yields 72.5% under identical conditions. Furthermore, we demonstrated the detection of various functional volatile gases with the TRH system by using experimental and simulation approaches. The results reveal distinct spectral features from the TRH system, corresponding to changes in the concentration of each substance.

The surface-enhanced Raman scattering (SERS) technique has garnered significant interest due to its ultrahigh sensitivity, making it suitable for addressing the growing demand for disease diagnosis. In addition to its sensitivity and uniformity, an ideal SERS platform should possess characteristics such as simplicity in manufacturing and low analyte consumption, enabling practical applications in complex diagnoses including cancer. Furthermore, the integration of machine learning algorithms with SERS can enhance the practical usability of sensing devices by effectively classifying the subtle vibrational fingerprints produced by molecules such as those found in human blood. In this study, we demonstrate an approach for early detection of breast cancer using a bottom-up strategy to construct a flexible and simple three-dimensional (3D) plasmonic cluster SERS platform integrated with a deep learning algorithm. With these advantages of the 3D plasmonic cluster, we demonstrate that the 3D plasmonic cluster (3D-PC) exhibits a significantly enhanced Raman intensity through detection limit down to 10 -6 M (femtomole-(10 -17 mol)) for p -nitrophenol (PNP) molecules. Afterward, the plasma of cancer subjects and healthy subjects was used to fabricate the bioink to build 3D-PC structures. The collected SERS successfully classified into two clusters of cancer subjects and healthy subjects with high accuracy of up to 93%. These results highlight the potential of the 3D plasmonic cluster SERS platform for early breast cancer detection and open promising avenues for future research in this field.

Free-standing and film-type moisture-driven energy generators (MEGs) that harness the preferential interaction of ionized moisture with hydrophilic materials are interesting because of their wearability and portability without needing a water container. However, most such MEGs work in limited humidity conditions, which provide a substantial moisture gradient. Herein, we present a high-performance MEG with sustainable power-production capability in a wide range of environments. The bilayer-based device comprises a negatively surface-charged, hydrophilic MXene (Ti 3 C 2 T x ) aerogel and polyacrylamide (PAM) ionic hydrogel. The preferential selection on the MXene aerogel of positive charges supplied from the salts and water in the hydrogel is predicted by the first-principle simulation, which results in a high electric output in a wide relative humidity range from 20% to 95%. Furthermore, by replacing the hydrogel with an organohydrogel of PAM that has excellent water retention and structural stability, a device with long-term electricity generation is realized for more than 15 days in a broad temperature range (from -20 to 80 °C). Our MXene aerogel MEGs connected in series supply sufficient power for commercial electronic components in various outdoor environments. Moreover, an MXene aerogel MEG works as a self-powered sensor for recognizing finger bending and facial expression.

Adaptable and sensitive materials are essential for the development of advanced sensor systems such as bio and chemical sensors. Biomaterials can be used to develop multifunctional biosensor applications using genetic engineering. In particular, a plasmonic sensor system using a coupled film nanostructure with tunable gap sizes is a potential candidate in optical sensors because of its simple fabrication, stability, extensive tuning range, and sensitivity to small changes. Although this system has shown a good ability to eliminate humidity as an interferant, its performance in real-world environments is limited by low selectivity. To overcome these issues, we demonstrated the rapid response of gap plasmonic color sensors by utilizing metal nanostructures combined with genetically engineered M13 bacteriophages to detect volatile organic compounds (VOCs) and diagnose lung cancer from breath samples. The M13 bacteriophage was chosen as a recognition element because the structural protein capsid can readily be modified to target the desired analyte. Consequently, the VOCs from various functional groups were distinguished by using a multiarray biosensor based on a gap plasmonic color film observed by hierarchical cluster analysis. Furthermore, the lung cancer breath samples collected from 70 healthy participants and 50 lung cancer patients were successfully classified with a high rate of over 89% through supporting machine learning analysis.

Plasmonic nanoparticle clusters promise to support unique engineered electromagnetic responses at optical frequencies, realizing a new concept of devices for nanophotonic applications. However, the technological challenges associated with the fabrication of three-dimensional nanoparticle clusters with programmed compositions remain unresolved. Here, we present a novel strategy for realizing heterogeneous structures that enable efficient near-field coupling between the plasmonic modes of gold nanoparticles and various other nanomaterials via a simple three-dimensional coassembly process. Quantum dots embedded in the plasmonic structures display ∼56 meV of a blue shift in the emission spectrum. The decay enhancement factor increases as the total contribution of radiative and nonradiative plasmonic modes increases. Furthermore, we demonstrate an ultracompact diagnostic platform to detect M13 viruses and their mutations from femtoliter volume, sub-100 pM analytes. This platform could pave the way toward an effective diagnosis of diverse pathogens, which is in high demand for handling pandemic situations.

l-Ergothioneine (EGT) is a strong antioxidant used in industry, and it is commonly extracted from mushrooms; however, its production is limited. As an alternative, we developed metabolically engineered Corynebacterium glutamicum with reinforced sulfur assimilation and pentose phosphate pathways, which led to the accumulation of 45.0 and 63.2 mg/L EGT, respectively. Additionally, the overexpression of cysEKR resulted in further promoted EGT production in ET4 (66.5 mg/L) and ET7 (85.0 mg/L). Based on this result, we developed the strain ET11, in which all sulfur assimilatory, PP, and l-cysteine synthetic pathways were reinforced, and it synthesized 264.4 mg/L EGT. This study presents the first strategy for EGT synthesis that does not require precursor addition in C. glutamicum , and the production time was shortened. In addition, the synthesized EGT showed high radical scavenging activity (70.7%), thus confirming its antioxidant function. Consequently, this study showed the possibility of EGT commercialization by overcoming the limitations of industrial processes.

Direct photoluminescence (PL) from metal nanoparticles (NPs) without chemical dyes is promising for sensing and imaging applications since this offers a highly tunable platform for controlling and enhancing the signals in various conditions and does not suffer from photobleaching or photoblinking. It is, however, difficult to synthesize metal NPs with a high quantum yield (QY), particularly in the near-infrared (NIR) region where deep penetration and reduced light scattering are advantageous for bioimaging. Herein, we designed and synthesized Au-Ag long-body nanosnowman structures (LNSs), facilitated by polysorbate 20 (Tween 20). The DNA-engineered conductive junction between the head and body parts results in a charge transfer plasmon (CTP) mode in the NIR region. The junction morphology can be controlled by the DNA sequence on the Au core, and polythymine and polyadenine induced thick and thin junctions, respectively. We found that the LNSs with a thicker conductive junction generates the stronger CTP peak and PL signal than the LNSs with a thinner junction. The Au-Ag LNSs showed much higher intensities in both PL and QY than widely studied Au nanorods with similar localized surface plasmon resonance wavelengths, and notably, the LNSs displayed high photostability and robust, sustainable PL signals under continuous laser exposure for >15 h. Moreover, the PL emission from Au-Ag LNSs could be imaged in a deeper scattering medium than fluorescent silica NPs. Finally, highly robust PL-based cell images can be obtained using Au-Ag LNSs without significant signal change while repetitively imaging cells. The results offer the insights in plasmonic NIR probe design, and show that chemical dye-free LNSs can be a very promising candidate with a high QY and a robust, reliable NIR PL signal for NIR sensing and imaging applications.

Metabolic engineering of non-photosynthetic microorganisms to increase the utilization of CO 2 has been focused on as a green strategy to convert CO 2 into valuable products such as fatty acids. In this study, a CO 2 utilization pathway involving carbonic anhydrase and biotin carboxylase was formed to recycle CO 2 in the oleaginous yeast Yarrowia lipolytica , thereby increasing the production of fatty acids. In the recombinant strain in which the CO 2 utilization pathway was introduced, the production of fatty acids was 10.7 g/L, which was 1.5-fold higher than that of the wild-type strain. The resulting strain had a 1.4-fold increase in dry cell mass compared to the wild-type strain. In addition, linoleic acid was 47.7% in the fatty acid composition of the final strain, which was increased by 11.6% compared to the wild-type strain. These results can be applied as an essential technology for developing efficient and eco-friendly processes by directly utilizing CO 2 .

Plasmonic electrochromism, a change in the localized surface plasmon resonance (LSPR) with an applied electric potential, has been attracting increasing attention for the development of spectroscopic tools or optoelectronic systems. There is a consensus on the mechanism of plasmonic electrochromism based on the classical capacitor and the Drude model. However, the electrochromic behaviors of metallic nanoparticles in narrow optical windows have been demonstrated only with small monotonic LSPR shifts, which limits the use of the electrochromism. Here, we observed three distinct electrochromic behaviors of gold nanocubes with a wide potential range through in situ dark-field electrospectroscopy. Interestingly, the nanocubes show a faster frequency shift under the highly negative potential, and this opens the possibility of largely tunable electrochromic LSPR shifts. The reversibility of the electrochemical switching with these cubes are also shown. We attribute this unexpected change beyond classical understandings to the material-specific quantum mechanical electronic structures of the plasmonic materials.

Despite remarkable facileness and potential in forming a wide variety of heterostructured nanoparticles with extraordinary compositional and structural complexity, one-pot synthesis of multicomponent heterostructures is largely limited by the lack of fundamental mechanistic understanding, designing principles, and well-established, generally applicable chemical methods. Herein, we developed a one-pot heterointerfacial metamorphosis (1HIM) method that allows heterointerfaces inside a particle to undergo multiple equilibrium stages to form a variety of highly crystalline heterostructured nanoparticles at a relatively low temperature (<100 °C). As proof-of-concept experiments, it was shown that widely different single-crystalline semiconductor-metal anisotropic nanoparticles with synergistic chemical, spectroscopic, and band-gap-engineering properties, including a series of metal-semiconductor nanoframes with high structural and compositional tunability, can be formed by using the 1HIM approach. 1HIM offers a new paradigm to synthesize previously unobtainable or poorly controllable heterostructures with unique or synergistic properties and functions.

Polyampholyte (PA) hydrogels have great potential for biomedical applications, owing to their high toughness and good self-recovery and self-healing (SELF) behavior in addition to their physical properties similar to human tissue. However, their implementation as practical biomedical skin patches or wearable devices has so far been limited by their insufficient transdermal adhesion strength. In this work, a new polyampholytic terpolymer (PAT) hydrogel with enhanced skin adhesion was developed using a novel and simple strategy that tunes the structure of ion-pair associations (IPAs), acting as cross-links, in the hydrogel via adding an extra neutral monomer component into the network without changing the total charge balance. The PAT hydrogels were synthesized by the terpolymerization of the neutral monomer N , N -dimethylacrylamide (DMAAm) (or 2-hydroxyethyl methacrylate (HEMA)) as well as the cationic monomer 3-(methacryloylamino) propyl-trimethylammonium chloride (MPTC) and the anionic monomer sodium p -styrenesulfonate (NaSS). Their IPA, which determines their network structure, was modulated by varying the feed concentration of the neutral monomer, C nm . An increase of C nm within an optimized C nm window (0.3-0.4 M) decreased the cross-linking density (strength and density of the IPAs) of the PAT hydrogels, reducing the softening temperature and Young's modulus, which increased compliance but maintained sufficient mechanical strength and thereby maximized the contact surface and enhanced skin adhesion. The DMAAm monomers, compared to the HEMA monomers, produced the higher skin adhesion of the PAT hydrogel, which was explained by the difference in their reactivity to the MPTC and NaSS. This study demonstrated this new method to develop the PAT hydrogels with excellent skin adhesion and biocompatibility while maintaining good toughness, compliance, and SELF behavior and the potential of the PAT hydrogels for biomedical skin patches and wearable devices.

Despite their extraordinary mechanosensitivities, most channel-like crack-based strain sensors are limited by their poor levels of stretchability and linearity. This work presents a simple yet efficient way of modulating the cracking structure of thin metal films on elastomers to facilitate the development of high-performance wearable strain sensors. A net-shaped crack structure based on a thin platinum (Pt) film can be produced by coating an elastomer surface with M13 bacteriophages (phages) and consequently engineering the surface strain upon stretching. This process produces a Pt-on-phage (PoP) strain sensor that simultaneously exhibits high levels of stretchability (24%), sensitivity (maximum gauge factor ≈ 845.6 for 20-24%), and linearity ( R 2 ≈ 0.988 up to 20%). In addition, the sensor performance can be further modulated by either changing the phage coating volume or adding a silver nanowire coating to the PoP sensor film. The balanced strain-sensing performance, combined with fast response times and high levels of mechanical flexibility and operational stability, enables the devices to detect a wide range of human motions in real time after being attached to various body parts. Furthermore, PoP-based strain sensors can be usefully extended to detect more complex multidimensional strains through further strain engineering on a cross-patterned PoP film.

Bioreporters, microbial species genetically engineered to provide measurable signals in response to specific chemicals, have been widely investigated as sensors for biomedical and environmental monitoring. More specifically, the bioreporter encapsulated within a biocompatible material, such as a hydrogel that can provide a suitable microenvironment for its prolonged activity as well as efficient scalable production, has been viewed as a more broadly applicable mode of biosensors. In this study, alginate-based microbeads encapsulated with the bacterial bioreporter capable of expressing green fluorescence protein in response to nitro compounds (e.g., trinitrotoluene and dinitrotoluene) are developed as biosensors. To significantly enhance the sensitivity of the microbial-based microbead biosensors, "multifaceted" modification strategies are simultaneously employed: (1) multiple genetic modifications of the bioreporter, (2) tuning the physicomechanical properties of the encapsulating microbeads, (3) controlling the initial cell density within the microbeads, and (4) enrichment of nitro compounds inside microbeads via functional nanomaterials. These microbial and microenvironmental engineering approaches combine to significantly enhance the sensing capability, even allowing highly sensitive remote detection under a low-vapor phase. Thus, the strategy developed herein is expected to contribute to various cell-based biosensors.

Plasmonic nanoparticles are widely exploited in diverse bioapplications ranging from therapeutics to biosensing and biocomputing because of their strong and tunable light-matter interactions, facile and versatile chemical/biological ligand modifications, and biocompatibility. With the rapid growth of nanobiotechnology, understanding dynamic interactions between nanoparticles and biological systems at the molecular or single-particle level is becoming increasingly important for interrogating biological systems with functional nanostructures and for developing nanoparticle-based biosensors and therapeutic agents. Therefore, significant efforts have been devoted to precisely design and create nano-bio interfaces by manipulating the nanoparticles' size, shape, and surface ligand interactions with complex biological systems to maximize their performance and avoid unwanted responses, such as their agglomeration and cytotoxicity. However, investigating physicochemical interactions at the nano-bio interfaces in a quantitative and controllable manner remains challenging, as the interfaces involve highly complex networks between nanoparticles, biomolecules, and cells across multiple scales, each with a myriad of different chemical and biological interactions. A lipid bilayer is a membrane made of two layers of lipid molecules that forms a barrier around cells and plays structural and functional roles in diverse biological processes because they incorporate and present functional molecules (such as membrane proteins) with lateral fluidity. Plasmonic nanoparticles conjugated on lipid membranes provide reliable analytical labels and functional moieties that allow for studying and manipulating interactions between nanoparticles and molecules with single-particle resolution; they also serve as efficient tools for applying optical, mechanical, and thermal stimuli to biological systems, which stem from plasmonic properties. Recently, new opportunities have emerged by interfacing nanoparticle-modified lipid bilayers (NLBs) with complex systems such as molecular circuits and living systems. In this Account, we briefly review how plasmonic properties can be beneficially harnessed on lipid bilayer membranes to investigate the structures and functions of cellular membranes and to develop new platforms for biomedical applications. In particular, we discuss the versatility of supported lipid bilayers (SLBs), which are planar lipid bilayers on hydrophilic substrates, as dynamic biomaterials that provide lateral fluidity and cell membrane-like environments. We then summarize our efforts to create a quantitative analytical platform utilizing nanoparticles as active building blocks and SLBs as integrative substrates. Through this bottom-up approach, various functionalized nanoparticles have been introduced onto lipid bilayers to render nanoparticle-nanoparticle, nanoparticle-lipid bilayer, and biomolecule-lipid bilayer interfaces programmable. Our system provides a new class of tools for studying thermodynamics and kinetics in complex networks of nanostructures and for realizing unique applications in biosensing and biocomputing.

There have been extensive efforts to develop competitive electrocatalysts using carbon black (CB) supports for high-performance proton-exchange membrane fuel cells with less usage of Pt. Herein, we propose a very promising electrocatalyst architecture based on the three-dimensional Pt/indium tin oxide (ITO)/CB support structure which was enabled by a nonconventional deposition process ensuring very uniform impregnation of Pt and ITO nanoparticles into the CB network. The unusual scales of the Pt (∼1.9 nm) and ITO (∼5.6 nm) nanoparticles were directly related to unexpectedly better performance of the electrocatalytic activities. As a highlight, the electrochemical surface area of the electrocatalyst was maintained very well after the 3000 cycle-accelerated durability evaluation by demonstrating an excellent retention of ∼74.9%. Particularly, the CO tolerance exhibited a low value of ∼0.68 V as the absorption current peak, compared to ∼0.79 V for a commercial Pt/CB catalyst containing twice more Pt.

A surface-enhanced Raman scattering (SERS) sensor comprising silver nanowires (AgNWs) and genetically engineered M13 bacteriophages expressing a tryptophan-histidine-tryptophan (WHW) peptide sequence (BPWHW) was fabricated by simple mixing of BPWHW and AgNW solutions, followed by vacuum filtration onto a glass-fiber filter paper (GFFP) membrane. The AgNWs stacked on the GFFP formed a high density of SERS-active hot spots at the points of nanowire intersections, and the surface-coated BPWHW functioned as a bioreceptor for selective pesticide detection. The BPWHW-functionalized AgNW (BPWHW/AgNW) sensor was characterized by scanning electron microscopy, confocal scanning fluorescence microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. The Raman signal enhancement and the selective pesticide SERS detection properties of the BPWHW/AgNW sensor were investigated in the presence of control substrates such as wild-type M13 bacteriophage-decorated AgNWs (BPWT/AgNW) and undecorated AgNWs (AgNW). The BPWHW/AgNW sensor exhibited a significantly higher capture capability for pesticides, especially paraquat (PQ), than the control SERS substrates, and it also showed a relatively higher selectivity for PQ than for other bipyridylium pesticides such as diquat and difenzoquat. Furthermore, as a field application test, PQ was detected on the surface of PQ-pretreated apple peels, and the results demonstrated the feasibility of using a paper-based SERS substrate for on-site residual pesticide detection. The developed M13 bacteriophage-functionalized AgNW SERS sensor might be applicable for the detection of various pesticides and chemicals through modification of the M13 bacteriophage surface peptide sequence.

Multicomponent nanoparticles that incorporate multiple nanocrystal domains into a single particle represent an important class of material with highly tailorable structures and properties. The controlled synthesis of multicomponent NPs with 3 or more components in the desired structure, particularly anisotropic structure, and property is, however, challenging. Here, we developed a polymer and galvanic replacement reaction-based transformative heterointerface evolution (THE) method to form and tune gold-copper-silver multimetallic anisotropic nanoparticles (MAPs) with well-defined configurations, including structural order, particle and junction geometry, giving rise to extraordinarily high tunability in the structural design, synthesis and optical property of trimetallic plasmonic nanoantenna structures. MAPs can easily, flexibly integrate multiple surface plasmon resonance (SPR) peaks and incorporate various plasmonic field localization and enhancement within one structure. Importantly, a heteronanojunction in these MAPs can be finely controlled and hence tune the SPR properties of these structures, widely covering UV, visible and near-infrared range. The development of the THE method and new findings in synthesis and property tuning of multicomponent nanostructures pave ways to the fabrication of highly tailored multicomponent nanohybrids and realization of their applications in optics, energy, catalysis and biotechnology.

Plasmonic coupling-based electromagnetic field localization and enhancement are becoming increasingly important in chemistry, nanoscience, materials science, physics, and engineering over the past decade, generating a number of new concepts and applications. Among the plasmonically coupled nanostructures, metal nanostructures with nanogaps have been of special interest due to their ultrastrong electromagnetic fields and controllable optical properties that can be useful for a variety of signal enhancements such as surface-enhanced Raman scattering (SERS). The Raman scattering process is highly inefficient, with a very small cross-section, and Raman signals are often poorly reproducible, meaning that very strong, controllable SERS is needed to obtain reliable Raman signals with metallic nanostructures and thus open up new avenues for a variety of Raman-based applications. More specifically, plasmonically coupled metallic nanostructures with ultrasmall (∼1 nm or smaller) nanogaps can generate very strong and tunable electromagnetic fields that can generate strong SERS signals from Raman dyes in the gap, and plasmonic nanogap-enhanced Raman scattering can be defined as Raman signal enhancement from plasmonic nanogap particles with ∼1 nm gaps. However, these promising nanostructures with extraordinarily strong optical signals have shown limited use for practical applications, largely due to the lack of design principles, high-yield synthetic strategies with nanometer-level structural control and reproducibility, and systematic, reliable single-molecule/single-particle-level studies on their optical properties. All these are extremely important challenges because even small changes (<1 nm) in the structure of the coupled plasmonic nanogaps can significantly affect the plasmon mode and signal intensity. In this Account, we examine and summarize recent breakthroughs and advances in plasmonic nanogap-enhanced Raman scattering with metal nanogap particles with respect to the design and synthesis of plasmonic nanogap structures, as well as ultrasensitive and quantitative Raman signal detection using these structures. The applications and prospects of plasmonic nanogap particle-based SERS are also discussed. In particular, reliable synthetic and measurement strategies for plasmonically coupled nanostructures with ∼1 nm gap, in which both the nanogap size and the position of a Raman-active molecule in the gap can be controlled with nanometer/sub-nanometer-level precision, can address important issues regarding the synthesis and optical properties of plasmonic nanostructures, including structural and signal reproducibility. Further, single-molecule/single-particle-level studies on the plasmonic properties of these nanogap structures revealed that these particles can generate ultrastrong, quantifiable Raman signals in a highly reproducible manner.

An efficient direct phthalic anhydride-mediated one-pot glycosylation method employing anomeric hydroxy arabinofuranose as glycosyl donor and triflic anhydride as activating agent has been developed. This method afforded the desired di- and oligoarabinofuranosides in good yields even in gram scale glycosylation when t-butylphthalic anhydride was used. Moreover, our new method can be further extended to the syntheses of repeating oligoarabinofuranoside and tetradecasaccharide arabinan motif found in mycobacterial cell wall.

An electron-transfer strategy using low-valent iron pentacarbonyl [Fe(CO) 5 ] to generate radical species from alkyl iodides was achieved. A range of pyrrolidines, tetrahydrofurans, and carbocycles were synthesized via 5-exo cyclization reactions of alkyl radical intermediates generated by electron transfer from a system involving Fe(CO) 5 , 1,10-phenanthroline, and diisopropylamine. Moreover, tandem addition reactions with Michael acceptors were also explored. Photophysical and electrochemical studies support a mechanism that involves electron transfer from the low-valent Fe reductant to alkyl iodide.

We report a robust one-dimensional (1D) nanoparticle-assembly strategy that uses the self-assembly of nanoparticles with ligand and thermal controls, polyethylene glycol (PEG) with thiol and carboxyl groups, and nanoparticle oligomer and polymer codewetting process to form ultralong and continuous 1D nanochains. The 1D nanochains were assembled with closely packed 1D nanoparticle oligomer building blocks, elongated and buttressed by dynamic 1D PEG templates formed on a hydrophobic surface via anisotropic spinodal dewetting. Using this strategy, nanoparticle-packed 1D nanochains (∼1 nm interparticle spacing) were fabricated with ∼60 nm-width and a few to >10 μm-length (nearly 20 μm in some cases) from 20 nm gold nanoparticles. Our findings offer insights and open revenues for particle assembly processes and, as given by 'universality in colloid aggregation', should be readily applicable to various nanoparticles.

The design, synthesis and control of plasmonic nanostructures, especially with ultrasmall plasmonically coupled nanogap (∼1 nm or smaller), are of significant interest and importance in chemistry, nanoscience, materials science, optics and nanobiotechnology. Here, we studied and established the thiolated DNA-based synthetic principles and methods in forming and controlling Au core-nanogap-Au shell structures [Au-nanobridged nanogap particles (Au-NNPs)] with various interior nanogap and Au shell structures. We found that differences in the binding affinities and modes among four different bases to Au core, DNA sequence, DNA grafting density and chemical reagents alter Au shell growth mechanism and interior nanogap-forming process on thiolated DNA-modified Au core. Importantly, poly A or poly C sequence creates a wider interior nanogap with a smoother Au shell, while poly T sequence results in a narrower interstitial interior gap with rougher Au shell, and on the basis of the electromagnetic field calculation and experimental results, we unraveled the relationships between the width of the interior plasmonic nanogap, Au shell structure, electromagnetic field and surface-enhanced Raman scattering. These principles and findings shown in this paper offer the fundamental basis for the thiolated DNA-based chemistry in forming and controlling metal nanostructures with ∼1 nm plasmonic gap and insight in the optical properties of the plasmonic NNPs, and these plasmonic nanogap structures are useful as strong and controllable optical signal-generating nanoprobes.

Observation of individual single-nanoparticle reactions provides direct information and insight for many complex chemical, physical, and biological processes, but this is utterly challenging with conventional high-resolution imaging techniques on conventional platforms. Here, we developed a photostable plasmonic nanoparticle-modified supported lipid bilayer (PNP-SLB) platform that allows for massively parallel in situ analysis of the interactions between nanoparticles with single-particle resolution on a two-dimensional (2D) fluidic surface. Each particle-by-particle PNP clustering process was monitored in real time and quantified via analysis of individual particle diffusion trajectories and single-particle-level plasmonic coupling. Importantly, the PNP-SLB-based nanoparticle cluster growth kinetics result was fitted well. As an application example, we performed a DNA detection assay, and the result suggests that our approach has very promising sensitivity and dynamic range (high attomolar to high femtomolar) without optimization, as well as remarkable single-base mismatch discrimination capability. The method shown herein can be readily applied for many different types of intermolecular and interparticle interactions and provide convenient tools and new insights for studying dynamic interactions on a highly controllable and analytical platform.

Decellularization of tissues or organs can provide an efficient strategy for preparing functional scaffolds for tissue engineering. Microstructures of native extracellular matrices and their biochemical compositions can be retained in the decellularized matrices, providing tissue-specific microenvironments for efficient tissue regeneration. Here, we report the versatility of liver extracellular matrix (LEM) that can be used for two-dimensional (2D) coating and three-dimensional (3D) hydrogel platforms for culture and transplantation of primary hepatocytes. Collagen type I (Col I) has typically been used for hepatocyte culture and transplantation. In this study, LEM was compared with Col I in terms of biophysical and mechanical characteristics and biological performance for enhancing cell viability, differentiation, and hepatic functions. Surface properties of LEM coating and mechanical properties and gelation kinetics of LEM hydrogel could be manipulated by adjusting the LEM concentration. In addition, LEM hydrogel exhibited improved elastic properties, rapid gelation, and volume maintenance compared to Col I hydrogel. LEM coating significantly improved hepatocyte functions such as albumin secretion and urea synthesis. More interestingly, LEM coating upregulated hepatic gene expression of human adipose-derived stem cells, indicating enhanced hepatic differentiation of these stem cells. The viability and hepatic functions of primary hepatocytes were also significantly improved in LEM hydrogel compared to Col I hydrogel both in vitro and in vivo. Albumin and hepatocyte transcription factor expression was upregulated in hepatocytes transplanted in LEM hydrogels. In conclusion, LEM can provide functional biomaterial platforms for diverse applications in liver tissue engineering by promoting survival and maturation of hepatocytes and hepatic commitment of stem cells. This study demonstrates the feasibility of decellularized matrix for both 2D coating and 3D hydrogel in liver tissue engineering.

We report novel phage-based array chips that are optically readable for cell proliferation and morphology assays. Using M13 phages that were engineered to display RGD on its major coat proteins and/or immobilize FGFb on its minor coat proteins, we prepared arrays of phage spot matrices composed of self-assembled nanofibrous network structures. We cultured fibroblasts on the arrays and, using surface plasmon resonance (SPR) spectroscopy, monitored the effects of the biochemical cues displayed by the phage on cell proliferation and morphology. This study demonstrates the utility of engineered phages as promising coating materials for lab-on-a-chip (LOC) platforms, allowing sensitive monitoring of the effects of functional peptides on cell growth. Phage-chips have great potential for use as high-throughput screening systems for biochemical assays and biosensors and the discovery of novel drugs., (© 2011 American Chemical Society)

We investigated a dependence of the grating formation on the temperature in polymeric photorefractive (PR) composite, in terms of magnitude and buildup speed of the PR grating. For polymeric PR materials, the temperature is one of the most important factors together with the external electric field because it is closely related on photocharge generation efficiency, mobility of generated carrier, electro-optic coefficient tensor, and so on. Above the glass transition temperature, the diffraction efficiency of degenerate four-wave mixing decreased with increasing the temperature; it can be explained with the magnitude of space-charge field and the electro-optic behavior at different temperatures. The space-charge field decreased linearly with increasing temperature due to a decrease in the photocharge generation efficiency and an increase in the hole detrapping by the high dark conductivity. Also as we expected, the PR grating buildup speed, which is strongly dependent on the photoconductivity, steeply decreased with increasing the temperature, and its tendency was similar to the temperature dependence of the phase shift.

The growth-inhibiting activity of Coptis japonica (Makino) root-derived materials toward eight human intestinal bacteria was examined using an impregnated paper disk method and compared to that of four commercially available isoquinoline alkaloids [berberine sulfate (BS), berberine iodide (BI), palmatine chloride (PC), and palmatine sulfate(PS)], as well as that of Thea sinensis leaf-derived epigallocatechin gallate (EGCG). The biologically active constituents of the Coptis extract were characterized as the isoquinoline alkaloids berberine chloride (BC), palmatine iodide (PI), and coptisine chloride (CC) by spectral analysis. The growth responses varied with both chemical and bacterial strain used. In a test using 500 microg/disk, BC and PI produced a clear inhibitory effect against Bifidobacterium longum, Bifidobacterium bifidum, Clostridium perfringens, and Clostridium paraputrificum, whereas weak or no inhibition was observed in Bifidobacterium adolescentis, Lactobacillus acidophilus, Lactobacillus casei, and Escherichia coli. At 1000 microg/ disk, CC revealed weak or no growth inhibition toward all test bacteria, whereas EGCG exhibited weak growth inhibition against only C. perfringens and C. paraputrificum. Among various isoquinoline alkaloids, BC exhibited more potent inhibitory activity toward C. perfringens than BI and BS, whereas the inhibitory effect was more pronounced in PI compared to PC and PS. The Coptis root-derived materials did not promote growth of B. longum and C. perfringens.