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DNA origami requires long scaffold DNA to be aligned with the guidance of short staple DNA strands. Scaffold DNA is produced in Escherichia coli as a form of the M13 bacteriophage by rolling circle amplification (RCA). This study shows that RCA can be reconfigured by reducing phage protein V (pV) expression, improving the production throughput of scaffold DNA by at least 5.66-fold. The change in pV expression was executed by modifying the untranslated region sequence and monitored using a reporter green fluorescence protein fused to pV. In a separate experiment, pV expression was controlled by an inducer. In both experiments, reduced pV expression was correlated with improved M13 bacteriophage production. High-cell-density cultivation was attempted for mass scaffold DNA production, and the produced scaffold DNA was successfully folded into a barrel shape without compromising structural quality. This result suggested that scaffold DNA production throughput can be significantly improved by reprogramming the RCA in E. coli.

Icephobic surfaces have gained immense attention owing to their significant roles in decreasing the energy consumption of refrigerators and in improving safety issues by preventing the formation of ice on them. Superhydrophobic surfaces incorporating micro- or nanoscale roughness and hydrophobic functional groups have been shown to prevent ice accumulation. Herein, we report a simple, low-cost, and solution-based one-step process for the production of superhydrophobic surfaces with three-dimensional (3D) self-assembled structures. The controlled hydrolysis and polycondensation of n-octadecyltrichlorosilane (OTS-Cl) in an acetone solution produced a highly uniform superhydrophobic surface on various substrates such as glass, metals, and polymers without the limitation of the surface curvature structure. The as-prepared 3D self-assembled surface exhibited a very high contact angle of 161.7° and a low contact hysteresis of 1.47°. The solvent type, H2O content in acetone, and carbon chain length of the silane compound were critical in the formation of self-assembled nanostructures. The thickness of the superhydrophobic 3D self-assembled structure could be varied by controlling the surface properties of the glass substrate. In addition, a novel octadecyl silica nanosquare plate structure was formed as an intermediate for the microlamella structure. The water drop impact experiments on the 3D self-assembled superhydrophobic glass substrates at low temperatures (T < -25 °C) showed that the as-prepared superhydrophobic glass possessed a high impalement threshold for water contact, resulting in excellent and stable icephobic properties. The preparation method proposed in this study is scalable and can be used on a flat glass surface or in a glass vial inside a glass tube. Moreover, it can be applied to various substrates such as metals and polyurethane surfaces with curvature. Therefore, the solution-based self-assembly method proposed in this study is a promising approach to produce superhydrophobic and icephobic surfaces on a wide range of substrates regardless of their structure and properties.

Responsive polymers, undergoing changes in light absorption and emission properties in response to stimuli, have been extensively investigated as key smart materials. Here, we report the nature underlying the optical and spectroscopic responses in linear polydiacetylenes, responsive conjugated polymers well-known for a blue-to-red transition upon specific stimuli. By means of a theoretical strategy mimicking entire empirical treatments, we reveal that hyperconjugation between the side chain and conjugated backbone signals their response: the first understanding at the electronic state level, unlike molecular conformational arguments prevailing since topochemical polymerization was discovered by Wegner in 1972. We provide quantitative exploration of (i) the thermochromic response, and (ii) applied functions showing reversible and irreversible chromism. The present work should lead to a new angle for polydiacetylene-based materials design from the hyperconjugation perspective.

Despite their high potency, the widespread implementation of natural antimicrobial peptides is still challenging due to their low scalability and high hemolytic activities. Herein, we address these issues by employing a modular approach to mimic the key amino acid residues present in antimicrobial peptides, such as lysine, leucine, and serine, but on the highly biocompatible poly(ethylene glycol) (PEG) backbone. A series of these PEG-based peptides (PEGtides) were developed using functional epoxide monomers, corresponding to each key amino acid, with several possessing highly potent bactericidal activities and controlled selectivities, with respect to their hemolytic behavior. The critical role of the composition and the structure of the PEGtides in their selectivities was further supported by coarse-grained molecular dynamic simulations. This modular approach is anticipated to provide the design principles necessary for the future development of antimicrobial polymers.

The general practice of photodynamic therapy (PDT) comprises repeated multiple sessions, where photosensitizers are repeatedly administered prior to each operation of light irradiation. To address potential problems arising from the total overdose of photosensitizer by such repeated injections, we here introduce an internalizing RGD peptide (iRGD) derivative (Ppa-iRGDC-BK01) that self-aggregates into an injectable single-component supramolecular depot. Ppa-iRGDC-BK01 is designed as an in situ self-implantable photosensitizer so that it forms a depot by itself upon injection, and its molecular functions (cancer cell internalization and photosensitization) are activated by sustained release, tumor targeting, and tumor-selective proteolytic/reductive cleavage of the iRGD segment. The experimental and theoretical studies revealed that when exposed to body temperature, Ppa-iRGDC-BK01 undergoes thermally accelerated self-assembly to form a supramolecular depot through the hydrophobic interaction of the Ppa pendants and the reorganization of the interpeptide hydrogen bonding. It turned out that the self-aggregation of Ppa-iRGDC-BK01 into a depot exerts a multiple-quenching effect on the photosensitivity to effectively prevent nonspecific phototoxicity and protect it from photobleaching outside the tumor, while enabling autonomous tumor rephotosensitization by long sustained release, tumor accumulation, and intratumoral activation over time. We demonstrate that depot formation through a single peritumoral injection and subsequent quintuple laser irradiations at intervals resulted in complete eradication of the tumor. During the repeated PDT, depot-implanted normal tissues around the tumor exhibited no phototoxic damage under laser exposure. Our approach of single-component photosensitizing supramolecular depot, combined with a strategy of tumor-targeted therapeutic activation, would be a safer and more precise operation of PDT through a nonconventional protocol composed of one-time photosensitizer injection and multiple laser irradiations.

Despite technological advances in biomolecule detections, evaluation of molecular interactions via potentiometric devices under ion-enriched solutions has remained a long-standing problem. To avoid severe performance degradation of bioelectronics by ionic screening effects, we cover probe surfaces of field effect transistors with a single film of the supported lipid bilayer, and realize respectable potentiometric signals from receptor–ligand bindings irrespective of ionic strength of bulky solutions by placing an ion-free water layer underneath the supported lipid bilayer. High-energy X-ray reflectometry together with the circuit analysis and molecular dynamics simulation discovered biochemical findings that effective electrical signals dominantly originated from the sub-nanoscale conformational change of lipids in the course of receptor–ligand bindings. Beyond thorough analysis on the underlying mechanism at the molecular level, the proposed supported lipid bilayer-field effect transistor platform ensures the world-record level of sensitivity in molecular detection with excellent reproducibility regardless of molecular charges and environmental ionic conditions., The design of bioelectronic devices that enables accurate detection of biomolecules in ionic solutions at physiologically-relevant concentrations remains a challenge. Here, the authors report a ion-impermeable supported lipid bilayer-assisted field-effect transistor platform for biomolecule detection.

Organic semiconductors are photonic and electronic materials with high luminescence, quantum efficiency, color tunability, and size-dependent optoelectronic properties. The self-assembly of organic molecules enables the establishment of a fabrication technique for organic micro- and nano-architectures with well-defined shapes, tunable sizes, and defect-free structures. DNAs, a class of biomacromolecules, have recently been used as an engineering material capable of intricate nanoscale structuring while simultaneously storing biological genetic information. Here, the up-to-date research on hybrid materials made from organic semiconductors and DNAs is presented. The trends in photonic and electronic phenomena discovered in DNA-functionalized and DNA-driven organic semiconductor hybrids, comprising small molecules and polymers, are observed. Various hybrid forms of solutions, arrayed chips, nanowires, and crystalline particles are discussed, focusing on the role of DNA in the hybrids. Furthermore, the recent technical advances achieved in the integration of DNAs in light-emitting devices, transistors, waveguides, sensors, and biological assays are presented. DNAs not only serve as a recognizing element in organic-semiconductor-based sensors, but also as an active charge-control material in high-performance optoelectronic devices.

Forster resonance energy transfer (FRET) is extremely sensitive to the separation distance between the donor and the acceptor which is ideal for probing such biological phenomena. Also, FRET-based probes have been developing for detecting an unamplified, low-abundance of target DNA. Here we describe the development of FRET based DNA sensor based on an accumulated QD system for detecting KRAS G12D mutation which is the most common mutation in cancer. The accumulated QD system consists of the polystyrene beads which surface is modified with carboxyl modified QDs. The QDs are sandwich-hybridized with DNA of a capture probe, a reporter probe with Texas-red, and a target DNA by EDC-NHS coupling. Because the carboxyl modified QDs are located closely to each other in the accumulated QDs, these neighboring QDs are enough to transfer the energy to the acceptor dyes. Therefore the FRET factor in the bead system is enhancing by the additional increase of 29.2% as compared to that in a single QD system. These results suggest that the accumulated nanobead probe with conjugated QDs can be used as ultrasensitive DNA nanosensors detecting the mutation in the various cancers.

Although the reversibility of 10, 12-pentacosadiynoic amino meta-acid (PCDA-mBzA) against temperature and pH was reported, the modulation of reversibility by ion adsorption at terminal functional group has not been investigated. In this work, we developed a simple method for modulating the reversibility of PCDA-mBzA films upon a thermal stimulus by cadmium ion adsorption inducing the breakage of the outer hydrogen bonding of two hydrogen bonds, which are responsible for the reversible properties of PCDA-mBzA. External reflection-Fourier transform infrared (ER-FTIR) analyses revealed that the hydrogen bonding between the carboxylic acid groups was broken through ion adsorption and only a single hydrogen bond between the amide groups remained in the PCDA-mBzA polymer. In addition, PCDA-mBzA films could recover their original property through cadmium ion desorption. These results present that the transition between reversibility and irreversibility can be modulated artificially simply through the adsorption and desorption of metal ions.

Organic semiconductor materials for fabricating organic light emitting diodes (OLEDs) have attracted significant attention in the field of novel optical and optoelectronic devices. Particulation of OLEDs’ emitting materials in small-scale has been limited only to tris(8-hydroxyquinoline) aluminum (Alq3) that emits green-light. In this study, we attempted to fabricate, for the first time, red-light emitting nanoparticles of phosphorescent organic semiconductor of bis(1-phenylisoquinoline) (acetylacetonate) iridium (Ir(piq)2(acac)). Rectangular particles with length and thickness of ∼2 μm and ∼50 nm were fabricated with guidance of cetyltrimethylammonium bromide (CTAB) and micro-plates with length and thickness of ∼5 μm and ∼100 nm were fabricated by sodium dodecyl sulfate (SDS). By contrast, single-stranded DNA (ssDNA) induced nano-rods with dimension of ∼400 nm in length and 100 nm in thickness. Hence, the choice of guiding agents resulted in distinctive crystal characteristic so that the nanorods by ssDNAs showed UV absorption with a red-shift in metal-ligand charge transfer (MLCT) by 54 nm whereas the particles by surfactants did 35 nm compared to the dissolved precursor. Higher was the ssDNA-guided nanorods in relative phosphorescence of the intensity at 610 nm over that at 695 nm than the surfactant-guided particles.

In this study, we developed effective carbon-rich Al2O3 interlayers for flexible moisture barrier films. The carbon-rich Al2O3 films were deposited with excessive supply of trimethylaluminum (TMA) precursor. The five-layer structure was made with alternate layers of low-carbon Al2O3 and carbon-rich Al2O3 and the water vapor transmission rate (WVTR) of 3.3 × 10 −4 g/(m2·day) was demonstrated. The WVTR of the multilayer films is reduced by 36% compared to 25 nm thick single Al2O3 barrier film. The WVTR of the five-layer film shows increase of 86% after 1,000 bending at a 1.5 cm radius, while single Al2O3 thin films increased by 367%.

Biodegradable polymers have been extensively used in biomedical applications, ranging from regenerative medicine to medical devices. However, the acidic byproducts resulting from degradation can generate vigorous inflammatory reactions, often leading to clinical failure. We present an approach to prevent acid-induced inflammatory responses associated with biodegradable polymers, here poly(lactide- co-glycolide), by using oligo(lactide)-grafted magnesium hydroxide (Mg(OH)2) nanoparticles, which neutralize the acidic environment. In particular, we demonstrated that incorporating the modified Mg(OH)2 nanoparticles within degradable coatings on drug-eluting arterial stents efficiently attenuates the inflammatory response and in-stent intimal thickening by more than 97 and 60%, respectively, in the porcine coronary artery, compared with that of drug-eluting stent control. We also observed that decreased inflammation allows better reconstruction of mouse renal glomeruli in a kidney tissue regeneration model. Such modified Mg(OH)2 nanoparticles may be useful to extend the applicability and improve clinical success of biodegradable devices used in various biomedical fields.

The effect of temperature on the two-dimensional phase of 10,12-pentacosadiynoic acid (PCDA) Langmuir films at the air/water interface was investigated. The temperature of the Langmuir films was precisely controlled from 5 to 50 °C and their surface isotherms and in-situ visible absorption spectra were acquired. Depending on the temperature, the PCDA Langmuir films were found to be classified into a liquid-condensed (low temperatures, 5 and 25 °C) and a liquid-expanded phase (high temperatures, 40 and 50 °C). After polymerizing the PCDA Langmuir films with 254 nm UV light at the specific temperatures, the films were transferred to hydrophobic glass using the Langumir-Schaefer (LS) method. Upon thermal and pH stimuli, their chromatic transition characteristics were analyzed by visible spectroscopy. The liquid-condensed films were found to be more susceptible to thermal stimulus than the liquid-expanded films. The latter also showed remarkable chromatic stability against the pH in the region from 2 to 11, compared to the former. Thus, when sturdy films are required, the multilayered PCDA LS films prepared at the liquid-expanded phase are more suitable than the liquid-condensed films, and vice versa. This result is expected to be very useful for controlling the sensitivity and stability of polydiacetylene-based sensory systems simply by changing the polymerization temperature, even without synthesizing new monomers.

Five different shapes of magnesium hydroxide (Mg(OH)2) particles (Plate-S, Plate-N, Disk, Whisker, and Fiber) were synthesized and added to biopolymer (i.e., Poly(lactic-co-glycolic acid) (PLGA)) composite to improve their mechanical and biological properties. The PLGA composite films including Mg(OH)2 particles were prepared by a solvent casting method. Their mechanical and biological properties were compared according to the composites containing different shapes of Mg(OH)2 particles. Among them, the fiber shape of Mg(OH)2 provided the highest mechanical strength, and anti-inflammation and anti-bacterial activity to PLGA films among other forms. This study demonstrated a new strategy for the design of biomaterials by controlling the form of inorganic additives.

Plasmonic nanocrystals, which exhibit extraordinary optical properties, are challenging to grow in selective positions with a cost-effective and high-throughput process. We demonstrate that plasmonic isotropic gold nanospheres (AuNSs) can be selectively synthesized on wafer-scale rigid and flexible substrates at room temperature by laser irradiation. First, we prepare gold nanocolumn (AuNC) thin films on sapphire and polydimethylsiloxane substrates with glancing angle deposition (GAD). Then, a KrF excimer laser is exposed at selected positions with a 24 ns pulse duration. Finally, highly isotropic AuNSs as plasmonic nanocrystals are synthesized at the targeted positions. We suggest that the formation of such isotropic AuNSs is caused by reshaping from the top of the AuNCs; this is verified by the temperature distribution in the AuNCs during laser irradiation through finite element method simulations. We further investigate the formation of AuNSs by varying the laser energy density and the kind of substrate. By using a simple mask process, we demonstrate patterning of the letters “KIST” via selectively grown AuNSs on a flexible substrate. The simple laser irradiation process on GAD-grown metal NC thin films is expected to be a promising method for scalable synthesis of plasmonic isotropic NSs at targeted positions with a rapid process and at room temperature.

An analytical method based on a fabricated analytical disc was developed using a phosphonate-immobilized quartz substrate for the rapid analysis of uranium. Phosphonate groups selectively adsorb uranium dissolved in a solution through the formation of stable complexes. The uranium concentration and isotopic ratios in the sample can rapidly be determined by measuring the radioactivity of the adsorbed uranium on the analytical disc using alpha-particle spectrometry. The chemical structure and elemental composition of the fabricated disc were analyzed by XPS, and the adsorption properties were evaluated as functions of pH of a sample solution, reaction time, and adsorbate concentration, as well as reusability and selectivity, using alpha-particle spectrometry, ICP-OES, and ICP-MS. An analytical method was developed based on these properties and validated with prepared uranium solutions by assessing the chemical recovery yield, relative error, and relative standard deviation. The developed method is expected to be used for on-the-spot uranium analysis.

By utilizing the capillary-force-driven action, a novel polydiacetylene-based sensor on the porous silica plate was developed within 30 s for π-diacetylene monomers with variable chain lengths. This method enables one to utilize diacetylene monomers even with the shorter alkyl chain length of C18-C21, which has not been possible with conventional methods. The invented sensor platform employing shorter monomers was found to perform better, as was demonstrated for gaseous and aqueous analytes, i.e., ammonia gas and nucleic acids in aqueous phase. This new polydiacetylene platform opens up the development of quick and easy fabrication and the use of chemical and biochemical chips.

Revealing the nature of chain packing in conjugated polymer nanoparticles (CPNs) is one of the important issues to polymer physics research. Surfactant-stabilized CPNs in water show significantly enhanced luminescence intensity in comparison to small molecular organic dyes and single polymer chains dissolved in solvents. The importance of the conjugated polymer structure in nanomaterials is undoubted. However, details of the relationship between alignment of conjugated polymer backbone in CPNs and its luminescent property have not been established. Furthermore, there are yet no methods that can predict the atom-resolved structure of conjugated polymer in the CPNs. Herein, we employ coarse-grained (CG) molecular dynamic simulations to investigate the structure of phase-separated film and the film shattering process for a mixture of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and 1,2-dioctanoyl-sn-glycero-3-phosphocholine (D8PC). The π...

Encapsulation of fluorophores in silica matrix offers many advantages such inhibition of photobleaching and possibilities for ratiometric pH sensing. Dualfluorophore pH-responsive silica microspheres, incorporating pyranine (HPTS) and rhodamine B isothiocyanate (RBITC), were synthesized by Stober method, followed layer-by-layer depositions. The resulting dual-fluorophore silica microspheres were then characterized by SEM, TEM, fluorescence spectroscopy and imaging. The incorporation of two dyes in the microspheres allowed ratiometric quantification of pH. The ratiometric approach has been proven to reduce the influences of external perturbations and unequal dye concentration in silica matrix during measurements. The dynamic range for pH was from 1.5 to 4. The sensing microspheres could be applied to determine acidic pH. Additionally, the sensing microspheres exhibited a high colloidal and long-term stability and also allow a fast detection of pH due the porosity of the microspheres. Such structured microspheres could be optimized, using multiple dyes for multianalyte detection.

Hydrogel-based sensory structures were developed by embedding polydiacetylene supramolecules into poly-(ethylene glycol)-diacrylate (PEG-DA) to detect chemical gases and cyclodextrin and to determine pH values on the basis of a fluorescence change. We found the optimal condition for patterning-fabrication by controlling the volumetric mixture ratio of the water-soluble PEG-DA and aqueous polydiacetylene vesicle solution. Then, we determined that this hydrogel-based polydiacetylene structure optically responded selectively against vapor-phase targets: ammonia, ethanol, and aldehyde; aqueous solutions with various pH values; and cyclodextrin derivatives. These results could be extended to various label-free sensing applications of hydrogel-based chemo-biosensors.

Diacetylene (DA) is an amphiphilic structure and has been studied as a variety of PDA-based chemosensors. However, the prospect of using diacetylene (DA) as dopant of polyaniline (PANI) is yet to be reported. In this study, new amphiphilic PCDA-taurine and PCDA-pBzS dopants were synthesized by changing the primary functional group to a sulfonic group. These polymerizable dopants are photopolymerized by UV irradiation in PANI solution. Thereby we expect to enhance the thermal stability and sustain the conductivity of PANI. The polymerizable dopants were characterized by FT-IR, NMR, and GC-MS. PANI with polymerizable dopants was analyzed by resonance Raman spectroscopy (RRS). The thermal stability and conductivity of PANI were characterized by thermogravimetric analysis (TGA). Comparing the TGA results of PANI doped with general dopants with PANI doped with polymerizable dopants, we found that PANI with polymerizable dopants showed enhanced thermal stability.

Gold (Au) colloids are becoming ubiquitous across biomedical engineering, solar energy conversion, and nano-optics. Such universality has originated from the exotic plasmonic effect of Au colloids (i.e., localized surface plasmon resonance (LSPRs)) in conjunction with the versatile access to their synthetic routes. Herein, we introduce a previously undiscovered usage of Au colloids for advancing cryoprotectants with significant ice recrystallization inhibition (IRI). Oligopeptides inspired by the antifreeze protein (AFP) and antifreeze glycoprotein (AFGP) are attached onto the surface of well-defined Au colloids with the same sizes but different shapes. These AF(G)P-inspired Au colloids can directly adsorb onto a growing ice crystal via the synergistic interplay between hydrogen bonding and hydrophobic groups, in stark contrast to their bare Au counterparts. Dark-field optical microscopy analyses, benefiting from LSPR, allow us to individually trace the in situ movement of the antifreezing Au colloids during ice growth/recrystallization and clearly evidence their direct adsorption onto the growing ice crystal, which is consistent with theoretical predictions. With the assistance of molecular dynamics (MD) simulations, we evidently attribute the IRI of AF(G)P-inspired Au colloids to the Kelvin effect. We also exploit the IRI dependence on the Au colloidal shapes; indeed, the facet contacts between ice and Au colloids can be better than the point-like counterparts in terms of IRI. The design principles and predictive theory outlined in this work will be of broad interest not only for the fundamental exploration of the inhibition of ice growth but also for enriching the application of Au colloids.

A new polydiacetylene lipid/human olfactory receptor nano-assembly was fabricated for the visual detection of an odorant for the first time. The assembly consisted of phospholipid-mixed polydiacetylenes (PDAs) and human olfactory receptors (hORs) in detergent micelles. To overcome the limitations of bioelectronic noses, hOR-embedded chromatic complexes (PDA/hORs) were developed, introducing PDAs that showed color and fluorescence transitions against various stimuli. The chromatic nanocomplexes reacted with target molecules, showing a fluorescence intensity increase in a dose-dependent manner and target selectivity among various odorants. As a result, a color transition of the assembly from blue to purple occurred, allowing the visual detection of the odorant geraniol. Through circular dichroism (CD) spectroscopy and a tryptophan fluorescence quenching method, the structural and functional properties of the hORs embedded in the complexes were confirmed. Based on this first work, future array devices, integrating multiple nano-assemblies, can be substantiated and utilized in environmental assessment and analysis of food quality.

The prototype generation IV sodium-cooled fast reactor (PGSFR) has been developed by the Korea Atomic Energy Research Institute. This reactor uses sodium as a reactor coolant to transfer the core heat energy to the turbine. Sodium has chemical characteristics that allow it to violently react with materials such as a water or steam. When a sodium–water reaction (SWR) occurs due to leakage or breakage of steam generator tubes, high-pressure waves and corrosive reaction products are produced, which threaten the structural integrity of the components of the intermediate heat-transfer system (IHTS) and the safety of the primary heat-transfer system (PHTS). In the PGSFR, SWR events are included in the design-basis event. This event should be analyzed from the viewpoint of the integrities of the IHTS and fuel rods. To evaluate the integrity of the IHTS based on the consequences of the SWR, the behaviors of the generated high-pressure waves are analyzed at the major positions of a failed IHTS loop using a sodium–water advanced analysis method-II code. The integrity of the fuel rods must be consistently maintained below the safety acceptance criteria to avoid the consequences of the SWR. The integrity of the PHTS is evaluated using the multidimensional analysis of reactor safety-liquid metal reactor code to model the whole plant.

Polydiacetylene (PDA)/poly (vinyl alcohol) (PVA) hybrid films are investigated for detection of ammonia gas generated by the food spoilage process. The films were obtained by mixing solutions containing diacetylene vesicles and aqueous PVA, and then drying. The films, which consist of carboxylic-acid-terminated PDA, showed a blue-to-red color transition upon reaction with ammonia gas. Through Fourier transform infrared (FTIR) analysis, we found that the observed color transition resulted from an ionic interaction between the carboxyl group of PDA and ammonia gas. In addition, patterned films were fabricated by selective UV irradiation through a photomask. Finally, the PDA/PVA hybrid films were found to show a color transition after reaction with real proteinic food at 25 °C. These results verify that the PDA/PVA hybrid films can be used for easier and more convenient real- time detection of food spoilage by the naked eye.

Polydiacetylene nanowires composed of 10, 12-docosadiynedioic acid (DCDDA) were fabricated simply by solution reprecipitation method with diameter of 50–150 nm and length of several micrometers. As the DCDDA nanowires are exposed to aqueous solutions of pH less than 7, there is no fluorescence emission observed. In contrast, we observed the a red-fluoresce response of the nanowires as they exposed to solutions of pH ranging 8–10, reflecting the degree of ionization of carboxylate head groups.

A novel protein recognition platform is developed using aptamer-linked polythiophene nanowires. As the aptamer functionalized poly (3-methylthiophene) nanowire is treated by the specific protein, resonance Raman and photoluminescence signals are simultaneously enhanced. Statistical analyses deliver the capability of a single conjugated polymer nanowire with phase-transition characteristics in response to selectivity and concentration.

π-Conjugated polymers have become qualified candidates for biosensing owing to their unique optoelectronic properties and excellent biocompatibility. In this contribution, nucleotide mismatches in DNA hybridization, being variable in position, are reflected in a stark manner by poly(3-methylthiophene) (P3MT) nanowires (NWs), in which probe DNA sequence is properly functionalized. Selected as the systematic investigation are complementary target DNA (tDNA), random sequence DNA, and three kinds of 1-mer mismatched tDNAs with different mismatch loci away from the NW's surface. Nanoscale optical observation of the single P3MT NWs in solid states reveals that the more distant the mismatch position is from the surface, the higher the photoluminescence (PL) occurs, while the complementary sequence yields the highest but the random one remains the lowest. Hence, the PL intensity increases with the relative length of the DNA-DNA hybridization from the surface. These results deliver a new basis that π-conjugated polymers can be potentially applicable to detailed nucleotide analyses as in single nucleotide polymorphism.

In this study, silicon nitride (SiNx) thin films were deposited by inductively coupled plasma chemical vapor deposition using trisilylamine (TSA, N(SiH3)3) and ammonia (NH3) plasma, and their moisture barrier properties were improved by plasma post-treatment. Ar, N2, and O2 plasmas were applied to the SiNx films after deposition. After O2 plasma treatment, the reduction of hydrogen in -NHx was confirmed by FT-IR analysis. Mass spectroscopic results showed a distinct hydrogen peak in the O2 plasma processes. Hydrogen was speculated to be removed from the SiNx surface, and the reduced hydrogen on the surface was attributed to the densification of the SiNx thin films. The increased film density reduced the moisture permeability of the SiNx thin films. The water vapor transmission rate (WVTR) of 120-nm thick single SiNx thin films was reduced by 77% to 3.0 × 10−3 g/m2-day from 1.3 × 10−2 g/m2-day with O2 plasma treatment. The increase of WVTR evaluated using a bending test was adopted to estimate flexibility. The increase of WVTR reduced to 71% in O2-plasma treated SiNx single layers from 88% with untreated SiNx single layers after bending the film at a bending radius of 1.5 cm. Multilayer moisture barrier films were fabricated using the O2-plasma treated SiNx layers and hydrocarbon plasma polymer layers made of cyclohexane plasma to further improve the moisture barrier properties and flexibility. The increase of WVTR reduced by approximately five times in the multilayer structure with O2 plasma treated SiNx/hydrocarbon plasma polymer after the bending test. A WVTR of 7.6 × 10−4 g/m2-day was obtained with an alternating nine-layer structure. In this study, we demonstrated that plasma post-treatment processes can improve the moisture barrier properties and flexibility by reducing the hydrogen dangling bonds and hydrogen concentration inside SiNx thin films.

DNA strands have been recently found to play a role in crystallizing organic semiconductors as a substitute for conventional surfactants. Such DNA-guided organic semiconductor particles possessed the recognition ability to complementary target DNAs, resulting in “enhanced luminescence” due to the lesser degree of non-radiative dissipation. Apart from this, in this study we developed selective recognition of mercury ions by utilizing DNA probes having ion-specific thymine-rich motifs. Strikingly, the specific ion–DNA interaction triggered rather distinctive “depressed luminescence” emitting from the particles. The mercury ions were found to be present both at the surface and the inner regions, which were discovered to relate to the drastic morphological distortion of the particles as evidenced by elemental, electron microscopy, and confocal fluorescence microscopy analyses. This novel phenomenon discovered would expand the technological values of organic semiconductors conjugated with oligonucleotides toward a wider range of target-specific applications.

Photocurable formulations containing trifunctional thiol, trifunctional ene, and antibacterial allylimidazolium salts have been employed for transparent antibacterial coatings. The antibacterial component 1-allyl-3-dodecylimidazolium salt (ADIm) is prepared and chemically attached to polymer networks using a one-step thiol–ene photocuring reaction. Ultra-small (USANS) and small angle neutron scattering (SANS) measurements show that the photocured polymers are loosely networked three-dimensional structures with a mass fractal of approximately 2.7 ± 0.2. The minimum inhibitory concentration (MIC) for the ADIm was determined to be 500 μg/ml and 15.63 μg/ml for Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) bacteria, respectively. Coating formulations containing 10 mol% of the antibacterial ADIm photocured on glass substrates showed strong antibacterial activity against environmental bacteria such as E. coli and/or S. aureus.

Immunochromatographic assay (ICA) using nitrocellulose (NC) membrane offers several advantages. This technique is a rapid and straightforward method in contrast to other immunoassays. Polydiacetylene (PDA) vesicles have unique optical properties to show red color and red fluorescence at the same time. In this system, red-phase PDA vesicles are used as a fluorescent dye as well as a surface for immobilized hepatitis B surface antibody (HBsAb). PDA has remarkable stability than other fluorescent dyes. In this study, the most suitable PDA/HBsAb complexes is introduced for detecting hepatitis B surface antigen (HBsAg). Then, the PDA/HBsAb complexes affixed antibody is attached to NC membrane, which has two lines to confirm detection of HBsAg. The main advantage of this system is that the detection of HBsAg can be observed in both visible and fluorescent images due to optical properties of polydiacetylene. Detection of HBsAg is observed up to 0.1 ng/ml by fluorescent analysis and confirmed red line on NC membrane up to 1 ng/ml (HBsAg) by the naked eye. Consequently, these results show that PDA/HBsAb complexes were successfully applied to ICA for the diagnosis of hepatitis B.

We report on the development of raspberry-like silica structures formed by the adsorption of 8-hydroxypyrene-1,3,6-trisulfonate (HPTS)@silica nanoparticles (NPs) on rhodamine B isothiocyanate (RBTIC)@silica NPs for ratiometric fluorescence-based pH sensing. To overcome the well-known problem of dye leaching which occurs during encapsulation of anionic HPTS dye in silica NPs, we utilized a polyelectrolyte-assisted incorporation of the anionic HPTS. The morphological and optical characterization of the as-synthesized dye-doped NPs and the resulting nanohybrids were carried out. The pH-sensitive dye, HPTS, incorporated in the HPTS-doped silica NPs provided a pH-dependent fluorescence response while the RBITC-doped silica provided the reference signal for ratiometric sensing. We evaluated the effectiveness of the nanohybrids for pH sensing; the ratio of the fluorescence emission intensity at 510 nm and 583 nm at excitation wavelengths of 454 nm and 555 nm, respectively. The results showed a dynamic response in the acidic pH range. With this approach, nanohybrids containing different dyes or receptors could be developed for multifunctioning and multiplexing applications.

Two kinds of magnesium hydroxide (Mg(OH)2) rods (Mg-Rod, 150 and 350 nm in size) and plates (Mg-PL, 60 and 300 nm) were prepared, and blended with poly(L-lactide) (PLLA) to obtain PLLA/Mg(OH)2 composites to investigate the effect of the shape and size of Mg(OH)2 particles. The structure, morphology, pH change, thermal and mechanical properties, cytotoxicity, and inflammation of Mg(OH)2 control and PLLA/Mg(OH)2 composites were evaluated. PLLA/Mg-Rod150 (30%) composite showed a 50% higher tensile strength and a 45% improved modulus as compared with PLLA/Mg-PL300 30% composite. Although Mg-Rods displayed similar cell viability (above 80%) as compared to Mg-PLs, the expression levels of TNF-α from Mg-PL60 gradually increased with increasing concentrations from 1 to 300 μg. This indicates that Mg-PL60 had a potential cytotoxicity due to endocytosis. In addition, the byproduct of PLLA/Mg-Rods composite was more effectively neutralized than that of the PLLA/Mg-PLs composite, but cell viability and the expression levels of TNF-α were similar. Therefore, the use of our PLLA/Mg-Rod composite system would be a promising strategy to prevent the current fatal problems in biomedical applications including biodegradable implants such as stents.

Biodegradable polymers such as poly(L-lactide) (PLLA) have been widely utilized as materials for biomedical applications. However, the relatively poor mechanical properties of PLLA and its acid-induced cell inflammation brought about by the acidic byproducts during biodegradation pose severe problems. In this study, these drawbacks of PLLA are addressed using a stereocomplex structure, where oligo-D-lactide-grafted magnesium hydroxide (MgO-ODLA) is synthesized by grafting d-lactide onto the surface of magnesium hydroxide, which is then blended with a PLLA film. The structure, morphology, pH change, thermal and mechanical properties, in-vitro cytotoxicity, and inflammation effect of the MgO-ODLAs and their PLLA composites are evaluated through various analyses. The PLLA/MgO70-ODLA30 (0-20 wt%) composite with a stereocomplex structure shows a 20% increase in its tensile strength and an improvement in the modulus compared to its oligo-L-lactide (PLLA/MgO70-OLLA30) counterpart. The interfacial interaction parameter of PLLA/MgO70-ODLA30 (5.459) has superior properties to those of PLLA/MgO70-OLLA30 (4.013) and PLLA/Mg(OH)2 (1.774). The cell cytotoxicity and acid-induced inflammatory response are suppressed by the neutralizing effect of the MgO-ODLAs. In addition, the inflammatory problem caused by the rapid acidification of the stereocomplex structure is also addressed. As a result, the stereocomplex structure of the MgO-ODLA/PLLA composite can be used to overcome the problems associated with the biomedical applications of PLLA films.

Purification is critical in any chemical process. The removal of impurities will produce the product in better quality and high standard. In this study, a new type of monomer was prepared by condensation polymerization of alkali lignin (AL) and methacryloyl chloride (MAC). The effect of AL/MAC ratio and the purification of MAC were investigated. The physical and chemical properties of the product obtained which is lignin methacrylate (LMA) were characterized by Fourier Transformed Infrared spectroscopy (FT-IR) and Nuclear Magnetic Resonance (1H-NMR). The result reveals that the purification was successfully removed the hydroxyl groups from the stabilizer in MAC and it is found that all the hydroxyl groups are coming from AL. The single interaction between AL and MAC has successfully enhanced the product obtain which does show no hydroxyl groups. The 1H-NMR data also showed that the purification of MAC influences the outcome. The noise and impurities were eliminated after the purification of MAC, and more pure products were obtained. This new monomer (LMA) synthesis that can be further utilized for various applications.

The aqueous-phase hydrodeoxygenation (APHDO) of 1-propanol at 230 °C and 35 bar was studied over 1 wt.% Pt catalysts supported on several metal oxides. Pt catalysts supported on amorphous silica, alumina and niobia aerogels, and crystalline niobic acid calcined at 500 °C showed low activities or deactivation. Under the APHDO condition, these supports experienced a structure transformation to crystalline quartz, boehmite and niobia TT phase. Pt/Nb 2 O 5 –Al 2 O 3 aerogel also suffered from the same crystallization behavior. In contrast, Pt/Nb 2 O 5 –SiO 2 aerogels with different Nb/(Nb + Si) ratios maintained a good catalytic performance for prolonged reaction periods. Through characterizations of spent catalysts, Nb 2 O 5 –SiO 2 aerogels were found to retain X-ray amorphous and porous structure. Also, their acid site densities were negligibly changed during the reaction. The catalysts with the Nb / (Nb + Si) ratio of 0.500 and 0.575 reached the molar propane/ethane ratio of about 1.0, indicating that Pt/Nb 2 O 5 –SiO 2 aerogel catalysts are highly active in the presence of water.

In the fructose dehydration to 5-hydroxymethylfurfural (HMF) in dimethyl sulfoxide, the catalytic function of 1,3-dialkylimidazolium-based ionic liquids with different counter-anions was investigated. It was found that the effects of alkyl chain length and additional alkyl group in Cl-containing ionic liquids were negligible whereas the activity of 1-butyl-3-methylimidazolium-based ionic liquids was considerably changed by varying the anion (particularly, halide ions). The latter finding was confirmed by the control experiment result that the addition of KBr or Ca(CH3COO)2 dramatically tuned the catalytic activity of 1-butyl-3-methylimidazolium chloride. From these results and the proposed reaction pathway, it was consequently believed that 1,3-dialkylimidazolium halide contained the dual catalytic function to act as both Bronsted acid and nucleophile for the fructose dehydration to HMF.

Many studies on polydiacetylene(PDA) have been investigated to apply to chemical and biological sensors due to their unique optical properties of color change from blue to red and fluorescence change from non-fluorescence to red fluorescence. Especially, high sensitivity against specific molecules is very important to apply polydiacetylenes to various sensors. In this study, we examined the effect of sensitivity enhancement of 10,12-pentacosadynoic acid(PCDA) vesicles in detection α-cyclodextrin(CD) according to control of vesicle size by filters with different pore sizes and poly- merization temperature. Colorimetric response(CR) was calculated using visible spectrometer. In order to investigate the effect of vesicle size on sensitivity of PDA vesicles, two PCDA vesicles were filtered without filtration and with 0.22 µm filter. The two PCDA vesicles were polymerized at 25 o C and were incubated with α-CD(5 mM) for 30 min. The CRs of the former and latter vesicles were 31.4% and 74.0%, respectively. Then, two PCDA vesicles filtered with 0.22 µm filter were polymerized at 25 o C and 5 o C and were reacted with α-CD(5 mM) for 30 min to examine the effect of polymerization temperature. The CRs of the former and latter vesicles were 74.0 and 99.2%, respectively. This sug- gests that vesicle sizes and polymerization temperature are key factors in enhancing the sensitivity of PDA vesicles. In addition, these results are expected to be useful to apply the PDA vesicles as biosensors to detect DNA, protein, and cells.

In this research, we developed a sensor system which can easily detect several chelating agents using polydiacetylene(PDA) vesicles. In comparison to other sensors, PDA based sensor has several advantages. First, detection method is much simpler and faster because it does not require any labeling step in the experiment procedure. Second, significant color-transition from blue to red based upon external stimulus allows us the detection by naked eyes. Finally, it is also possible to perform quantitative analysis of the concentration of the chelating agent by measuring the colorimetric response. In this paper, five types of chelating agents were used, including EDTA, EGTA, NTA, DCTA and DTPA. Among them, EDTA and DCTA triggered especially strong color-transition. In conclusion, this study has led to a successful development of a color transition-based PDA sensor system for easy and rapid detection of chelating agents.

In this work, silicon nitride (SiNx) films were deposited on plastic substrates at room temperature close to 30[Formula: see text]C on polyethylenenaphthalate (PEN) films in an inductively coupled plasma (ICP) reactor with trisilylamine (TSA, N(SiH[Formula: see text]) precursor and ammonia for flexible moisture barrier films. Moisture barrier property is improved as SiNx layer gets thicker, but cracks are found at thicker films above 300[Formula: see text]nm or more. And the barrier performance of the thicker layers is degraded significantly. In order to improve both flexibility and barrier property, plasma polymer (PP) layers were deposited at room temperature and introduced between the SiNx layers. The water vapor transmission rate (WVTR) of a single SiNx film, [Formula: see text][Formula: see text]g/(m[Formula: see text]), is reduced to [Formula: see text][Formula: see text]g/(m[Formula: see text]) with SiNx/PP/SiNx/PP/SiNx alternating five-layer structure. After 1000 times bending in 1.5[Formula: see text]cm of bending radius, the WVTR increases by 41% with five-layer structure, while that of single-layer structure increases by 69%. This work demonstrated that the SiNx and PP layers can be deposited at room temperature for flexible moisture barrier films.

Pt nanowires are prepared by treating electrospun polyvinyl pyrrolidone (PVP)–Pt composite fibers at high temperatures in an air atmosphere and their activities toward a methanol oxidation reaction (MOR) are investigated. Thermogravimetric analysis (TGA) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) results indicate that the electrospun PVP–Pt composite fibers thermally decompose at 250 °C, which leads to the removal of 98 wt% of the PVP polymer and the simultaneous reduction of the Pt precursor to a Pt nanowire. The physical and electrochemical properties of Pt nanowires are found to be affected by the heat treatment conditions such as heating rate, time, temperature, and atmosphere. Furthermore, polymer fibers subjected to a pyrolization process in nitrogen followed by exposure to an air atmosphere enhance the surface area of the Pt nanowires, leading to high electrochemical activity toward a MOR. The detailed physical and electrochemical properties of the Pt nanowires are characterized by various spectroscopic and electrochemical techniques, and the possibilities of using them as electrocatalysts in a fuel cell are explored.

Isolated carbon microspheres in a diameter range of 1–4 μm were prepared by hydrothermal treatment of mono-saccharides (xylose for pentose and fructose for hexose) with phenolic compounds–phenol, resorcinol, and phloroglucinol. It was found that addition of these compounds, particularly phloroglucinol, into a sugar solution led to a substantial increase (roughly 20-fold) of the carbon yield. Mono-saccharides are dehydrated into furan compounds during hydrothermal carbonization, and these compounds subsequently react with phloroglucinol, as revealed by examination of high-performance liquid chromatograms. Through elemental analysis and spectroscopic studies, it was found that several oxygen functionalities including hydroxyl, carbonyl, carboxyl, ether, quinone, and ester groups were located throughout the carbon spheres derived from sugars and phloroglucinol. On the basis of the carbon formation mechanism, the C–O–C bond formed by linkage of OH groups of phenolic compounds preferentially exists at the core of carbon spheres whereas the outer carbon surface contains reactive oxygen functionalities such as hydroxyl, carbonyl, carboxylic, and ester groups, corresponding with results obtained with sugar-derived carbon materials.

Thin CdS films were fabricated by Langmuir deposition, self-assembly, and dip-pen nanolithography methods. Firstly, LB films of saturated arachidic acid and LS films of unsaturated 10,12-pentacosadiynoic acid were reacted with cadmium ions and exposed to H2S gas. Formation of CdS crystal was observed with Fourier transform infrared (FTIR) spectra and atomic force microscope (AFM). Secondly, mercaptohexadecanoic acid was self-assembled on Au sub- strate and was reacted with CdS colloidal particles. At pH=9.1, the density of CdS colloids immobilized on Au sub- strate was very high compared to one at pH=5.0. Finally, thin films of CdS were also prepared on silicon and Au sub- strates by cadmium chloride-coated AFM tip and successive exposure of H2S gas. Localized formation of CdS crystal was suggested with AFM and depth-profiling Auger electron microscopy (AES).

Polydiacetylenes (PDAs), a family of highly π-conjugated polymers, have unique characteristics associated with their ability to self-assemble. Disruption of the extensively delocalized enyne backbones of molecularly ordered PDA sidechains induces a blue-to-red color change, which has been elegantly applied in the design of chemosensors. Recently, colorimetrically reversible PDAs have received significant attention, not only to gain a better understanding of the fundamentals of PDA chromism, but also to develop methodologies to overcome limitations associated with their colorimetrically irreversible counterparts. In this article, recent progress made in the field of colorimetrically tunable (reversible, stable, or sensitive) PDAs is described. Major emphasis is given to rational design strategies developed in our group. Relevant mechanistic investigations, a diagnostic method to test colorimetric reversibility, as well as future challenges in this area will be also discussed.