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Passive water penetration across the cell membrane by osmotic diffusion is essential for the homeostasis of cell volume, in addition to the protein-assisted active transportation of water. Since membrane components can regulate water permeability, controlling compositional variation during the volume regulatory process is a prerequisite for investigating the underlying mechanisms of water permeation and related membrane dynamics. However, the lack of a viable in vitro membrane platform in hypertonic solutions impedes advanced knowledge of cell volume regulation processes, especially cholesterol-enriched lipid domains called lipid rafts. By reconstituting the liquid-ordered (L

Hybrid nanostructures are promising for ultrasound-triggered drug delivery and treatment, called sonotheranostics. Structures based on plasmonic nanoparticles for photothermal-induced microbubble inflation for ultrasound imaging exist. However, they have limited therapeutic applications because of short microbubble lifetimes and limited contrast. Photochemistry-based sonotheranostics is an attractive alternative, but building near-infrared (NIR)-responsive echogenic nanostructures for deep tissue applications is challenging because photolysis requires high-energy (UV-visible) photons. Here, we report a photochemistry-based echogenic nanoparticle for in situ NIR-controlled ultrasound imaging and ultrasound-mediated drug delivery. Our nanoparticle has an upconversion nanoparticle core and an organic shell carrying gas generator molecules and drugs. The core converts low-energy NIR photons into ultraviolet emission for photolysis of the gas generator. Carbon dioxide gases generated in the tumor-penetrated nanoparticle inflate into microbubbles for sonotheranostics. Using different NIR laser power allows dual-modal upconversion luminescence planar imaging and cross-sectional ultrasonography. Low-frequency (10 MHz) ultrasound stimulated microbubble collapse, releasing drugs deep inside the tumor through cavitation-induced transport. We believe that the photoechogenic inflatable hierarchical nanostructure approach introduced here can have broad applications for image-guided multimodal theranostics.

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.

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.

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...

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.

The colorimetric reversibility of polydiacetylene supramolecules, derived from a variety of functionalized diacetylenic lipids, has been subjected to detailed investigation. In an earlier effort, it was shown that polydiacetylene vesicles prepared from PCDA-mBzA 1, bearing terminal m-carboxyphenylamido groups, display complete reversibility upon thermal stimulation [J. Am. Chem. Soc. 2003, 125, 8976]. The origin and nature of reversible thermochromism in these systems have been elucidated in-situ in the current studies by using polydiacetylene supramolecules, prepared from analogues of PCDA-mBzA 1. Issues related to the effects of (1) internal amide groups, (2) headgroup aromatic interactions, (3) lengths of the hydrophobic alkyl chains, and (4) terminal carboxylic groups on the colorimetric reversibility of the polydiacetylene supramolecules have been probed. The results demonstrate that well-developed hydrogen-bonding and aromatic interactions between headgroups are essential for complete recovery of th...

Monomeric sialyl Lewis(X) (sLe(x)) and sLe(x)-like oligosaccharides are minimal structures capable of supporting selectin binding in vitro. However, their weak binding interactions do not correlate with the high-affinity binding interactions witnessed in vivo. The polyvalent display of carbohydrate groups found on cell surface glycoprotein structures may contribute to the enhanced binding strength of selectin-mediated adhesion. Detailed biochemical analyses of physiological selectin ligands have revealed a complicated composition of molecules that bind to the selectins in vivo and suggest that there are other requirements for tight binding beyond simple carbohydrate multimerization. In an effort to mimic the high-affinity binding, polyvalent scaffolds that contain multicomponent displays of selectin-binding ligands have been synthesized. Here, we demonstrate that the presentation of additional anionic functional groups in the form of sulfate esters, on a polymerized liposome surface containing a multimeric array of sLe(x)-like oligosaccharides, generates a highly potent, bifunctional macromolecular assembly. This assembly inhibits L-, E-, and P-selectin binding to GlyCAM-1, a physiological ligand better than sLe(x)-like liposomes without additional anionic charge. These multivalent arrays are 4 orders of magnitude better than the monovalent carbohydrate. Liposomes displaying 3'-sulfo Lewis(X)-like oligosaccharides, on the other hand, show slight loss of binding with introduction of additional anionic functional groups for E- and P-selectin and negligible change for L-selectin. The ability to rapidly and systematically vary the composition of these assemblies is a distinguishing feature of this methodology and may be applied to the study of other systems where composite binding determinants are important for high-affinity binding.

Polymerized thin films based on polydiacetylenes (PDAs) undergo distinct color transitions that lend themselves to applications in biosensing, surface modification, nonlinear optics, and molecular electronics. The mechanism of the thermochromic blue to red color transition of PDA thin films was investigated at the molecular level using atomic force microscopy and at the macroscopic level with visible absorption and Fourier transform infrared spectroscopy. The thermochromic transition temperature is found to be between 70 and 90 °C. At the molecular level, the ordering of the film increases at the thermochromic transition and remains ordered up to temperatures well above the transition (e.g., 130 °C). No evidence for previously suggested entanglement or disordering of the alkyl side chains is observed. The pendant side chains rearrange from a partially disordered configuration characteristic of the blue film,to a well-ordered close-packed hexagonal arrangement in the red form. The rearrangment of the pendant side chains is linked to the formation of the red phase PDA.

Simple and general differential criteria are derived for testing equilibrium adsorption isotherms for consistency with the laws of thermodynamics. The generalized Langmuir isotherm (L-model) for binary solutes of different sizes or adsorption capacities fails the test, as previously noted. A consistent isotherm is derived for the first time, by using the framework of the ideal adsorbed solution (IAS) theory of Myers and Prausnitz (AIChE J. 1965, 11, 121). The scaled particle theory isotherms for circular disks are shown to be thermodynamically consistent and to lead to almost identical predictions as an IAS model based on a modified Langmuir isotherm. All models with ideal mixing in the adsorbed solution predict that at high coverages the larger molecules (those with smaller adsorption capacity) are substantially depleted from the surface for steric and entropic reasons. With increasing concentration, the models predict selectivity reversals in cases where the larger molecules are not much more surface active than the smaller molecules.

36O and 42O, respectively. Those angles of the transition moments of the CHI group were 66O and 46O, respectively. Cadmium and lead stearate monolayers had nearly uniaxial chain and moment distributions. Molecular orientations varied substantially with the ion type bound to the polar groups but little with the substrate surface. The average tilt angle of the chain axes was ca. 1 1 O higher in X-type monolayers (methyl groups on the substrate surface) than in Z-type monolayers (polar groups on the surface) of lead stearate. The dichroic ratio for the cadmium stearate monolayer decreased from 0.98 at 25 OC to 0.84 at 130 OC. Recrystallization of the monolayer upon cooling was observed to be reversible and showed no time lag.

Self-assembled diacetylene vesicles were spotted and immobilized on aldehyde-modified glass substrates using conventional microarray technology. Irradiation of the immobilized diacetylenes allowed generation of nonfluorescent "blue-phase" polydiacetylene (PDA) arrays. Specific interaction of the PDA vesicle arrays with carbohydrates or poly(acrylic acid) solutions afforded fluorescent profiles.