Quantifying the Nanomachinery of the Nanoparticle–Biomolecule Interface

A study is presented of the nanomechanical phenomena experienced by nanoparticle‐conjugated biomolecules. A thermodynamic framework is developed to describe the binding of thrombin‐binding aptamer (TBA) to thrombin when the TBA is conjugated to nanorods. Binding results in nanorod aggregation (viz. directed self‐assembly), which is detectable by absorption spectroscopy. The analysis introduces the energy of aggregation, separating it into TBA–thrombin recognition and surface‐work contributions. Consequently, it is demonstrated that self‐assembly is driven by the interplay of surface work and thrombin‐TBA recognition. It is shown that the work at the surface is about ?10 kJ mol^?1 and results from the accumulation of in‐plane molecular forces of pN magnitude and with a lifetime of <1 s, which arises from TBA nanoscale rearrangements fuelled by thrombin‐directed nanorod aggregation. The obtained surface work can map aggregation regimes as a function of different nanoparticle surface conditions. Also, the thermodynamic treatment can be used to obtain quantitative information on surface effects impacting biomolecules on nanoparticle surfaces.     

Plasmonic Nickel Nanoantennas

The fundamental optical properties of pure nickel nanostructures are studied by far‐field extinction spectroscopy and optical near‐field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near‐field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near‐field and far‐field spectra, dramatic shifts are found between the near‐field and far‐field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping.     

Supramolecular Polymers: Rigid Dimers Formed through Strong Interdigitated H‐Bonds Yield Compact 1D Supramolecular Helical Polymers (Small 3/2011)

Hierarchical self‐assembly of small abiotic molecular modules interacting through noncovalent forces is increasingly being used to generate functional structures and materials for electronic, catalytic, and biomedical applications. The greatest control over the geometry in H‐bond supramolecular architectures, especially in H‐bonded supramolecular polymers, can be achieved by using conformationally rigid molecular modules undergoing self‐assembly through strong H‐bonds. Their binding strength depends on the multiplicity of the H‐bonds, the nature of donor/acceptor pairs and their secondary attractive/repulsive interactions. Here a functionalized molecular module is described, which is capable of self‐associating through self‐complementary H‐bonding patterns comprising four strong and two medium‐strength H‐bonds to form dimers. The self‐association of these phenylpyrimidine‐based dimers through directional H‐bonding between two lateral pyridin‐2(1H)‐one units of neighboring molecules allows the formation of highly compact 1D supramolecular polymers by self‐assembly on graphite. A concentration‐dependent study by scanning tunneling microscopy at the solid–liquid interface, corroborated by dispersion‐corrected density functional studies, reveals the controlled generation of either linear supramolecular 2D arrays, or long helical supramolecular polymers with a high shape persistence.     

Peculiar crystallization kinetics of biodegradable poly(lactic acid)/poly(propylene carbonate) blends

Binary blends of poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) were found to display a peculiar crystallization kinetics. The two biodegradable polymers were blended by melt mixing, to obtain binary blends at various compositions. Temperature‐modulated calorimetry and dynamic‐mechanical analysis indicated that the blend components are partially miscible, and display two separate glass transitions, at temperatures intermediate to those of the plain polymers. Electron microscopy analysis disclosed the morphology of PLA/PPC blends, made of PPC‐rich particles finely dispersed within the PLA‐rich matrix. The possible establishment of interactions between the functional groups of the two polymers upon melt mixing has been hypothesized as the reason for partial miscibility and compatibility of the two biodegradable polymers. The PLA/PPC blends display good mechanical properties, with enhanced performance at rupture compared with plain PLA. Most importantly, the addition of PPC affects also the crystallization kinetics of PLA, since the more mobile PPC chains favor diffusion of the stiffer PLA chain segments towards the growing crystals, which fastens the spherulite growth rate of PLA. Such positive influence of an amorphous polymer on crystal growth rate has been demonstrated here for the first time in blends that display phase‐separation in the melt. POLYM. ENG. SCI., 55:2698–2705, 2015. © 2015 Society of Plastics Engineers     

Usefulness of Photodynamic Therapy as a Possible Therapeutic Alternative in the Treatment of Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common cancer in individuals with fair skin type (I–II) and steadily increasing in incidence (70% of skin malignancy). It is locally invasive but metastasis is usually very rare, with an estimated incidence of 0.0028%–0.55%. Conventional therapy is surgery, especially for the H region of the face and infiltrative lesions; in case of inoperable tumors, radiotherapy is a valid option. Recently, topical photodynamic therapy (PDT) has become an effective treatment in the management of superficial and small nodular BCC. PDT is a minimally invasive procedure that involves the administration of a photo-sensibilizing agent followed by irradiation at a pre-defined wavelength; this determines the creation of reactive oxygen species that specifically destroy target cells. The only major side effect is pain, reported by some patients during the irradiation. The high cure rate and excellent cosmetic outcome requires considering this possibility for the management of patients with both sporadic and hereditary BCC. In this article, an extensive review of the recent literature was made, in order to clarify the role of PDT as a possible alternative therapeutic option in the treatment of BCC.     

基于古村落宅间元素模式的村落景观 设计优化策略——以徽州地区为例

新村空间设计语汇模块化是村落景观设计较为普遍的现象,也是地域特征弱化和空间不契合空间行为等问题的主要原因之一。古村落宅间元素是村民日常生活与村落环境在相互影响下长期适应性发展的结果,宅间元素模式研究可促进丰富新村空间设计语汇。以徽州地区古村落为例,从宅间元素的分类、图示、与空间行为的关联3个方面论述了古村落宅间元素模式研究方法论。通过徽州茆田新村景观设计阐述了宅间元素模式的应用,论述了基于古村落宅间元素模式的村落景观设计优化策略,有益于形成并推广地方空间设计语汇,避免过度依赖和使用既有的、来自城市的广场、草坪、树池等元素造成的全国村落的无差别设计。     

Water consumption during solid state sodium borohydride hydrolysis

In this paper nickel acetate catalyzed sodium borohydride cartridges have been prepared and hydrolyzed with water for hydrogen production. Two technological solutions have been tested to increase the overall hydrogen yield, namely a porous water diffuser and a hydrophobic membrane. The first was used to improve water diffusion inside the hydride while the second to confine water inside the cartridge. The generated hydrogen flow showed a very reproducible behavior. Hydrogen promptly evolved just after water was pumped into the cartridge. After some initial peaks, a constant hydrogen flow has been recorded for the whole reaction time. The constant flow was related to the presence of the porous diffuser. The use of a hydrophobic membrane to confine the water inside the cartridge allowed to increase the overall hydrogen yield: about 6 water molecules per mol of hydride were required to complete the reaction. The reaction product was identified by XRD as Na₂B₂O₄*8H₂O. The cartridge hydrogen gravimetric content, based on water and sodium borohydride weight, was as high as 4.64%.     

LAS glass–ceramic scaffolds by three-dimensional printing

Highly porous (>60% open porosity) glass–ceramic scaffolds with remarkable mechanical properties (compression strength of ～15 MPa) were produced by indirect 3D printing. Precursor glass powders were printed into 3D ordered structures and then heat treated to sinter and develop crystalline phases. The final glass–ceramic contained a β-spodumene solid solution together with a secondary phase of lithium disilicate.The precision of the printed geometry and the density of the struts in the scaffold depended on several processing parameters (e.g. powder size and flowability, layer thickness) and were improved by increasing the binder saturation and drying time. Two types of powders with different particle size distribution (PSD) and flowability were used. Powders with a larger PSD, could be processed within a wider range of printing parameters due to their good flowability; however, the printing precision and the struts density were lower compared to the scaffolds printed using the powder in a smaller average PSD.     

New Evidence for Cross Talk between Melatonin and Mitochondria Mediated by a Circadian-Compatible Interaction with Nitric Oxide

Extending our previous observations, we have shown on HaCat cells that melatonin, at ~10⁻⁹ M concentration, transiently raises not only the expression of the neuronal nitric oxide synthase (nNOS) mRNA, but also the nNOS protein synthesis and the nitric oxide oxidation products, nitrite and nitrate. Interestingly, from the cell bioenergetic point of view, the activated NO-related chemistry induces a mild decrease of the oxidative phosphorylation (OXPHOS) efficiency, paralleled by a depression of the mitochondrial membrane potential. The OXPHOS depression is apparently balanced by glycolysis. The mitochondrial effects described have been detected only at nanomolar concentration of melatonin and within a time window of a few hours’ incubation; both findings compatible with the melatonin circadian cycle.