Obviously Enhanced Fluorescent Signal of Core-Shell Nanostructures through Simultaneous Regulation of Spectral Overlap and Shell Thickness for Imaging and Photothermal Therapy of Ovarian Cancer Cells

In this research, by simultaneously regulating the two major factors affecting the plasmonic enhanced fluorescence (PEF), spectral overlap and the distance between the fluororophores and the noble metal nanoparticles, a significantly enhanced fluorescent signal is achieved. Core-shell nanostructures composed of aspect ratio (AR) adjustable gold nanorods (GNRs) and various thickness of SiO₂ are prepared and the decorated fluorophores are realized optimized PEF. A typical stimuli-responsive conjugated polymer, polydiacetylene (PDA), and a near-infrared (NIR) dye Cy5.5 are selected as fluorophores and their fluorescent signal are enhanced 7.26 and 4.41 times, respectively. Based on the optimized optical properties, a multifunctional antibody modified Mab-Cy5.5-GNRs@SiO₂ is successfully demonstrated the targeting, imaging, and photothermal therapy (PTT) effects on SKOV-3 ovarian cancer cells.     

Synergetic Evolution of Diketopyrrolopyrrole‐Based Polymeric Semiconductor for High Reproducibility and Performance: Random Copolymerization of Similarly Shaped Building Blocks

A new random copolymer consisting of similarly shaped donor–acceptor building blocks of diketopyrrolopyrrole‐selenophene‐vinylene‐selenophene (DPP‐SVS) and DPP‐thiophene‐vinylene‐thiophene (DPP‐TVT) is designed and synthesized. The resulting P‐DPP‐SVS(5)‐TVT(5) with an equal molecular ratio of the two building blocks produced significantly enhanced solubility when compared to that of the two homopolymers, PDPP‐SVS and PDPP‐TVT. More importantly, despite the maximum segmental randomness of the PDPP‐SVS(5)‐TVT(5) copolymer, its crystalline perfectness and preferential orientation are outstanding, even similar to those of the homopolymers thanks to the similarity of the two building blocks. This unique property produces a high charge carrier mobility of 1.23 cm² V⁻¹ s⁻¹ of PDPP‐SVS(5)‐TVT(5), as determined from polymer field‐effect transistor (PFET) measurements. The high solubility of PDPP‐SVS(5)‐TVT(5) promotes formulation of high‐viscosity solutions which could be successfully processed to fabricate large‐areal PFETs onto hydrophobically treated 4 in. wafers. A total of 269 individual PFETs are fabricated. These devices exhibit extremely narrow device‐to‐device deviations without a single failure and demonstrate an average charge carrier mobility of 0.66 cm² V⁻¹ s⁻¹ with a standard deviation of 0.064. This is the first study to report on successfully realizing large‐areal reproducibility of high‐mobility polymeric semiconductors.

     

Quantification of a three-dimensional velocity vector using spectral-domain Doppler optical coherence tomography

Multiangle, fiber-based, spectral-domain Doppler optical coherence tomography with a phase-resolved algorithm is presented to measure three components of an arbitrary velocity vector. A beam divider that divides a probe beam to have five independent viewpoints and path length delays was designed. The divider was inserted into the sampling arm of a Doppler optical coherence tomography system between the collimator and the first galvo mirror of a two-axis galvo scanner. The divider produced five independent D k's (the average difference between the wave vectors of incoming and outgoing beams) after passing through the focusing lens while keeping two-axis scanning capability. After calibration, an unknown velocity vector field inside a microtube was quantified by solving a three-dimensional minimization problem.     

Object dependent sweep width reduction with spectral-spatial EPR imaging

For spectral-spatial EPR imaging, prior knowledge about the spatial support of an imaged object can be exploited in two ways. We can shrink the spatial field of view (FOV) to closely wrap the object in a sphere or reduce the sweep width in a projection dependent fashion. Use of a smaller spatial FOV with the same number of samples enhances spatial resolution by reducing voxel volume at the expense of signal-to-noise and a consequent degraded line-width resolution. We have developed another approach to define sweep width that prunes away the portions of the projection sweep with no signal. This reduces data acquisition time for the continuous wave (CW) EPR image proportional to the sweep width reduction. This method also avoids voxel volume reduction. Using the reduced-sweep method, we decreased the data acquisition time by 20% maintaining spatial and linewidth resolution.     

Diffusion of one or more components of a silane adhesion-promoting mixture into poly(methyl methacrylate)

The surface-sensitive technique of sum frequency generation (SFG) vibrational spectroscopy has been applied to study the buried interfaces between different polymers including deuterated polystyrene (d-PS) and deuterated poly(methyl methacrylate) (d-PMMA) and a two-component silane adhesion-promoting mixture (SAPM) composed of (3-glycidoxypropyl)trimethoxysilane (gamma-GPS) and a methylvinylsiloxanol (MVS). Because of the dissolution of d-PS, no SFG CH stretching signals could be collected from the d-PS/gamma-GPS interface, and SFG signals collected from the d-PS/SAPM interface gradually disappeared over time. SFG results also showed that gamma-GPS can diffuse through the d-PMMA film. The diffusion of gamma-GPS through the d-PMMA film was confirmed by SFG studies on the interface between gamma-GPS and a d-PMMA/PS two-polymer layer system. Initially the SFG signal from the PS layer was detected. However, after gamma-GPS diffused through the d-PMMA film, the PS film was dissolved by the silane, and thus the SFG signal from PS was lost. Similar experiments have been carried out at the interface between the SAPM and the d-PMMA/PS two-polymer layer system and it was found that the diffusion time of the gamma-GPS in the SAPM through the d-PMMA film was significantly longer. These results were much different to those from previous SFG studies on the analogous PET interfaces and appear consistent with differences in solubility parameters calculated for these systems.     

A highly conformationally specific alpha- and beta-Ala+ decarboxylation pathway

One-photon ionization of alanine and beta-alanine induces the decarboxylation reaction which occurs with the concomitant intramolecular hydrogen transfer in a highly conformationally specific manner.     

Functional regulation of hepatic cytochrome p450 enzymes by physicochemical properties of phospholipids in biological membranes

Knowledge regarding the regulation of hepatic cytochrome P450 (P450) is crucial to the fields of drug therapy and drug development, as well as to our understanding of the mechanisms underlying the metabolic activation of toxic and carcinogenic compounds. P450 is a membrane-anchored protein that shows a variety of interaction with membrane phospholipids, which affect the membrane topology and catalytic activities of the protein. In particular, anionic phospholipids, nonbilayer forming lipids, and the degree of saturation of the lipid fatty acyl chain play important roles in the functional regulation of P450, as well as in the bilayer structure of the membrane. However, despite the importance of phospholipids in the regulation of P450s, the interaction of the protein with membrane phospholipids, and the membrane properties induced by phospholipids which regulate P450, are unclear. In this review, we describe the effect of the physicochemical properties of the phospholipid constituents of biological membranes on hepatic P450 catalytic activity, membrane insertion (and/or penetration), and structural changes.     

Titanium K-edge absorption structure in Ti1−x NbxO2

The fine structure in the titanium x-ray K-edge absorption has been measured in Ti_1−x Nb_xO₂ mixed dioxides (x=0–0.1) with rutile structure in a laboratory-type spectrometer by total electron quantum-yield measurement. The position of the XANES lines is shown to be in good agreement with classical x-ray absorption spectra obtained in transmission. The structure and main features of the XANES spectra, including the effects of impurities and manyelectron excitations, are discussed. It is suggested that the intensity of the B peak characteristic of the titanium K edge depends on the Nb concentration and correlates with the charge state of titanium ions. Fiz. Tverd. Tela (St. Petersburg) 41, 894–896 (May 1999)