Iris S. Weitz

Electrochemical Characterization of Films of Single-Walled Carbon Nanotubes and Their Possible Application in Supercapacitors

Films of single-wall carbon nanotubes (SWCNTs) were cast from suspensions in several solvents on the surface of a Pt or Au electrode. Cyclic voltammetry of the films in MeCN did not show well-resolved waves (as distinct from films of C_(60) prepared in a similar manner). However, the increase in the effective capacitance of the electrode with a SWCNT film at 0.5 V vs. an AgQRE was 283 F/g, which is about twice that of carbon electrodes in nonaqueous solvents.

Copper oxide nanoparticles as contrast agents for MRI and ultrasound dual-modality imaging

Multimodal medical imaging is gaining increased popularity in the clinic. This stems from the fact that data acquired from different physical phenomena may provide complementary information resulting in a more comprehensive picture of the pathological state. In this context, nano-sized contrast agents may augment the potential sensitivity of each imaging modality and allow targeted visualization of physiological points of interest (e.g. tumours). In this study, 7 nm copper oxide nanoparticles (CuO NPs) were synthesized and characterized. Then, in vitro and phantom specimens containing CuO NPs ranging from 2.4 to 320 μg · mL(-1) were scanned, using both 9.4 T MRI and through-transmission ultrasonic imaging. The results show that the CuO NPs induce shortening of the magnetic T1 relaxation time on the one hand, and increase the speed of sound and ultrasonic attenuation coefficient on the other. Moreover, these visible changes are NP concentration-dependent. The change in the physical properties resulted in a substantial increase in the contrast-to-noise ratio (3.4-6.8 in ultrasound and 1.2-19.3 in MRI). In conclusion, CuO NPs are excellent candidates for MRI-ultrasound dual imaging contrast agents. They offer radiation-free high spatial resolution scans by MRI, and cost-effective high temporal resolution scans by ultrasound.

The application of C8K for organic synthesis: reduction of substituted naphthalenes

The reduction of disubstituted naphthalene derivatives by potassium–graphite intercalate C8K is reported. The reduction is carried out at 0 °C in tetrahydrofuran. The C8K–ether system suggests an alternative route for the Birch type reaction and the mechanism is discussed vis-a-vis the reaction in liquid ammonia.

1,2,5-Trisubstituted 1,4-diazepine-3-one: A novel dipeptidomimetic molecular scaffold

The continuing effort to transform bioactive peptides into non-peptide peptidomimetics of therapeutic potential requires a diversity of tools such as molecular scaffolds, pseudopeptide modifications, and conformation mimetics. To this end, a novel polyfunctional monoheterocyclic system, 1,2,5-trisubstituted hexahydro-3-oxo-1H-1,4-diazepine ring (DAP), was designed. The linear precursor for the DAP was generated through a reductive alkylation step including a modified side chain and an α-amino function of two amino acid derivatives. Structural analysis of model diastereomeric DAPs, employing1H and13C NMR and computer simulation, revealed the conformational preferences of this system. The structural similarities to the 1,4-benzodiazepine, a common molecular scaffold for many non-peptidic peptidomimetic agents, and the pronounced dipeptidomimetic character of the DAP system offer a new powerful tool to medicinal chemists engaged in rational peptide-based drug design.

Copper oxide loaded PLGA nanospheres: towards a multifunctional nanoscale platform for ultrasound-based imaging and therapy

Copper oxide nanoparticles (CuO-NPs) are increasingly becoming the subject of investigation exploring their potential use for diagnostic and therapeutic purposes. Recent work has demonstrated their anticancer potential, as well as contrast agent capabilities for magnetic resonance imaging (MRI) and through-transmission ultrasound. However, no capability of CuO-NPs has been demonstrated using conventional ultrasound systems, which, unlike the former, are widely deployed in the clinic. Furthermore, in spite of their potential as multifunctional nano-based materials for diagnosis and therapy, CuO-NPs have been delayed from further clinical application due to their inherent toxicity. Herein, we present the synthesis of a novel nanoscale system, composed of CuO-loaded PLGA nanospheres (CuO-PLGA-NS), and demonstrate its imaging detectability and augmented heating effect by therapeutic ultrasound. The CuO-PLGA-NS were prepared by a double emulsion (W/O/W) method with subsequent solvent evaporation. They were characterized as sphere-shaped, with size approximately 200 nm. Preliminary results showed that the viability of PANC-1, human pancreatic adenocarcinoma cells was not affected after 72 h exposure to CuO-PLGA-NS, implying that PLGA masks the toxic effects of CuO-NPs. A systematic ultrasound imaging evaluation of CuO-PLGA-NS, using a conventional system, was performed in vitro and ex vivo using poultry heart and liver, and also in vivo using mice, all yielding a significant contrast enhancement. In contrast to CuO-PLGA-NS, neither bare CuO-NPs nor blank PLGA-NS possess these unique advantageous ultrasonic properties. Furthermore, CuO-PLGA-NS accelerated ultrasound-induced temperature elevation by more than 4 °C within 2 min. The heating efficiency (cumulative equivalent minutes at 43 °C) was increased approximately six-fold, demonstrating the potential for improved ultrasound ablation. In conclusion, CuO-PLGA-NS constitute a versatile platform, potentially useful for combined imaging and therapeutic ultrasound-based procedures.

Target visualisation and microwave hyperthermia monitoring using nanoparticle-enhanced transmission ultrasound (NETUS)

Abstract Purpose: The aim of this study was to examine the feasibility of using nanoparticle-enhanced transmission ultrasound (NETUS) as an image-based monitoring modality for microwave hyperthermia treatment. Methods: A dedicated transmission ultrasound imaging system was used to obtain acoustic projections and ultrasound computed tomography images. Initially, speed-of-sound based images were used to non-invasively monitor temperature changes in in vitro and ex vivo specimens, induced by a microwave needle-type applicator. Next, the hyperthermia acceleration ability of two ultrasound nanoparticles based contrast agents (iron oxide and copper oxide) was examined and visualised. Finally, a two-step image guided microwave therapeutic procedure using NETUS was investigated in a realistic breast mimicking phantom. First, the pathology simulating region borders were detected. Then, a microwave-induced temperature elevation was non-invasively monitored. Results: The transmission ultrasound scanning system was able to detect temperature changes with a resolution of less than 0.5 °C, both in vitro and ex vivo. In accordance with previous studies, it was visually demonstrated that iron oxide nanoparticles expedite the heating process (p < 0.05). Copper oxide nanoparticles, however, did not alter the hyperthermia profile significantly. In the breast mimicking phantom, NETUS yielded accurate detection of the target region as well as thermal monitoring of the microwave heating procedure. Conclusions: NETUS can combine enhanced target visualisation with non-invasive thermometry and accelerated heating effect. Quantitative feedback, however, requires a tissue-specific calibration-curve. A proof of concept for microwave hyperthermia treatment monitoring using NETUS was established. The suggested methodology may potentially provide a non-invasive cost-effective means for monitoring thermal treatment of the breast.

Preliminary study of copper oxide nanoparticles acoustic and magnetic properties for medical imaging

The implementation of multimodal imaging in medicine is highly beneficial as different physical properties may provide complementary information, augmented detection ability, and diagnosis verification. Nanoparticles have been recently used as contrast agents for various imaging modalities. Their significant advantage over conventional large-scale contrast agents is the ability of detection at early stages of the disease, being less prone to obstacles on their path to the target region, and possible conjunction to therapeutics. Copper ions play essential role in human health. They are used as a cofactor for multiple key enzymes involved in various fundamental biochemistry processes. Extremely small size copper oxide nanoparticles (CuO-NPs) are readily soluble in water with high colloidal stability yielding high bioavailability. The goal of this study was to examine the magnetic and acoustic characteristics of CuO-NPs in order to evaluate their potential to serve as contrast imaging agent for both MRI and ultrasound. CuO-NPs 7nm in diameter were synthesized by hot solution method. The particles were scanned using a 9.4T MRI and demonstrated a concentration dependent T1 relaxation time shortening phenomenon. In addition, it was revealed that CuO-NPs can be detected using the ultrasonic B-scan imaging. Finally, speed of sound based ultrasonic computed tomography was applied and showed that CuO-NPs can be clearly imaged. In conclusion, the preliminary results obtained, positively indicate that CuO-NPs may be imaged by both MRI and ultrasound. The results motivate additional in-vivo studies, in which the clinical utility of fused images derived from both modalities for diagnosis improvement will be studied.

Conformational investigation of a novel dipeptide based molecular scaffold

The conformational features of a novel, dipeptide-based molecular scaffold are described. Four model systems of a trisubstituted 1,4-diazepine-3-one system, varying in the chirality and amino acid within the ring system, have been investigated by high-resolution NMR and metric-matrix distance geometry calculations. Because of the small number of protons within the scaffold, nuclear Overhauser effects provide only limited conformational information. Instead, extensive use of scalar1H−H1 and1H−13C coupling constants was utilized in the refinement. The resulting conformations of the model systems provide insigh into the expected topological orientation of the amino acids or chemical functionalities and attached to the seven-membered ring system, the first step of the utilization of this scaffold in the rational design of peptidomimetics.