Fabrication of magnetic force microscopy probes via localized electrochemical deposition of cobalt

Magnetic force microscopy probes were obtained via the solution phase electrochemical deposition of cobalt nanostructures at the probe apexes. Single tips were fabricated in an atomic force microscope fluid cell. Multiple tips were produced in a single batch with an alternating potential in an electrochemical cell. The probes achieve 50 nm spatial resolution

Evaluation of new materials for plasmonic imaging lithography at 476 nm using near field scanning optical microscopy

A new resist formulation was successfully patterned using near field optical microscopy in order to simulate the conditions prevailing in silver based plasmonic imaging tools. Radiation at 476 nm was transmitted through a near field scanning optical microscopy fiber probe tip to cross-link a film of poly(4-methacrylmethyl styrene) via polymerization of pendant methacryloyl groups using camphorquinone and dimethyl aniline as an initiating system. Patterns were generated by scanning at several speeds in order to moderate the dose while maintaining a constant probe height of about 5 nm above the sample through shear force feedback. After development, lines corresponding to the exposed regions were observed. At a scanning speed of 4 µm/s, the observed pattern has a full width at half maximum of 275 nm and a height of ~25 nm

Fabrication of magnetic force microscopy probes via localized electrochemical deposition of cobalt

Magnetic force microscopy probes were obtained via the solution phase electrochemical deposition of cobalt nanostructures at the probe apexes. Single tips were fabricated in an atomic force microscope fluid cell. Multiple tips were produced in a single batch with an alternating potential in an electrochemical cell. The probes achieve 50 nm spatial resolution

Polyphosphonium Polymers for siRNA Delivery: An Efficient and Nontoxic Alternative to Polyammonium Carriers

A water-soluble polyphosphonium polymer was synthesized and directly compared with its ammonium analog in terms of siRNA delivery. The triethylphosphonium polymer shows transfection efficiency up to 65% with 100% cell viability, whereas the best result obtained for the ammonium analog reaches only 25% transfection with 85% cell viability. Moreover, the nature of the alkyl substituents on the phosphonium cations is shown to have an important influence on the transfection efficiency and toxicity of the polyplexes. The present results show that the use of positively charged phosphonium groups is a worthy choice to achieve a good balance between toxicity and transfection efficiency in gene delivery systems

Small Molecule-Guided Thermoresponsive Supramolecular Assemblies

Small organic molecules with strong intermolecular interactions have a wide range of desirable optical and electronic properties and rich phase behaviors. Incorporating them into block copolymer (BCP)-based supramolecules opens new routes to generate functional responsive materials. Using oligothiophene-containing supramolecules, we present systematic studies of critical thermodynamic parameters and kinetic pathway that govern the coassemblies of BCP and strongly interacting small molecules. A number of potentially useful morphologies for optoelectronic materials, including a nanoscopic network of oligothiophene and nanoscopic crystalline lamellae, were obtained by varying the assembly pathway. Hierarchical coassemblies of oligothiophene and BCP, rather than macrophase separation, can be obtained. Crystallization of the oligothiophene not only induces chain stretching of the BCP block the oligothiophene is hydrogen bonded to but also changes the conformation of the other BCP coil block. This leads to an over 70% change in the BCP periodicity (e.g., from 31 to 53 nm) as the oligothiophene changes from a melt to a crystalline state, which provides access to a large BCP periodicity using fairly low molecular weight BCP. The present studies have demonstrated the experimental feasibility of generating thermoresponsive materials that convert heat into mechanical energy. Incorporating strongly interacting small molecules into BCP supramolecules effectively increases the BCP periodicity and may also open new opportunities to tailor their optical properties without the need for high molecular weight BCP