Biomedical subjects

Pavel B Paramonov

Publications and source records attributed to Pavel B Paramonov.

3 recordsLinked to original sources

PubMed2006

Rearrangements in an alkylthiolate self-assembled monolayer using electrostatic interactions between nanoscale asperity and organomercaptan molecules.

Chemically induced rearrangements of amphifunctional molecules have been demonstrated using strong nonuniform electric fields (10(8)-10(10) V m(-1)) induced in the vicinity of nanoscale asperities. Electrostatic interactions utilizing these rearrangements of alkylthiolates assembled on Au(111) result in the nanopatterning of raised nanostructure (1.5-9 nm high, 15-100 nm wide) arrays on a second time scale by manipulating an atomic force microscope (AFM) tip above the monolayer. It is suspected that, as a result of the oxidative cleavage initiated by a weak bias of the tip, the S end of the alkylthiolate chain carrying a sulfenium cation is attracted to the (lifting) tip, forming bi- and higher-layer structures in the vicinity of the tip apex. Stabilization of the multiple-layered structures is accomplished via mutual attraction and entanglement of hydrocarbon chains. The rearrangements suggest a novel and general approach for nanoscale architecture in self-assembled systems.

Journal Article↗

PubMed2005

Density-functional description of water condensation in proximity of nanoscale asperity.

We apply nonlocal density-functional formalism to describe an equilibrium distribution of the waterlike fluid in the asymmetric nanoscale junction presenting an atomic force microscope tip dwelling above an arbitrary surface. The hydrogen bonding dominating in intermolecular attraction is modeled as a square-well potential with two adjustable parameters (energy and length) characterizing well's depth and width. A liquid meniscus formed inside the nanoscale junction is explicitly described for different humidity. Furthermore, we suggest a simple approach using polymolecular adsorption isotherms for the evaluation of an energetic parameter characterizing fluid (water) attraction to substrate. This model can be easily generalized for more complex geometries and effective intermolecular potentials. Our study establishes a framework for the density-functional description of fluid with orientational anisotropy induced by nonuniform external electric field.

Journal Article↗

PubMed2003

Electrostatic nanolithography in polymers using atomic force microscopy.

The past decade has witnessed an explosion of techniques used to pattern polymers on the nano (1-100 nm) and submicrometre (100-1,000 nm) scale, driven by the extensive versatility of polymers for diverse applications, such as molecular electronics, data storage, optoelectronics, displays, sacrificial templates and all forms of sensors. Conceptually, most of the patterning techniques, including microcontact printing (soft lithography), photolithography, electron-beam lithography, block-copolymer templating and dip-pen lithography, are based on the spatially selective removal or formation/deposition of polymer. Here, we demonstrate an alternative and novel lithography technique--electrostatic nanolithography using atomic force microscopy--that generates features by mass transport of polymer within an initially uniform, planar film without chemical crosslinking, substantial polymer degradation or ablation. The combination of localized softening of attolitres (10(2)-10(5) nm3) of polymer by Joule heating, extremely non-uniform electric field gradients to polarize and manipulate the soften polymer, and single-step process methodology using conventional atomic force microscopy (AFM) equipment, establishes a new paradigm for polymer nanolithography, allowing rapid (of the order of milliseconds) creation of raised (or depressed) features without external heating of a polymer film or AFM tip-film contact.

Microscopy, Atomic Force↗