Dominic C Chow

Department of Biomedical Engineering and Center for Biologically Inspired Materials and Material Systems Duke University Durham, North Carolina Engineering National Research Council National Institute for Nanotechnology and Department of Chemistry University of Alberta Edmonton, Alberta, Canada Kaplan Clinical Research Laboratory City of Hope Medical Center Duarte, California Department of Mechanical Engineering and Materials Science and Center for Biologically Inspired Materials and Material...

Preparation of Bimetallic Nanoparticles

Metallic nanoparticles of definite size are easily synthesized via a bottom-up approach and can be surface modified with special functional groups. Nanocomposites, i.e., alloy and core-shell particles are an attractive subject mainly because of their composition-dependent optical, magnetic, and catalytic properties. In general, bimetallic nanoparticles can be prepared by simultaneous reduction or by successive reduction of two metal ions through a suitable stabilization strategy (capping or...

Other Surface Functionalization Chemistries

In addition to the hydrosilylation and silanization routes described above, other surface functionaliza-tion chemistries have been investigated for attaching organic molecules to silicon surfaces. A few of them are briefly discussed here. Direct reaction of alcohols with both porous silicon 110 and silicon nanocrystals dispersed from porous silicon 111 has been reported to form Si-O-R linkages. Recently, surface functionalization of H-terminated silicon with alcohols using iodoform to iodinate...

Functionally Inspired Biomaterials 331 Introduction

We have discussed vesicles, peptoids, and PNAs as examples of biomimetic systems inspired by structures that nature created. We now turn to biomaterials inspired by biological functions. We are truly lucky to have a large biodiversity from which inspiration can be drawn for applications ranging from industry to medicine. Good examples can be found in the bioglues used by different organisms from mussels to geckos. Other living organisms such as limpets, snails, barnacles, and sea cucumber use...

Structure of PPVBased Systems

Based on molecular mechanics energy minimization in a vacuum, a single MEH-PPV or CN-PPV molecule containing tetrahedral defects has a lower total potential energy when folded into cofacial-stacked chain segments (see Figure 14.5) than in an extended chain configuration on the order of tens of kcal mol determined from the MM3 model for the all trans-anti-configuration. For MEH-PPV, an all trans-syn-configuration lies at 3 kcal mol higher in potential energy than the anti'-configuration due to...

New Generation of Nanotools

Nanotechnology has triggered a revolution in many important areas in molecular biology and medicine, especially in the detection and manipulation of biological species at the molecular and cellular levels. The convergence of nanotechnology, molecular biology, and medicine will open new possibilities for detecting and manipulating atoms and molecules using nanodevices, with the potential for a wide variety of medical applications at the cellular level. Today, the amount of research in biomedical...

Effect of MDR Expression on Drug Accumulation

Overexpression of MDR proteins is associated with the decreased intracellular accumulation and increased efflux of various chemotherapeutic drugs. Consequently, it is necessary for researchers to study and understand how the activity and distribution of the MDR proteins affects the accumulation and localization of therapeutic drugs. In our study, confocal microscopy and NSOM were used to monitor the effect of MDR protein, Pgp on the intracellular accumulation of MDR substrates, and...

Nucleoprotein Based Nanodevices in Drug Design and Delivery

Bionanotechnology for Molecular Targeting Assembly of Three-Address Nucleoprotein Arrays 7.2 Molecular 7.3 Oligodeoxynucleotide Cloning, Expression, and Purification of Fusion Proteins Y-Junction Device Assembly Applications of Ordered Arrays in Smart Drug Design Molecular Payloads

Bionanosciences The Art of Replicating the Structure and Function of Biological Systems

We understand that a living cell contains a number of reacting chemicals orchestrated by a complex network of feedback loops and sensing mechanisms, within a finite space that allows various forms of energy to transit across its boundaries. We also understand that the cell is a dynamic structure, self-replicating, energy dissipating, and adaptive. Yet, we have little idea on how to connect these two sets of characteristics How does life emerge from a system of chemical reactions It is accepted...

Dispersion from Porous Silicon

Soon after the first reports of visible PL from electrochemically etched porous silicon, Heinrich et al. 32 reported the preparation of luminescent colloidal suspensions of silicon particles by ultrasonic treatment of photoluminescent porous silicon. The porous silicon particles that resulted ranged in size from individual nanocrystals several nanometers in diameter to much larger porous structures many microns in size . Bley and coworkers subsequently improved and optimized the anodization...

Virosomes

A key issue in the development of second-generation vaccines involves targeting and delivery of antigens to antigen-presenting cells APCs . Remarkable advances have been achieved in vaccine preparation techniques and among them, virus-mimicking nanoparticles virosomes have demonstrated potency in eliciting immune responses while minimizing side effects. The term virosome was coined by Almeida et al. 44 in 1975 due to the unexpected finding of a viruslike structure during the visualization of...

Ab Initio and Semiempirical Quantum Chemistry

In order to eliminate any fundamental dependence on the assumed potential model, one must resort to the more complicated and time-consuming methods of quantum chemistry. Whereas clearly these techniques in theory provide the correct treatment of molecular and atomic systems, incomplete basis sets and limitations due to electron correlation or exchange for the methods capable of treating reasonably sized molecules can present considerable complications. In the present case, we are primarily...

Double Effective Medium Model for the Optical Properties

Various groups have tried, with mixed success, to explain the optical properties of thin films formed from organically cross-linked gold nanoparticles mainly for LBL films .20,28 The optical properties of the films can be described with a two-step EMA.33,39 Two steps are needed because three phases are present in the film the gold particles, the molecules, and voids, and because of the way they are distributed. The presence of the voids could be vaguely seen in previous SEM, scanning tunneling...

Comparison of 3D STEM with TEM Tomography for Biology

3D STEM is a 3D technique for the imaging of whole assemblies, as is tilt-series TEM, in contrast to the averaging techniques using diffraction from crystals or multiple images ofidentical objects. The resolution of the tomogram obtained in a tilt series both on cryo and embedded or stained is typically 5-10 nm in xyz 36-40 . From our calculations it follows that 3D STEM with the present microscopes already has approximately the same resolution 4 x 4 x 7 nm on a conventional thin section....

V

FIGURE 3.1 Structurally inspired biomaterials. Liposomes, virosomes, and polymersomes are examples of simple cell mimics without internal contents. They have been used for vaccines and targeted drug delivery systems. Peptide nucleic acids mimic both proteins and DNA, and peptoids are mimics of proteins. FIGURE 3.2 Functionally inspired biomaterials. Mussels and barnacles secrete proteinaceous bioglues for holdfasts on both organic and inorganic surfaces in aqueous environments....

H

Photoluminescent silicon nanocrystals, though most of them have not been demonstrated. Here, we briefly review biologically relevant examples of hydrosilylation, in roughly chronological order. In 1997, Wagner et al. 93 reported biofunctionalization of self-assembled monolayers SAMs of 1-octene formed by hydrosilylation of an H-terminated Si 111 surface. They used 254 nm UV-initiated hydrosilylation to form a dense monolayer of 1-octene on the wafer surface. They then used two different...

Mussel Adhesive Proteins

The harsh living conditions of the seashore, the impact of strong waves, and the buoyant force of water turn out to be selective forces in evolution. Only organisms that developed strategies for holding tightly to surfaces survived. The science of the mussel's strong adhesion was the subject of famous work done by Brown in 1952 90 , and later, Waite and Tanzer made a major breakthrough 91 . In their study, they found that MAPs in threads and plaques have extensive amount of posttranslationally...

Applications of Silicon Nanoparticles in Biophotonics

Actual applications of free silicon nanoparticles in biophotonics are still in their infancy. There are two recent reports in which silicon nanoparticles were surface functionalized to make them water dispersible and then used to image cells via fluorescence microscopy. Li and Ruckenstein 103 attached acrylic acid to red-emitting nanoparticles that had been produced by vapor-phase laser pyrolysis followed by solution-phase etching. They incubated fixed Chinese hamster ovary CHO cells with an...

Application of Bimetallics

The alteration in collective electronic, optical, and magnetic properties of organized nanoensembles for bimetallics over their monometallic counterpart is increasingly the subject of investigation 98 leaving catalytic applications aside 3,98-100 . It has the potential to be used as a nonlinear optical material. Possible future applications include the areas of ultrafast data communication and optical data storage 3-4,101 . Such materials would be useful in developing nanodevices e.g.,...