抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

The discovery of carbon nanotubes has had a profound impact on many areas of science and technology, not least that of electroanalysis The properties and applications of carbon nanotubes themselves have been well reviewed in the literature and a number of reviews with an electrochemical emphasis have been published However, the modification of carbon nanotubes has recently been the focus of much research, primarily to improve their solubility in various solvents Yet modified carbon nanotube electrodes also allow the electrochemist to tailor the properties of the carbon nanotubes, or the electrode surface to impart desired properties such as enhanced sensing capabilities In this review we attempt to comprehensively cover the different chemical and electrochemical modification strategies and research carried out using modified carbon nanotubes for electroanalytical and bioanalytical applications Furthermore we also discuss the use of modified carbon nanotubes in electrocatalysis and biocatalysis from an analytical aspect, as well as seeking to dispel some of the myths surrounding the “electrocatalytic” properties of carbon nanotubes

Chemically Modified Carbon Nanotubes for Use in Electroanalysis

The development of atomic force microscopy (AFM) over the past 20 years has had a major impact on materials science, surface science and various areas of biology, and it is now a routine imaging tool for the structural characterization of surfaces. The lateral resolution in AFM is governed by the shape of the tip and the geometry of the apex at the end of the tip. Conventional microfabrication routes result in pyramid-shaped tips, and the radius of curvature at the apex is typically less than 10 nm. As well as producing smaller tips, AFM researchers want to develop tips that last longer, provide faithful representations of complex surface topographies, and are mechanically non-invasive. Carbon nanotubes have demonstrated considerable potential as AFM tips but they are still not widely adopted. This review traces the history of carbon nanotube tips for AFM, the applications of these tips and research to improve their performance.

Carbon nanotube tips for atomic force microscopy.

Entry into “[PhBP3]Fe” chemistry affords a rare, pseudotetrahedral iron(I) complex, [PhBP3]Fe(PPh3), with an S = 3/2 ground state. This precursor undergoes rapid oxidation by aryl azide to produce the d5 imide [PhBP3]Fe⋮NAr (Ar = p-tolyl). The Fe(III) imide is significant in that it is low-spin and represents the first mononuclear imide of iron. Doublet [PhBP3]Fe⋮NAr reacts rapidly and quantitatively with CO at room temperature to release isocyanate and [PhBP3]Fe(CO)2. The [PhBP3]Fe(CO)2 byproduct is also a precursor to [PhBP3]Fe⋮NAr upon addition of aryl azide.

A Low-Spin d5 Iron Imide: Nitrene Capture by Low-Coordinate Iron(I) Provides the 4-Coordinate Fe(III) Complex [PhB(CH2PPh2)3]Fe⋮N-p-tolyl

Scorpionates: genesis, milestones, prognosis

Scanning and transmission electron microscopy were used to image hundreds of single-wall carbon nanotube probes and to correlate probe morphology with AFM image resolution. Several methods for fabricating such probes were evaluated, resulting in a procedure that produces image-quality single-wall nanotube probes at a rate compatible with their routine use. Surprisingly, about one-third of the tips image with resolution better than the nanotube probe diameter and, in exceptional cases, with resolution better than 1 nm. This represents the highest lateral resolution reported to date for a SWNT probe.

/pdf/correlating-afm-probe-morphology-to-image-resolution-for-1eysgzrpx2.pdf

Correlating AFM Probe Morphology to Image Resolution for Single-Wall Carbon Nanotube Tips

A homoleptic phosphine adduct of Tl(I).

We have previously reported that 4−6 nm diameter single-wall carbon nanotube (SWNT) probes used for tapping-mode atomic force microscopy (AFM) can exhibit lateral resolution that is significantly better than the probe diameter when prone nanotubes are imaged on a flat SiO_2 surface. To further investigate this phenomenon, accurate models for use in atomistic molecular dynamics simulations were constructed on the basis of transmission electron microscopy (TEM) and AFM data. Probe−sample interaction potentials were generated by utilization of force fields derived from ab initio quantum mechanics calculations and material bulk and surface properties, and the resulting force curves were integrated numerically with the AFM cantilever equation of motion. The simulations demonstrate that, under the AFM imaging conditions employed, elastic deformations of both the probe and sample nanotubes result in a decrease of the apparent width of the sample. This behavior provides an explanation for the unexpected resolution improvement and illustrates some of the subtleties involved when imaging is performed with SWNT probes in place of conventional silicon probes. However, the generality of this phenomenon for other AFM imaging applications employing SWNT probes remains to be explored.

Influence of Elastic Deformation on Single-Wall Carbon Nanotube Atomic Force Microscopy Probe Resolution

Regulation of microtubule dynamics underlies many fundamental cellular mechanisms including cell division, cell motility, and transport. In neurons, microtubules play key roles in cell migration, axon outgrowth, control of axon and synapse growth, and the regulated transport of vesicles and structural components of synapses. Loss of synapse and axon integrity and disruption of axon transport characterize many neurodegenerative diseases. Recently, mutations that specifically alter the assembly or stability of microtubules have been found to directly cause neurodevelopmental defects or neurodegeneration in vertebrates. We report here the characterization of a missense mutation in the C-terminal domain of C. elegans alpha-tubulin, tba-1(ju89), that disrupts motor neuron synapse and axon development. Mutant ju89 animals exhibit reduction in the number and size of neuromuscular synapses, altered locomotion, and defects in axon extension. Although null mutations of tba-1 show a nearly wild-type pattern, similar axon outgrowth defects were observed in animals lacking the beta-tubulin TBB-2. Genetic analysis reveals that tba-1(ju89) affects synapse development independent of its role in axon outgrowth. tba-1(ju89) is an altered function allele that most likely perturbs interactions between TBA-1 and specific microtubule-associated proteins that control microtubule dynamics and transport of components needed for synapse and axon growth.

/pdf/motor-neuron-synapse-and-axon-defects-in-a-c-elegans-alpha-18ey67jrc2.pdf

Motor neuron synapse and axon defects in a C. elegans alpha-tubulin mutant.

A method for fabricating assembled structures. The method includes providing a tip structure, which has a first end, a second end, and a length defined between the first end and the second end. The second end is a free end. The method includes attaching a nano-sized structure along a portion of the length of the tip structure to extend a total length of the tip structure to include the length of the tip structure and a first length associated with the nano-sized structure. The method includes shortening the nano-sized structure from the first length to a second length. The method also includes pushing the nano-sized structure in a direction parallel to the second length to reduce the second length to a third length of the nano-sized structure along the direction parallel to the second length to cause the nano-sized structure to move along a portion of the length of the tip structure.

Ian R. Shapiro

Papers

Correlating AFM Probe Morphology to Image Resolution for Single-Wall Carbon Nanotube Tips

A homoleptic phosphine adduct of Tl(I).

Influence of Elastic Deformation on Single-Wall Carbon Nanotube Atomic Force Microscopy Probe Resolution

Motor neuron synapse and axon defects in a C. elegans alpha-tubulin mutant.

Method for manufacturing single wall carbon nanotube tips