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

We describe the development of multifunctional nanoparticle probes based on semiconductor quantum dots (QDs) for cancer targeting and imaging in living animals. The structural design involves encapsulating luminescent QDs with an ABC triblock copolymer and linking this amphiphilic polymer to tumor-targeting ligands and drug-delivery functionalities. In vivo targeting studies of human prostate cancer growing in nude mice indicate that the QD probes accumulate at tumors both by the enhanced permeability and retention of tumor sites and by antibody binding to cancer-specific cell surface biomarkers. Using both subcutaneous injection of QD-tagged cancer cells and systemic injection of multifunctional QD probes, we have achieved sensitive and multicolor fluorescence imaging of cancer cells under in vivo conditions. We have also integrated a whole-body macro-illumination system with wavelength-resolved spectral imaging for efficient background removal and precise delineation of weak spectral signatures. These results raise new possibilities for ultrasensitive and multiplexed imaging of molecular targets in vivo.

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In vivo cancer targeting and imaging with semiconductor quantum dots

1. Introduction 2. Theoretical foundations 3. Propagation and focusing of optical fields 4. Spatial resolution and position accuracy 5. Nanoscale optical microscopy 6. Near-field optical probes 7. Probe-sample distance control 8. Light emission and optical interaction in nanoscale environments 9. Quantum emitters 10. Dipole emission near planar interfaces 11. Photonic crystals and resonators 12. Surface plasmons 13. Forces in confined fields 14. Fluctuation-induced phenomena 15. Theoretical methods in nano-optics Appendices Index.

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Principles of nano-optics

Wetting phenomena are ubiquitous in nature and technology. A solid substrate exposed to the environment is almost invariably covered by a layer of fluid material. In this review, the surface forces that lead to wetting are considered, and the equilibrium surface coverage of a substrate in contact with a drop of liquid. Depending on the nature of the surface forces involved, different scenarios for wetting phase transitions are possible; recent progress allows us to relate the critical exponents directly to the nature of the surface forces which lead to the different wetting scenarios. Thermal fluctuation effects, which can be greatly enhanced for wetting of geometrically or chemically structured substrates, and are much stronger in colloidal suspensions, modify the adsorption singularities. Macroscopic descriptions and microscopic theories have been developed to understand and predict wetting behavior relevant to microfluidics and nanofluidics applications. Then the dynamics of wetting is examined. A drop, placed on a substrate which it wets, spreads out to form a film. Conversely, a nonwetted substrate previously covered by a film dewets upon an appropriate change of system parameters. The hydrodynamics of both wetting and dewetting is influenced by the presence of the three-phase contact line separating "wet" regions from those that are either dry or covered by a microscopic film only. Recent theoretical, experimental, and numerical progress in the description of moving contact line dynamics are reviewed, and its relation to the thermodynamics of wetting is explored. In addition, recent progress on rough surfaces is surveyed. The anchoring of contact lines and contact angle hysteresis are explored resulting from surface inhomogeneities. Further, new ways to mold wetting characteristics according to technological constraints are discussed, for example, the use of patterned surfaces, surfactants, or complex fluids.

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Wetting and Spreading

The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.

Synthetic molecular motors and mechanical machines.

The domain structure in thin films of an immiscible polystyrene/poly(methyl methacrylate) (PS/PMMA) blend was studied after spin-casting from a common solvent. Atomic force microscopy (AFM) combined with selective dissolution was used to obtain three-dimensional information on the domain morphology in thin films. Three different common solvents and three different substrate surfaces were studied. Distinct differences in the thin film domain structure and surface topography are observed depending on the substrate surface energy and the solubility of the two polymers in the three solvents. The topographic modulation can be explained by a different rate of solvent evaporation during spin-coating for the two phases. The normal and lateral organization of the phase-separated domains is governed by a complex interplay between preferential aggregation of one phase at the substrate and phase segregation in the film. Additionally, some of the results suggest that a dewetting process may be involved in the domain f...

Structure formation via polymer demixing in spin-cast films

Phase separation in bulk mixtures commonly leads to an isotropic, disordered morphology of the coexisting phases1. The presence of a surface can significantly alter the phase-separation process, however2,3. Here we show that the domains of a phase-separating mixture of polymers in a thin film can be guided into arbitrary structures by a surface with a prepatterned variation of surface energies. Such a pattern can be imposed on a surface by using printing methods for depositing microstructured molecular films4, thereby allowing for such patterns to be readily transferred to a two-component polymer film. This approach might provide a simple means for fabricating polymer-based microelectronic circuits5 or polymer resists for lithographic semiconductor processing.

Surface-induced structure formation of polymer blends on patterned substrates

We have experimentally determined a phase diagram for cylinder-forming polystyrene-block-polybutadien-block-polystyrene triblock copolymer in thin films. The phase behavior can be modeled in great detail by dynamic density functional theory. Deviations from the bulk structure, such as wetting layer, perforated lamella, and lamella, are identified as surface reconstructions. Their stability regions are determined by an interplay between surface fields and confinement effects.

Phase behavior in thin films of cylinder-forming block copolymers.

Wetting at polymer surfaces and interfaces

Atom transfer radical polymerization (ATRP) was applied to the synthesis of amphiphilic cylindrical polymer brushes by using the “grafting from” technique The procedure included the following steps:  (1) ATRP of 2-hydroxyethyl methacrylate (HEMA) gave well-defined poly(HEMA), (2) subsequent esterification of the pendant hydroxy groups of poly(HEMA) with 2-bromoisobutyryl bromide yielded a polyinitiator, poly(2-(2-bromoisobutyryloxy)ethyl methacrylate (PBIEM), (3) ATRP of various monomers (tert-butyl acrylate, or styrene) using PBIEM as polyinitiator yielded cylindrical brushes with homopolymer side chains, (4) addition of a second monomer (styrene or tert-butyl acrylate) formed the cylindrical brushes with diblock copolymer side chains (core−shell cylinders), and (5) hydrolysis of the poly(tert-butyl acrylate) (PtBA) block of the side chains to poly(acrylic acid) (PAA) formed amphiphilic core−shell polymer brushes By using this technique, well-defined core−shell cylindrical polymer brushes with polystyr

Georg Krausch

Papers

Structure formation via polymer demixing in spin-cast films

Surface-induced structure formation of polymer blends on patterned substrates

Phase behavior in thin films of cylinder-forming block copolymers.

Wetting at polymer surfaces and interfaces

Amphiphilic Cylindrical Core−Shell Brushes via a “Grafting From” Process Using ATRP