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

J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities.

J-aggregates: from serendipitous discovery to supramolecular engineering of functional dye materials.

Supramolecular Chirality in Self-Assembled Systems

In this review, we describe the recent advances in supramolecular helical assemblies formed from chiral and achiral small molecules, oligomers (foldamers), and helical and nonhelical polymers from the viewpoints of their formations with unique chiral phenomena, such as amplification of chirality during the dynamic helically assembled processes, properties, and specific functionalities, some of which have not been observed in or achieved by biological systems. In addition, a brief historical overview of the helical assemblies of small molecules and remarkable progress in the synthesis of single-stranded and multistranded helical foldamers and polymers, their properties, structures, and functions, mainly since 2009, will also be described.

Supramolecular Helical Systems: Helical Assemblies of Small Molecules, Foldamers, and Polymers with Chiral Amplification and Their Functions

Chirality-Sensing Supramolecular Systems

Achiral diprotonated porphyrins, forming homoassociates in aqueous solution, lead to spontaneous chiral symmetry breaking. The unexpected result is that the chirality sign of these homoassociates can be selected by vortex motion during the aggregation process. This result is confirmed by means of circular dichroism spectra. These experimental findings are rationalized in terms of the asymmetric influence of macroscopic forces on bifurcation scenarios and by considering the specific binding characteristics of the porphyrin units to form the homoassociates.

http://science.sciencemag.org/content/sci/292/5524/2063.full.pdf

Chiral Sign Induction by Vortices During the Formation of Mesophases in Stirred Solutions

The title porphyrin shows non ideal cmc with formation of J-aggregates, due to the formation of intermolecularly stabilized zwitterions, which at high concentration also results in H-aggregates.

Aggregation in water solutions of tetrasodium diprotonated meso-tetrakis(4-sulfonatophenyl)porphyrin

Folding and hydrodynamic forces in J-aggregates of 5-phenyl-10,15,20-tris(4-sulfophenyl)porphyrin.

The aggregation in water of the free bases and the diprotonated forms of p-sulfonatophenyl and phenyl meso-substituted porphyrins [sodium salts of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3), 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2A), 5,15-bis(4-sulfonatophenyl)-10,20-diphenylporphyrin (TPPS2O), 5-(4-sulfonatophenyl)-10,15,20-diphenylporphyrin (TPPS1) and 5,15-bis(4-sulfonatophenyl)porphine (DPPS2O)] was studied by UV/Vis, 1H-NMR, fluorescence, polarized fluorescence and resonance light scattering. The presence of hydrophobic phenyl groups favours the aggregation. The free bases TPPS4 and TPPS3 aggregate into stacks of ill-defined geometry. TPPS2A and DPPS2O give H-aggregates. TPPS2O and TPPS1 give J-aggregates through interaction of the hydrophobic phenyl groups, that is their geometry corresponds to edge-to-edge arrangements. All these porphyrins give J-aggregates upon diprotonation, through electrostatic interactions between the positively charged porphyrin ring and the sulfonato group. These J-aggregates give different arrays depending on the meso-substitution pattern.

Self-assembly in water of the sodium salts of meso-sulfonatophenyl substituted porphyrins

There are few unambiguous reports describing the transfer of chirality from stirring vortices down to the level of electronic transitions. In this tutorial review the methods reported are discussed as well as the structural trends that seem to be necessary conditions in order to detect this phenomenon.

Joaquim Crusats

Papers

Chiral Sign Induction by Vortices During the Formation of Mesophases in Stirred Solutions

Aggregation in water solutions of tetrasodium diprotonated meso-tetrakis(4-sulfonatophenyl)porphyrin

Folding and hydrodynamic forces in J-aggregates of 5-phenyl-10,15,20-tris(4-sulfophenyl)porphyrin.

Self-assembly in water of the sodium salts of meso-sulfonatophenyl substituted porphyrins

Hydrodynamic effects on chiral induction.