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

Complex chemical systems, such as living biological matter, are highly organized structures based on discrete molecules in constant dynamic interactions. These natural materials can evolve and adapt to their environment. By contrast, man-made materials exhibit simpler properties. In this Review, we highlight that most of the necessary elements for the development of more complex synthetic matter are available today. Using modern strategies, such as controlled radical polymerizations, supramolecular polymerizations or stepwise synthesis, polymers with precisely controlled molecular structures can be synthesized. Moreover, such tailored polymers can be folded or self-assembled into defined nanoscale morphologies. These self-organized macromolecular objects can be at thermal equilibrium or can be driven out of equilibrium. Recently, in the latter case, interesting dynamic materials have been developed. However, this is just a start, and more complex adaptive materials are anticipated. The polymer materials of the twenty-first century will be complex chemical systems that can respond and adapt to their environment. Such materials can be attained by synthesizing precision macromolecules with controlled architectures, and by mastering polymer interactions and self-organization.

From precision polymers to complex materials and systems

Being responsive and adaptive to external stimuli is an intrinsic feature characteristic of all living organisms and soft matter. Specifically, responsive polymers can exhibit reversible or irreversible changes in chemical structures and/or physical properties in response to a specific signal input such as pH, temperature, ionic strength, light irradiation, mechanical force, electric and magnetic fields, and analyte of interest (e.g., ions, bioactive molecules, etc.) or an integration of them. The past decade has evidenced tremendous growth in the fundamental research of responsive polymers, and accordingly, diverse applications in fields ranging from drug or gene nanocarriers, imaging, diagnostics, smart actuators, adaptive coatings, to self-healing materials have been explored and suggested. Among a variety of external stimuli that have been utilized for the design of novel responsive polymers, enzymes have recently emerged to be a promising triggering motif. Enzyme-catalyzed reactions are highly selective and efficient toward specific substrates under mild conditions. They are involved in all biological and metabolic processes, serving as the prime protagonists in the chemistry of living organisms at a molecular level. The integration of enzyme-catalyzed reactions with responsive polymers can further broaden the design flexibility and scope of applications by endowing the latter with enhanced triggering specificity and selectivity. In this tutorial review, we describe recent developments concerning enzyme-responsive polymeric assemblies, nanoparticles, and hydrogels by highlighting this research area with selected literature reports. Three different types of systems, namely, enzyme-triggered self-assembly and aggregation of synthetic polymers, enzyme-driven disintegration and structural reorganization of polymeric assemblies and nanoparticles, and enzyme-triggered sol-to-gel and gel-to-sol transitions, are described. Their promising applications in drug controlled release, biocatalysis, imaging, sensing, and diagnostics are also discussed.

Enzyme-responsive polymeric assemblies, nanoparticles and hydrogels

This review article presents the most recent developments in the use of materials based on dipyrromethene (DPM) and azadipyrromethenes (ADPM) for organic photovoltaic (OPV) applications. These chromophores and their corresponding BF2-chelated derivatives BODIPY and aza-BODIPY, respectively, are well known for fluorescence-based applications but are relatively new in the field of photovoltaic research. This review examines the variety of relevant designs, synthetic methodologies and photophysical studies related to materials that incorporate these porphyrinoid-related dyes in their architecture. The main idea is to inspire readers to explore new avenues in the design of next generation small-molecule and bulk-heterojunction solar cell (BHJSC) OPV materials based on DPM chromophores. The main concepts are briefly explained, along with the main challenges that are to be resolved in order to take full advantage of solar energy.

Design, synthesis and photophysical studies of dipyrromethene-based materials: insights into their applications in organic photovoltaic devices.

A fast, pH-responsive DNA hydrogel (see picture; right) was prepared by a three-armed DNA nanostructure (left) assembling together through the formation of intermolecular i-motif structures (middle). The hydrogel can be switched to the non-gel state in minutes by simply using environmental pH changes.

A pH-triggered, fast-responding DNA hydrogel.

In this study, DNA block copolymer (DBC) micelles with a polystyrene (PS) core and a single-stranded (ss) DNA shell were doped with ferrocene (Fc) molecules. Tapping mode atomic force microscopy (AFM) was used to study the morphology of the doped and undoped block copolymer aggregates. We show that introducing Fc molecules into the hydrophobic core does not affect the structural properties such as shape or size. In contrast, doping with Fc significantly changes the micelles' electrical properties, namely their polarizability. Electrostatic force microscopy (EFM) measurements reveal that the undoped micelles show no significant polarization signal, while the Fc-doped aggregates exhibit strongly enhanced polarizability. Furthermore, the nucleic acid moieties were utilized in combination with complementary ssDNA strands to assemble single particles into linear arrays of DBC nanoobjects. The ability to tune the electrostatic properties of the polymer core and the presence of nucleic acids might open the way for using these bioorganic nanoparticles as building blocks for nanoelectronic or biosensing devices.

/pdf/polarizability-of-dna-block-copolymer-nanoparticles-observed-2h5t1xk0g0.pdf

Polarizability of DNA block copolymer nanoparticles observed by electrostatic force microscopy.

The combination of synthetic polymers and DNA has provided biologists, chemists and materials scientists with a fascinating new hybrid material. The challenges in preparing these molecular chimeras were overcome by different synthetic strategies that rely on coupling the nucleic acid moiety and the organic polymer in solution or on solid supports. The morphologies and functions of the bioorganic block copolymers can be controlled by the nature of the synthetic polymer segment as well as by the sequence composition and length of the DNA. Recent developments have expanded the scope and applications of these hybrid materials in a number of different areas including biology and medicine, as well as bio- and nanotechnology. Their usage ranges from gene delivery through to DNA detection to programmable nano-containers for DNA-templated organic reactions.

/pdf/dna-meets-synthetic-polymers-highly-versatile-hybrid-3xbkzerkx9.pdf

DNA Meets Synthetic Polymers — Highly Versatile Hybrid Materials

Selective drug targeting of a specific organ or tissue is a challenging task. This holds especially true for chemotherapeutic cancer treatment because most of the available anticancer agents cannot distinguish between cancerous and healthy cells, leading to systemic toxicity and undesirable side effects. One effective approach to address this problem is the application of polymeric nanoparticles equipped with targeting units for tumor-specific delivery. [1] For instance dendrimers, highly branched macromolecules, can be equipped with targeting units as well as with anticancer drugs because of their large number of surface functionalities. [2] Amphiphilic block copolymers, which self-assemble in dilute aqueous solutions into three-dimensional spherical micelles with a hydrophilic corona and a hydrophobic core, are another attractive option. These nanosized objects, with a typical size of 10– 100 nm, are able to accommodate lipophilic drugs in their interior and alter their kinetics in vitro and in vivo. [3] Different polymeric systems such as shell crosslinked nanoparticles (SCKs), [4] poly(D,L-lactic-co-glycolic acid)-b-poly(ethylene glycol), [5] poly(ethylene glycol-b-e-caprolactone) [6] block copolymers and poly(N-isopropylacrylamide acrylic acid) microgels [7] have also been successfully utilized in combination with targeting units.

DNA Block Copolymer Micelles - ACombinatorial Tool for Cancer Nanotechnology**

Zielgerichtete Blockcopolymer-Mizellen

https://pure.rug.nl/ws/files/6758119/2011ChemCommAyazSupp.pdf

Synthesis of DNA block copolymers with extended nucleic acid segments by enzymatic ligation: cut and paste large hybrid architectures

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