Current status and future perspectives in atom transfer radical polymerization (ATRP) are presented. Special emphasis is placed on mechanistic understanding of ATRP, recent synthetic and process development, and new controlled polymer architectures enabled by ATRP. New hybrid materials based on organic/inorganic systems and natural/synthetic polymers are presented. Some current and forthcoming applications are described.

Atom Transfer Radical Polymerization (ATRP): Current Status and Future Perspectives

/pdf/nanoparticle-pegylation-for-imaging-and-therapy-45vkc0dds0.pdf

Nanoparticle PEGylation for imaging and therapy

An MCM-41 type mesoporous silica nanosphere-based (MSN) controlled-release delivery system has been synthesized and characterized using surface-derivatized cadmium sulfide (CdS) nanocrystals as chemically removable caps to encapsulate several pharmaceutical drug molecules and neurotransmitters inside the organically functionalized MSN mesoporous framework. We studied the stimuli-responsive release profiles of vancomycin- and adenosine triphosphate (ATP)-loaded MSN delivery systems by using disulfide bond-reducing molecules, such as dithiothreitol (DTT) and mercaptoethanol (ME), as release triggers. The biocompatibility and delivery efficiency of the MSN system with neuroglial cells (astrocytes) in vitro were demonstrated. In contrast to many current delivery systems, the molecules of interest were encapsulated inside the porous framework of the MSN not by adsorption or sol−gel types of entrapment but by capping the openings of the mesoporous channels with size-defined CdS nanoparticles to physically block...

A mesoporous silica nanosphere-based carrier system with chemically removable CdS nanoparticle caps for stimuli-responsive controlled release of neurotransmitters and drug molecules.

Functional π-Gelators and Their Applications

Supramolecular Chirality in Self-Assembled Systems

Hydrogels are polymeric networks, capable of absorbing large amounts of water and biological fluids. They are insoluble due to the presence of chemical or physical cross-links between the constituents. Hydrogels are promising materials for use as injectable biomaterials due to their high water content, tunable viscoelasticity, and biocompatibility. Peptides and proteins are important building blocks in the design of hydrogels, since they are easily degraded by the body and display a high biocompatibility. This review aims to give an overview of hydrogels in which peptides and proteins are structural elements of the polymer network. The review starts with hydrogels derived from naturally occurring structural proteins, followed by all-protein and peptide-based synthetic systems. Next, hybrid hydrogels composed of synthetic polymeric and peptide structural elements will be discussed. The potential of these hydrogels is illustrated with applications that are mainly derived from the field of tissue engineering.

Peptide- and Protein-Based Hydrogels

In this tutorial review we give an introduction into the field of stimulus responsive peptide based materials illustrated by some recent and current developments. We have tried to categorize them according to the stimulus the materials are responsive to, being pH, temperature, metal ions, enzymes and light. Because we have focused on the structural changes that these stimuli effect we have further classified the topics according to the secondary structures that are involved. These changes in molecular structure in turn cause a change in the macroscopic properties of the material they constitute. It is believed that these materials, often referred to as smart materials, have a great potential being applicable in areas like drug delivery, tissue engineering and bio-sensors.

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Stimulus responsive peptide based materials.

Creating bioconjugates by combining polymers with peptides and proteins is an emerging multidisciplinary field of research that has enjoyed increased attention within the scientific community. This critical review provides an overview of the strategies employed for the construction of these materials and will highlight the underlying synthetic methods used. This review is therefore relevant for chemists, material scientists and chemical biologists facing the challenge of constructing polypeptide–polymer bioconjugates in a controlled fashion (269 references).

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Polypeptide – polymer bioconjugates

/pdf/peptide-based-amphiphiles-29709fp9bn.pdf

Peptide based amphiphiles.

www.MaterialsViews.com C O M M Oppositely Charged Gelatin Nanospheres as Building Blocks for Injectable and Biodegradable Gels U N IC A T Huanan Wang , Morten B. Hansen , Dennis W. P. M. Lowik , Jan C. M. van Hest , Yubao Li , John A. Jansen , and Sander C. G. Leeuwenburgh * IO N The emergence of regenerative medicine has led to a paradigm shift in the design of novel biomaterials, which are now increasingly considered as (bio)active scaffolds that induce tissue regeneration as opposed to the more traditional concept of passively accepted implant materials. [ 1 ] In order to present biological stimuli to the physiological environment and to trigger tissue repair, optimal integration of synthetic biomaterials within the surrounding tissue is of paramount importance. In that respect, hydrogels made from biodegradable polymers are ideal candidates, since they are generally biocompatible, biodegradable, and, in some cases, injectable. [ 2–4 ] In addition, polymeric hydrogels can act as a reservoir for sustained release of therapeutic and signaling agents. [ 4 ] Nevertheless, current gelbased materials exhibit a rather poor ability to present multiple signaling molecules at programmed time-points and release rates. Colloidal gels, on the other hand, have recently been identifi ed as a promising “bottom-up” strategy for the design of highly functional scaffolds by employing microor nanometer-scale particles as building blocks to assemble into shape-specifi c bulk materials. [ 5–13 ] To this end, interparticle interactions such as electrostatic forces, [ 14 ] magnetic forces, [ 14 ] hydrophobic interactions [ 15 ] and steric hindrance [ 16 ] can be exploited to induce selfassembly of microor nanoparticles into integrated scaffolds. By incorporation of bioactive agents (e.g., enzymes, growth factors and/or biomineral nanocrystals) into these particulate building blocks of variable biodegradability, injectable gels with micrometer-scale resolution and complexity can be formed. This new class of materials would offer virtually unlimited degree of freedom with respect to their capacity for programmed drug release of multiple biomolecules at predetermined release rates. Charged polymeric microor nanospheres are the most obvious building blocks for the design of such injectable and

Dennis W. P. M. Löwik

Papers

Peptide- and Protein-Based Hydrogels

Stimulus responsive peptide based materials.

Polypeptide – polymer bioconjugates

Peptide based amphiphiles.

Oppositely charged gelatin nanospheres as building blocks for injectable and biodegradable gels.