Front Cover: Hydrogels and patterned substrates are increasingly used to study the influence of microenvironment on cell function. Here, we use E-Jet to pattern polyacrylamide with proteins as a rapid, flexible approach to creating platforms for studying cell behavior. The image depicts fibronectin ink droplets on a polyacrylamide substrate. Spot sizes as small as 5 μm can be printed and used to constrain single cells. Further details can be found in the article by M. J. Poellmann, K. L. Barton, S. Mishra, and A. J. Wagoner Johnson^* on page 1164. Image credit: Jeremy Miller, Ryan Durdle, and Alex Jerez of the ITG Visualization Lab.

Back Cover: Conjugates of a polycation and small molecular amphiphile can achieve efficient gene delivery by polymer-induced macromolecular transduction, which is independent of endocytosis and other energy-consum ption-dependent cellular uptake processes. The exposure of the small molecular amphiphiles on the surface of the polyelectrolyte complexes and the interactions of the exposed amphiphiles with the cell membrane may play an important role in the phenomenon. Further details can be found in the article by S. Y. Chae, H. J. Kim, M. S. Lee, Y. L. Jang, Y. Lee, S. H. Lee, K. Lee, S. H. Kim, H. T. Kim, S.-C. Chi, T. G. Park, and J. H. Jeong^* on page 1169.

Covalently immobilized growth factors are capable of stimulating cell behaviors that aid in tissue repair and regeneration, often eliciting a more pronounced cellular response than growth factor delivered in a soluble or adsorbed form. This Feature Article discusses strategies for immobilizing growth factors and applications of growth factor-modified materials in regenerative medicine.

Electrohydrodynamic jet (E-jet) printing is used to print proteins on soft, polyacrylamide substrates with micrometer-scale resolution. Immunofluorescence confirms the presence of patterned cell adhesion proteins, and the patterned hydrogels are shown to support cell attachment and spreading. The method can be used to create cell substrates with well-defined protein geometries and elastic properties.

Small-molecular amphiphile/polymer conjugates mediate internalization of plasmid DNA to mammalian cells without the aid of endocytosis or other energy-consuming processes, which mimics macromolecular transduction phenomenon by cell penetrating peptides. This novel modality of polymeric biomimetics can be applied to where cell penetrating peptides is required for enhanced delivery of macromolecules.

The degradation behaviour of novel poly(D,L-lactide)-block-poly(2-hydroxyethyl acrylate) (PLA-b-PHEA) block copolymer materials for nerve repair is investigated. In vitro and in vivo findings are very similar, and the PHEA block length has a strong impact on the degradation mechanism. Schwann cell adhesion on spin coated films of PLA-b-PHEA is assessed, and found to be improved compared to that obtained on PLA ones.

Native nanocellulose allows the deposition of few-atom fluorescent silver nanoclusters in a supramolecular manner mediated by poly(methacrylic acid). The polymer acts as protecting scaffold for the silver nanoclusters and interacts by hydrogen-bonding to cellulose nanofibers. The adducts show strong luminescence and significant antibacterial activity.

Cationic amphiphilic macromolecules can facilitate cellular siRNA delivery. Ethyleneimine-modified amphiphilic macromolecules that can encapsulate siRNA are synthesized. These polymers are less cytotoxic than linear polyethyleneimine above 10µM. The incorporation of nine amines into the unimer backbone produces a cationic polymer that can deliver siRNA to elicit gene silencing in malignant glioma cells.

A difunctional orthogonal coupler based on TMP is synthesized for the connection of a biological active carbohydrate on sP(EO-stat-PO) hydrogel-coated microtiter plates. This immobilization concept is proven by an ELLA of immobilized β-D-GlcNAc with biotinylated lectin II from Griffonia simplicifolia.

The fabrication of multilayer chitosan/methoxypoly(ethylene glycol)-block-poly(L-glutamic acid) films is reported. The mechanism of film growth is elucidated. It is demonstrated that cell adhesion is significantly reduced on surfaces coated with such multilayers, making them a promising coating material for many biomedical applications.

A simple and economical method is described for the heparinization of polysulfone membranes, aiming at preparing a low-density lipoprotein absorber for simultaneous LDL apheresis and hemodialysis. CA and TB colorimetric tests demonstrate improved hydrophilicity of the heparinized membranes, while EILSA tests show excellent LDL affinity.

Highly selective and unidirectional uptake/release of charged molecules through Pdop microcapsules can be achieved by controlling pH: at low pH, Pdop incorporates cationic dyes (rhodamine 6G); at high pH, Pdop prefers anionic dyes (methyl orange and alizarin red). The uptake from dye mixtures is highly selective.

The use of pyrene-functional polysulfone membranes as microwell assay platforms for oxidase and hydrolase/oxidase-based enzyme assays as well as cell detection is explored. Microwell plates covered with PSU-Py are applied for GOx and AG activity detection as well as for bioanalysis of glucose and AG inhibitors. A promising tool for cell detection is implemented.

An enhanced strategy for cell encapsulation with LbL shells is reported. By exploiting truly nonionic hydrogen-bonded shells without use of either synthetic or natural polyelectrolyte components, the viability of encapsulated cells increases from 20% in electrostatically-bonded membranes to 94% while long-term growth behavior is not affected.

Stable nanoassemblies are formed spontaneously by mixing host- and guest-modified dextrans bearing βCD and Ada groups, respectively. The strong interactions between the two polymers lead to nanoassemblies of tailorable sizes, depending on the βCD and Ada substitution level and on the mixture concentration. Benzophenone can be loaded into the structures without changes of their properties.

Disulfide core-crosslinked Plu-SH micelles are developed to deliver an encapsulated hydrophobic anticancer drug. At low DTT concentrations, the micelles are too stable to release the drug, but at higher DTT concentrations, the drug molecules are released from the micelles due to cleavage of the disulfide bond.

An electroactive carbon nanotube/poly(lactic acid) scaffold is created and characterized. The degradation profile after immersion in simulated physiological solutions at 37°C over a 28-day period is described, where the CNT appear to stabilize the mechanical properties and physical integrity of the scaffold. Furthermore, hMSC grown in the presence of this electroactive scaffold show no adverse cytotoxic response.