Patterning poly(organophosphazenes) for selective cell adhesion applications

Preparation and Properties of Novel Crosslinked Polyphosphazene-Aromatic Ethers Organic-Inorganic Hybrid Microspheres

A series of novel crosslinked polyphosphazene-aromatic ether organic-inorganic hybrid microspheres with different structures were prepared via precipitation polycondensation between hexachlorocyclotriphosphazene (HCCP) and bisphenol monomers. The bisphenol monomers have different numbers of -CF₃ in the side group, which correspond to distinct oligomeric species-absorbing mechanisms. The wetting behavior of the microsphere surface was evaluated using a water contact angle (CA) measurement, which increased with the increase in the content of -CF₃ in polyphosphazene. We also investigated the effects of HCCP concentration and ultrasonic power on the morphology of the microspheres.

Functionalizing PLGA and PLGA Derivatives for Drug Delivery and Tissue Regeneration Applications

Poly(lactic-co-glycolic) acid (PLGA) is one of the most versatile biomedical polymers, already approved by regulatory authorities to be used in human research and clinics. Due to its valuable characteristics, PLGA can be tailored to acquire desirable features for control bioactive payload or scaffold matrix. Moreover, its chemical modification with other polymers or bioconjugation with molecules may render PLGA with functional properties that make it the Holy Grail among the synthetic polymers to be applied in the biomedical field. In this review, the physical-chemical properties of PLGA, its synthesis, degradation, and conjugation with other polymers or molecules are revised in detail, as well as its applications in drug delivery and regeneration fields. A particular focus is given to successful examples of products already on the market or at the late stages of trials, reinforcing the potential of this polymer in the biomedical field.

Glycosylation of polyphosphazenes by thiol-yne click chemistry for lectin recognition

Strong carbohydrate–lectin binding interactions in biological systems can be mimicked through the synthesis of glucose containing macromolecules, particularly glycosylated polymers.

Phosphorous-containing polymers for regenerative medicine

Disease and injury have resulted in a large, unmet need for functional tissue replacements. Polymeric scaffolds can be used to deliver cells and bioactive signals to address this need for regenerating damaged tissue. Phosphorous-containing polymers have been implemented to improve and accelerate the formation of native tissue both by mimicking the native role of phosphorous groups in the body and by attachment of other bioactive molecules. This manuscript reviews the synthesis, properties, and performance of phosphorous-containing polymers that can be useful in regenerative medicine applications.

A facile method to prepare composite and porous polyphosphazene membranes and investigation of their properties

Polyphosphazene/SiO₂ composite membranes and porous polyphosphazene membranes were prepared and their properties were studied in detail.

A gaussian model for substrates of entangled cross-linked poly(ethylene glycol) in biomedical applications

Cells usually spread on a synthetic substrate through bonds between receptors and chemical groups on the substrate (ligands). Therefore, it is valuable to study the effects of the average number density of these chemical groups and the average distance between them to model and predict the cell behavior. Poly(ethylene glycol) [PEG] modified with peptide groups has been used widely in biomedical applications as a substrate material. In this study, a coarse-grained model is proposed for PEG to predict the average number density of ligands and the average distance between them. Molecular information such as initial molecular weight distribution, average molecular weight between cross-links, and average molecular weight between entanglements is used as input parameters. Based on simulation results, it is concluded that both entanglement and cross-link densities are required to create a network structure. The results suggest that an average initial molecular weight 2-3 times the average molecular weight between entanglements and a moderate cross-link density are sufficient to create a closed network structure with a high ligand density and a small average distance between them.

Stamps, inks and substrates: polymers in microcontact printing

It's all about polymers! Polymers play a key role in the patterning and functionalization of surfaces by microcontact printing. Polymers are versatile stamps, inks and substrates and microcontact printing can provide microstructured polymer surfaces in a single printing step.

Elasticity-based patterning of red blood cells on undulated lipid membranes supported on porous topographic substrates

We describe elasticity-based patterning of human red blood cells (RBCs) into a microarray form on supported lipid membranes (SLMs) prepared on a solid substrate having two types of topographic patterns, porous and flat regions. The underlying concept is to precisely control the interplay between adhesion and the bending rigidity of the RBCs that interact with the SLMs. Attachment of the RBCs on highly undulated SLMs formed on the porous region is not energetically favorable, since membrane bending of the RBCs costs a high curvature elastic energy which exceeds adhesion. The RBCs are thus selectively confined within relatively flat regions of the SLMs without causing considerable elastic distortions. It was found that the population of the RBCs in a single corral is linearly proportional to the area of one element in our microarray.

Inductive tissue engineering with protein and DNA-releasing scaffolds

Cellular differentiation, organization, proliferation and apoptosis are determined by a combination of an intrinsic genetic program, matrix/substrate interactions, and extracellular cues received from the local microenvironment. These molecular cues come in the form of soluble (e.g. cytokines) and insoluble (e.g. ECM proteins) factors, as well as signals from surrounding cells that can promote specific cellular processes leading to tissue formation or regeneration. Recent developments in the field of tissue engineering have employed biomaterials to present these cues, providing powerful tools to investigate the cellular processes involved in tissue development, or to devise therapeutic strategies based on cell replacement or tissue regeneration. These inductive scaffolds utilize natural and/or synthetic biomaterials fabricated into three-dimensional structures. This review summarizes the use of scaffolds in the dual role of structural support for cell growth and vehicle for controlled release of tissue inductive factors, or DNA encoding for these factors. The confluence of molecular and cell biology, materials science and engineering provides the tools to create controllable microenvironments that mimic natural developmental processes and direct tissue formation for experimental and therapeutic applications.