Dual polymer networks: a new strategy in expanding the repertoire of hydrogels for biomedical applications

Inspired by the double network hydrogel systems we report the formulation of dual networks, which expands the repertoire of this class of materials for potential biomedical applications. The tough dual network hydrogels were designed through sequential interpenetrating polymer formation, applying green chemistry and low-cost methods, devoid of any initiator-activator complexes that may pose risks in biomedical applications. The dual networks were synthesized in two steps, firstly the water soluble poly(vinyl alcohol) was subjected to cryogelation that formed the first network, which was then expanded by intrusion of a dilute solution of sodium alginate and complexed with a solution of calcium chloride under ambient conditions and further freeze-thawed. These hydrogels are flexible, ductile and porous with the ability to absorb and retain fluids as well as possess the versatility to easily incorporate biological molecules/drugs/antibiotics to be applied in tissue matrices or drug delivery systems. The dual network hydrogels can be tailored to have varying mechanical properties, shapes, size, thickness and particularly can be made physically porous if required, to suit the users intended application.

Magnetic conjugated polymer nanoparticles doped with a europium complex for biomedical imaging

Self-assembling conjugated polymer nanoparticles containing PVK and PLGA-PEG as a matrix polymer were doped with both a luminescent rare-earth complex and magnetic nanoparticles (SPIONs), giving rise to materials that are both luminescent and magnetic.

Bright conjugated polymer nanoparticles containing a biodegradable shell produced at high yields and with tuneable optical properties by a scalable microfluidic device

This study compares the performance of a microfluidic technique and a conventional bulk method to manufacture conjugated polymer nanoparticles (CPNs) embedded within a biodegradable poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG_5K-PLGA_55K) matrix. The influence of PEG_5K-PLGA_55K and conjugated polymers cyano-substituted poly(p-phenylene vinylene) (CN-PPV) and poly(9,9-dioctylfluorene-2,1,3-benzothiadiazole) (F8BT) on the physicochemical properties of the CPNs was also evaluated. Both techniques enabled CPN production with high end product yields (∼70-95%). However, while the bulk technique (solvent displacement) under optimal conditions generated small nanoparticles (∼70-100 nm) with similar optical properties (quantum yields ∼35%), the microfluidic approach produced larger CPNs (140-260 nm) with significantly superior quantum yields (49-55%) and tailored emission spectra. CPNs containing CN-PPV showed smaller size distributions and tuneable emission spectra compared to F8BT systems prepared under the same conditions. The presence of PEG_5K-PLGA_55K did not affect the size or optical properties of the CPNs and provided a neutral net electric charge as is often required for biomedical applications. The microfluidics flow-based device was successfully used for the continuous preparation of CPNs over a 24 hour period. On the basis of the results presented here, it can be concluded that the microfluidic device used in this study can be used to optimize the production of bright CPNs with tailored properties with good reproducibility.

Bright, near infrared emitting PLGA–PEG dye-doped CN-PPV nanoparticles for imaging applications

In this publication, we describe the synthesis of near-IR emitting conjugated polymer nanoparticles with an engineered surface, and their use in biological imaging.

Aptamer-modified polymer nanoparticles for targeted drug delivery

The purpose of this study was to develop a model system for targeted drug delivery. This system should enable targeted drug release at a certain tissue in the body. In conventional drug delivery systems, drugs are often delivered unspecifically resulting in unwarranted adverse effects. To circumvent this problem, there is an increasing demand for the development of intelligent drug delivery systems allowing a tissue-specific mode of delivery. Within this study, nanoparticles consisting of two biocompatible polymers are used. Because of their small size, nanoparticles are well-suited for effective drug delivery. The small size affects their movement through cell and tissue barriers. Their cellular uptake is easier when compared to larger drug delivery systems. Paclitaxel was encapsulated into the nanoparticles as a model drug, and to achieve specific targeting an aptamer directed against lung cancer cells was coupled to the nanoparticles surface. Nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), and nanotracking analysis (NTA). Also their surface charge was characterized from ζ-potential measurements. Their preparation was optimized and subsequently specificity of drug-loaded and aptamer-functionalized nanoparticles was investigated using lung cancer cells.

Red-emitting protein-coated conjugated polymer nanoparticles

Red emitting materials are desirable in biology due to the transparency of certain biological tissues at these wavelengths.