Microwave-Assisted Synthesis of Associative Hydrogels

Design of polymer-based antimicrobial hydrogels through physico-chemical transition

The antimicrobial activity represents a cornerstone in the development of biomaterials: it is a leading request in many areas, including biology, medicine, environment and industry. Over the years, different polymeric scaffolds are proposed as solutions, based on the encapsulation of metal ions/particles, antibacterial agents or antibiotics. However, the compliance with the biocompatibility criteria and the concentration of the active principles to avoid under- and over-dosing are being debated. In this work, we propose the synthesis of a versatile hydrogel using branched polyacrylic acid (carbomer 974P) and aliphatic polyetherdiamine (elastamine®) through physico-chemical transition, able to show its ability to counteract the bacterial growth and infections thanks to the polymers used, that are not subjected to further chemical modifications. In particular, the antimicrobial activity is clearly demonstrated against Staphyloccoccus aureus and Candida albicans, two well-known opportunistic pathogens. Moreover, we discuss the hydrogel use as drug carrier to design a unique device able to combine the antibacterial/antimicrobial properties to the controlled drug delivery, as a promising tool for a wide range of biomedical applications.

Evaluation of thermoresponsive properties and biocompatibility of polybenzofulvene aggregates for leuprolide delivery

In this study, a polybenzofulvene derivative named poly-6-MOEG-9-BF3k, was evaluated as polymeric material for the production of injectable thermoresponsive nano-aggregates able to load low molecular weight peptidic drug, like the anticancer leuprolide. Thermoresponsive behavior of poly-6-MOEG-9-BF3k was studied in aqueous media by evaluating scattering intensity variations by means of DLS in function of temperature. Zeta potential measurements and SEM observations were also carried out. Moreover, critical aggregation temperature of the poly-6-MOEG-9-BF3k polymer was evaluated by pyrene fluorescence analysis. Then, the ability of prepared thermoresponsive aggregates to protect this model oligopeptide drug and regulate its release rate in function of external temperature was evaluated in vitro. Finally, biocompatibility of poly-6-MOEG-9-BF3k aggregates was tested in vitro on a healthy cell line (human bronchial epithelial cell; 16-HBE) and in vivo on rat animal model upon subcutaneous administration.

Cyclodextrin-based polymeric materials: synthesis, properties, and pharmaceutical/biomedical applications

This review describes the synthesis, properties, and, in particular, biomedical and pharmaceutical applications of an upcoming class of polymeric networks and assemblies based on cyclodextrins (CDs). CDs are cyclic oligosaccharides composed of alpha-1,4-coupled d-glucose units, which contain a hydrophobic internal cavity that can act as a host for various, generally lipophilic, guest molecules. Because of this unique physicochemical property, commonly referred to as inclusion complex formation, CDs have often been used to design polymeric materials, such as hydrogels and nanoparticles. Polymeric systems based on CDs exhibit unique characteristics in terms of mechanical properties, stimuli-responsiveness, and drug release characteristics. In this contribution, first, an outline is given of covalently cross-linked polymeric networks in which CD moieties were structurally incorporated to modulate the network strength as well as the complexation and release of low molecular weight drugs. Second, physically assembled polymeric systems are discussed, of which the formation is accomplished by inclusion complexes between polymer-conjugated CDs and various guest molecule-derivatized polymers. Due to their physical nature, these polymeric systems are sensitive to external stimuli, such as temperature changes, shear forces and the presence of competing CD-binding molecules, which can be exploited to use these systems as injectable, in situ gelling devices. In recent years, many interesting CD-containing polymeric systems have been described in literature. These systems have to be optimized and extensively evaluated in preclinical studies concerning their safety and efficacy, making future clinical applications of these materials in the biomedical and pharmaceutical field feasible.

Recent Advances in Microwave-Assisted Polymer Synthesis

In the past few years the use of microwave irradiation in polymer science has become a well-established technique to drive and promote chemical reactions. The main advantages of microwave heating are a strong reduction in reaction time and a high potential to contribute to green and sustainable chemistry. This article provides a short review of recent examples in the field of microwave-assisted polymer synthesis with special emphasis on radical polymerizations, step-growth polymerizations, ring-opening polymerizations, and polymer modifications.