Environmentally benign production of cupric oxide nanoparticles and various utilizations of their polymeric hybrids in different technologies

Alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications to date, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers.

Poly(ethylene glycol) (PEG) is the most used polymer and also the gold standard for stealth polymers in the emerging field of polymer-based drug delivery. The properties that account for the overwhelming use of PEG in biomedical applications are outlined in this Review. The first approved PEGylated products have already been on the market for 20 years. A vast amount of clinical experience has since been gained with this polymer--not only benefits, but possible side effects and complications have also been found. The areas that might need consideration and more intensive and careful examination can be divided into the following categories: hypersensitivity, unexpected changes in pharmacokinetic behavior, toxic side products, and an antagonism arising from the easy degradation of the polymer under mechanical stress as a result of its ether structure and its non-biodegradability, as well as the resulting possible accumulation in the body. These possible side effects will be discussed in this Review and alternative polymers will be evaluated.

Alginates have become an extremely important family of polysaccharides because of their utility in preparing hydrogels at mild pH and temperature conditions, suitable for sensitive biomolecules like proteins and nucleic acids, and even for living cells such as islets of Langerhans. In addition, the complex monosaccharide sequences of alginates, and our growing ability to create controlled sequences by the action of isolated epimerases upon the alginate precursor poly(mannuronic acid), create remarkable opportunities for understanding the relationship of properties to sequence in natural alginates (control of monosaccharide sequence being perhaps the greatest synthetic challenge in polysaccharide chemistry). There is however a trend in recent years to create "value-added" alginates, by performing derivatization reactions on the polysaccharide backbone. For example, chemical derivatization may enable alginates to achieve enhanced hydroxyapatite (HAP) nucleation and growth, heparin-like anticoagulation properties, improved cell-surface interactions, degradability, or tuning of the hydrophobic-hydrophilic balance for optimum drug release. The creation of synthetic derivatives therefore has the potential to empower the next generation of applications for alginates. Herein we review progress towards controlled synthesis of alginate derivatives, and the properties and applications of these derivatives. Copyright © 2012 Elsevier Ltd. All rights reserved.