Biosystems & Bioengineering, Polymer Science and Technology
Our primary research interests are in the area of polymeric biomaterials, with a special emphasis on elucidating the correlations between nanostructure, molecular interactions, properties and functionalities. We combine fundamental research with applied studies. Our goals are to advance the understanding of biomaterials, to develop new approaches in the field, and to seek creative ways to exploit polymers for biotechnological and medical applications.
A brief outline of some recent projects is given below:
Tran-mucosal drug delivery utilizes human entry passes such as the nasal and buccal cavities, which are covered with a moist gel-like layer termed mucus. Mucoadhesive polymers, capable of adhering to the mucus, facilitate drug absorption by prolonging residence time at the delivery site. We developed a new class of mucoadhesive polymers, which we termed acrylated polymers. These macromolecules carry at least one double bond capable of forming a covalent bonding with thiol groups on mucin type glycoproteins. We believe that acrylated polymers show great promise since combining the inherent properties of the backbone with acrylated side chains considerably enhances their mucoadhesiveness.
Vehicles for the delivery of hydrophobic drugs
More than 40% of the new medical entities developed since the late 1980s are extremely hydrophobic. These drugs can enter the hydrophobic cell membrane thus enable better targeting and drug efficiency. On the down side, low water solubility is related with low absorption, poor bioavailability and lack of dose-response proportionality. We have suggested several new platforms intended to face the challenging task of delivering hydrophobic drugs, and investigated their structure, properties, and release behavior. One scheme is based on composite hydrogels, an o/w (oil in water) microemulsion carrying a hydrophobic drug embedded in a hydrophilic polymer matrix. This approach enhances drug loading due to its higher solubility in the oil droplets, while the cross-linked hydrogel matrix can be readily used as a solid controlled delivery system. The resulting device has a high mechanical strength and has the potential of delivery in various routes, including oral and mucosal. We have recently shown that this approach is very effective in delivering nitroxides to skin cells and tissues. Another scheme involves entrapping hydrophobic molecules in nanoparticles prepared from positively charged polymers. This approach is expected to be useful in cancer therapy, since the enhanced permeability of tumor vasculature allows penetration of nanoparticles, whereas normal blood vessels exclude them. Thus, nanoparticles as drug carriers are an attractive alternative to conventional delivery methods because they can target tumors and have limited toxicity to normal tissue.
Fundamental studies of polysaccharide nanostructure
Polysaccharides are naturally occurring polymers which are considered to be attractive candidates for biomedical applications due to lack of toxicity, biocompatibility, biodegradability, relatively low cost, and ease of chemical modification. Like many other research groups, we utilized polysaccharides in some of our studies. The more we used these fascinating materials, the more we became to realized that many of their fundamental aspects are not fully understood. In particular, nanostructure investigations are in many cases missing in the literature. Revealing and understanding the nanostructure and its influence on the properties has become an important research theme in our group. We published the first comprehensive study of the conformation of alginate solutions. This study is one of the few experimental small angle scattering studies aimed at corroborating the proposed theories in this field. We investigated the nanostructure calcium-pectin and thermorevisable pectin-chitosan hydrogels. A quantitative analysis of alginate swelling revealed the deviation from the classic swelling theories, and the extreme sensitivity of chitosan hydrogels to pH was described for the first time.
I. Ventura and H. Bianco-Peled, “Small-Angle X-Ray Scattering Study on Pectin-Chitosan Mixed Solutions and Thermoreversible Gels”, Carbohydrate Polymers 123, 122-129, 2015.
K. Delmar and H. Bianco-Peled, “The Dramatic Effect of Small pH Changes on the Properties of Chitosan Hydorgels Crosslinked with Ggenipin”, Carbohydrate Polymers 127, 28-37, 2015.
O. Yom-tov, D. Seliktar and H. Bianco-Peled, “A Modified Emulsion Gelation Technique to Improve Buoyancy of Hydrogel Tablets for Floating Drug Delivery Systems”, Materials Science and Engineering C 55(1), 335-342, 2015.
L. Neufeld and H. Bianco-Peled, “Designing a Biocompatible Hydrogel for the Delivery of Mesalamine”, International Journal of Pharmaceutics 491(1-2), 170-179, 2015.
K. Delmar and H. Bianco-Peled, “Composite Chitosan Hydrogels for Extended Release of Hydrophobic Drugs”, Carbohydrate Polymers, in press.
O. Yom-tov, D. Seliktar and H. Bianco-Peled, PEG-Thiol based hydrogels with controllable properties”, European Polymer Journal, in press.
T. Eshel-Green and H. Bianco-Peled, “Mocuadhesive Acrylated Block Copolymers Micelles for the Delivery of Hydrophobic Drugs”, Colloids and Surfaces B: Biointerfaces, in press.