Synergistic Sustained Drug-Release System Based on Immobilized Rhamnus frangula L. Phytoextract into Layered Double Hydroxide Covered by Biocompatible Hydrogel.

This work focuses on the synergetic effect obtained by immobilization of Rhamnus frangula L. (RfL) phytoextract in layered double hydroxides (LDHs) matrixes and their subsequent encapsulation into biocompatible hydrogels (HG). In this respect, the LDHs were used as hosts for the immobilization of the phytoextract by a reconstruction method, after which the LDHsRfL were embedded into biocompatible hydrogel (HG) matrixes, based on polyethylene glycol diacrylate (PEGDA), by a radical polymerization reaction. The resulted biocompatible hydrogel composites were characterized by modern methods, while the swelling and rheology measurements revealed that the HG composites steadily improved as the content of RfL phytoextract immobilized on LDHs (LDHsRfL) increased. The following in vitro sustained release of the RfL phytoextract was highlighted by measurements at pH 6.8, in which case the composite HGs with LDHsRfL presented an improved release behavior over the LDHsRfL, thus, underlining the synergistic effect of PEGDA network and LDH particles on the slow-release behavior. The kinetic models used in the RfL release from composite HGs clearly indicate that the release is diffusion controlled in all the cases. The final composite HGs described here may find applications in the pharmaceutical field as devices for the controlled release of drugs.

Molecularly Imprinted Ligand-Free Nanogels for Recognizing Bee Venom-Originated Phospholipase A2 Enzyme.

In this study, ligand-free nanogels (LFNGs) as potential antivenom mimics were developed with the aim of preventing hypersensitivity and other side effects following massive bee attacks. For this purpose, poly (ethylene glycol) diacrylate was chosen as a main synthetic biocompatible matrix to prepare the experimental LFNGs. The overall concept uses inverse mini-emulsion polymerization as the main route to deliver nanogel caps with complementary cavities for phospholipase A2 (PLA2) from bee venom, created artificially with the use of molecular imprinting (MI) technologies. The morphology and the hydrodynamic features of the nanogels were confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. The following rebinding experiments evidenced the specificity of molecularly imprinted LFNG for PLA2, with rebinding capacities up to 8-fold higher compared to the reference non-imprinted nanogel, while the in vitro binding assays of PLA2 from commercial bee venom indicated that such synthetic nanogels are able to recognize and retain the targeted PLA2 enzyme. The results were finally collaborated with in vitro cell-viability experiments and resulted in a strong belief that such LFNG may actually be used for future therapies against bee envenomation.