DVS supports are very suitable to stabilize enzymes via multipoint covalent attachment.

Aimsto design calcium and zinc-loaded bioactive and cytocompatible nanoparticles for the treatment of periodontal disease.MethodsPolymP-nActive nanoparticles were zinc or calcium loaded. Biomimetic calcium phosphate precipitation on polymeric particles was assessed after 7 days immersion in simulated body fluid, by scanning electron microscopy attached to an energy dispersive analysis system. Amorphous mineral deposition was probed by X-ray diffraction. Cell viability analysis was performed using oral mucosa fibroblasts by: 1) quantifying the liberated deoxyribonucleic acid from dead cells, 2) detecting the amount of lactate dehydrogenase enzyme released by cells with damaged membranes, and 3) by examining the cytoplasmic esterase function and cell membranes integrity with a fluorescence-based method using the Live/Dead commercial kit. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests.ResultsPrecipitation of calcium and phosphate on the nanoparticles surfaces was observed in calcium-loaded nanoparticles. Non-loaded nanoparticles were found to be non-toxic in all the assays, calcium and zinc-loaded particles presented a dose dependent but very low cytotoxic effect.ConclusionsThe ability of calcium-loaded nanoparticles to promote precipitation of calcium phosphate deposits, together with their observed non-toxicity may offer new strategies for periodontal disease treatment.

This work highlights the relevance of the interactions between polymer and solvent during precipitation polymerization in order to control the morphology and the size of the precipitated material without any changes in chemical composition. Thus, a thermodynamic model based on Flory Hugings model and Hansen's solubility parameters has been proposed in order to control the precipitation process. This model is based on the study and characterization of the interactions (hydrogen-bonding forces, polar forces and dispersion forces) between growing polymeric chains and solvent molecules. The model was corroborated by more than 80 different solvent compositions were used for a ternary solvent mixture (toluene, acetonitrile and 2-propanol) and two different monomer molar ratio feeds (45% MAA, 20% HEMA, and 35% EDMA; 20% MAA, 45% HEMA, and 35% EDMA). The morphologies of the resulting polymer material were characterized by scanning electron microscopy and transmission electron microscopy and the particles sizes were deduced by dynamic light scattering. The polymeric particles with different sizes prepared in this work were used to introduce on them magnetic properties. The results in this work enable the control of the size, chemical composition, and the homogeneous encapsulation of Fe 3 O 4 within different hydrophilic polymeric matrixes by polymerization precipitation, allowing the design of magnetic particles free of any stabilizers.

To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium-and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP-nActive nanoparticles (nanoMyP) were zincloaded through 30-minute ZnCl 2 immersion and tested for bioactivity by means of 7 days' immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be incorporated into dental adhesive systems to provide the appropriate environment in which dentin MMP collagen degradation is inhibited and mineral growth can occur.