In order to better understand nanoparticle uptake and elimination mechanisms, we designed a controlled set of small, highly fluorescent quantum dots (QDs) with nearly identical hydrodynamic size (8À10 nm) but with varied short ligand surface functionalization. The properties of functionalized QDs and their modes of uptake and elimination were investigated systematically by asymmetrical flow fieldÀflow fractionation (AF4), confocal fluorescence microscopy, flow cytometry (FACS), and flame atomic absorption (FAA). Using specific inhibitors of cellular uptake and elimination machinery in human embryonic kidney cells (Hek 293) and human hepatocellular carcinoma cells (Hep G2), we showed that QDs of the same size but with different surface properties were predominantly taken up through lipid raft-mediated endocytosis, however, to significantly different extents. The latter observation infers the contribution of additional modes of QD internalization, which include X-AG cysteine transporter for cysteine-functionalized QDs (QD-CYS).We also investigated putative modes of QD elimination and established the contribution of P-glycoprotein (P-gp) transporter in QD efflux. Results from these studies show a strong dependence between the properties of QD-associated small ligands and modes of uptake/elimination in human cells.

The objective of this study is to provide a novel synthetic approach for the manufacture of wound-healing materials using covalently cross-linked alginate fi bers loaded with silver nanoparticles. Alginate fi bers are prepared by wet-spinning in a CaCl 2 precipitation bath. Using this same approach, calcium cross-links in alginate fi bers are replaced by chemical cross-links that involve hydroxyl groups for subsequent cross-linking by glutaraldehyde. The cross-linked fi bers become highly swollen in aqueous solution due to the presence of carboxyl functional groups, and retain their mechanical stability in physiological fl uids owing to the stabilized network of covalent bonds. Alginate fi bers can then be loaded with silver ions via the ion-exchange reaction. Silver ions are reduced to yield 11 nm silver nanoparticles incorporated in the polymer gel. This method provides a convenient platform to incorporate silver nanoparticles into alginate fi bers in controlled concentrations while retaining the mechanical and swelling properties of the alginate fi bers. Our study suggests that the silver nanoparticles loaded fi bers may be easily applied in a wound healing paradigm and promote the repair process though the promotion of fi broblast migration to the wound area, reduction of the infl ammatory phase, and the increased epidermal thickness in the repaired wound area, thereby improving the overall quality and speed of healing.

Cellular adaptation is the dynamic response of a cell to adverse changes in its intra/extra cellular environment. The aims of this study were to investigate the role of: (i) the glutathione antioxidant system, and (ii) the transcription factor EB (TFEB), a newly revealed master regulator of lysosome biogenesis, in cellular adaptation to nanoparticle-induced oxidative stress. Intracellular concentrations of glutathione species and activation of TFEB were assessed in rat pheochromocytoma (PC12) cells following treatment with uncapped CdTe quantum dots (QDs), using biochemical, live cell fluorescence and immunocytochemical techniques. Exposure to toxic concentrations of QDs resulted in a significant enhancement of intracellular glutathione concentrations, redistribution of glutathione species and a progressive translocation and activation of TFEB. These changes were associated with an enlargement of the cellular lysosomal compartment. Together, these processes appear to have an adaptive character, and thereby participate in the adaptive cellular response to toxic nanoparticles.

Bi-and trifunctional dendrimer and miktoarm nanocarriers, containing a combination of covalently linked model drug (R-lipoic acid), fluorescent dye (BODIPY), and poly(ethylene glycol) (PEG), are synthesized using a core with orthogonal functional groups, on which Huisgen alkyne-azide "click" reactions are performed in sequence. These carriers are internalized into the cells where they reduce H 2 O 2 induced reactive oxygen species formation. In addition, miktoarm nanocarriers conjugated with R-lipoic acid enhance intracellular glutathione (GSH) concentrations.

These studies explore the relationship between the inhibitory actions of low generation dendrimers in stimulated microglia and dendrimer−enzyme interactions using in silico molecular modeling. Low generation (DG0 and DG1) dendrimers with acetylene and hydroxyl terminal groups were tested for their anti-inflammatory activity in microglia stimulated by lipopolysaccharides (LPS), and the results were compared with those from the established anti-inflammatory agents, ibuprofen and celecoxib. We hypothesized that hydroxyl terminal groups of DG0 and DG1 dendrimers could interact with the active sites of the inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) enzymes due to their small size and favorable electrochemical properties. The enzymatic activity of iNOS and COX-2 was determined in the presence of low generation dendrimers using biochemical assays and their values related to dendrimer docking confirmations from in silico molecular modeling. We found that results from the molecular modeling studies correlated well with the in vitro biological data, suggesting that, indeed, hydroxyl terminal groups of low generation dendrimers enable multivalent macromolecular interactions, resulting in the inhibition of both iNOS and COX-2 enzymes.