“Clip” and “Click” Chemistries Combination: Toward Easy PEGylation of Degradable Aliphatic Polyesters

Mechanistic applications of click chemistry for pharmaceutical drug discovery and drug delivery

The concept of click chemistry (CC), first introduced by K.B. Sharpless, has been widely adopted for use in drug discovery, novel drug delivery systems (DDS), polymer chemistry, and material sciences. In this review, we outline novel aspects of CC related to drug discovery and drug delivery, with a brief overview of molecular mechanisms underlying each click reaction commonly used by researchers, and the main patents that paved the way for further diverse medicinal applications. We also describe recent progress in drug discovery and polymeric and carbon material-based drug delivery for potential pharmaceutical applications and advancements based on the CC approach, and discuss some intrinsic limitations of this popular conjugation reaction. The use of CC is likely to significantly advance drug discovery and bioconjugation development.

Development of functionalized nanoparticles for vaccine delivery to dendritic cells: a mechanistic approach

AIM

Produce biodegradable nanoparticles to target antigen-presenting cells (APCs) and evaluate their potential to be used as a vaccine delivery system.

MATERIALS & METHODS

Untargeted PEGylated poly(d,l-lactic-co-glycolide)-based nanoparticles and mannose-grafted nanoparticles were formulated and physicochemically characterized. Immortalized and primary APCs were used to study nanoparticle internalization patterns. The endocytic pathways and intracellular trafficking followed by nanoparticles were also investigated.

RESULTS & DISCUSSION

Nanoparticles displayed mannose residues available for binding at the nanoparticle surface. Different nanoparticle internalization patterns by immortalized and primary APCs were verified. Macropinocytosis, clathrin-mediated endocytosis, caveolin- and lipid raft-dependent endocytosis are involved in nanoparticles internalization. Nanoparticles demonstrate both endolysosomal and cytosolic localizations and a tendency to accumulate nearby the endoplasmic reticulum.

CONCLUSION

The developed nanoparticles might drive antigens to be presented through MHC class I and II molecules to both CD8(+) and CD4(+) T cells, favoring a complete and coordinated immune response.

In vivo delivery of peptides and Toll-like receptor ligands by mannose-functionalized polymeric nanoparticles induces prophylactic and therapeutic anti-tumor immune responses in a melanoma model

We hypothesized that the co-entrapment of melanoma-associated antigens and the Toll-like receptor (TLR) ligands Poly(I:C) and CpG, known to be Th1-immunopotentiators, in mannose-functionalized aliphatic polyester-based nanoparticles (NPs) could be targeted to mannose receptors on antigen-presenting cells and induce anti-tumor immune responses. High entrapment efficiencies of antigens and immunopotentiators in 150nm NPs were obtained. The co-entrapment of the model antigen ovalbumin and the TLR ligands was crucial to induce high IgG2c/IgG1 ratios and high levels of IFN-γ and IL-2. Mannose-functionalization of NPs potentiated the Th1 immune response. The nanoparticulate vaccines decreased the growth rate of murine B16F10 melanoma tumors in therapeutic and prophylatic settings. The combination of mannose-functionalized NPs containing MHC class I- or class II-restricted melanoma antigens and the TLR ligands induced the highest tumor growth delay. Overall, we demonstrate that the multifunctional properties of NPs in terms of targeting and antigen/adjuvant delivery have high cancer immunotherapeutic potential.

Immortal ring-opening polymerization of ε-caprolactone by a neat magnesium catalyst system: an approach to obtain block and amphiphilic star polymers in situ

Building of various functional and topological microstructured PCLs via the immortal catalyst system of MgⁿBu₂/ROH and click reaction.

Targeted nanoparticles with novel non-peptidic ligands for oral delivery

Orally administered targeted nanoparticles have a large number of potential biomedical applications and display several putative advantages for oral drug delivery, such as the protection of fragile drugs or modification of drug pharmacokinetics. These advantages notwithstanding, oral drug delivery by nanoparticles remains challenging. The optimization of particle size and surface properties and targeting by ligand grafting have been shown to enhance nanoparticle transport across the intestinal epithelium. Here, different grafting strategies for non-peptidic ligands, e.g., peptidomimetics, lectin mimetics, sugars and vitamins, that are stable in the gastrointestinal tract are discussed. We demonstrate that the grafting of these non-peptidic ligands allows nanoparticles to be targeted to M cells, enterocytes, immune cells or L cells. We show that these grafted nanoparticles could be promising vehicles for oral vaccination by targeting M cells or for the delivery of therapeutic proteins. We suggest that targeting L cells could be useful for the treatment of type 2 diabetes or obesity.

Synthesis of poly(lactide-co-glycolide-co-ε-caprolactone)-graft-mannosylated poly(ethylene oxide) copolymers by combination of "clip" and "click" chemistries

Poly(lactide-co-glycolide) (PLGA) is extensively used in pharmaceutical applications, for example, in targeted drug delivery, because of biocompatibility and degradation rate, which is easily tuned by the copolymer composition. Nevertheless, synthesis of sugar-labeled amphiphilic copolymers with a PLGA backbone is quite a challenge because of high sensitivity to hydrolytic degradation. This Article reports on the synthesis of a new amphiphilic copolymer of PLGA grafted by mannosylated poly(ethylene oxide) (PEO). A novel building block, that is, α-methoxy-ω-alkyne PEO-clip-N-hydroxysuccinimide (NHS) ester, was prepared on purpose by photoreaction of a diazirine containing molecular clip. This PEO block was mannosylated by reaction of the NHS ester groups with an aminated sugar, that is, 2-aminoethyl-α-d-mannopyroside. Then, the alkyne ω-end-group of PEO was involved in a copper alkyne- azide coupling (CuAAC) with the pendent azides of the aliphatic copolyester. The targeted mannose-labeled poly(lactide-co-glycolide-co-ε-caprolactone)-graft-poly(ethylene oxide) copolymer was accordingly formed. Copolymerization of d,l-lactide and glycolide with α-chloro-ε-caprolactone, followed by substitution of chlorides by azides provided the azido-functional PLGA backbone. Finally, micelles of the amphiphilic mannosylated graft copolymer were prepared in water, and their interaction with Concanavalin A (ConA), a glyco-receptor protein, was studied by quartz crystal microbalance. This study concluded to the prospect of using this novel bioconjugate in targeted drug delivery.