Dendrimer−Drug Conjugates for Tailored Intracellular Drug Release Based on Glutathione Levels

Abstract

N-Acetyl-L-Cysteine (NAC) is an anti-oxidant and anti-inflammatory agent with significant potential in clinical applications including stroke and neuroinflammation. The drug shows high plasma binding upon IV administration, requiring high doses and associated side effects. Through the use of an appropriate delivery vehicle, the stability and efficacy of NAC can be significantly improved. Dendrimers are an emerging class of nanoscale drug delivery vehicles, which enable high drug payloads and intracellular delivery. Poly(amidoamine) dendrimer-NAC conjugates having cleavable disulfide linkages are designed for intracellular delivery based on glutathione levels. We have successfully synthesized two conjugates of with a cationic G4-NH 2 and an anionic G3.5-COOH PAMAM dendrimers with NAC payloads of 16 and 18 per dendrimer, respectively, as confirmed by 1 H-NMR and MALDI-TOF analysis. NAC release kinetics of the conjugates at intracellular and extracellular Glutathione (GSH) concentrations were evaluated by reverse phase HPLC (RP-HPLC) analysis, and ~70% of NAC payload was released within one hour at intracellular GSH concentrations (~10 mM), whereas negligible NAC release was observed at extracellular GSH levels (2 µM). FITC-labeled conjugates showed that they enter cells rapidly and localize in the cytoplasm of lipopolysaccharide (LPS)-activated microglial cells (the target cells in vivo). The efficacies of dendrimer-NAC conjugates in activated microglial cells was confirmed by measuring the nitrite inhibition in the cell culture medium, which is an indication of the anti-oxidative property of the drug.Both G4-NH 2 and G3.5-COOH conjugates showed more significantly better nitrite inhibition both at 24 and 72 hours compared to free NAC, by as much as a factor of 16. The results indicate that PAMAM dendrimer conjugates produce a higher local NAC concentration inside the cells, with GSH-sensitive disulfide linker enabling efficient and rapid cellular release of the drug.

Preparation of Inert Polystyrene Latex Particles as MicroRNA Delivery Vectors by Surfactant-Free RAFT Emulsion Polymerization

“…Near-complete release of the therapeutic agent was achieved within 1 hour when the GSH concentration was increased to the maximum intracellular level. [51][52][53] Aiming to investigate if the releasing mechanism is as rapid in our system, we incubated the miRNA-nanoparticle conjugates with …”

Polyester Dendrimers: Smart Carriers for Drug Delivery

“…However, because the drug is delivered to the site of action extremely rapidly with IV injection, there is a risk of overdose if the dose has been calculated incorrectly, and there is an increased risk of side effects if the drug is administered too rapidly. Numerous reports of IV administered dendrimer-drug complexes have appeared [85][86][87][88][89]. For example, 2'-(benzo[1,2-c] 1,2,5-oxadiazol-5(6)-yl(N 1 -oxide) methylidene)-1-methoxy methane hydrazide presents antichagasic activity but has low water solubility.…”

Mucoadhesive Polymers for Oral Transmucosal Drug Delivery: A Review

“…Their structure and properties make them useful as vectors for gene delivery, excipients for enhancing aqueous solubility of poorly-soluble drugs, antimicrobial agents and drug conjugates [94,95]. Until today only few works have been published about the use of dendrimers as mucoadhesives.…”