Preparation, characterization, andin vitrodrug release behavior of glutathione-sensitive long-circulation micelles based on polyethylene glycol prodrug

Polymer-Based Nanoparticles as Drug Delivery Systems for Purines of Established Importance in Medicine

Many purine derivatives are active pharmaceutical ingredients of significant importance in the therapy of autoimmune diseases, cancers, and viral infections. In many cases, their medical use is limited due to unfavorable physicochemical and pharmacokinetic properties. These problems can be overcome by the preparation of the prodrugs of purines or by combining these compounds with nanoparticles. Herein, we aim to review the scientific progress and perspectives for polymer-based nanoparticles as drug delivery systems for purines. Polymeric nanoparticles turned out to have the potential to augment antiviral and antiproliferative effects of purine derivatives by specific binding to receptors (ASGR1-liver, macrophage mannose receptor), increase in drug retention (in eye, intestines, and vagina), and permeation (intranasal to brain delivery, PEPT1 transport of acyclovir). The most significant achievements of polymer-based nanoparticles as drug delivery systems for purines were found for tenofovir disoproxil in protection against HIV, for acyclovir against HSV, for 6-mercaptopurine in prolongation of mice ALL model life, as well as for 6-thioguanine for increased efficacy of adoptively transferred T cells. Moreover, nanocarriers were able to diminish the toxic effects of acyclovir, didanosine, cladribine, tenofovir, 6-mercaptopurine, and 6-thioguanine.

GSH/enzyme-responsive 2-sulfonyl-1-methylimidazole prodrug for enhanced transdermal drug delivery and therapeutic efficacy against hyperthyroidis

Novel GSH/enzyme-responsive anti-hyperthyroidism prodrugs designed for transdermal delivery of 2-sulfonyl-1- methylimidazole (MMI) were synthesized by a Michael addition reaction of MMI with propiolic acid (PA) followed by esterification with three long chain fatty alcohols and their structures were characterized by ¹H-NMR, ¹³C-NMR and mass spectrometry. Their maximum steady state flux through rat skin in the PG/W solution was found to be more than 37-times faster than that of MMI. The result may be attributed to the improved lipophilicity of prodrug and rapid bioconversion. The prodrugs were hydrolyzed by esterase on passing through the skin and appeared mainly as intermediate MMI-PA in the receiver compartment and accompanied by a small amount of MMI and intact prodrug. The prodrugs did not release any MMI in the media without GSH or with 100 µM GSH, while the obvious MMI release could be observed within 6.4 h in the media containing 2 mM and 10 mM GSH, and their maximum cumulative release rates reached 95.07% for lauryl alcohol ester prodrug (MMI-PA-OLa). MMI-PA-OLa exhibited a significant inhibition effect on lactoperoxidase (LPO) after being incubated in millimolar GSH media, whose inhibition rate was very similar to that of free MMI with an equivalent dose. These results suggested that MMI-PA-OLa could pass efficiently through the skin and release MMI in response to the intracellular environment.

Co-delivery Systems of Multiple Drugs Using Nanotechnology for Future Cancer Therapy

Cancer treatments have improved significantly during the last decade but are not yet satisfactory. Combination therapy is often administered to improve efficacy and safety. Drug delivery systems can also improve efficacy and safety. To control the spatiotemporal distribution of drugs, nanotechnology involving liposomes, solid lipid nanoparticles, and polymeric micelles has been developed. Co-delivery systems of multiple drugs are a promising approach to combat cancer. Synergistic effects and reduced side effects are expected from the use of co-delivery systems. In this review, we summarize various co-delivery systems for multiple drugs, including small-molecule drugs, nucleic acids, genes, and proteins. Co-delivery of drugs with different properties is relatively difficult, but some researchers have succeeded in developing such co-delivery systems. Environment-responsive carrier designs can control the release of cargos. Although their preparation is more complicated than that of mono-delivery systems, co-delivery systems can simplify clinical procedures and improve patient QOL.

Glutathione responsive poly(HPMA) conjugate nanoparticles for efficient 6-MP delivery

GSH-sensitive poly(HPMA)–PTA was developed and its antitumor effect on HepG2 cells was evaluated.

Micelle-Forming Dexamethasone Prodrug Attenuates Nephritis in Lupus-Prone Mice without Apparent Glucocorticoid Side Effects

Nephritis is one of the major complications of systemic lupus erythematosus. While glucocorticoids (GCs) are frequently used as the first-line treatment for lupus nephritis (LN), long-term GC usage is often complicated by severe adverse effects. To address this challenge, we have developed a polyethylene glycol-based macromolecular prodrug (ZSJ-0228) of dexamethasone, which self-assembles into micelles in aqueous media. When compared to the dose equivalent daily dexamethasone 21-phosphate disodium (Dex) treatment, monthly intravenous administration of ZSJ-0228 for two months significantly improved the survival of lupus-prone NZB/W F1 mice and was much more effective in normalizing proteinuria, with clear histological evidence of nephritis resolution. Different from the dose equivalent daily Dex treatment, monthly ZSJ-0228 administration has no impact on the serum anti-double-stranded DNA (anti-dsDNA) antibody level but can significantly reduce renal immune complex deposition. No significant systemic toxicities of GCs ( e. g., total IgG reduction, adrenal gland atrophy, and osteopenia) were found to be associated with ZSJ-0228 treatment. In vivo imaging and flow cytometry studies revealed that the fluorescent-labeled ZSJ-0228 primarily distributed to the inflamed kidney after systemic administration, with renal myeloid cells and proximal tubular epithelial cells mainly responsible for its kidney retention. Collectively, these data suggest that the ZSJ-0228's potent local anti-inflammatory/immunosuppressive effects and improved safety may be attributed to its nephrotropicity and cellular sequestration at the inflamed kidney tissues. Pending further optimization, it may be developed into an effective and safe therapy for improved clinical management of LN.

pH and reduction-activated polymeric prodrug nanoparticles based on a 6-thioguanine-dialdehyde sodium alginate conjugate for enhanced intracellular drug release in leukemia

Synthesis schematics of DSA and 6-TG-DSA as well as processes of PPN self-assembly and its pH/GSH dual stimuli-response release of the conjugated 6-TG.

Marrying multicomponent reactions and aggregation-induced emission (AIE): new directions for fluorescent nanoprobes

Recent development and progress for fabrication and applications of aggregation-induced emission polymers through multicomponent reactions have been summarized in this review.