Fabrication of biodegradable micelles with reduction-triggered release of 6-mercaptopurine profile based on disulfide-linked graft copolymer conjugate

A Comprehensive Review on the Importance of Sustainable Synthesized Coinage Metal Nanomaterials and Their Diverse Biomedical Applications

From a historical perspective, coinage metals (CMNMs) are most renowned for their monetary, ornamental, and metallurgical merits; nevertheless, as nanotechnology's potential has only just come to light, their metal nanostructures and uses may be viewed as products of modern science. Notable characteristics of CMNMs include visual, electrical, chemical, and catalytic qualities that depend on shape and size. Due diligence on the creation and synthesis of CMNMs and their possible uses has been greatly promoted by these characteristics. This review focuses on solution-based methods and provides an overview of the latest developments in CMNMs and their bimetallic nanostructures. It discusses a range of synthetic techniques, including conventional procedures and more modern approaches used to enhance functionality by successfully manipulating the CMNMs nanostructure's size, shape, and composition. To help with the design of new nanostructures with improved capabilities in the future, this study offers a brief assessment of the difficulties and potential future directions of these intriguing metal nanostructures. This review focuses on mechanisms and factors influencing the synthesis process, green synthesis, and sustainable synthesis methods. It also discusses the wide range of biological domains in which CMNMs are applied, including antibacterial, antifungal, and anticancer. Researchers will therefore find the appropriateness of both synthesizing and using CMNMS keeping in mind the different levels of environmental effects.

Advanced therapeutic strategy: A single-dose injection of a dual-loaded 6-mercaptopurine gelatin-based hydrogel for effective inhibition of tumor growth

The suboptimal aqueous solubility and pronounced systemic toxicity pose significant constraints on the clinical utility of 6-mercaptopurine (6-MP). This study presents an innovative approach using injectable sustained-release hydrogels for localized drug delivery. A gelatin-based anticancer hydrogel (Gel-MP@Gel@6-MP) was developed to deliver 6-MP through both physical encapsulation and chemical coupling via CS bonds, providing a multistage sustained release platform. In vitro experiments demonstrated that physically encapsuled drug achieved rapid release within 4 h, comparable to intravenous administration kinetics. Furthermore, in the presence of glutathione (GSH), nucleophilic attack triggered slow release of S-(6-purinyl) glutathione (PG) and a minor amount of 6-MP, with sustained release observed for up to 96 h. This suggests that, in contrast to conventional delivery methods, the proposed system not only facilitates an initial high-concentration drug release lasting hours, but also enables the sustained release of drug fragments over an extended period of several days, owing to the gradual cleavage of chemical bonds following one single injection. Ultimately, in vivo antitumor studies revealed superior tumor inhibition with Gel-MP@Gel@6-MP compared to free 6-MP. This dual drug loading strategy significantly prolongs drug action duration and obviates the necessity for repeated drug administrations, thereby revealing the diverse modes of drug administration.

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.

Synthesis of HA-SS-MP: A Prodrug With High Specificity for Cancer Cells

Thiolated hyaluronic acid was synthesized, and a quantification method was established to determine the content of the thiol group. Three thiol compounds, 2-nitro-5-mercapto-benzoic acid (TNB), 2- mercaptonicotinic acid (2-MNA), and mercaptopyridine (MPD), were tested for their efficiency in forming adducts with hyaluronic acid (HA) through disulfide bonds. Our results showed that MPD exhibited the highest disulfide exchange efficiency when the reaction was conducted at the optimal pH value. The synthesized hyaluronic acid-SS-mercaptopurine (HA-SS-MP) was characterized by1H-nuclear magnetic resonance spectroscopy. The HA-SS-MP micelle showed a particle size of 264.4 nm in aqueous solution. An in vitro release experiment demonstrated that the releasing rate of 6-MP from HA-SS-MP in the release medium containing glutathione (GSH) was much higher than that in the release medium without GSH. Cell uptake experiments demonstrated the CD44 targeting of hyaluronic acid. Cytotoxicity tests in mouse melanoma cells (B16F10) showed that HA-SS-MP can kill melanoma cells effectively and with lower cytotoxicity, compared with the active ingredient, 6-MP.

Glutathione-responsive nanoscale MOFs for effective intracellular delivery of the anticancer drug 6-mercaptopurine

A glutathione-responsive drug-delivery platform based on nanoMOFs was developed for selective cancer therapy through the introduction of disulfide bonds.

Evaluation of the Synergism Mechanism of Tamoxifen and Docetaxel by Nanoparticles

BACKGROUND

Our previous studies have shown that Docetaxel (DTX) and Tamoxifen (TMX) loaded nanoparticles(Co-NPs) could exhibit a synergistic effect on estrogen receptor positive cell lines. In the current study，we have studied the synergistic effect of Co-NPs and underlying possible molecular mechanism.

METHODS

Cell apoptosis assay, pharmacokinetic experiment and immunohistochemistry experiment were used to explore the synergistic effect and underlying possible mechanism in vitro and in vivo.

RESULTS

Cell apoptosis assay revealed that Co-NPs could mediate cell sensitization to a cytotoxic agent, resulting in remarkable cell apoptosis. In addition, pharmacokinetic experiment research showed that Co-NPs have longer circulation time in vivo, which could prolong the treatment time of the chemotherapeutic drugs. Immunohistochemistry experiment revealed that the Co-NPs could downregulate the expression of P-gp level to reduce the drugs' efflux.

CONCLUSION

The possible mechanism of the synergistic effect of DTX and TMX by Co-NPs was attributed to the longer in vivo circulation time, significantly increased rate of cell apoptosis and downregulated expression of P-gp level to the tumor cells.

Redox-Responsive Polymer with Self-Immolative Linkers for the Release of Payloads

Previous couplings of corrosion inhibitors to redox-responsive polymers via covalent bonding suffer from several drawbacks. It is presented here novel redox-responsive polymer-corrosion inhibitor conjugates that contain self-immolative linkers in their side chains. Very fast redox-induced release of tryptamine, a drug and a corrosion inhibitor, is observed after applying a reductive trigger.

Designing Smart Polymer Conjugates for Controlled Release of Payloads

Incorporating labile bonds inside polymer backbone and side chains yields interesting polymer materials that are responsive to change of environmental stimuli. Drugs can be conjugated to various polymers through different conjugation linkages and spacers. One of the key factors influencing the release profile of conjugated drugs is the hydrolytic stability of the conjugated linkage. Generally, the hydrolysis of acid-labile linkages, including acetal, imine, hydrazone, and to some extent β-thiopropionate, are relatively fast and the conjugated drug can be completely released in the range of several hours to a few days. The cleavage of ester linkages are usually slow, which is beneficial for continuous and prolonged release. Another key structural factor is the water solubility of polymer-drug conjugates. Generally, the release rate from highly water-soluble prodrugs is fast. In prodrugs with large hydrophobic segments, the hydrophobic drugs are usually located in the hydrophobic core of micelles and nanoparticles, which limits the access to the water, hence lowering significantly the hydrolysis rate. Finally, self-immolative polymers are also an intriguing new class of materials. New synthetic pathways are needed to overcome the fact that much of the small molecules produced upon degradation are not active molecules useful for biomedical applications.

Aminoglucose-functionalized, redox-responsive polymer nanomicelles for overcoming chemoresistance in lung cancer cells

Background

Chemotherapeutic drugs used for cancer therapy frequently encounter multiple-drug resistance (MDR). Nanoscale carriers that can target tumors to accumulate and release drugs intracellularly have the greatest potential for overcoming MDR. Glucose transporter-1 (GLUT-1) and glutathione (GSH) overexpression in cancer cells was exploited to assemble aminoglucose (AG)-conjugated, redox-responsive nanomicelles from a single disulfide bond-bridged block polymer of polyethylene glycol and polylactic acid (AG-PEG-SS-PLA). However, whether this dual functional vector can overcome MDR in lung cancer is unknown.

Results

In this experiment, AG-PEG-SS-PLA was synthetized successfully, and paclitaxel (PTX)-loaded AG-PEG-SS-PLA (AG-PEG-SS-PLA/PTX) nanomicelles exhibited excellent physical properties. These nanomicelles show enhanced tumor targeting as well as drug accumulation and retention in MDR cancer cells. Caveolin-dependent endocytosis is mainly responsible for nanomicelle internalization. After internalization, the disulfide bond of AG-PEG-SS-PLA is cleaved in the presence of high intracellular glutathione levels, causing the hydrophobic core to become a polar aqueous solution, which subsequently results in nanomicelle disassembly and the rapid release of encapsulated PTX. Reduced drug resistance was observed in cancer cells in vitro. The caspase-9 and caspase-3 cascade was activated by the AG-PEG-SS-PLA/PTX nanomicelles through upregulation of the pro-apoptotic proteins Bax and Bid and suppression of the anti-apoptotic protein Bcl-2, thereby increasing apoptosis. Furthermore, significantly enhanced tumor growth inhibition was observed in nude mice bearing A549/ADR xenograft tumors after the administration of AG-PEG-SS-PLA/PTX nanomicelles via tail injection.

Conclusions

These promising results indicate that AG-PEG-SS-PLA/PTX nanomicelles could provide the foundation for a paradigm shift in MDR cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s12951-017-0316-z) contains supplementary material, which is available to authorized users.

The reversion of anti-cancer drug antagonism of tamoxifen and docetaxel by the hyaluronic acid-decorated polymeric nanoparticles

Docetaxel (DTX) and tamoxifen (TMX) are first-line drugs used to treat breast cancer. However when used in combination, they produce antagonism because of their differential metabolic pathways. In order to prevent this antagonism, an amphiphilic copolymer, cholesterol modified hyaruronic acid (HA-CHOL), was synthesized for investigating the co-delivery of TMX and DTX. In vitro drug release experiment of the Co-encapsulated (encapsulated DTX+TMX) nanoparticles (Co-NPs) revealed that NPs with unique release mechanism can markedly reduce the release of these drugs in the circulatory system. However, when reaching in cell, TMX can release rapidly to prevent DTX from coming into contact with metabolizing enzymes. In vitro cytotoxicity experiment revealed that the Co-NPs exhibited a significant synergistic effect for inhibiting the proliferation of the cancer cell lines A549, MCF7 and S180. NPs carrying Coumarin-6(Cou6) exhibited increased cellular uptake compared with Cou6 solution at similar drug concentrations. As an in vivo treatment of xenograft tumors involving 180 cells, the Co-NPs displayed a clear tumor-inhibiting effect. This led us to conclude that the reversion of drug antagonism by NPs was attributed to the increased stability of the nanoparticles in the blood circulation, the efficient cellular uptake, the hierarchical drug metabolism in the tumor and the good and orderly delivery of the drugs to the tumor tissue.

Block ionomer micellar nanoparticles from double hydrophilic copolymers, classifications and promises for delivery of cancer chemotherapeutics

A class of double hydrophilic copolymers comprising ionic and nonionic water-soluble blocks, which are also called block ionomers, represent an interesting type of polymer assembly forming stable, homogeneous core-corona dispersions. They exhibit the solution behavior of normal polyelectrolytes, whereas assembly into micelle, vesicle or disk morphology happens by an external stimulus (pH, temperature or ionic strength) or complex formation with metal ions, ionic surfactants, polyelectrolytes, etc. Temperature, pH, redox or salt sensitivity affords a unique opportunity to control the triggered release of payloads accommodated through electrostatic interaction, coordination or chemical conjugation. Moreover, the non-ionic block provides the surface passivation, prolongation of the blood circulation and tumor accumulation, supporting targeted delivery of chemotherapeutic agents based on pathophysiology of tumor microenvironment. Potentiation of antitumor activity, sensitization of the resistant tumors, increased tolerated dose and translation into clinical practice are among their most intriguing characteristics. Their high functionality has been suggested for co-delivery of multiple agents for reversal of chemo-resistance as well as simultaneous therapy and diagnostics. Nevertheless, some stability concerns may be raised due to the polymer disassembly beyond a critical concentration of pH, salt and polyion concentration that can be modulated by introducing crosslinks between the polymer chains (Nano-networks).

In vitro–in vivo evaluation of hyaluronic acid-based amphiphilic copolymers for tumour targeted delivery: the role of hydrophobic groups

Polymeric micelles are widely used as suitable nano-carriers for a variety of therapeutic applications.

Ternary-responsive magnetic nanocarriers for targeted delivery of thiol-containing anticancer drugs

Cancer is currently the second leading cause of death in the world and one of the most serious challenges in medical therapy.

Cathepsin B-sensitive cholesteryl hemisuccinate–gemcitabine prodrug nanoparticles: enhanced cellular uptake and intracellular drug controlled release

Cholesteryl hemisuccinate–gemcitabine prodrug: enhanced cellular uptake and intracellular drug controlled release.

Smart branched polymer drug conjugates as nano-sized drug delivery systems

Branched polymers own special properties derived from their intrinsic characteristics. These properties make them ideal candidates to be used as carriers for an improved generation of polymer-drug conjugates.

Effects of the sol-gel route on the structural characteristics and antibacterial activity of silica-encapsulated gentamicin

The effects of sol-gel processes, i.e., acid-catalyzed gelation, base-catalyzed gelation and base-catalyzed precipitation routes, on the encapsulation of gentamicin were investigated. The resulting xerogels were characterized using a series of complementary instrumental techniques, i.e., the adsorption/desorption of nitrogen, small-angle X-ray scattering, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. The encapsulated gentamicin samples were tested against a series of Gram-positive and Gram-negative bacterial strains. The best antimicrobial activity was observed with the encapsulated gentamicin that was prepared via the precipitation route, even in comparison with the neat antibiotic, especially in the case of the Gram-positive strain Staphylococcus aureus. The gentamicin concentration on the outermost surface and the zeta potential were identified as factors that affected the highest efficiency, as observed in the case of encapsulation via the base-catalyzed process.

Nanocapsules based on mPEGylated artesunate prodrug and its cytotoxicity

mPEGylated artesunate prodrug was synthesized via esterification between poly(ethylene glycol) monomethyl ether (mPEG) and artesunate (ART). The product was inclined to form nanocapsules in aqueous media due to its amphiphilic nature. These nanocapsules showed narrow size distribution, with an average particle size of 88.7 nm measured by dynamic laser scattering (DLS). Their vesical morphology was further confirmed by transmission electron microscopy (TEM). We found that the release of ART from the nanocapsules was controllable, which was contributed to the easily hydrolyzed property of the ester bond. In addition, the cytotoxicity of the prodrug against L1210 and MCF7 cell lines showed an essential decrease compared with the free ART. These results present a new strategy in designing anti-tumor ART nanocapsules for targeting tumor cells.