Design of a new self-assembling antioxidant nanomedicine to ameliorate oxidative stress in zebrafish embryos

Development and evaluation of a self-assembled nanoparticle-based prodrug for sustained delivery of 4-phenylbutyric acid

4-Phenylbutyric acid (PBA) is a small molecule with promising therapeutic potential for treating various diseases, including cancer and neurodegenerative disorders, due to its dual ability to reduce endoplasmic reticulum stress and inhibit histone deacetylases. However, its clinical application is hindered by rapid clearance from the body, necessitating frequent dosing that increases the risk of adverse effects. To address these limitations, we developed a nanoparticle-based prodrug (NanoPBA) utilizing the amphiphilic block copolymer poly(ethylene glycol)-b-poly(vinyl 4-phenylbutyrate) [PEG-b-P(VPBA)]. This system self-assembles into micelles, enabling controlled and sustained PBA delivery. The synthesis and characterization of NanoPBA revealed its high stability under physiological conditions and enzyme-responsive PBA release. NanoPBA demonstrated a controlled release profile in vitro, reducing burst release while maintaining therapeutic efficacy. Cytotoxicity assays using normal cell lines, including endothelial cells (BAEC), macrophages (RAW264.7), and rat gastric cells (RGM-1), showed minimal cytotoxic effects compared to the parent low-molecular-weight PBA. Furthermore, in vivo studies conducted in healthy C57BL/6J mice confirmed NanoPBA's biocompatibility, with no significant adverse effects observed at therapeutic doses ranging from 200 to 500 mg-PBA/kg via oral administration. In conclusion, NanoPBA offers a controlled release profile, enhanced biocompatibility, and reduced toxicity, addressing the limitations associated with conventional PBA administration. These attributes make NanoPBA a promising candidate for improving the therapeutic efficacy and safety of PBA in clinical applications, particularly in diseases where maintaining consistent drug levels is crucial for treatment outcomes.

Delivery of Tempol from Polyurethane Nanocapsules to Address Oxidative Stress Post-Injury

Traumatic brain injuries (TBIs) result in significant morbidity and mortality due to the cascade of secondary injuries involving oxidative stress and neuroinflammation. The development of effective therapeutic strategies to mitigate these effects is critical. This study explores the fabrication and characterization of polyurethane nanocapsules for the sustained delivery of Tempol, a potent antioxidant. The nanocapsules were designed to extend the release of Tempol over a 30-day period, addressing the prolonged oxidative stress observed post-TBI. Tempol-loaded polyurethane nanocapsules were synthesized using interfacial polymerization and nanoemulsion techniques. Two generations of nanocapsules were produced, differing in Tempol loading and PEGylation levels. The first generation, with lower Tempol loading, exhibited an average size of 159.8 ± 12.61 nm and a Z-average diameter of 771.9 ± 87.95 nm. The second generation, with higher Tempol loading, showed an average size of 141.4 ± 6.13 nm and a Z-average diameter of 560.7 ± 171.1 nm. The zeta potentials were -18.9 ± 5.02 mV and -11.9 ± 3.54 mV for the first and second generations, respectively. Both generations demonstrated the presence of urethane linkages, confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Loading studies revealed Tempol concentrations of 61.94 ± 3.04 μg/mg for the first generation and 77.61 ± 3.04 μg/mg for the second generation nanocapsules. Release profiles indicated an initial burst followed by a sustained, nearly linear release over 30 days. The higher PEGylation in the second generation nanocapsules is advantageous for intravenous administration, potentially enhancing their therapeutic efficacy in TBI treatment. This study demonstrates the feasibility of using polyurethane nanocapsules for the prolonged delivery of Tempol, offering a promising approach to manage oxidative stress and improve outcomes in TBI patients. Future work will include testing these nanocapsules in vivo to determine their potential at modulating recovery from TBI.

Nitroxide-Containing Poly(2-oxazoline)s Show Dual-Stimuli-Responsive Behavior and Radical-Trapping Activity

2,2,6,6-Tetramethylpiperidine-N-oxyl (TEMPO) structures possess potent antioxidant activities for biomedical applications. TEMPO immobilization on hydrophilic polymers is a powerful strategy to improve its properties; however, it is mostly limited to reversible-deactivation radical polymerizations or postpolymerization approaches. Here, we immobilized TEMPO units on a hydrophilic poly(2-ethyl-2-oxazoline) (PEtOx) backbone through cationic ring-opening polymerization (CROP) of a new 2-oxazoline monomer bearing a methoxy-protected TEMPO 2-substituent with 2-ethyl-2-oxazoline (EtOx). The ratios of EtOx/TempOx were adjusted to optimize the nitroxide content while maintaining suitable water solubility of the resulting P(EtOxx-stat-TempOx-Oy•) copolymers upon deprotection. P(EtOx40-stat-TempOx-O10•) and P(EtOx33-stat-TempOx-O17•) showed a dual stimuli-responsive behavior and demonstrated significant radical-trapping activities in aqueous media. Particularly, a meaningful augmentation in the activity of TempOx-O• was observed when it was immobilized as P(EtOxx-stat-TempOx-Oy•). The P(EtOx40-stat-TempOx-O10•) system exhibited a longer-lasting activity in water, statistically comparable to that of the antioxidant ferrostatin-1 (Fer-1). Overall, this study introduces a biocompatible polymeric platform for TEMPO immobilization that augments its radical-trapping activity and offers controllable stimuli-responsive properties.

Sorafenib-Loaded Silica-Containing Redox Nanoparticle Decreases Tumorigenic Potential of Lewis Lung Carcinoma

Background: Orally administered sorafenib has shown limited improvement in overall survival for non-small-cell lung cancer patients, likely due to poor pharmacokinetics and adverse effects, including gastrointestinal toxicity. To address these issues, we developed silica-containing antioxidant nanoparticles (siRNP) as a carrier to enhance the therapeutic efficacy of lipophilic sorafenib. Methods: Sorafenib was loaded into siRNP via dialysis (sora@siRNP). The therapeutic efficacy and safety of sora@siRNP (20 and 40 mg-sora/kg) were evaluated in a xenograft mouse model of Lewis lung carcinoma (subcutaneous tumors and experimental metastasis) following oral administration. Results: Crosslinking nanosilica in siRNP improved drug stability, enabling 8.9% sorafenib loading and pH resilience. Oral sora@siRNP exhibited dose-dependent tumor growth suppression by downregulating pMEK, outperforming free sorafenib, which showed inconsistent efficacy likely due to formulation variability. Intestinal damage, a major adverse effect of free sorafenib, was significantly reduced with sora@siRNP, attributed to siRNP's antioxidant property of mitigating oxidative damage. Survival rates in the experimental metastasis model were 66-74% for sorafenib but reached 100% for sora@siRNP, highlighting its superior efficacy and safety. Conclusions: These findings demonstrate that nanosilica-crosslinked antioxidant nanoparticles (siRNP) enhance the stability, delivery efficiency, and safety of lipophilic drugs like sorafenib for oral administration. This platform holds promise for improving therapeutic outcomes in lung cancer while minimizing adverse effects.

The Cellular and Organismal Effects of Nitroxides and Nitroxide-Containing Nanoparticles

Nitroxides are stable free radicals that have antioxidant properties. They react with many types of radicals, including alkyl and peroxyl radicals. They act as mimics of superoxide dismutase and stimulate the catalase activity of hemoproteins. In some situations, they may exhibit pro-oxidant activity, mainly due to the formation of oxoammonium cations as products of their oxidation. In this review, the cellular effects of nitroxides and their effects in animal experiments and clinical trials are discussed, including the beneficial effects in various pathological situations involving oxidative stress, protective effects against UV and ionizing radiation, and prolongation of the life span of cancer-prone mice. Nitroxides were used as active components of various types of nanoparticles. The application of these nanoparticles in cellular and animal experiments is also discussed.