ROS-triggered and regenerating anticancer nanosystem: An effective strategy to subdue tumor's multidrug resistance

Control of biomedical nanoparticle distribution and drug release in vivo by complex particle design strategies

The utilization of targeted nanoparticles as a selective drug delivery system is a powerful tool to increase the amount of active substance reaching the target site. This can increase therapeutic efficacy while reducing adverse drug effects. However, nanoparticles face several challenges: upon injection, the immediate adhesion of plasma proteins may mask targeting ligands, thereby diminishing the target cell selectivity. In addition, opsonization can lead to premature clearance and the widespread presence of receptors or enzymes limits the accuracy of target cell recognition. Nanoparticles may also suffer from endosomal entrapment, and controlled drug release can be hindered by premature burst release or insufficient particle retention at the target site. Various strategies have been developed to address these adverse events, such as the implementation of switchable particle properties, regulating the composition of the formed protein corona, or using click-chemistry based targeting approaches. This has resulted in increasingly complex particle designs, raising the question of whether this development actually improves the therapeutic efficacy in vivo. This review provides an overview of the challenges in targeted drug delivery and explores potential solutions described in the literature. Subsequently, appropriate strategies for the development of nanoparticular drug delivery concepts are discussed.

Injectable pathological microenvironment-responsive anti-inflammatory hydrogels for ameliorating intervertebral disc degeneration

Chronic local inflammation and resulting cellular dysfunction of nucleus pulposus (NP) cells are important pathogenic factors of intervertebral disc degeneration (IDD). Injectable pathological microenvironment-responsive hydrogels hold significant potential for treating IDD by adapting to dynamic microenvironment of IDD. Herein, we proposed an injectable gelatin-based hydrogel drug delivery system that could respond to the pathological microenvironment of IDD for controlled release of anti-inflammatory drug to promote degenerative NP repair. The hydrogel system was prepared by conjugating phenylboronic acid-modified gelatin methacryloyl (GP) with the naturally extracted anti-inflammatory drug epigallocatechin-3-gallate (EGCG) through dynamic boronic esters. The hydrogel exhibited excellent degradability, injectability, antioxidant properties, anti-inflammatory effects, and biocompatibility. It also displayed responsive-release of EGCG under high reactive oxygen species (ROS) levels and acidic conditions. The hydrogel demonstrated remarkable cytoprotective effects on NP cells in both hyperactive ROS environments and inflammatory cytokine-overexpressed environments in vitro. In vivo studies revealed that the hydrogel injected in situ could effectively ameliorate the intervertebral disc degeneration by maintaining the disc height and NP tissue structure in a rat IDD model. The hydrogel system exhibited excellent biocompatibility and responsive-release of diol-containing drugs in pathological microenvironments, indicating its potential application as a drug delivery platform.

Preparation and In vitro Evaluation of Folated Pluronic F87/TPGS Co-modified Liposomes for Targeted Delivery of Curcumin

BACKGROUND

Using targeted liposomes to encapsulate and deliver drugs has become a hotspot in biomedical research. Folated Pluronic F87/D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) co-modified liposomes (FA-F87/TPGS-Lps) were fabricated for curcumin delivery, and intracellular targeting of liposomal curcumin was investigated.

METHODS

FA-F87 was synthesized and its structural characterization was conducted through dehydration condensation. Then, cur-FA-F87/TPGS-Lps were prepared via thin film dispersion method combined with DHPM technique, and their physicochemical properties and cytotoxicity were determined. Finally, the intracellular distribution of cur-FA-F87/TPGS-Lps was investigated using MCF-7 cells.

RESULTS

Incorporation of TPGS in liposomes reduced their particle size, but increased the negative charge of the liposomes as well as their storage stability, and the encapsulation efficiency of curcumin was improved. While, modification of liposomes with FA increased their particle size, and had no impact on the encapsulation efficiency of curcumin in liposomes. Among all the liposomes (cur-F87-Lps, cur-FA-F87-Lps, cur-FA-F87/TPGS-Lps and cur-F87/TPGS-Lps), cur-FA-F87/TPGS-Lps showed highest cytotoxicity to MCF-7 cells. Moreover, cur-FA-F87/TPGS-Lps was found to deliver curcumin into the cytoplasm of MCF-7 cells.

CONCLUSION

Folate-Pluronic F87/TPGS co-modified liposomes provide a novel strategy for drug loading and targeted delivery.

Jointly Depleting Glutathione Based on Self-Assembled Nanomicelles for Enhancing Photodynamic Therapy

Photodynamic therapy (PDT) is one common ROS-generating therapeutic method with high tumor selectivity and low side effects. But the GSH-upregulation often alleviates its therapeutic efficiency. Here, we proposed a new strategy of jointly depleting GSH to enhance the therapeutic effect of PDT by preparing a nanomicelle by self-assembly method from GSH-activated photosensitizer DMT, curcumin, and amphiphilic polymer TPGS.

The Application of Biomedicine in Chemodynamic Therapy: From Material Design to Improved Strategies

Chemodynamic therapy (CDT) has garnered significant interest as an innovative approach for cancer treatment, owing to its notable tumor specificity and selectivity, minimal systemic toxicity and side effects, and absence of the requirement for field stimulation during treatment. This treatment utilizes nanocatalytic medicines containing transitional metals to release metal ions within tumor cells, subsequently initiating Fenton and Fenton-like reactions. These reactions convert hydrogen peroxide (H2O2) into hydroxyl radical (•OH) specifically within the acidic tumor microenvironment (TME), thereby inducing apoptosis in tumor cells. However, insufficient endogenous H2O2, the overexpressed reducing substances in the TME, and the weak acidity of solid tumors limit the performance of CDT and restrict its application in vivo. Therefore, a variety of nanozymes and strategies have been designed and developed in order to potentiate CDT against tumors, including the application of various nanozymes and different strategies to remodel TME for enhanced CDT (e.g., increasing the H2O2 level in situ, depleting reductive substances, and lowering the pH value). This review presents an overview of the design and development of various nanocatalysts and the corresponding strategies employed to enhance catalytic drug targeting in recent years. Additionally, it delves into the prospects and obstacles that lie ahead for the future advancement of CDT.

cRGD-modified nanoparticles of multi-bioactive agent conjugate with pH-sensitive linkers and PD-L1 antagonist for integrative collaborative treatment of breast cancer

Targeted co-delivery and co-release of multi-drugs is essential to have an integrative collaborative effect on treating cancer. It is valuable to use few drug carriers for multi-drug delivery. Herein, we develop cRGD-modified nanoparticles (cRGD-TDA) of a conjugate of doxorubicin as cytotoxic agent, adjudin as an anti-metastasis agent and D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) as a reactive oxygen species inducer linked with pH-sensitive bonds, and then combine the nanoparticles with PD-L1 antagonist to treat 4T1 triple-negative breast cancer. cRGD-TDA NPs present tumor-targeted co-delivery and pH-sensitive co-release of triple agents. cRGD-TDA NPs combined with PD-L1 antagonist much more significantly inhibit tumor growth and metastasis than single-drug treatment, which is due to their integrative collaborative effect. It is found that TPGS elicits a powerful immunogenic cell death effect. Meanwhile, PD-L1 antagonist mitigates the immunosuppressive environment and has a synergistic effect with the cRGD-TDA NPs. The study provides a new strategy to treat refractory cancer integratively and collaboratively.

TPGS Decorated Liposomes as Multifunctional Nano-Delivery Systems

Liposomes are sphere-shaped vesicles that can capture therapeutics either in the outer phospholipid bilayer or inner aqueous core. Liposomes, especially when surface-modified with functional materials, have been used to achieve many benefits in drug delivery, including improving drug solubility, oral bioavailability, pharmacokinetics, and delivery to disease target sites such as cancers. Among the functional materials used to modify the surface of liposomes, the FDA-approved non-ionic surfactant D-alpha-tocopheryl polyethylene glycol succinate (TPGS) is increasingly being applied due to its biocompatibility, lack of toxicity, applicability to various administration routes and ability to enhance solubilization, stability, penetration and overall pharmacokinetics. TPGS decorated liposomes are emerging as a promising drug delivery system for various diseases and are expected to enter the market in the coming years. In this review article, we focus on the multifunctional properties of TPGS-coated liposomes and their beneficial therapeutic applications, including for oral drug delivery, vaccine delivery, ocular administration, and the treatment of various cancers. We also suggest future directions to optimise the manufacture and performance of TPGS liposomes and, thus, the delivery and effect of encapsulated diagnostics and therapeutics.

Redox homeostasis modulation using theranostic AIE nanoparticles results in positive-feedback drug accumulation and enhanced drug penetration to combat drug-resistant cancer

Drug-resistant cancers usually have multiple barriers to compromise the effect of therapies, of which multidrug-resistance (MDR) phenotype as the intracellular barrier and dense tumor matrix as the extracellular barrier, significantly contribute to the poor anticancer performance of current drug delivery systems (DDS). Here in this study, we fabricated a novel aggregation-induced emission (AIE)-active polymer capable of self-assembling into ultrasmall nanoparticles (∼20 ​nm) with D-alpha Tocopheryl Polyethylene Glycol Succinate (TPGS), for dual-encapsulating of doxorubicin (Dox) and sulforaphane (SFN) (AT/Dox/SFN). It revealed that redox homeostasis modulation of MDR cells (MCF-7/Adr) using AT/Dox/SFN can trigger mitochondria damage and ATP deficiency, which reverse the MDR phenotype of MCF-7/Adr cells to afford enhanced cellular uptake of both drug and DDS in a positive-feedback manner. The enhanced cellular drug accumulation further initiates the “neighboring effect” for improved drug penetration. Using this strategy, the growth of in vivo MCF-7/Adr tumors can be effectively inhibited at a low dosage (1/5) of doxorubicin (Dox) as compared to free Dox. In summary, we offer a new approach to overcome both the intracellular and extracellular barriers of drug-resistant cancers and elucidate the potential action mechanisms, which are beneficial for better cancer management.

•

Redox homeostasis modulation in MDR cancer cell results in positive-feedback drug accumulation and enhanced drug penetration.

•

Mitochondria damage and neighboring effect is responsible for MDR reversal and enhanced drug penetration, respectively.

•

AT/Dox/SFN effectively inhibits ​in vivo ​MCF-7/Adr tumors at a low dosage (1/5) of doxorubicin (Dox) as compared to free Dox.

Self-amplified ROS-responsive chemodrug-inhibitor conjugate for multi-drug resistance tumor therapy

P-glycoprotein (P-gp) overexpression caused multidrug resistance (MDR) is a main reason for the failure of cancer chemotherapy. The combined delivery of chemodrug and P-gp inhibitor is a promising pathway to...

Traditional herbal medicine and nanomedicine: Converging disciplines to improve therapeutic efficacy and human health

Traditional herbal medicine (THM), an ancient science, is a gift from nature. For thousands of years, it has helped humans fight diseases and protect life, health, and reproduction. Nanomedicine, a newer discipline has evolved from exploitation of the unique nanoscale morphology and is widely used in diagnosis, imaging, drug delivery, and other biomedical fields. Although THM and nanomedicine differ greatly in time span and discipline dimensions, they are closely related and are even evolving toward integration and convergence. This review begins with the history and latest research progress of THM and nanomedicine, expounding their respective developmental trajectory. It then discusses the overlapping connectivity and relevance of the two fields, including nanoaggregates generated in herbal medicine decoctions, the application of nanotechnology in the delivery and treatment of natural active ingredients, and the influence of physiological regulatory capability of THM on the in vivo fate of nanoparticles. Finally, future development trends, challenges, and research directions are discussed.

Recent advances in polymeric core-shell nanocarriers for targeted delivery of chemotherapeutic drugs

The treatment effect of chemotherapeutics is often impeded by nonspecific biodistribution and limited biocompatibility. Polymeric core-shell nanocarriers (PCS NCs) composed of a polymer core and at least one shell have been widely applied for cancer therapy and have shown great potential in selectively delivering chemotherapeutic drugs to tumor sites. These PCS NCs can effectively ameliorate the delivery efficiency and therapeutic index of anticarcinogens by prolonging drug residence in the bloodstream, enhancing tumor tissue drug penetration, facilitating cellular drug uptake, controlling the spatiotemporal release of payloads, or codelivering two or more bioactive agents. This review summarizes recently published literature on using PCS NCs to transport chemotherapeutic drugs with poor aqueous solubility and discusses their design principles, structural features, functional properties, and potential limitations.

Exosome-eluting stents for vascular healing after ischaemic injury

Drug-eluting stents implanted after ischaemic injury reduce the proliferation of endothelial cells and vascular smooth muscle cells and thus neointimal hyperplasia. However, the eluted drug also slows down the re-endothelialization process, delays arterial healing and can increase the risk of late restenosis. Here we show that stents releasing exosomes derived from mesenchymal stem cells in the presence of reactive oxygen species enhance vascular healing in rats with renal ischaemia-reperfusion injury, promoting endothelial cell tube formation and proliferation, and impairing the migration of smooth muscle cells. Compared with drug-eluting stents and bare-metal stents, the exosome-coated stents accelerated re-endothelialization and decreased in-stent restenosis 28 days after implantation. We also show that exosome-eluting stents implanted in the abdominal aorta of rats with unilateral hindlimb ischaemia regulated macrophage polarization, reduced local vascular and systemic inflammation, and promoted muscle tissue repair.

pH/ROS dual-sensitive and chondroitin sulfate wrapped poly (β-amino ester)-SA-PAPE copolymer nanoparticles for macrophage-targeted oral therapy for ulcerative colitis

An oral nanoparticle (NPs) encapsulated in chitosan/alginate hydrogel (CA-Gel) with dual-sensitive in pH and reactive oxygen species (ROS) was developed to load curcumin (CUR) based on the intracellular-specific characteristics of macrophages. Chondroitin sulfate (CS) wrapped PBAE-SA-PAPE with intracellular pH/ROS dual-sensitive characteristics and CUR via a simple nanoprecipitation method to form NPs (CS-CUR-NPs), and mixed CA-Gel to acquire the final preparation (CS-CUR-NPs-Gel). CS-CUR-NPs displayed an ideal average particle size (179.19±5.61nm) and high encapsulating efficiency (94.74±1.15%). CS showed a good targeting ability on macrophages and the CA-Gel contribution in protecting NPs from being destroyed in the upper gastrointestinal tract. As expected, CS-CUR-NPs-Gel could significantly alleviate inflammation in DSS-induced UC mice via TLR4-MAPK/NF-κB pathway. This study is the first to attempt to design a novel pH/ROS dual-stimulated release strategy in helping intracellular CUR delivery and anticipated for efficient anti-UC therapy.

Recent Advances in ROS-Sensitive Nano-Formulations for Atherosclerosis Applications

Over the past decade, ROS-sensitive formulations have been widely used in atherosclerosis applications such as ROS scavenging, drug delivery, gene delivery, and imaging. The intensified interest in ROS-sensitive formulations is attributed to their unique self-adaptive properties, involving the main molecular mechanisms of solubility switch and degradation under the pathological ROS differences in atherosclerosis. This review outlines the advances in the use of ROS-sensitive formulations in atherosclerosis applications during the past decade, especially highlighting the general design requirements in relation to biomedical functional performance.

ROS-Responsive Selenium-Containing Carriers for Coencapsulation of Photosensitizer and Hypoxia-Activated Prodrug and Their Cellular Behaviors

The integration of hypoxia-activated chemotherapy with photodynamic therapy (PDT) has newly become a potent strategy for tumor treatment. Herein, a reactive oxygen species (ROS)-responsive drug carriers (PS@AQ4N/mPEG-b-PSe NPs) are fabricated based on the amphiphilic selenium-containing methoxy poly(ethylene glycol)-polycarbonate (mPEG-b-PSe), the hydrophobic photosensitizer (PS), and hypoxia-activated prodrug Banoxantrone (AQ4N). The obtained nanoparticles are spherical with an average diameter of 100 nm as characterized by transmission electron microscope (TEM) and dynamic laser scattering (DLS) respectively. The encapsulation efficiency of the PS and AQ4N reaches 92.83% and 51.04% at different conditions, respectively, by UV-vis spectrophotometer. It is found that the drug release is accelerated due to the good ROS responsiveness of mPEG-b-PSe and the cumulative release of AQ4N is up to 89% within 30 h. The cell test demonstrates that the nanoparticles dissociate when triggered by the ROS stimuli in the cancer cells, thus the PS is exposed to more oxygen and the ROS generation efficiency is enhanced accordingly. The consumption of oxygen during PDT leads to the increased tumor hypoxia, and subsequently activates AQ4N into cytotoxic counterpart to inhibit tumor growth. Therefore, the synergistic therapeutic efficacy demonstrates this drug delivery has great potential for antitumor therapy.

Nanoengineering of a newly designed chlorin e6 derivative for amplified photodynamic therapy via regulating lactate metabolism

Chlorin e6 (Ce6) is a widely utilized photosensitizer in photodynamic therapy (PDT) against tumor growth, but its hydrophobic feature and the hypoxia in the tumor microenvironment greatly compromise its therapeutic efficacy. To address the issues, here we designed a new Ce6 derivative (TCe6) by coupling Ce6 with amphiphilic d-α-tocopherol polyethylene glycol 1000 succinate (TPGS), endowing Ce6 with an excellent amphiphilic feature. In particular, the overall reactive oxygen species (ROS) generation by TCe6 was significantly enhanced because TPGS could interact with mitochondrial complex II to induce extra ROS production, amplifying the total ROS production under PDT. Inspired by the unique property of α-cyano-4-hydroxycinnamate (CHC) in regulating lactate metabolism to spare more intracellular oxygen for PDT, TCe6 was further co-assembled with CHC to construct TCe6/CHC nanoparticles (NPs) for addressing the insufficient oxygen issue in PDT. The as-prepared TCe6/CHC NPs not only increased the efficiency of cell internalization but also improved the solubility and stability of Ce6 and CHC. Thanks to the extra ROS production by the TPGS unit, the amphiphilic feature of TCe6 and the CHC-mediated hypoxia microenvironment, the TCe6/CHC NPs demonstrated excellent PDT against tumor growth. This work provided a versatile strategy to solve the current bottleneck in photosensitizer-based PDT, holding great promise for the design of advanced photodynamic nanoplatforms.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

Ultrasound-enhanced fluorescence imaging and chemotherapy of multidrug-resistant tumors using multifunctional dendrimer/carbon dot nanohybrids

Development of innovative nanomedicine enabling enhanced theranostics of multidrug-resistant (MDR) tumors remains to be challenging. Herein, we report the development of a newly designed multifunctional yellow-fluorescent carbon dot (y-CD)/dendrimer nanohybrids as a platform for ultrasound (US)-enhanced fluorescence imaging and chemotherapy of MDR tumors. Generation 5 (G5) poly(amidoamine) dendrimers covalently modified with efflux inhibitor of d-α-tocopheryl polyethylene glycol 1000 succinate (G5-TPGS) were complexed with one-step hydrothermally synthesized y-CDs via electrostatic interaction. The formed G5-TPGS@y-CDs complexes were then physically loaded with anticancer drug doxorubicin (DOX) to generate (G5-TPGS@y-CDs)-DOX complexes. The developed nanohybrids display a high drug loading efficiency (40.7%), strong y-CD-induced fluorescence emission, and tumor microenvironment pH-preferred DOX release profile. Attributing to the DOX/TPGS dual drug design, the (G5-TPGS@y-CDs)-DOX complexes can overcome the multidrug resistance (MDR) of cancer cells and effectively inhibit the growth of cancer cells and tumors. Furthermore, the introduction of US-targeted microbubble destruction technology was proven to render the complexes with enhanced intracellular uptake and anticancer efficacy in vitro and improved chemotherapeutic efficacy and fluorescence imaging of tumors in vivo due to the produced sonoporation effect. The developed multifunctional dendrimer/CD nanohybrids may represent an advanced design of nanomedicine for US-enhanced theranostics of different types of MDR tumors.

CD44 Targeted Nanomaterials for Treatment of Triple-Negative Breast Cancer

Identified as the second leading cause of cancer-related deaths among American women after lung cancer, breast cancer of all types has been the focus of numerous research studies. Even though triple-negative breast cancer (TNBC) represents 15-20% of the number of breast cancer cases worldwide, its existing therapeutic options are fairly limited. Due to the pivotal role of the presence/absence of specific receptors to luminal A, luminal B, HER-2+, and TNBC in the molecular classification of breast cancer, the lack of these receptors has accounted for the aforementioned limitation. Thereupon, in an attempt to participate in the ongoing research endeavors to overcome such a limitation, the conducted study adopts a combination strategy as a therapeutic paradigm for TNBC, which has proven notable results with respect to both: improving patient outcomes and survivability rates. The study hinges upon an investigation of a promising NPs platform for CD44 mediated theranostic that can be combined with JAK/STAT inhibitors for the treatment of TNBC. The ability of momelotinib (MMB), which is a JAK/STAT inhibitor, to sensitize the TNBC to apoptosis inducer (CFM-4.16) has been evaluated in MDA-MB-231 and MDA-MB-468. MMB + CFM-4.16 combination with a combination index (CI) ≤0.5, has been selected for in vitro and in vivo studies. MMB has been combined with CD44 directed polymeric nanoparticles (PNPs) loaded with CFM-4.16, namely CD44-T-PNPs, which selectively delivered the payload to CD44 overexpressing TNBC with a significant decrease in cell viability associated with a high dose reduction index (DRI). The mechanism underlying their synergism is based on the simultaneous downregulation of P-STAT3 and the up-regulation of CARP-1, which has induced ROS-dependent apoptosis leading to caspase 3/7 elevation, cell shrinkage, DNA damage, and suppressed migration. CD44-T-PNPs showed a remarkable cellular internalization, demonstrated by uptake of a Rhodamine B dye in vitro and S0456 (NIR dye) in vivo. S0456 was conjugated to PNPs to form CD44-T-PNPs/S0456 that simultaneously delivered CFM-4.16 and S0456 parenterally with selective tumor targeting, prolonged circulation, minimized off-target distribution.

Selective antitumor activity of drug-free TPGS nanomicelles with ROS-induced mitochondrial cell death

D-a-tocopheryl polyethylene glycol succinate (TPGS) as a FDA-approved safe adjuvant has shown an excellent application in the targeting delivery of antitumor drugs and overcoming multidrug resistance. Beside, TPGS can result in apoptogenic activity toward many tumor types because it can induce mitochondrial dysfunction. Therefore, TPGS can serve as an antineoplastic agent. However, the current research on the selective antitumor activity of TPGS is ignored. To reveal the issue, herein we develop a mitochondria-targeting drug-free TPGS nanomicelles with the hydrodynamic diameter of about 100 nm and outstanding serum stability by weak interaction-driven self-assembly of the amphiphilic TPGS polymer. Moreover, such drug-free TPGS nanomicelles intravenously injected into tumor-bearing mice exhibit long blood circulation time, superior tumor enrichment, and inhibit the tumor growth via inducing excessive reactive oxygen species (ROS) generation within tumor cells. Further in vitro and in vivo researches jointly demonstrate that drug-free TPGS nanomicelles have more significant antitumor effect on HeLa cells compared with that of other tumor cells. On the contrary, drug-free TPGS nanomicelles display the low toxicity toward normal cells and tissues. Taken together, these new findings confirm that TPGS drug-free nanomicelles represent simple, multifunctional, safe, and efficient antineoplastic agents, which can be expected to bring new light on the development of drug-free polymers for tumor therapy.

Design Strategies and Applications of ROS-Responsive Phenylborate Ester-Based Nanomedicine

Reactive oxygen species (ROS)-responsive nanomedicine has been extensively developed to improve the therapeutic effects while reducing the systemic toxicity. ROS, as important biological metabolites and signaling molecules, are known to overexpress in most of tumors and inflammations. Among various ROS-sensitive moieties, phenylborate ester (PBAE) with easy modifiable structure and excellent biocompatibility, represents one of the most ROS-sensitive structures. To harness it as a switch, the past several years had witnessed a booming of ROS-sensitive PBAE-based nanomedicine for various medical purposes. Much of the efforts were devoted to exploiting the potential in the management of antitumor and anti-inflammation. This review first summarizes the design strategies of PBAE in the construction of nanomedicine, with PBAE acting as not only the ROS-responsive unit, but also the roles of hydrophobic backbone or bridging segment in the macromolecular structures. The ROS-responsive mechanisms are then briefly discussed. Afterward, we focus on the introduction of the state-of-the-art research on ROS-responsive PBAE-based nanomedicine for antitumor and anti-inflammation applications. The conclusion and future perspectives of ROS-responsive nanomedicine are also provided.

ROS-initiated chemiluminescence-driven payload release from macrocycle-based Azo-containing polymer nanocapsules

Reactive oxygen species (ROS) overproduction is involved in many pathological processes, particularly in inflammatory diseases. Therefore, ROS-responsive nanocarriers for specific drug release have been highly sought after. Herein we developed a ROS-responsive drug delivery system based on covalently self-assembled polymer nanocapsules (Azo-NCs) formed via crosslinking macrocyclic cucurbit[6]urils by a photo-sensitive azobenzene derivative (Azo). Luminol, a chemiluminescent molecule activatable by ROS, was co-loaded into Azo-NCs together with a therapeutic payload. When exposed to high ROS concentration that is typically encountered in inflammatory cells or tissues, the ROS-initiated blue chemiluminescence of luminol drives photoisomerization of the Azo groups within Azo-NCs, leading to Azo-NCs' surface transformation and distortion of the nanostructure, and subsequent payload release. As a proof-of-concept, ROS-responsive payload release from luminol-loaded Azo-NCs in inflammatory cells and zebrafish was demonstrated, showing promising anti-inflammatory effects in vitro and in vivo.

Reactive oxygen species-sensitive nanophotosensitizers of aminophenyl boronic acid pinacol ester conjugated chitosan-g-methoxy poly(ethylene glycol) copolymer for photodynamic treatment of cancer

The aim of this study is to prepare reactive oxygen species (ROS)-sensitive nanophotosensitizers for targeted delivery of chlorin e6 (Ce6) and photodynamic tumor therapy. For this purpose, thiodipropionic acid (TDPA) was conjugated with phenyl boronic acid pinacol ester (PBAP) (TDPA-PBAP conjugates) and then the TDPA-PBAP conjugates were attached to the chitosan backbone of chitosan-g-methoxy poly(ethylene glycol) (ChitoPEG) copolymer (ChitoPEG-PBAP). Ce6-incorporated ChitoPEG-PBAP nanophotosensitizers have an ROS-sensitive manner in vitro. The size of ChitoPEG-PBAP nanoparticles increased or disintegrated in a responsive manner against H2O2 concentration. The Ce6 release rate from ChitoPEG-PBAP nanophotosensitizers also increased by adding H2O2. These results indicated that nanophotosensitizers have sensitivity against ROS and showed triggered Ce6 release behavior. ChitoPEG-PBAP nanophotosensitizers can be more efficiently internalized into cancer cells compared to Ce6 alone and then produce ROS in a more efficient manner. Furthermore, ChitoPEG-PBAP nanophotosensitizers suppressed the viability of cancer cells in vitro and tumor growth in vivo with higher efficacy compared to Ce6 alone. Furthermore, ChitoPEG-PBAP nanophotosensitizers were efficiently delivered to irradiated tumor tissues, indicating that ChitoPEG-PBAP nanophotosensitizers can be delivered to the tumor with ROS-sensitive manner. We suggest that a ChitoPEG-PBAP nanophotosensitizer is a promising candidate for photodynamic therapy of cancers.

Lipid/Hyaluronic Acid-Coated Doxorubicin-Fe3O4 as a Dual-Targeting Nanoparticle for Enhanced Cancer Therapy

Development of a delivery system to lower systemic toxicity and enhance doxorubicin (DOX) antitumor efficacy against multi-drug resistant (MDR) tumors is of great clinical significance. Here, lipid/hyaluronic acid (HA)-coated DOX-Fe₃O₄ was characterized to determine its optimal safety and efficacy on a tumor. DOX was first conjugated onto the Fe₃O₄ NPs surface, which was subsequently coated with phosphatidylcholine (PC) lipids, which consisted of a tumor cell-targeting HA ligand, to generate a dual-targeting nanoparticle (NP). DOX-Fe₃O₄ synthesis was validated by the Fourier-transform infrared (FT-IR) analysis results. Core-shell PC/HA@DOX-Fe₃O₄ formation, which had an average particle size of 48.2 nm, was observed based on the transmission electron microscopy (TEM) and dynamic laser light scattering (DLS) results. The saturation magnetization value of PC/HA@DOX-Fe₃O₄ was discovered to be 28 emu/g using vibrating-sample magnetometry. Furthermore, the designed PC/HA@DOX-Fe₃O₄ achieved greater MCF-7/ADR cellular uptake and cytotoxicity as compared with DOX. In addition, PC/HA@DOX-Fe₃O₄ exhibited significant DOX tumor-targeting capabilities and enhanced tumor growth inhibition activity in the xenograft MCF-7/ADR tumor-bearing nude mice following magnetic attraction and ligand-mediated targeting, with less cardiotoxicity. Therefore, PC/HA@DOX-Fe₃O₄ is a potential candidate for MDR tumor chemotherapy. Graphical abstract.

Stimuli-Responsive Biomaterials for Vaccines and Immunotherapeutic Applications

The immune system is the key target for vaccines and immunotherapeutic approaches aimed at blunting infectious diseases, cancer, autoimmunity, and implant rejection. However, systemwide immunomodulation is undesirable due to the severe side effects that typically accompany such strategies. In order to circumvent these undesired, harmful effects, scientists have turned to tailorable biomaterials that can achieve localized, potent release of immune-modulating agents. Specifically, "stimuli-responsive" biomaterials hold a strong promise for delivery of immunotherapeutic agents to the disease site or disease-relevant tissues with high spatial and temporal accuracy. This review provides an overview of stimuli-responsive biomaterials used for targeted immunomodulation. Stimuli-responsive or "environmentally responsive" materials are customized to specifically react to changes in pH, temperature, enzymes, redox environment, photo-stimulation, molecule-binding, magnetic fields, ultrasound-stimulation, and electric fields. Moreover, the latest generation of this class of materials incorporates elements that allow for response to multiple stimuli. These developments, and other stimuli-responsive materials that are on the horizon, are discussed in the context of controlling immune responses.

Recent Advances of D-α-tocopherol Polyethylene Glycol 1000 Succinate Based Stimuli-responsive Nanomedicine for Cancer Treatment

D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) is a pharmaceutical excipient approved by Chinese NMPA and FDA of USA. It's widely applied as a multifunctional drug carrier for nanomedicine. The advantages of TPGS include P-glycoprotein (P-gp) inhibition, penetration promotion, apoptosis induction via mitochondrial-associated apoptotic pathways, multidrug resistant (MDR) reversion, metastasis inhibition and so on. TPGS-based drug delivery systems which are responding to external stimulus can combine the inhibitory functions of TPGS towards P-gp with the environmentally responsive controlled release property and thus exerts a synergistic anti-cancer effect, through increased intracellular drug concentration in tumors cells and well-controlled drug release behavior. In this review, TPGS-based nano-sized delivery systems responsive to different stimuli were summarized and discussed, including pH-responsive, redoxresponsive and multi-responsive systems in various formulations. The achievements, mechanisms and different characteristics of TPGS-based stimuli-responsive drug-delivery systems in tumor therapy were also outlined.

Reduction/Oxidation-Responsive Hierarchical Nanoparticles with Self-Driven Degradability for Enhanced Tumor Penetration and Precise Chemotherapy

Deep tumor penetration, long blood circulation, rapid drug release, and sufficient stability are the most concerning dilemmas of nano-drug-delivery systems for efficient chemotherapy. Herein, we develop reduction/oxidation-responsive hierarchical nanoparticles co-encapsulating paclitaxel (PTX) and pH-stimulated hyaluronidase (pSH) to surmount the sequential biological barriers for precise cancer therapy. Poly(ethylene glycol) diamine (PEG-dia) is applied to collaboratively cross-link the shell of nanoparticles self-assembled by a hyaluronic acid-stearic acid conjugate linked via a disulfide bond (HA-SS-SA, HSS) to fabricate the hierarchical nanoparticles (PHSS). The PTX and pSH coloaded hierarchical nanoparticles (PTX/pSH-PHSS) enhance the stability in normal physiological conditions and accelerate drug release at tumorous pH, and highly reductive or oxidative environments. Functionalized with PEG and HA, the hierarchical nanoparticles preferentially prolong the circulation time, accumulate at the tumor site, and enter MDA-MB-231 cells via CD44-mediated endocytosis. Within the acidic tumor micro-environment, pSH would be partially reactivated to decompose the dense tumor extracellular matrix for deep tumor penetration. Interestingly, PTX/pSH-PHSS could be degraded apace by the completely activated pSH within endo/lysosomes and the intracellular redox micro-environment to facilitate drug release to produce the highest tumor inhibition (93.71%) in breast cancer models.

Combination Therapy of Doxorubicin and Quercetin on Multidrug-Resistant Breast Cancer and Their Sequential Delivery by Reduction-Sensitive Hyaluronic Acid-Based Conjugate/d-α-Tocopheryl Poly(ethylene glycol) 1000 Succinate Mixed Micelles

The therapeutic efficacy of chemotherapy in many types of hematological malignancies and solid tumors is dramatically hindered by multidrug resistance (MDR). This work presents a combination strategy of pretreatment of MDA-MB-231/MDR1 cells with quercetin (QU) followed by doxorubicin (DOX) to overcome MDR, which can be delivered by mixed micelles composed of the reduction-sensitive hyaluronic acid-based conjugate and d-α-tocopheryl poly(ethylene glycol) 1000 succinate. The combination strategy can enhance the cytotoxicity of DOX on MDA-MB-231/MDR1 cells by increasing intracellular DOX accumulation and facilitating DOX-induced apoptosis. The probable MDR reversal mechanisms are that the pretreatment cells with QU-loaded mixed micelles downregulate P-glycoprotein expression to decrease DOX efflux as well as initiate mitochondria-dependent apoptotic pathways to accelerate DOX-induced apoptosis. In addition, this combination strategy can not only potentiate in vivo tumor-targeting efficiency but also enhance the antitumor effect in MDA-MB-231/MDR1-bearing nude mice without toxicity or side effects. This research suggests that the co-administration of natural compounds and chemotherapeutic drugs could be an effective strategy to overcome tumor MDR, which deserves further exploration.

A polymer coated MNP scaffold for targeted drug delivery and improvement of rheumatoid arthritis

DHAA–Fe₃O₄@HA as a nano-carrier was synthesized for targeted sulfasalazine delivery in specific inflammatory joint tissues with improvement in RA disease.

Reduced Toxicity of Liposomal Nitrogen Mustard Prodrug Formulation Activated by an Intracellular ROS Feedback Mechanism in Hematological Neoplasm Models

Nitrogen mustard (NM) is among the earliest drugs used to treat malignant tumors and it kills tumor cells by cross-linking DNA. Unfortunately, because of the short half-life and unfavorable selectivity, NM causes significant damage to normal tissues. As NM can increase the levels of reactive oxygen species (ROS) in tumor cells, a ROS-activated nitrogen mustard prodrug (NM-Pro) was synthesized and mixed with NM at a specific ratio to obtain an "NM-ROS-NM-Pro-NM" positive feedback system, which ultimately achieves a specific lethal effect on hematological neoplasms. The further encapsulation of NM/NM-Pro in liposomes allows the sustained release of the drug and prolongs the residence time in vivo. Here, we prepared stable liposomes with a uniform particle size of 170.6 ± 2.2 nm. The optimal ratio of NM to NM-Pro in this study was 2:1. The active drug NM in the NM/NM-Pro system continuously stimulated ROS production by the cells, which in turn further activated the NM-Pro to continuously generate NM. The positive feedback pathway between the NM and NM-Pro resulted in the specific death of tumor cells. Furthermore, the K562 hematological neoplasm model was utilized to evaluate the therapeutic effect of NM/NM-Pro liposomes in vivo. After encapsulation in liposomes, the targeting of tumor cells was increased approximately two times compared with that of normal cells, and NM/NM-Pro liposomes exhibited reduced toxicity, without an increase in drug activity compared to the NM/NM-Pro combination. The NM/NM-Pro delivery system exerts a positive feedback effect on ROS production in tumor cells and displays good potential for the specific killing of hematoma cells.

Facile Synthesis of a H2O2-Responsive Alternating Copolymer Bearing Thioether Side Groups for Drug Delivery and Controlled Release

A novel amphiphilic alternating copolymer with thioether side groups (P(MSPA-a-EG)) was synthesized through an amine-epoxy click reaction of 3-(methylthio)propylamine (MSPA) and ethylene glycol diglycidyl ether. P(MSPA-a-EG) was characterized in detail by nuclear magnetic resonance (NMR), gel permeation chromatography, Fourier transformed infrared, differential scanning calorimeter, and thermogravimetric analysis to confirm the successful synthesis. Due to its amphiphilic structure, P(MSPA-a-EG) could self-assemble into spherical micelles with an average diameter of about 151 nm. As triggered by H2O2, theses micelles could disassemble because hydrophobic thioether groups are transformed to hydrophilic sulfoxide groups in MSPA units. The oxidant disassemble process of micelles was systemically studied by dynamic light scattering, transmission electron microscopy, and 1H NMR measurements. The MTT assay against NIH/3T3 cells indicated that P(MSPA-a-EG) micelles exhibited good biocompatibility. Furthermore, they could be used as smart drug carriers to encapsulate hydrophobic anticancer drug doxorubicin (DOX) with 4.90% drug loading content and 9.81% drug loading efficiency. In vitro evaluation results indicated that the loaded DOX could be released rapidly, triggered by H2O2. Therefore, such a novel alternating copolymer was expected to be promising candidates for controlled drug delivery and release.

A ROS-responsive polymeric prodrug nanosystem with self-amplified drug release for PSMA (-) prostate cancer specific therapy

BACKGROUND

The selectively accumulate in tumor site and completely release drug within cancer cells great limit the therapeutic effect of nano-drug delivery system. Moreover, absence of appropriate biomarker is one of the major challenges for prostate specific membrane antigen negative (PSMA (-)) prostate cancer therapy.

RESULTS

Herein, a PSMA (-) prostate cancer specific targeted and intracellular reactive oxygen species (ROS) amplification for ROS-responsive self-accelerating drug release nanoplatform (ATD-NPs) was developed. ATD-NPs was formed by three parts, including PSMA (-) prostate cancer specifically targeted part (DUP-PEG-DSPE), ROS-sensitive doxorubicin (DOX) polymeric prodrug (P(L-TK-DOX)), and the ROS generation agent (α-tocopheryl succinate, α-TOS); and this delivery system is expected to enhance PSMA (-) prostate cancer therapeutic effect, increase selective accumulation at tumor site and overcome intracellular incomplete drug release. After administration i.v injection, ATD-NPs could specifically accumulate in tumor site and markedly be internalized by cancer cells based on the DUP-1 (a PSMA (-) cancer cells specific target peptide). Subsequently, ATD-NPs could be dissociated under the high concentration reactive oxygen species (ROS) condition, resulting in DOX and α-TOS release. Then, the released α-TOS could be reacted with mitochondria to produce ROS, which in turn accelerating the release of drugs. Finally achieved the purpose of enhancing therapeutic efficacy and reducing side effect. Both in vitro and in vivo experiments demonstrated that the combination of tumor actively-targeted and self-amplifying ROS-responsive drug release showed more significant antitumor activity in the human PSMA (-) prostate cancer.

CONCLUSION

The described technology unifies the tumor actively targets, self-amplified drug release, and excellent biocompatibility into one formulation, are promising for cancer treatment.

Stimuli-responsive nanodrug self-assembled from amphiphilic drug-inhibitor conjugate for overcoming multidrug resistance in cancer treatment

Severe multidrug resistance (MDR) often develops in the process of chemotherapy for most small molecule anticancer drugs, which results in clinical chemotherapy failures.

Methods: Here, a nanodrug is constructed through the self-assembly of amphiphilic drug-inhibitor conjugates (ADIC) containing a redox-responsive linkage for reversing the multidrug resistance (MDR) in cancer treatment. Specifically, hydrophilic anticancer irinotecan (Ir) and hydrophobic P-gp protein inhibitor quinine (Qu) are linked by a redox responsive bridge for overcoming MDR of tumors.

Results: Ir-ss-Qu is able to self-assemble into nanoparticles (NPs) in water and shows the longer blood retention half-life compared with that of free Ir or Qu, which facilitates drug accumulation in tumor site. After endocytosis of Ir-ss-Qu NPs by drug-resistant tumor cells, the disulfide bond in the linkage between Ir and Qu is cleaved rapidly induced by glutathione (GSH) to release anticancer drug Ir and inhibitor Qu synchronously. The released Qu can markedly reduce the expression of P-gp in drug-resistant tumor cells and inhibits P-gp to pump Ir out of the cells. The increased concentration of intracellular Ir can effectively improve the therapeutic efficacy.

Conclusions: Such redox-responsive Ir-ss-Qu NPs, as a drug delivery system, exhibit very high cytotoxicity and the most effective inhibitory to the growth of drug-resistant breast cancer compared with that of free therapeutic agents in vitro and in vivo.

Regulating intracellular ROS signal by a dual pH/reducing-responsive nanogels system promotes tumor cell apoptosis

Purpose: The levels of reactive oxygen species (ROS) in tumor cells are much higher than that in normal cells, and rise rapidly under the influence of exogenous or endogenous inducing factors, eventually leading to the apoptosis of tumor cells. Therefore, this study prepared a dual pH/reducing-responsive poly (N-isopropylacrylamide-co-Cinnamaldehyde-co-D-α-tocopheryl polyethylene glycol 1000 succinate, PssNCT) nanogels, which employed two exogenous ROS inducers, cinnamaldehyde (CA) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), to selectively induce apoptosis by regulating ROS levels in tumor cells. Methods: The PssNCT nanogels were prepared by the free radical precipitation polymerization under the crosslink between pH-sensitive hydrazone and reducing-sensitive disulfide bonds, followed by the physicochemical and morphological characteristics investigations. Plasma stability, dual pH/reducing responsive degradation and in vitro release were also assessed. In cell experiments, cytotoxicity in different cells were first detected. The intracellular ROS levels and mitochondrial functions of tumor cells were then evaluated. Moreover, the apoptosis and western-blot assays were employed to verify the association between ROS levels elevation and apoptosis in tumor cells. Results: The nanogels exhibited a round-like hollow structure with the diameter smaller than 200nm. The nanogels were stable in plasma, while showed rapid degradation in acidic and reducing environments, thus achieving significant release of CA and TPGS in these media. Furthermore, the sufficient amplification of ROS signals was induced by the synergistically function of CA and TPGS on mitochondria, which resulted in the opening of the mitochondrial apoptotic pathway and enhanced cytotoxicity on MCF-7 cells. However, nanogels barely affected L929 cells owing to their lower intracellular ROS basal levels. Conclusion: The specific ROS regulation method achieved by these nanogels could be explored to selectively kill tumor cells according to the difference of ROS signals in different kinds of cells.

Programmable Therapeutic Nanodevices with Circular Amplification of H2 O2 in the Tumor Microenvironment for Synergistic Cancer Therapy

Tumor microenvironment activated nanodevices have remarkable superiority to enhance therapeutic efficacy and minimize side effects, but their practical applications are dramatically reduced by the low abundance and heterogeneous distribution of specific stimuli at the tumor site. Herein, programmable vesicular nanodevices based on the triblock copolymer containing poly(ethylene glycol) (PEG) and poly(caprolactone) (PCL) with peroxalate esters (PO) as hydrogen peroxide-responsive linkage (PEG-PO-PCL-PO-PEG), are developed for co-delivery of hypoxia-activated prodrug (AQ4N) and glucose oxidase (GOD). The obtained nanodevices (PAG) can be activated by the high level of H2 O2 in tumor microenvironment to improve the permeability of membranes for glucose entrance. Afterward, the oxidation of glucose catalyzed by GOD produces amplified H2 O2 amounts which in turn induce complete destruction of PAG for fast release of AQ4N and GOD. Ultimately, the PAG can exert programmable therapeutic effects from the following aspects: 1) starvation therapy by cutting off the energy supply from glucose through GOD catalysis; 2) oxidative cytotoxicity after H2 O2 amplification; 3) chemotherapy of AQ4N activated by the intensified tumor hypoxia microenvironment after oxygen consumption. The stimuli amplification, controlled drug release, synergistic therapy, and corresponding mechanisms of PAG are demonstrated. Therefore, the presented work could provide significant new insights for cancer treatment.

An ROS-responsive and self-accelerating drug release nanoplatform for overcoming multidrug resistance

An 'on-demand' drug release and ROS-responsive nanoparticle was prepared by chemically conjugating hydrophobic α-tocopheryl succinate to hydrophilic poly(ethylene glycol) via a thioketal linker. This nanoparticle encapsulated with doxorubicin and α-tocopheryl succinate exhibited remarkable efficiency in reversing multidrug resistance both in vitro and in vivo.

Design of dual drug-loaded dendrimer/carbon dot nanohybrids for fluorescence imaging and enhanced chemotherapy of cancer cells

Design of powerful nanosystems to overcome multidrug resistance (MDR) for effective chemotherapy of cancer currently remains a great challenge. Herein, we report the development of a poly(amidoamine) (PAMAM) dendrimer/carbon dot nanohybrid for dual drug loading to overcome MDR and simultaneously monitor cancer cells via fluorescence imaging. First, blue-emitting carbon dots (CDs) were synthesized using sodium citrate as a carbon source via the hydrothermal method and used as a carrier to load the anticancer drug doxorubicin (DOX) through non-covalent interactions, thus forming CDs/DOX complexes. In parallel, PAMAM dendrimers of generation 5 (G5) were covalently modified by the targeting ligand cyclic arginine-glycine-aspartic (RGD) peptide and the drug efflux inhibitor d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). Then, through electrostatic interaction, functional dendrimers (G5-RGD-TPGS) were complexed with CDs/DOX complexes to form a dual drug-loaded nanohybrid system. The dual drug-loaded dendrimer/CD nanohybrids were well characterized. We showed that the nanohybrids possessed good colloidal stability and enabled significant inhibition of cancer cells due to the presence of TPGS, which can inhibit P-glycoprotein (P-gp) by decreasing ATP levels and increasing ROS levels; simultaneously, fluorescence imaging of cancer cells could be achieved in vitro due to the luminescence of CDs. In addition, the attached RGD ligands rendered the nanohybrid with targeting specificity to cancer cells expressing αvβ3 integrin receptors. The developed dual drug-loaded dendrimer/CD nanohybrid may be used as a promising theranostic platform to overcome MDR for enhanced chemotherapy as well as for fluorescence imaging of cancer cells.

Logical design and application of prodrug platforms

This review summarizes the current state of prodrugs and elaborates the logical design and future development of the prodrug platform.

Vitamin E d-α-Tocopheryl Polyethylene Glycol Succinate (TPGS) Provokes Cell Death in Human Neuroblastoma SK-N-SH Cells via a Pro-Oxidant Signaling Mechanism

Neuroblastoma (NB) is the most common neoplasm during infancy. Unfortunately, NB is still a lethal cancer. Therefore, innovative curative therapies are immediately required. In this study, we showed the prodeath activity of TPGS in human NB SK-N-SH cancer cells. NB cells were exposed to TPGS (10-80 μM). We report for the first time that TPGS induces cell death by apoptosis in NB cells via a pro-oxidant-mediated signaling pathway. Certainly, H₂O₂ directly oxidizes DJ-1 cysteine¹⁰⁶-thiolate into DJ-1 cysteine¹⁰⁶-sulfonate, indirectly activates the transcription factors NF-kappaB, p53, and c-JUN, induces the upregulation of mitochondria regulator proteins BAX/PUMA, and provokes the loss of mitochondrial membrane potential (ΔΨ_m) and the activation of caspase-3/AIF, leading to nuclear disintegration, demonstrated by cellular and biochemical techniques such as fluorescence microscopy, flow cytometry, and Western blot analysis. Since TPGS is a U.S. Food and Drug Administration (FDA)-approved pharmaceutical excipient, this molecule might be used in clinical trials for NB treatment.