Redox-sensitive mPEG-SS-PTX/TPGS mixed micelles: An efficient drug delivery system for overcoming multidrug resistance

Optimizing Paclitaxel Oral Absorption and Bioavailability: TPGS Co-Coating via Supercritical Anti-Solvent Fluidized Bed Technology

Supercritical anti-solvent fluidized bed (SAS-FB) coating technology has the advantages of reducing particle size, preventing high surface energy particle aggregation, improving the dissolution performance and bioavailability of insoluble drugs. The poor solubility of Biopharmaceutics Classification System (BCS) class IV drugs poses challenges in achieving optimal bioavailability. Numerous anti-cancer drugs including paclitaxel (PTX) belong to the BCS class IV, hindering their therapeutic efficacy. To address this concern, our study explored SAS-FB technology to coat PTX with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) onto lactose. Under our optimized conditions, we achieved a PTX coating efficiency of 96.8%. Further characterization confirmed the crystalline state of PTX in the lactose surface coating by scanning electron microscopy and X-ray powder diffraction. Dissolution studies indicated that SAS-FB processed samples release over 95% of the drug within 1 min. Moreover, cell transmembrane transport assays demonstrated that SAS-FB processed PTX samples co-coated with TPGS had an enhanced PTX internalization into cells and a higher permeability coefficient compared to those without TPGS. Finally, compared to unprocessed PTX, SAS-FB (TPGS) and SAS-FB processed samples showed a 2.66- and 1.49-fold increase in oral bioavailability in vivo, respectively. Our study highlights the efficacy of SAS-FB co-coating for PTX and TPGS as a promising strategy to overcome bioavailability challenges inherent in BCS class IV drugs. Our approach holds broader implications for enhancing the performance of similarly classified medications.

Site-specific delivery of cisplatin and paclitaxel mediated by liposomes: A promising approach in cancer chemotherapy

The site-specific delivery of drugs, especially anti-cancer drugs has been an interesting field for researchers and the reason is low accumulation of cytotoxic drugs in cancer cells. Although combination cancer therapy has been beneficial in providing cancer drug sensitivity, targeted delivery of drugs appears to be more efficient. One of the safe, biocompatible and efficient nano-scale delivery systems in anti-cancer drug delivery is liposomes. Their particle size is small and they have other properties such as adjustable physico-chemical properties, ease of functionalization and high entrapment efficiency. Cisplatin is a chemotherapy drug with clinical approval in patients, but its accumulation in cancer cells is low due to lack of targeted delivery and repeated administration results in resistance development. Gene and drug co-administration along with cisplatin/paclitaxel have resulted in increased sensitivity in tumor cells, but there is still space for more progress in cancer therapy. The delivery of cisplatin/paclitaxel by liposomes increases accumulation of drug in tumor cells and impairs activity of efflux pumps in promoting cytotoxicity. Moreover, phototherapy along with cisplatin/paclitaxel delivery can increase potential in tumor suppression. Smart nanoparticles including pH-sensitive nanoparticles provide site-specific delivery of cisplatin/paclitaxel. The functionalization of liposomes can be performed by ligands to increase targetability towards tumor cells in mediating site-specific delivery of cisplatin/paclitaxel. Finally, liposomes can mediate co-delivery of cisplatin/paclitaxel with drugs or genes in potentiating tumor suppression. Since drug resistance has caused therapy failure in cancer patients, and cisplatin/paclitaxel are among popular chemotherapy drugs, delivery of these drugs mediates targeted suppression of cancers and prevents development of drug resistance. Because of biocompatibility and safety of liposomes, they are currently used in clinical trials for treatment of cancer patients. In future, the optimal dose of using liposomes and optimal concentration of loading cisplatin/paclitaxel on liposomal nanocarriers in clinical trials should be determined.

Innovative Design of Targeted Nanoparticles: Polymer-Drug Conjugates for Enhanced Cancer Therapy

Polymer-drug conjugates (PDCs) have shown great promise in enhancing the efficacy and safety of cancer therapy. These conjugates combine the advantageous properties of both polymers and drugs, leading to improved pharmacokinetics, controlled drug release, and targeted delivery to tumor tissues. This review provides a comprehensive overview of recent developments in PDCs for cancer therapy. First, various types of polymers used in these conjugates are discussed, including synthetic polymers, such as poly(↋-caprolactone) (PCL), D-α-tocopheryl polyethylene glycol (TPGS), and polyethylene glycol (PEG), as well as natural polymers such as hyaluronic acid (HA). The choice of polymer is crucial to achieving desired properties, such as stability, biocompatibility, and controlled drug release. Subsequently, the strategies for conjugating drugs to polymers are explored, including covalent bonding, which enables a stable linkage between the polymer and the drug, ensuring controlled release and minimizing premature drug release. The use of polymers can extend the circulation time of the drug, facilitating enhanced accumulation within tumor tissues through the enhanced permeability and retention (EPR) effect. This, in turn, results in improved drug efficacy and reduced systemic toxicity. Moreover, the importance of tumor-targeting ligands in PDCs is highlighted. Various ligands, such as antibodies, peptides, aptamers, folic acid, herceptin, and HA, can be incorporated into conjugates to selectively deliver the drug to tumor cells, reducing off-target effects and improving therapeutic outcomes. In conclusion, PDCs have emerged as a versatile and effective approach to cancer therapy. Their ability to combine the advantages of polymers and drugs offers enhanced drug delivery, controlled release, and targeted treatment, thereby improving the overall efficacy and safety of cancer therapies. Further research and development in this field has great potential to advance personalized cancer treatment options.

Smart redox-sensitive micelles based on chitosan for dasatinib delivery in suppressing inflammatory diseases

Dasatinib (DAS) exhibits anti-inflammatory effects by retrieving the balance between inflammatory and anti-inflammatory cytokines secreted by macrophages. The aim of this study was the development of redox-responsive micelles with the potential of passive targeting and on-demand drug release for DAS delivery to macrophages. For this purpose, two molecular weights of chitosan (CHIT) were conjugated to DAS at different molar ratios using 3,3'-dithiodipropionic anhydride (DTDPA) as disulfide bond containing linker to synthesize a series of CHIT-S-S-DAS amphiphilic conjugates. Micelles obtained by the sonication method had particle sizes of 129.3-172.2 nm, zeta potentials of +17.5 to +20.9 mV, drug contents of 0.90-7.20 %, CMC values of 35.3-96.6 μg/ml, and exhibited redox-responsive in vitro drug release. Optimized micelles were non-toxic and dramatically more efficient than non-redox responsive micelles in reducing TNF-α and IL-6 and increasing IL-10 secretion from LPS-stimulated RAW264.7 cells. Furthermore, the redox-responsive micelles were able to reduce the mice paw edema, reduce the plasma levels of pro-inflammatory cytokines and increase plasma level of IL-10, considerably more than free DAS and non-redox responsive micelles in carrageenan-induced mice paw edema model of inflammation.

Engineering Transferrin-Decorated Pullulan-Based Prodrug Nanoparticles for Redox Responsive Paclitaxel Delivery to Metastatic Lung Cancer Cells

Paclitaxel (PTX) remains a cornerstone in the treatment of locally advanced and metastatic lung cancer. To improve its therapeutic indices against lung cancer, novel redox-sensitive pullulan/PTX-based prodrug NPs (PULL-SS-PTX NPs) were accomplished, which were further surface-decorated with transferrin (TF), a cancer cell-targeting ligand, to afford TF-PULL-SS-PTX NPs. These prodrug NPs (drug content, >37% and average size, 134-163 nm) rapidly dismantled their self-assembled architecture upon exposure to simulated reducing conditions, causing a triggered drug release as compared to the control scaffold (PULL-CC-PTX NPs). These scaffolds also evidenced outstanding colloidal stability, cellular uptake efficiency, and discriminating cytotoxicity between the cancer and healthy cells. Intravenously delivered redox-sensitive NPs exhibited improved tumor-suppressing properties as compared to the control nanovesicles (PULL-CC-PTX NPs) in a B16-F10 melanoma lung metastasis mice model. The targeting efficiency and associated augmented anticancer potentials of TF-PULL-SS-PTX NPs relative to TF-free redox-responsive NPs and Taxol intravenous injection were also established on the transferrin receptor (TFR) overexpressed Lewis lung carcinoma (LLC-luc) cell-bearing mice model. Moreover, the TF-functionalized scaffold displayed a reduced systemic toxicity compared to that of Taxol intravenous injection. Overall, the proposed TF-decorated prodrug NPs could be a promising nanomedicine for intracellular PTX delivery against metastatic lung cancer.

Combination of polythyleneimine regulating autophagy prodrug and Mdr1 siRNA for tumor multidrug resistance

Multidrug resistance (MDR) has been restricting the efficacy of chemotherapy, which mainly include pump resistance and non-pump resistance. In order to fight overall MDR, a novel targeted gene/drug co-deliver nano system is developed, which can suppress the drug efflux pumps and modulate autophagy to overcoming both pump and non-pump resistance. Here, small interfere RNA (siRNA) is incorporated into polymer-drug conjugates (PEI-PTX, PP) which are composed of polyethyleneimine (PEI) and paclitaxel (PTX) via covalent bonds, and hyaluronic acid (HA) is coated on the surface of PP/siRNA to achieve long blood cycle and CD44-targeted delivery. The RNA interference to mdr1 gene is combined with autophagy inhibition by PP, which efficiently facilitate apoptosis of Taxol-resistant lung cancer cells (A549/T). Further study indicates that PEI in PP may play a significant role to block the autophagosome–lysosome fusion process by means of alkalizing lysosomes. Both in vitro and in vivo studies confirm that the nanoassemblies can successfully deliver PTX and siRNA into tumor cells and significantly inhibited A549/T tumor growth. In summary, the polymeric nanoassemblies provide a potential strategy for combating both pump and non-pump resistance via the synergism of RNAi and autophagy modulation.

AIE-Featured Redox-Sensitive Micelles for Bioimaging and Efficient Anticancer Drug Delivery

In the present study, an amphiphilic polymer was prepared by conjugating methoxy poly(ethylene glycol) (mPEG) with tetraphenylethene (TPE) via disulfide bonds (Bi(mPEG-S-S)-TPE). The polymer could self-assemble into micelles and solubilize hydrophobic anticancer drugs such as paclitaxel (PTX) in the core. Combining the effect of TPE, mPEG, and disulfide bonds, the Bi(mPEG-S-S)-TPE micelles exhibited excellent AIE feature, reduced protein adsorption, and redox-sensitive drug release behavior. An in vitro intracellular uptake study demonstrated the great imaging ability and efficient internalization of Bi(mPEG-S-S)-TPE micelles. The excellent anticancer effect and low systemic toxicity were further evidenced by the in vivo anticancer experiment. The Bi(mPEG-S-S)-TPE micelles were promising drug carriers for chemotherapy and bioimaging.

Enhanced photo-hypoxia-activated combination therapy traced by AIE photosensitizer and targeted by hyaluronic acid: Disulphide bond interference of detoxification barrier

The treatment efficacy of anticancer drugs in complex physiological environments is still restricted by multi-drug resistance. To overcome this issue, a nanodrug system of HA-SS@CuS@ZIF-8@TPZ&TBMACN (HSCZTT) that breaks through the detoxification barrier for tirapazamine (TPZ) delivery was developed in this manuscript. In addition to the photothermal effect aroused by CuS in HSCZTT, which can damage tumour cells, TBMACN with photostable fluorescence in the aggregate state can also generate sufficient reactive oxygen species (ROS) to destroy tumour cells. The continuous consumption of oxygen in PDT aggravates the hypoxic environment of tumours, which further activates the TPZ released in the acidic microenvironment of the tumour to achieve apoptosis of the tumour cells. The HSCZTT can not only target the CD44 receptor overexpressed on the surface of the cancer cell, but can also effectively consume a large amount of glutathione (GSH) through the disulphide bond-modified hyaluronic acid, which serves as a targeted disulphide bond, interfering with the detoxification barrier. Our finding presents a rational strategy to overcome multidrug resistance for the improved efficacy of anticancer drugs by the targeting of Hyaluronic acid (HA), release of the drug by the acid response of ZIF-8, breakthrough of the detoxification barrier, precise positioning of the drug release and combined treatment with phototherapy and hypoxia-activated chemotherapy.

Lipid- and TPGS-Based Core-Shell-Type Nanocapsules Endowed with High Paclitaxel Loading and Enhanced Anticancer Potential

The current study elucidates the improved drug loading of paclitaxel (PTX) in lipid- and D-α-tocopheryl polyethylene glycol succinate (TPGS)-based core-shell-type lipid nanocapsules (PTX-TPGS-LNC) for augmenting the therapeutic efficacy and curbing the toxicity. PTX-TPGS-LNCs were formulated by employing anti-solvent precipitation technique and displayed a particle size of 162.1 ± 4.70 nm and % practical drug loading of 15.04 ± 2.44%. Electron microscopy revealed that PTX-TPGS-LNCs have spherical morphology and the inner core was surrounded by a relatively lighter region, i.e., layer of lipids and TPGS. The nature of loaded PTX inside the PTX-TPGS-LNC was also confirmed using DSC and PXRD analysis. The in vitro release study showed biphasic and sustained release pattern of PTX from PTX-TPGS-LNC and it showed ~ threefold higher PTX uptake in MCF-7 cell line in comparison to free PTX. Moreover, it was apparent from the cytotoxicity assay that PTX-TPGS-LNC displayed higher cytotoxicity in MCF-7 cells and revealed ~ 2.92-fold decrease in IC₅₀ value as against free PTX when incubated for 72 h. The apoptotic index in case of PTX-TPGS-LNC was ~ twofold higher than free PTX. The pharmacokinetic profile of PTX-TPGS-LNC revealed a ~ 3.18-fold increase in t_1/2 and a ~ 2.62-fold higher AUC_(0→∞) compared to Intaxel^®. Finally, treatment with PTX-TPGS-LNC demonstrated significant lowering in the % tumor burden and serum toxicity markers compared to marketed formulation Intaxel^®. Thus, the lipid- and TPGS-based core-shell-type LNC with high PTX loading can advance the existing standards of therapy for overshadowing cancer.

Recent Advance in Tumor Microenvironment-Based Stimuli-Responsive Nanoscale Drug Delivery and Imaging Platform

The tumor microenvironment (TME) plays an important role in the development, progression, and metastasis of cancer, and the extremely crucial feature is hypoxic and acidic. Cancer-associated fibroblasts (CAFs), extracellular matrix (ECM), mesenchymal cells, blood vessels, and interstitial fluid are widely recognized as fundamentally crucial hallmarks for TME. As nanotechnology briskly boomed, the nanoscale drug delivery and imaging platform (NDDIP) emerged and has attracted intensive attention. Based on main characteristics of TME, NDDIP can be classified into pH-sensitive delivery and imaging platforms, enzyme-sensitive delivery and imaging platforms, thermo-sensitive delivery and imaging platforms, redox-sensitive delivery and imaging platforms, and light-sensitive delivery and imaging platforms. Furthermore, imageology is one of the significant procedures for disease detection, image-guided drug delivery, and efficacy assessment, including magnetic resonance imaging (MRI), computed tomography (CT), ultrasound (US), and fluorescence imaging. Therefore, the stimuli-responsive NDDIP will be a versatile and practicable tumor disease diagnostic procedure and efficacy evaluation tool. In this review article, we mainly introduce the characteristics of TME and summarize the progress of multitudinous NDDIP as well as their applications.

Research progress of microneedles in the treatment of melanoma

Melanoma is an aggressive malignancy deriving from melanocytes, which is characterized by high tendency of metastases and mortality rate. Current therapies for melanoma, like chemotherapy, immunotherapy and targeted therapy, have the problem of systemic exposure of drugs, which will lead to many side effects and premature degradation of drugs. The resulting low drug accumulation at the lesion limits the therapeutic effect on melanoma and makes the cure rate low. As an emerging drug delivery system, microneedles (MNs) can efficiently deliver drugs through the skin, increase the drug distribution in deeper tumor sites and minimize the leakage of therapeutic drugs into adjacent tissues, thus improving the therapeutic effect. In addition, compared with traditional drug delivery methods, MN-based drug delivery system has the advantages of simplicity, safety and little pain. So MNs can be developed for the treatment of melanoma, which can relieve the pain of patients and improve the survival rate. This review aims to introduce an update on the progress of MNs as an innovative strategy for melanoma, especially when MNs combining with different therapies against melanoma, such as chemotherapy, targeted therapy, immunotherapy, photothermal therapy (PTT), photodynamic therapy (PDT) and synergic therapy.

mPEG-Cholic acid/TPGS mixed micelles for combined delivery of paclitaxel and bufalin to treat hepatocellular carcinoma

In this study, amphiphilic block copolymer mPEG-cholic acid was synthesized in conjunction with TPGS as stabilizer to prepare multifunctional micelles. The formed polymeric micelles (PCTm) were used for the delivery of paclitaxel (PTX) and bufalin (BF). PEG group could enhance solubility and extend circulation time, while cholic acid groups achieved the liver targeted function. Combinations of these approaches could realize a synergistic therapeutic effect in the treatment of advanced hepatocellular carcinoma. CLSM in vitro results demonstrated that drug capsulation into PCTm could enhance cellular uptake. FCM results confirmed the uptake amount of C₆/PCTm was 7.5-fold higher than that of free C₆ after incubation for 2 h. Competitive inhibition test proved the Na⁺-taurocholate co-transporting polypeptide (NTCP) involved in the uptake mechanism of PCTm. Meanwhile, in vivo imaging assays demonstrated that the fluorescence intensity of Cy5.5/PCTm was higher than that of free Cy5.5 on liver and tumor with extended circulation time to 48 h. In addition, in vivo studies confirmed that the combined therapy exhibited the strongest tumor inhibition rate of 82.29% with lower systemic toxicity. Hence, these results indicated that PCTm could provide a promising strategy for targeting hepatocellular carcinoma and achieve the goal of the synergism and attenuation.

Pulmonary Delivery of Reactive Oxygen Species/Glutathione-Responsive Paclitaxel Dimeric Nanoparticles Improved Therapeutic Indices against Metastatic Lung Cancer

Chemotherapeutics often failed to elicit optimal antitumor responses against lung cancer due to their limited exposure and accumulation in tumors. To achieve an effective therapeutic outcome of paclitaxel (PTX) against metastatic lung cancer with attenuated systemic and local toxicities, pulmonary delivery of redox-responsive PTX dimeric nanoparticles (NPs) was introduced. PTX dimers conjugated through variable lengths of diacid linkers containing disulfide bonds (-SS-) (i.e., α-PTX-SS-PTX, β-PTX-SS-PTX, and γ-PTX-SS-PTX) were initially synthesized and were subsequently self-assembled into uniform nanosized particles in the presence of vitamin E TPGS with high drug loading capacity (DE > 97%). Among various redox-sensitive scaffolds, β-PTX-SS-PTX NPs exhibited an optimal reactive oxygen species/glutathione-responsive drug release behavior, causing a lower local toxicity profile of PTX in the lungs. The scaffolds also demonstrated excellent colloidal stability, cellular uptake efficiency, and discriminating cytotoxicity between cancer and healthy cells. Further, they depicted an improved lung retention as compared to the control nanovesicles (β-PTX-CC-PTX) devoid of the redox-sensitive disulfide motif. In the B16F10 melanoma metastatic lung cancer mouse model, intratracheally delivered β-PTX-SS-PTX NPs exhibited a stronger anticancer potential with reduced systemic toxicity as compared to Taxol intravenous injection containing an equivalent PTX dose. The PTX dimeric NPs could also dramatically reduce the local toxicity relative to Taxol following their pulmonary delivery. Thus, this study presents redox-responsive PTX dimeric NPs as a promising nanomedicine for improved therapeutic efficacy against metastatic lung cancer.

The reversal of chemotherapy-induced multidrug resistance by nanomedicine for cancer therapy

Multidrug resistance (MDR) of cancer is a persistent problem in chemotherapy. Scientists have considered the overexpressed efflux transporters responsible for MDR and chemotherapy failure. MDR extremely limits the therapeutic effect of chemotherapy in cancer treatment. Many strategies have been applied to solve this problem. Multifunctional nanoparticles may be one of the most promising approaches to reverse MDR of tumor. These nanoparticles can keep stability in the blood circulation and selectively accumulated in the tumor microenvironment (TME) either by passive or active targeting. The stimuli-sensitive or organelle-targeting nanoparticles can release the drug at the targeted-site without exposure to normal tissues. In order to better understand reversal of MDR, three main strategies are concluded in this review. First strategy is the synergistic effect of chemotherapeutic drugs and ABC transporter inhibitors. Through directly inhibiting overexpressed ABC transporters, chemotherapeutic drugs can enter into resistant cells without being efflux. Second strategy is based on nanoparticles circumventing over-expressed efflux transporters and directly targeting resistance-related organelles. Third approach is the combination of multiple therapy modes overcoming cancer resistance. At last, numerous researches demonstrated cancer stem-like cells (CSCs) had a deep relation with drug resistance. Here, we discuss two different drug delivery approaches of nanomedicine based on CSC therapy.

Novel redox-sensitive thiolated TPGS based nanoparticles for EGFR targeted lung cancer therapy

Novel glutathione (GSH) redox-sensitive thiolated vitaminE-PEG1000-succinate (TPGH-SH) was synthesized by conjugating TPGS with 4-amino thiophenol (4-ATP) and confirmed by FTIR and NMR studies. Following, docetaxel (DTX) loaded, cetuximab (CTB) conjugated redox sensitive TPGS-SH nanoparticles (TPGS-SH NP) were prepared by dialysis method and screened for size, charge, DTX entrapment, which revealed that size, surface charge and percent entrapment are in the range of 183-227 nm, +18 to +26 mV and 68-71%. SEM, TEM, AFM have reflected the spherical and uniform size of NP with a smooth surface. In-vitro release studies were performed in media containing different concentrations of GSH to study their effect on drug release and drug release of up to 94.5%, at pH 5.5, GSH 20 mM, is observed within 24 h. The pH/redox sensitivity studies revealed the better stability of NP at higher pH and lower GSH concentrations. In-vitro cytotoxicity, cellular uptake, migration and apoptotic assays, performed on A549 cells, have proved that targeted formulation produced higher cytotoxicity (significantly less IC50 value) and uptake and also prevented cell migration. Pharmacokinetic and histopathological screening were performed on CF rats, which demonstrated promising results. The in-vivo efficacy studies on benzo(a)pyrene induced mice lung cancer model showed that targeted TPGS-SH NP has significantly reduced the cell number than the model control.

Octreotide-Targeted Lcn2 siRNA PEGylated Liposomes as a Treatment for Metastatic Breast Cancer

Lcn2 overexpression in metastatic breast cancer (MBC) can lead to cancer progression by inducing the epithelial-to-mesenchymal transition and enhancing tumor angiogenesis. In this study, we engineered a PEGylated liposomal system encapsulating lipocalin 2 (Lcn2) small interfering RNA (Lcn2 siRNA) for selective targeting MBC cell line MCF-7 and triple-negative breast cancer cell line MDA-MB-231. The PEGylated liposomes were decorated with octreotide (OCT) peptide. OCT is an octapeptide analog of somatostatin growth hormone, having affinity for somatostatin receptors, overexpressed on breast cancer cells. Optimized OCT-targeted Lcn2 siRNA encapsulated PEGylated liposomes (OCT-Lcn2-Lipo) had a mean size of 152.00 nm, PDI, 0.13, zeta potential 4.10 mV and entrapment and loading efficiencies of 69.5% and 7.8%, respectively. In vitro uptake and intracellular distribution of OCT-Lcn2-Lipo in MCF-7 and MDA-MB-231 and MCF-12A cells demonstrated higher uptake for the OCT-targeted liposomes at 6 h by flow cytometry and confocal microscopy. OCT-Lcn2-lipo could achieve approximately 55-60% silencing of Lcn2 mRNA in MCF-7 and MDA-MB-231 cells. OCT-Lcn2-Lipo also demonstrated in vitro anti-angiogenic effects in MCF-7 and MDA-MB-231 cells by reducing VEGF-A and reducing the endothelial cells (HUVEC) migration levels. This approach may be useful in inhibiting angiogenesis in MBC.

pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages for enhanced MDR reversal and chemotherapy

TPGS approved by FDA can be used as a P-gp inhibitor to effectively reverse multi-drug resistance (MDR) and as an anticancer agent for synergistic antitumor effects. However, the comparatively high critical micelle concentration (CMC), low drug loading (DL) and poor tumor target limit its further clinical application. To overcome these drawbacks, the pH-sensitive star-shaped TPGS copolymers were successfully constructed via using pentaerythritol as the initial materials, ortho esters as the pH-triggered linkages and TPGS active-ester as the terminated MDR material. The amphiphilic star-shaped TPGS copolymers could self-assemble into free and doxorubicin (DOX)-loaded micelles at neutral aqueous solutions. The micelles exhibited the lower CMC (8.2 × 10⁻⁵ mg/ml), higher DL (10.8%) and long-term storage and circulation stability, and showed enhanced cellular uptake, apoptosis, cytotoxicity, and growth inhibition for in vitro MCF-7/ADR and/or MCF-7/ADR multicellular spheroids and in vivo MCF-7/ADR tumors via efficiently targeted drug release at tumoral intracellular pH (5.0), MDR reversal of TPGS, and synergistic effect of DOX and TPGS. Therefore, the pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages are potentially useful to clinically transform for enhanced MDR cancer treatment.

l-Carnitine conjugated chitosan-stearic acid polymeric micelles for improving the oral bioavailability of paclitaxel

A delivery system based on l-carnitine (LC) conjugated chitosan (CS)-stearic acid polymeric micelles has been developed for improving the oral bioavailability of paclitaxel (PTX) through targeting intestinal organic cation/carnitine transporter 2 (OCTN2). Stearic acid grafted chitosan (CS-SA), as micelle skeleton material, was synthesized by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling reaction. The PTX-loaded micelles were prepared by solvent evaporation-hydration method, and the ligand LC was conjugated onto the micelle surface by anchoring its derivative stearoyl group to the lipophilic core of micelle. The modified polymeric micelles showed regular spherical shapes with small particle size of 157.1 ± 5.2 nm and high drug loading capacity of 15.96 ± 0.20 wt%, and the micelle stability in water was supported by low critical micelle concentration of 14.31 ± 0.21 μg/ml. The drug-loaded micelles presented a slow and incomplete in vitro release, and the pharmacokinetic studies indicated the micelle carriers increased the relative bioavailability of PTX to 165.8% against the commercial formulation. The enhancement effect on intestinal absorption was also confirmed by the intracellular uptake of Caco-2 cells. The proposed micelle carrier system manifested a prospective tool for oral drug delivery.

Stimuli-Responsive Micelles with Detachable Poly(2-ethyl-2-oxazoline) Shell Based on Amphiphilic Polyurethane for Improved Intracellular Delivery of Doxorubicin

Polyurethanes (PUs) have various biomedical applications including controlled drug delivery. However, the incompletely release of drug at tumor sites limits the efficiency of these drug loaded polyurethane micelles. Here we report a novel polymer poly(2-ethyl-2-oxazoline)-SS-polyurethane-SS-poly(2-ethyl-2-oxazoline) triblock polyurethane (PEtOz-PU(PTMCSS)-PEtOz). The hydrophilic pH-responsive poly(2-ethyl-2-oxazoline) was used as an end-block to introduce pH responsiveness, and the hydrophobic PU middle-block was easily synthesized by the reaction of poly (trimethylene carbonate) diol containing disulfide bonds (PTMC-SS-PTMC diol) and bis (2-isocyanatoethyl) disulfide (CDI). PEtOz-PU(PTMCSS)-PEtOz could self-assemble to form micelles (176 nm). The drug release profile of PEtOz-PU(PTMCSS)-PEtOz micelles loaded with Doxorubicin (DOX) was studied in the presence of acetate buffer (10 mM, pH 5.0) and 10 mM dithiothreitol (DTT). The results showed that under this environment, DOX-loaded polyurethane micelles could release DOX faster and more thoroughly, about 97% of the DOX was released from the DOX-loaded PEtOz-PU(PTMCSS)-PEtOz micelle. In addition, fluorescent microscopy and cell viability assays validated that the DOX-loaded polyurethane micelle strongly inhibits the growth of C6 cells, suggesting their potential as a new nanomedicine against cancer.

Formulation, Pharmacokinetic Evaluation and Cytotoxicity of an Enhanced- penetration Paclitaxel Nanosuspension

BACKGROUND

Improving poorly soluble drugs into druggability was a major problem faced by pharmaceutists. Nanosuspension can improve the druggability of insoluble drugs by improving the solubility, chemical stability and reducing the use of additives, which provided a new approach for the development and application of the insoluble drugs formulation. Paclitaxel (PTX) is a well-known BCS class IV drug with poor solubility and permeability. Also, many studies have proved that paclitaxel is a substrate of the membrane-bound drug efflux pump P-glycoprotein (P-gp), therefore it often shows limited efficacy against the resistant tumors and oral absorption or uptake.

OBJECTIVE

To manufacture an enhanced-penetration PTX nanosuspension (PTX-Nanos), and evaluate the physicochemical property, pharmacokinetics and tissue distribution in vivo and cytotoxic effect in vitro.

METHODS

PTX-Nanos were prepared by microprecipitation-high pressure homogenization, with a good biocompatibility amphiphilic block copolymer poly(L-phenylalanine)-b-poly(L-aspartic acid) (PPA-PAA) as stabilizer.

RESULTS

The PTX-Nanos had a sustained-dissolution manner and could effectively reduce plasma peak concentration and extend plasma circulating time as compared to PTX injection, markedly passively targeting the MPS-related organs, such as liver and spleen. This unique property might enhance treatment of cancer in these tissues and reduce the side effects in other normal tissues. Moreover, the hybrid stabilizers could enhance penetration of PTX in PTX-Nanos to multidrug resistance cells.

CONCLUSION

To sum up, our results showed that the optimal formula could improve the solubility of PTX and the stability of the product. The PTX-Nanos developed in this research would be a promising delivery platform in cancer treatment.

Nano Encapsulated Curcumin: And Its Potential for Biomedical Applications

Curcumin, a yellow-colored polyphenol extracted from the rhizome of turmeric root, is commonly used as a spice and nutritional supplement. It exhibits many pharmacological activities such as anti-inflammatory, anti-bacterial, anti-cancer, anti-Alzheimer, and anti-fungal. However, the therapeutic application of curcumin is limited by its extremely low solubility in aqueous buffer, instability in body fluids, and rapid metabolism. Nano delivery system has shown excellent potential to improve the solubility, biocompatibility and therapeutic effect of curcumin. In this review, we focus on the recent development of nano encapsulated curcumin and its potential for biomedical applications.

An Overview of the Antioxidant Effects of Ascorbic Acid and Alpha Lipoic Acid (in Liposomal Forms) as Adjuvant in Cancer Treatment

Antioxidants are known to minimize oxidative stress by interacting with free radicals produced as a result of cell aerobic reactions. Oxidative stress has long been linked to many diseases, especially tumours. Therefore, antioxidants play a crucial role in the prevention or management of free radical-related diseases. However, most of these antioxidants have anticancer effects only if taken in large doses. Others show inadequate bioavailability due to their instability in the blood or having a hydrophilic nature that limits their permeation through the cell membrane. Therefore, entrapping antioxidants in liposomes may overcome these drawbacks as liposomes have the capability to accommodate both hydrophilic and hydrophobic compounds with a considerable stability. Additionally, liposomes have the capability to accumulate at the cancer tissue passively, due to their small sizes, with enhanced drug delivery. Additionally, liposomes can be engineered with targeting moieties to increase the delivery of chemotherapeutic agents to specific tumour cells with decreased accumulation in healthy tissues. Therefore, combined use of liposomes and antioxidants, with or without chemotherapeutic agents, is an attractive strategy to combat varies tumours. This mini review focuses on the liposomal delivery of selected antioxidants, namely ascorbic acid (AA) and alpha-lipoic acid (ALA). The contribution of these nanocarriers in enhancing the antioxidant effect of AA and ALA and consequently their anticancer potentials will be demonstrated.

Nanotechnology approaches in the current therapy of skin cancer

Skin cancer is a high burden disease with a high impact on global health. Conventional therapies have several drawbacks; thus, the development of effective therapies is required. In this context, nanotechnology approaches are an attractive strategy for cancer therapy because they enable the efficient delivery of drugs and other bioactive molecules to target tissues with low toxic effects. In this review, nanotechnological tools for skin cancer will be summarized and discussed. First, pathology and conventional therapies will be presented, followed by the challenges of skin cancer therapy. Then, the main features of developing efficient nanosystems will be discussed, and next, the most commonly used nanoparticles (NPs) described in the literature for skin cancer therapy will be presented. Subsequently, the use of NPs to deliver chemotherapeutics, immune and vaccine molecules and nucleic acids will be reviewed and discussed as will the combination of physical methods and NPs. Finally, multifunctional delivery systems to codeliver anticancer therapeutic agents containing or not surface functionalization will be summarized.

Enzyme-responsive polymeric micelles with fluorescence fabricated through aggregation-induced copolymer self-assembly for anticancer drug delivery

The TPE moiety with AIE is employed as functional hydrophobic chain to induce copolymer self-assembly and form polymeric micelle that can show enzyme-responsive drug delivery.

Improved Antitumor Activity of Novel Redox-Responsive Paclitaxel-Encapsulated Liposomes Based on Disulfide Phosphatidylcholine

The microtubule inhibitor paclitaxel (PTX) is used to treat a wide range of solid tumors. Due to the poor aqueous solubility of PTX, a continuous demand for safe, efficient PTX formulations with improved antitumor activity exists. Here, we report a novel form of redox-sensitive paclitaxel (PTX)-encapsulated liposomes based on the previously developed disulfide phosphatidylcholine (SS-PC). PTX-loaded stealth liposomes (PTX/SS-LP) composed of SS-PC, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-PEG₂₀₀₀ (DSPE-PEG₂₀₀₀), and cholesterol were prepared using the reverse-phase evaporation method. The characterization of the PTX/SS-LP liposomes using dynamic light scattering and transmission electron microscopy confirmed their uniform particle size and typical unilamellar vesicle structure with an average bilayer thickness of approximately 4 nm. Changes in the size and morphology as well as the rapid release of PTX triggered by the addition of dithiothreitol revealed the redox sensitivity of PTX/SS-LP. Finally, evaluations in MCF-7 and A549 cells in vitro and in BALB/c mice in vivo revealed the improved anticancer efficiency, biodistribution, and safety of PTX/SS-LP compared with those of Taxol and nonredox-sensitive PTX/LP. In conclusion, PTX/SS-LP displays a redox-responsive release of paclitaxel with improved antitumor activity and has great potential as a next-generation stealth liposomal PTX delivery system.

Redox-Responsive Disulfide Bond-Bridged mPEG-PBLA Prodrug Micelles for Enhanced Paclitaxel Biosafety and Antitumor Efficacy

The toxicity and side effects of traditional chemotherapeutic drugs are the main causes of chemotherapy failure. To improve the specificity and selectivity of chemotherapeutic drugs for tumor cells, a novel redox-sensitive polymer prodrug, polyethylene glycol-poly (β-benzyl-L-aspartate) (PEG-PBLA)-SS-paclitaxel (PPSP), was designed and synthesized in this study. The PPSP micelle was manufactured via high-speed dispersion stirring and dialysis. The particle size and zeta potential of this prodrug micelle were 63.77 ± 0.91 nm and −25.8 ± 3.24 mV, respectively. The micelles were uniformly distributed and presented a spherical morphology under a transmission electron microscope. In the tumor physiological environment, the particle size of the PPSP micelles and the release rate of paclitaxel (PTX) were significantly increased compared with those of mPEG-PBLA-CC-PTX (PPCP) micelles, reflecting the excellent redox-sensitive activity of the PPSP micelles. The inhibitory effect of PPSP on HepG2, MCF-7 and HL-7702 cell proliferation was investigated with MTT assays, and the results demonstrated that PPSP is superior to PTX with respect to the inhibition of two tumor cell types at different experimental concentration. Simultaneously PPSP has lower toxicity against HL-7702 cells then PTX and PPCP. Moreover, the blank micelle from mPEG-PBLA showed no obvious toxicity to the two tumor cells at different experimental concentrations. In summary, the redox-sensitive PPSP micelle significantly improved the biosafety and the anti-tumor activity of PTX.

AIE Supramolecular Assembly with FRET Effect for Visualizing Drug Delivery

Here, we constructed a nanostructured pH/redox dual-responsive supramolecular drug carrier with both aggregation-induced emission (AIE) and Forster resonance energy transfer (FRET) effects, which enabled selective drug release and monitoring drug delivery and release processes. Taking the hyperbranched polyamide amine (H-PAMAM) with intrinsic AIE effects as the core, poly(ethylene glycol) (PEG) was bridged on its periphery by dithiodipropionic acid. Then, through the host-guest interaction of PEG and α-cyclodextrin, the supramolecular nanoparticles with AIE effects were constructed to load the anticancer drug doxorubicin (DOX). The supramolecular assembly has sufficiently large DOX loading due to the abundant cavities formed by branched structures. The hyperbranched core H-PAMAM has strong fluorescence, and the dynamic track of drug carriers and the dynamic drug release process can be monitored by the AIE and FRET effects between H-PAMAM and DOX, respectively. Furthermore, the introduction of disulfide bonds and the pH sensitivity of H-PAMAM enable the achievement of rapid selective release of loaded DOX at the tumor while remaining stable under normal physiological conditions. In vitro cytotoxicity indicates that the drug-loaded supramolecular assembly has a good therapeutic effect on cancer. In addition, the H-PAMAM core is different from the traditional AIE functional group, which has no conjugated structure, such as a benzene ring, thereby providing better biocompatibility. This technology will have broad applications as a new drug delivery system.

Models used to screen for the treatment of multidrug resistant cancer facilitated by transporter-based efflux

PURPOSE

Efflux transporters of the adenosine triphosphate-binding cassette (ABC)-superfamily play an important role in the development of multidrug resistance (multidrug resistant; MDR) in cancer. The overexpression of these transporters can directly contribute to the failure of chemotherapeutic drugs. Several in vitro and in vivo models exist to screen for the efficacy of chemotherapeutic drugs against MDR cancer, specifically facilitated by efflux transporters.

RESULTS

This article reviews a range of efflux transporter-based MDR models used to test the efficacy of compounds to overcome MDR in cancer. These models are classified as either in vitro or in vivo and are further categorised as the most basic, conventional models or more complex and advanced systems. Each model's origin, advantages and limitations, as well as specific efflux transporter-based MDR applications are discussed. Accordingly, future modifications to existing models or new research approaches are suggested to develop prototypes that closely resemble the true nature of multidrug resistant cancer in the human body.

CONCLUSIONS

It is evident from this review that a combination of both in vitro and in vivo preclinical models can provide a better understanding of cancer itself, than using a single model only. However, there is still a clear lack of progression of these models from basic research to high-throughput clinical practice.

Vitamin E D-alpha-tocopheryl polyethylene glycol 1000 succinate-conjugated liposomal docetaxel reverses multidrug resistance in breast cancer cells

Objectives

Multidrug resistance (MDR) remains a primary challenge in breast cancer treatment. In the present study, D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS)-coated docetaxel-loaded liposomes were developed as a novel drug delivery system to reverse MDR and enhance breast cancer therapy compared with the traditional liposomes, DSPE-mPEG-coated liposomes (stealth liposomes) and commercial Taxotere®.

Key findings

Liposomes were prepared by thin – film dispersion method. Evaluations were performed using human breast cancer MCF-7 and resistant MCF-7/ADR cells. The reversal multidrug-resistant effect was assessed by P-gp inhibition assay, cytotoxicity, cellular uptake and apoptosis assay.

Results

The TPGS-chol-liposomes were of an appropriate particle size (140.0 ± 6.0 nm), zeta potential (−0.196 ± 0.08 mv), high encapsulation efficiency (99.0 ± 0.9) and favourable in vitro sustained release. The TPGS-coated liposomes significantly improved cytotoxicity and increased the intracellular accumulation of docetaxel in both types of breast cancer cells. The TPGS-coated liposomes were confirmed to induce apoptosis via a synergistic effect between docetaxel and TPGS. It was demonstrated that TPGS enhanced the intracellular accumulation of drug by inhibiting overexpressed P-glycoprotein.

Conclusions

The TPGS-conjugated liposomes showed significant advantages in vitro compared with the PEG-conjugated liposomes. The TPGS-conjugated liposomes could reverse the MDR and enhance breast cancer therapy.

Fabrication of redox-responsive doxorubicin and paclitaxel prodrug nanoparticles with microfluidics for selective cancer therapy

Cancer is an exceptionally confounding disease that demands the development of powerful drug/drugs, without inducing heavy adverse side effects. Thus, different approaches have been applied to improve the targeted delivery of cancer drugs: for example by using nanocarriers. However, nanocarriers are foreign materials, which need further validation for their biocompatibility and biodegradability. In this study, we have chemically conjugated the hydrophilic anticancer drug doxorubicin (DOX) with the hydrophobic drug paclitaxel (PTX) through a redox-sensitive disulfide bond, abbreviated to DOX-S-S-PTX. Subsequently, due to its amphiphilic characterization, the prodrug can self-assemble into nanoparticles under microfluidic nanoprecipitation. These novel prodrug nanoparticles have a super-high drug loading degree of 89%, which is impossible to achieve by any nanocarrier systems, and can be tailored to 180 nm to deliver themselves to the target, and release DOX and PTX under redox conditions, which are often found in cancer cells. By evaluating cell viability in MDA-MB-231, MDA-MB-231/ADR and MEF cell lines, we observed that the prodrug nanoparticles effectively killed the cancer cells, and selectively conquered the MDA-MB-231/ADR. Meanwhile, MEF cells were spared due to their lack of a redox condition. The cell interaction results show that the reduced intermediate of the prodrug can also bind to parent drug biological targets. The hemolysis results show that the nanoparticles are biocompatible in blood. Computer modelling suggested that the prodrug is unlikely to bind to biological targets that parent drugs still strongly interact with. Finally, we confirm that the prodrug nanoparticles have no therapeutic effect in blood or healthy cells, but can selectively eliminate the cancer cells that meet the redox conditions to cleave the disulfide bond and release the drugs DOX and PTX.

A polymeric micelle with an endosomal pH-sensitivity for intracellular delivery and enhanced antitumor efficacy of hydroxycamptothecin

Amphiphilic poly(ethylene glycol)-imino-poly(benzyl-l-aspartate) (PIPA) and poly(ethylene glycol)-poly(benzyl-l-aspartate) (PPA) block copolymers were synthesized as pH-responsive and pH-nonresponsive copolymers, respectively. Polymer micelles were fabricated by the film dispersion method, and hydroxycamptothecin (HCPT) was physically encapsulated into the micelles. The average diameter of the HCPT-loaded PIPA micelles (PIPAH micelles) was approximately 230 nm, which was slightly smaller than that of the HCPT-loaded PPA micelles (PPAH micelles, approximately 260 nm). The drug-loading content and encapsulation efficiency of the PIPAH micelles (3.33% and 68.89%, respectively) were slightly higher than those of the PPAH micelles (2.90% and 59.68%, respectively). The PIPAH micelles exhibited better colloid stability, storage stability, and plasma stability than the PPAH micelles. Drug release from the PIPAH micelles with imino groups was pH dependent, and more than 75% or 65% of the loaded HCPT was released within 24 h in weakly acidic media (pH 5.0 or 6.0, respectively). An in vitro cell assay demonstrated that the pH-sensitive micelles exhibited potent suppression of cancer cell proliferation and little cytotoxicity on normal cells. Additionally, these micelles could be efficiently internalized by the tumor cells through macropinocytosis- and caveolin-mediated endocytotic pathways. HCPT-loaded micelles had longer circulation time than the HCPT solution in a pharmacokinetic study. In vivo antitumor experiments indicate that the PIPAH micelles had better antitumor efficacy than the pH-insensitive PPAH micelles and the HCPT solution. Therefore, the pH-responsive PIPAH micelles have great potential for high-efficiency delivery of HCPT. STATEMENT OF SIGNIFICANCE: In this study, a new type of pH-responsive amphiphilic copolymer, poly(ethylene glycol)-imino-poly(benzyl-l-aspartate) (PIPA) block copolymer, was synthesized. This copolymer had then self-assembled to form nanomicelles for tumor intracellular delivery of hydroxycamptothecin (HCPT) for the first time. In in vitro test, the PIPAH micelles exhibited adequate stability and pH-dependent drug release. To one's excitement, the PIPAH micelles exhibited better antitumor efficacy and biosafety than the pH-insensitive micelles (PPAH) and the HCPT solution in in vitro and in vivo antitumor experiments. Therefore, the pH-responsive micelles in this study have significant potential to be used for high-performance delivery of HCPT and potentially for the targeted delivery of other cancer therapeutic agents. The polymer designed in this study can be used as a carrier of poorly soluble drugs or other active ingredients.

Design and synthesis of mixed micellar system for enhanced anticancer efficacy of Paclitaxel through its co-delivery with Naringin

Emergence of multidrug resistance (MDR) has limited the success of chemotherapeutic agents. Reversal of drugs efflux systems through combination therapy has got wider attention for increasing anticancer drugs efficacy. This study aims at co-encapsulation of Paclitaxel with Naringin in mixed polymeric micelles for enhanced anticancer activity of the drug. Drug-loaded micelles were prepared using two different amphiphilic block co-polymers and were characterized for morphology, size, zeta potential, drug encapsulation, in vitro release and stability using atomic force microscope (AFM), zetasizer, UV spectrophotometer, and FT-IR. MTT assay and fluorescence microscopy were used for in vitro cytotoxicity and cellular uptake studies. Nano-size micelles with spherical morphology and negative charge encapsulated 76.52 ± 0.94% and 32.87 0.61% Paclitaxel and Naringin, respectively. The micelles were thermally stable and retained 87.05 ± 0.69% and 92.88 ± 2.17% Paclitaxel and Naringin upon one-month storage. Maximum drug release was achieved at fourth hour of the study for both the loaded drugs. Paclitaxel co-encapsulation with Naringin synergistically improved its intracellular uptake and 65% in vitro cytotoxicity against breast cancer cells was achieved at its lower dose of 15 µg/mL. Results suggest that co-encapsulation of Paclitaxel with Naringin in mixed micelles is an effective strategy for achieving its higher anticancer activity.

Improving the biopharmaceutical attributes of mangiferin using vitamin E-TPGS co-loaded self-assembled phosholipidic nano-mixed micellar systems

The current research work encompasses the development, characterization, and evaluation of self-assembled phospholipidic nano-mixed miceller system (SPNMS) of a poorly soluble BCS Class IV xanthone bioactive, mangiferin (Mgf) functionalized with co-delivery of vitamin E TPGS. Systematic optimization using I-optimal design yielded self-assembled phospholipidic nano-micelles with a particle size of < 60 nm and > 80% of drug release in 15 min. The cytotoxicity and cellular uptake studies performed using MCF-7 and MDA-MB-231 cell lines demonstrated greater kill and faster cellular uptake. The ex vivo intestinal permeability revealed higher lymphatic uptake, while in situ perfusion and in vivo pharmacokinetic studies indicated nearly 6.6- and 3.0-folds augmentation in permeability and bioavailability of Mgf. In a nutshell, vitamin E functionalized SPNMS of Mgf improved the biopharmaceutical performance of Mgf in rats for enhanced anticancer potency.

Self-assembled and pH-sensitive mixed micelles as an intracellular doxorubicin delivery system

Nanocarrier-based drug delivery systems have been explored extensively in cancer therapy. Among the vast number of different nanocarrier systems applied to deliver chemotherapeutics to cancer tumor, intelligent systems which deliver drug to various sites in the body have attracted considerable attentions. Finding a specific stimulant that triggers the carrier to release its payload in the target tissue is a key parameter for efficacy of delivery systems. Acidic pH of cancer tumor helps a pH-sensitive carrier to release drug at the tumor site. In this study, a pH-sensitive mixed micellar system was developed using Dextran-Stearic Acid (Dex-SA) and Dextran-Histidine (Dex-His) conjugated polymers to deliver doxorubicin (DOX) to cancer cells. Drug release from this micellar system showed higher release rate at acidic pH than that of in neutral environment, where the release was 56 and 76% at pH 7.4 and acidic pH, respectively. Finally, the in vitro cytotoxicity and cell uptake of DOX-loaded micelles and free DOX on U87 MG cell line showed that micellar systems had more anti-proliferation effect and uptake compared to free drug.

Rational Design of an Amphiphilic Chlorambucil Prodrug Realizing Self-Assembled Micelles for Efficient Anticancer Therapy

The application of anticancer drug chlorambucil (CLB) in chemotherapy is severely restricted by its insolubility, lability, and toxic side effects; therefore, it is challenging to realize a highly efficient anticancer therapy of chlorambucil. To solve the above drawbacks encountered by chlorambucil, herein we proposed an amphiphilic chlorambucil prodrug-based self-assembled micelle strategy to realize the highly efficient anticancer therapy of chlorambucil. 1,6-Hexanediamine hydrochloride (HDH) serving as the hydrophilic segment was covalently bound to hydrophobic CLB to prepare an amphiphilic prodrug CLB-HDH which could self-assemble into micelles in aqueous solution. These micelles can passively target tumor tissues via the enhanced permeability and retention (EPR) effect, leading to enhanced cellular internalization. Both the cytotoxicity assay in vitro and anticancer study in vivo confirmed the excellent therapeutic activity of CLB-HDH micelles in comparison with free chlorambucil. Moreover, the hemolysis examination and histological analysis demonstrated the designed CLB-HDH micelles are safe in drug delivery. Therefore, our designed amphiphilic prodrug CLB-HDH micelles bring new opportunity for chlorambucil clinical application to combat cancers.

Redox-responsive F127-folate/F127-disulfide bond-d-α-tocopheryl polyethylene glycol 1000 succinate/P123 mixed micelles loaded with paclitaxel for the reversal of multidrug resistance in tumors

Introduction

The development of nanodrug carriers utilizing tumor microenvironment has become a hotspot in reversing multidrug resistance (MDR).

Materials and methods

This study synthesized a redox-sensitive copolymer, Pluronic F127-disulfide bond-d-α-tocopheryl polyethylene glycol 1000 succinate (FSST), through the connection of the reduction-sensitive disulfide bond between F127 and d-α-tocopheryl polyethylene glycol 1000 succinate. This polymer could induce the elevation of reactive oxygen species (ROS) levels, ultimately resulting in cytotoxicity. Moreover, the redox-responsive mixed micelles, F127-folate (FA)/FSST/P123 (FFSSTP), based on FSST, Pluronic F127-FA, and Pluronic P123, were prepared to load paclitaxel (PTX).

Results

The in vitro release study demonstrated that FFSSTP/PTX accelerated the PTX release through the breakage of disulfide bond in reductive environment. In cellular experiment, FFSSTP/PTX induced significant apoptosis in PTX-resistant MCF-7/PTX cells through inhibiting adenosine triphosphate (ATP)-binding cassette proteins from pumping out PTX by interfering with the mitochondrial function and ATP synthesis. Furthermore, FFSSTP/PTX induced apoptosis through elevating the intracellular levels of ROS.

Conclusion

FFSSTP could become a potential carrier for the treatment of MDR tumors.