Rapid Drug Release Research Articles

Synergistic chemo-photothermal therapy of tumor by hollow carbon nanospheres

Combined use of different therapies is conducive to improve the effectiveness of cancer therapy. The chemo-photothermal therapy is commonly used in one nanocarrier to provide an excellent synergistic effect for cancer therapy over photothermal therapy (PTT) or chemotherapy alone. In this study, biocompatible and monodisperse hollow carbon nanospheres (HCNs) were developed as a multifunctional platform for the delivery of paclitaxel (PTX) and PTT of cancer simultaneously. The mesoporous HCNs have large pore volume and proper channels for loading and release of PTX. Upon near-infrared (NIR) laser illumination, the photothermal mediator of HCNs could effectively convert absorbed light into heat, which triggered rapid release of chemotherapeutic drug from HCNs through dissociating the interactions between PTX and HCNs by heat energy. A large number of tumor cells were significantly destroyed when hct116 cells treated with PTX@HCNs were irradiated, which was mainly attribute to the synergistic result of HCNs-mediated photothermal damage and cytotoxicity of light-triggered PTX release.

CuS-Based Theranostic Micelles for NIR-Controlled Combination Chemotherapy and Photothermal Therapy and Photoacoustic Imaging.

Cancer remains a major threat to human health due to low therapeutic efficacies of currently available cancer treatment options. Nanotheranostics, capable of simultaneous therapy and diagnosis/monitoring of diseases, has attracted increasing amounts of attention, particularly for cancer treatment. In this study, CuS-based theranostic micelles capable of simultaneous combination chemotherapy and photothermal therapy (PTT), as well as photoacoustic imaging, were developed for targeted cancer therapy. The micelle was formed by a CuS nanoparticle (NP) functionalized by thermosensitive amphiphilic poly(acrylamide-acrylonitrile)-poly(ethylene glycol) block copolymers. CuS NPs under near-infrared (NIR) irradiation induced a significant temperature elevation, thereby enabling NIR-triggered PTT. Moreover, the hydrophobic core formed by poly(acrylamide-acrylonitrile) segments used for drug encapsulation exhibited an upper critical solution temperature (UCST; ∼38 °C), which underwent a hydrophobic-to-hydrophilic transition once the temperature rose above the UCST induced by NIR-irradiated CuS NPs, thereby triggering a rapid drug release and enabling NIR-controlled chemotherapy. The CuS-based micelles conjugated with GE11 peptides were tested in an epidermal growth factor receptor-overexpressing triple-negative breast cancer model. In both two-dimensional monolayer cell and three-dimensional multicellular tumor spheroid models, GE11-tagged CuS-based micelles under NIR irradiation, enabling the combination chemotherapy and PTT, exhibited the best therapeutic outcome due to a synergistic effect. These CuS-based micelles also displayed a good photoacoustic imaging ability under NIR illumination. Taken together, this multifunctional CuS-based micelle could be a promising nanoplatform for targeted cancer nanotheranostics.

A nanoliposome-based photoactivable drug delivery system for enhanced cancer therapy and overcoming treatment resistance.

Recently, stimuli-responsive drug delivery systems (DDSs) with high spatial/temporal resolution bring many benefits to cancer treatment. However, cancer cells always develop ways to resist and evade treatment, ultimately limit the treatment efficacy of the DDSs. Here, we introduce photo-activated nanoliposomes (PNLs) that impart light-induced cytotoxicity and reversal of drug resistance in synchrony with a photoinitiated and rapid release of antitumor drug. The PNLs consist of a nanoliposome doped with a photosensitizer (hematoporphyrin monomethyl ether [HMME]) in the lipid bilayer and an antitumor drug doxorubicin (DOX) encapsulated inside. PNLs have several distinctive capabilities: 1) carrying high loadings of DOX and HMME and releasing the payloads in a photo-cleavage manner with high spatial/temporal resolution at the site of actions via photocatalysis; 2) reducing drug efflux in MCF-7/multidrug resistance cells via decreasing the level of P-glycoprotein induced by photodynamic therapy (PDT); 3) accumulating in tumor site taking advantage of the enhanced permeability and retention effect; and 4) combining effective chemotherapy and PDT to exert much enhanced anticancer effect and achieving significant tumor regression in a drug-resistant tumor model with little side effects.

Comparison of Biomimetic Block Copolymer Micelles as Drug Carriers for Cancer Therapy.

Zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is a promising alternative for poly(ethylene glycol) (PEG) as micelle shell-forming block. Three different PMPC-based polymeric micelles were designed and compared with PEGylated micelles. Cholesterol-conjugated and disulfide-modified poly(D, L-lactide)-SS-poly(2-methacryloyloxyethyl phosphorylcholine) (CPLA-SS-PMPC) micelles, cholesterol-conjugated CPLA-PMPC micelles without disulfides, and PLA-PMPC micelles without cholesterol-conjugation were compared to PLA-PEG micelles. These PMPC-based micelles showed better hydrophilicity and less protein adsorption. In cellular uptake evaluation, PMPC-based micelles exhibited much better cellular uptake than that of the PLA-PEG, which might reflect strong interaction between the biomimetic PMPC surface and the cellular membrane. In addition, although there was no statistical difference in cellular internalization behavior among these three PMPC-based micelles, the anticancer activity of paclitaxel (PTX)-loaded CPLA-SS-PMPC micelles was significantly higher than those of the other two kinds of micelles. This superiority was attributed to the rapid release of the anticancer drug under the redox environment inside cancer cells.

Redox-Sensitive Polymeric Micelles Based on Tetraphenylethylene-Conjugated Copolymer for Aggregation-Induced Emission Active Imaging and Drug Delivery.

Intelligent nanocarriers for efficient drug delivery and bioimaging application are urgently demand. Herein, paclitaxel (PTX)-encapsulated redox-sensitive polymeric micelles based on tetraphenylethylene (TPE)-conjugated poly(D, L-lactide)-disulfide-poly(methacryloyloxyethyl phosphorylcholine) (TPE-PLA-SS-PMPC) copolymer has been developed for combined cancer therapy and aggregation induced emission (AIE) imaging. These biomimetic TPE-PLA-SS-PMPC micelles exhibit great biocompatibility and remarkable AIE features, showing great potential for bioimaging applications. PTX is loaded during the self-assembly process, and these drug-loaded micelles can disassemble quickly in the medium containing 10 mM glutathione to trigger rapid drug release and great growth inhibition of tumor cells. Moreover, these micelles can also be traced via fluorescent imaging of these AIE micelles. AIE active imaging and tumor cell growth inhibition, as well as excellent biocompatibility make these smart biomimetic micelles highly attractive as a prominent candidate for chemotherapy and bioimaging.

In vitro curcumin delivery and antibacterial activity of RuS2 and RuO2 nanoparticles loaded chitosan biopolymer

In this work, RuS2 and RuO2 nanoparticles loaded chitosan (Chitosan was extracted from Lobsters shells of Persian Gulf, IR. Iran) was prepared and characterized via FE‐SEM, EDS and FT‐IR analysis. FESEM showed the formation of spherical nanoparticles in size ranging of 20 to 100 mm. Subsequently, the role of these new materials as curcumin drug carrier and in vitro release of curcumin in simulated body fluid (SBF) solution (pH 7.4) were studied. RuS2‐NPs‐CS than to RuO2‐NPs‐CS showed higher drug loading efficiency (>91%) and rapid (<90 min) curcumin drug release in SBF solution. Also, antibacterial activity of RuS2‐NPs‐CS and RuO2‐NPs‐CS in presens and absence of Rosemary extracts against the gram negative bacteria Pseudomonas aeruginosa (PAO 1) was evaluated by detection of minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC). MIC of RuS2‐NPs‐CS, RuO2‐NPs‐CS and Rosemary extracts on Pseudomonas aeruginosa strains were found to be 50 mg/ml, 50 mg/ml and 1250 mg/ml, respectively. The synergistic effect of these materials for inhibition of PAO 1 growth showed that mixture of RuS2‐NPs‐CS and Rosemary extracts has a better efficiency than to other mixture materials.

Formulation of 3D Printed Tablet for Rapid Drug Release by Fused Deposition Modeling: Screening Polymers for Drug Release, Drug-Polymer Miscibility and Printability

The primary aim of this study was to identify pharmaceutically acceptable amorphous polymers for producing 3D printed tablets of a model drug, haloperidol, for rapid release by fused deposition modeling. Filaments for 3D printing were prepared by hot melt extrusion at 150°C with 10% and 20% w/w of haloperidol using Kollidon® VA64, Kollicoat® IR, Affinsiol™15 cP, and HPMCAS either individually or as binary blends (Kollidon® VA64 + Affinisol™ 15 cP, 1:1; Kollidon® VA64 + HPMCAS, 1:1). Dissolution of crushed extrudates was studied at pH 2 and 6.8, and formulations demonstrating rapid dissolution rates were then analyzed for drug-polymer, polymer-polymer and drug-polymer-polymer miscibility by film casting. Polymer-polymer (1:1) and drug-polymer-polymer (1:5:5 and 2:5:5) mixtures were found to be miscible. Tablets with 100% and 60% infill were printed using MakerBot printer at 210°C, and dissolution tests of tablets were conducted at pH 2 and 6.8. Extruded filaments of Kollidon® VA64-Affinisol™ 15 cP mixtures were flexible and had optimum mechanical strength for 3D printing. Tablets containing 10% drug with 60% and 100% infill showed complete drug release at pH 2 in 45 and 120 min, respectively. Relatively high dissolution rates were also observed at pH 6.8. The 1:1-mixture of Kollidon® VA64 and Affinisol™15 cP was thus identified as a suitable polymer system for 3D printing and rapid drug release.

Effect of semicrystalline polymers on self-emulsifying solid dispersions of nateglinide: in vitro and in vivo evaluation

This study was undertaken to improve solubility and bioavailability of nateglinide by preparation of stable self-emulsifying solid dispersions (SESDs). The influence of semicrystalline polymers (poloxamer 407, gelucire 50/13) and method of preparation on dissolution behavior, in vivo performance and stability of nateglinide SESDs were investigated. After optimization, SESDs were prepared at 1:5 weight ratio of nateglinide and polymer individually. All the SESDs were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. Aqueous solubility of nateglinide was enhanced by 91.82-fold. The SESDs (poloxamer 407-based solid dispersions) achieved rapid and complete drug release (∼100% within 45 min) at pH 2. The improved dissolution appeared to be well correlated with the enhanced bioavailability of nateglinide in rabbits. After oral administration of SESDs (poloxamer 407-based solid dispersions), Cmax and AUC of nateglinide were increased by ∼2.92 and 1.77-folds, respectively, signifying the effectiveness of solid dispersions to improve the bioavailability of nateglinide. Stability during storage was established to show prevention of recrystallization. In conclusion, SESDs with poloxamer 407 in solvent method appeared to be an economic and promising technique to improve the dissolution, bioavailability, and stability of nateglinide.

Stepwise pH/reduction-responsive polymeric conjugates for enhanced drug delivery to tumor

In this research, a charge-conversional polymer, poly-l-lysine-lipoic acid (PLL-LA), was prepared by dimethylmaleic anhydride (DA) modification and applied as a carrier with enhanced cell internalization and intracellular pH- and reduction-triggered doxorubicin (Dox) release. The surface charge of dimethylmaleic anhydride-poly-l-lysine-lipoic acid micelles (DA-PLL-LA) was negative at physiological pH and reversed to positive at the extracellular and intracellular pH of cancer cells. At tumor extracellular pH of 6.8, the conjugates underwent a rapid charge-reversible process with almost 80% DA cleavage within 2h, and then endocytosed into the endo/lysosomes more rapidly than at physiological pH of 7.4. The Dox/DA-PLL-LA micelles (Dox-micelles) demonstrated a sustained drug release in vitro under physiological condition, and rapid Dox release was triggered by both extracellular pH and high-concentration reducing glutathione. The Dox-micelles also exhibited enhanced internalization at extracellular pH, rapid intracellular drug release, and improved cytotoxicity against A549 cells in vitro. Excellent tumor-penetrating efficacy was also found in A549 tumor spheroids and solid tumor slices. Moreover, the DA-PLL-LA micelles exhibited excellent tumor-targeting ability in tumor tissues and excellent antitumor efficacy and low systemic toxicity in breast tumor-bearing mice. Therefore, the DA-PLL-LA micelles demonstrated great potential for targeted and efficient drug delivery in cancer treatments.

Sustained-releasing hollow microparticles with dual-anticancer drugs elicit greater shrinkage of tumor spheroids.

Polymeric particulate delivery systems are vastly explored for the delivery of chemotherapeutic agents. However, the preparation of polymeric particulate systems with the capability of providing sustained release of two or more drugs is still a challenge. Herein, poly (D, L-lactic-co-glycolic acid, 50:50) hollow microparticles co-loaded with doxorubicin and paclitaxel were developed through double-emulsion solvent evaporation technique. Hollow microparticles were formed through the addition of an osmolyte into the fabrication process. The benefits of hollow over solid microparticles were found to be higher encapsulation efficiency and a more rapid drug release rate. Further modification of the hollow microparticles was accomplished through the introduction of methyl-β-cyclodextrin. With this, a higher encapsulation efficiency of both drugs and an enhanced cumulative release were achieved. Spheroid study further demonstrated that the controlled release of the drugs from the methyl-β-cyclodextrin -loaded hollow microparticles exhibited enhanced tumor regressions of MCF-7 tumor spheroids. Such hollow dual-drug-loaded hollow microparticles with sustained releasing capabilities may have a potential for future applications in cancer therapy.

Electrospun gelatin/sodium bicarbonate and poly(lactide-co-ε-caprolactone)/sodium bicarbonate nanofibers as drug delivery systems

In this work, we report electrospun nanofibers made of model hydrophobic (poly(lactide-co-ε-caprolactone); PLCL) and hydrophilic (gelatin) polymers. We explored the effect on drug release of the incorporation of sodium bicarbonate (SB) into these fibers, using the potent antibacterial agent ciprofloxacin as a model drug. The fibers prepared are smooth and have relatively uniform diameters lying between ca. 600 and 850nm. The presence of ciprofloxacin in the fibers was confirmed using IR spectroscopy. X-ray diffraction showed the drug to be incorporated into the fibers in the amorphous form. In vitro drug release studies revealed that, as expected, more rapid drug release was seen with gelatin fibers than those made of PLCL, and a greater final release percentage was obtained. The inclusion of SB in the gelatin fibers imparts them with pH sensitivity: gelatin/SB fibers showed faster release at pH5 than pH7.4, while fibers without SB gave the same release profiles at both pHs. The PLCL fibers have no pH sensitivity, even when SB was included, as a result of their hydrophobic structure precluding the ingress of solvent. In vitro cell culture studies showed that all the fibers are able to promote cell proliferation. The ciprofloxacin loaded fibers are effective in inhibiting Escherichia coli and Staphylococcus aureus growth in antibacterial tests. Thus, the gelatin-based fibers can be used as pH-responsive drug delivery systems, with potential applications for instance in the treatment of tumor resection sites. Should these become infected, the pH would drop, resulting in ciprofloxacin being released and the infection halted.

Drug delivery and cytocompatibility of ciprofloxacin loaded gelatin nanofibers-coated Mg alloy

In this study, gelatin-ciprofloxacin (Gel-Cip) nanofibers containing various amounts of Cip (0, 2, 4 and, 8wt%) were fabricated on the surface of Mg-1Ca alloy via an electrospinning process. Microscopic characterization indicated a porous network structure with fiber diameters in the range of 150–170nm. Prolonged drug release was attained from Gel-Cip nanofibers coating along with initial rapid drug release of around 20–22% during 12h, followed by a slow release stage that can effectively control the infection. The incorporation of 2–4wt% Cip into Gel nanofibers coating significantly increased the antibacterial performance and corrosion resistance of the uncoated Mg-Ca alloy without showing an inhibitory influence on the cytocompatibility characteristic. Hence, it is potentially appropriate as the novel electrospun nanofibers coating material for bone regeneration application.

Chitosan nanofilm and electrospun nanofiber for quick drug release in the treatment of Alzheimer’s disease: In vitro and in vivo evaluation

Chitosan micro sized ODF (CBF), chitosan nano sized ODF (CNF) and chitosan nanofiber (CNfib) were prepared to release the donepezil drug quickly for Alzheimer’s disease. CNF and CNfib were prepared from ionic gelation technique and electro-spinning process which were further examined under in vitro and in vivo animal model studies. Good thermal stability of CNfib (450°C) when compared to CBF (325°C) and CNF (305°C). The particle size was below 150nm in diameter for CNfib and 250nm in diameter for CNF4 from TEM technique. In vitro antimicrobial activities for ODF and nanofibers were conducted by well diffusion method against Gram +ve and Gram −ve bacteria after 24h of incubation. From the in vitro release profile, the CNfib was competently showed rapid release of drug up to 97% than the thin film of CBF2 and CNF4 respectively in the initial period of 10min. In vivo animal model studies demonstrated that the drug reached the maximum concentration within 3.5h for chitosan nanofiber and nanofilm (CNF4). The chitosan nanofiber has given significantly faster absorption rate [1860.5ng/ml of AUC(0-∞)] and the mean total area under curve was 161.71% on contrasted with chitosan nanofilm (CNF4).

Inhibition of cell proliferation through an ATP-responsive co-delivery system of doxorubicin and Bcl-2 siRNA.

Herein, DNA duplex was constructed through the hybridization of adenosine triphosphate (ATP)-responsive aptamer and its cDNA in which GC-rich motif could be used to load doxorubicin (DOX), and then, cationic polymer PEI25K was used as a carrier to simultaneously condense DOX-Duplex and Bcl-2 siRNA to prepare the ternary nanocomplex polyethylenimine (PEI)/DOX-Duplex/siRNA. The ATP concentration gradient between the cytosol and extracellular environment could achieve the stable loading of DOX in duplex and the rapid drug release in an ATP-responsive manner. Using human prostate tumor cell line PC-3 as a model, an obvious induction of cell proliferation could be detected with a cell viability of 53.3%, which was stronger than single cargo delivery, indicating the synergistic effect between these two components. The enhanced anti-proliferative effect of ternary nanocomplex could be attributed to the improved induction of cell apoptosis in a mitochondria-mediated pathway and cell-cycle arrest at the G2 phase. Overall, the ATP-responsive nanocarrier for co-delivering DOX and Bcl-2 siRNA has been demonstrated to be a smart delivery system with favorable anti-proliferative effect, especially for solving the multidrug resistance of tumors.

Microparticles prepared with 50–190 kDa chitosan as promising non-toxic carriers for pulmonary delivery of isoniazid

Chitosan biocompatibility and mucoadhesiveness make it an ideal polymer for antituberculotic drugs microcapsulation for pulmonary delivery. Yet, previous study indicated toxicity problems to J-774.1-cells treated with some medium molecular weight (190–310kDa) chitosan microparticles. As polymer molecular weight is a crucial factor to be considered, this paper describes the preparation and characterization of chitosan (50–190kDa) microparticles containing isoniazid (INH). Cytotoxicity assays were also performed on murine peritoneal (J-774.1) and alveolar (AMJ2-C11) macrophages cell lines, followed by cytokines detection from AMJ2-C11 cells. Spray-drying process produced mucoadhesive microparticles from 3.2μm to 3.9μm, entrapping more than 89% of the drug and preserving their chemical stability. Drug release behavior could be controlled by the use of cross-linked or uncross-linked chitosan, the latter leading to a rapid drug release. Mucoadhesive potential of the microparticles was characterized following in vitro and ex vivo assays. Finally, a significant reduction on toxicity against peritoneal macrophages and no toxic effect on alveolar macrophages with use of such microparticles were observed. In conclusion, 50–190kDa chitosan microparticles may act as promising non-cytotoxic carriers for pulmonary delivery of INH showing marked alveoli macrophage activation.

NIR responsive liposomal system for rapid release of drugs in cancer therapy

To design a rapid release liposomal system for cancer therapy, a NIR responsive bubble-generating thermosensitive liposome (BTSL) system combined with photothermal agent (Cypate), doxorubicin (DOX), and NH4HCO3 was developed. Cypate/DOX-BTSL exhibited a good aqueous stability, photostability, and photothermal effect. In vitro release suggested that the amounts of DOX released from BTSL were obviously higher than that of (NH4)2SO4 liposomes at 42°C. After NIR irradiation, the hyperthermic temperature induced by Cypate led to the decomposition of NH4HCO3 and the generation of a large number of CO2 bubbles, triggering a rapid release of drugs. Confocal laser scanning microscope and acridine orange staining indicated that Cypate/DOX-BTSL upon irradiation could facilitate to disrupt the lysosomal membranes and realize endolysosomal escape into cytosol, improving the intracellular uptake of DOX clearly. MTT and trypan blue staining implied that the cell damage of Cypate/DOX-BTSL with NIR irradiation was more severe than that in the groups without irradiation. In vivo results indicated that Cypate/DOX-BTSL with irradiation could dramatically increase the accumulation of DOX in tumor, inhibit tumor growth, and reduce systemic side effects of DOX. These data demonstrated that Cypate/DOX-BTSL has the potential to be used as a NIR responsive liposomal system for a rapid release of drugs in thermochemotherapy.

In vitro and in vivo behavior of ground tadalafil hot-melt extrudates: How the carrier material can effectively assure rapid or controlled drug release

Different types of ground hot-melt extrudates loaded with 10, 20 or 30 % of the poorly water-soluble drug tadalafil were prepared and characterized in vitro and in vivo (in rats). Soluplus was used as an amorphous carrier material, whereas mannitol and lactitol were studied as crystalline matrix formers. The systems were characterized using X-ray powder diffraction, thermogravimetric analysis coupled with quadruple mass spectrometry, differential scanning calorimetry, X-ray computed microtomography, in vitro drug release measurements and monitoring of drug plasma levels upon oral administration to rats. The pure drug substance and physical mixtures of tadalafil with the carrier materials were used as references. Importantly, the bioavailability of this poorly water-soluble drug could be substantially increased with the proposed formulations, and the in vitro and in vivo release rates could be effectively adjusted by choosing the appropriate type of carrier material: Whereas mannitol-based ground hot-melt extrudates rapidly released the drug and led to an early rise in drug plasma concentrations, Soluplus-based systems released tadalafil more slowly, resulting in delayed plasma peaks. These behaviors could be explained by the rapid disintegration/dissolution of the porous mannitol-based formulations, whereas Soluplus significantly swelled and the dissolved drug had to diffuse through the polymeric network prior to release. Blending these formulations can be expected to allow providing elevated drug concentrations in vivo during prolonged periods of time upon one single administration with a rapid onset of drug action.

Polymersomes with Rapid K+-Triggered Drug-Release Behaviors.

A novel type of smart polymersomes with rapid K+-triggered drug-release properties is developed in this work. Block copolymers with biocompatible poly(ethylene glycol) (PEG) as the hydrophilic block and poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (PNB) copolymer as the K+-responsive block are successfully synthesized. Because of the presence of 18-crown-6 units, the PEG-b-PNB block copolymers exhibit excellent K+-dependent phase-transition behaviors, which show a hydrophilic-hydrophobic state in simulated extracellular fluid and present a hydrophilic-hydrophilic state in simulated intracellular fluid. Polymersomes with regular spherical shape and good monodispersity are prepared by the self-assembly of the PEG-b-PNB block copolymers. Both hydrophilic fluorescein isothiocyanate-dextran and hydrophobic doxorubicin are selected as model drugs and are successfully encapsulated into the PEG-b-PNB polymersomes. After being placed in a simulated intracellular fluid with high K+ concentration, the PEG-b-PNB polymersomes immediately disassemble accompanied by the rapid and complete release of drugs. Such K+-responsive polymersomes with the desired drug-release properties provide a novel strategy for advanced intracellular drug delivery and release, which can enhance the safety and efficacy of cancer therapy.

PH-responsive nanoparticle assembly from peptide amphiphiles for tumor targeting drug delivery

In this paper, the peptide amphiphiles (PA) which consists of RGDSEEEEEEEEEEK as pH-sensitive segment and stearic acid as hydrophobic segment named RGDS-E10-Lys(C18) was successfully synthesized. TEM images showed that uniformly dispersed nanoparticles could be formed by PA molecules in pH 7.4 medium, however, disintegrated in pH 5.0 medium. Circular dichroism (CD) spectrum indicated that polypeptide adopted a random-coil conformation in neutral medium (pH 7.4). The CD signal was significantly attenuate for decreased solubility of PA in medium with pH 5.0. As expected, the prepared RGDS-E10-Lys(C18) assembly showed high pH-sensitive property which demonstrated a much more rapid drug release from micelles in tumor tissue (acidic environment) than in physiological environment (neutral environment). After DOX-loaded micelles incubated with tumor cells, the cytotoxicity of the micelles against Hela cells was increased obviously, indicating the great potential of micelles developed here as promising vehicle for targeted pH-responsive drug delivery.

Programmable co-delivery of the immune checkpoint inhibitor NLG919 and chemotherapeutic doxorubicin via a redox-responsive immunostimulatory polymeric prodrug carrier

To achieve synergistic therapeutic efficacy and prevent cancer relapse, chemotherapy and immunotherapy have been combined as a new modality for tumor treatment. In this work, we designed a redox-responsive immunostimulatory polymeric prodrug carrier, PSSN10, for programmable co-delivery of an immune checkpoint inhibitor NLG919 (NLG) and a chemotherapeutic doxorubicin (DOX). NLG-containing PSSN10 prodrug polymers were self-assembled into nano-sized micelles that served as a carrier to load DOX (DOX/PSSN10 micelles). DOX/PSSN10 micelles displayed spherical morphology with a size of ∼170 nm. DOX was effectively loaded into PSSN10 micelles with a loading efficiency of 84.0%. In vitro DOX release studies showed that rapid drug release could be achieved in the highly redox environment after intracellular uptake by tumor cells. In 4T1.2 tumor-bearing mice, DOX/PSSN10 micelles exhibited greater accumulation of DOX and NLG in the tumor tissues compared with other organs. The PSSN10 carrier dose-dependently enhanced T-cell immune responses in the lymphocyte-Panc02 co-culture experiments, and significantly inhibited tumor growth in vivo. DOX/PSSN10 micelles showed potent cytotoxicity in vitro against 4T1.2 mouse breast cancer cells and PC-3 human prostate cancer cells comparable to that of DOX. In 4T1.2 tumor-bearing mice, DOX/PSSN10 mixed micelles (5 mg DOX/kg, iv) was more effective than DOXIL (a clinical formulation of liposomal DOX) or free DOX in inhibiting the tumor growth and prolonging the survival of the treated mice. In addition, a more immunoactive tumor microenvironment was observed in the mice treated with PSSN10 or DOX/PSSN10 micelles compared with the other treatment groups. In conclusion, systemic delivery of DOX via PSSN10 nanocarrier results in synergistic anti-tumor activity.