Intracellular Delivery Of Doxorubicin Research Articles

Hyaluronic acid-coated silver nanoparticles releasing Doxorubicin for combinatorial antitumor therapy

Although various nanocarriers have been developed to deliver anticancer drugs to the target tumors, it is still remaining great challenges, including burst release, non-specific targetability and insufficient therapeutic efficacy. Herein, we prepared a multifunctional nanoparticle composed of Ag core and hyaluronic acid shell (Ag NPs@HA) for stimultaneously intracellular delivery of Doxorubicin (DOX) and Ag NPs to improve the anticancer therapeutic efficacy. For our approach, Ag NPs was simply synthesized via the redox reaction between Ag+ ions and catechol group of functional HA, and DOX was subsequently loaded into the HA-coated Ag NPs through the interaction between the remaining catechol groups and DOX (Ag NPs@HA/DOX). The particles exhibited uniform morphology, good biocompatibility to normal cells, and pH-sensitive drug release. Notably, thanks to the specific interaction of HA and CD44 receptor-overexpressing cancer cells, Ag NPs@HA/DOX could dramatically improve the anti-tumor efficacy in vitro as well as in vivo mimicking 3D spheroid model, compared to the free DOX. Moreover, Ag NPs@HA/DOX exhibited superior tumor supression in vivo on a HELA-xenografted mouse model, while minimizing the systemic toxicity of free DOX. From the obtained results, we suggest Ag NPs@HA as potential nanocarrier for targeting delivery of various therapeutic drugs in anticancer therapy.

α-Tocopherol Polyethylene Glycol 1000 Succinate-Based Cationic Liposome for the Intracellular Delivery of Doxorubicin in MDA-MB-231 Triple-Negative Breast Cancer Cell Line.

Present research work reports the development of doxorubicin (DOX) loaded α-tocopherol polyethylene glycol 1000 succinate (TPGS)-coated cationic liposomes. The developed formulation was evaluated for its anticancer potential and intracellular uptake against the MDA-MB-231 breast cancer cell line. Moreover, hemocompatibility studies were also done on human blood red blood cells for the determination of blood compatibility. The prepared doxorubicin-loaded TPGS liposomes (DOX-LIPO-TPGS) and doxorubicin-loaded cationic liposomes (DOX-LIPO+-TPGS) reveal vesicle size (177.5 ± 2.5 and 201.7 ± 2.3 nm), polydispersity index (0.189 ± 0.01 and 0.218 ± 0.02), zeta potential (-36.9 ± 0.7 and 42 ± 0.9 mv), and % entrapment efficiency (65.88% ± 3.7% and 74.5% ± 3.9%). Furthermore, in vitro, drug release kinetics of the drug alone and drug from formulation shows sustained release behavior of developed formulation with 99.98% in 12 h and 80.98% release of the drug in 72 h, respectively. In addition, cytotoxicity studies and cellular DOX uptake on the MDA-MB-231 breast cancer cell line depict higher cytotoxic and drug uptake potential with better hemocompatibility of DOX-LIPO+-TPGS with respect to DOX. The data from the study revealed that TPGS plays an important role in enhancing the formulation's quality attributes like stability, drug release, cytotoxicity, and hemocompatibility behavior. This may serve that TPGS-coated cationic liposome as a vital candidate for the treatment of cancer and drug delivery in case of breast cancer.

Multifunctional nanotherapeutics for intracellular trafficking of doxorubicin against breast cancer.

Aims: To develop an estrone-targeted d-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS)-based liposomal system for enhanced intracellular delivery of doxorubicin (DOX). Materials & methods: Zetasizer, transmission electron microscopy, energy dispersive x-ray, Fourier-transform infrared spectroscopy, differential scanning calorimetry, x-ray diffraction, confocal laser scanning microscopyand FACS analysis were used for formulation characterization and evaluation. Results: TheDOX-LIPO-TPGS and DOX-LIPO-TPGS-estrone formulations had vesicle sizes (117.6±3.51;144±5.00nm), zeta potential (-36.4±0.75; -35.8±0.76), polydispersity index (0.123±0.005;0.169±0.005) and percent entrapment efficiency (73.56±3.55; 77.16±3.83%) with improved cytotoxicity andcellular uptake, confirming thetargeted potential of thedeveloped formulations. Conclusion: The results suggest that the developed liposomal formulationwith desired characteristics is potentially capable of nonimmunogenic, site-specific drug delivery to targeted cancer sites and reduced DOX-associated cardiac toxicity.

Impact of the Core Architecture of Dual pH-Responsive Polymer Nanoparticles on Intracellular Delivery of Doxorubicin

Impact of the Core Architecture of Dual pH-Responsive Polymer Nanoparticles on Intracellular Delivery of Doxorubicin

Intrafollicular injection of nanomolecules for advancing knowledge on folliculogenesis in livestock

Despite the progress in assisted reproductive techniques, there is still a lack of rapid and minimally invasive in situ approaches for further enhancements of female fertility. Therefore, we synthesized clinically relevant liposome nanoparticles for ovarian intrafollicular injection to allow in vivo cellular imaging for future drug delivery, using the mare as an animal model. Ovarian follicles of living mares were injected in vivo with fluorescently labeled liposomes. Samples of the follicular wall (mural granulosa, theca interna, and theca externa), granulosa cells, and follicular fluid were harvested 24 h post-injection through the follicle wall biopsy (FWB), flushing, and aspiration techniques, respectively, using a transvaginal ultrasound-guided approach. In parallel, post-mortem dissected, and cultured porcine antral follicles were microinjected with doxorubicin-encapsulated liposomes to assess intracellular delivery potential. All injected mare and pig follicles were macroscopically healthy, and fluorescence imaging revealed successful intrafollicular binding to mural granulosa cells and progressive migration of liposomes to other follicle cell layers (theca interna, and theca externa), regardless of the follicle size. Intracellular delivery of doxorubicin was confirmed in all porcine follicle wall cell types. We conclude that the intrafollicular injection of nanomolecules is a promising approach for real-time monitoring of intrafollicular processes and potential utilization of in vivo cellular drug delivery to assist in follicle disease treatments and fertility improvement.

Glutathione-depleted and cancer-targeted nanocapsules encapsulating bimetallic oxide nanoparticles for enhanced chemo-sonodynamic therapy

Sonodynamic therapy (SDT) has emerged as a promising noninvasive therapeutic modality due to its deep tissue penetration depth. Herein, biodegradable poly(lactic-co-glycolic acid) (PLGA) nanocapsules encapsulating oxygen-deficient MnWOx nanoparticles (NPs) and doxorubicin (DOX) were fabricated for chemo-sonodynamic combination therapy against cancer. To achieve cancer-targeted chemo-SDT, PLGA was conjugated to a cancer-targeting biotin through poly(ethylene glycol) (PEG). Biotin-PEG-PLGA (BP-PLGA) nanocapsules encapsulating DOX and hydrophobic MnWOx NPs (BP-PLGA-DOX@MnWOx) exhibited high physiological stability and pH-responsive drug release. The oxygen-deficient MnWOx NPs enabled US-triggered generation of singlet oxygen and hydroxyl radicals owing to their oxygen-deficient structures that prevent electron–hole recombination. Glutathione (GSH) depletion by MnWOx-loaded PLGA nanocapsules was observed in MCF-7 human breast cancer cells, which leads to augmented intracellular ROS levels and sonodynamic effects. Notably, BP-PLGA-DOX@MnWOx greatly improved cellular uptake by breast cancer cells, resulting in efficient intracellular delivery of DOX and MnWOx NPs. As a result, BP-PLGA-DOX@MnWOx exhibited efficient and cancer-targeted cytotoxicity in MCF-7 cells upon US irradiation. This study demonstrates that BP-PLGA-DOX@MnWOx nanocapsules are promising cancer-targeting nanosonosensitizers for efficient chemo-sonodynamic cancer therapy.

Bone mineral: A trojan horse for bone cancers. Efficient mitochondria targeted delivery and tumor eradication with nano hydroxyapatite containing doxorubicin

Efficient systemic pharmacological treatment of solid tumors is hampered by inadequate tumor concentration of cytostatics necessitating development of smart local drug delivery systems. To overcome this, we demonstrate that doxorubicin (DOX), a cornerstone drug used for osteosarcoma treatment, shows reversible accretion to hydroxyapatite (HA) of both nano (nHA) and micro (mHA) size. nHA particles functionalized with DOX get engulfed in the lysosome of osteosarcoma cells where the acidic microenvironment causes a disruption of the binding between DOX and HA. The released DOX then accumulates in the mitochondria causing cell starvation, reduced migration and apoptosis. The HA+DOX delivery system was also tested in-vivo on osteosarcoma bearing mice. Locally delivered DOX via the HA particles had a stronger tumor eradication effect compared to the controls as seen by PET-CT and immunohistochemical staining of proliferation and apoptosis markers. These results indicate that in addition to systemic chemotherapy, an adjuvant nHA could be used as a carrier for intracellular delivery of DOX for prevention of tumor recurrence after surgical resection in an osteosarcoma. Furthermore, we demonstrate that nHA particles are pivotal in this approach but a combination of nHA with mHA could increase the safety associated with particulate nanomaterials while maintaining similar therapeutic potential.

Smart Vitamin Micelles as Cancer Nanomedicines for Enhanced Intracellular Delivery of Doxorubicin.

Chemotherapy is one of the most effective treatments for cancer. However, intracellular delivery of many anticancer drugs is hindered by their hydrophobicity and low molecular weight. Here, we describe highly biocompatible and biodegradable amphiphilic vitamin conjugates comprising hydrophobic vitamin E and hydrophilic vitamin B labeled with dual pH and glutathione-responsive degradable linkages. Vitamin-based micelles (vitamicelles), formed by self-assembly in aqueous solutions, were optimized based on their stability after encapsulation of doxorubicin (DOX). The resulting vitamicelles have great potential as vehicles for anticancer drugs because they show excellent biocompatibility (>94% after 48 h of incubation) and rapid biodegradability (>90% after 2.5 h). Compared with free DOX, DOX-loaded vitamicelles showed a markedly enhanced anticancer effect as they released the drug rapidly and inhibited drug efflux out of cells efficiently. By exploiting these advantages, this study not only provides a promising strategy for circumventing existing challenges regarding the delivery of anticancer drugs but also extends the utility of current DOX-induced chemotherapy.

Intracellular Delivery of Doxorubicin by Iron Oxide-Based Nano-Constructs Increases Clonogenic Inactivation of Ionizing Radiation in HeLa Cells.

In this study, we determined the potential of polyethylene glycol-encapsulated iron oxide nanoparticles (IONPCO) for the intracellular delivery of the chemotherapeutic doxorubicin (IONPDOX) to enhance the cytotoxic effects of ionizing radiation. The biological effects of IONP and X-ray irradiation (50 kV and 6 MV) were determined in HeLa cells using the colony formation assay (CFA) and detection of γH2AX foci. Data are presented as mean ± SEM. IONP were efficiently internalized by HeLa cells. IONPCO radiomodulating effect was dependent on nanoparticle concentration and photon energy. IONPCO did not radiosensitize HeLa cells with 6 MV X-rays, yet moderately enhanced cellular radiosensitivity to 50 kV X-rays (DMFSF0.1 = 1.13 ± 0.05 (p = 0.01)). IONPDOX did enhance the cytotoxicity of 6 MV X-rays (DMFSF0.1 = 1.3 ± 0.1; p = 0.0005). IONP treatment significantly increased γH2AX foci induction without irradiation. Treatment of HeLa cells with IONPCO resulted in a radiosensitizing effect for low-energy X-rays, while exposure to IONPDOX induced radiosensitization compared to IONPCO in cells irradiated with 6 MV X-rays. The effect did not correlate with the induction of γH2AX foci. Given these results, IONP are promising candidates for the controlled delivery of DOX to enhance the cytotoxic effects of ionizing radiation.

Zinc oxide nanofluids: The influence of modality combinations on prostate cancer DU145 cells.

The combination of phototherapy and chemotherapy (chemophototherapy), presents a promising multimodal method for comprehensive cancer treatment. The aim of this study is to investigate the influence of low doses of zinc oxide (ZnO) nanofluids and ultraviolet A (UVA) irradiation on the cytotoxicity and cellular uptake of doxorubicin (DOX) on human prostate cancer DU145 cells. ZnO nanoparticles were prepared by the solvothermal method and 10% bovine serum albumin was used as the dispersant. The cytotoxic effect of DOX alone and in combination with different concentrations of ZnO nanofluids (0.95-15.6 μg/ml) in the presence and absence of UVA irradiation on DU145 cells was evaluated by -(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. DOX residue inside and outside of DU145 cells was explored by fluorescence microscopy and UV-Vis absorption spectroscopy, respectively. The role of ZnO nanofluids and UVA irradiation in DOX-induced apoptosis and cell cycle arrest were evaluated by DAPI staining, comet assay, and flow cytometry. The results revealed that low dose of ZnO nanofluids (0.95 μg/ml) accompanied with irradiation enhanced the cytotoxicity and intracellular delivery of DOX in DU145 cells. The percentage of chromatin fragmentation/condensation and DNA tail of DU145 cells treated simultaneously with DOX and ZnO nanofluids was increased after UVA irradiation, whereas no significant changes in cell cycle progression were observed. The results indicate that ZnO nanofluids in the presence of UVA irradiation could increase DOX efficiency in DU145 cells, suggesting such modality combinations as a promising approach in cancer treatment.

Dual Redox/pH-Sensitive Micelles Self-Assembled From Star-Like Amphiphilic Copolymers Based On Sucrose For Controlled Doxorubicin Delivery.

Novel dual redox/pH-sensitive star-like amphiphilic sucrose-oligo(butyl fumarate) (thioglycolic acid conjugate)-SS-poly(ethylene glycol) (Suc-OBF(TGA)-SS-PEG) copolymers and their self-assembled micelles were prepared and utilized for intracellular doxorubicin delivery. Importance of changing the hydrophobic chain length on micelles properties was investigated. Results showed that the micelles with longer hydrophobic chain exhibited smaller size and were more stable in aqueous solution. The redox and pH sensitivity of the micelles was confirmed by the change of micelle diameter/diameter distribution measured by dynamic light scattering and the change of micellar morphology observed by scanning electron microscope. The micelles display a decent doxorubicin loading capacity. Invitro release studies showed that only 14.3% doxorubicin was released from doxorubicin-loaded micelles under physiological conditions in 30h. The release of doxorubicin was accelerated at pH 5.5 or in the presence of 10mM glutathione at pH 7.4 (46.9% and 76.9% of doxorubicin was released, respectively, in 30h). The doxorubicin release was further expedited under pH 5.5 and 10mM GSH conditions (91.4%). Suc-OBF(TGA)-SS-PEG micelles displayed no cytotoxicity toward HDF cells. MTT assays indicated that doxorubicin-loaded micelles had good cytotoxicity against MCF-7cells. This work suggested that star-like amphiphilic Suc-OBF(TGA)-SS-PEG copolymer micelles may provide a promising platform for delivering doxorubicin and other hydrophobic anticancer drugs.

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.

Tumor microenvironment responsive nanogels as a smart triggered release platform for enhanced intracellular delivery of doxorubicin

The fabrication of novel and intelligent delivery systems that can effectively deliver therapeutics to the targeted site and release payload in enhanced/controlled manner is highly desired to overcome the multiple challenges in chemotherapy. The present article demonstrates the potential application of dual stimuli responsive nanogels as tumor microenvironment targeted drug delivery carrier. Disulfide cross-linked pH and redox responsive PEG-PDMAEMA nanogels were synthesized by atom transfer radical polymerization (ATRP). The nanogels were characterized by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The PEG-PDMAEMA nanogels exhibited dual stimuli-responsive release of the encapsulated model anticancer drug (doxorubicin, DOX) due to the acidic pH-response of dimethyl amine group in PDMAEMA and reductive cleavage of the disulfide linkages. A relatively higher release of DOX was observed from the nanogels at pH 5.0 than at pH 7.4. DOX release was further accelerated in tumor simulated environment of pH 5.0 and 10 mM glutathione (GSH). Confocal microscopy images revealed that DOX-loaded PEG-PDMAEMA nanogels can rapidly internalize and effectively deliver the drug into the cells. The nanogels exhibited higher cytotoxicity in GSH-OEt pretreated HeLa cells than untreated cells. The dual stimuli responsive nanogels synthesized in this study exhibited many favorable traits, such as pH and redox dependent controlled release of drug, biodegradability, biocompatibility, and enhanced cytotoxicity, which endow them as a promising candidate for anticancer drug delivery.

Efficient uptake and retention of iron oxide-based nanoparticles in HeLa cells leads to an effective intracellular delivery of doxorubicin

The purpose of this study was to construct and characterize iron oxide nanoparticles (IONPCO) for intracellular delivery of the anthracycline doxorubicin (DOX; IONPDOX) in order to induce tumor cell inactivation. More than 80% of the loaded drug was released from IONPDOX within 24 h (100% at 70 h). Efficient internalization of IONPDOX and IONPCO in HeLa cells occurred through pino- and endocytosis, with both IONP accumulating in a perinuclear pattern. IONPCO were biocompatible with maximum 27.9% ± 6.1% reduction in proliferation 96 h after treatment with up to 200 µg/mL IONPCO. Treatment with IONPDOX resulted in a concentration- and time-dependent decrease in cell proliferation (IC50 = 27.5 ± 12.0 μg/mL after 96 h) and a reduced clonogenic survival (surviving fraction, SF = 0.56 ± 0.14; versus IONPCO (SF = 1.07 ± 0.38)). Both IONP constructs were efficiently internalized and retained in the cells, and IONPDOX efficiently delivered DOX resulting in increased cell death vs IONPCO.

Calcium-mineralized polypeptide nanoparticle for intracellular drug delivery in osteosarcoma chemotherapy

The acidic microenvironments of tumor tissue and cells provide an opportunity for the development of pH-responsive drug delivery systems in cancer therapy. In this work, we designed a calcium carbonate (CaCO3)-core-crosslinked nanoparticle of methoxy poly(ethylene glycol)-block-poly(l-glutamic acid) through mineralization for intracellular delivery of doxorubicin (DOX), referred to as CaNP/DOX. CaNP/DOX exhibited high drug loading capability, uniform nanoparticle size, and pH-dependent DOX release. In the meantime, the enhanced cell uptake, superior cytotoxicity toward mouse osteosarcoma K7 cells, extended circulation half-life, and improved accumulation of DOX in K7 allograft tumor from CaNP/DOX were also demonstrated. More interestingly, CaNP/DOX displayed improved antitumor effect and reduced side effects against the K7 osteosarcoma-allografted mouse model and the 143B orthotopic osteosarcoma mouse model. Given the superior properties of Ca-mineralized polypeptide nanoparticle for intracellular drug delivery, the smart drug delivery system showed strong competitiveness in clinical chemotherapy of cancers.

Albumin nanoformulations as an innovative solution to overcome doxorubicin chemoresistance.

Aim: Resistance to chemotherapy is a major limiting factor that hamper the effectiveness of anticancer therapies. Doxorubicin is an antineoplastic agent used in the treatment of a wide range of cancers. However, it presents several limitations such as dose-dependent cardiotoxicity, lack of selectivity for tumor cells, and induced cell resistance. Nanotechnology represents a promising strategy to avoid these drawbacks. In this work, new albumin-based nanoparticles were formulated for the intracellular delivery of doxorubicin with the aim to overcome cancer drug resistance.Methods: Glycol chitosan-coated and uncoated albumin nanoparticles were prepared with a tuned coacervation method. The nanoformulations were in vitro characterized evaluating the physicochemical parameters, morphology, and in vitro release kinetics. Biological assays were performed on A2780res and EMT6 cells from human ovarian carcinoma and mouse mammary cell lines resistant for doxorubicin, respectively.Results: Cell viability assays showed that nanoparticles have higher cytotoxicity than the free drug. Moreover, at low concentrations, both doxorubicin-loaded nanoparticles inhibited the cell colony formation in a greater extent than drug solution. In addition, the cell uptake of the different formulations was investigated by confocal microscopy and by the HPLC determination of doxorubicin intracellular accumulation. The nanoparticles were rapidly internalized in greater extent compared to the free drug.Conclusion: Based on these results, doxorubicin-loaded albumin nanoparticles might represent a novel platform to overcome the mechanism of drug resistance in cancer cell lines and improve the drug efficacy.

Non-porous phosphonated ionic silica nanospheres as nanocarriers for efficient intracellular delivery of doxorubicin

A novel nanoscale drug delivery system based on monodispersed non-porous ionic silica nanospheres (NISNs) decorated with phosphonated active sides homogeneously distributed all over their surface, was developed. Doxorubicin (DOX), a well-known antitumor drug, was successfully loaded on the surface of the silica nanoparticles via electrostatic interactions. The final drug vehicle possesses excellent solubility, while enhancing significantly the efficacy of the drug. The administration of DOX-loaded NISNs against two aggressive DOX-resistant human prostate adenocarcinoma cell lines DU145 and PC3 leads to increased medicinal efficacy with extremely low DOX concentrations (0.1 μM) that could significantly reduce DOX side effects. In addition, NISNs was found to be non-toxic. The efficient cellular uptake of NISNs_DOX was confirmed by flow cytometry analysis and visualized by confocal microscopy. The translocation of DOX inside cells drastically changed, when DOX was bound to NISNs nanoparticles. Specifically, DOX loaded to NISNs nanoparticles is preferentially localized in the cytosol and significant efficacy was observed due to slow controlled release of DOX to the nucleus. The results reported in this work strongly support the potential utilization of NISNs derivatives as non-toxic nanocarriers for high loading efficiency and intracellular delivery of therapeutic drugs.

GSH and light dual stimuli-responsive supramolecular polymer drug carriers for cancer therapy

Glutathione (GSH)/light dual-responsive supramolecular drug carriers (abbreviated as CPAP) based on CD-PEG⊃Azo-PCL were fabricated for intracellular delivery of doxorubicin (DOX). The carriers were spherical with a diameter of 70–90 nm and exhibited GSH/light sensitivity. The GSH response attributed to disulfide bonds between PEG and β-cyclodextrin (β-CD), and the light response was achieved by a simple host-guest interaction between β-CD and azobenzene. DOX was encapsulated into the hydrophobic core of CPAP. The drug loaded CPAP (CPAP@DOX) displayed the fastest drug release in the presence of GSH and light simultaneously. The cytotoxicities of CPAP and CPAP@DOX were explored by SKOV3 cells and HEK293T cells. The results of cell experiments indicated that CPAP@DOX could effectively inhibit cancer cells while had reduced toxicity to normal cells. We believe that CPAP@DOX drug delivery system may present promising application for precisely controllable drug release.

Radiosensitization of Tumor Cells by Intracellular Delivery of Doxorubicin Using Novel Iron Oxide-based Nanoconstructs

Radiosensitization of Tumor Cells by Intracellular Delivery of Doxorubicin Using Novel Iron Oxide-based Nanoconstructs

A novel pH-sensitive polymeric prodrug was prepared by SPAAC click chemistry for intracellular delivery of doxorubicin and evaluation of its anti-cancer activity in vitro

A novel cytocompatible and pH-sensitive amphiphilic polymeric prodrug named as mPEG-b-norbornene functional PLA-graft-Doxorubicin (mPEG-b-PLA-g-DOX) was synthesized by ROP (ring-opening polymerization), then condensation and followed by click reaction. The polymeric carriers were grafted with triazo group. Doxorubicin (DOX) was modified by the cyclooctyne via condensation reaction and conjugated to the polymeric carriers through the SPAAC (Strain-Promoted Alkyne-Azide Cycloaddition) click reaction. There was a Schiff base between the DOX and cyclooctyne which could result in the pH stimuli-responsiveness for controlled release of anti-cancer drug. The resultant mPEG-b-PLA-g-DOX prodrug was characterized by the 1H NMR, GPC and HPLC. The content of DOX in prodrug reached 17.4% as measured by the UV spectrum. The amphiphilic polymeric prodrug could self-assemble into micelle which was characterized by the dynamic light scattering (DLS) and scanning electron microscope (SEM). The profile of in vitro drug release exhibited enhanced drug release at acidic pH (pH = 5.3) compared with neutral pH (pH = 7.4). The results of MTT assay showed that the amount of DOX required for MCF-7 cells was reduced after DOX molecules were prepared into polymer prodrug, which was conducive to reducing side effects under the premise of ensuring inhibitory effect.