Cisplatin-crosslinked glutathione-sensitive micelles loaded with doxorubicin for combination and targeted therapy of tumors

Tailor-Made Polysaccharides for Biomedical Applications

Polysaccharides (PSAs) are carbohydrate-based macromolecules widely used in the biomedical field, either in their pure form or in blends/nanocomposites with other materials. The relationship between structure, properties, and functions has inspired scientists to design multifunctional PSAs for various biomedical applications by incorporating unique molecular structures and targeted bulk properties. Multiple strategies, such as conjugation, grafting, cross-linking, and functionalization, have been explored to control their mechanical properties, electrical conductivity, hydrophilicity, degradability, rheological features, and stimuli-responsiveness. For instance, custom-made PSAs are known for their worldwide biomedical applications in tissue engineering, drug/gene delivery, and regenerative medicine. Furthermore, the remarkable advancements in supramolecular engineering and chemistry have paved the way for mission-oriented biomaterial synthesis and the fabrication of customized biomaterials. These materials can synergistically combine the benefits of biology and chemistry to tackle important biomedical questions. Herein, we categorize and summarize PSAs based on their synthesis methods, and explore the main strategies used to customize their chemical structures. We then highlight various properties of PSAs using practical examples. Lastly, we thoroughly describe the biomedical applications of tailor-made PSAs, along with their current existing challenges and potential future directions.

Doxorubicin-loaded micelles in tumor cell-specific chemotherapy

Nanomedicine is a field that combines biology and engineering to improve disease treatment, particularly in cancer therapy. One of the promising techniques utilized in this area is the use of micelles, which are nanoscale delivery systems that are known for their simple preparation, high biocompatibility, small particle size, and the ability to be functionalized. A commonly employed chemotherapy drug, Doxorubicin (DOX), is an effective inhibitor of topoisomerase II that prevents DNA replication in cancer cells. However, its efficacy is frequently limited by resistance resulting from various factors, including increased activity of drug efflux transporters, heightened oncogenic factors, and lack of targeted delivery. This review aims to highlight the potential of micelles as new nanocarriers for delivering DOX and to examine the challenges involved with employing chemotherapy to treat cancer. Micelles that respond to changes in pH, redox, and light are known as stimuli-responsive micelles, which can improve the targeted delivery of DOX and its cytotoxicity by facilitating its uptake in tumor cells. Additionally, micelles can be utilized to administer a combination of DOX and other drugs and genes to overcome drug resistance mechanisms and improve tumor suppression. Furthermore, micelles can be used in phototherapy, both photodynamic and photothermal, to promote cell death and increase DOX sensitivity in human cancers. Finally, the alteration of micelle surfaces with ligands can further enhance their targeted delivery for cancer suppression.

Reduction-responsive dextran-based Pt(IV) nano-prodrug showed a synergistic effect with doxorubicin for effective melanoma treatment

Melanoma, the deadliest skin cancer with high metastasis potential, has posed a great threat to human health. Accordingly, early efficient blocking of melanoma progression is vital in antitumor treatment. Herein, a reduction-responsive dextran-based Pt(IV) nano-prodrug (PDPN) was synthesized and used for doxorubicin (DOX) delivery to combat melanoma synergistically. First, PDPN was prepared by one-pot chemical coupling of carboxylated methoxy poly(ethylene glycol) (mPEG), dextran (Dex), and the crosslinking agent cisPt (IV)-COOH. PDPN had a spherical structure (R_h = 34 ± 11.3 nm). Then, DOX was encapsulated into the PDPN core to form DOX-loaded PDPN (PDPN-DOX). The obtained PDPN-DOX displayed reduction-responsive release of DOX and Pt, thus showing a synergistic anticancer effect in B16F10 cells (combination index, 0.46). Furthermore, in vivo experiments demonstrated that PDPN-DOX was effective for the synergistic treatment of subcutaneous melanoma. Collectively, the as-prepared PDPN could serve as a promising and versatile nano-prodrug carrier for the co-delivery of chemotherapeutics in tumor combination therapy.

Biosynthetic Luminescent Ag Nanoparticles in Functionalization for Breast Cancer Therapy

Breast cancer is still the most common malignant tumor in the world despite the research and technique advances. However, how to come true targeted controlled release perplexing the clinicians all the time and rapid development of nanotechnology, as well as emerging microRNA (miRNA), offers an opportunity for diagnosis and treatment of breast cancer. Here, nude mouse model with breast cancer was built and silver nanoparticles (Ag-NPs, ANPs) with near infrared characteristic were biosynthesized. Then, RNA-seq, western blot analysis, and immunofluorescence of the differential expression spectrum of cultured mouse T cells treated by silver nitrate in vitro hinted that biosynthesis of ANPs in cells depended on participation of ferritin and serum albumin (SA). Subsequently, ANPs loaded with miR-200c (miR-200c@ANPs) in vivo and in vitro showed its well property of intelligent controlled release, function of targeted imaging, and potential targeted therapy. The present data indicated that biosynthesized miR-200c@ANPs was equipped with biocompatibility, intelligent controlled release drug, tumor targeting therapy, as well as the visual function. More, this method may be a promising alternative option for diagnosis and treatment of breast cancer.

Co-delivery of gemcitabine and cisplatin via Poly (L-glutamic acid)-g-methoxy poly (ethylene glycol) micelle to improve the in vivo stability and antitumor effect

PURPOSE

The intention of the study was to co-delivery gemcitabine and cisplatin with totally different nature by prodrug and micelle strategy to improve its in vivo stability and antitumor effect.

METHODS

A prodrug of gemcitabine (mPEG-PLG-GEM) was synthesized through the covalent conjugation between the primary amino group of gemcitabine and the carboxylic group of poly (L-glutamic acid)-g-methoxy poly (ethylene glycol) (mPEG-PLG). It was prepared into micelles by a solvent diffusion method, and then combined with cisplatin through chelation to prepare gemcitabine and cisplatin co-loaded mPEG-PLG micelles (mPEG-PLG-GEM@CDDP micelles).

RESULTS

Gemcitabine and cisplatin in each micelle group were released more slowly than in solutions. In addition, pharmacokinetics behaviors of them were improved after encapsulated in prodrug micelles. T_1/2z of gemcitabine and cisplatin encapsulated in micelles were prolonged to 6.357 h (mPEG-PLG-GEM), 10.490 h (mPEG-PLG@CDDP), 5.463 h and 12.540 h (mPEG-PLG-GEM@CDDP) compared with GEM@CDDP solutions (T_1/2z = 1.445 h and 7.740 h). The ratio of synergy between gemcitabine and cisplatin (3:1 ~ 1:1(n/n)) was guaranteed in the systemic circulation, thus improving its antitumor effect. The results of biochemical analysis showed that GEM@CDDP-Sol was more toxic to kidneys and marrow compared with mPEG-PLG-GEM@CDDP micelles.

CONCLUSIONS

By prodrug strategy, gemcitabine and cisplatin with totally different nature were prepared into micelles and obtained a better pharmacokinetic behavior. And the dual drug delivery system performed a better in vivo stability and antitumor effect compared with each single drug delivery system in the experiment. Scheme. Schematic of mPEG-PLG-GEM@CDDP micelles' formation and action process.

Nanobodies as versatile tools: A focus on targeted tumor therapy, tumor imaging and diagnostics

Monoclonal antibodies and vaccines have widely been studied for the immunotherapy of cancer, though their large size appears to limit their functionality in solid tumors, in large part due to unique properties of tumor microenvironment. Smaller formats of antibodies have been developed to throw such restrictions. These small format antibodies include antigen binding fragments, single-chain variable fragments, single variable domain of camelid antibody (so-called nanobody (Nb) or VHH). Since their serendipitous discovery, nanobodies have been studies at length in the fields of research, diagnostics and therapy. These antigen binding fragments, originating from camelid heavy-chain antibodies, possess unusual hallmarks in terms of (small) size, stability, solubility and specificity, hence allowing cost-effective production and sometimes out performing monoclonal antibodies. In addition, these small camelid heavy-chain antibodies are highly adaptable tools for cancer research as they enable specific modulation of targets, enzymatic and non-enzymatic proteins alike. Molecular imaging studies benefit from the rapid, homogeneous tumor accumulation of nanobodies and their fast blood clearance, permitting previously unattainable fast tumor visualization. Moreover, they are endowed with considerable therapeutic potential as inhibitors of receptor-ligand pairs and deliverers of drugs or drug-loaded nanoparticles towards tumors. In this review, we shed light on the current status of nanobodies in diagnosis and imaging of tumor and exploiting nanobodies revert immunosuppressive events, modulation of immune checkpoints, and as deliverers of drugs for targeted tumor therapy.

Glycyrrhetinic acid remodels the tumor microenvironment and synergizes with doxorubicin for breast cancer treatment in a murine model

We aimed to combine glycyrrhetinic acid with doxorubicin to prepare, characterize and evaluate a drug delivery nano-system with REDOX sensitivity for the treatment of breast cancer. M-DOX-GA NPs prepared by nano sedimentation were spherical, with a particle size of 181 nm. And the maximum encapsulation efficiency and drug loading in M-DOX-GA NPs were 89.28% and 18.22%, respectively. Cytotoxicity and cellular uptake experiments of nanoparticles to KC cells, Cal-27 cells and 4T1 cells were studied by the CCK-8 method. The result indicated that M-DOX-GA NPs could accurately release the drug into the tumor cells, thus achieving the targeted release of the drug. Comparing the survival rate of the above three cells, it was found that M-DOX-GA NPs had a good tumor selectivity and had a more significant therapeutic effect on breast cancer. A 4T1-bearing mouse model was established, and the tumor inhibition rate was 77.37% after injection of nanoparticle solution for 14 d. Normal tissue H&E stained sections and TUNEL assay were verified M-DOX-GA NPs have excellent tumor suppressive effect, and can efficiently reduce the toxic side effects on normal organisms, and effectively avoided 4T1 cells metastasis. Immunofluorescence detection and Western-blot analysis figured a decline in both CUGBP1 and α-SMA, which verifying the TME remodeling induced by glycyrrhetinic acid. Collectively, the combination of doxorubicin and glycyrrhetinic acid is an effective and safe strategy for remodeling fibrotic TME by improving the therapeutic outcome for breast cancer.

The Therapeutic Efficacy of Dendrimer and Micelle Formulations for Breast Cancer Treatment

Breast cancer is among the most common types of cancer in women and it is the cause of a high rate of mortality globally. The use of anticancer drugs is the standard treatment approach used for this type of cancer. However, most of these drugs are limited by multi-drug resistance, drug toxicity, poor drug bioavailability, low water solubility, poor pharmacokinetics, etc. To overcome multi-drug resistance, combinations of two or more anticancer drugs are used. However, the combination of two or more anticancer drugs produce toxic side effects. Micelles and dendrimers are promising drug delivery systems that can overcome the limitations associated with the currently used anticancer drugs. They have the capability to overcome drug resistance, reduce drug toxicity, improve the drug solubility and bioavailability. Different classes of anticancer drugs have been loaded into micelles and dendrimers, resulting in targeted drug delivery, sustained drug release mechanism, increased cellular uptake, reduced toxic side effects of the loaded drugs with enhanced anticancer activity in vitro and in vivo. This review article reports the biological outcomes of dendrimers and micelles loaded with different known anticancer agents on breast cancer in vitro and in vivo.

ROP and ATRP fabricated redox sensitive micelles based on PCL-SS-PMAA diblock copolymers to co-deliver PTX and CDDP for lung cancer therapy

Combining dual drugs in one vehicle to cancer cells offers spatiotemporal localization of drug at the site of action, leading to synergistic therapeutic effects and reduced side effects. To improve pH/redox responsiveness to the tumor microenvironments for cancer therapy, a pH/redox-responsive micelle based on poly(ε-caprolactone)-SS-poly(methacrylic acid) (PCL-SS-PMAA) diblock copolymer was fabricated for dual drug delivery. The PCL-SS-PMAA was formulated into a core-shell micelle (PSPm) in an aqueous solution. The critical micelle concentration (CMC) values of PSPm were 7.94 × 10^-3 mg mL^-1 at pH 5.0 and 1.00 × 10^-2 mg mL^-1 at pH 7.4. The hydrodynamic diameters of PSPm were within 210-270 nm, depending on pH values. Changes in morphology and size of PSPm were clearly observed before and after exposure to a reducing agent. Paclitaxel (PTX) was encapsulated into the core and cisplatin (CDDP) was chelated on the shell of PSPm, with both PTX and CDDP being efficiently released from PSPm in the presence of a reducing agent in an acid condition. MTT and annexin V/propidium iodide dual staining results demonstrated that co-loading of CDDP and PTX into PSPm had a synergistic effect in killing lung cancer cells and exerted superior antitumor activity over the combination of single drug-loaded PSPm or the combination of free-CDDP and free-PTX at equivalent drug amounts. Hence, encapsulating the dual drugs into PSPm exhibits a synergistic effect for potential lung cancer therapy.

Combination Therapy with Doxorubicin-Loaded Reduced Albumin Nanoparticles and Focused Ultrasound in Mouse Breast Cancer Xenografts

Because chemotherapeutic drugs are often associated with serious side effects, the central topic in modern drug delivery is maximizing the localization of drugs at the target while minimizing non-specific drug interactions at unwanted regions. To address this issue, biocompatible nanoparticles have been developed to enhance the drug half-life while minimizing the associated toxicity. Nevertheless, relying solely on the enhanced half-life and enhanced permeability and retention (EPR) effects has been ineffective, and designing stimulus-sensitive nanoparticles to introduce the precise control of drug release has been desired. In this paper, we introduce a pH-sensitive, reduced albumin nanoparticle in combination with focused ultrasound treatment. Not only did these nanoparticles have superior therapeutic efficacy and toxicity profiles when compared to the free drugs in xenograft mouse models, but we were also able to show that the albumin nanoparticles reported in this paper were more suitable than other types of non-reduced albumin nanoparticles as vehicles for drug delivery. As such, we believe that the albumin nanoparticles presented in this paper with desirable characteristics including the induction of strong anti-tumor response, precise control, and superior safety profiles hold strong potential for preclinical and clinical anticancer therapy.

Structure and Properties of Oxidized Chitosan Grafted Cashmere Fiber by Amide Covalent Modification

In this study, oxidized chitosan grafted cashmere fibers (OCGCFs) were obtained by crosslinking the oxidized chitosan onto cashmere fibers by amide covalent modification. A novel method was developed for the selective oxidation of the C6 primary hydroxyls into carboxyl groups for chitosan. The effect of oxidization reaction parameters of HNO₃/H₃PO₄-NaNO₂ mediated oxidation system on the oxidation degree, structure, and properties of chitosan were investigated. The chemical structure of the oxidized chitosan was characterized by solid-state cross-polarization magic angle spinning carbon-13 Nuclear Magnetic Resonance (CP/MAS ¹³C-NMR), Fourier transform infrared spectroscopy (FT-IR), and its morphology was investigated by scanning electron microscopy (SEM). Subsequently, the effect of the oxidized chitosan grafting on OCGCF was examined, and the physical properties, moisture regain, and antibacterial activity of OCGCFs were also evaluated. The results showed that oxidation of chitosan mostly occurred at the C6 primary hydroxyl groups. Moreover, an oxidized chitosan with 43.5-56.8% carboxyl content was realized by ranging the oxidation time from 30 to 180 min. The resulting OCGCF had a C-N amido bond, formed as a result of the reaction between the primary amines in the cashmere fibers and the carboxyl groups in the oxidized chitosan through the amide reaction. The OCGCF exhibited good moisture regain and remarkable bacteriostasis against both Staphylococcus aureus and Escherichia coli bacteria with its durability.

PEGylated nano-graphene oxide as a nanocarrier for delivering mixed anticancer drugs to improve anticancer activity

Due to their high specific surface area, graphene oxide and graphene oxide-base nanoparticles have great potential both in dual-drug delivery and combination chemotherapy. Herein, we developed cisplatin (Pt) and doxorubicin (DOX) dual-drug-loaded PEGylated nano-graphene oxide (pGO) to facilitate combined chemotherapy in one system. In this study, nano-sized pGO-Pt/DOX ranged around 161.50 nm was fabricated and characterized using zeta-potential, AFM, TEM, Raman, UV-Vis, and FTIR analyses. The drug delivery efficacy of Pt was enhanced through the introduction of pGO, and the final weight ratio of DOX: Pt: pGO was optimized to 0.376: 0.376: 1. In vitro studies revealed that pGO-Pt/DOX nanoparticles could be effectively delivered into tumor cells, in which they induced prominent cell apoptosis and necrosis and exhibited higher growth inhibition than the single drug delivery system or free drugs. The pGO-Pt/DOX induced the most prominent cancer cell apoptosis and necrosis rate with 18.6%, which was observed almost 2 times higher than that of pGO-Pt or pGO-DOX groups. in the apoptosis and necrotic quadrants In vivo data confirmed that the pGO-Pt/DOX dual-drug delivery system attenuated the toxicity of Pt and DOX to normal organs compared to free drugs. The tumor inhibition data, histopathology observations, and immunohistochemical staining confirmed that the dual-drug delivery system presented a better anticancer effect than free drugs. These results clearly indicated that the pGO-Pt/DOX dual-drug delivery system provided the means for combination drug delivery in cancer treatment.

Collaborative assembly of doxorubicin and galactosyl diblock glycopolymers for targeted drug delivery of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) patients suffer from severe pain due to the serious systemic side effects and low efficiency of chemotherapeutic drugs, and it is important to develop novel drug delivery systems to circumvent these issues. In this study, a series of galactose-based glycopolymers, poly(N-(prop-2-enoyl)-β-d-galactopyranosylamine)-b-poly(N-isopropyl acrylamide) (pGal(OH)-b-pNIPAA), were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and tetrabutylammonium hydroxide (TBAOH)-mediated removal of acetyl groups. Hydrophilic doxorubicin hydrochloride was introduced to undergo collaborative assembly with poly(N-(prop-2-enoyl)-β-d-peracetylated galactosamine)-b-poly(N-isopropyl acrylamide) (pGal(Ac)-b-pNIPAA) via TBAOH treatment. pGal-b-pNIPAA/doxorubicin (DOX) delivery nanoparticles (GND NPs) formed by collaborative assembly were fully characterized by NMR, TEM and FT-IR, indicating the well-controlled formation of particles with uniform size and high efficiency in terms of drug loading and encapsulation compared with conventional adsorption methods. Meanwhile, the GND NPs were observed to be rapidly disintegrated under acidic conditions and resulted in an increased release of DOX. Cellular experiments showed that pGal-b-pNIPAA/DOX is apparently an asialoglycoprotein receptor (ASGPR)-mediated target of HCC, resulting in enhanced cellular uptake to HepG2 cells and anti-tumor efficacy in vitro. Furthermore, GND NPs III exerted more sustainable and effective anti-tumor effects compared to free DOX on a transgenic zebrafish TO(Kras^G12V) model in vivo. These results indicated that the biocompatible nanomaterials developed by collaborative assembly with galactosyl diblock glycopolymers and DOX may serve as a promising candidates for targeting therapy of HCC.

Co-delivery of cisplatin and doxorubicin by covalently conjugating with polyamidoamine dendrimer for enhanced synergistic cancer therapy

Because of the synergistic effects of drugs and minimal drug dose for cancer therapy, combination chemotherapy is frequently used in the clinic. In this study, hyaluronic acid-modified amine-terminated fourth-generation polyamidoamine dendrimer nanoparticles were synthesized for systemic co-delivery of cisplatin and doxorubicin (HA@PAMAM-Pt-Dox). In vitro data showed that HA@PAMAM-Pt-Dox can enter the cells through the lysosome mediated-pathway in a time-dependent manner. Cell viability studies indicated that HA@PAMAM-Pt-Dox exhibited a higher anticancer activity on MCF-7 and MDA-MB-231 breast cancer cells at a relative low concentration. HA@PAMAM-Pt-Dox not only efficiently inhibited tumor growth but also significantly reduced the toxicity of Dox. Moreover, intravenous administration of HA@PAMAM-Pt-Dox to MDA-MB-231 tumor-bearing BALB/c nude mice resulted in the accumulation of HA@PAMAM-Pt-Dox at the tumor site, thereby significantly inhibiting tumor growth without apparent toxicity. These results suggested that HA@PAMAM-Pt-Dox has great potential to improve the chemotherapeutic efficacy of cisplatin and doxorubicin in breast cancer. STATEMENT OF SIGNIFICANCE: One of the main problems in cancer treatment is the development of drug resistance. To date, it is believed that combination chemotherapy might be an effective strategy for the above problem. However, for two completely different drugs, combination chemotherapy faces huge difficulties including the antagonistic nature of drugs, variations in drugs in terms of solubility, and limited tumor targeting. Recent developments in nanoscience and nanotechnology provide an effective approach for such disadvantages. Considering the advantages of dendrimers such as control of size and molecular weight, bioavailability, and biosafety, we used fourth-generation dendrimers modified by HA as drug vectors by covalently conjugating them with anticancer drugs (cisplatin and doxorubicin) to form a nanodrug delivery system, named HA@PAMAM-Pt-Dox. We observed that the HA@PAMAM-Pt-Dox system can effectively kill breast cancer cells both in vitro and in vivo, which showed a favorable synergistic effect. This strategy can be extended to other drugs, thus providing a highly effective strategy for cancer treatment.

Redox-responsive biocompatible nanocarriers based on novel heparosan polysaccharides for intracellular anticancer drug delivery

Heparosan is a natural precursor of heparin biosynthesis in mammals. It is stable in blood circulation but can be degraded in lysosomes, showing good biocompatibility and long circulation features. So heparosan can be designed as anticancer drug carriers to increase tumor selectivity and improve the therapeutic effect. A novel redox-sensitive heparosan-cystamine-vitamin E succinate (KSV) micelle system was constructed for intracellular delivery of doxorubicin (DOX). Simultaneously, the redox-insensitive heparosan-adipic acid dihydrazide-vitamin E succinate copolymer (KV) was synthesized as control. DOX-loaded micelles (DOX/KSV) with an average particle size of 90–120 nm had good serum stability and redox-triggered depolymerization. In vitro drug release test showed that DOX/KSV micelles presented obvious redox-triggered release behavior compared with DOX/KV. Cytotoxicity and cell uptake were investigated using MGC80-3 tumor cells and COS7 fibroblast-like cells. The cell survival rate of blank micelles was more than 90%, and the cytotoxicity of DOX/KSV in MGC80-3 cells was higher than in COS7 cells, indicating that the carrier has better biocompatibility and less toxicity side effect. The cytotoxicity of DOX/KSV against MGC80-3 cells was significantly greater than that of free DOX and DOX/KV. Furthermore, compared with DOX/KV in MGC80-3 cells, DOX/KSV micelles uptook more anticancer drugs and then released DOX faster into the cell nucleus. The micelles were endocytosed by multiple pathways, but clathrin-mediated endocytosis was the main pathway. Therefore, heparosan polysaccharide could be a potential option as anticancer carrier for enhancing efficacy and mitigating toxicity.

A facile strategy for fine-tuning the stability and drug release of stimuli-responsive cross-linked micellar nanoparticles towards precision drug delivery

Precision drug delivery has a great impact on the application of precision oncology for better patient care. Here we report a facile strategy for fine-tuning the stability, drug release and responsiveness of stimuli-responsive cross-linked nanoparticles towards precision drug delivery. A series of micellar nanoparticles with different levels of intramicellar disulfide crosslinkages could be conveniently produced with a mixed micelle approach. These micellar nanoparticles were all within a size range of 25-40 nm so that they could take full advantage of the enhanced permeability and retention (EPR) effect for tumor-targeted drug delivery. The properties of these nanoparticles such as critical micelle concentration (CMC), stability, drug release and responsiveness to a reductive environment could be well correlated with the levels of crosslinking (LOC). Compared to the micellar nanoparticles with a LOC at 0% that caused the death of animals of two species (mouse and rat) due to the acute toxicity such as hemolysis, the nanoparticles at all other levels of crosslinking were much safer to be administered into animals. The in vitro antitumor efficacy of micellar nanoparticles crosslinked at lower levels (20% & 50%) were much more effective than that of 100% crosslinked micellar nanoparticles in SKOV-3 ovarian cancer cells.

Synthesis and antiproliferative activities of doxorubicin thiol conjugates and doxorubicin-SS-cyclic peptide

Myocardial toxicity and drug resistance caused by drug efflux are major limitations of doxorubicin (Dox)-based chemotherapy. Dox structure modification could be used to develop conjugates with an improved biological profile, such as antiproliferative activity and higher cellular retention. Thus, Dox thiol conjugates, Dox thiol (Dox-SH), thiol-reactive Dox-SS-pyridine (SS = disulfide), and a Dox-SS-cell-penetrating cyclic peptide, Dox-SS-[C(WR)₄K], were synthesized. Dox was reacted with Traut's reagent to generate Dox-SH. The thiol group was activated by the reaction with dithiodipyridine to afford the corresponding Dox-SS-Pyridine (Dox-SS-Pyr). A cyclic cell-penetrating peptide containing a cysteine residue [C(WR)₄K] was prepared using Fmoc solid-phase strategy. Dox-SS-Py was reacted with the free sulfhydryl of cysteine in [C(WR)₄K] to generate Dox-SS-[C(WR)₄K] as a Dox-cyclic peptide conjugate. Cytotoxicity of the compounds was examined in human embryonic kidney (HEK-293), human ovarian cancer (SKOV-3), human fibrosarcoma (HT-1080), and human leukemia (CCRF-CEM) cells. Dox-SH and Dox-SS-pyridine were found to have significantly higher or comparable cytotoxicity when compared to Dox in HEK-293, HT-1080, and CCRF-CEM cells after 24 h and 72 incubation, presumably because of higher activity and retention of the compounds in these cells. Furthermore, Dox-SS-[C(WR)₄K] showed significantly higher cytotoxic activity in HEK-293, HT-1080, and SKOV-3 cells when compared with Dox after 72 h incubation. Dox-SS-Pyr exhibited higher cellular uptake than Dox-SS-[C(WR)₄K] in HT-1080 and HEK-293 cells as shown by flow cytometry. Fluorescence microscopy exhibited that Dox-SS-Pyr, Dox-SH, and Dox-SS-[C(WR)₄K] localized in the nucleus as shown in four cell lines, HT-1080, SKOV-3, MDA-MB-468, and MCF-7. Of note, Dox-SS-[C(WR)₄K] was significantly less toxic in mouse myoblast cells compared to Dox at the same concentration. Further mechanistic study demonstrated that the level of intracellular reactive oxygen species (ROS) in myoblast cells exposed to Dox-SS-[C(WR)₄K] was reduced in comparison of Dox when co-treated with FeCl₂. These data indicate that Dox-SH, Dox-SS-Pyr, and Dox-SS-[C(WR)₄K] have the potential to be further examined as Dox alternatives and anticancer agents.

Vitamin E-based redox-sensitive salinomycin prodrug-nanosystem with paclitaxel loaded for cancer targeted and combined chemotherapy

Cancer stem cells (CSCs) can resist conventional chemotherapy to lead to cancer recurrence. For complete eradication of cancers, an effective CSCs therapeutic strategy should be developed to combine with conventional chemotherapy. In this work, a novel vitamin E-based redox-sensitive salinomycin (SAL, an inhibitor for CSCs) prodrug nanoparticles (TS NPs) and hyaluronic acid (HA)-coated TS NPs (HTS NPs) were fabricated to deliver paclitaxel (PTX) for cancer-targeted and combined chemotherapy. Both TS and HTS prodrug NPs had mean diameter of about 200 nm with uniform size distribution, excellent drug loading capacity for PTX, and glutathione-triggered SAL and PTX release profiles. The HTS prodrug NPs had enhanced cellular uptake efficiency over TS NPs due to CD44 receptor-mediated endocytosis, hence exerting stronger potency of SAL upon CSCs-enriched mammospheres formation and G₀/G₁ cell phase arresting. Cytotoxicity and 3D tumor spheroids assays demonstrated that both TS and HTS prodrug NPs themself can synergize with loaded PTX to maximize the chemotherapeutic effect. Obviously, the latter demonstrated a more potent anticancer efficacy due to improved intracellular drug delivery efficiency. These results suggested that the designed TS prodrug NPs, especially the coated HTS NPs can serve as an effective anti-CSCs strategy for cancer targeted and combination treatments.

Bone-targeting nanoparticle to co-deliver decitabine and arsenic trioxide for effective therapy of myelodysplastic syndrome with low systemic toxicity

Myelodysplastic syndromes (MDS) are a diverse group of bone marrow disorders and clonal hematopoietic stem cell disorders characterized by abnormal blood cells, or reduced peripheral blood cell count. Recent clinical studies on combination therapy of decitabine (DAC) and arsenic trioxide (ATO) have demonstrated synergy on MDS treatment, but the treatment can cause significant side effects to patients. In addition, both drugs have to be administered on a daily basis due to their short half-lives. In addressing key issues of reducing toxic side effects and improving pharmacokinetic profiles of the therapeutic agents, we have developed a new formulation by co-packaging DAC and ATO into alendronate-conjugated bone-targeting nanoparticles (BTNPs). Our pharmacokinetic studies revealed that intravenously administered BTNPs increased circulation time up to 3days. Biodistribution analysis showed that the BTNP facilitated DAC and ATO accumulation in the bone, which is 6.7 and 7.9 times more than untargeted NP. Finally, MDS mouse model treated with BTNPs showed better restoration of complete blood count to normal level, and significantly longer median survival as compared to free drugs or untargeted NPs treatment. Our results support bone-targeted co-delivery of DAC and ATO for effective treatment of MDS.

Chitosan based nanogels stepwise response to intracellular delivery kinetics for enhanced delivery of doxorubicin

Chitosan based nanogels with pH/redox sensitivities tunable to stepwise response to intracellular delivery kinetics were developed. The nanogels were simply constructed by ionic gelation first, between O-Carboxymethyl-chitosan (CMCS) and thiolated chitosan (TCS), and then oxidation to form disulfide bonds for CMCS-TCS nanogels (CTNGs). Doxorubicin loaded nanogels (DOX/CTNGs) exhibited desirable stability under physiological pH with a mean size of 150.5nm, and quickly aggregated at pH 5.5 (mimic endo/lysosomes) due to protonation of the carboxyl groups on CMCS. DOX/CTNGs would maintain their TCS skeleton in acidic pH and compromised as treated with 10mM glutathione (mimic cytosol). In agreement with the structural variation, release of DOX was dramatically enhanced by the synergetic effects of acidic pH and reductive potential. Stepwise responses to intracellular delivery kinetics were evidenced by laser confocal images showing that DOX/CTNGs underwent efficient cellular internalization through endocytosis, endo/lysomse escape via self-precipitation, cleavage of disulfide linkage in cytosol and disintegration in nucleus, achieving enhanced nuclear delivery and rapid release of doxorubicin. DOX/CTNGs exerted comparable or higher anticancer efficacies than that of free DOX against hela cells. The simple construction of the nanogels and their capacity of enhancing anticancer activities of DOX are potential for translational applications in cancer chemotherapy.

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.

Comparison in docetaxel-loaded nanoparticles based on three different carboxymethyl chitosans

In this study, three different carboxymethyl chitosans (CMCs), namely O-carboxymethyl chitosan (OC), N-carboxymethyl chitosan (NC) and N,O-carboxymethyl chitosan (NOC), were prepared as nano-carriers for an anti-tumor drug, docetaxel (DCT). Three CMCs were fabricated into drug-loading nanoparticles under different preparing conditions respectively. A series of characterization parameters were determined including drug loading capacity (DC), entrapment efficiency (EE), particle size distribution, zeta potential, and morphology, which were used to find the optimized preparing condition for three kinds of nanoparticles (NPs). Furthermore, the in vitro drug release profiles of all the three kinds of nanoparticles showed a sustained release behavior and the release rate of OC-NPs was the fastest. Moreover, compared with NC-NPs and NOC-NPs, OC-NPs exhibited more cellular accumulation in the human gastric carcinoma cells (SGC 7901) as quantitatively determined by the flow cytometry and also much stronger cytotoxicity against these cells. Accordingly, our results showed that drug-loaded nanoparticles formed by different CMCs have dissimilar physiochemical characteristics which subsequently influence their therapeutic effects. We suggest that OC-based nanoparticle is a more desirable anti-tumor drug delivery system than NC-NP and NOC-NP.

Simply constructed chitosan nanocarriers with precise spatiotemporal control for efficient intracellular drug delivery

A novel intelligent nanocarrier with pH and redox sensitivities was developed based on Carboxymethyl-chitosan (CMCS) and thioglycolic acid conjugated chitosan (TCS) to provide precise spatiotemporal control for efficient intracellular delivery. Doxorubicin (DOX) loaded nanocarriers (DOX/CMCS-TCS NPs) were simply prepared by ionic gelation and then oxidation crosslink. The nanocarriers exhibited decent stability at pH 7.4 for up to 3days and underwent aggregation under acidic pH (5.5) due to protonation of the carboxyl groups on CMCS. The TCS skeleton was stable at pH 5.5 (mimic endo/lysosomes) but disintegrated in the presence of 10mM glutathione (GSH) at pH 7.4 (mimic cytosol). In vitro DOX release from DOX/CMCS-TCS NPs was enhanced at pH 5.5 compared with physiological condition, with 64.2% and 31.6% DOX released in 2h, respectively. While 85.2% of DOX was released within 2h as treated with 10mM GSH, suggesting the release was closely associated with structural disintegration of nanocarriers. The maximum release of DOX was obtained at 10mM GSH and pH 5.5 with 92.3% of DOX released in 5h. Confocal laser scanning microscopy observation indicated that DOX/CMCS-TCS NPs efficiently escaped from endo/lysosomes within 1h incubation with MCF-7 cells and gave the best performance in delivering DOX into nucleus in 2h. Anticancer activity assay revealed that DOX/CMCS-TCS NPs had comparable or even better inhibition of cell viability at high drug concentrations than free DOX, with the IC₅₀ of 0.6μg/mL following 48h incubation. In summary, the simply constructed DOX/CMCS-TCS NPs could not only respond to intracellular delivery temporally, they also achieve rapid release spatially in nucleus, which provide a precise spatiotemporal control of drug delivery for cancer therapy.