Electrostatic charge conversion processes in engineered tumor-identifying polypeptides for targeted chemotherapy

Solid-Phase Synthesized Copolymers for the Assembly of pH-Sensitive Micelles Suitable for Drug Delivery Applications

Diblock copolymers of polyhistidine are known for their self-assembly into micelles and their pH-dependent disassembly due to the amphiphilic character of the copolymer and the unsaturated imidazole groups that undergo a hydrophobic-to-hydrophilic transition in an acidic pH. This property has been largely utilized for the design of drug delivery systems that target a tumor environment possessing a slightly lower extracellular pH (6.8–7.2). The main purpose of this study was to investigate the possibility of designed poly(ethylene glycol)-polyhistidine sequences synthesized using solid-phase peptide synthesis (SPPS), to self-assemble into micelles, to assess the ability of the corresponding micelles to be loaded with doxorubicin (DOX), and to investigate the drug release profile at pH values similar to a malignant extracellular environment. The designed and assembled free and DOX-loaded micelles were characterized from a physico-chemical point of view, their cytotoxicity was evaluated on a human breast cancer cell line (MDA-MB-231), while the cellular areas where micelles disassembled and released DOX were assessed using immunofluorescence. We concluded that the utilization of SPPS for the synthesis of the polyhistidine diblock copolymers yielded sequences that behaved similarly to the copolymeric sequences synthesized using ring-opening polymerization, while the advantages of SPPS may offer facile tuning of the histidine site or the attachment of a large variety of functional molecules.

Hypoxia-Responsive Azobenzene-Linked Hyaluronate Dot Particles for Photodynamic Tumor Therapy

In this study, we developed ultra-small hyaluronate dot particles that selectively release phototoxic drugs into a hypoxic tumor microenvironment. Here, the water-soluble hyaluronate dot (dHA) was covalently conjugated with 4,4′-azodianiline (Azo, as a hypoxia-sensitive linker) and Ce6 (as a photodynamic antitumor agent), producing dHA particles with cleavable Azo bond and Ce6 (dHA-Azo-Ce6). Importantly, the inactive Ce6 (self-quenched state) in the dHA-Azo-Ce6 particles was switched to the active Ce6 (dequenched state) via the Azo linker (–N=N–) cleavage in a hypoxic environment. In vitro studies using hypoxia-induced HeLa cells (treated with CoCl₂) revealed that the dHA-Azo-Ce6 particle enhanced photodynamic antitumor inhibition, suggesting its potential as an antitumor drug candidate in response to tumor hypoxia.

PLGA-Based Composites for Various Biomedical Applications

Polymeric materials have been extensively explored in the field of nanomedicine; within them, poly lactic-co-glycolic acid (PLGA) holds a prominent position in micro- and nanotechnology due to its biocompatibility and controllable biodegradability. In this review we focus on the combination of PLGA with different inorganic nanomaterials in the form of nanocomposites to overcome the polymer’s limitations and extend its field of applications. We discuss their physicochemical properties and a variety of well-established synthesis methods for the preparation of different PLGA-based materials. Recent progress in the design and biomedical applications of PLGA-based materials are thoroughly discussed to provide a framework for future research.

Endosomal pH-Responsive Fe-Based Hyaluronate Nanoparticles for Doxorubicin Delivery

In this study, we report pH-responsive metal-based biopolymer nanoparticles (NPs) for tumor-specific chemotherapy. Here, aminated hyaluronic acid (aHA) coupled with 2,3-dimethylmaleic anhydride (DMA, as a pH-responsive moiety) (aHA-DMA) was electrostatically complexed with ferrous chloride tetrahydrate (FeCl₂/4H₂O, as a chelating metal) and doxorubicin (DOX, as an antitumor drug model), producing DOX-loaded Fe-based hyaluronate nanoparticles (DOX@aHA-DMA/Fe NPs). Importantly, the DOX@aHA-DMA/Fe NPs improved tumor cellular uptake due to HA-mediated endocytosis for tumor cells overexpressing CD44 receptors. As a result, the average fluorescent DOX intensity observed in MDA-MB-231 cells (with CD44 receptors) was ~7.9 × 10² (DOX@HA/Fe NPs, without DMA), ~8.1 × 10² (DOX@aHA-DMA_0.36/Fe NPs), and ~9.3 × 10² (DOX@aHA-DMA_0.60/Fe NPs). Furthermore, the DOX@aHA-DMA/Fe NPs were destabilized due to ionic repulsion between Fe²⁺ and DMA-detached aHA (i.e., positively charged free aHA) in the acidic environment of tumor cells. This event accelerated the release of DOX from the destabilized NPs. Our results suggest that these NPs can be promising tumor-targeting drug carriers responding to acidic endosomal pH.

Tumor-Targeting Liposomes with Transient Holes Allowing Intact Rituximab Internally

In this study, the strategy of transient generation of holes in the liposome surface has been shown to enable safe encapsulation of a high-molecular weight antibody (rituximab, M_w ∼140 kDa) within liposomes. These transient holes generated using our magnetoporation method allowed rituximab to safely enter the liposomes, and then the holes were plugged using hyaluronic acid grafted with 3-diethylaminopropylamine (DEAP). In the tumor microenvironment, the resulting liposomal rituximab was destabilized because of the ionization of the DEAP moiety at the acidic pH 6.5, resulting in extensive release of rituximab. Consequently, the rituximab released from the liposomes accumulated at high levels in tumors and bound to the CD20 receptors overexpressed on Burkitt lymphoma Ramos cells. This event led to significant enhancement in tumor cell ablation through rituximab-mediated complement-dependent cytotoxicity and Bcl-2 signaling inhibition-induced cell apoptosis.

Transferrin-Conjugated pH-Responsive γ-Cyclodextrin Nanoparticles for Antitumoral Topotecan Delivery

In this study, we developed γ-cyclodextrin-based multifunctional nanoparticles (NPs) for tumor-targeted therapy. The NPs were self-assembled using a γ-cyclodextrin (γCD) coupled with phenylacetic acid (PA), 2,3-dimethylmaleic anhydride (DMA), poly(ethylene glycol) (PEG), and transferrin (Tf), termed γCDP-(DMA/PEG-Tf) NPs. These γCDP-(DMA/PEG-Tf) NPs are effective in entrapping topotecan (TPT, as a model antitumor drug) resulting from the ionic interaction between pH-responsive DMA and TPT or the host–guest interaction between γCDP and TPT. More importantly, the γCDP-(DMA/PEG-Tf) NPs can induce ionic repulsion at an endosomal pH (~6.0) resulting from the chemical detachment of DMA from γCDP, which is followed by extensive TPT release. We demonstrated that γCDP-(DMA/PEG-Tf) NPs led to a significant increase in cellular uptake and MDA-MB-231 tumor cell death. In vivo animal studies using an MDA-MB-231 tumor xenografted mice model supported the finding that γCDP-(DMA/PEG-Tf) NPs are effective carriers of TPT to Tf receptor-positive MDA-MB-231 tumor cells, promoting drug uptake into the tumors through the Tf ligand-mediated endocytic pathway and increasing their toxicity due to DMA-mediated cytosolic TPT delivery.

Alendronate/cRGD-Decorated Ultrafine Hyaluronate Dot Targeting Bone Metastasis

In this study, we report the hyaluronate dot (dHA) with multiligand targeting ability and a photosensitizing antitumor model drug for treating metastatic bone tumors. Here, the dHA was chemically conjugated with alendronate (ALN, as a specific ligand to bone), cyclic arginine-glycine-aspartic acid (cRGD, as a specific ligand to tumor integrin αvβ3), and photosensitizing chlorin e6 (Ce6, for photodynamic tumor therapy), denoted as (ALN/cRGD)@dHA-Ce6. These dots thus prepared (≈10 nm in diameter) enabled extensive cellular interactions such as hyaluronate (HA)-mediated CD44 receptor binding, ALN-mediated bone targeting, and cRGD-mediated tumor integrin αvβ3 binding, thus improving their tumor targeting efficiency, especially for metastasized MDA-MB-231 tumors. As a result, these dots improved the tumor targeting efficiency and tumor cell permeability in a metastatic in vivo tumor model. Indeed, we demonstrated that (ALN/cRGD)@dHA-Ce6 considerably increased photodynamic tumor ablation, the extent of which is superior to that of the tumor ablation of dot systems with single or double ligands. These results indicate that dHA with multiligand can provide an effective treatment strategy for metastatic bone tumors.

Tumor-Homing pH-Sensitive Extracellular Vesicles for Targeting Heterogeneous Tumors

In this study, we fabricated tumor-homing pH-sensitive extracellular vesicles for efficient tumor treatment. These vesicles were prepared using extracellular vesicles (EVs; BTEVs extracted from BT-474 tumor cells or SKEVs extracted from SK-N-MC tumor cells), hyaluronic acid grafted with 3-(diethylamino)propylamine (HDEA), and doxorubicin (DOX, as a model antitumor drug). Consequently, HDEA/DOX anchored EVs (HDEA@EVs) can interact with origin tumor cells owing to EVs’ homing ability to origin cells. Therefore, EV blends of HDEA@BTEVs and HDEA@SKEVs demonstrate highly increased cellular uptake in both BT-474 and SK-N-MC cells: HDEA@BTEVs for BT-474 tumor cells and HDEA@SKEVs for SK-N-MC tumor cells. Furthermore, the hydrophobic HDEA present in HDEA@EVs at pH 7.4 can switch to hydrophilic HDEA at pH 6.5 as a result of acidic pH-induced protonation of 3-(diethylamino)propylamine (DEAP) moieties, resulting in an acidic pH-activated EVs’ disruption, accelerated release of encapsulated DOX molecules, and highly increased cell cytotoxicity. However, EV blends containing pH-insensitive HA grafted with deoxycholic acid (HDOC) (HDOC@BTEVs and HDOC@SKEVs) showed less cell cytotoxicity for both BT-474 and SK-N-MC tumor cells, because they did not act on EVs’ disruption and the resulting DOX release. Consequently, the use of these tumor-homing pH-sensitive EV blends may result in effective targeted therapies for various tumor cells.

Poisonous Caterpillar-Inspired Chitosan Nanofiber Enabling Dual Photothermal and Photodynamic Tumor Ablation

As caterpillars detect the presence of predators and secrete poison, herein, we show an innovative and highly effective cancer therapeutic system using biocompatible chitosan nanofiber (CNf) installed with a pH-responsive motif that senses tumor extracellular pH, pH_e, prior to delivering dual-modal light-activatable materials for tumor reduction. The filamentous nanostructure of CNf is dynamic during cell interaction and durable in blood circulation. Due to its amine group, CNf uptakes a large amount of photothermal gold nanoparticles (AuNPs, >25 wt %) and photodynamic chlorin e6 (Ce6, >5 wt %). As the innovative CNf approaches tumors, cationic CNf effectively discharges AuNPs connected to the pH-responsive motif via electrostatic repulsion and selectively binds to tumor cells that are generally anionic, via the electrostatic attraction accompanied by CNf. We demonstrated via these actions that the endocytosed Ce6 (on CNf) and AuNPs (free from CNf) significantly elicited tumor cell death under light irradiation. As a result, the synergistic interplay of thermogenesis and photodynamic action was observed to switch on at the pH_e, resulting in a striking reduction in tumor formation and growth rate upon light exposure.

pH and redox dual-responsive copolymer micelles with surface charge reversal for co-delivery of all-trans-retinoic acid and paclitaxel for cancer combination chemotherapy

BACKGROUND

Co-delivery all-trans-retinoic acid (ATRA) and paclitaxel (PTX) is an effective strategy for cancer therapy. However, in many previous reported ATRA conjugated co-delivery systems, the ATRA was released slower than PTX, and the total drug release of ATRA far lower than that of PTX.

PURPOSE

We designed and prepared a pH and redox dual responsive drug delivery system (DA-ss-NPs) co-delivery ATRA and PTX for cancer therapy. The surface charge of DA-ss-NPs could change from negative to positive under tumor slightly acidic microenvironment, and both drugs could be quickly released from DA-ss-NPs under intracellular high concentration of glutathione (GSH).

METHODS

The DA-ss-NPs were constructed by encapsulating PTX into the hydrophobic core of the polymer micelles, in which the polymer was synthesized by conjugating ATRA and 2,3-Dimethylmalefic anhydride (DMA) on side chains of Cystamine dihydrochloride (Cys) modified PEG-b-PAsp (named DA-ss-NPs). The surface charge of DA-ss-NPs under different pH conditions were detected. And the drug release was also measured under different concentration of GSH. The therapeutic effect of DA-ss-NPs were investigated in Human lung cancer A549 cells and A549 tumor-bearing mice.

RESULTS

The zeta potential of DA-ss-NPs was -16.3 mV at pH 7.4, and which changed to 16 mV at pH 6.5. Cell uptake experiment showed that more DA-ss-NPs were internalized by A549 cells at pH 6.5 than that at pH 7.4. In addition, in presence of 10 mM GSH at pH 7.4, about 75%-85% ATRA was released from DA-ss-NPs within 48 h; but less than 20% ATRA was released without GSH. In vivo antitumor efficiency showed that the DA-ss-NPs could affectively inhibite the tumor in compared with control groups.

CONCLUSION

The charge-reversal and GSH-responsive DA-ss-NPs provide an excellent platform for potential tumor therapy.

Gold Nanoparticles Bearing a Tumor pH-Sensitive Cyclodextrin Cap

We report functional gold nanoparticles (AuNPs) with a pH-sensitive γ-cyclodextrin (CD) cap. These particles include two chargeable CD molecules on their surface. CD with dopamine and amine (NH₂) groups (hereafter termed as dCD-NH₂) was anchored to the gold surface and then electrostatically complexed with the CD with 2,3-dimethylmaleic acid (DMA) and chlorin e6 (Ce6) (hereafter termed as cCD-DMA), producing an ionic complex consisting of dCD-NH₂ and cCD-DMA. Under the acidic environment (pH 6.8) existing in most solid tumors, the ionic complex was destabilized because of the decoupling of DMA, resulting in the release of cCD (without DMA) from the AuNPs, resulting in extensive tumoral uptake of AuNPs with dCD-NH₂ (because of their electrostatic attraction to tumor cells). This event resulted in a significant increase in the efficiency of cellular AuNP uptake and light-driven (AuNP-mediated photothermal and Ce6-mediated photodynamic) ablation of acidic solid tumors, suggesting marked potential for tumor therapy.

Hyaluronate dots for highly efficient photodynamic therapy

Nanoscale particles, such as quantum dots and carbon dots, are important materials for use in sensing and treating irregular biological events, but their versatility for biomedical applications are usually limited by their undesirable properties such toxicity and non-degradability. Here, we report biofunctional hyaluronic acid (HA) dots containing biodegradable/biocompatible HA. HA dots were prepared by conjugating multiple HA molecules to C₆₀ (used as a base dot) without any hydrothermal treatment. The hydroxyl groups of HA completely linked to all π-π carbon bonds in C₆₀. The chemically synthesized HA dots (Mn=16.1kDa) were 2nm in diameter, soluble in aqueous solution, and possessed multiple functional (carboxyl) groups. The HA dots were biofunctional, enabling highly efficient binding to CD44 receptors overexpressed on in vitro/in vivo tumors. With light illumination, we demonstrated that the HA dots bearing a photosensitizing model drug (chlorin e6: Ce6) resulted in a significant enhancement in in vitro/in vivo tumor cell ablation. We believe that this approach offers a new strategy to create biopolymer dots.

Shear-responsive injectable supramolecular hydrogel releasing doxorubicin loaded micelles with pH-sensitivity for local tumor chemotherapy

In this study, glycol chitosan-Pluronic F127 conjugate (GC-PF127), produced by an amidation reaction between terminal-carboxylated PF127 and glycol chitosan (GC), was used to prepare doxorubicin (DOX)-loaded micelles. The DOX/GC-PF127 micelles produced at optimal conditions had sizes of about 150nm and pH-sensitive surface charges. DOX/GC-PF127 hydrogel formed after addition of α-cyclodextrin into DOX/GC-PF127 micelle solution. The hydrogel had good shear-responsive, injectable and rapid recovery properties. In vitro release experiment confirmed that the hydrogel could sustainedly release DOX/GC-PF127 micelles via the dissociation of the hydrogel. After peritumoral injection into H22 tumor-bearing mice, the hydrogel could greatly increase DOX accumulation in tumor tissue and synchronously avoid DOX accumulation in normal tissues including heart. At similar total DOX dose administrated, the tumors of free DOX treatment group grew slowly after thrice intravenous injections, the tumors of the micelle group did not grow after twice intravenous injections, and the tumors of the hydrogel group disappeared almost after once peritumoral injection. This study demonstrates that injectable DOX/GC-PF127 hydrogel, which can sustainedly release DOX-loaded micelles with tumor-targeting function, is a promising system for local tumor chemotherapy.

Recent advances in engineered chitosan-based nanogels for biomedical applications

Recent progress in the preparation and biomedical applications of engineered chitosan-based nanogels has been comprehensively reviewed.

Enhanced proliferation inhibition of HL60 cells treated by synergistic all-trans retinoic acid/blue light/nanodiamonds

This work explores a strategy using drug all-transretinoic (ATRA) combined with nanodiamond (ND) and blue light (BL) irradiation on the typical HL60 cell line, to establish a approach for improving the treatment efficacy of human leukemia cells.

Development of pH-responsive starch–glycol chitosan nanogels for proapoptotic (KLAKLAK)2 peptide delivery

In this study, we report pH-responsive polysaccharidic nanogels for cytosolic peptide delivery. We conjugated starch to water-soluble glycol chitosan and pH-responsive 3-diethylaminopropylamine (starch–(glycol chitosan–3-diethylaminopropylamine)). Starch–(glycol chitosan–3-diethylaminopropylamine) self-organizes in aqueous solution, with the glycol chitosan blocks on the hydrophilic outer shell and starch and 3-diethylaminopropylamine blocks in the hydrogel inner core. The experimental results demonstrated that the protonation of 3-diethylaminopropylamine at pH 6.0 (endosomal pH) allowed for accelerated release of the encapsulated D-(KLAKLAK)2 proapoptotic peptide from the nanogels as a result of electrostatic repulsion between D-(KLAKLAK)2 and 3-diethylaminopropylamine. A hemolysis test using red blood cell membranes (as an endosomal membrane model) revealed the excellent endosomolytic activity of these nanogels, which likely stems from the proton-sponge effect of 3-diethylaminopropylamine at pH 6.0. As a result, these nanogels resulted in increased KB tumor cell ablation.

pH-Responsive globular poly(ethylene glycol) for photodynamic tumor therapy

In this study, we report the development of extremely small-sized globular poly(ethylene glycol) (gPEG) that can specifically recognize tumor acidic pH. gPEG coupled with chlorin e6 (Ce6, a photosensitizing drug) and 2,3-dimethylmaleic acid (DMA, as a pH-responsive moiety) (gPEG-Ce6-DMA, particle size: 3-4nm in diameter) was easily dispersed in phosphate buffered saline (PBS) without any of the nanoparticle fabrication steps. We observed that gPEG-Ce6-DMA displayed pH-dependent zeta-potential changes due to coupling (at pH 7.4) or decoupling (at pH 6.8-6.0) of DMA. As a result, the uptake of gPEG-Ce6-DMA was significantly increased in tumors at acidic pH, likely due to the decoupling of DMA (backing cationic primary amines). As a result, the preferential cellular uptake of gPEG-Ce6-DMA at acidic pH allowed for a significant enhancement of in vitro/in vivo photodynamic tumor cell ablation under light illumination.

Preparation of iron oxide nanoparticles functionalized with Y-shaped ligands for brain tumor targeting

In this study, we developed functionalized iron oxide nanoparticles for brain tumor targeting. The iron oxide (Fe₃O₄) particles were stabilized with pluronic F127 and coupled with dopamine-terminated Y-shaped ligands (Tat peptide and transferrin) as a result of the noncovalent conjugation of dopamine (of Y-shaped ligands) and the iron oxide nanoparticles. Here, the hydrophobic domain of pluronic F127 coated on the iron oxide nanoparticles enabled the absorption of a model photosensitizing antitumor drug (chlorin e6) in the core/shell interface of the nanoparticles. The experimental results demonstrated that the Y-shaped ligands on the nanoparticles enabled a significant enhancement of in vitro/in vivo cellular uptake for human primary glioblastoma U87-MG cells as a result of multivalent endocytosis by Y-shaped ligands (transferrin receptor-mediated endocytosis and the following Tat peptide-mediated cellular interaction). Furthermore, the Ce6-loaded nanoparticles showed significant enhancement of in vitro/in vivo photodynamic U87-MG cell ablation under light illumination.

Activated Charge-Reversal Polymeric Nano-System: The Promising Strategy in Drug Delivery for Cancer Therapy

Various polymeric nanoparticles (NPs) with optimal size, tumor-targeting functionalization, or microenvironment sensitive characteristics have been designed to solve several limitations of conventional chemotherapy. Nano-sized polymeric drug carrier systems have remarkably great advantages in drug delivery and cancer therapy, which are still plagued with severe deficiencies, especially insufficient cellular uptake. Recently, surface charge of medical NPs has been demonstrated to play an important role in cellular uptake. NPs with positive charge show higher affinity to anionic cell membranes such that with more efficient cellular internalization, but otherwise cause severe aggregation and fast clearance in circulation. Thus, surface charge-reversal NPs, specifically activated at the tumor site, have shown to elegantly resolve the enhanced cellular uptake in cancer cells vs. non-specific protein adsorption dilemma. Herein, this review mainly focuses on the effect of tumor-site activated surface charge reversal NPs on tumor treatment, including the activated mechanisms and various applications in suppressing cancer cells, killing cancer stem cell and overcoming multidrug resistance, with the emphasis on recent research in these fields. With the comprehensive and in-depth understanding of the activated surface charge reversal NPs, this approach might arouse great interest of scientific research on enhanced efficient polymeric nano-carriers in cancer therapy.

Facile fabrication of highly soluble, extremely small-sized drug carriers using globular poly(ethylene glycol)

We report extremely small-sized drug-carrying globular poly(ethylene glycol) particles. These particles were prepared using fullerene (C60) as a backbone structure and poly(ethylene glycol) as a hydrophilic shell. All π–π carbon bonds in C60 were combined with poly(ethylene glycol), which form a “globular nano-cage” with a hollow core (originating from the soccer-ball-shaped truncated icosahedron of C60) and the poly(ethylene glycol) shell. Subsequently, we constructed chlorin e6-conjugated globular poly(ethylene glycol). The obtained globular poly(ethylene glycol)–chlorin e6 (average 3.6 nm in diameter) was soluble in aqueous solution and enabled improved singlet oxygen generation. The preferential cellular uptake of globular poly(ethylene glycol)–chlorin e6 resulted in significant enhancement of in vitro or in vivo photodynamic tumor cell ablation under light illumination. Our approach offers a versatile strategy to create extremely small-sized drug carriers using a biocompatible polymer for various biomedical applications.

Activable Cell-Penetrating Peptide Conjugated Prodrug for Tumor Targeted Drug Delivery

In this paper, an activable cell-penetrating peptide (CR8G3PK6, ACPP) with a shielding group of 2,3-dimethylmaleic anhydride (DMA) was conjugated with antitumor drug doxorubicin (DOX) to construct a novel prodrug (DOX-ACPP-DMA) for tumor targeted drug delivery. The shielding group of DMA linked to the primary amines of K6 through the amide bond was used to block the cell-penetrating function of the polycationic CPP (R8) through intramolecular electrostatic attraction at physiological pH 7.4. At tumor extracellular pH 6.8, the hydrolysis of DMA led to charge reversal, activating the pristine function of CPP for improved cellular uptake by tumor cells. Confocal laser scanning microscopy (CLSM) and flow cytometry studies revealed that the cellular uptake of DOX-ACPP-DMA was significantly enhanced after acid-triggered activation in both HeLa and COS7 cells. After cell internalization, the overexpressed intracellular proteases would further trigger drug release in cells. Both in vitro and in vivo investigations showed that the peptidic prodrug exhibited significant tumor growth inhibition and demonstrated great potential for tumor therapy.

Preparation of poly(β-L-malic acid)-based charge-conversional nanoconjugates for tumor-specific uptake and cellular delivery

In this study, a multifunctional poly(β-L-malic acid)-based nanoconjugate with a pH-dependent charge conversional characteristic was developed for tumor-specific drug delivery. The short branched polyethylenimine-modified poly(β-L-malic acid) (PEPM) was first synthesized. Then, the fragment HAb18 F(ab′)₂ and 2,3-dimethylmaleic anhydride were covalently attached to the PEPM to form the nanoconjugate, HDPEPM. In this nanoconjugate, the 2,3-dimethylmaleic anhydride, the shielding group, could shield the positive charge of the conjugate at pH 7.4, while it was selectively hydrolyzed in the tumor extracellular space (pH 6.8) to expose the previously-shielded positive charge. To study the anticancer activity, the anticancer drug, doxorubicin, was covalently attached to the nanoconjugate. The doxorubicin-loaded HDPEPM nanoconjugate was able to efficiently undergo a quick charge conversion from −11.62 mV to 9.04 mV in response to the tumor extracellular pH. The electrostatic interaction between the positively charged HDPEPM nanoconjugates and the negatively charged cell membrane significantly enhanced their cellular uptake, resulting in the enhanced anticancer activity. Also, the tumor targetability of the nanoconjugates could be further improved via the fragment HAb18 F(ab′)₂ ligand–receptor-mediated tumor cell-specific endocytosis.

Hoechst 33258–conjugated hyaluronated fullerene for efficient photodynamic tumor therapy and necrotic tumor targeting

In this study, we synthesized a Hoechst 33258–conjugated hyaluronated fullerene consisting of Hoechst 33258 (as a target moiety to detect necrotic tumor cells), hyaluronic acid (as a target polymer to bind the CD44 receptor overexpressed on the surface of tumor cells), and fullerene (as a photosensitizing agent). This conjugate self-assembled to form nanoparticles consisting of a hydrophilic block (Hoechst 33258 and hyaluronic acid) and a lipophilic block (fullerene). We utilized these nanoparticles to improve the antitumor efficacy via photodynamic tumor therapy. The HCT-116 cells that were damaged after the first photodynamic tumor therapy (using hyaluronated fullerene nanoparticles) were again targeted using Hoechst 33258–conjugated hyaluronated fullerene nanoparticles (detecting necrotic tissues). The experimental results revealed that the second photodynamic tumor therapy using Hoechst 33258–conjugated hyaluronated fullerene nanoparticles caused significant increases in the in vitro phototoxicity and the in vivo tumor inhibition, thereby suggesting their pharmaceutical potential for designing effective multiple photodynamic tumor therapy treatments.

Photodynamic tumor therapy of nanoparticles with chlorin e6 sown in poly(ethylene glycol) forester

We developed novel photosensitizing drug-carrying nanoparticles with poly(ethylene glycol) (PEG) forester.

Self-regulated multifunctional collaboration of targeted nanocarriers for enhanced tumor therapy

Exploring ideal nanocarriers for drug delivery systems has encountered unavoidable hurdles, especially the conflict between enhanced cellular uptake and prolonged blood circulation, which have determined the final efficacy of cancer therapy. Here, based on controlled self-assembly, surface structure variation in response to external environment was constructed toward overcoming the conflict. A novel micelle with mixed shell of hydrophilic poly(ethylene glycol) PEG and pH responsive hydrophobic poly(β-amino ester) (PAE) was designed through the self-assembly of diblock amphiphilic copolymers. To avoid the accelerated clearance from blood circulation caused by the surface exposed targeting group c(RGDfK), here c(RGDfK) was conjugated to the hydrophobic PAE and hidden in the shell of PEG at pH 7.4. At tumor pH, charge conversion occurred, and c(RGDfK) stretched out of the shell, leading to facilitated cellular internalization according to the HepG2 cell uptake experiments. Meanwhile, the heterogeneous surface structure endowed the micelle with prolonged blood circulation. With the self-regulated multifunctional collaborated properties of enhanced cellular uptake and prolonged blood circulation, successful inhibition of tumor growth was achieved from the demonstration in a tumor-bearing mice model. This novel nanocarrier could be a promising candidate in future clinical experiments.

A molecular zipping/unzipping nano-vehicles sensitive to tumor extracellular pH

A new class of pH- responsive multivalent host–guest interactions to manipulate polypeptide-based nano-vehicles was developed. Poly(l-lysine) (poly(Lys)) grafted with β-cyclodextrin and 2,3-dimethylmaleic acid was coupled with oleic acid. This new polymer was utilized to fabricate pH-responsive nano-vehicles for antitumor drug doxorubicin delivery. The host–guest (zipping) interaction between β-cyclodextrin and 2,3-dimethylmaleic acid moieties and the hydrophobic interaction between the oleic acid molecules contributed to form self-assembled nano-vehicles. 2,3-Dimethylmaleic acid moieties were highly degradable at a slightly acidic pH (~pH 6.8). These nano-vehicles increased the release of the encapsulated doxorubicin content (by the unzipping interaction between β-cyclodextrin and degraded 2,3-dimethylmaleic acid moieties) when the pH of the solution decreased to 6.8. This event caused a significant increase in the efficiency of cellular doxorubicin uptake and in vitro tumor inhibition.

Multimeric grain-marked micelles for highly efficient photodynamic therapy and magnetic resonance imaging of tumors

Multimeric grain-marked micelles consisting of an inner core micelle (for Fe3O4 encapsulation) and outer multi-grain micelles (for chlorin e6 (Ce6, a model drug) encapsulation) were fabricated using a micelle-to-micelle conjugation method. Grain micelles (mono-thiol functionalized micelles) were chemically linked to the surface of the core micelle (multi-maleimide functionalized micelle). These micelles enable discrete compartments for Ce6 and iron oxide (Fe3O4) that enable a significantly increased in vivo photodynamic tumor inhibition while preserving high contrast magnetic resonance (MR) imaging of the tumor in vivo.

A charge-switchable, four-armed polymeric photosensitizer for photodynamic cancer therapy

A water-soluble, charge-switchable, four-armed polymeric photosensitizer (C4P-PS), in which charge switching is pH dependent, has been designed as a new class of photosensitizer for photodynamic cancer therapy.

pH-sensitive short worm-like micelles targeting tumors based on the extracellular pH

We developed novel photosensitizing drug-carrying worm-like micelles using a pH-sensitive AB₂ miktoarm block copolymer consisting of one methoxy-poly(ethylene glycol) (mPEG) block (A) and two 3-diethylaminopropylated poly(l-lysine) [poly(Lys-DEAP)] blocks (B₂).