Stimuli-Responsive Polymersomes: Reshaping the Immunosuppressive Tumor Microenvironment.

The progression of cancer involves mutations in normal cells, leading to uncontrolled division and tissue destruction, highlighting the complexity of tumor microenvironments (TMEs). Immunotherapy has emerged as a transformative approach, yet the balance between efficacy and safety remains a challenge. Nanoparticles such as polymersomes offer the possibility to precisely target tumors, deliver drugs in a controlled way, effectively modulate the antitumor immunity, and notably reduce side effects. Herein, stimuli-responsive polymersomes, with capabilities for carrying multiple therapeutics, are highlighted for their potential in enhancing antitumor immunity through mechanisms like inducing immunogenic cell death and activating STING (stimulator of interferon genes), etc. The recent progress of utilizing stimuli-responsive polymersomes to reshape the TME is reviewed here. The advantages and limitations to applied stimuli-responsive polymersomes are outlined. Additionally, challenges and future prospects in leveraging polymersomes for cancer therapy are discussed, emphasizing the need for future research and clinical translation.

Exceedingly Small Gadolinium Oxide Nanoparticles with Remarkable Relaxivities for Magnetic Resonance Imaging of Tumors.

Gd chelates have occupied most of the market of magnetic resonance imaging (MRI) contrast agents for decades. However, there have been some problems (nephrotoxicity, non-specificity, and low r1 ) that limit their applications. Herein, a wet-chemical method is proposed for facile synthesis of poly(acrylic acid) (PAA) stabilized exceedingly small gadolinium oxide nanoparticles (ES-GON-PAA) with an excellent water dispersibility and a size smaller than 2.0 nm, which is a powerful T1 -weighted MRI contrast agent for diagnosis of diseases due to its remarkable relaxivities (r1 = 70.2 ± 1.8 mM-1 s-1 , and r2 /r1 = 1.02 ± 0.03, at 1.5 T). The r1 is much higher and the r2 /r1 is lower than that of the commercial Gd chelates and reported gadolinium oxide nanoparticles (GONs). Further ES-GON-PAA is developed with conjugation of RGD2 (RGD dimer) (i.e., ES-GON-PAA@RGD2) for T1 -weighted MRI of tumors that overexpress RGD receptors (i.e., integrin αv ß3 ). The maximum signal enhancement (ΔSNR) for T1 -weighted MRI of tumors reaches up to 372 ± 56% at 2 h post-injection of ES-GON-PAA@RGD2, which is much higher than commercial Gd-chelates (<80%). Due to the high biocompatibility and high tumor accumulation, ES-GON-PAA@RGD2 with remarkable relaxivities is a promising and powerful T1 -weighted MRI contrast agent.

Anisamide-Decorated pH-Sensitive Degradable Chimaeric Polymersomes Mediate Potent and Targeted Protein Delivery to Lung Cancer Cells.

In spite of their high potency and specificity, few protein drugs have advanced to the clinical settings due to lack of safe and efficient delivery vehicles. Here, novel anisamide-decorated pH-sensitive degradable chimaeric polymersomes (Anis-CPs) were designed, prepared, and investigated for efficient and targeted delivery of apoptotic protein, granzyme B (GrB), to lung cancer cells. Anis-CPs were readily prepared with varying Anis surface densities from anisamide end-capped poly(ethylene glycol)-b-poly(2,4,6- trimethoxybenzylidene-1,1,1-tris(hydroxymethyl)ethane methacrylate)-b-poly(acrylic acid) (Anis-PEG-PTTMA-PAA) and PEG-PTTMA-PAA copolymers. Using cytochrome C (CC) as a model protein, Anis-CPs displayed high protein loading efficiencies (40.5-100%) and loading contents (up to 16.8 wt %). CC-loaded Anis-CPs had narrow distribution (PDI 0.04-0.13) and small sizes ranging from 152 to 171 nm, which increased with increasing CC contents. Notably, the release of proteins from Anis-CPs was accelerated under mildly acidic conditions, due to the hydrolysis of acetal bonds in PTTMA. MTT assays showed that GrB-loaded Anis-CPs (GrB-Anis-CPs) displayed high targetability to sigma receptor overexpressing cancer cells such as H460 and PC-3 cells. For example, GrB-Anis-CPs exhibited increasing antitumor efficacy to H460 cells with increasing Anis contents from 0 to 80%. The antitumor activity of GrB-Anis-CPs was significantly reduced upon pretreating H460 cells with haloperidol (a competitive antagonist). Notably, the half-maximal inhibitory concentrations (IC50) of GrB-Anis70-CPs were determined to be 6.25 and 5.94 nM for H460 and PC-3 cells, respectively, which were 2-3 orders of magnitude lower than that of chemotherapeutic drugs, such as paclitaxel. Flow cytometry studies demonstrated that GrB-Anis70-CPs induced widespread apoptosis of H460 cells. The confocal laser scanning microscopy (CLSM) experiments using FITC-labeled CC-loaded Anis-CPs confirmed fast internalization and intracellular protein release into H460 cells. GrB-Anis-CPs with high potency and specificity are particularly interesting for targeted therapy of lung cancers.

A Triple-Responsive Polymeric Prodrug Nanoplatform with Extracellular ROS Consumption and Intracellular H2O2 Self-Generation for Imaging-Guided Tumor Chemo-Ferroptosis-Immunotherapy.

High reactive oxygen species (ROS) levels in tumor microenvironment (TME) impair both immunogenic cell death (ICD) efficacy and T cell activity. Furthermore, tumor escapes immunosurveillance via programmed death-1/programmed death ligand-1 (PD-L1) signal, and the insufficient intracellular hydrogen peroxide weakens ferroptosis efficacy. To tackle the above issues, a glutathione (GSH)/ROS/pH triple-responsive prodrug nanomedicine that encapsulates Fe2O3 nanoparticle via electrostatic interaction is constructed for magnetic resonance imaging (MRI)-guided multi-mode theranostics with chemotherapy/ferroptosis/immunotherapy. The diselenide bond consumes ROS in TME to increase T cells and ICD efficacy, the cleavage of which facilitates PD-L1 antagonist D peptide release to block immune checkpoint. After intracellular internalization, Fe2O3 nanoparticle is released in the acidic endosome for MRI simultaneously with lipid peroxides generation for tumor ferroptosis. Doxorubicin is cleaved from polymers in the condition of high intracellular GSH level accompanied by tumor ICD, which simultaneously potentiates ferroptosis by NADPH oxidase mediated H2O2 self-generation. In vivo results indicate that the nanoplatform strengthens tumor ICD, induces cytotoxic T lymphocytes proliferation, inhibits 4T1 tumor regression and metastasis, and prolongs survival median. In all, a new strategy is proposed in strengthening ICD and T cells activity cascade with ferroptosis as well as immune checkpoint blockade for effective tumor immunotherapy.

A polymeric nanoplatform enhances the cGAS-STING pathway in macrophages to potentiate phagocytosis for cancer immunotherapy.

Immunosuppressive tumor-associated macrophages (TAMs) account for a high proportion of the tumor tissue and significantly impede immunoefficacy. Furthermore, the signal regulatory protein α (SIRPα) expressed in TAMs adversely correlates with macrophage activation and phagocytosis, resulting in immunosurveillance escape. To address these difficulties, a mannose-modified, pH-responsive nanoplatform with resiquimod (R848) and 2', 3'-cyclic GMP-AMP (cGAMP) co-encapsulation (named M-PNP@R@C) is designed to polarize TAMs and lower SIRPα expression. The co-delivery of R848 and cGAMP synergistically facilitates the polarization of TAMs from the anti-inflammatory M2 phenotype into the pro-inflammatory M1 phenotype, thereby enhancing antitumor immunotherapy. Remarkably, activation of the cGAMP-mediated stimulator of interferon genes (STING) in TAMs significantly downregulates the expression of SIRPα, which synergizes with the cluster of differentiation 47 (CD47) antibody for the dual blockade of the CD47-SIRPα axis. Further analysis of single-cell RNA sequencing indicates that STING activation downregulates SIRPα by regulating intracellular fatty acid oxidation metabolism. In vivo studies indicate that M-PNP@R@C significantly inhibits tumor growth with a potent antitumor immune response in melanoma graft tumor models. After synergy with anti-CD47, the double blockade strategies of the SIRPα/CD47 axis result in a notable inhibition of lung metastasis. A prolonged survival rate is observed after combination treatment with CD47 and programmed death ligand-1 antibodies for the triple immune checkpoint blockade. In summary, our study provides original insights into the potential role of the STING pathway in macrophage-based immunotherapy, thus offering a potential combinatorial strategy for cancer therapy.

Ligand-directed reduction-sensitive shell-sheddable biodegradable micelles actively deliver doxorubicin into the nuclei of target cancer cells.

The therapeutic performance of biodegradable micellar drugs is far from optimal due to existing challenges like poor tumor cell uptake and intracellular drug release. Here, we report on ligand-directed reduction-sensitive shell-sheddable biodegradable micelles based on poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) copolymer actively delivering doxorubicin (DOX) into the nuclei of target cancer cells, inducing superb in vitro antitumor effects. The micelles were constructed from PEG-SS-PCL and galactose-PEG-PCL (Gal-PEG-PCL) block copolymers, in which Gal-PEG-PCL was designed with a longer PEG than that in PEG-SS-PCL (6.0 vs 5.0 kDa) to fully expose Gal ligands onto the surface of micelles for effective targeting to hepatocellular carcinoma cells. PEG-SS-PCL combining with 10 or 20 wt % of Gal-PEG-PCL formed uniform micelles with average sizes of 56.1 and 58.2 nm (denoted as PEG-SS-PCL/Gal10 and PEG-SS-PCL/Gal20, respectively). The in vitro release studies showed that about 81.1 and 75.0% DOX was released in 12 h from PEG-SS-PCL/Gal10 and PEG-SS-PCL/Gal20 micelles under a reducing condition containing 10 mM dithiothreitol (DTT). In contrast, minimal DOX release (<12%) was observed for PEG-SS-PCL/Gal10 and PEG-SS-PCL/Gal20 micelles under nonreducing conditions as well as for reduction-insensitive Gal-PEG-PCL and PEG-PCL/Gal20 micelles in the presence of 10 mM DTT. MTT assays in HeLa and HepG2 cells showed that DOX-loaded PEG-SS-PCL/Gal20 micelles exhibited apparent targetability and significantly enhanced antitumor efficacy toward asialoglycoprotein receptor (ASGP-R)-overexpressing HepG2 cells with a particularly low half maximal inhibitory concentration (IC50) of 1.58 µg DOX equiv/mL, which was comparable to free DOX and approximately six times lower than that for nontargeting PEG-SS-PCL counterparts under otherwise the same conditions. Interestingly, confocal microscopy observations using FITC-labeled PEG-SS-PCL/Gal20 micelles showed that DOX was efficiently delivered and released into the nuclei of HepG2 cells in 8 h. Flow cytometry revealed that cellular DOX level in HepG2 cells treated with DOX-loaded PEG-SS-PCL/Gal20 micelles was much greater than that with reduction-insensitive PEG-PCL/Gal20 and nontargeting PEG-SS-PCL controls, signifying the importance of combining shell-shedding and active targeting. Ligand-directed, reduction-sensitive, shell-sheddable, and biodegradable micelles have emerged as a versatile and potent platform for targeted cancer chemotherapy.

Oral insulin delivery by epithelium microenvironment-adaptive nanoparticles.

Oral protein drug delivery using nano-based systems remains challenging, as contradictory surface properties are required for efficient navigation through the intestinal mucus and epithelium barriers. Therefore, new nanoplatforms with tunable surface properties in vivo are urgently needed. Inspired by the slightly acidic microclimate of the jejunal epithelial surface, we report a novel epithelium microenvironment-adaptive nanoplatform that undergoes a hydrophilicity-hydrophobicity transition at the epithelial surface. First, we synthesized and characterized a biodegradable copolymer consisting of PEG and PLGA building blocks linked by a hydrazone bond (PLGA-Hyd-PEG) to fabricate the pH-sensitive core-shell architecture of an oral insulin system. Then we loaded the system as a freeze-dried powder into enteric-coated capsules. PLGA-Hyd-PEG nanoparticles showed excellent drug protection and rapid mucus penetration owing to the high stability of the PEG coating in jejunal fluid. In the acidic microenvironment of the jejunal epithelial surface (pH ~5.5), PEG was rapidly cleaved and the hydrazone bond was hydrolyzed, converting the nanoparticle surface from hydrophilic to hydrophobic, thereby facilitating internalization into cells. Pharmacodynamic studies showed that PLGA-Hyd-PEG nanoparticles resulted in significant decrease in blood glucose level after intrajejunal administration in both normal and diabetic rats relative to control nanoparticles. In addition, enteric-coated capsules containing PLGA-Hyd-PEG nanoparticles reduced blood glucose by 35% for up to 10 h after oral administration to diabetic rats. Our findings provide a new strategy for regulating the surface properties of nanoparticles for efficient oral drug delivery.

Photodynamic-Chemodynamic Cascade Reactions for Efficient Drug Delivery and Enhanced Combination Therapy.

Nanomedicines with photodynamic therapy and reactive oxygen species (ROS)-triggered drug release capabilities are promising for cancer therapy. However, most of the nanomedicines based on ROS-responsive nanocarriers still suffer from serious ROS consumption during the triggered drug release process. Herein, a photodynamic-chemodynamic cascade strategy for the design of drug delivery nanosystem is proposed. A doxorubicin hydrochloride-loaded ROS-responsive polymersome (DOX-RPS) is prepared via the self-assembly of amphiphilic poly(ethylene glycol)-poly(linoleic acid) and poly(ethylene glycol)-(2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-α)-iron chelate (PEG-HPPH-Fe). The RPS can effectively deliver a drug to tumor site through passive targeting effect. Upon laser irradiation, the photosensitizer HPPH can efficiently generate ROS, which further causes in situ oxidation of linoleic acid chain and subsequent RPS structural destruction, permitting triggered drug release. Intriguingly, catalyzed by HPPH-Fe, ROS will be regenerated from linoleic acid peroxide through a chemodynamic process. Therefore, ROS-triggered drug release can be achieved without ROS over-consumption. The in vitro and in vivo results confirmed ROS generation, triggered drug release behavior, and potent antitumor effect of the DOX-RPS. This photodynamic-chemodynamic cascade strategy provides a promising approach for enhanced combination therapy.

Targeted scavenging of extracellular ROS relieves suppressive immunogenic cell death.

Immunogenic cell death (ICD) and tumour-infiltrating T lymphocytes are severely weakened by elevated reactive oxygen species (ROS) in the tumour microenvironment. It is therefore of critical importance to modulate the level of extracellular ROS for the reversal of immunosuppressive environment. Here, we present a tumour extracellular matrix (ECM) targeting ROS nanoscavenger masked by pH sensitive covalently crosslinked polyethylene glycol. The nanoscavenger anchors on the ECM to sweep away the ROS from tumour microenvironment to relieve the immunosuppressive ICD elicited by specific chemotherapy and prolong the survival of T cells for personalized cancer immunotherapy. In a breast cancer model, elimination of the ROS in tumour microenvironment elicited antitumour immunity and increased infiltration of T lymphocytes, resulting in highly potent antitumour effect. The study highlights a strategy to enhance the efficacy of cancer immunotherapy by scavenging extracellular ROS using advanced nanomaterials.

Smart Nanovesicle-Mediated Immunogenic Cell Death through Tumor Microenvironment Modulation for Effective Photodynamic Immunotherapy.

Combination therapy that could better balance immune activation and suppressive signals holds great potential in cancer immunotherapy. Herein, we serendipitously found that the pH-responsive nanovesicles (pRNVs) self-assembled from block copolymer polyethylene glycol-b-cationic polypeptide can not only serve as a nanocarrier but also cause immunogenic cell death (ICD) through preapoptotic exposure of calreticulin. After coencapsulation of a photosensitizer, 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) and an indoleamine 2,3-dioxygenase inhibitor, indoximod (IND), pRNVs/HPPH/IND at a single low dose elicited significant antitumor efficacy and abscopal effect following laser irradiation in a B16F10 melanoma tumor model. Treatment efficacy attributes to three key factors: (i) singlet oxygen generation by HPPH-mediated photodynamic therapy (PDT); (ii) increased dendritic cell (DC) recruitment and immune response provocation after ICD induced by pRNVs and PDT; and (iii) tumor microenvironment modulation by IND via enhancing P-S6K phosphorylation for CD8+ T cell development. This study exploited the nanocarrier to induce ICD for the host's immunity activation. The "all-in-one" smart nanovesicles allow the design of multifunctional materials to strengthen cancer immunotherapy efficacy.

Zwitterionic-to-cationic charge conversion polyprodrug nanomedicine for enhanced drug delivery.

Zwitterionic surface modification is a promising strategy for nanomedicines to achieve prolonged circulation time and thus effective tumor accumulation. However, zwitterion modified nanoparticles suffer from reduced cellular internalization efficiency. Methods: A polyprodrug-based nanomedicine with zwitterionic-to-cationic charge conversion ability (denoted as ZTC-NMs) was developed for enhanced chemotherapeutic drug delivery. The polyprodrug consists of pH-responsive poly(carboxybetaine)-like zwitterionic segment and glutathione-responsive camptothecin prodrug segment. Results: The ZTC-NMs combine the advantages of zwitterionic surface and polyprodrug. Compared with conventional zwitterionic surface, the ZTC-NMs can respond to tumor microenvironment and realize ZTC surface charge conversion, thus improve cellular internalization efficiency of the nanomedicines. Conclusions: This ZTC method offers a strategy to promote the drug delivery efficiency and therapeutic efficacy, which is promising for the development of cancer nanomedicines.

Generic synthesis of small-sized hollow mesoporous organosilica nanoparticles for oxygen-independent X-ray-activated synergistic therapy.

The success of radiotherapy relies on tumor-specific delivery of radiosensitizers to attenuate hypoxia resistance. Here we report an ammonia-assisted hot water etching strategy for the generic synthesis of a library of small-sized (sub-50 nm) hollow mesoporous organosilica nanoparticles (HMONs) with mono, double, triple, and even quadruple framework hybridization of diverse organic moieties by changing only the introduced bissilylated organosilica precursors. The biodegradable thioether-hybridized HMONs are chosen for efficient co-delivery of tert-butyl hydroperoxide (TBHP) and iron pentacarbonyl (Fe(CO)5). Distinct from conventional RT, radiodynamic therapy (RDT) is developed by taking advantage of X-ray-activated peroxy bond cleavage within TBHP to generate •OH, which can further attack Fe(CO)5 to release CO molecules for gas therapy. Detailed in vitro and in vivo studies reveal the X-ray-activated cascaded release of •OH and CO molecules from TBHP/Fe(CO)5 co-loaded PEGylated HMONs without reliance on oxygen, which brings about remarkable destructive effects against both normoxic and hypoxic cancers.

Boosting RNAi therapy for orthotopic glioblastoma with nontoxic brain-targeting chimaeric polymersomes.

Glioblastoma with intracranial infiltrative growth remains an incurable disease mainly owing to existence of blood brain barrier (BBB) and off-target drug toxicity. RNA interference (RNAi) with a high specificity and low toxicity emerges as a new treatment modality for glioblastoma. The clinical application of RNAi technology is, however, hampered by the absence of safe and brain-targeting transfection agents. Here, we report on angiopep-2 peptide-decorated chimaeric polymersomes (ANG-CP) as a nontoxic and brain-targeting non-viral vector to boost the RNAi therapy for human glioblastoma in vivo. ANG-CP shows excellent packaging and protection of anti-PLK1 siRNA (siPLK1) in its lumen while quickly releasing payloads in a cytoplasmic reductive environment. Notably, in vitro experiments demonstrate that ANG-CP can effectively permeate the bEnd.3 monolayer, transport siRNA into the cytosol of U-87 MG glioblastoma cells via the LRP-1-mediated pathway, and significantly silence PLK1 mRNA and corresponding oncoprotein in U-87 MG cells. ANG-CP greatly prolongs the siPLK1 circulation time and enhances its accumulation in glioblastoma. RNAi with siPLK1 induces a strong anti-glioblastoma effect and significantly improves the survival time of glioblastoma carrying mice.

Granzyme B-loaded, cell-selective penetrating and reduction-responsive polymersomes effectively inhibit progression of orthotopic human lung tumor in vivo.

The clinical use of protein therapeutics with intracellular targets is hampered by its in vivo fragility and low cell permeability. Here, we report that cell-selective penetrating and reduction-responsive polymersomes (CPRPs) mediate high-efficiency targeted delivery of granzyme B (GrB) to orthotopic human lung tumor in vivo. Model protein studies using FITC-labeled cytochrome C (FITC-CC) revealed efficient and high protein loading up to 17.2 wt% for CPRPs. FITC-CC-loaded CPRPs exhibited a small size of 82-90 nm, reduction-responsive protein release, as well as greatly enhanced internalization and cytoplasmic protein release in A549 lung cancer cells compared with the non-targeted FITC-CC-loaded RPs control. GrB-loaded CPRPs showed a high potency toward A549 lung cancer cells with a half maximal inhibitory concentration (IC50) of 20.7 nM. Under the same condition, free GrB was essentially non-toxic. Importantly, installing cell-selective penetrating peptide did not alter the circulation time but did enhance tumor accumulation of RPs. Orthotopic A549-Luc lung tumor-bearing nude mice administered with GrB-loaded CPRPs at a dosage of 2.88 nmol GrB equiv./kg showed complete tumor growth inhibition with little body weight loss throughout the treatment period, resulting in significantly improved survival rate over the non-targeted and non-treated controls. These cell-selective penetrating and reduction-responsive polymersomes provide a targeted protein therapy for cancers.

Efficacious delivery of protein drugs to prostate cancer cells by PSMA-targeted pH-responsive chimaeric polymersomes.

Protein drugs as one of the most potent biotherapeutics have a tremendous potential in cancer therapy. Their application is, nevertheless, restricted by absence of efficacious, biocompatible, and cancer-targeting nanosystems. In this paper, we report that 2-[3-[5-amino-1-carboxypentyl]-ureido]-pentanedioic acid (Acupa)-decorated pH-responsive chimaeric polymersomes (Acupa-CPs) efficiently deliver therapeutic proteins into prostate cancer cells. Acupa-CPs had a unimodal distribution with average sizes ranging from 157-175 nm depending on amounts of Acupa. They displayed highly efficient loading of both model proteins, bovine serum albumin (BSA) and cytochrome C (CC), affording high protein loading contents of 9.1-24.5 wt.%. The in vitro release results showed that protein release was markedly accelerated at mildly acidic pH due to the hydrolysis of acetal bonds in the vesicular membrane. CLSM and MTT studies demonstrated that CC-loaded Acupa10-CPs mediated efficient delivery of protein drugs into PSMA positive LNCaP cells leading to pronounced antitumor effect, in contrast to their non-targeting counterparts and free CC. Remarkably, granzyme B (GrB)-loaded Acupa10-CPs caused effective apoptosis of LNCaP cells with a low half-maximal inhibitory concentration (IC50) of 1.6 nM. Flow cytometry and CLSM studies using MitoCapture™ revealed obvious depletion of mitochondria membrane potential in LNCaP cells treated with GrB-loaded Acupa10-CPs. The preliminary in vivo experiments showed that Acupa-CPs had a long circulation time with an elimination phase half-life of 3.3h in nude mice. PSMA-targeted, pH-responsive, and chimaeric polymersomes have appeared as efficient protein nanocarriers for targeted prostate cancer therapy.

Galactose-installed photo-crosslinked pH-sensitive degradable micelles for active targeting chemotherapy of hepatocellular carcinoma in mice.

In this study, we designed and developed galactose-installed photo-crosslinked pH-sensitive degradable micelles (Gal-CLMs) for active targeting chemotherapy of hepatocellular carcinoma in mice. Gal-CLMs were readily obtained from co-self-assembly of poly(ethylene glycol)-b-poly(mono-2,4,6-trimethoxy benzylidene-pentaerythritol carbonate-co-acryloyl carbonate) (PEG-b-P(TMBPEC-co-AC)) and Gal-PEG-b-poly(ε-caprolactone) (Gal-PEG-b-PCL) copolymers followed by photo-crosslinking. Notably, paclitaxel (PTX)-loaded Gal-CLMs (Gal-PTX-CLMs) showed a narrow distribution (PDI=0.08-0.12) with average sizes ranging from 92.1 to 136.3nm depending on the Gal contents. The release of PTX from Gal-CLMs while inhibited at physiological pH was enhanced under endosomal pH conditions. MTT assays in asialoglycoprotein receptor (ASGP-R) over-expressing HepG2 cells demonstrated that half-maximal inhibitory concentration (IC50) values of Gal-PTX-CLMs decreased from 11.7 to 2.9 to 1.1µg/mL with increasing Gal contents from 10% to 20% to 30%, supporting receptor-mediated endocytosis mechanism. The in vivo biodistribution studies in human hepatoma SMMC-7721 tumor-bearing nude mice displayed that Gal20-PTX-CLMs resulted in significantly enhanced drug accumulation in the tumors over non-targeting PTX-CLM counterpart. In accordance, Gal20-PTX-CLMs caused much greater tumor growth inhibition than non-targeting PTX-CLMs as well as non-crosslinking Gal20-PTX-NCLM controls (average tumor volume: ca. 35mm(3)versus 144mm(3) and 130mm(3), respectively). Histological analysis showed that Gal20-PTX-CLMs induced more extensive apoptosis of tumor cells while less damage to normal liver and kidney compared to Taxol. Ligand-installed photo-crosslinked pH-responsive degradable micelles have a great potential for targeted cancer chemotherapy.