Investigation of Dual-Loaded Doxorubicin and Sorafenib Liposomes Co-Modified with Glycyrrhetinic Acid and Cell-Penetrating Peptide TAT.

BACKGROUND: Combining Doxorubicin (DOX) with sorafenib (SF) is a promising strategy for treating Hepatocellular Carcinoma (HCC). However, strict dosage control is required for both drugs, and there is a lack of target selectivity. OBJECTIVE: This study aims to develop a novel nano-drug delivery system for the combined use of DOX and SF, aiming to reduce their respective dosages, enhance therapeutic efficacy, and improve target selectivity. METHODS: DOX/SF co-loaded liposomes (LPs) were prepared using the thin-film hydration method. The liposomes were modified with 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine (DSPE)- polyethylene glycol (PEG2000), DSPE-PEG1000-cell penetrating peptide TAT, and Glycyrrhetinic Acid (GA). The basic properties of the liposomes were characterized. CCK-8 cell viability assays were conducted using HepG2, MHCC97-H, and PLC cell models, and apoptosis experiments were performed using HepG2 cells to determine if this delivery system could reduce the respective dosages of DOX and SF and enhance HCC cytotoxicity. Liposome uptake experiments were performed using HepG2 cells to validate the target selectivity of this delivery system. RESULTS: A GA/TAT-DOX/SF-LP liposomal nano drug delivery system was successfully constructed, with a particle size of 150 nm, a zeta potential of -7.9 mV, a DOX encapsulation efficiency of 92%, and an SF encapsulation efficiency of 88.7%. Cellular experiments demonstrated that this delivery system reduced the required dosages of DOX and SF, exhibited stronger cytotoxicity against liver cancer cells, and showed better target selectivity. CONCLUSION: A simple and referenceable liposomal nano drug delivery system has been developed for the combined application of DOX and SF in hepatocellular carcinoma treatment.

Preparation of double-loaded bitter ginseng derivative B21-DOX liposomes co-modified with SP94 and BR2 ligand and its in vitro anti-hepatocarcinogenic effect.

AIM: To construct a novel liposomal drug delivery system co-modified with SP94 and BR2 ligands, encapsulating both the bitter ginseng derivative B21 and doxorubicin (DOX), to achieve superior anti-tumour efficacy and reduced toxic side effects. METHODS: Liposomes were prepared using an organic phase reaction method, with B21 encapsulated in the lipid phase and DOX in the aqueous phase. The liposomes were further modified with SP94 and BR2 peptides. The characterisations, cytotoxicity, and in vitro targeting effects were assessed through various methods including ultraviolet spectrophotometry, high-performance liquid chromatography, nano-size analysis, ultrafiltration centrifugation, dialysis, transmission electron microscopy, flow cytometry, Methylthiazolyldiphenyl-tetrazolium bromide assay, confocal laser scanning microscopy, transwell assay, and tumorsphere assay. RESULTS: SP94/BR2-B21/DOX-LP liposomes were spherical with an average diameter of 120.87 ± 1.00 nm, a polydispersity index (PDI) of 0.223 ± 0.006, and a surface charge of -23.1 ± 1.27 mV. The encapsulation efficiencies for B21 and DOX were greater than 85% and 97% (mg/mg), respectively. The results indicated that SP94/BR2-B21/DOX-LP exhibited enhanced targeting and cytotoxicity compared to single-ligand modified and unmodified liposomes, with the combined encapsulation of B21 and DOX showing synergistic anti-hepatocarcinogenic effects. CONCLUSION: SP94/BR2-B21/DOX-LP liposomes represent a promising targeted drug delivery system for hepatocellular carcinoma, offering improved membrane penetration, enhanced therapeutic efficacy, and reduced systemic toxicity.

Dual-targeting liposomes modified with BTP-7 and pHA for combined delivery of TCPP and TMZ to enhance the anti-tumour effect in glioblastoma cells.

AIM: To construct a novel nano-carrier with dual ligands to achieve superior anti-tumour efficacy and lower toxic side effects. METHODS: Liposomes were prepared by thin film hydration method. Ultraviolet, high performance liquid chromatography, nano-size analyser, ultrafiltration centrifugation, dialysis, transmission electron microscope, flow cytometry, Cell Counting Kit-8, confocal laser scanning microscopy, transwell, and tumorsphere assay were used to study the characterisations, cytotoxicity, and in vitro targeting of dg-Bcan targeting peptide (BTP-7)/pHA-temozolomide (TMZ)/tetra(4-carboxyphenyl)porphyrin (TCPP)-Lip. RESULTS: BTP-7/pHA-TMZ/TCPP-Lip was a spheroid with a mean diameters of 143 ± 3.214 nm, a polydispersity index of 0.203 ± 0.025 and a surface charge of -22.8 ± 0.425 mV. The drug loadings (TMZ and TCPP) are 7.40 ± 0.23% and 2.05 ± 0.03% (mg/mg); and the encapsulation efficiencies are 81.43 ± 0.51% and 84.28 ± 1.64% (mg/mg). The results showed that BTP-7/pHA-TMZ/TCPP-Lip presented enhanced targeting and cytotoxicity. CONCLUSION: BTP-7/pHA-TMZ/TCPP-Lip can specifically target the tumour cells to achieve efficient drug delivery, and improve the anti-tumour efficacy and reduces the systemic toxicity.

Advances in liposomes loaded with photoresponse materials for cancer therapy.

Cancer treatment is presently a significant challenge in the medical domain, wherein the primary modalities of intervention include chemotherapy, radiation therapy and surgery. However, these therapeutic modalities carry side effects. Photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as promising modalities for the treatment of tumors in recent years. Phototherapy is a therapeutic approach that involves the exposure of materials to specific wavelengths of light, which can subsequently be converted into either heat or Reactive Oxygen Species (ROS) to effectively eradicate cancer cells. Due to the hydrophobicity and lack of targeting of many photoresponsive materials, the use of nano-carriers for their transportation has been extensively explored. Among these nanocarriers, liposomes have been identified as an effective drug delivery system due to their controllability and availability in the biomedical field. By binding photoresponsive materials to liposomes, it is possible to reduce the cytotoxicity of the material and regulate drug release and accumulation at the tumor site. This article provides a comprehensive review of the progress made in cancer therapy using photoresponsive materials loaded onto liposomes. Additionally, the article discusses the potential synergistic treatment through the combination of phototherapy with chemo/immuno/gene therapy using liposomes.

QSAR prediction, synthesis, anticancer evaluation, and mechanistic investigations of novel sophoridine derivatives as topoisomerase I inhibitors.

Sophoridine, which is derived from the Leguminous plant Sophora alopecuroides L., has certain pharmacological activity as a new anticancer drug. Herein, a series of novel N-substituted sophoridine derivatives was designed, synthesized and evaluated with anticancer activity. Through QSAR prediction models, it was discovered that the introduction of a benzene ring as a main pharmacophore and reintroduced into a benzene in para position on the phenyl ring in the novel sophoridine derivatives improved the anticancer activity effectively. In vitro, 28 novel compounds were evaluated for anticancer activity against four human tumor cell lines (A549, CNE-2, HepG-2, and HEC-1-B). In particular, Compound 26 exhibited remarkable inhibitory effects, with an IC50 value of 15.6 µM against HepG-2 cells, surpassing cis-Dichlorodiamineplatinum (II). Molecular docking studies verified that the derivatives exhibit stronger binding affinity with DNA topoisomerase I compared to sophoridine. In addition, 26 demonstrated significant inhibition of DNA Topoisomerase I and could arrest cells in G0/G1 phase. This study provides valuable insights into the design and synthesis of N-substituted sophoridine derivatives with anticancer activity.

Laser-Ignited Lipid Peroxidation Nanoamplifiers for Strengthening Tumor Photodynamic Therapy Through Aggravating Ferroptotic Propagation and Sustainable High Immunogenicity.

Photodynamic therapy (PDT) is extensively investigated for tumor therapy in the clinic. However, the efficacy of PDT is severely limited by the tissue penetrability of light, short effective half-life and radius of reactive oxygen species (ROS), and the weak immunostimulatory effect. In this study, a glutathione (GSH)-activatable nano-photosensitizer is developed to load with arachidonic acid (AA) and camouflage by erythrocyte membrane, which serves as a laser-ignited lipid peroxidation nanoamplifier (MAR). The photosensitive effect of MAR is recovered accompanied by the degradation in the tumor microenvironment and triggers the peroxidation of AA upon laser excitation. Interestingly, it aggravates the propagation of ferroptosis among cancer cells by driving the continuous lipid peroxidation chain reactions with the participation of the degradation products, ferrous ions (Fe2+), and AA. Consequently, even the deep-seated tumor cells without illumination also undergo ferroptosis owing to the propagation of ferroptotic signal. Moreover, the residual tumor cells undergoing ferroptosis still maintain high immunogenicity after PDT, thus continuously triggering sufficient tumor-associated antigens (TAAs) release to remarkably promote the anti-tumor immune response. Therefore, this study will provide a novel "all-in-one" nano-photosensitizer that not only amplifies the damaging effect and expands the effective range of PDT but also improves the immunostimulatory effect after PDT.

Preparation and cytotoxicity evaluation of folic acid-modified YF8-OA self-assembled lipid prodrug nanoparticles.

This study aimed to improve the use of YF8, a matrine derivative obtained through chemical transformation of matrine extracted from Sophora alopecuroides. YF8 has demonstrated improved cytotoxicity compared to matrine, but its hydrophobic nature hinders its application. To overcome this, the lipid prodrug YF8-OA was synthesized by linking oleic acid (OA) to YF8 through an ester bond. Although YF8-OA could self-assemble into unique nanostructures in water, it was not sufficiently stable. To enhance the stability of YF8-OA lipid prodrug nanoparticles (LPs), we employed the strategy of PEGylation using DSPE-mPEG2000 or DSPE-mPEG2000 conjugated with folic acid (FA). This resulted in the formation of uniform spherical nanoparticles with greatly improved stability and a maximum drug load capacity upto 58.63%. Cytotoxicity was evaluated in A549, HeLa, and HepG2 cell lines. The results showed that in HeLa cells, the IC50 value of YF8-OA/LPs with FA-modified PEGylation was significantly lower than that of YF8-OA/LPs modified by PEGylation alone. However, no significant enhancement was observed in A549 and HepG2 cells. In conclusion, the lipid prodrug YF8-OA can form nanoparticles in aqueous solution to address its poor water solubility. Modification with FA resulted in further enhanced cytotoxicity, providing a potential avenue for exerting the antitumor activity of matrine analogs.

Knockdown of TTC9 inhibits the proliferation, migration and invasion, but induces the apoptosis of lung adenocarcinoma cells.

Lung adenocarcinoma (LUAD) is one of the most commonly diagnosed subtypes of lung cancer, and one of the deadliest cancers. Tetratricopeptide repeat domain 9A (TTC9) is upregulated and has played an oncogenic role in some malignant tumors. However, the expression and role of TTC9 has not yet been elucidated in LUAD. Here, we investigated the expression profiles, biological functions and potential molecular mechanism of the TTC9 gene in LUAD. TTC9 expression was significantly overexpressed in LUAD tissues compared with that in normal lung tissues. TTC9 expression was closely correlated with gender, lymph node metastasis, and survival status in the TCGA-LUAD cohort. Subsequent cellular function assays demonstrated that knockdown of TTC9 promoted PC9 cell apoptosis and inhibited cell proliferation, migration and invasion, leading to cell cycle arrest in G2 phase. Moreover, inhibition of TTC9 suppressed the tumorigenicity of PC9 cells in nude mice. TTC9 might serve as oncogene in LUAD through cancer-related signaling pathways including p38 MAPK pathway. The expression of TTC9 gene might be modulated by DNA copy number variant and DNA methylation. TTC9 was significantly associated with tumor immune infiltration patterns. Accordingly, TTC9 may be a novel therapeutic target for the treatment of LUAD.

Overexpression of ERCC6L correlates with poor prognosis and confers malignant phenotypes of lung adenocarcinoma.

Excision repair cross­complementation group 6 like (ERCC6L) has been reported to be upregulated in a variety of malignant tumors and plays a critical oncogenic role. However, the role and molecular mechanism of ERCC6L in lung adenocarcinoma (LUAD) remain unclear, and were therefore investigated in the present study. Clinical data of patients with LUAD were obtained and bioinformatics analysis was performed to investigate the expression characteristics, prognostic value, and biological function of ERCC6L. In addition, cell function experiments were performed to detect the effect of ERCC6L silencing on the biological behavior of LUAD cells. The results revealed that ERCC6L expression was significantly higher in LUAD tissues vs. normal lung tissues and closely associated with nodal invasion, advanced clinical stage and survival in LUAD. Overexpression of ERCC6L was an independent prognostic biomarker of overall survival, progression­free interval, and disease­specific survival in patients with LUAD. DNA amplification and low methylation levels of ERCC6L suggested regulation at both the genetic and epigenetic levels. The most significant positive genes co­expressed with ERCC6L were mainly enriched in the cell cycle signaling pathway. The major functions of ERCC6L in LUAD cells were positively correlated with the cell cycle, DNA damage, DNA repair, proliferation, invasion and epithelial­mesenchymal transition (EMT). Knockdown of ERCC6L inhibited the proliferative, migratory and invasive abilities of A549 and PC9 cells. It also promoted cell apoptosis, and led to cell cycle arrest in the S phase. ERCC6L may regulate the EMT process through the Wnt/ß­catenin and Wnt/Notch 3 signaling pathways, thus regulating the tumorigenesis and progression of LUAD. The overexpression of ERCC6L may be a biological indicator for the diagnosis and prognosis of LUAD. ERCC6L may be a novel molecular target for the treatment of lung cancer.

Synergistic Combination of Doxorubicin and Paclitaxel Delivered by Blood Brain Barrier and Glioma Cells Dual Targeting Liposomes for Chemotherapy of Brain Glioma.

Brain glioma has become a great threat to human health in decades. To maximize the therapeutic efficacy of brain glioma as well as minimize the side effects, drugs should be penetrated through the blood brain barrier (BBB) and then targeted to the brain carcinoma cells with effective concentration. A dual-ligand delivery strategy was employed to achieve both of these goals. Herein, both specific targeting ligand transferrin and cell-penetrating peptide TAT were conjugated onto liposomes (TF/TAT-LP) to develop a brain glioma dual-ligand delivery system. Synergistic combination of doxorubicin (DOX) and paclitaxel (PTX), compared with using them separately, could more efficiently suppress tumor aggravation. In vitro studies including cellular uptake and three-dimensional (3D) tumor spheroid penetration assays proved that TF/TAT-LP could target brain endothelial and carcinoma cells with deeply penetration through the endothelial monolayers and target to the core of the tumor spheroids. In vivo imaging proved that the TF/TAT-LP possesses the highest tumor distribution, which was also confirmed by fluorescent images of the brain section. Ultimately, the DOX and PTX-loaded TF/TAT-LP (TF/TAT-PTX/DOX-LP) shows the best anti-glioma effect with improvement of glioma bearing survival time. In conclusion, synergistic combination of doxorubicin and paclitaxel delivered by the TF/TAT-LP could efficiently target to the brain glioma with satisfying treatment efficiency, which may be a promising formulation for glioma therapy.

Targeted delivery of transferrin and TAT co-modified liposomes encapsulating both paclitaxel and doxorubicin for melanoma.

The purpose of this study was to develop an efficient dual-ligand based liposomal drug delivery system with targeting specificity as well as properties that would kill melanoma cells. Liposomes modified with transferrin (Tf) and cell-penetrating peptide TAT was prepared, which encapsulated two kinds of chemotherapy drugs, paclitaxel and doxorubicin (Tf/TAT-PTX/DOX-LP). The Tf ligands specifically bind to the overexpressed Tf receptors on the surface of melanoma cells, while the TAT ligands functioned as a classical cell penetrating peptide, helping dual-ligand liposomes be internalized by melanoma cells. The effect of dual-targeting system and "double-drug" combination therapy were evaluated both in vitro and in vivo. In vitro, cellular uptake, intracellular distribution and tumor spheroids penetration studies demonstrated that the system could not only be selectively and efficiently penetrate melanoma cells. Besides, apoptosis staining assay and cytotoxicity showed effective anti-tumor capability and obvious synergistic effect of combination therapy of PTX and DOX. In vivo imaging and fluorescent images of tumor section further demonstrated that Tf/TAT-PTX/DOX-LP had the highest tumor distribution. The results of these experiments demonstrated that double-drug liposomal drug delivery systems (DDS) had both enhanced targeting efficiency and increased therapeutic efficacy.

Tumor microenvironment sensitive doxorubicin delivery and release to glioma using angiopep-2 decorated gold nanoparticles.

Glioma is still hard to be treated due to their complex microenvironment. In this study, a gold nanoparticle-based delivery system was developed. The system, An-PEG-DOX-AuNPs, was loaded with doxorubicin (DOX) through hydrazone, an acid-responsive linker, and was functionalized with angiopep-2, a specific ligand of low density lipoprotein receptor-related protein-1 (LRP1), which could mediate the system to penetrate blood brain barrier and target to glioma cells. The particle size of An-PEG-DOX-AuNPs was 39.9 nm with a zeta potential of -19.3 mV, while the DOX loading capacity was 9.7%. In vitro, the release of DOX from DOX-AuNPs was pH-dependent. At lower pH values, especially 5.0 and 6.0, release of DOX was much quicker than that at pH 6.8 and 7.4. After coating with PEG, the acid-responsive release of DOX from PEG-DOX-AuNPs was almost the same as that from DOX-AuNPs. Cellular uptake study showed obviously higher intensity of intracellular An-PEG-DOX-AuNPs compared with PEG-DOX-AuNPs. In vivo, An-PEG-DOX-AuNPs could distribute into glioma at a higher intensity than that of PEG-DOX-AuNPs and free DOX. Correspondingly, glioma-bearing mice treated with An-PEG-DOX-AuNPs displayed the longest median survival time, which was 2.89-fold longer than that of saline. In conclusion, An-PEG-DOX-AuNPs could specifically deliver and release DOX in glioma and significantly expand the median survival time of glioma-bearing mice.

Increased delivery of doxorubicin into tumor cells using extracellularly activated TAT functionalized liposomes: in vitro and in vivo study.

The development of highly efficient tumor-targeted delivery systems is crucial for successful tumor treatment. Previously, a novel cell-penetrating peptide TAT and cleavable polyethylene glycol (PEG) co-modified liposome delivery system (C-TAT-Lipo) showed enhanced accumulation in tumor regions. Under the control of cysteine (Cys), the liposomes were activated extracellularly and achieved increased delivery of their cargo into tumor cells efficiently. In this study, we developed an optimal formulation for the encapsulation of Doxorubicin (DOX) by this delivery system for tumor treatment. The in vitro study showed that the C-TAT-Lipo with Cys delivery system not only enhanced the amount of DOX delivered by at least 100% compared to other DOX-containing formulations, but also displayed high cytotoxicity against tumorigenic cell lines. Compared to other groups, the DOX-loaded C-TAT-Lipo formulation in the presence of cysteine enhanced treatment efficacy by lowering the IC50 (1.67 +/- 0.14 microM) and increasing the cancer cell apoptosis percentage (37.10%). Moreover, the in vivo antitumor activity also showed that DOX-loaded C-TAT-Lipo with injection of cysteine achieved the best tumor growth inhibition with a tumor growth rate of only 58.40 +/- 16.33% (% of initial volume/day), which was significant less than that achieved by other DOX formulations.

A pH-responsive α-helical cell penetrating peptide-mediated liposomal delivery system.

Tumor-oriented nanocarrier drug delivery approaches with pH-sensitivity have been drawing considerable attentions over the years. Here we described a liposomal delivery system modified with pH-responsive cell penetrating peptide TH (TH-Lip). Conventional cell penetrating peptide (CPP)-related drug delivery tactics sometimes seemed limited due to the extensive in vivo penetration and the lack of proper selectivity of conventional CPPs. In this study, TH (AGYLLGHINLHHLAHL(Aib)HHIL-NH2), an engineered α-helical cell penetrating peptide originated from peptide TK (AGYLLGKINLKKLAKL(Aib)LLIL-NH2), was endowed pH-responsiveness after complete replacement of all lysines in the sequence of TK into histidines, and was introduced onto the surface of liposomes. Accordingly, TH-Lip could benefit from the unique property of TH, as the cell penetrating capacity of TH was concealed during the blood circulation and in normal tissues because of the neutral pH under those conditions. However, when TH-Lip reached the tumor, and as pH declined, histidines in TH peptide protonated and the surface charge of TH-Lip converted from negative to positive, initiating activated cell penetrating capacity and leading to enhanced cellular and tumor spheroid uptake. The endocytosis inhibition assay demonstrated that the endocytosis of TH-Lip was influenced by the positively charged surface of the liposomes in acidic environment and was mediated by clathrin, and the intracellular trafficking study suggested that the liposomes were mainly accumulated in endoplasmic reticulum and Golgi apparatus. After systemic administration in mice, TH-Lip could be internalized into tumor cells efficaciously. When it comes to the delivery of paclitaxel (PTX), the pH-responsiveness of TH-Lip led to strong inhibition against tumor cell growth which occurred both in vitro (under pH 6.3) and in vivo, and the tumor inhibition rate reached 86.3% on C26 tumor-bearing mice for PTX-loaded TH-Lip. Therefore, TH-Lip proved itself to be a promising pH-responsive strategy for drug delivery within acidified tumor microenvironment.

Targeted delivery of cargoes into a murine solid tumor by a cell-penetrating peptide and cleavable poly(ethylene glycol) comodified liposomal delivery system via systemic administration.

A liposomal delivery system with a high efficiency of accumulation in tumor tissue and then transportation of the cargo into tumor cells was developed here and evaluated via systemic administration. 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)(2000) (DSPE-PEG(2000))-TAT and protective DSPE-PEG(2000) modified liposomes possessing good stability in 50% FBS (fetal bovine serum) and good uptake efficiency were used as the basic formulation (TAT-SL; SL = stealth liposome), and then longer cysteine (Cys)-cleavable PEG(5000) was incorporated to modulate the function of TAT. All of the formulations to be used in vivo had sizes in a range of 80-100 nm and were stable in the presence of 50% FBS. Optical imaging showed that the incorporation of cleavable PEG(5000) into TAT-SL (i.e., C-TAT-SL) led to much more tumor accumulation and much less liver distribution compared with TAT-SL. The in vivo delivery profiles of C-TAT-SL were investigated using DiD as a fluorescent probe. Confocal laser scanning microscopy and flow cytometry showed that C-TAT-SL had a 48% higher (p < 0.001) delivery efficiency in the absence of Cys and a 130% higher (p < 0.001) delivery efficiency in the presence of Cys than the control (SL), indicating the successful targeted delivery of cargo was achieved by C-TAT-SL via systemic administration especially with a subsequent administration of Cys.

Efficient delivery of payload into tumor cells in a controlled manner by TAT and thiolytic cleavable PEG co-modified liposomes.

Recently, PEGylation has been extensively employed to increase the circulation time of liposomes and enhance their accumulation in tumor tissue via the enhanced permeability and retention (EPR) effect; however, poly(ethylene glycol) (PEG) is unfavorable for the uptake of liposomes by tumor cells because of its steric hindrance. In this study, thiolytic cleavable PEG modified liposomes were used to solve this dilemma. Before arrival at the tumor tissue, PEG presents on the surface of liposomes, which is useful for passive accumulation in tumor tissue. Upon reaching the tumor tissues, the PEG chain could be removed by a safe cleaving reagent l-cysteine (l-Cys), and thus, the steric hindrance of PEG could be overcome conveniently. To further improve the uptake of liposomes, a "functional molecule" cell-penetrating peptide TAT was attached to the distal end of a shorter PEG spacer anchored to the surface of the liposomes, which could be shielded by cleavable PEG during circulation; upon arriving at tumor tissue, PEG was removed and thus the "functional molecule" TAT was exposed, and then TAT could mediate the uptake of the liposomes with high efficiency. In this study, thiolytic cleavable PEG was synthesized via a disulfide bridge, DOPE-PEG(1600)-TAT was synthesized by sulfhydryl-maleimide reaction, and then Rh-PE labeled liposomes composed of 2% DOPE-PEG(1600)-TAT and various amounts of cleavable PEG(5000) (2%, 4%, and 8%) were prepared, with particle size around 100 nm and slightly negative charge. These liposomes showed good stability in the presence of 10% serum. Their uptake by tumor cells HepG2 in vitro was assessed qualitatively and quantitatively. Liposomes modified with 2% DOPE-PEG(1600)-TAT and 8% DOPE-S-S-mPEG(5000) were regarded as the optimal formulation. In this preparation, nearly no uptake could be observed before addition of l-Cys, which meant undesired uptake during circulation could be avoided, while the uptake upon addition of l-Cys was 4 times as high as that in the absence of l-Cys. For the uptake in vivo, calcein loaded and Rh-PE labeled 8% cleavable PEG + 2% TAT modified liposomes were injected intratumorally into H22 tumor bearing mice. Confocal laser scanning microscopy (CLSM) showed that the uptake of 8% cleavable PEG + 2% TAT modified liposomes was much higher than that of 8% noncleavable PEG + 2% TAT modified liposomes in the presence of l-Cys. Thus, tumor targeted delivery could be achieved efficiently by the liposomal drug delivery system developed here in a controlled manner.