Specific tumor delivery of paclitaxel using glycolipid-like polymer micelles containing gold nanospheres

Optimized DOX Drug Deliveries via Chitosan-Mediated Nanoparticles and Stimuli Responses in Cancer Chemotherapy: A Review

Chitosan nanoparticles (NPs) serve as useful multidrug delivery carriers in cancer chemotherapy. Chitosan has considerable potential in drug delivery systems (DDSs) for targeting tumor cells. Doxorubicin (DOX) has limited application due to its resistance and lack of specificity. Chitosan NPs have been used for DOX delivery because of their biocompatibility, biodegradability, drug encapsulation efficiency, and target specificity. In this review, various types of chitosan derivatives are discussed in DDSs to enhance the effectiveness of cancer treatments. Modified chitosan-DOX NP drug deliveries with other compounds also increase the penetration and efficiency of DOX against tumor cells. We also highlight the endogenous stimuli (pH, redox, enzyme) and exogenous stimuli (light, magnetic, ultrasound), and their positive effect on DOX drug delivery via chitosan NPs. Our study sheds light on the importance of chitosan NPs for DOX drug delivery in cancer treatment and may inspire the development of more effective approaches for cancer chemotherapy.

Nano-Based Drug Delivery Systems: Potential Developments in the Therapy of Metastatic Osteosarcoma-A Narrative Review

Osteosarcoma, a predominant malignant bone tumor, poses significant challenges due to its high metastatic and recurrent nature. Although various therapeutic strategies are currently in use, they often inadequately target osteosarcoma metastasis. This review focuses on the potential of nanoscale drug delivery systems to bridge this clinical gap. It begins with an overview of the molecular mechanisms underlying metastatic osteosarcoma, highlighting the limitations of existing treatments. The review then transitions to an in-depth examination of nanoscale drug delivery technologies, emphasizing their potential to enhance drug bioavailability and reduce systemic toxicity. Central to this review is a discussion of recent advancements in utilizing nanotechnology for the potential intervention of metastatic osteosarcoma, with a critical analysis of several preclinical studies. This review aims to provide insights into the potential applications of nanotechnology in metastatic osteosarcoma therapy, setting the stage for future clinical breakthroughs and innovative cancer treatments.

Chitosan-based nanoscale systems for doxorubicin delivery: Exploring biomedical application in cancer therapy

Green chemistry has been a growing multidisciplinary field in recent years showing great promise in biomedical applications, especially for cancer therapy. Chitosan (CS) is an abundant biopolymer derived from chitin and is present in insects and fungi. This polysaccharide has favorable characteristics, including biocompatibility, biodegradability, and ease of modification by enzymes and chemicals. CS-based nanoparticles (CS-NPs) have shown potential in the treatment of cancer and other diseases, affording targeted delivery and overcoming drug resistance. The current review emphasizes on the application of CS-NPs for the delivery of a chemotherapeutic agent, doxorubicin (DOX), in cancer therapy as they promote internalization of DOX in cancer cells and prevent the activity of P-glycoprotein (P-gp) to reverse drug resistance. These nanoarchitectures can provide co-delivery of DOX with antitumor agents such as curcumin and cisplatin to induce synergistic cancer therapy. Furthermore, co-loading of DOX with siRNA, shRNA, and miRNA can suppress tumor progression and provide chemosensitivity. Various nanostructures, including lipid-, carbon-, polymeric- and metal-based nanoparticles, are modifiable with CS for DOX delivery, while functionalization of CS-NPs with ligands such as hyaluronic acid promotes selectivity toward tumor cells and prevents DOX resistance. The CS-NPs demonstrate high encapsulation efficiency and due to protonation of amine groups of CS, pH-sensitive release of DOX can occur. Furthermore, redox- and light-responsive CS-NPs have been prepared for DOX delivery in cancer treatment. Leveraging these characteristics and in view of the biocompatibility of CS-NPs, we expect to soon see significant progress towards clinical translation.

Protein-Protein Interaction Inhibitors Targeting the Eph-Ephrin System with a Focus on Amino Acid Conjugates of Bile Acids

The role of the Eph-ephrin system in the etiology of pathological conditions has been consolidated throughout the years. In this context, approaches directed against this signaling system, intended to modulate its activity, can be strategic therapeutic opportunities. Currently, the most promising class of compounds able to interfere with the Eph receptor-ephrin protein interaction is composed of synthetic derivatives of bile acids. In the present review, we summarize the progresses achieved, in terms of chemical expansions and structure-activity relationships, both in the steroidal core and the terminal carboxylic acid group, along with the pharmacological characterization for the most promising Eph-ephrin antagonists in in vivo settings.

Traditional herbal medicine and nanomedicine: Converging disciplines to improve therapeutic efficacy and human health

Traditional herbal medicine (THM), an ancient science, is a gift from nature. For thousands of years, it has helped humans fight diseases and protect life, health, and reproduction. Nanomedicine, a newer discipline has evolved from exploitation of the unique nanoscale morphology and is widely used in diagnosis, imaging, drug delivery, and other biomedical fields. Although THM and nanomedicine differ greatly in time span and discipline dimensions, they are closely related and are even evolving toward integration and convergence. This review begins with the history and latest research progress of THM and nanomedicine, expounding their respective developmental trajectory. It then discusses the overlapping connectivity and relevance of the two fields, including nanoaggregates generated in herbal medicine decoctions, the application of nanotechnology in the delivery and treatment of natural active ingredients, and the influence of physiological regulatory capability of THM on the in vivo fate of nanoparticles. Finally, future development trends, challenges, and research directions are discussed.

Regulating immune memory and reversing tumor thermotolerance through a step-by-step starving-photothermal therapy

Background

Photothermal therapy (PTT) is a highly effective treatment for solid tumors and can induce long-term immune memory worked like an in situ vaccine. Nevertheless, PTT inevitably encounters photothermal resistance of tumor cells, which hinders therapeutic effect or even leads to tumor recurrence. Naïve CD8+ T cells are mainly metabolized by oxidative phosphorylation (OXPHOS), followed by aerobic glycolysis after activation. And the differentiate of effector CD8+ T cell (CD8+ T_eff) into central memory CD8+ T cell (CD8+ TCM) depends on fatty acid oxidation (FAO) to meet their metabolic requirements, which is regulated by adenosine monophosphate activated protein kinase (AMPK). In addition, the tumor microenvironment (TME) is severely immunosuppressive, conferring additional protection against the host immune response mediated by PTT.

Methods

Metformin (Met) down-regulates NADH/NADPH, promotes the FAO of CD8+ T cells by activating AMPK, increases the number of CD8+ TCM, which boosts the long-term immune memory of tumor-bearing mice treated with PTT. Here, a kind of PLGA microspheres co-encapsulated hollow gold nanoshells and Met (HAuNS-Met@MS) was constructed to inhibit the tumor progress. 2-Deoxyglucose (2DG), a glycolysis inhibitor for cancer starving therapy, can cause energy loss of tumor cells, reduce the heat stress response of tumor cell, and reverse its photothermal resistance. Moreover, 2DG prevents N-glycosylation of proteins that cause endoplasmic reticulum stress (ERS), further synergistically enhance PTT-induced tumor immunogenic cell death (ICD), and improve the effect of immunotherapy. So 2DG was also introduced and optimized here to solve the metabolic competition among tumor cells and immune cells in the TME.

Results

We utilized mild PTT effect of HAuNS to propose an in situ vaccine strategy based on the tumor itself. By targeting the metabolism of TME with different administration strategy of 2DG and perdurable action of Met, the thermotolerance of tumor cells was reversed, more CD8+ TCMs were produced and more effective anti-tumor was presented in this study.

Conclusion

The Step-by-Step starving-photothermal therapy could not only reverse the tumor thermotolerance, but also enhance the ICD and produce more CD8+ TCM during the treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01011-2.

Structural control and biomedical applications of plasmonic hollow gold nanospheres: A mini review

Hollow gold nanospheres (HGNs) are core/shell structures with a dielectric material core, usually composed of solvent, and a gold metal shell. Such structures have two metal/dielectric interfaces to allow interaction between the gold metal with the interior and external dielectric environment. Upon illumination by light, HGNs exhibit unique surface plasmon resonance (SPR) properties compared to solid gold nanoparticles. Their SPR absorption/scattering can be tuned by changing their diameter, shell thicknesses, and surface morphologies. In addition to the low toxicity, easy functionalization, resistance to photobleaching, and sensitivity to changes in surrounding medium of gold, the enhanced surface-to-volume ratio and tunable SPR of HGNs make them highly attractive for different applications in the fields of sensing, therapy, and theranostics. In this article, we review recent progress on the synthesis and structural control of HGNs and applications of their SPR properties in biomedical sensing and theranostics. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > in vitro Nanoparticle-Based Sensing Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

Gold nanoparticle‑mediated delivery of paclitaxel and nucleic acids for cancer therapy (Review)

Paclitaxel is a potent antineoplastic agent, but poor solubility and resistance have limited its use. Gold nanoparticles (AuNPs) are widely studied as drug carriers because they can be engineered to prevent drug insolubility, carry nucleic acid payloads for gene therapy, target specific tumor cell lines, modulate drug release and amplify photothermal therapy. Consequently, the conjugation of paclitaxel with AuNPs to improve antiproliferative and pro‑apoptotic potency may enable improved clinical outcomes. There are currently a number of different AuNPs under development, including simple drug or nucleic acid carriers and targeted AuNPs that are designed to deliver therapeutic payloads to specific cells. The current study reviewed previous research on AuNPs and the development of AuNP‑based paclitaxel delivery.

Laser Immunotherapy in Combination with Perdurable PD-1 Blocking for the Treatment of Metastatic Tumors

A convenient and feasible therapeutic strategy for malignant and metastatic tumors was constructed here by combining photothermal ablation (PTA)-based laser immunotherapy with perdurable PD-1 blockade immunotherapy. Hollow gold nanoshells (HAuNS, a photothermal agent) and AUNP12 (an anti PD-1 peptide, APP) were co-encapsulated into poly(lactic- co-glycolic) acid (PLGA) nanoparticles. Unlike monoclonal PD-1/PD-L1 antibodies, PD-1 peptide inhibitor shows lower cost and immunotoxicity but needs frequent administration due to its rapid clearance in vivo. Our data here showed that the formed HAuNS- and APP-loaded PLGA nanoparticles (AA@PN) could maintain release periods of up to 40 days for the peptide, and a single intratumoral injection of AA@PN could replace the frequent administration of free APP. After the administration of AA@PN and irradiation with a near-infrared laser at the tumor site, an excellent killing effect on the primary tumor cells was achieved by the PTA. The nanoparticles also played a vaccine-like role under the adjuvant of cytosine-phospho-guanine (CpG) oligodeoxynucleotide and generated a localized antitumor-immune response. Furthermore, sustained APP release with laser-dependent transient triggering could induce the blockage of PD-1/PD-L1 pathway to activate T cells, thus subsequently generating a systemic immune response. Our data demonstrated that the PTA combined with perdurable PD-1 blocking could efficiently eradicate the primary tumors and inhibit the growth of metastatic tumors as well as their formation. The present study provides a promising therapeutic strategy for the treatment of advanced cancer with metastasis and presents a valuable reference for obtaining better outcomes in clinical cancer immunotherapy.

Suppress orthotopic colon cancer and its metastasis through exact targeting and highly selective drug release by a smart nanomicelle

The treatment of metastatic cancer is a huge challenge at the moment. Highly precise targeting delivery and drug release in tumor have always been our pursuit in cancer therapy, especially to advance cancer with metastasis, for increasing the efficacy and biosafety. We established a smart nanosized micelle, formed by tocopherol succinate (TOS) conjugated hyaluronic acid (HA) using a disulfide bond linker. The micelle (HA-SS-TOS, HSST) can highly specifically bind with CD44 receptor over-expressed tumor, and response selectively to high GSH level in the cells, inducing disulfide bond breakage and the release of the payload (paclitaxel, PTX). To predict the antitumor efficacy of the micelles more clinically, we established an orthotopic colon cancer model with high metastasis rate, which could be visualized by the luciferase bioluminescence. Our data confirmed CD44 high expression in the colon cancer cells. Highly matching between the micellar fluorescence and bioluminescence of cancer cells in intestines demonstrated an exact recognition of our micelles to orthotopic colon tumor and its metastatic cells, attributing to the mediation of CD44 receptors. Furthermore, the fluorescence of the released Nile Red from the micelles was found only in the tumor and its metastatic cells, and almost completely overlapped with the bioluminescence of the cancer cells, indicating a highly selective drug release. Our micelles presented an excellent therapeutic effect against metastatic colon cancer, and induced significantly prolonged survival time for the mice, which might become a promising nanomedicine platform for the future clinical application against advanced cancers with high CD44 receptor expression.

Effect of A-317491 delivered by glycolipid-like polymer micelles on endometriosis pain

Endometriosis is a common gynecological disease with a lack of effective clinical treatment. Current therapy often results in endometriosis pain recurrence and serious side effects. P2X₃ receptor, an adenosine triphosphate (ATP)-gated ion channel, might be implicated in endometriosis pain. In this study, chitosan oligosaccharide-g-stearic acid (CSOSA) polymer micelles-coated nanostructured lipid carriers (NLCs) were developed as a novel delivery system for A-317491, a selective P2X₃ receptor antagonist for endometriosis pain therapy. A-317491-loaded NLC (NLC/A-317491) could be coated by CSOSA micelles to form CSOSA/NLC/A-317491 nanoparticles. Pheochromocytoma PC12 cells, which highly expressed P2X₃ receptors, were used as a cell model, and the CSOSA/NLC/A-317491 partly blocked the Ca²⁺ influx induced by ATP stimulation. In nude mouse and rat endometriotic models, CSOSA/NLC could accumulate into endometriotic lesions after vein injection. In endometriotic rats, CSOSA/NLC/A-317491 reversed mechanical and heat hyperalgesia with long-term efficacy, which might be attributed to the massive CSOSA/NLC/A-317491 distribution in the endometriotic lesions. In conclusion, A-317491 delivered by CSOSA/NLC nanoparticles attenuated endometriosis pain in rats, and CSOSA/NLC/A-317491 could be used as an effective treatment strategy for P2X₃-targeted therapy in endometriosis pain.

Near infrared light mediated photochemotherapy for efficiently treating deep orthotopic tumors guided by ultrasound imaging

Recently, Combined cancer photothermal-chemotherapy has become a highly promising strategy in cancer treatment for its enhanced therapeutic efficacy, controlled drug release and reduced systemic toxicity. Almost all the reported strategies based on photothermal-chemotherapy have only focused on the treatment of superficial or subcutaneous cancer, which are not considered as a more clinically relevant and better predictive models of drug efficacy than orthotopic tumor models. Here, we reported an EphB4 receptor-targeting polymeric nanoplatform containing hollow gold nanospheres (HAuNS) and the anticancer drug paclitaxel (PTX) for cancer photothermal-chemotherapy. With the modification of the TNYL peptide, HP-TCS could specifically internalize into EphB4-positive SKOV3 and CT26 cells, further inducing the selective killing of the cells in co-cultured system, namely, EphB4-positive and EphB4-negative cells. Obvious targeting of the micelles into implanted orthotopic or subcutaneous tumors with high EphB4 expression was observed. Interestingly, increased accumulation of HP-TCS was observed in orthotopic colon tumors when compared with ectopic tumors. Highly specific accumulation of HP-TCS in EphB4-positive tumors significantly increased the feasibility of photothermal-chemotherapy mediated by the near infrared reflection (NIR) laser. Then, a systemic antitumor efficiency study was performed in implanted subcutaneous and visual orthotopic tumor models. Precise NIR laser irradiation could be localized on tumors under the guidance of B-mode ultrasound imaging, causing a rapid photothermal ablation effect limited to the region of tumors. Tumor growth was significantly inhibited by the photothermal-chemotherapy due to the triggered release of PTX. Our study provided a promising strategy of NIR laser-mediated photothermal-chemotherapy based on HP-TCS against the tumors (specially, deep orthotopic tumors) with high EphB4 expression.

Gold Nanorod Mediated Chlorhexidine Microparticle Formation and Near-Infrared Light Induced Release

Gold nanorods (GNR) are good light harvesting species for elaboration of near-infrared (NIR) responsive drug delivery systems. Herein, chlorhexidine microparticles are grown directly on the surface of gold nanorods and then stabilized with polyelectrolyte multilayer encapsulation, producing novel composite drug-GNR particles with high drug loading and NIR light sensitivity. Crystallization of chlorhexidine is caused by the ionic strength of the chloride solution that has been demonstrated via formation of a homogeneous porous spherical structure at 0.33 M CaCl₂. By introducing GNRs into the CaCl₂ solution, the nucleation of chlorhexidine molecules and size of produced spheres are affected, since GNRs act as sites for chlorhexidine nucleation. Similarly, when GNRs are replaced by chlorhexidine seeds (5.2 ± 1.7 μm), a core-shell crystal structure is observed. The encapsulated GNR/chlorhexidine composites are responsive to NIR light (840 nm) that increases the temperature at the chlorhexidine crystals, followed by microparticle dissolution and rupture of capsules which is illustrated with confocal microscopy and SEM. Furthermore, a stepwise burst release of chlorhexidine can be induced by multiple cycles of NIR light exposure. The GNR/chlorhexidine composites show good biocompatibility and antimicrobial activity. The proposed method of antibacterial drug release may therefore indicate that this NIR responsive chlorhexidine composite may be useful for future clinical applications.

Specifically Increased Paclitaxel Release in Tumor and Synergetic Therapy by a Hyaluronic Acid-Tocopherol Nanomicelle

Recently, interest in tumor-targeted and site-specific drug release from nanoparticles as a means of drug delivery has increased. In this study, we report a smart nanosized micelle formed by hyaluronic acid (HA) conjugated with d-α-tocopherol succinate (TOS) using a disulfide bond as the linker (HA-SS-TOS, HSST). HSST micelles can specifically bind to the CD44 receptors that are overexpressed by cancer cells. The high levels of glutathione (GSH) in tumor cells selectively break the disulfide bond linker. This effect results in the synchronous release of the payload and a TOS fragment. These two components subsequently demonstrate synergetic anticancer activity. First, we demonstrate that drug release from HSST occurs rapidly in physiological high redox conditions and inside cancer cells. Significant GSH-triggered drug release was also observed in vivo. Furthermore, an in vivo biodistribution study indicated that the HSST micelles efficiently accumulated at the tumor sites, primarily due to an enhanced permeability and retention effect and the efficient binding to the cancer cells that overexpressed the CD44 receptor. Interestingly, the synchronous release of paclitaxel (PTX) and the TOS fragment from the PTX-loaded HSST caused synergetic tumor cell killing and tumor growth inhibition. Our work presents a useful candidate for a drug delivery system that can specifically accumulate at tumor tissue, selectively release its payload and a TOS fragment, and thus display a synergetic anticancer effect.

Specific Photothermal Ablation Therapy of Endometriosis by Targeting Delivery of Gold Nanospheres

Endometriosis is difficult to treat since the side effects of the current therapeutic method and the high recurrence rate; thus, newer and safer therapeutic approaches are urgently needed. This work investigates the enhanced permeability and retention effect of CdTe quantum dots (QDs) and hollow gold nanospheres (HAuNS) in endometriosis to increase the delivery of HAuNS into lesion cells. The surface of HAuNS is successfully conjugated with a TNYL peptide that has specific affinity for the EphB4 receptor, which is a member of the Eph family of receptor tyrosine kinases. It is found that the EphB4 receptor is overexpressed in endometriosis lesions. The data indicate that both QDs and HAuNS can efficiently accumulate in endometriotic lesions through permeable vessels and the TNYL-conjugated HAuNS (TNYL-HAuNS) accumulate more via the interaction with EphB4. The specific photothermal ablation therapy based on TNYL-HAuNS significantly inhibits the growth of the endometriotic volume and induces the atrophy and degeneration of ectopic endometrium with no detectable toxicity to the normal organs. The level of TNF-α and estradiol also significantly decreases in the endometriotic lesions, indicating that the treatment enables a recovery from hormonal imbalance and inflammatory injury. This work can be a valuable reference for future endometriosis therapy.

A pH-responsive glycolipid-like nanocarrier for optimising the time-dependent distribution of free chemical drugs in focal cells

Though Drug delivery systems have achieved accumulation at tumor sites via passive targeting and active targeting, the therapeutic effects are far from perfect. The unsatisfactory results are mainly due to limited drug release from the nanocarriers at tumor sites, while the pharmacological activities of the drug are attributed to the concentration of the free drug and the time maintained at the pharmacological targets. A pH-responsive chitosan based glycolipid-like nanocarrier (CSO-FBA-SA) was fabricated by conjugating stearyl alcohol (SA) to chitosan oligosaccharide (CSO) with the linkage of 4-formylbenzoic acid (FBA). FBA was a kind of aromatic aldehyde carbonyl compounds, which can form the benzoic-imine bond. In the presence of a Schiff's base structure, the carrier showed improved properties and could be quickly degraded in an acidic environment. In order to explore the process and mechanism of the nanocarriers in focal cells, the method for determining the intracellular concentration of released free doxorubicin was established, and the time-dependent change of the DOX-loaded micelles was revealed. The sight of drug release was also obtained with CLSM. The cytotoxicity of the CSO-FBA-SA/DOX against human breast cancer MCF-7 cells increased by 2.75-fold and 3.77-fold in comparison with the CSO-SA/DOX and DOX, respectively. Furthermore, the CSO-FBA-SA/DOX showed a 2.12-fold higher cytotoxicity against the MCF-7 cells than that treated against human ovarian cancer SKOV-3 cells with lower intracellular pH value, which indicated that the cellular inhibition positively correlated with the intracellular pH value. High tumor accumulation and fast drug release of the CSO-FBA-SA/DOX in tumor was responsible for the remarkable tumor growth inhibitory effect. Moreover, the CSO-FBA-SA/DOX could selectively respond to the acidic environment and release DOX in tumor only, which had relatively minimal cytotoxicity towards normal tissues. The results showed that this newly developed glycolipid-like nanocarrier could act as a potential vector for delivering the drug effectively with a low systemic toxicity.

Gold Nanospheres-Stabilized Indocyanine Green as a Synchronous Photodynamic-Photothermal Therapy Platform That Inhibits Tumor Growth and Metastasis

Both photothermal therapy (PTT) and photodynamic therapy (PDT) are phototherapeutic approaches, which have been widely investigated for cancer therapy mediated by an external light source. Here, a nanosystem presenting the synchronous PTT and PDT effect realized through one-step near-infrared (NIR) light irradiation is reported. This system was fabricated by conjugating indocyanine green (ICG) on hollow gold nanospheres (HAuNS) using branched-polyethylenimine (PEI, MW = 10 kDa) as optimal linker, which provided a high ICG payload as well as a covering layer with suitable thickness on HAuNS to maintain ICG fluorescence and reactive oxygen species (ROS) productivity. The resulting system (ICG-PEI-HAuNS) had the molar ratio of ICG:PEI:Au = 3:0.33:5. Compared with free ICG, ICG-PEI-HAuNS exhibited dramatically enhanced stability of ICG molecules and greater intratumoral accumulation. The conjugation of ICG caused significantly higher plasmon absorption of ICG-PEI-HAuNS in the NIR region compared with HAuNS alone, inducing remarkably enhanced photothermal conversion efficiency and synchronous photodynamic effect under NIR light irradiation. Interestingly, compared with PTT or PDT alone, synchronous PTT and PDT produced by ICG-PEI-HAuNS upon NIR light irradiation induced significantly stronger antitumor and metastasis inhibition effects both in vitro and in vivo, which might be a promising strategy for cancer treatment.

A Biodegradable Polyethylenimine-Based Vector Modified by Trifunctional Peptide R18 for Enhancing Gene Transfection Efficiency In Vivo

Lack of capacity to cross the nucleus membrane seems to be one of the main reasons for the lower transfection efficiency of gene vectors observed in vivo study than in vitro. To solve this problem, a new non-viral gene vector was designed. First, a degradable polyethylenimine (PEI) derivate was synthesized by crosslinking low-molecular-weight (LMW) PEI with N-octyl-N-quaternary chitosan (OTMCS), and then adopting a designed trifunctional peptide (RGDC-TAT-NLS) with good tumor targeting, cell uptake and nucleus transport capabilities to modify OTMCS-PEI. The new gene vector was termed as OTMCS-PEI-R18 and characterized in terms of its chemical structure and biophysical parameters. Gene transfection efficiency and nucleus transport mechanism of this vector were also evaluated. The polymer showed controlled degradation and remarkable buffer capabilities with the particle size around 100–300 nm and the zeta potential ranged from 5 mV to 40 mV. Agraose gel electrophoresis showed that OTMCS-PEI-R18 could effectively condensed plasmid DNA at a ratio of 1.0. Besides, the polymer was stable in the presence of sodium heparin and could resist digestion by DNase I at a concentration of 63U DNase I/DNA. OTMCS-PEI-R18 also showed much lower cytotoxicity and better transfection rates compared to polymers OTMCS-PEI-R13, OTMCS-PEI and PEI 25 KDa in vitro and in vivo. Furthermore, OTMCS-PEI-R18/DNA complexes could accumulate in the nucleus well soon and not rely on mitosis absolutely due to the newly incorporated ligand peptide NLS with the specific nuclear delivery pathway indicating that the gene delivery system OTMCS-PEI-R18 could reinforce gene transfection efficiency in vivo.

Multifunctional SPIO/DOX-loaded A54 Homing Peptide Functionalized Dextran-g-PLGA Micelles for Tumor Therapy and MR Imaging

Specific delivery of chemotherapy drugs and magnetic resonance imaging (MRI) contrast agent into tumor cells is one of the issues to highly efficient tumor targeting therapy and magnetic resonance imaging. Here, A54 peptide-functionalized poly(lactic-co-glycolic acid)-grafted dextran (A54-Dex-PLGA) was synthesized. The synthesized A54-Dex-PLGA could self-assemble to form micelles with a low critical micelle concentration of 22.51 μg. mL⁻¹ and diameter of about 50 nm. The synthetic A54-Dex-PLGA micelles can encapsulate doxorubicin (DOX) as a model anti-tumor drug and superparamagnetic iron oxide (SPIO) as a contrast agent for MRI. The drug-encapsulation efficiency was about 80% and the in vitro DOX release was prolonged to 72 hours. The DOX/SPIO-loaded micelles could specifically target BEL-7402 cell line. In vitro MRI results also proved the specific binding ability of A54-Dex-PLGA/DOX/SPIO micelles to hepatoma cell BEL-7402. The in vivo MR imaging experiments using a BEL-7402 orthotopic implantation model further validated the targeting effect of DOX/SPIO-loaded micelles. In vitro and in vivo anti-tumor activities results showed that A54-Dex-PLGA/DOX/SPIO micelles revealed better therapeutic effects compared with Dex-PLGA/DOX/SPIO micelles and reduced toxicity compared with commercial adriamycin injection.

Appropriate Size of Magnetic Nanoparticles for Various Bioapplications in Cancer Diagnostics and Therapy

The development of multifunctional nanoparticles has attracted increasing attention. The versatility of nanoparticles largely depends on their physiochemical properties (especially size). However, the optimized size range may be different for the bioapplications of each function associated with multifunctional nanoparticles. It is important to investigate every optimized size range to ascertain which size enables the best function of the nanoparticles before deciding their final size. In this work, we synthesized a series of monodisperse Fe3O4 nanoparticles with identical surface properties ranging in size from 60 to 310 nm and systematically investigated their biobehavior and application. Our data indicate that compared to their large counterparts, small Fe3O4 nanoparticles exhibited greater cellular internalization and deeper penetration into multicellular spheroids, thus enabling a higher photothermal ablation efficacy in vitro. Interestingly, larger Fe3O4 nanoparticles showed greater accumulation in tumors, thereby inducing more efficient tumor growth inhibition. In addition, 120 nm may be the optimal diameter of Fe3O4 nanoparticles for magnetic resonance imaging and photoacoustic tomography in vitro. However, more efficient in vivo imaging mediated by Fe3O4 nanoparticles will predominantly depend on their high accumulation. Our work presents a different appropriate size range for each biofunction of Fe3O4 nanoparticles, which could be a valuable reference for future nanoparticle design.

Specific photothermal therapy to the tumors with high EphB4 receptor expression

Photothermal therapy (PTT) employs photo-absorbing agents to generate heat from optical energy, leading to the 'burning' of tumor cells. Real-time imaging of in vivo distribution of photothermal agents and monitoring of post-treatment therapeutic outcomes are very important to design and optimize personalized PTT treatment. In this work, we used chitosan-stearic acid copolymer (CSO-SA) to encapsulate hollow gold nanospheres (HAuNS) and near-infrared (NIR) fluorescent tracer, DiR. Then, the surface of nanoparticles was further conjugated with a peptide (TNYL), which facilitates EphB4-positive tumor targeting delivery. Using a paired tumor mode in vivo and a double tumor-cell co-culture strategy in vitro, we demonstrated the feasibility of increasing the accumulation of our nanoparticles (DiR loaded and TNYL-CSO-SA coated HAuNS (DTCSH)) into EphB4-positive tumors through interaction between TNYL-peptide on the nanoparticles and EpHB4 receptors on tumor cells. When combined with NIR laser irradiation, our nanoparticles induced more EphB4-positive tumor cells death in vitro. We further developed optical imaging to temporally and spatially monitor the biodistribution of DTCSH. Under NIR laser irradiation, PTT exhibited dramatically stronger antitumor effect against EphB4-positive tumors than EphB4-negative tumors. This was attributed to enhanced accumulation of our nanoparticles in EphB4-positive tumors.

Redox-responsive polymer-drug conjugates based on doxorubicin and chitosan oligosaccharide-g-stearic acid for cancer therapy

Here, a biodegradable polymer-drug conjugate of doxorubicin (DOX) conjugated with a stearic acid-grafted chitosan oligosaccharide (CSO-SA) was synthesized via disulfide linkers. The obtained polymer-drug conjugate DOX-SS-CSO-SA could self-assemble into nanosized micelles in aqueous medium with a low critical micelle concentration. The size of the micelles was 62.8 nm with a narrow size distribution. In reducing environments, the DOX-SS-CSO-SA could rapidly disassemble result from the cleavage of the disulfide linkers and release the DOX. DOX-SS-CSO-SA had high efficiency for cellular uptake and rapidly released DOX in reductive intracellular environments. In vitro antitumor activity tests showed that the DOX-SS-CSO-SA had higher cytotoxicity against DOX-resistant cells than free DOX, with reversal ability up to 34.8-fold. DOX-SS-CSO-SA altered the drug distribution in vivo, which showed selectively accumulation in tumor and reduced nonspecific accumulation in hearts. In vivo antitumor studies demonstrated that DOX-SS-CSO-SA showed efficient suppression on tumor growth and relieved the DOX-induced cardiac injury. Therefore, DOX-SS-CSO-SA is a potential drug delivery system for safe and effective cancer therapy.

Specific targeting of A54 homing peptide-functionalized dextran-g-poly(lactic-co-glycolic acid) micelles to tumor cells

The delivery of chemotherapeutics into tumor cells is a fundamental knot for tumor-target therapy to improve the curative effect and avoid side effects. Here, A54 peptide-functionalized poly(lactic-co-glycolic acid)-grafted dextran (A54-Dex-PLGA) was synthesized. The synthesized A54-Dex-PLGA self-assembled to form micelles with a low critical micelle concentration of 16.79 μg·mL⁻¹ and diameter of about 50 nm. With doxorubicin (DOX) base as a model antitumor drug, the drug-encapsulation efficiency of DOX-loaded A54-Dex-PLGA micelles (A54-Dex-PLGA/DOX) reached up to 75%. In vitro DOX release from the A54-Dex-PLGA/DOX was prolonged to 72 hours. The A54-Dex-PLGA micelles presented excellent internalization ability into hepatoma cells (BEL-7402 cell line and HepG2 cell line) in vitro, and the cellular uptake of the micelles by the BEL-7402 cell line was specific, which was demonstrated by the blocking experiment. In vitro antitumor activity studies confirmed that A54-Dex-PLGA/DOX micelles suppressed tumor-cell (BEL-7402 cell) growth more effectively than Dex-PLGA micelles. Furthermore, in vivo biodistribution testing demonstrated that the A54-Dex-PLGA micelles had a higher distribution ability to BEL-7402 tumors than that to HepG2 tumors.

Targeting the Eph System with Peptides and Peptide Conjugates

Eph receptor tyrosine kinases and ephrin ligands constitute an important cell communication system that controls development, tissue homeostasis and many pathological processes. Various Eph receptors/ephrins are present in essentially all cell types and their expression is often dysregulated by injury and disease. Thus, the 14 Eph receptors are attracting increasing attention as a major class of potential drug targets. In particular, agents that bind to the extracellular ephrin-binding pocket of these receptors show promise for medical applications. This pocket comprises a broad and shallow groove surrounded by several flexible loops, which makes peptides particularly suitable to target it with high affinity and selectivity. Accordingly, a number of peptides that bind to Eph receptors with micromolar affinity have been identified using phage display and other approaches. These peptides are generally antagonists that inhibit ephrin binding and Eph receptor/ ephrin signaling, but some are agonists mimicking ephrin-induced Eph receptor activation. Importantly, some of the peptides are exquisitely selective for single Eph receptors. Most identified peptides are linear, but recently the considerable advantages of cyclic scaffolds have been recognized, particularly in light of potential optimization towards drug leads. To date, peptide improvements have yielded derivatives with low nanomolar Eph receptor binding affinity, high resistance to plasma proteases and/or long in vivo half-life, exemplifying the merits of peptides for Eph receptor targeting. Besides their modulation of Eph receptor/ephrin function, peptides can also serve to deliver conjugated imaging and therapeutic agents or various types of nanoparticles to tumors and other diseased tissues presenting target Eph receptors.

Eph receptors and ephrins: therapeutic opportunities

The erythropoietin-producing hepatocellular carcinoma (Eph) receptor tyrosine kinase family plays important roles in developmental processes, adult tissue homeostasis, and various diseases. Interaction with Eph receptor-interacting protein (ephrin) ligands on the surface of neighboring cells triggers Eph receptor kinase-dependent signaling. The ephrins can also transmit signals, leading to bidirectional cell contact-dependent communication. Moreover, Eph receptors and ephrins can function independently of each other through interplay with other signaling systems. Given their involvement in many pathological conditions ranging from neurological disorders to cancer and viral infections, Eph receptors and ephrins are increasingly recognized as attractive therapeutic targets, and various strategies are being explored to modulate their expression and function. Eph receptor/ephrin upregulation in cancer cells, the angiogenic vasculature, and injured or diseased tissues also offer opportunities for Eph/ephrin-based targeted drug delivery and imaging. Thus, despite the challenges presented by the complex biology of the Eph receptor/ephrin system, exciting possibilities exist for therapies exploiting these molecules.

TNYL peptide functional chitosan-g-stearate conjugate micelles for tumor specific targeting

Nowadays, a real challenge in cancer therapy is to design drug delivery systems that can achieve high concentrations of drugs at the target site for improved therapeutic effect with reduced side effects. In this research, we designed and synthesized a homing peptide-(TNYLFSPNGPIA, TNYL) modified chitosan-g-stearate (CS) polymer micelle (named T-CS) for targeting delivery. The peptide displayed specific binding affinity to EphB4 which is a member of the Eph family of receptor tyrosine protein kinases. The amphiphilic polymer T-CS can gather into micelles by themselves in an aqueous environment with a low critical micelle concentration value (91.2 μg/L) and nano-scaled size (82.1±2.8 nm). The drug encapsulation efficiency reached 86.43% after loading the hydrophobic drug doxorubicin (DOX). The cytotoxicity of T-CS/DOX against SKOV3 cells was enhanced by approximately 2.3-fold when compared with CS/DOX. The quantitative and qualitative analysis for cellular uptake indicated that TNYL modification can markedly increase cellular internalization in the EphB4-overexpressing SKOV3 cell line, especially with a short incubation time. It is interesting that relatively higher uptake of the T-CS/DOX micelles by SKOV3 cells (positive-EphB4) than A549 cells (negative-EphB4) was observed when the two cells were co-incubated. Furthermore, in vivo distribution experiment using a bilateral-tumor model showed that there was more fluorescence accumulation in the SKOV3 tumor than in the A549 tumor over the whole experiment. These results suggest that TNYL-modified CS micelles may be promising drug carriers as targeting therapy for the EphB4-overexpressing tumor.

Amphiphilic designer nano-carriers for controlled release: from drug delivery to diagnostics

Our review highlights lipid liquid crystal nanocarriers, essentially their design considerations and sugar-based materials for specific targeted delivery.

Thermo-responsive gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) core–corona nanoparticles as a drug delivery system

Preparation of thermo-responsive poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) copolymer-stabilized gold nanoparticles for drug delivery.