Doxorubicin-tethered responsive gold nanoparticles facilitate intracellular drug delivery for overcoming multidrug resistance in cancer cells

Combination of apolipoprotein A1-modi liposome-doxorubicin with autophagy inhibitors overcame drug resistance in vitro

Multidrug resistance (MDR) represents the major drawback in chemotherapy. Liposome-based approaches could reverse MDR to some extent through circumventing the active efflux effect of P-glycoprotein. However, the reverse power of liposome is very limited because the nontargeting liposome is inefficient to deliver drugs to tumor actively. Besides, autophagy could reinforce the resistance of tumor cells to the cytotoxicity of intracellular drugs. Here, liposomal doxorubicin (Lipodox) that was conjugated with apolipoprotein A1-apo-Lipodox, was employed in tumor targeting delivery of doxorubicin. In the experiments, apo-Lipodox could enter cells effectively and reverse MDR more efficiently than their nontargeting counterpart. Autophagy occurred in this process and contributed to the survival of tumor cells. Combination use of autophagy inhibitors could enhance the cytotoxicity of apo-Lipodox and reverse drug resistance to a higher degree. We propose that this strategy holds promise to overcome MDR in human cancer.

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.

Cytochrome c end-capped mesoporous silica nanoparticles as redox-responsive drug delivery vehicles for liver tumor-targeted triplex therapy in vitro and in vivo

To develop carriers for efficient anti-cancer drug delivery with reduced side effects, a biocompatible and redox-responsive nanocontainer based on mesoporous silica nanoparticles (MSNs) for tumor-targeted triplex therapy was reported in this study. The nanocontainer was fabricated by immobilizing cytochrome c (CytC) onto the MSNs as sealing agent via intermediate linkers of disulfide bonds for redox-responsive intracellular drug delivery. AS1411 aptamer was further tailored onto MSNs for cell/tumor targeting. The successful construction of redox- responsive MSNs was confirmed by BET/BJH analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermogravimetric analysis (TGA), respectively. Detailed investigations demonstrated that anticancer drug of doxorubicin (DOX) loaded nanocontainer could be triggered by reductant (e.g. glutathione) within cellular microenvironment and release DOX to induce tumor cell apoptosis in vitro. More importantly, the nanocontainer displayed great potential for tumor targeting and achieved triplex therapy effects on the tumor inhibition in vivo through the loading DOX, gatekeeper of CytC and AS1411 aptamer, which were reflected by the change of tumor size, TUNEL staining and HE staining assays.

Green synthesis of bacterial gold nanoparticles conjugated to resveratrol as delivery vehicles

Bio-directed synthesis of metal nanoparticles is gaining importance in view of their biocompatibility, low toxicity and eco-friendly characteristics. The present study describes the application of resveratrol conjugated gold nanoparticles as effective delivery vehicles. The green chemistry approach was used for the synthesis of gold nanoparticles by using the culture supernatant of Delftia sp. strain KCM-006. The synthesized gold nanoparticles were mono-dispersed, spherical in shape with an average size of 11.3 nm. They were found to be photoluminescent and crystalline in nature with a zeta potential of -25 mV, indicating their high stability. Resveratrol, an anticancer drug, was conjugated to these gold nanoparticles (RSV-AuNP). The cell viability and immunocytochemistry analysis with human lung cancer cell line (A549) demonstrated that RSV-AuNPs were 65% more effective as drug when compared to resveratrol alone. In vitro observations on the drug release from these nanoparticles exhibited pH dependency; the release was significant (95%) under acidic conditions (pH 5.2) when compared to physiological conditions (pH 7.4).

Polyphosphoester-based nanoparticles with viscous flow core enhanced therapeutic efficacy by improved intracellular drug release

The intracellular drug release rate from the hydrophobic core of self-assembled nanoparticles can significantly affect the therapeutic efficacy. Currently, the hydrophobic core of many polymeric nanoparticles which are usually composed of poly(ε-caprolactone) (PCL), polylactide (PLA), or poly(D, L-lactide-co-glycolide) (PLGA) may hinder the diffusion of drug from the core because of their glassy state at room temperature. To investigate the effect of the hydrophobic core state on therapeutic efficacy, we synthesized an amphiphilic diblock copolymers of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polyphosphoester, which were in a viscous flow state at room temperature. The obtained copolymers self-assembled into core-shell nanoparticles, which efficiently encapsulate doxorubicin (DOX) in the hydrophobic polyphosphoester core (NP(PPE)/DOX). As speculated, compared with the nanoparticles bearing glassy core (hydrophobic PLA core, NP(PLA)/DOX), the encapsulated DOX was more rapidly released from NP(PPE)/DOX with viscous flow core, resulting in significantly increased cytotoxicity. Accordingly, the improved intracellular drug release from viscous flow core enhances the inhibition of tumor growth, suggesting the nanoparticles bearing viscous flow core show great potential in cancer therapy.

Cationic oligo(p-phenylene vinylene) materials for combating drug resistance of cancer cells by light manipulation

An unconventional strategy that can be temporally and remotely activated with light to combat the drug resistance of cancer cells is developed. A cell-membrane-anchored photosensitizer (OPV) is used to enhance anticancer drug uptake and restore toxicity in resistant cancer cells. This method recovers the activity of the already established anticancer drugs, and provides a new strategy for the development of light manipulation to combat anticancer resistance.

Intracellular redox-activated anticancer drug delivery by functionalized hollow mesoporous silica nanoreservoirs with tumor specificity

In this study, a type of intracellular redox-triggered hollow mesoporous silica nanoreservoirs (HMSNs) with tumor specificity was developed in order to deliver anticancer drug (i.e., doxorubicin (DOX)) to the target tumor cells with high therapeutic efficiency and reduced side effects. Firstly, adamantanamine was grafted onto the orifices of HMSNs using a redox-cleavable disulfide bond as an intermediate linker. Subsequently, a synthetic functional molecule, lactobionic acid-grafted-β-cyclodextrin (β-CD-LA), was immobilized on the surface of HMSNs through specific complexation with the adamantyl group, where β-CD served as an end-capper to keep the loaded drug within HMSNs. β-CD-LA on HMSNs could also act as a targeting agent towards tumor cells (i.e., HepG2 cells), since the lactose group in β-CD-LA is a specific ligand binding with the asialoglycoprotein receptor (ASGP-R) on HepG2 cells. In vitro studies demonstrated that DOX-loaded nanoreservoirs could be selectively endocytosed by HepG2 cells, releasing therapeutic DOX into cytoplasm and efficiently inducing the apoptosis and cell death. In vivo investigations further confirmed that DOX-loaded nanoreservoirs could permeate into the tumor sites and actively interact with tumor cells, which inhibited the tumor growth with the minimized side effect. On the whole, this drug delivery system exhibits a great potential as an efficient carrier for targeted tumor therapy in vitro and in vivo.

Silica nanovehicles endow arsenic trioxide with an ability to effectively treat cancer cells and solid tumors

Arsenic trioxide is a clinical drug that can be used to successfully treat acute promyelocytic leukemia. However, its therapeutic effect on solid tumors is limited because of the poor pharmacokinetics and dose-limiting toxicity. Here, we report a facile strategy to achieve high anticancer activity of arsenic trioxide by loading the nanoparticulate prodrug into hollow silica inorganic nanoparticles. Because of the appropriate size, pH sensitivity, and surface targeted modification, this smart nanosized drug system can deliver arsenic trioxide into cancer cells efficiently and exhibits much higher cytotoxicity to a variety of cancer cells than free arsenic trioxide. Moreover, this nanomedicine can further promote the differentiation and inhibit the migration of cancer cells. In vivo results suggest that this drug delivery system can significantly inhibit the growth of solid tumors without adverse side effects. This study highlights a feasible drug delivery strategy to expand the use of arsenic trioxide for the effective treatment of solid tumors.

Targeted delivery of doxorubicin into tumor cells via MMP-sensitive PEG hydrogel-coated magnetic iron oxide nanoparticles (MIONPs)

Targeting tumors with nano-scale delivery systems shows promise to improve the therapeutic effects of chemotherapeutic drugs. However, the limited specificity of current nano-scale systems for cancer tissues prevents realization of their full clinical potential. Here, we demonstrate an effective approach to creating as targeted nanocarriers for drug delivery: MIONPs coated with integrin-targeted and matrix-metalloproteinase (MMP)-sensitive PEG hydrogel scaffolds. The functional PEG hydrogel coating has been designed for active loading as well as triggered intra-cellular release of the cancer therapeutic agent doxorubicin (DOX). Our study demonstrated that coated nanocarriers could be taken into cancer cells 11 times more efficiently than uncoated ones. Furthermore, confocal laser scanning microscopy images revealed that these targeted nanocarriers could efficiently deliver and release DOX into the nuclei of HeLa cells within 2h. Coating MIONPs with multifunctional PEG hydrogel could be a promising alternative to existing vehicles for targeted delivery of DOX into tumor tissue.

Nanotechnology-based drug delivery systems for treatment of oral cancer: a review

Oral cancer (oral cavity and oropharynx) is a common and aggressive cancer that invades local tissue, can cause metastasis, and has a high mortality rate. Conventional treatment strategies, such as surgery and chemoradiotherapy, have improved over the past few decades; however, they remain far from optimal. Currently, cancer research is focused on improving cancer diagnosis and treatment methods (oral cavity and oropharynx) nanotechnology, which involves the design, characterization, production, and application of nanoscale drug delivery systems. In medicine, nanotechnologies, such as polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, gold nanoparticles, hydrogels, cyclodextrin complexes, and liquid crystals, are promising tools for diagnostic probes and therapeutic devices. The objective of this study is to present a systematic review of nanotechnology-based drug delivery systems for oral cancers.

Smart pH-responsive nanocarriers based on nano-graphene oxide for combined chemo- and photothermal therapy overcoming drug resistance

A pH-responsive nanocarrier is developed by coating nanoscale graphene oxide (NGO) with dual types of polymers, polyethylene glycol (PEG) and poly(allylamine hydrochloride) (PAH), the latter of which is then modified with 2,3-dimethylmaleic anhydride (DA) to acquire pH-dependent charge reversibility. After loading with doxorubicin (DOX), a chemotherapy drug, the obtained NGO-PEG-DA/DOX complex exhibits a dual pH-responsiveness, showing markedly enhanced cellular uptake under the tumor microenvironmental pH, and accelerated DOX release under a further lowered pH inside cell lysosomes. Combining such a unique behavior with subsequently slow efflux of DOX, NGO-PEG-DA/DOX offers remarkably improved cell killing for drug-resistant cancer cells under the tumor microenvironmental pH in comparison with free DOX. Exploiting its excellent photothermal conversion ability, combined chemo- and photothermal therapy is further demonstrated using NGO-PEG-DA/DOX, realizing a synergistic therapeutic effect. This work presents a novel design of surface chemistry on NGO for the development of smart drug delivery systems responding to the tumor microenvironment and external physical stimulus, with the potential to overcome drug resistance.

Redox-responsive nanocarrier based on heparin end-capped mesoporous silica nanoparticles for targeted tumor therapy in vitro and in vivo

This study reports a smart controlled drug release system based on mesoporous silica nanoparticles (MSNs) for targeted drug delivery. The system was fabricated by employing heparin as an end-capping agent to seal the mesopores of MSNs via disulfide bonds as intermediate linkers for intracellular glutathione triggered drug release. Lactobionic acid molecules were then coupled to heparin end-capped MSNs that serve as targeting motifs for facilitating the uptake of doxorubicin (DOX) loaded MSNs by HepG2 cells and tumors, respectively. Detailed investigations demonstrated that the fabricated drug delivery systems could deliver DOX to cancer cells to induce cell apoptosis in vitro and tumor tissue for the inhibition of tumor growth in vivo with minimal side effects. The study affords a promising nanocarrier for redox-responsive cargo delivery with high curative efficiency for cancer therapy.

Calcium-channel blocking and nanoparticles-based drug delivery for treatment of drug-resistant human cancers

Background: Cancer cell chemoresistance is one of the major limitations to successful cancer treatment and one of the factors that is responsible for the possible recurrence of the disease. Here, we aimed to combine a calcium-channel blocker, verapamil, with an alternative delivery of the anti-cancer drug, doxorubicin, using nanostructural materials. This approach could reduce the cellular resistance to chemotherapeutics agents. Results: The outcome of this complex approach on cellular viability was investigated by using various assays in both a time- and concentration-dependent manner: WST-1, flow cytometry cell viability assay, fluorescence microscopy, DNA fragmentation, and TUNEL labeling of apoptotic cells. Conclusion: All of these analytical assays confirmed the ability to reduce the chemoresistance of the cancer cells based on the proposed procedure.

The optical, photothermal, and facile surface chemical properties of gold and silver nanoparticles in biodiagnostics, therapy, and drug delivery

Nanotechnology is a rapidly growing area of research in part due to its integration into many biomedical applications. Within nanotechnology, gold and silver nanostructures are some of the most heavily utilized nanomaterial due to their unique optical, photothermal, and facile surface chemical properties. In this review, common colloid synthesis methods and biofunctionalization strategies of gold and silver nanostructures are highlighted. Their unique properties are also discussed in terms of their use in biodiagnostic, imaging, therapeutic, and drug delivery applications. Furthermore, relevant clinical applications utilizing gold and silver nanostructures are also presented. We also provide a table with reviews covering related topics.

Perylene-derived single-component organic nanoparticles with tunable emission: efficient anticancer drug carriers with real-time monitoring of drug release

An organic nanoparticle-based drug delivery system with high drug loading efficacy (∼79 wt %) was developed using a perylene-derived photoremovable protecting group, namely, perylene-3,4,9,10-tetrayltetramethanol (Pe(OH)4). The anticancer drug chlorambucil was protected by coupling with Pe(OH)4 to form photocaged nanoparticles (Pe(Cbl)4). The photorelease mechanism of chlorambucil from the Pe(Cbl)4 conjugate was investigated experimentally by high-resolution mass spectrometry and theoretically by density functional theory calculations. The Pe(Cbl)4 nanoparticles perform four important roles: (i) a nanocarrier for drug delivery, (ii) a phototrigger for drug release, (iii) a fluorescent chromophore for cell imaging, and (iv) a photoswitchable fluorophore for real-time monitoring of drug release. Tunable emission of the perylene-derived nanoparticles was demonstrated by comparing the emission properties of the Pe(OH)4 and Pe(Cbl)4 nanoparticles with perylene-3-ylmethanol. These nanoparticles were subsequently employed in cell imaging for investigating their intracellular localization. Furthermore, the in vivo toxicity of the Pe(OH)4 nanoparticles was investigated using the mouse model. Histological tissue analysis of five major organs, i.e., heart, kidney, spleen, liver, and lung, indicates that the nanoparticles did not show any obvious damage to these major organs under the experimental conditions. The current research presents a successful example of integrating multiple functions into single-component organic nanoparticles for drug delivery.

Neuropilin-1-targeted gold nanoparticles enhance therapeutic efficacy of platinum(IV) drug for prostate cancer treatment

Platinum-based anticancer drugs such as cisplatin, oxaliplatin, and carboplatin are some of the most potent chemotherapeutic agents but have limited applications due to severe dose-limiting side effects and a tendency for cancer cells to rapidly develop resistance. The therapeutic index can be improved through use of nanocarrier systems to target cancer cells efficiently. We developed a unique strategy to deliver a platinum(IV) drug to prostate cancer cells by constructing glutathione-stabilized (Au@GSH) gold nanoparticles. Glutathione (GSH) has well-known antioxidant properties, which lead to cancer regression. Here, we exploit the advantages of both the antioxidant properties and high surface-area-to-volume ratio of Au@GSH NPs to demonstrate their potential for delivery of a platinum(IV) drug by targeting the neuropilin-1 receptor (Nrp-1). A lethal dose of a platinum(IV) drug functionalized with the Nrp-1-targeting peptide (CRGDK) was delivered specifically to prostate cancer cells in vitro. Targeted peptide ensures specific binding to the Nrp-1 receptor, leading to enhanced cellular uptake level and cell toxicity. The nanocarriers were themselves nontoxic, but exhibited high cytotoxicity and increased efficacy when functionalized with the targeting peptide and drug. The uptake of drug-loaded nanocarriers is dependent on the interaction with Nrp-1 in cell lines expressing high (PC-3) and low (DU-145) levels of Nrp-1, as confirmed through inductively coupled plasma mass spectrometry and confocal microscopy. The nanocarriers have effective anticancer activity, through upregulation of nuclear factor kappa-B (NF-κB) protein (p50 and p65) expression and activation of NF-κB-DNA-binding activity. Our preliminary investigations with platinum(IV)-functionalized gold nanoparticles along with a targeting peptide hold significant promise for future cancer treatment.

Multifunctional HER2-antibody conjugated polymeric nanocarrier-based drug delivery system for multi-drug-resistant breast cancer therapy

Nanotechnology-based medical approaches have made tremendous potential for enhancing the treatment efficacy with minimal doses of chemotherapeutic drugs against cancer. In this study, using tamoxifen (Tam), biodegradable antibody conjugated polymeric nanoparticles (NPs) was developed to achieve targeted delivery as well as sustained release of the drug against breast cancer cells. Poly(D,L-lactic-co-glycolic acid) (PLGA) NPs were stabilized by coating with poly(vinyl alcohol) (PVA), and copolymer polyvinyl-pyrrolidone (PVP) was used to conjugate herceptin (antibody) with PLGA NPs for promoting the site-specific intracellular delivery of Tam against HER2 receptor overexpressed breast cancer (MCF-7) cells. The Tam-loaded PVP-PLGA NPs and herceptin-conjugated Tam-loaded PVP-PLGA NPs were characterized in terms of morphology, size, surface charge, and structural chemistry by dynamic light scattering (DLS), Transmission electron microscopy (TEM), ζ potential analysis, 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FT-IR) spectroscopy. pH-based drug release property and the anticancer activity (in vitro and in vivo models) of the herceptin conjugated polymeric NPs were evaluated by flow cytometry and confocal image analysis. Besides, the extent of cellular uptake of drug via HER2 receptor-mediated endocytosis by herceptin-conjugated Tam-loaded PVP-PLGA NPs was examined. Furthermore, the possible signaling pathway of apoptotic induction in MCF-7 cells was explored by Western blotting, and it was demonstrated that drug-loaded PLGA NPs were capable of inducing apoptosis in a caspase-dependent manner. Hence, this nanocarrier drug delivery system (DDS) not only actively targets a multidrug-resistance (MDR) associated phenotype (HER2 receptor overexpression) but also improves therapeutic efficiency by enhancing the cancer cell targeted delivery and sustained release of therapeutic agents.

Dual imaging-guided photothermal/photodynamic therapy using micelles

We report a type of photosensitizer (PS)-loaded micelles integrating cyanine dye as potential theranostic micelles for precise anatomical tumor localization via dual photoacoustic (PA)/near-infrared fluorescent (NIRF) imaging modalities, and simultaneously superior cancer therapy via sequential synergistic photothermal therapy (PTT)/photodynamic therapy (PDT). The micelles exhibit enhanced photostability, cell internalization and tumor accumulation. The dual NIRF/PA imaging modalities of the micelles cause the high imaging contrast and spatial resolution of tumors, which provide precise anatomical localization of the tumor and its inner vasculature for guiding PTT/PDT treatments. Moreover, the micelles can generate severe photothermal damage on cancer cells and destabilization of the lysosomes upon PTT photoirradiation, which subsequently facilitate synergistic photodynamic injury via PS under PDT treatment. The sequential treatments of PTT/PDT trigger the enhanced cytoplasmic delivery of PS, which contributes to the synergistic anticancer efficacy of PS. Our strategy provides a dual-modal cancer imaging with high imaging contrast and spatial resolution, and subsequent therapeutic synergy of PTT/PDT for potential multimodal theranostic application.

Au@Pt nanostructures: a novel photothermal conversion agent for cancer therapy

Due to aspect ratio dependent localized surface plasmon resonance (SPR), gold nanorods (Au NRs) can be tuned to have a strong absorption in the near infrared region (NIR) and convert light to heat energy, which shows promises in cancer photothermal therapy. In this study, we introduced another more efficient NIR photothermal agent, Au nanorods coated with a shell of Pt nanodots (Au@Pt nanostructures). After surface modification with Pt dots, the Au@Pt nanostructure became a more efficient photothermal therapy agent as verified both in vitro and in vivo. To clarify the mechanism, we assessed the interaction between the MDA-MB-231 cells with Au@Pt or Au NRs. Results showed that the slightly higher uptake and the reduced sensitivity of the longitudinal SPR band on the intracellular aggregate state may contribute to the better photothermal efficiency for Au@Pt NRs. The theoretical studies further confirmed that the Au@Pt nanostructure itself exhibited better photothermal efficiency compared to Au NRs. These advantages make the Au@Pt nanostructure a more attractive and effective agent for cancer photothermal therapy than general Au NRs.

Doxorubicin-loaded silicon nanowires for the treatment of drug-resistant cancer cells

Multidrug resistance (MDR) remains a major challenge for cancer treatment thus far. Free doxorubicin (DOX, one of the most widely used chemotherapy agents for cancer treatment) generally features a large value of resistant factor (RF), which is regarded as a significant parameter to assess therapeutic efficiency of cross-resistance. To address this issue, we herein present a kind of silicon nanowires (SiNWs)-based drug nanocarriers (SiNW-DOX), which is high-efficacy for treatment of drug-resistant cancer cells. Typically, drug-resistance cancer cells (e.g., MCF-7/ADR cells) can be significantly inhibited by the SiNWs-based nanocarriers, exhibiting ∼10% cell viability during 72-h incubation with the SiNWs-DOX (80 μg mL(-1) DOX), which is in sharp contrast to free DOX-treated cells preserving ∼40% cell viability. Remarkably, the RF value of SiNW-DOX is as low as ∼2.0, which is much better than that (∼300) of free DOX under the same experiment conditions. To the best of our knowledge, it is the lowest RF value ever reported by nanomaterials-based drug carriers (3.3-24.7).

Real-time monitoring of anticancer drug release with highly fluorescent star-conjugated copolymer as a drug carrier

Chemotherapy is one of the major systemic treatments for cancer, in which the drug release kinetics is a key factor for drug delivery. In the present work, a versatile fluorescence-based real-time monitoring system for intracellular drug release has been developed. First, two kinds of star-conjugated copolymers with different connections (e.g., pH-responsive acylhydrazone and stable ether) between a hyperbranched conjugated polymer (HCP) core and many linear poly(ethylene glycol) (PEG) arms were synthesized. Owing to the amphiphilic three-dimensional architecture, the star-conjugated copolymers could self-assemble into multimicelle aggregates from unimolecular micelles with excellent emission performance in the aqueous medium. When doxorubicin (DOX) as a model drug was encapsulated into copolymer micelles, the emission of star-conjugated copolymer and DOX was quenched. In vitro biological studies revealed that fluorescent intensities of both star-conjugated copolymer and DOX were activated when the drug was released from copolymeric micelles, resulting in the enhanced cellular proliferation inhibition against cancer cells. Importantly, pH-responsive feature of the star-conjugated copolymer with acylhydrazone linkage exhibited accelerated DOX release at a mildly acidic environment, because of the fast breakage of acylhydrazone in endosome or lysosome of tumor cells. Such fluorescent star-conjugated copolymers may open up new perspectives to real-time study of drug release kinetics of polymeric drug delivery systems for cancer therapy.

Emerging advances in nanomedicine with engineered gold nanostructures

Gold nanostructures possess unique characteristics that enable their use as contrast agents, as therapeutic entities, and as scaffolds to adhere functional molecules, therapeutic cargo, and targeting ligands. Due to their ease of synthesis, straightforward surface functionalization, and non-toxicity, gold nanostructures have emerged as powerful nanoagents for cancer detection and treatment. This comprehensive review summarizes the progress made in nanomedicine with gold nanostructures (1) as probes for various bioimaging techniques including dark-field, one-photon and two-photon fluorescence, photothermal optical coherence tomography, photoacoustic tomography, positron emission tomography, and surface-enhanced Raman scattering based imaging, (2) as therapeutic components for photothermal therapy, gene and drug delivery, and radiofrequency ablation, and (3) as a theranostic platform to simultaneously achieve both cancer detection and treatment. Distinct from other published reviews, this article also discusses the recent advances of gold nanostructures as contrast agents and therapeutic actuators for inflammatory diseases including atherosclerotic plaque and arthritis. For each of the topics discussed above, the fundamental principles and progress made in the past five years are discussed. The review concludes with a detailed future outlook discussing the challenges in using gold nanostructures, cellular trafficking, and translational considerations that are imperative for rapid clinical viability of plasmonic nanostructures, as well as the significance of emerging technologies such as Fano resonant gold nanostructures in nanomedicine.

Reaction of dermal structures to subcutaneous injection of gold nanoparticles to CBA mice

The reactions of dermal structures to subcutaneous injections of gold nanoparticles were studied in CBA mice. Routes of the nanoparticles migration after injection and the mechanisms of their effects on the adjacent tissues were studied. Injected nanoparticles were phagocytosed by macrophages; some of them migrated to lymphoid follicles of the lymph node, while others migrated into blood vessels, where the particles were released from the macrophage cytoplasm into circulating blood. The endothelium was destroyed as a result of the toxic activity of macrophages loaded with nanoparticles. Two mechanisms of angiogenesis inhibition and death of blood vessels in tissues after injection of nanoparticles were distinguished. One mechanism consisted in deactivation of macrophages producing vascular endothelium growth factor inducing the formation of endothelium in the growing blood vessels, but not in direct inhibition of this factor. The other mechanism was realized through direct death of the endothelium in migration of macrophages through the vascular wall.

Polysaccharide-gold nanocluster supramolecular conjugates as a versatile platform for the targeted delivery of anticancer drugs

Through the high affinity of the β-cyclodextrin (β-CD) cavity for adamantane moieties, novel polysaccharide-gold nanocluster supramolecular conjugates (HACD-AuNPs) were successfully constructed from gold nanoparticles (AuNPs) bearing adamantane moieties and cyclodextrin-grafted hyaluronic acid (HACD). Due to their porous structure, the supramolecular conjugates could serve as a versatile and biocompatible platform for the loading and delivery of various anticancer drugs, such as doxorubicin hydrochloride (DOX), paclitaxel (PTX), camptothecin (CPT), irinotecan hydrochloride (CPT-11), and topotecan hydrochloride (TPT), by taking advantage of the controlled association/dissociation of drug molecules from the cavities formed by the HACD skeletons and AuNPs cores as well as by harnessing the efficient targeting of cancer cells by hyaluronic acid. Significantly, the release of anticancer drugs from the drug@HACD-AuNPs system was pH-responsive, with more efficient release occurring under a mildly acidic environment, such as that in a cancer cell. Taking the anticancer drug DOX as an example, cell viability experiments revealed that the DOX@HACD-AuNPs system exhibited similar tumor cell inhibition abilities but lower toxicity than free DOX due to the hyaluronic acid reporter-mediated endocytosis. Therefore, the HACD-AuNPs supramolecular conjugates may possess great potential for the targeted delivery of anticancer drugs.

A complementary strategy for enhancement of nanoparticle intracellular uptake

PURPOSE

The complementary strategy by combining targeting ligand-mediated selectivity and CPP-mediated transmembrane function could be exploit synergies for enhancing cellular uptake of nanoparticles with negative charge. A heparin-based nanoparticles with negative charge was fabricated by complementary strategy, which was expected to attain efficient uptake and simultaneously exert great anticancer activity.

METHODS

We synthesized heparin-based nanoparticles with targeting ligand folate and CPP ligand Tat to deliver paclitaxel (H-F-Tat-P NPs). The NPs were characterized by (1)H NMR, DLS and TEM, respectively. The effect of dual ligands on system behavior in aqueous solution was investigated. Moreover, its cellular internalization and anticancer activity were detected by flow cytometry, confocal microscopy and MTT.

RESULTS

Folate played a key role in the formation of heparin-based NPs dependent on the balance of amphiphilic Tat and hydrophobic folate. Although H-F-Tat-P NPs primarily entered FR specific and non-specific cells by similar routes, there were no comparability due to cell-type specific variation. Unlike non-specific cells, the complementary ligands could help negative-charged NPs to enhance cellular uptake facilitating its endosome escape in specific cells thereby exhibiting great anticancer activity.

CONCLUSIONS

The complementary strategy for negative-charged NPs was presented a promising delivery system for diverse anticancer agents enable simultaneously targeting and drug delivery.

Rational design of polyion complex nanoparticles to overcome cisplatin resistance in cancer therapy

Rationally designed PIC nanoparticles as next-generation delivery system: we have developed a core-shell-corona PIC nanoparticle (⊕) NP/Pt@PPC-DA as a next-generation delivery system. (⊕) NP/Pt@PPC-DA exhibits prolonged circulation and enhanced drug accumulation in tumors. Subsequently, tumor pH leads to the release of (⊕) NP/Pt, which facilitates cellular uptake followed by rapid intracellular cisplatin release. Using this delivery strategy cisplatin-resistant tumor growth in a murine xenograft model has been successfully suppressed.

Doxorubicin conjugate of poly(ethylene glycol)-block-polyphosphoester for cancer therapy

Polyphosphoesters with repeating phosphoester linkages in the backbone can be easily functionalized, are biodegradable and potentially biocompatible, and may be potential candidates as polymer carriers of drug conjugates. Here, the efficacy of a polyphosphoester drug conjugate as an anticancer agent in vivo is assessed for the first time. With controlled synthesis, doxorubicin conjugated to poly(ethylene glycol)-block-polyphosphoester (PPEH-DOX) via labile hydrazone bonds form spherical nanoparticles in aqueous solution with an average diameter of ≈60 nm. These nanoparticles are effectively internalized by MDA-MB-231 breast cancer cells and release the conjugated doxorubicin in response to the intracellular pH of endosomes and lysosomes, resulting in significant antiproliferative activity in cancer cells. Compared with free doxorubicin injection, PPEH-DOX injection exhibits much longer circulation behavior in the plasma of mice and leads to enhanced drug accumulation in tumor cells. In an MDA-MB-231 xenograft murine model, inhibition of tumor growth with systemic delivery of PPEH-DOX nanoparticles is more pronounced compared with free doxorubicin injection, suggesting the potential of polyphosphoesters as carriers of drug conjugates in cancer therapy.

Highly efficient hierarchical micelles integrating photothermal therapy and singlet oxygen-synergized chemotherapy for cancer eradication

It is highly desirable to develop theranostic nanoparticles for achieving cancer imaging with enhanced contrast and simultaneously multimodal synergistic therapy. Herein, we report a theranostic micelle system hierarchically assembling cyanine dye (indocyanine green) and chemotherapeutic compound (doxorubicin) (I/D-Micelles) as a novel theranostic platform with high drug loading, good stability and enhanced cellular uptake via clathrin-mediated endocytosis. I/D-Micelles exhibit the multiple functionalities including near-infrared fluorescence (NIRF), hyperthermia and intracellular singlet oxygen from indocyanine green, and simultaneous cytotoxicity from doxorubicin. Upon photoirradiation, I/D-Micelles can induce NIRF imaging, acute photothermal therapy via hyperthermia and simultaneous synergistic chemotherapy via singlet oxygen-triggered disruption of lysosomal membranes, eventually leading to enhanced NIRF imaging and superior tumor eradication without any re-growth. Our results suggest that the hierarchical micelles can act as a superior theranostic platform for cancer imaging and multimodal synergistic therapy.

25th anniversary article: interfacing nanoparticles and biology: new strategies for biomedicine

The exterior surface of nanoparticles (NPs) dictates the behavior of these systems with the outside world. Understanding the interactions of the NP surface functionality with biosystems enables the design and fabrication of effective platforms for therapeutics, diagnostics, and imaging agents. In this review, we highlight the role of chemistry in the engineering of nanomaterials, focusing on the fundamental role played by surface chemistry in controlling the interaction of NPs with proteins and cells.

Dynamic disordering of liposomal cocktails and the spatio-temporal favorable release of cargoes to circumvent drug resistance

Multidrug resistance (MDR) has been a major impediment to the success of cancer chemotherapy. Extensive efforts have been devoted to the development of drug delivery systems using nanotechnology to reverse MDR in cancer. However, the spontaneous release of drug payloads was always a slow process, which leads to the low intracellular drug concentration resulting in consequent drug insensitivity. To circumvent this limitation, we described a liposomal cocktail (LMDHV) constructed by a pH-responsive molecule (i.e., malachite green carbinol base (MG)) and liposome conjugated with Her-2 antibody for codelivery of doxorubicin (DOX) and verapamil (VER) to suppress drug resistance in Her-2 positive breast cancer. MG inserted in the bilayer as pH responders greatly contributed to the destabilization of the vesicle membrane in low pH, followed by the rapid release of the payloads. LMDHV showed 6-fold reversal efficiency in DOX resistant breast cancer owing to the efficient tumor targeting delivery and rapid burst release of drug intracellularly. Compared to tumor inhibition ratio of treated groups by free DOX (32.4 ± 7.4%), our designed kinetically favorable drug release system exhibited significantly (P < 0.01) enhanced tumor inhibition ratio up to 83.9 ± 12.5%, which is attributed to the remarkably increased drug concentration in cells. The spatio-temporal favorable release of drugs resulted in synergistic inhibition of tumor growth in xenografts. We envision that this new type of liposomal cocktail might be potentially utilized to circumvent drug resistance in the future.

Mitochondrial fragmentation is an important cellular event induced by ruthenium(II) polypyridyl complexes in osteosarcoma cells

A series of ruthenium(II) polypyridyl complexes were synthesized and evaluated for their in vitro anticancer activities. The results showed that ruthenium polypyridyl complexes, especially [Ru(bpy)2 (p-tFPIP)](2+) (2 a; bpy=bipyridine, tFPIP=2-(2-trifluoromethane phenyl)imidazole[4,5-f][1,10]phenanthroline), exhibited novel anticancer activity against human cancer cell lines, but with less toxicity to a human normal cell line. The results of flow cytometry and caspase activities analysis indicated that the 2 a-induced growth inhibition against MG-63 osteosarcoma cells was mainly caused by mitochondria-mediated apoptosis. DNA fragmentation and nuclear condensation as detected by TUNEL-DAPI co-staining further confirmed 2 a-induced apoptotic cell death. Further, fluorescence imaging revealed that ruthenium(II) polypyridyl complexes could target mitochondria to induce mitochondrial fragmentation, accompanied by depletion of mitochondrial membrane potential. Taken together, these findings suggest a potential application of theses ruthenium(II) complexes in the treatment of cancers.

Amplified plasmonic detection of DNA hybridization using doxorubicin-capped gold particles

We show in this article that doxorubicin-modified gold nanoparticles (Au NP-DOX) can be used for the post-amplification of the wavelength shift of localized surface plasmon resonance (LSPR) signals after DNA hybridization events. We take advantage of the intercalation properties of DOX with guanine-rich oligonucleotides and the plasmon coupling between surface-linked gold nanostructures and Au NP-DOX in solution to detect in a sensitive manner DNA hybridisation events. Post-treatment of double-stranded DNA with Au NP-DOX resulted in a detection limit of ≈600 pM, several times lower than that without post-incubation (LOD ≈ 40 nM).

Ultra-small gold nanoparticles synthesized in aqueous solution and their application in fluorometric collagen estimation using bi-ligand functionalization

Ultra-small hydrosol LBH-AuNPs were synthesized, and their application in the FRET based estimation of collagen investigated using bi-ligand functionalised LBH-AuNPs.

Direct synthesis of PEG-encapsulated gold nanoparticles using branched copolymer nanoreactors

A highly scalable approach to generating PEG-stabilized gold nanoparticles for biomedical applications using micelle-like branched copolymers as nanoreactors.

Biodegradable cationic polymeric nanocapsules for overcoming multidrug resistance and enabling drug-gene co-delivery to cancer cells

Having unique architectural features, cationic polymeric nanocapsules (NCs) with well-defined covalently stabilized biodegradable structures were generated as potentially universal and safe therapeutic nanocarriers. These NCs were synthesized from allyl-functionalized cationic polylactide (CPLA) by highly efficient UV-induced thiol-ene interfacial cross-linking in transparent miniemulsions. With tunable nanoscopic sizes, negligible cytotoxicity and remarkable degradability, they are able to encapsulate doxorubicin (Dox) with inner cavities and bind interleukin-8 (IL-8) small interfering RNA (siRNA) with cationic shells. The Dox-encapsulated NCs can effectively bypass the P-glycoprotein (Pgp)-mediated multidrug resistance of MCF7/ADR cancer cells, thereby resulting in increased intracellular drug concentration and reduced cell viability. In vitro studies also showed that the NCs loaded with Dox, IL-8 siRNA and both agents can be readily taken up by PC3 prostate cancer cells, resulting in a significant chemotherapeutic effect and/or IL-8 gene silencing.

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.

Undecylprodigiosin conjugated monodisperse gold nanoparticles efficiently cause apoptosis in colon cancer cells in vitro

Bacterial pigment undecylprodigiosin was conjugated to monodisperse gold nanoparticles, resulting in improved stability and cytotoxicity against colon cancer cells.

Insights into the adsorption of simple benzene derivatives on carbon nanotubes

This work characterizes the adsorption characteristics of simple benzene derivatives on carbon nanotubes.