Folate-encoded and Fe3O4-loaded polymeric micelles for dual targeting of cancer cells

Fluorescent magnetic nanoparticles with specific targeting functions for combinded targeting, optical imaging and magnetic resonance imaging

Superparamagnetic iron oxides nanoparticles possess specific magnetic properties to be an efficient contrast agent for magnetic resonance imaging (MRI) to enhance the detection and characterization of tissue lesions within the body. To endow specific properties to nanoparticles that can target cancer cells and prevent recognition by the reticuloendothelial system (RES), the surface of the nanoparticles was modified with folic-acid-conjugated poly(ethylene glycol) (FA-PEG). In this study, we investigated the multifunctional fluorescent magnetic nanoparticles (IOPFC) that can specifically target cancer cells and be monitored by both MRI and optical imaging. IOPFC consists of an iron oxide superparamagnetic nanoparticle conjugated with a layer of PEG, which was terminal modified with either Cypher5E or folic acid molecules. The core sizes of IOPFC nanoparticles are around 10 nm, which were visualized by transmission electron microscope (TEM). The hysteresis curves, generated with superconducting quantum interference device (SQUID) magnetometer analysis, demonstrated that IOPFC nanoparticles are superparamagnetic with insignificant hysteresis. IOPFC displays higher intracellular uptake into KB and MDA-MB-231 cells due to the over-expressed folate receptor. This result is confirmed by laser confocal scanning microscopy (LCSM) and atomic flow cytometry. Both in vitro and in vivo MRI studies show better IOPFC uptake by the KB cells (folate positive) than the HT1080 cells (folate negative) and, hence, stronger T 2-weighted signals enhancement. The in vivo fluorescent image recorded at 20 min post injection show strong fluorescence from IOPFC which can be observed around the tumor region. This multifunctional nanoparticle can assess the potential application of developing a magnetic nanoparticle system that combines tumor targeting, as well as MRI and optical imaging.

Enhanced cell uptake of superparamagnetic iron oxide nanoparticles through direct chemisorption of FITC-Tat-PEG₆₀₀-b-poly(glycerol monoacrylate)

Magnetic nanoparticles (MNPs) functionalized with specific ligands are emerging as a highly integrated platform for cancer targeting, drug delivery, and magnetic resonance imaging applications. In this study, we describe a multifunctional magnetic nanoparticle system (FITC-Tat MNPs) consisting of a fluorescently labeled cell penetrating peptide (FITC-Tat peptide), a biocompatible block copolymer PEG(600)-b-poly(glycerol monoacrylate) (PEG(600)-b-PGA), and a superparamagnetic iron oxide (SPIO) nanoparticle core. The particles were prepared by direct chemisorption of PEG(600)-b-PGA conjugated with FITC-Tat peptide on the SPIO nanoparticles. FITC-MNPs without Tat were prepared for comparison. Flow cytometry assays revealed significantly higher uptake of FITC-Tat MNPs compared to FITC-MNPs in Caco-2 cells. These results were confirmed using confocal laser scanning microscopy (LSCM), which further demonstrated that the FITC-Tat MNPs accumulated in the cytoplasm and nucleus while the FITC-MNPs were localized in the cell membrane compartments. The FITC-Tat MNPs did not exhibit observable cytotoxicity in MTS assays.

Hydrotropic magnetic micelles for combined magnetic resonance imaging and cancer therapy

Polymeric nanoparticles, capable of encapsulating imaging agents and therapeutic drugs, have significant advantages for simultaneous diagnosis and therapy. Nonetheless, improvements in the loading contents of the active agents are needed to achieve enhanced imaging and effective therapeutic outcomes. Aiming to make these improvements, a hydrotropic micelle (HM) was explored to encapsulate superparamagnetic iron oxide nanoparticles (SPIONs) as the magnetic resonance (MR) imaging agent and paclitaxel (PTX) as the hydrophobic anticancer drug. Owing to its hydrotropic inner core with hydrophobic nature, HM could effectively encapsulate both of PTX and SPION via the simple dialysis method. The hydrodynamic size of HM increased from 68 to 178nm after physical encapsulation of SPION and PTX. Transmission electron microscopy analysis of HM bearing SPION and PTX (HM-SPION-PTX) revealed a spherical morphology with SPION clusters in the micelle cores. The micelles released PTX in a sustained manner. The bare HM and HM-SPION showed no toxicity to SCC7 cells, whereas HM-PTX and HM-SPION-PTX showed dose-dependent cytotoxicity that was lower than free PTX. HM-SPION-PTX exhibited 8.1-fold higher T(2) relaxivity than HM-SPION, implying potential of HM-SPION-PTX as the contrast agent for MR imaging. When systemically administered to tumor-bearing mice, HM-SPION-PTX was effectively accumulated at the tumor site, allowing its detection using MR imaging and effective therapy. Overall, these results suggested that HM-SPION-PTX is a promising candidate for combined diagnosis and treatment of cancer.

Novel superparamagnetic iron oxide nanoparticles for tumor embolization application: preparation, characterization and double targeting

The goal of this study was to develop novel embolic nanoparticles for targeted tumor therapy with dual targeting: magnetic field-guided and peptide-directed targeting. The embolic nanoparticles SP5.2/tTF-OCMCs-SPIO-NPs were prepared by surface-modifying of superparamagnetic iron oxide nanoparticles (SPIO-NPs) with o-carboxymethylchitosans (OCMCs) and SP5.2/tTF (SP5.2: a peptide binding to VEGFR-1; tTF: truncated tissue factor) to improve their stability and to target over-expressing VEGFR-1 cells. The physicochemical characterization results showed that the OCMCs-SPIO-NPs have a spherical or ellipsoidal morphology with an average diameter of 10-20 nm. And they possess magnetism with a saturation magnetization of 66.1 emu/g, negligible coercivity and remanence at room temperature. In addition, the confocal microscopy, Prussian blue staining and FX activation analysis respectively demonstrated the peptide-directed targeting, magnetic field-guided targeted and blood coagulation activity of the SP5.2/tTF-OCMCs-SPIO-NPs. These properties separately belong to SP5.2, Fe(3)O(4) and tTF moieties of the SP5.2/tTF-OCMCs-SPIO-NPs. Thus these SP5.2/tTF-OCMCs-SPIO-NPs with double-targeting function should have a potential application in embolization therapy of tumor blood vessels.

Targeting EGFR-overexpressing tumor cells using Cetuximab-immunomicelles loaded with doxorubicin and superparamagnetic iron oxide

Epidermal growth factor receptor (EGFR), a cellular transmembrane receptor, plays a key role in cell proliferation and is linked to a poor prognosis in various human cancers. In this study, we constructed Cetuximab-immunomicelles in which the anti-EGFR monoclonal antibody was linked to poly(ethylene glycol)-block-poly(ɛ-caprolactone) (PEG-PCL) nanomicelles that were loaded with doxorubicin (DOX) and superparamagnetic iron oxide (SPIO). The specific interactions between EGFR-overexpressing tumor cells (A431) and immunomicelles were observed using confocal laser scanning microscopy (CLSM) and flow cytometry. Furthermore, the capacity of transporting SPIO into tumor cells using these immunomicelles was evaluated with a 1.5 T clinical magnetic resonance imaging (MRI) scanner. It was found that the acquired MRI T2 signal intensity of A431 cells that were treated with the SPIO-loaded and antibody-functionalized micelles decreased significantly. Using the thiazolyl blue tetrazolium bromide (MTT) assay, we also demonstrated that the immunomicelles inhibited cell proliferation more effectively than their nontargeting counterparts. Our results suggest that Cetuximab-immunomicelles are a useful delivery vehicle for DOX and SPIO to EGFR-overexpressing tumor cells in vitro and that Cetuximab-immunomicelles can serve as a MRI-visible and targeted drug delivery agent for better tumor imaging and therapy.

Squalene based nanocomposites: a new platform for the design of multifunctional pharmaceutical theragnostics

This study reports the design of a novel theragnostic nanomedicine which combines (i) the ability to target a prodrug of gemcitabine to an experimental solid tumor under the influence of a magnetic field with (ii) the imaging of the targeted tumoral nodule. This concept is based on the inclusion of magnetite nanocrystals into nanoparticles (NPs) constructed by self-assembling molecules of the squalenoyl gemcitabine (SQgem) bioconjugate. The nanocomposites are characterized by an unusually high drug loading, a significant magnetic susceptibility, and a low burst release. When injected to the L1210 subcutaneous mice tumor model, these magnetite/SQgem NPs were magnetically guided, and they displayed considerably greater anticancer activity than the other anticancer treatments (magnetite/SQgem NPs nonmagnetically guided, SQgem NPs, or gemcitabine free in solution). The histology and immunohistochemistry investigation of the tumor biopsies clearly evidenced the therapeutic superiority of the magnetically guided nanocomposites, while Prussian blue staining confirmed their accumulation at the tumor periphery. The superior therapeutic activity and enhanced tumor accumulation has been successfully visualized using T(2)-weighted imaging in magnetic resonance imaging (MRI). This concept was further enlarged by (i) the design of squalene-based NPs containing the T(1) Gd(3+) contrast agent instead of magnetite and (ii) the application to other anticancer squalenoyls, such as, cisplatin, doxorubicin, and paclitaxel. Thus, by combining different anticancer medicines as well as contrast imaging agents in NPs, we open the door toward generic conceptual framework for cancer treatment and diagnosis. This new theragnostic nanotechnology platform is expected to have important applications in cancer therapy.

Active targeting of cancer cells using folic acid-conjugated platinum nanoparticles

Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized via reduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 μg ml(-1) for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.

Preparation, stability and cytocompatibility of magnetic/PLA-PEG hybrids

Hybrid nanocolloids based on biodegradable polymers of poly(lactide) (PLA) or poly(lactide)-block-poly(ethylene glycol) (PLA-PEG) and hydrophobic iron oxide magnetic nanoparticles (MNPs) of ca. 5 nm are prepared via a self-assembly route. The magnetic nanoparticles are organized in superclusters inside the hydrophobic core of PLA-PEG micelles or cholate-stabilized PLA nanospheres. The hydrodynamic diameter of MNPs-loaded PLA nanospheres is approximately 250 nm, whereas that of MNPs-loaded PLA-PEG micelles is much lower (approximately 100 nm) and thus compatible with applications where prolonged blood circulation is required. The PLA-PEG micelles exhibit high encapsulation efficiency for the MNPs, imparting a saturation magnetization value to the hybrid of 8.4 emu g(-1). Both hybrid colloids display magnetic properties of a non-interacting assembly of superparamagnetic particles and a low blocking temperature, both of which are key attributes for colloidally stable ferrofluids. Furthermore, the PLA-PEG magnetic hybrids display remarkable colloidal stability at high ionic strength, temperature and in human blood plasma, while the estimated critical micelle concentration of ca. 2 x 10(-5) mM (0.3 mg L(-1)) indicates the low probability of the colloids dissociation in the blood compartment. They were also found to be non-toxic to human cells in vitro. The results underline the potential of the magnetic/PLA-PEG hybrids and encourage further research for their in vivo biomedical applications.

Multilayer nanoparticles with a magnetite core and a polycation inner shell as pH-responsive carriers for drug delivery

Nanocarriers with multilayer core-shell architecture were prepared by coating a superparamagnetic Fe(3)O(4) core with a triblock copolymer. The first block of the copolymer formed the biocompatible outermost shell of the nanocarrier. The second block that contains amino groups and hydrophobic moiety formed the inner shell. The third block bound tightly onto the Fe(3)O(4) core. Chlorambucil (an anticancer agent) and indomethacin (an anti-inflammation agent), each containing a carboxyl group and a hydrophobic moiety, were loaded into the amino-group-containing inner shell by a combination of ionic and hydrophobic interactions. The release rate of the loaded drugs was slow at pH 7.4, mimicking the blood environment, whereas the release rate increased significantly at acidic pH, mimicking the intracellular conditions in the endosome/lysosome. This can be attributed to the disruption of the ionic bond caused by protonation of the carboxylate anion of the drugs and the swelling of the inner shell caused by protonation of the amino groups.

Micellar carrier based on methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) block copolymers bearing ketone groups on the polyester block for doxorubicin delivery

Block copolymers of Methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) bearing ketone groups (MPEG-b-P(CL-co-OPD)) are synthesized and evaluated for its potential to form micelles containing doxorubicin (DOX), a representative anticancer drug, by using an in vitro method based on membrane dialysis to emulate drug release in vivo. The (1)H NMR spectra of the prepared block copolymers in D(2)O solution exhibit peaks due to the P(OPD-co-CL) in decreased intensity, indicates that the polymers form micelle particles containing the hydrophilic segments in their external parts. The CMC of the copolymer decrease with an increase in the content of ketone groups in the hydrophobic chain. Drug-free and drug-loaded solutions of structurally related copolymers indicate the polymeric aggregation into micellar-type constructs. The size of the drug-loaded micelles is found to be larger than corresponding drug-free micelles. The release rate of MPEG-b-PCL micelles is faster than MPEG-b-P(OPD-co-CL) micelles in pH 7.4 buffered solution and they have a similar release rate in pH 5.0 buffered solution. This study, therefore, confirms the potential of a novel functional block copolymers, Methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) bearing ketone Groups, for the formation of polymeric micelles for drug delivery.

Stimulus-responsive targeted nanomicelles for effective cancer therapy

Emerging nanotechnology has already developed various innovative nanomedicines. Nanomicelles, self-assemblies of block copolymers, are promising nanomedicines for targeted drug delivery and imaging. Stimulus-responsive targeted nanomicelles are designed to release drugs based on stimuli such as pH, temperature, redox potential, magnetism and ultrasound. This article will focus on recent advancements in the design of stimulus-responsive targeted nanomicelles loaded with anticancer drugs to fulfill the challenges associated with cancer cells (e.g., multidrug resistance) for the effective treatment of cancer. The significant toxicity issues and a possible future perspective associated with nanomicelles are also discussed here.

Review on supermolecules as chemical drugs

Supramolecular medicinal chemistry field has been a quite rapidly developing, increasingly active and newly rising interdiscipline which is the new expansion of supramolecular chemistry in pharmaceutical sciences, and is gradually becoming a relatively independent scientific area. Supramolecular drugs could be defined as medicinal supermolecules formed by two or more molecules through non-covalent bonds. So far a lot of supermolecules as chemical drugs have been widely used in clinics. Supermolecules as chemical drugs, i.e. supramolecular chemical drugs or supramolecular drugs, which might have the excellences of lower cost, shorter period, higher potential as clinical drugs for their successful research and development, may possess higher bioavailability, better biocompatibility and drug-targeting, fewer multidrug-resistances, lower toxicity, less adverse effect, and better curative effects as well as safety, and therefore exhibit wide potential application. These overwhelming advantages have drawn enormous special attention. This paper gives the definition of supramolecular drugs, proposes the concept of supramolecular chemical drugs, and systematically reviews the recent advances in the research and development of supermolecules, including organic and inorganic complex ones as chemical drugs in the area of antitumor, anti-inflammatory, analgesic, antimalarial, antibacterial, antifungal, antivirus, anti-epileptic, cardiovascular agents and magnetic resonance imaging agents and so on. The perspectives of the foreseeable future and potential application of supramolecules as chemical drugs are also presented.

Targeted nanomedicines: effective treatment modalities for cancer, AIDS and brain disorders

Novel technology in the nanomedicine field is expected to develop innovative products as targeted drug-delivery approaches. Targeted drug delivery of various drugs for the treatment of cancer, AIDS and brain disorders is the primary research area in which nanomedicines have a major role and need. This review is concerned with emerging targeted nanomedicines (polymeric nanoparticles, solid lipid nanoparticles, polymeric micelles, dendrimers, liposomes, gold nanoparticles and magnetic nanoparticles) and multifunctional carriers capable of combining targeted drug delivery and imaging (polymeric micelles, dendrimers and magnetic nanoparticles) in the field of pharmaceutical applications. The significant toxicity issues associated with these nanomedicines are also explored here.