Tumor-targeted polydiacetylene micelles for in vivo imaging and drug delivery

Light-Induced Self-Assembled Polydiacetylene/Carbon Dot Functional "Honeycomb"

The design of functional supramolecular assemblies from individual molecular building blocks is a fundamental challenge in chemistry and material science. We report on the fabrication of "honeycomb" films by light-induced coassembly of diacetylene derivatives and carbon dots. Specifically, modulating noncovalent interactions between the carbon dots, macrocyclic diacetylene, and anthraquinone diacetylene facilitates formation of thin films exhibiting a long-range, uniform pore structure. We show that light irradiation at distinct wavelengths plays a key role in the assembly process and generation of unique macro-porous morphology, by both initiating interactions between the carbon dots and the anthraquinone moieties and giving rise to the topotactic polymerization of the polydiacetylene network. We further demonstrate utilization of the macro-porous film as a photocatalytic platform for water pollutant degradation and as potential supercapacitor electrodes, both applications taking advantage of the high surface area, hydrophobicity, and pore structure of the film.

Tumor-Targeted Perfluorinated Micelles as Efficient Theranostic Agents Combining Positron Emission Tomography and Radiosensitization

We report the synthesis of biocompatible perfluorinated micelles designed to improve radiotherapeutic efficacy in a radioresistant tumor environment. In vitro and in vivo behaviors of perfluorinated micelles were assessed at both cellular and tissular levels. The micellar platform offers key advantages as theranostic tool: (i) small size, allowing deep tissue penetration; (ii) oxygen transport to hypoxic tissues; (iii) negligible toxicity in the absence of ionizing radiation; (iv) internalization into cancer cells; (v) potent radiosensitizing effect; and (vi) excellent tumor-targeting properties, as monitored by positron emission tomography. We have demonstrated strong in vitro radiosensitizing effects of the micelle and in vivo tumor targeting, making this nanometric carrier a promising tool for the potentiation of focused radiotherapy.

Phototriggered Cytotoxicity of Ferrocene-Based Micelles - A Nonconventional Approach to Phototherapy

We report the design, synthesis, and in vitro evaluation of stimuli-responsive nanoscale micelles that can be activated by light to induce a cytotoxic effect. Micelles were assembled from amphiphilic units made of a photoactivatable ferrocenyl linker, connected on one side to a lipophilic chain, and on the other side to a hydrophilic pegylated chain. In vitro experiments indicated that pristine micelles ("off" state) were nontoxic to MCF-7 cancer cells, even at high concentrations, but became potent upon photoactivation ("on" state). The illumination process led to the dissociation of the micelles and the concomitant release of iron species, triggering cytotoxicity.

Targeted delivery of LXR-agonists to atherosclerotic lesions mediated by polydiacetylene micelles

We report the development of compact and stabilized micelles incorporating a synthetic LXR agonist prodrug for the passive targeting of atherosclerotic lesions and therapeutic intervention. In vivo studies showed that the nanohybrid micelles exhibited favorable pharmacokinetics/biodistribution and were able to upregulate, to some extent, LXR target genes with no alteration of lipid metabolism.

Proteinic Artificial Skin with Molecularly Encoded Coloration

An ability to integrate adaptive coloration and tissue-like compositions, structures, as well as mechanical properties, and so forth into a material remains elusive. To address this problem, this work presents a solution whereby these features were integrated into a proteinic artificial skin through biomimetic design. In this artificial skin, silk fibroin was used to mimic the structural framework of the cytoskeleton due to its unique molecular network structure and outstanding and tunable mechanical properties. Meanwhile, a thermochromic filamentous network consisting of C₂₅-GAGAGAGY amphiphilic peptides was designed to mimic the functional tracks in the cytoskeleton, enabling its temperature-adaptive coloration ability. The interconnected linkage between the structural frame and functional units makes this artificial skin have stable structures, mechanical properties, and functions. The whole protein composition also makes this artificial skin essentially different from other existing color-tunable artificial skins, which are a combination of organic and inorganic compounds. Furthermore, because the protein composition is compatible with a range of dyes, the chromatic gamut of adaptive coloration of the developed artificial skin can be further expanded by color fusion. With the further inclusion of other functional units, such as photothermal and magnetothermal nanoparticles, the thermochromism of the artificial skin could be realized through sun exposure and alternating magnetic field modulation. With this diversity in color change pathways and stimulation mode, as well as the environmental friendliness of the material used, these artificial proteinic skins have promising applications as sensors in physiological monitoring, food preservation, and anti-counterfeiting.

Dynamic self-assembly of mannosylated-calix[4]arene into micelles for the delivery of hydrophobic drugs

Carbohydrate-lectin interactions and glycol-molecule-driven self-assembly are powerful yet challenging strategies to create supramolecular nanostructures for biomedical applications. Herein, we develop a modular approach of micellization with a small molecular mannosylated-calix[4]arene synthetic core, CA₄-Man3, to generate nano-micelles, CA₄-Man3-NPs, which can target cancer cell surface receptors and facilitate the delivery of hydrophobic cargo. The oligomeric nature of the calix[4]arene enables the dynamic self-assembly of calix[4]arene (CA₄), where an amphiphile, functionalized with mannose units (CA-glycoconjugates) in the upper rim and alkylated lower rim, afforded the CA₄-Man3-NPs in a controllable manner. The presence of thiourea units between calixarene and tri-mannose moiety facilitated the formation of a stable core with bidentate hydrogen bonds, which in turn promoted mannose receptor targeted uptake and helped in the intracellular pH-responsive release of antineoplastic doxorubicin (Dox). Physiochemical features including the stability of the nanomicelle could circumvent the undesirable leakage of the cargoes, ensuring maximum therapeutic output with minimum off-targeted toxicity. Most importantly, surface-enhanced Raman scattering (SERS) was utilized for the first time to evaluate the critical micelle concentration during the formation, cellular uptake and intracellular drug release. The present study not only provides an architectural design of a new class of organic small molecular nanomicelles but also unveils a robust self-assembly approach that paves the way for the delivery of a wide range of hydrophobic chemotherapeutic drugs.

Modifying Polydiacetylene Vesicle Compositions to Reduce Non-Specific Interactions

Polydiacetylene (PDA) vesicles provide useful stimuli-responsive behavior as well as by the modular structure afford a means for the design of sensing and delivery systems with tunable target specificity. To reduce inherent non-specific interaction with either anionic or cationic formulations of polydiacetylene vesicles, we explored the use of various lengths of poly(ethylene glycol) (PEG) amphiphiles for integration and polymerization within PDA vesicles. Our results established that as little as 1% of polyethylene glycol amphiphile integration into anionic vesicles was sufficient to significantly reduce non-specific association with mammalian cells. Similarly integrating a low percent of PEG amphiphile content within cationic vesicles could also significantly reduce non-specific cell association, and moreover reduced cytotoxicity. These results may be prove useful in augmenting PDA vesicles formulations for reduced non-specific interaction which is of particularly interest to enhancing selectivity in vesicles designed with integrated targeting moieties for sensing and drug delivery applications.

Tumor-targeted superfluorinated micellar probe for sensitive in vivo19F-MRI

We describe herein the assembly and in vivo evaluation of a tailor-made micellar carrier system designed for the optimized encapsulation of a superfluorinated MRI probe and further targeting of solid tumors. The in vivo validation was carried out on MC38 tumor-bearing mice which allowed the confirmation of the efficient targeting properties of the nano-carrier, as monitored by 19F-MRI.

Tuning the Surface Charge of Self-Assembled Polydiacetylene Vesicles to Control Aggregation and Cell Binding

Polydiacetylene vesicles of various compositions were assembled using a two-part mixture of 10,12-pentacosadiynoic acid (PCDA) and ethylenedioxy-bis-ethylamine (EDEA)-labeled PCDA in order to control surface charge and stability within a desired pH range. Investigation of the interaction of the vesicles with mammalian cells as a function of surface charge was carried out and identified a clear correlation in cell–vesicle association and corresponding cell death for vesicles with positive surface charge. The binding behavior of the vesicles was found to be tunable by regulating the proportion of anionic PCDA relative to cationic PCDA–EDEA content within vesicles as to control the surface charge as a function of pH. Association of vesicles with cells thus depended on the corresponding charge of the vesicles and cell surface. The prospect of this work may serve as a step toward future vesicle designs to allow triggered uptake of vesicles locally within low pH tumor microenvironments.

Polydiacetylene-Perylenediimide Supercapacitors

Organic supercapacitors have attracted interest as promising "green" and efficient components in energy storage applications. A polydiacetylene derivative coupled with reduced graphene oxide was employed, for the first time, to generate an organic pseudocapacitance-based supercapacitor that exhibited excellent electrochemical properties. Specifically, diacetylene monomers were functionalized with perylenediimide (PDI), spontaneously forming elongated microfibers. Following polymerization through UV irradiation, the PDI-polydiacetylene microfibers were interspersed with reduced graphene oxide (rGO), generating a porous electrode material exhibiting a high surface area and facilitating efficient ion diffusion, both essential preconditions for supercapacitor applications. We show that PDI-polydiacetylene has an important role in enhancing the electrochemical properties as a supercapacitor electrode. Besides stabilizing the microporous electrode organization, the delocalized π electrons in both the PDI residues and conjugated network of the polydiacetylene contributed to a significantly higher capacitance (specific capacitance >600 F g^-1 at 1 A g^-1 current density), longer discharge time, and high power density. The PDI-polydiacetylene-rGO electrodes were employed in a functional supercapacitor device.

Nanotoxicology at the particle/micelle frontier: influence of core-polymerization on the intracellular distribution, cytotoxicity and genotoxicity of polydiacetylene micelles

The understanding of the cellular uptake and the intracellular fate of nanoparticles and their subsequent influence on cell viability is challenging as far as micelles are concerned. Such systems are dynamic by nature, existing as unimers under their critical micelle concentration (CMC), and as micelles in equilibrium with unimers above the CMC, making canonical dose-response relationships difficult to establish. The purpose of this study was to investigate the in vitro cytotoxicity and uptake of two micellar sytems that are relevant for drug delivery. The two micelles incorporate a poly(ethylene glycol) coating and a pentacosadiynoic core which is either polymerized (pDA-PEG micelles) or non-polymerized (DA-PEG micelles), with the aim of evaluating the influence of the micelles status ("particle-like" or "dynamic", respectively) on their toxicological profile. Intracellular distribution and cytotoxicity of polymerized and non-polymerized micelles were investigated on RAW 264.7 macrophages in order to compare any different interactions with cells. Non-polymerized micelles showed significantly higher cytotoxicity than polymerized micelles, especially in terms of cell permeabilization, correlated to a higher accumulation in cell membranes. Other potential toxicity endpoints of polymerized micelles were then thoroughly studied in order to assess possible responses resulting from their endocytosis. No specific mechanisms of cytotoxicity were observed, neither in terms of apoptosis induction, cell membrane damage, release of inflammatory mediators nor genotoxicity. These data indicate that non-polymerized micelles accumulate in the cell membrane and induce cell membrane permeabilization, resulting in significant toxicity, whereas polymerized, stable micelles are internalized by cells but exert no or very low toxicity.

Tuning the cationic interface of simple polydiacetylene micelles to improve siRNA delivery at the cellular level

Polydiacetylene micelles were assembled from four different cationic amphiphiles and photopolymerized to reinforce their architecture. The produced micelles were systematically investigated, in interaction with siRNAs, for intracellular delivery of the silencing nucleic acids. The performances of the carrier systems were rationalized based on the cell penetrating properties of the micelles and the nature of their cationic complexing group, responsible for efficient siRNA binding and further endosomal escape.

Fibrin-Targeted Polymerized Shell Microbubbles as Potential Theranostic Agents for Surgical Adhesions

The development of new therapies for surgical adhesions has proven to be difficult as there is no consistently effective way to assess treatment efficacy in clinical trials without performing a second surgery, which can result in additional adhesions. We have developed lipid microbubble formulations that use a short peptide sequence, CREKA, to target fibrin, the molecule that forms nascent adhesions. These targeted polymerized shell microbubbles (PSMs) are designed to allow ultrasound imaging of early adhesions for diagnostic purposes and for evaluating the success of potential treatments in clinical trials while acting as a possible treatment. In this study, we show that CREKA-targeted microbubbles preferentially bind fibrin over fibrinogen and are stable for long periods of time (∼48 h), that these bound microbubbles can be visualized by ultrasound, and that neither these lipid-based bubbles nor their diagnostic-ultrasound-induced vibrations damage mesothelial cells in vitro. Moreover, these bubbles show the potential to identify adhesionlike fibrin formations and may hold promise in blocking or breaking up fibrin formations in vivo.

Effect of polydiacetylene-based nanosomes on cell viability and endocytosis

Polydiacetylene-based nanoparticles have been developed as nanocarriers for various bio-applications. However, how nanocarriers enter the cell environment and affect cell viability has not yet been considerably explored. In this study, polydiacetylene-based nanoliposomes (nanosomes) were electrostatically complexed with rhodamine fluorophores. Based on real-time cell imaging and cell viability assessment, the most highly polymerized nanosomes were found to be less toxic to cells. Moreover, it was revealed that the rhodamine/polydiacetylene nanosome complex dissociates at cell environment, the polydiacetylene nanosome penetrates into cells, as suggested by the fluorescence observed in confocal microscopy images.

Design and evaluation of ionizable peptide amphiphiles for siRNA delivery

Small interfering RNAs (siRNAs) can down-regulate the expression of a target mRNA molecule in a sequence-specific manner, making them an attractive new class of drugs with broad potential for the treatment of diverse human diseases. Here, we report the synthesis of a series of cationic amphiphiles which were obtained by the coupling of amino acids and dipeptides onto a lipidic double chain. The new amphiphiles presenting a peptidic motif on a short hydrophilic spacer group were evaluated for selective gene silencing through RNA interference. Our results show that tryptophan residues boost siRNA delivery in an unexpected manner. The silencing experiments performed with very low concentrations of siRNA showed that the best formulations could induce significant death of tumor cells after silencing of polo-like kinase 1 which is implicated in cell cycle progression. In addition, these Trp containing peptide amphiphiles were highly efficient siRNA delivery vectors even in presence of competing serum proteins.

Tumor targeted micellar nanocarriers assembled from epipodophyllotoxin-based amphiphiles

Micelle-forming amphiphilic drug conjugates were synthesized starting from a biologically active epipodophyllotoxin derivative which was covalently inserted in between a hydrophilic PEG unit and a hydrophobic stearyl chain. The epipodophyllotoxin-containing amphiphiles were assembled into the corresponding micelles which were evaluated in vivo for their tumor targeting properties.

Covalently Linked Perylene Diimide-Polydiacetylene Nanofibers Display Enhanced Stability and Photocurrent with Reversible FRET Phenomenon

Because of their unique structural and optical properties, 1D perylene diimide (PDI) derivatives have gained attention for use in optoelectronic devices. However, PDI-containing self-assembled supramolecular systems often are of limited use because they have supramolecular architectures that are held together by weak noncovalent π-π stacking, hydrogen bonding, and hydrophobic interactions. As a result, they are intrinsically unstable under solution-processing conditions. To overcome this limitation, a polydiacetylene (PDA)-based strategy is developed to construct a solvent-resistant and stable PDI assembly. For this purpose, first the monomer PDI-BisDA is generated, in which two polymerizable diacetylene (DA) units are covalently linked to a PDI core. Importantly, 254 nm UV irradiation of self-assembled PDI-BisDA nanofibers forms solvent-resistant and stable PDI-PDA fibers. Owing to the presence of PDA, the generated polymer fibers display an increased photocurrent. In addition, the existence of PDA and PDI moieties in the fiber leads to the occurrence of switchable on-off fluorescence resonance energy transfer (FRET) between the PDI and reversibly thermochromic PDA chromophores.

Aptamer-decorated polydiacetylene micelles with improved targeting of cancer cells

In this study, a "click and hybridization" strategy was developed for the functionalization of polydiacetylene micelles with a targeting aptamer ligand. Decoration of the nanocarriers with an anti-Annexin A2 sequence efficiently triggered enhanced internalization of the functionalized micelles in the MCF-7 cell line, with a marked increase compared to control micelles.

Light-Cross-linked Enediyne Small-Molecule Micelle-Based Drug-Delivery System

Light-cross-linked small-molecule micelles with enediyne units are designed for developing efficient drug-delivery systems. Gemcitabine (GEM) is chosen as a model hydrophilic drug and tethered with a maleimide-based enediyne (EDY) as a hydrophobic tail in the preparation of amphiphilic EDY-GEM. The stable micellar particles are obtained by cross-linking the enediyne moieties via photoinduced Bergman cyclization polymerization in aqueous media. The light-cross-linked spherical micelles with a size of 80 nm are characterized with dynamic light scattering and electron microscopy, showing robust micellar stability, bright fluorescent emission due to their intrinsic conjugated structure, and potential passive tumor-targeting ability through the enhanced permeability and retention effect. The drug-loaded micelles, as an example of light-cross-linked small-molecule micelle-based drug-delivery system, exhibit high drug-loading contents (50%) and greatly improved cytotoxicity toward A549 cells (decreasing the IC₅₀ value of Gemcitabine by 10 times), thanks to the greatly increased cellular uptake of the drug-loaded micelles as confirmed by confocal laser scanning microscopy. The light-cross-linked enediyne-based small-molecule micelles system therefore provides a simple yet efficient drug-delivery platform for cancer chemotherapy.

Polyamine transport system-targeted nanometric micelles assembled from epipodophyllotoxin-amphiphiles

Micelle-forming amphiphilic drug conjugates were synthesized starting from a biologically active epipodophyllotoxin derivative which was covalently inserted in between a hydrophilic targeting spermine unit, and a hydrophobic stearyl chain.

The Hydrophobic Effect Applied to Organic Synthesis: Recent Synthetic Chemistry "in Water"

Recent developments over the past few years in aqueous micellar catalysis are discussed. Applications to problems in synthesis are highlighted, enabled by the use of surfactants that self-aggregate in water into micelles as nanoreactors. These include amphiphiles that have been available for some time, as well as those that have been newly designed. Reactions catalyzed by transition metals, including Pd, Cu, Rh, and Au, are of particular focus.

Polydiacetylenic nanofibers as new siRNA vehicles for in vitro and in vivo delivery

Polydiacetylenic nanofibers (PDA-Nfs) obtained by photopolymerization of surfactant 1 were optimized for intracellular delivery of small interfering RNAs (siRNAs). PDA-Nfs/siRNA complexes efficiently silenced the oncogene Lim-1 in the renal cancer cells 786-O in vitro. Intraperitoneal injection of PDA-Nfs/siLim1 downregulated Lim-1 in subcutaneous tumor xenografts obtained with 786-O cells in nude mice. Thus, PDA-Nfs represent an innovative system for in vivo delivery of siRNAs.

Co-delivery of anti-PLK-1 siRNA and camptothecin by nanometric polydiacetylenic micelles results in a synergistic cell killing

Recently, it has been shown that the efficiency of antitumoral drugs can be enhanced when combined with therapeutic siRNAs. In the present study, an original platform based on polydiacetylenic micelles containing a cationic head group able to efficiently deliver a small interfering RNA (siRNA) targeting the PLK-1 gene while offering a hydrophobic environment for encapsulation of lipophilic drugs such as camptothecin is developed. We demonstrate that the co-delivery of these two agents with our micellar system results in a synergistic tumor cell killing of cervical and breast cancer cell lines in vitro. The combined drugs are active in a subcutaneous in vivo cancer model. Altogether, the results show that our nanometric micellar delivery system can be used for the development of new drug–siRNA combo-therapies.

Recently, it has been shown that the efficiency of antitumoral drugs can be enhanced when combined with therapeutic siRNAs.

Biotin-functionalized targeted polydiacetylene micelles

Polydiacetylene micelles were functionalized with controlled amounts of biotin using bioorthogonal click chemistry.

Mode of PEG Coverage on Carbon Nanotubes Affects Binding of Innate Immune Protein C1q

Surface modification of nanoparticles with poly(ethylene glycol) (PEG) is used in biomedicine to increase the circulation time of the particles after intravenous injection. Here, we study the interaction of PEG-covered carbon nanotubes (CNTs) with the serum complement protein C1q. Besides being the target-recognizing unit of the initiating complex for the classical pathway of complement in our innate immune system, C1q is involved in a range of important physiological processes. We modified the surface of multiwalled CNTs with covalently grafted PEG and physically adsorbed PEG. Transmission electron microscopy revealed the interaction of these PEG-coated CNTs with C1q. We found abundant C1q coverage on the PEG-grafted CNTs but not on the CNTs with adsorbed PEG. We tested the ability of these CNTs to activate the complement system using in vitro complement activation assays. None of the CNTs studied activated the C1q-dependent classical complement pathway. These findings are pertinent to the safe design and novel biomedical applications of PEGylated CNTs.

pH-Responsive Nanometric Polydiacetylenic Micelles Allow for Efficient Intracellular siRNA Delivery

A novel generation of pH-responsive photopolymerized diacetylenic amphiphile (PDA) micelles with a diameter of 10 nm was designed and optimized for the intracellular delivery of siRNAs. Dialysis and photopolymerization of the micelles allowed a strong reduction of the cytotoxicity of the nanovector, while the hydrophilic histidine headgroup permitted enhancing the siRNA delivery potential by improving the endosomal escape via imidazole protonation. These PDA-micellar systems were fully characterized by DLS, TEM, and DOSY-NMR experiments. The resulting bioactive complexes of PDA-micelles with siRNA were shown to have an optimal size below 100 nm.

A Magnetically Responsive Polydiacetylene Precursor for Latent Fingerprint Analysis

A magnetically responsive diacetylene (DA) powder was developed for the visualization of latent fingerprints. A mixture of the DA and magnetite nanoparticles, applied to a surface containing latent fingermarks, becomes immobilized along the ridge patterns of the fingerprints when a magnetic field is applied. Alignment along the ridge structures is a consequence of favorable hydrophobic interactions occurring between the long alkyl chains in the DAs and the lipid-rich, sebaceous latent fingermarks. UV irradiation of the DA-magnetite composite immobilized on the latent fingerprint results in the generation of blue-colored PDAs. Heat treatment of the blue-colored image promotes a blue-to-red transition as well as fluorescence turn-on. A combination of the aligned pale brown-colored monomeric state, UV irradiation generated blue-colored PDA state, as well as the heat treatment generated red-colored and fluorescent PDA state enables efficient visual imaging of a latent fingerprint, which is deposited on various colored solid surfaces.

A Nanoplatform with Precise Control over Release of Cargo for Enhanced Cancer Therapy

The development of a nanocarrier delivery system having both sufficient stability in blood circulation and a rapid drug release profile at target sites remains a major challenge in cancer therapy. Here, a multifunctional star-shaped micellar system with a precisely spatiotemporal control of releasing encapsulated agents is developed by mixing a photoinitiated crosslinking amphiphilic copolymer with a phenylboronic acid (PBA)-functionalized redox-sensitive amphiphilic copolymer for the first time. The combination of the functional polymers effectively resolves the contradiction that the micellar system cannot release the rapid drug release in cells when it possesses an extreme stability that is often required in blood circulation. In this system, the inner core polymers are photo-crosslinked, endowing a stable micelle matrix structure; the end groups of the hydrophilic segments are decorated with PBA ligands, providing an active targeting ability; disulfide bonds in the micellar matrix impart a redox-responsive trigger for the prompt intracellular release of drugs. As a result, with a relatively low DOX dosage (2 mg kg(-1) per injection) the in vivo antitumor effect on H22-bearing BALB/c mice shows that the micelles have a high therapeutic efficacy against solid tumors while minimal side effects against normal tissues.

Dual-Targeting Lactoferrin-Conjugated Polymerized Magnetic Polydiacetylene-Assembled Nanocarriers with Self-Responsive Fluorescence/Magnetic Resonance Imaging for In Vivo Brain Tumor Therapy

Maintaining a high concentration of therapeutic agents in the brain is difficult due to the restrictions of the blood-brain barrier (BBB) and rapid removal from blood circulation. To enable controlled drug release and enhance the blood-brain barrier (BBB)-crossing efficiency for brain tumor therapy, a new dual-targeting magnetic polydiacetylene nanocarriers (PDNCs) delivery system modified with lactoferrin (Lf) is developed. The PDNCs are synthesized using the ultraviolet (UV) cross-linkable 10,12-pentacosadiynoic acid (PCDA) monomers through spontaneous assembling onto the surface of superparamagnetic iron oxide (SPIO) nanoparticles to form micelles-polymerized structures. The results demonstrate that PDNCs will reduce the drug leakage and further control the drug release, and display self-responsive fluorescence upon intracellular uptake for cell trafficking and imaging-guided tumor treatment. The magnetic Lf-modified PDNCs with magnetic resonance imaging (MRI) and dual-targeting ability can enhance the transportation of the PDNCs across the BBB for tracking and targeting gliomas. An enhanced therapeutic efficiency can be obtained using Lf-Cur (Curcumin)-PDNCs by improving the retention time of the encapsulated Cur and producing fourfold higher Cur amounts in the brain compared to free Cur. Animal studies also confirm that Lf targeting and controlled release act synergistically to significantly suppress tumors in orthotopic brain-bearing rats.

Carbon nanotube-mediated delivery of budesonide to macrophages

A carbon nanotube-based carrier was developed for the delivery of anti-inflammatory budesonide to intracellular compartments of macrophages.

Photopolymerized micelles of diacetylene amphiphile: physical characterization and cell delivery properties

A series of polydiacetylene (PDA) - based micelles were prepared from diacetylenic surfactant bearing polyethylene glycol, by increasing UV-irradiation times. These polymeric lipid micelles were analyzed by physicochemical methods, electron microscopy and NMR analysis. Cellular delivery of fluorescent dye suggests that adjusting the polymerization state is vital to reach the full in vitro potential of PDA-based delivery systems.

Conducting polymer nanostructures for photocatalysis under visible light

Visible-light-responsive photocatalysts can directly harvest energy from solar light, offering a desirable way to solve energy and environment issues. Here, we show that one-dimensional poly(diphenylbutadiyne) nanostructures synthesized by photopolymerization using a soft templating approach have high photocatalytic activity under visible light without the assistance of sacrificial reagents or precious metal co-catalysts. These polymer nanostructures are very stable even after repeated cycling. Transmission electron microscopy and nanoscale infrared characterizations reveal that the morphology and structure of the polymer nanostructures remain unchanged after many photocatalytic cycles. These stable and cheap polymer nanofibres are easy to process and can be reused without appreciable loss of activity. Our findings may help the development of semiconducting-based polymers for applications in self-cleaning surfaces, hydrogen generation and photovoltaics.

Stable and compact zwitterionic polydiacetylene micelles with tumor-targeting properties

Stealth zwitterionic polydiacetylene-micelles are evaluated in vivo for the passive targeting of tumors.

Conducting polymer nanofibers with controlled diameters synthesized in hexagonal mesophases

Conducting poly(diphenylbutadiyne) (PDPB) nanofibers with controlled diameters (5 to 25 nm) and relatively high conductivity were synthesized in soft templates using UV and gamma irradiation.

Comparative assessment of the in vitro toxicity of some functionalized carbon nanotubes and fullerenes

Carbon nanotubes and fullerenes with different surface coatings are evaluated for their potential cytotoxicity on a panel of cell lines.

Magainin II modified polydiacetylene micelles for cancer therapy

Polydiacetylene (PDA) micelles have been widely used to deliver anticancer drugs in the treatment of a variety of tumours and for imaging living cells. In this study, we developed an effective strategy to directly conjugate magainin II (MGN-II) to the surface of PDA micelles using a fluorescent dye. These stable and well-defined PDA micelles had high cytotoxicity in cancer cell lines, and were able to reduce the tumour size in mice. The modified PDA micelles improved the anticancer effects of MGN-II in the A549 cell line only at a concentration of 16.0 μg mL(-1) (IC50). In addition, following irradiation with UV light at 254 nm, the PDA micelles gave rise to an energy transfer from the fluorescent dye to the backbone of PDA micelles to enhance the imaging of living cells. Our results demonstrate that modified PDA micelles can not only be used in the treatment of tumors in vitro and in vivo in a simple and directed way, but also offer a new platform for designing functional liposomes to act as anticancer agents.

Poly(methyl methacrylate)-supported polydiacetylene films: unique chromatic transitions and molecular sensing

Polydiacetylenes (PDAs) constitute a family of conjugated polymers exhibiting unique colorimetric and fluorescence transitions, and have attracted significant interest as chemo- and biosensing materials. We spin-coated PDA films upon poly(methyl methacrylate) (PMMA), and investigated the photophysical properties and sensing applications of the new PDA configuration. Specifically, the as-polymerized blue PDA layer underwent distinct transformations to purple, red, and yellow phases, which could be quantified through conventional color scanning combined with application of image analysis algorithms. Furthermore, we recorded a reversible red-purple PDA transition that was induced by ultraviolet irradiation, a phenomenon that had not been reported previously in PDA film systems. We show that distinct color and fluorescence transitions were induced in the PMMA-supported PDA films by amphiphilic substances-surfactants and ionic liquids-and that the chromatic transformations were correlated to the analyte structures and properties. Overall, this study presents a new chromatic PDA film system in which noncovalent interactions between the PMMA substrate and spin-coated PDA give rise to distinct chromatic properties and molecular sensing capabilities.

Positron emission tomography image-guided drug delivery: current status and future perspectives

Positron emission tomography (PET) is an important modality in the field of molecular imaging, which is gradually impacting patient care by providing safe, fast, and reliable techniques that help to alter the course of patient care by revealing invasive, de facto procedures to be unnecessary or rendering them obsolete. Also, PET provides a key connection between the molecular mechanisms involved in the pathophysiology of disease and the according targeted therapies. Recently, PET imaging is also gaining ground in the field of drug delivery. Current drug delivery research is focused on developing novel drug delivery systems with emphasis on precise targeting, accurate dose delivery, and minimal toxicity in order to achieve maximum therapeutic efficacy. At the intersection between PET imaging and controlled drug delivery, interest has grown in combining both these paradigms into clinically effective formulations. PET image-guided drug delivery has great potential to revolutionize patient care by in vivo assessment of drug biodistribution and accumulation at the target site and real-time monitoring of the therapeutic outcome. The expected end point of this approach is to provide fundamental support for the optimization of innovative diagnostic and therapeutic strategies that could contribute to emerging concepts in the field of “personalized medicine”. This review focuses on the recent developments in PET image-guided drug delivery and discusses intriguing opportunities for future development. The preclinical data reported to date are quite promising, and it is evident that such strategies in cancer management hold promise for clinically translatable advances that can positively impact the overall diagnostic and therapeutic processes and result in enhanced quality of life for cancer patients.

Fusion of [(18)F]FDG PET with fluorescence diffuse optical tomography to improve validation of probes and tumor imaging

Purpose

Given the progress of fluorescence diffuse optical tomography (fDOT) technology, here, we study the additional benefits provided by multimodal PET/fDOT imaging by comparing the biodistribution of 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) in tumors with three fluorescent probes: a glucose analog, a protease activatable optical probe, and a ligand of αvβ3 integrin.

Procedures

Sequential fDOT/PET/computed tomography (CT) imaging of mice was performed with a custom multimodal mouse support that allows the subject to be transferred between the fDOT and the PET/CT scanners. Experiments were performed in xenografted tumor models derived from the human breast cancer line MDA-MB 231 and compared to ex vivo analysis.

Results

The three-dimensional signals showed that the fluorescent glucose analog is not colocalized with [¹⁸F]FDG, raising questions about its use as a surrogate probe of the PET tracer. Fusion of [¹⁸F]FDG with the other fluorescent probes showed evidence of high variability both for the protease activity and the αvβ3 integrin expression during tumor growth.

Conclusion

The added value of hybrid PET/fDOT over the two modalities was demonstrated for cross-validation of probes and for better characterization of tumor models.

Multifunctional polydiacetylene-liposome with controlled release and fluorescence tracing

A multifunctional polydiacetylene-liposome (PDA-liposome) was prepared by self-assembly, which can be characterized with controlled drug release and fluorescence tracing.

Synthesis, gelation and topochemical polymerization of meta-linked oligophenylenebutadiynylene derivatives

Rational design ofmeta-linked oligophenylbutadiynylene (OPBD) derivatives was conducted in order to gain insight into their gelation properties and reactivity toward topochemical polymerization to yield polydiacetylenes (PDAs).

Cellular uptake and trafficking of polydiacetylene micelles

Polydiacetylene (PDA) micelles coated with either carboxylate-, ammonium-, or methoxy-polyethyleneglycol (PEG) chains were assembled and loaded with a fluorescent dye (DiO). Their interaction with MCF-7 human breast tumor cells was investigated by epi-fluorescence microscopy and fluorescence-activated cell sorting (FACS) to determine their internalization pathway and intracellular fate. It was found that the ionic character of the micelles influenced their internalization kinetics through a caveolae-mediated pathway and that all micelle types behaved somewhat similarly inside cells.