Cell viability imaging in tumor spheroids DNA binding of a ruthenium(II) light-switch complex.

The famous ''light-switch'' ruthenium complex [Ru(bpy)(dppz)](PF) (1) has been long known for its DNA binding properties . However, the biological utility of this compound has been hampered by its poor cellular uptake in living cells. Here we report a bioimaging application of 1 as cell viability probe in both 2D cells monolayer and 3D multi-cellular tumor spheroids of various human cancer cell lines (U87, HepG2, A549).

Photosubstitution in a trisheteroleptic ruthenium complex inhibits conjunctival melanoma growth in a zebrafish orthotopic xenograft model.

data are rare but essential for establishing the clinical potential of ruthenium-based photoactivated chemotherapy (PACT) compounds, a new family of phototherapeutic drugs that are activated ligand photosubstitution. Here a novel trisheteroleptic ruthenium complex [Ru(dpp)(bpy)(mtmp)](PF) ([2](PF), dpp = 4,7-diphenyl-1,10-phenanthroline, bpy = 2,2'-bipyridine, mtmp = 2-methylthiomethylpyridine) was synthesized and its light-activated anticancer properties were validated in cancer cell monolayers, 3D tumor spheroids, and in embryonic zebrafish cancer models. Upon green light irradiation, the non-toxic mtmp ligand is selectively cleaved off, thereby releasing a phototoxic ruthenium-based photoproduct capable notably of binding to nuclear DNA and triggering DNA damage and apoptosis within 24-48 h.

Flavin-Conjugated Nanobombs: Key Structural Requirements Governing Their Self-Assemblies' Morphologies.

In contrast to artificial molecules, natural photosensitizers have the benefit of excellent toxicity profiles and of life-compatible activating energy ranges. Flavins are such photosensitizers that were selected by nature in a plethora of light-triggered biochemical reactions. Flavin-rich nanoparticles could thus emerge as promising tools in photodynamic therapies and in active-targeting drug delivery.

Mimicking Photosystem I with a Transmembrane Light Harvester and Energy Transfer-Induced Photoreduction in Phospholipid Bilayers.

Invited for the cover of this issue are Andrea Pannwitz, Sylvestre Bonnet and co-workers at Leiden University and Johns Hopkins University. The image depicts an observer watching over a lipid bilayer "landscape" and a sky full of luminescent giant vesicles. Read the full text of the article at 10.

Biotin-decorated all-HPMA polymeric micelles for paclitaxel delivery.

To avoid poly(ethylene glycol)-related issues of nanomedicines such as accelerated blood clearance, fully N-2-hydroxypropyl methacrylamide (HPMAm)-based polymeric micelles decorated with biotin for drug delivery were designed. To this end, a biotin-functionalized chain transfer agent (CTA), 4-cyano-4-[(dodecylsulfanylthiocarbonyl)-sulfanyl]pentanoic acid (biotin-CDTPA), was synthesized for reversible addition-fragmentation chain-transfer (RAFT) polymerization. Amphiphilic poly(N-2-hydroxypropyl methacrylamide)-block-poly(N-2-benzoyloxypropyl methacrylamide) (p(HPMAm)-b-p(HPMAm-Bz)) with molecular weights ranging from 8 to 24 kDa were synthesized using CDTPA or biotin-CDTPA as CTA and 2,2'-azobis(2-methylpropionitrile) as initiator.

Mimicking Photosystem I with a Transmembrane Light Harvester and Energy Transfer-Induced Photoreduction in Phospholipid Bilayers.

Photosystem I (PS I) is a transmembrane protein that assembles perpendicular to the membrane, and performs light harvesting, energy transfer, and electron transfer to a final, water-soluble electron acceptor. We present here a supramolecular model of it formed by a bicationic oligofluorene 1 bound to the bisanionic photoredox catalyst eosin Y (EY ) in phospholipid bilayers. According to confocal microscopy, molecular modeling, and time dependent density functional theory calculations, 1 prefers to align perpendicularly to the lipid bilayer.

Systematic evaluation of design features enables efficient selection of Π electron-stabilized polymeric micelles.

Polymeric micelles (PM) based on poly(ethylene glycol)-b-poly(N-2-benzoyloxypropyl methacrylamide) (mPEG-b-p(HPMA-Bz)) loaded with paclitaxel (PTX-PM) have shown promising results in overcoming the suboptimal efficacy/toxicity profile of paclitaxel. To get insight into the stability of PTX-PM formulations upon storage and to optimize their in vivo tumor-targeted drug delivery properties, we set out to identify a lead PTX-PM formulation with the optimal polymer composition. To this end, PM based on four different mPEG-b-p(HPMA-Bz) block copolymers with varying molecular weight of the hydrophobic block (17-3 kDa) were loaded with different amounts of PTX.

Photo-Uncaging of a Microtubule-Targeted Rigidin Analogue in Hypoxic Cancer Cells and in a Xenograft Mouse Model.

Marine alkaloid rigidins are cytotoxic compounds known to kill cancer cells at nanomolar concentrations by targeting the microtubule network. Here, a rigidin analogue containing a thioether group was "caged" by coordination of its thioether group to a photosensitive ruthenium complex. In the dark, the coordinated ruthenium fragment prevented the rigidin analogue from inhibiting tubulin polymerization and reduced its toxicity in 2D cancer cell line monolayers, 3D lung cancer tumor spheroids (A549), and a lung cancer tumor xenograft (A549) in nude mice.

Liposome-targeted recombinant human acid sphingomyelinase: Production, formulation, and in vitro evaluation.

Niemann-Pick disease type B is a hereditary rare condition caused by deficiency of the acid sphingomyelinase (ASM) that is needed for lysosomal hydrolysis of sphingomyelin to ceramide and phosphocholine. This deficiency leads to a massive accumulation of sphingomyelin in cells throughout the body, predominantly in the liver, spleen and lungs. Currently, there is no effective treatment available.

Selective Cytotoxicity to HER2 Positive Breast Cancer Cells by Saporin-Loaded Nanobody-Targeted Polymeric Nanoparticles in Combination with Photochemical Internalization.

In cancer treatment, polymeric nanoparticles (NPs) can serve as a vehicle for the delivery of cytotoxic proteins that have intracellular targets but that lack well-defined mechanisms for cellular internalization, such as saporin. In this work, we have prepared PEGylated poly(lactic acid- co-glycolic acid- co-hydroxymethyl glycolic acid) (PLGHMGA) NPs for the selective delivery of saporin in the cytosol of HER2 positive cancer cells. This selective uptake was achieved by decorating the surface of the NPs with the 11A4 nanobody that is specific for the HER2 receptor.

Thermosensitive liposomes for triggered release of cytotoxic proteins.

Lysolipid-containing thermosensitive liposomes (LTSL) are clinically-relevant drug nanocarriers which have been used to deliver small molecule cytostatics to tumors in combination with local hyperthermia (42 °C) to trigger local drug release. The objective of this study was to investigate the feasibility of LTSL for encapsulation and triggered release of macromolecular drugs such as plant-derived cytotoxins. As therapeutic protein we used Mistletoe lectin-1 (ML1) - a ribosome-inactivating protein with potent cytotoxic activity in tumor cells.

Influence of PEGylation of Vitamin-K-Loaded Mixed Micelles on the Uptake by and Transport through Caco-2 Cells.

The aim of the study is to investigate the uptake by and transport through Caco-2 cells of two mixed micelle formulations (based on egg phosphatidylcholine and glycocholic acid) of vitamin K, i.e., with and without DSPE-PEG2000.

Luminescent Gold Nanocluster-Decorated Polymeric Hybrid Particles with Assembly-Induced Emission.

Ultrasmall gold atom clusters (<2 nm in diameter) or gold nanoclusters exhibit emergent photonic properties (near-infrared absorption and emission) compared to larger plasmonic gold particles because of the significant quantization of their conduction band. Although single gold nanocluster properties and applications are being increasingly investigated, little is still known about their behavior and properties when assembled into suprastructures, and even fewer studies are investigating their use for biomedical applications. Here, a simple synthetic pathway combines gold nanoclusters with thermosensitive diblock copolymers of poly(ethylene glycol) (PEG) and poly( N-isopropylacrylamide) (PNIPAm) to form a new class of gold-polymer, micelle-forming, hybrid nanoparticle.

Quantitative analysis of receptor-mediated uptake and pro-apoptotic activity of mistletoe lectin-1 by high content imaging.

Ribosome inactivating proteins (RIPs) are highly potent cytotoxins that have potential as anticancer therapeutics. Mistletoe lectin 1 (ML1) is a heterodimeric cytotoxic protein isolated from European Mistletoe and belongs to RIP class II. The aim of this project was to systematically study ML1 cell binding, endocytosis pathway(s), subcellular processing and apoptosis activation.

Balancing Passive and Active Targeting to Different Tumor Compartments Using Riboflavin-Functionalized Polymeric Nanocarriers.

Riboflavin transporters (RFTs) and the riboflavin carrier protein (RCP) are highly upregulated in many tumor cells, tumor stem cells, and tumor neovasculature, which makes them attractive targets for nanomedicines. Addressing cells in different tumor compartments requires drug carriers, which are not only able to accumulate via the EPR effect but also to extravasate, target specific cell populations, and get internalized by cells. Reasoning that antibodies are among the most efficient targeting systems developed by nature, we consider their size (∼10-15 nm) to be ideal for balancing passive and active tumor targeting.

Overcoming multidrug resistance using folate receptor-targeted and pH-responsive polymeric nanogels containing covalently entrapped doxorubicin.

Multidrug resistance (MDR) contributes to failure of chemotherapy. We here show that biodegradable polymeric nanogels are able to overcome MDR via folic acid targeting. The nanogels are based on hydroxyethyl methacrylamide-oligoglycolates-derivatized poly(hydroxyethyl methacrylamide-co-N-(2-azidoethyl)methacrylamide) (p(HEMAm-co-AzEMAm)-Gly-HEMAm), covalently loaded with the chemotherapeutic drug doxorubicin (DOX) and subsequently decorated with a folic acid-PEG conjugate via copper-free click chemistry.

Photoacoustic imaging of tumor targeting with riboflavin-functionalized theranostic nanocarriers.

Photoacoustic imaging is an emerging method in the molecular imaging field, providing high spatiotemporal resolution and sufficient imaging depths for many clinical applications. Therefore, the aim of this study was to use photoacoustic imaging as a tool to evaluate a riboflavin (RF)-based targeted nanoplatform. RF is internalized by the cells through a specific pathway, and its derivatives were recently shown as promising tumor-targeting vectors for the drug delivery systems.

Noninvasive Assessment of Elimination and Retention using CT-FMT and Kinetic Whole-body Modeling.

Fluorescence-mediated tomography (FMT) is a quantitative three-dimensional imaging technique for preclinical research applications. The combination with micro-computed tomography (µCT) enables improved reconstruction and analysis. The aim of this study is to assess the potential of µCT-FMT and kinetic modeling to determine elimination and retention of typical model drugs and drug delivery systems.

Small nanosized poly(vinyl benzyl trimethylammonium chloride) based polyplexes for siRNA delivery.

The success of siRNA gene therapy requires the availability of safe and efficient delivery systems. In the present study, we investigated poly(vinyl benzyl trimethylammonium chloride) (PVTC) and its block copolymer with poly(oligo(ethyleneglycol) methacrylate) (POEGMA) as delivery vector for siRNA. Small polyplexes ranging from 8 to 25nm in diameter were formed in aqueous solution by spontaneous self-assembly of both the homopolymer and block copolymer with siRNA and the formed particles were stable at physiological ionic strength.

Iron nanomedicines induce Toll-like receptor activation, cytokine production and complement activation.

Approximately a dozen of intravenous iron nanomedicines gained marketing authorization in the last two decades. These products are generally considered as safe, but have been associated with an increased risk for hypersensitivity-like reactions of which the underlying mechanisms are unknown. We hypothesized that iron nanomedicines can trigger the innate immune system.

Amphiphilic Phospholipid-Based Riboflavin Derivatives for Tumor Targeting Nanomedicines.

Riboflavin (RF) is an essential vitamin for cellular metabolism. Recent studies have shown that RF is internalized through RF transporters, which are highly overexpressed by prostate and breast cancer cells, as well as by angiogenic endothelium. Here, we present an optimized synthesis protocol for preparing tailor-made amphiphilic phospholipid-based RF derivatives using phosphoramidite chemistry.

Bioengineered riboflavin in nanotechnology.

Riboflavin (RF) is an essential water-soluble vitamin with unique biological and physicochemical properties such as transporterspecific cell internalization, implication in redox reactions, fluorescence and photosensitizing. Due to these features RF attracted researchers in various fields from targeted drug delivery and tissue engineering to optoelectronics and biosensors. In this review we will give a brief reminder of RF chemistry, its optical, photosensitizing properties, RF transporter systems and its role in pathologies.

Refinement of adsorptive coatings for fluorescent riboflavin-receptor-targeted iron oxide nanoparticles.

Flavin mononucleotide (FMN) is a riboflavin derivative that can be exploited to target the riboflavin transporters (RFTs) and the riboflavin carrier protein (RCP) in cells with high metabolic activity. In this study we present the synthesis of different FMN-coated ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) and their efficiency as targeting contrast agents. Since FMN alone cannot stabilize the nanoparticles, we used adenosine phosphates--AMP, ADP and ATP--as spacers to obtain colloidally stable nanoparticles.

Quantum dot lipid oligonucleotide bioconjugates: toward a new anti-microRNA nanoplatform.

The construction of new nanotools is presented here using the example of fluorescent semiconductor nanocrystals, quantum dots (QDs). In this study, the implementation of the new lipid oligonucleotide conjugate-functionalized quantum dots (LON-QDs) is realized in four steps: (i) the synthesis of the lipid oligonucleotide conjugates (LONs), (ii) the encapsulation of QDs by nucleolipids and LONs, (iii) the study of the duplex formation of LON-QDs with the complementary ON partners, and (iv) the cellular uptake of the LON-QD platform and hybridization with the target ONs (microRNA and miR-21).