Novel Antifouling Coatings by Zwitterionic Silica Grafting on Glass Substrates.

Zwitterionic silica coatings for surface functionalization are greatly prominent because of their simple and fast preparation, high availability, and effective antifouling properties. In this work, two zwitterionic sulfobetaine silane coatings, i.e., mono-SBSi and tris-SBSi, were deposited on glass surfaces and tested for antifouling of biological material and biofilm using human cancer cell and seawater, respectively. The used zwitterionic precursors mono-SBSi and tris-SBSi differ by the number of hydrolyzable silane groups: mono-SBSi contains one trimethoxysilane group, whereas tris-SBSi contains three of these functions. First, X-ray photoelectron spectroscopy indicates the successful grafting of zwitterionic coatings onto a glass surface. Characterization using atomic force microscopy shows the different morphologies and roughness of the two coatings. The glass surface became more hydrophilic after the grafting of zwitterionic coatings than the bare glass substrate. The antifouling properties of two coatings were evaluated via human cancer cell adsorption. Interestingly, the tris-SBSi coating displays a significantly lower level of cell adsorption compared to that of both mono-SBSi coating and the non-modified control surface. The same trend was observed for biofilm formation in seawater. Finally, the toxicity of mono-SBSi and tris-SBSi coatings was evaluated on zebrafish embryos, indicating the good biocompatibility of both coatings. Our results indicate interesting antifouling properties of zwitterionic coatings. The chemical constitution of the used precursor has an impact on the antifouling properties of the formed coating: the tris-SBSi-based zwitterionic silica coatings display improved antifouling properties compared to those of the mono-SBSi-based coating. Besides, the use of trisilylated precursors should result in the formation of more resistant and robust coatings due to the higher number of grafting functions. For all these reasons, we anticipate that tris-SBSi coatings will open new perspectives for antifouling applications for biological environments and implants.

Nanoencapsulation of a Far-Red Absorbing Phthalocyanine into Poly(benzylmalate) Biopolymers and Modulation of Their Photodynamic Efficiency.

Two different poly(benzylmalate) biopolymers, a hydrophobic non-PEGylated (PMLABe73) and an amphiphilic PEGylated derivative (PEG42-b-PMLABe73), have been used to encapsulate a phthalocyanine chosen for its substitution pattern that is highly suitable for photodynamic therapy. Different phthalocyanine/(co)polymers ratios have been used for the nanoprecipitation. A set of six nanoparticles has been obtained. If the amphiphilic PEGylated copolymer proved to be slightly more efficient for the encapsulation and to lower the aggregation of the phthalocyanine inside the nanoparticles, it is, however, the hydrophobic PMLABe73-based nanoparticles that exhibited the best photodynamic efficiency.

Imidazo[1,2-a]pyridine and Imidazo[1,5-a]pyridine: Electron Donor Groups in the Design of D-π-A Dyes.

This work investigates the electron-donating capabilities of two 10-π electron nitrogen bridgehead bicyclic [5,6]-fused ring systems, imidazo[1,2-a]pyridine and imidazo[1,5-a]pyridine rings. Eight compounds with varying positions of electron-withdrawing moieties (TCF or DCI) coupled to the imidazopyridine ring were synthesized and studied. DCI-containing compounds (Ib-IVb) exhibited a purely dipolar nature with broad absorption bands, weak fluorescence, large Stokes shifts, and strong solvatochromism. In contrast, TCF-containing compounds (Ia-IVa) demonstrated diverse properties. Imidazo[1,2-a]pyridine derivatives Ia and IIa were purely dipolar, while imidazo[1,5-a]pyridine derivatives IIIa and IVa displayed a cyanine-like character with intense absorption and higher quantum yields of emission. The observed gradual red shift in optical properties with changing electron-donor groups (IIb < Ib < IIIb < IVb) and (IIa < Ia < IIIa < IVa) underscores the stronger electron-donor character of imidazo[1,5-a]pyridine compared to that of imidazo[1,2-a]pyridine. Furthermore, crystalline powders of imidazo[1,2-a]pyridine derivatives exhibited fluorescence despite minimal emission in solution. Two compounds (Ib and IVa) were successfully formulated into nanoparticles for potential in vivo imaging applications in zebrafish embryos.

Self-assembled porphyrin-peptide cages for photodynamic therapy.

The development of photodynamic therapy requires access to smart photosensitizers which combine appropriate photophysical and biological properties. Interestingly, supramolecular and dynamic covalent chemistries have recently shown their ability to produce novel architectures and responsive systems through simple self-assembly approaches. Herein, we report the straightforward formation of porphyrin-peptide conjugates and cage compounds which feature on their surface chemical groups promoting cell uptake and specific organelle targeting. We show that they self-assemble, in aqueous media, into positively-charged nanoparticles which generate singlet oxygen upon green light irradiation, while also undergoing a chemically-controlled disassembly due to the presence of reversible covalent linkages. Finally, the biological evaluation in cells revealed that they act as effective photosensitizers and promote synergistic effects in combination with Doxorubicin.

A Triazolium-Anchored Self-Immolative Linker Enables Self-Assembly-Driven siRNA Binding and Esterase-Induced Release.

The increased importance of RNA-based therapeutics comes with a need to develop next-generation stimuli-responsive systems capable of binding, transporting and releasing RNA oligomers. In this work, we describe triazolium-based amphiphiles capable of siRNA binding and enzyme-responsive release of the nucleic acid payload. In aqueous medium, the amphiphile self-assembles into nanocarriers that can disintegrate upon the addition of esterase. Key to the molecular design is a self-immolative linker that is anchored to the triazolium moiety and acts as a positively-charged polar head group. We demonstrate that addition of esterase leads to a degradation cascade of the linker, leaving the neutral triazole compound unable to form complexes and therefore releasing the negatively-charged siRNA. The reported molecular design and overall approach may have broad utility beyond this proof-of-principle study, because the underlying CuAAC "click" chemistry allows bringing together three groups very efficiently as well as cleaving off one of the three groups under the mild action of an esterase enzyme.

Structure-Activity Relationships in Nucleic-Acid-Templated Vectors Based on Peptidic Dynamic Covalent Polymers.

The use of nucleic acids as templates, which can trigger the self-assembly of their own vectors represent an emerging, simple and versatile, approach toward the self-fabrication of tailored nucleic acids delivery vectors. However, the structure-activity relationships governing this complex templated self-assembly process that accompanies the complexation of nucleic acids remains poorly understood. Herein, the class of arginine-rich dynamic covalent polymers (DCPs) composed of different monomers varying the number and position of arginines were studied. The combinations that lead to nucleic acid complexation, in saline buffer, using different templates, from short siRNA to long DNA, are described. Finally, a successful peptidic DCP featuring six-arginine repeating unit that promote the safe and effective delivery of siRNA in live cancer cells was identified.

Superparamagnetic Spinel-Ferrite Nano-Adsorbents Adapted for Hg2+, Dy3+, Tb3+ Removal/Recycling: Synthesis, Characterization, and Assessment of Toxicity.

In the present work, superparamagnetic adsorbents based on 3-aminopropyltrimethoxy silane (APTMS)-coated maghemite (γFe2O3@SiO2-NH2) and cobalt ferrite (CoFe2O4@SiO2-NH2) nanoparticles were prepared and characterized using transmission-electron microscopy (TEM/HRTEM/EDXS), Fourier-transform infrared spectroscopy (FTIR), specific surface-area measurements (BET), zeta potential (ζ) measurements, thermogravimetric analysis (TGA), and magnetometry (VSM). The adsorption of Dy3+, Tb3+, and Hg2+ ions onto adsorbent surfaces in model salt solutions was tested. The adsorption was evaluated in terms of adsorption efficiency (%), adsorption capacity (mg/g), and desorption efficiency (%) based on the results of inductively coupled plasma optical emission spectrometry (ICP-OES). Both adsorbents, γFe2O3@SiO2-NH2 and CoFe2O4@SiO2-NH2, showed high adsorption efficiency toward Dy3+, Tb3+, and Hg2+ ions, ranging from 83% to 98%, while the adsorption capacity reached the following values of Dy3+, Tb3+, and Hg2+, in descending order: Tb (4.7 mg/g) > Dy (4.0 mg/g) > Hg (2.1 mg/g) for γFe2O3@SiO2-NH2; and Tb (6.2 mg/g) > Dy (4.7 mg/g) > Hg (1.2 mg/g) for CoFe2O4@SiO2-NH2. The results of the desorption with 100% of the desorbed Dy3+, Tb3+, and Hg2+ ions in an acidic medium indicated the reusability of both adsorbents. A cytotoxicity assessment of the adsorbents on human-skeletal-muscle derived cells (SKMDCs), human fibroblasts, murine macrophage cells (RAW264.7), and human-umbilical-vein endothelial cells (HUVECs) was conducted. The survival, mortality, and hatching percentages of zebrafish embryos were monitored. All the nanoparticles showed no toxicity in the zebrafish embryos until 96 hpf, even at a high concentration of 500 mg/L.

Assembly of Aggregation-Induced Emission Active Bola-Amphiphilic Macromolecules into Luminescent Nanoparticles Optimized for Two-Photon Microscopy In Vivo.

The (Z) and (E)-isomers of an extended tetraphenylethylene-based chromophore with optimized two-photon-induced luminescence properties are separated and functionalized with water-solubilizing pendant polymer groups, promoting their self-assembly in physiological media in the form of small, colloidal stable organic nanoparticles. The two resulting fluorescent suspensions are then evaluated as potential two-photon luminescent contrast agents for intravital epifluorescence and two-photon fluorescence microscopy. Comparisons with previously reported works involving similar fluorophores devoid of polymer side chains illustrate the benefits of later functionalization regarding the control of the self-assembly of the nano-objects and ultimately their biocompatibility toward the imaged organism.

D-Mannose-appended 5,15-diazaporphyrin for photodynamic therapy.

5,15-Diazaporphyrin appended with D-mannose moieties was prepared through Suzuki-Miyaura cross-coupling reaction and SN2 alkylation. The resultant diazaporphyrin was hydrophilic enough to exhibit sufficient solubility in aqueous media. Because of the photosensitizing ability of diazaporphyrins, the in vitro activity of the D-mannose-appended diazaporphyrin in photodynamic therapy (PDT) was investigated. The specific internalization of the functionalized diazaporphyrin into human breast adenocarcinoma (MDA-MB-231) cells through mannose receptors was confirmed by confocal microscopy imaging. We also demonstrated the strong PDT activity of the functionalized diazaporphyrin at a nanomolar level with short light irradiation time.

Cell-Selective siRNA Delivery Using Glycosylated Dynamic Covalent Polymers Self-Assembled In†Situ by RNA Templating.

Dynamic covalent libraries enable exploring complex chemical systems from which bioactive assemblies can adaptively emerge through template effects. In this work, we studied dynamic covalent libraries made of complementary bifunctional cationic peptides, yielding a diversity of species from macrocycles to polymers. Although polymers are typically expressed only at high concentration, we found that siRNA acts as a template in the formation of dynamic covalent polymers at low concentration in a process guided by electrostatic binding. Using a glycosylated building block, we were able to show that this templated polymerization further translates into the multivalent presentation of carbohydrate ligands, which subsequently promotes cell uptake and even cell-selective siRNA delivery.

Imidazopyridine-fused [1,3]diazepinones: modulations of positions 2 to 4 and their impacts on the anti-melanoma activity.

A series of 19 novel pyrido-imidazodiazepinones, with modulations of positions 2, 3 and 4 of the diazepine ring were synthesised and screened for their in vitro cytotoxic activities against two melanoma cell lines (A375 and MDA-MB-435) and for their potential toxicity against NIH-3T3 non-cancerous cells. Selected compounds were also evaluated on the NCI-60 cell line panel. The SAR study revealed that the molecular volume and the cLogP of compounds modified at position 2 were significantly correlated with the activity of these compounds on melanoma cell lines. Moreover, introduction of a heterocyclic group at position 2 or an azido-alkyl chain at position 4 led to compounds displaying a significantly different activity profile on the NCI-60 cell line panel, compared to phenyl-substituted compounds at position 2 of the diazepinone. This study provides us crucial information for the development of new derivatives active against melanoma.

Topological Requirements for CI-M6PR-Mediated Cell Uptake.

The 300 kDa cation-independent M6P receptor (CI-MPR) mediates ligand internalization and trafficking to the endolysosomal compartments. Because of its endocytotic nature, it has been recognized as a promising class of receptors for target component delivery. Its cellular uptake involves the simultaneous binding of two protein units resulting in the formation of receptor dimers. While many multivalent glycoconjugates have been reported to date, little is known about the topological requests to induce an effective recruitment of CI-MPRs. We herein describe the synthesis and cell uptake ability of a set of highly organized glycoclusters bearing one to three saccharide units. The spatial arrangement of carbohydrate ligands is ensured by a heterocyclic γ-peptide central core.

Synthesis and Anticancer Activity of Gold Porphyrin Linked to Malonate Diamine Platinum Complexes.

Recently, gold(III) porphyrins have gained great interest as anticancer drugs not only for the stability of gold(III) but also for the functionalization of the porphyrin to allow bridging with another metal such as platinum(II). We report here, for the first time, the synthesis of three new bimetal compounds containing a gold(III) porphyrin conjugated to a platinum diamine moiety through malonate bridging to obtain enhanced cytotoxicity from both metals combined with the phototoxicity of the porphyrin. The three complexes differ in the type of diamine ligand around platinum(II): ammonia (NH3), cyclohexanediamine (CyDA), and pyridylmethylamine (Py). The synthesis was carried out using the complexation of activated malonic acid derivatives with aquadiaminoplatinum(II) complexes, and the products were characterized by IR, NMR, mass spectra, and elementary analysis. The cytotoxic activity of the conjugates was screened in both healthy cell lines and cancer cell lines, human fibroblast cells (FS-68) and human breast cancer cells (MCF-7), and was compared to that of the corresponding platinum(II) complexes. The cyclohexyldiamine (CyDA) derivative exhibited the greatest cytotoxic effect among the series. The results showed that Au(III)/Pt(II) conjugates are more potent by 2-5.6-fold than the corresponding platinum complexes. Moreover, the dyad AuP-PtCyDA is 18% more potent and also more selective toward cancer cells than the parent gold porphyrin substituted with malonic acid. On the other hand, the IC50 of the dyad AuP-PtCyDA is 43% lower than that of AuTPP but is more selective toward healthy cells. Singlet oxygen measurements indicated that gold(III) porphyrin derivatives are poor oxygen sensitizers and cell death occurred potentially due to generation of other reactive oxygen species (ROS) upon reductive quenching of the gold porphyrin excited state. In addition, the increase in cancer cell death obtained after light irradiation is totally absent in healthy cells, demonstrating the specificity of this PDT treatment on cancer cells. Our findings imply that the incorporation of two different cytotoxic metals in the same molecule represents a remarkable cytotoxic effect in comparison to traditional homometallic Pt(II) drugs.

Can Heterocyclic γ-Peptides Provide Polyfunctional Platforms for Synthetic Glycocluster Construction?

Sugars play key roles in many molecular and cellular communication processes involving a family of proteins named lectins. The low affinity associated with sugar recognition is generally counterbalanced by the multivalent nature of the interaction. While many polyglycosylated architectures have been described, only a few studies focused on the impact of topology variations of the multivalent structures on the interaction with lectin proteins. One major interest of our group concerns the design of new highly predictable and stable molecular pseudo-peptide architectures for therapeutic applications. In such a context, we described a class of constrained heterocyclic γ-amino acids built around a thiazole ring, named ATCs. ATC oligomers are helical molecules resulting from the formation of a highly stable C9 hydrogen-bonding pattern. Following our program, we herein address the potential of ATC oligomers as tunable scaffolds for the development of original multivalent glycoclusters.

Exceptional anticancer photodynamic properties of [1,4-Bis(3,6,9,12-Tetraoxatridec-1-yloxy)phthalocyaninato]zinc(II).

Phthalocyanines have been described as effective photosensitizers for photodynamic therapy and are therefore, being studied for their biomedical applications. The metalation of photosensitizers can improve their photodynamic therapy potential. Here, we focus on the biological properties of [1,4-Bis(3,6,9,12-Tetraoxatridec-1-yloxy)phthalocyaninato]zinc(II) (ZnPc(αEG4)2) and demonstrate its exceptional anticancer activity upon light stimulation to kill preferentially cancer cells with a start of efficiency at 10 pM. Indeed, in this work we highlighted the high selectivity of ZnPc(αEG4)2 for cancer cells compared with healthy ones and we establish its mechanism of action, enabling us to conclude that ZnPc(αEG4)2 could be a powerful tool for cancer therapy.

Probing the Use of Triphenyl Phosphonium Cation for Mitochondrial Nucleoside Delivery.

Herein, we report the design, the synthesis, and the study of novel triphenyl phosphonium-based nucleoside conjugates. 2'-Deoxycytidine was chosen as nucleosidic cargo, as it allows the introduction of fluorescein on the exocyclic amine of the nucleobase and grafting of the vector was envisaged through the formation of a biolabile ester bond with the hydroxyl function at the 5'-position. Compound 3 was identified as a potential nucleoside prodrug, showing ability to be internalized efficiently into cells and to be co-localized with mitochondria.

Engineered therapeutic antibodies with mannose 6-phosphate analogues as a tool to degrade extracellular proteins.

Inducing the degradation of pathological soluble antigens could be the key to greatly enhancing the efficacy of therapeutic monoclonal antibodies (mAbs), extensively used in the treatment of autoimmune and inflammatory disorders or cancer. Lysosomal targeting has gained increasing interest in recent years due to its pharmaceutical applications far beyond the treatment of lysosomal diseases, as a way to address proteins to the lysosome for eventual degradation. Mannose 6-phosphonate derivatives (M6Pn), called AMFA, are unique glycovectors that can significantly enhance the cellular internalization of the proteins conjugated to AMFA via the cation-independent mannose 6-phosphate receptor (M6PR) pathway. AMFA engineering of mAbs results in the generation of a bifunctional antibody that is designed to bind both the antigen and the M6PR. The improvement of the therapeutic potential by AMFA engineering was investigated using two antibodies directed against soluble antigens: infliximab (IFX), directed against tumor necrosis factor α (TNF-α), and bevacizumab (BVZ), directed against the vascular endothelial growth factor (VEGF). AMFA conjugations to the antibodies were performed either on the oligosaccharidic chains of the antibodies or on the lysine residues. Both conjugations were controlled and reproducible and provided a novel affinity for the M6PR without altering the affinity for the antigen. The grafting of AMFA to mAb increased their cellular uptake through an M6PR-dependent mechanism. The antigens were also 2.6 to 5.7 times more internalized by mAb-AMFA and rapidly degraded in the cells. Additional cell culture studies also proved the significantly higher efficacy of IFX-AMFA and BVZ-AMFA compared to their unconjugated counterparts in inhibiting TNF-α and VEGF activities. Finally, studies in a zebrafish embryo model of angiogenesis and in xenografted chick embryos showed that BVZ-AMFA was more effective than BVZ in reducing angiogenesis. These results demonstrate that AMFA grafting induces the degradation of soluble antigens and a significant increase in the therapeutic efficacy. Engineering with mannose 6-phosphate analogues has the potential to develop a new class of antibodies for autoimmune and inflammatory diseases.

Super-resolution imaging of antibody-conjugated biodegradable periodic mesoporous organosilica nanoparticles for targeted chemotherapy of prostate cancer.

Biodegradable periodic mesoporous organosilica nanoparticles (nanoPMOs) are widely used as responsive drug delivery platforms for targeted chemotherapy of cancer. However, the evaluation of their properties such as surface functionality and biodegradability is still challenging, which has a significant impact on the efficiency of chemotherapy. In this study, we have applied direct stochastic optical reconstruction microscopy (dSTORM), a single-molecule super-resolution microscopy technique, to quantify the degradation of nanoPMOs triggered by glutathione and the multivalency of antibody-conjugated nanoPMOs. Subsequently, the effect of these properties on cancer cell targeting, drug loading and release capability, and anticancer activity is also studied. Due to the higher spatial resolution at the nanoscale, dSTORM imaging is able to reveal the structural properties (i.e., size and shape) of fluorescent and biodegradable nanoPMOs. The quantification of nanoPMOs' biodegradation using dSTORM imaging demonstrates their excellent structure-dependent degradation behavior at a higher glutathione concentration. The surface functionality of anti-M6PR antibody-conjugated nanoPMOs as quantified by dSTORM imaging plays a key role in prostate cancer cell labeling: oriented antibody is more effective than random ones, while high multivalency is also effective. The higher biodegradability and cancer cell-targeting properties of nanorods conjugated with oriented antibody (EAB4H) effectively deliver the anticancer drug doxorubicin to cancer cells, exhibiting potent anticancer effects.

Periodic Mesoporous Ionosilica Nanoparticles for BODIPY Delivery and Photochemical Internalization of siRNA.

Periodic Mesoporous Ionosilica Nanoparticles (PMINPs) made via co-condensation reactions starting from an ionosilica precursor and a porphyrin derivative were used for simultaneous BODIPY/siRNA delivery in cancer cells. We observed high BODIPY loading capacities and efficiencies of the PMINPs that are triggered by anion exchange. siRNA adsorption took place on the surface of the nanoparticles, whereas BODIPY was encapsulated within the core of the nanoparticles. BODIPY release was found to be pH-dependent. Our results indicate 94 % BODIPY release after 16 h at pH 4, whereas only 2 % were released at pH 7.4. Furthermore, complexation with siRNA against luciferase gene was observed at the surface of PMINPs and gene silencing through its delivery via photochemical internalization (PCI) mechanism was efficient in MDA-MB-231 breast cancer cells expressing stable luciferase.

Periodic mesoporous ionosilica nanoparticles for dual cancer therapy: Two-photon excitation siRNA gene silencing in cells and photodynamic therapy in zebrafish embryos.

Photodynamic therapy (PDT) and photochemical internalization (PCI) are two methods that use light to provoke cell death or disturbance of cellular membranes, respectively, via excitation of a photosensitizer and the formation of reactive oxygen species (ROS). In this context, two-photon excitation (TPE) is of high interest for PCI and/or PDT due to spatiotemporal resolution of two-photon light and deeper penetration of near-infrared light in biological tissues. Here, we report that Periodic Mesoporous Ionosilica Nanoparticles (PMINPs) containing porphyrin groups allow the complexation of pro-apoptotic siRNA. These nano-objects were incubated with MDA-MB-231 breast cancer cells, and TPE-PDT led to significant cell death. Finally, MDA-MB-231 breast cancer cells were pre-incubated with the nanoparticles and then injected in the pericardial cavity of zebrafish embryos. After 24 h, the xenografts were irradiated with femtosecond pulsed laser and the size monitoring by imaging showed a decrease 24 h after irradiation. Pro-apoptotic siRNA was complexed with the nanoparticles and incubation with MDA-MB-231 cells did not lead to cancer cell death in dark conditions, but with two-photon irradiation, TPE-PCI was observed and a synergic effect between pro-apoptotic siRNA and TPE-PDT was noticed, leading to 90% of cancer cell death. Therefore, PMINPs represent an interesting system for nanomedicine applications.