Development of nanoparticles based on amphiphilic cyclodextrins for the delivery of active substances

Although amphiphilic cyclodextrin derivatives (ACDs) serve as valuable building blocks for nanomedicine formulations, their widespread production still encounters various challenges, limiting large-scale manufacturing. This work focuses on a robust alternative pathway using mineral base catalysis to transesterify β-cyclodextrin with long-chain vinyl esters, yielding ACD with modular and controlled hydrocarbon chain grafting. ACDs with a wide range of degrees of substitution (DS) were reliably synthesized, as indicated by extensive physicochemical characterization, including MALDI-TOF mass spectrometry. The influence of various factors, including the type of catalyst and the length of the hydrocarbon moiety of the vinyl ester, was studied in detail. ACDs were assessed for their ability to form colloidal suspensions by nanoprecipitation, with or without PEGylated phospholipid. Small-angle X-ray scattering and cryo-electron microscopy revealed the formation of nanoparticles with distinct ultrastructures depending on the DS: an onion-like structure for low and very high DS, and reversed hexagonal organization for DS between 4.5 and 6.1. We confirmed the furtivity of the PEGylated versions of the nanoparticles through complement activation experiments and that they were well tolerated in-vivo on a zebrafish larvae model after intravenous injection. Furthermore, a biodistribution experiment showed that the nanoparticles left the bloodstream within 10 h after injection and were phagocytosed by macrophages.

Molecular Mechanisms Involved in the Chemical Instability of ONC201 and Methods to Counter Its Degradation in Solution

Glioblastoma is one of the most common and aggressive forms of brain tumor, a rare disease for which there is a great need for innovative therapies. ONC201, a new drug substance, has been used in a compassionate treatment program where the choice of dosage form and regimen have yet to be justified. The prior knowledge needed to anticipate ONC201 stability problems has recently been partially addressed, by (i) showing that ONC201 is sensitive to light and oxidation and (ii) identifying the molecular structures of the main degradation products formed. The aim of the work presented here was to improve our understanding of the degradation pathways of ONC201 using data from ab initio calculations and experimental work to supplement the structural information we already published. The C-H bonds located αto the amine of the tetrahydropyridine group and those located alpha to the imine function of the dihydroimidazole group exhibit the lowest bond dissociation energies (BDEs) within the ONC201 molecule. Moreover, these values drop well below 90 kcal.mol-1 when ONC201 is in an excited state (S1; T1). The structures of the photoproducts we had previously identified are consistent with these data, showing that they would have resulted from radical processes following the abstraction of alpha hydrogens. Concerning ONC201's sensitivity to oxidation, the structures of the oxidation products matched the critical points revealed through mapped electrostatic potential (MEP) and average local ionization energy (ALIE). The data obtained from ab initio calculations and experimental work showed that the reactivity of ONC201 to light and oxidation conditions is highly dependent on pH. While an acidic environment (pH < 6) contributes to making ONC201 quantitatively more stable in solution in the face of oxidation and photo-oxidation, it nevertheless seems that certain chemical groups in the molecule are more exposed to nucleophilic attacks, which explains the variation observed in the profile of degradation products formed in the presence of certain antioxidants tested. This information is crucial to better understand the stability results in the presence of antioxidant agents and to determine the right conditions for them to act.

Human dendritic cell maturation induced by amorphous silica nanoparticles is Syk-dependent and triggered by lipid raft aggregation

BACKGROUND

Synthetic amorphous silica nanoparticles (SAS-NPs) are widely employed in pharmaceutics, cosmetics, food and concretes. Workers and the general population are exposed daily via diverse routes of exposure. SAS-NPs are generally recognized as safe (GRAS) by the Food and Drug Administration, but because of their nanoscale size and extensive uses, a better assessment of their immunotoxicity is required. In the presence of immune "danger signals", dendritic cells (DCs) undergo a maturation process resulting in their migration to regional lymph nodes where they activate naive T-cells. We have previously shown that fumed silica pyrogenic SAS-NPs promote the two first steps of the adaptative immune response by triggering DC maturation and T-lymphocyte response, suggesting that SAS-NPs could behave as immune "danger signals". The present work aims to identify the mechanism and the signalling pathways involved in DC phenotype modifications provoked by pyrogenic SAS-NPs. As a pivotal intracellular signalling molecule whose phosphorylation is associated with DC maturation, we hypothesized that Spleen tyrosine kinase (Syk) may play a central role in SAS-NPs-induced DC response.

RESULTS

In human monocyte-derived dendritic cells (moDCs) exposed to SAS-NPs, Syk inhibition prevented the induction of CD83 and CD86 marker expression. A significant decrease in T-cell proliferation and IFN-γ, IL-17F and IL-9 production was found in an allogeneic moDC:T-cell co-culture model. These results suggested that the activation of Syk was necessary for optimal co-stimulation of T-cells. Moreover, Syk phosphorylation, observed 30 min after SAS-NP exposure, occurred upstream of the c-Jun N-terminal kinase (JNK) Mitogen-activated protein kinases (MAPK) and was elicited by the Src family of protein tyrosine kinases. Our results also showed for the first time that SAS-NPs provoked aggregation of lipid rafts in moDCs and that MβCD-mediated raft destabilisation altered Syk activation.

CONCLUSIONS

We showed that SAS-NPs could act as an immune danger signal in DCs through a Syk-dependent pathway. Our findings revealed an original mechanism whereby the interaction of SAS-NPs with DC membranes promoted aggregation of lipid rafts, leading to a Src kinase-initiated activation loop triggering Syk activation and functional DC maturation.

Fragmentation of DMPC Membranes by a Wedge-Shaped Amphiphilic Cyclodextrin into Bicellar-like Aggregates

Small bilayer lipid aggregates such as bicelles provide useful isotropic or anisotropic membrane mimetics for structural studies of biological membranes. We have shown previously by deuterium NMR that a wedge-shaped amphiphilic derivative of trimethyl βcyclodextrin anchored in deuterated DMPC-d27 bilayers through a lauryl acyl chain (TrimβMLC) is able to induce magnetic orientation and fragmentation of the multilamellar membranes. The fragmentation process fully detailed in the present paper is observed with 20% cyclodextrin derivative below 37 °C, where pure TrimβMLC self-assembles in water into large giant micellar structures. After deconvolution of a broad composite ²H NMR isotropic component, we propose a model where the DMPC membranes are progressively disrupted by TrimβMLC into small and large micellar aggregates depending whether they are extracted from the outer or inner layers of the liposomes. Below the fluid-to-gel transition of pure DMPC-d27 membranes (T_c = 21.5 °C), the micellar aggregates vanish progressively until complete extinction at 13 °C, with a probable release of pure TrimβMLC micelles leaving lipid bilayers in the gel phase doped with only a small amount of the cyclodextrin derivative. Bilayer fragmentation between T_c and 13 °C was also observed with 10% and 5% of TrimβMLC, with NMR spectra suggesting possible interactions of micellar aggregates with fluid-like lipids of the P_β' ripple phase. No membrane orientation and fragmentation was detected with unsaturated POPC membranes, which are able to accommodate the insertion of TrimβMLC without important perturbation. The data are discussed in relation to the formation of possible DMPC bicellar aggregates such as those known to occur after insertion of dihexanoylphosphatidylcholine (DHPC). These bicelles are in particular associated with similar deuterium NMR spectra exhibiting identical composite isotropic components which were never characterized before.

Optimization of experimental conditions by surface enhanced Raman Scattering (SERS) spectroscopy with gold nanoparticles suspensions

Surface Enhanced Raman Scattering (SERS) spectroscopy is a rapid and innovative analysis technique involving metallic nanoparticles (NPs). The interaction between NPs and norepinephrine gives an exaltation of the Raman signal under certain experimental conditions. The control of the signal exaltation, crucial for sensitive analyses, remains one of the main limitations of this technique. The aim of this work is to optimize the exaltation conditions for an optimal SERS signal at two concentrations of norepinephrine (NOR) and spherical gold NPs in suspension. This first work will fix the optimal experimental conditions essential for the development of robust discriminant and quantitative analysis of catecholamine. Two complete 3-factors 3-levels experiment designs were performed at 20 µg.mL^-1 and 100 µg.mL^-1 norepinephrine concentrations, each experiment being repeated 3 times. The optimization factors were the process of synthesis (variation of the quantity of gold and citrate used for the three synthesis SA, SB and SC) and HCl (0.3 M, 0.5 M, 0.7 M) as well as the volume ratio of NPs and norepinephrine (0.5, 2, 3.5) for SERS acquisition. Spectral acquisitions were performed with a handheld Raman spectrometer with an excitation source at 785 nm. For each sample, 31 acquisitions were realized during 3 s every 8 s. The optimization parameter was the intensity of the characteristic band of norepinephrine at 1280 cm^-1. A total of 5,042 spectra were acquired and the pre-treatment selected for all spectra was asymmetric least square combined to a smoothing of Savistsky Golay (ALS - SG). The optimal contact time between norepinephrine and NPs depends on the experimental conditions and was determined for each experiment according to the mean intensity between the three replicates. After interpretation of the experimental designs, the optimal conditions retained were the quantity of gold corresponding to SA and the HCl concentration 0.7 M for the two concentrations of norepinephrine. Indeed, the optimal volume ratio depend on the NOR concentration.

Discriminative and quantitative analysis of norepinephrine and epinephrine by surface-enhanced Raman spectroscopy with gold nanoparticle suspensions

Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique capable of increasing the Raman signal of an analyte using specific nanostructures. The close contact between those nanostructures, usually a suspension of nanoparticles, and the molecule of interest produces an important exaltation of the intensity of the Raman signal. Even if the exaltation leads to an improvement of Raman spectroscopy sensitivity, the complexity of the SERS signal and the numbers of parameters to be controlled allow the use of SERS for detection rather than quantification. The aim of this study was to develop a robust discriminative and quantitative analysis in accordance with pharmaceutical standards. In this present work, we develop a discriminative and quantitative analysis based on the previous optimized parameters obtained by the design of experiments fixed for norepinephrine (NOR) and extended to epinephrine (EPI) which are two neurotransmitters with very similar structures. Studying the short evolution of the Raman signal intensity over time coupled with chemometric tools allowed the identification of outliers and their removal from the data set. The discriminant analysis showed an excellent separation of EPI and NOR. The comparative analysis of the data showed the superiority of the multivariate analysis after logarithmic transformation. The quantitative analysis allowed the development of robust quantification models from several gold nanoparticle batches with limits of quantification of 32 µg/mL for NOR and below 20 µg/mL for EPI even though no Raman signal is observable for such concentrations. This study improves SERS analysis over ultrasensitive detection for discrimination and quantification using a handheld Raman spectrometer.

Synthetic amorphous silica nanoparticles promote human dendritic cell maturation and CD4 + T-lymphocyte activation

Innate immune cells such as dendritic cells (DCs) sense and engulf nanomaterials potentially leading to an adverse immune response. Indeed, as described for combustion-derived particles, nanomaterials could be sensed as danger signals, enabling DCs to undergo a maturation process, migrate to regional lymph nodes and activate naive T-lymphocytes. Synthetic amorphous silica nanoparticles (SAS-NPs) are widely used as food additives, cosmetics, and construction materials. This work aimed to evaluate in vitro the effects of manufactured SAS-NPs, produced by thermal or wet routes, on human DCs functions and T-cell activation. Human monocyte-derived DCs (moDCs) were exposed for 16 hours to three endotoxin-free test materials: fumed silica NPs from Sigma-Aldrich (#S5505) or the JRC Nanomaterial Repository (NM-202) and colloidal Ludox®TMA NPs. Cell viability, phenotypical changes, cytokines production, internalization, and allogeneic CD4+ T-cells proliferation were evaluated. Our results showed that all SAS-NPs significantly upregulated the surface expression of CD86 and CD83 activation markers. Secretions of pro-inflammatory cytokines (CXCL-8 and CXCL-12) were significantly enhanced in a dose-dependent manner in the moDCs culture supernatants by all SAS-NPs tested. In an allogeneic co-culture, fumed silica-activated moDCs significantly increased T-lymphocyte proliferation at all T-cell:DC ratios compared to unloaded moDCs. Moreover, analysis of co-culture supernatants regarding the production of T-cell-derived cytokines showed a significant increase of IL-9 and IL-17A and F, as well as an upregulation of IL-5, consistent with the pro-inflammatory phenotype of treated-moDCs. Taken together, these results suggest that SAS-NPs could induce functional moDCs maturation and play a role in the immunization process against environmental antigens.

A mathematical approach to deal with nanoparticle polydispersity in surface enhanced Raman spectroscopy to quantify antineoplastic agents

Antineoplastic agents are, for most of them, highly toxic drugs prepared at hospital following individualized prescription. To protect patients and healthcare workers, it is important to develop analytical tools able to identify and quantify such drugs on a wide concentration range. In this context, surface enhanced Raman spectroscopy (SERS) has been tested as a specific and sensitive technique. Despite the standardization of the nanoparticle synthesis, a polydispersity of nanoparticles in the suspension and a lack of reproducibility persist. This study focuses on the development of a new mathematical approach to deal with this nanoparticle polydispersity and its consequences on SERS signal variability through the feasibility of 5-fluorouracil (5FU) quantification using silver nanoparticles (AgNPs) and a handled Raman spectrophotometer. Variability has been maximized by synthetizing six different batches of AgNPs for an average size of 24.9 nm determined by transmission electron microscopy, with residual standard deviation of 17.0%. Regarding low performances of the standard multivariate data processing, an alternative approach based on the nearest neighbors were developed to quantify 5FU. By this approach, the predictive performance of the 5FU concentration was significantly improved. The mean absolute relative error (MARE) decreased from 16.8% with the traditional approach based on PLS regression to 6.30% with the nearest neighbors approach (p-value < 0.001). This study highlights the importance of developing mathematics adapted to SERS analysis which could be a step to overcome the spectral variability in SERS and thus participate in the development of this technique as an analytical tool in quality control to quantify molecules with good performances, particularly in the pharmaceutical field.

New generation of supramolecular mixtures: Characterization and solubilization studies

In this work, a series of novel low melting mixtures (LMM) based on cyclodextrins (CD) and levulinic acid and inspired by the deep eutectic solvents (DES), were prepared. These supramolecular mixtures are the first reported CD-based mixtures that are liquid at room temperature. Density, viscosity and rheological measurements as well as differential scanning calorimetry and thermogravimetric analysis were performed to characterize these new LMM. Nuclear magnetic resonance (NMR) spectroscopy was used to monitor their stability. Furthermore, their ability to solubilize trans-anethole (AN) and related essentials oils were evaluated by static headspace-gas chromatography (SH-GC), in comparison with water. AN was up to 1300 times more soluble in the CD-based LMM than in water. Finally, multiple headspace extraction (MHE) was used to monitor the release of AN from these LMM. After 10 extractions, 20 to 40% of AN was released from the studied LMM, while 70% was released from water. The new CD-based LMM have potential applications for solubilization and delivery of poorly soluble drugs.

Cyclodextrin complexation studies as the first step for repurposing of chlorpromazine

The antipsychotic drug chlorpromazine (CPZ) has potential for the treatment of acute myeloid leukemia, if central nervous system side-effects resulting from its passage through the blood-brain barrier can be prevented. A robust drug delivery system for repurposed CPZ would be drug-in-cyclodextrin-in-liposome that would redirect the drug away from the brain while avoiding premature release in the circulation. As a first step, CPZ complexation with cyclodextrin (CD) has been studied. The stoichiometry, binding constant, enthalpy, and entropy of complex formation between CPZ and a panel of CDs was investigated by isothermal titration calorimetry (ITC). All the tested CDs were able to include CPZ, in the form of 1:1, 1:2 or a mixture of 1:1 and 1:2 complexes. In particular, a substituted γ-CD, sugammadex (the octasodium salt of octakis(6-deoxy-6-S-(2-carboxyethyl)-6-thio)cyclomaltooctaose), formed exclusively 1:2 complexes with an extremely high association constant of 6.37 × 10⁹ M^-2. Complexes were further characterized by heat capacity changes, one- and two-dimensional (ROESY) nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics simulations. Finally, protection of CPZ against photodegradation by CDs was assessed. This was accelerated rather than reduced by complexation with CD. Altogether these results provide a molecular basis for the use of CD in delayed release formulations for CPZ.

How to Address the Adjuvant Effects of Nanoparticles on the Immune System

As the nanotechnology market expands and the prevalence of allergic diseases keeps increasing, the knowledge gap on the capacity of nanomaterials to cause or exacerbate allergic outcomes needs more than ever to be filled. Engineered nanoparticles (NP) could have an adjuvant effect on the immune system as previously demonstrated for particulate air pollution. This effect would be the consequence of the recognition of NP as immune danger signals by dendritic cells (DCs). The aim of this work was to set up an in vitro method to functionally assess this effect using amorphous silica NP as a prototype. Most studies in this field are restricted to the evaluation of DCs maturation, generally of murine origin, through a limited phenotypic analysis. As it is essential to also consider the functional consequences of NP-induced DC altered phenotype on T-cells biology, we developed an allogeneic co-culture model of human monocyte-derived DCs (MoDCs) and CD4+ T-cells. We demonstrated that DC: T-cell ratios were a critical parameter to correctly measure the influence of NP danger signals through allogeneic co-culture. Moreover, to better visualize the effect of NP while minimizing the basal proliferation inherent to the model, we recommend testing three different ratios, preferably after five days of co-culture.

Helically shaped cation receptor: design, synthesis, characterisation and first application to ion transport

An helicene-like receptor is able to transport K⁺ across lipid membrane.

Alumina nanoparticles size and crystalline phase impact on cytotoxic effect on alveolar epithelial cells after simple or HCl combined exposures

Applications using alumina nanoparticles (Al₂O₃ NPs) have incredibly increased in different fields of activity. In defense and aerospace fields, solid composite propellants use leads to complex combustion aerosols emissions containing high concentrations of Al₂O₃ NPs and hydrogen chloride gas (HCl). To better characterize potential hazard resulting from exposure to these aerosols, this study assesses cytotoxic effects of mixtures containing both compounds on human pulmonary alveolar epithelial cells (A549 cell line) after 24 h exposures. After all co-exposures cell viability was >80%. However co-exposures decrease normalized real-time cell index. Significant decreases of intracellular reduced glutathione pool were also observed after co-exposures to γ-10 nm or γ/δ-13 nm Al₂O₃ NPs and HCl. Co-incubations with γ/δ-13 nm or γ-500 nm Al₂O₃ particles and HCl induced significant DNA double-strand breaks increases. Moreover all co-exposures and HCl alone disrupted cell cycle (increased G1 phase cells). Transmission Electron Microscopy (TEM) observations revealed γ/δ-13 nm Al₂O₃NPs adsorption and internalization in cell cytoplasm only, suggesting indirect genotoxic effects. According to our results Al₂O₃ particles/HCl mixtures can induce cytotoxic effects and Al₂O₃ size and crystallinity are two main parameters influencing cytotoxic mechanisms.

New nanoparticles obtained by co-assembly of amphiphilic cyclodextrins and nonlamellar single-chain lipids: Preparation and characterization

This work aimed at preparing new nanoscale assemblies based on an amphiphilic bio-esterified β-cyclodextrin (β-CD), substituted at the secondary face with n-decanoic fatty acid chains (β-CD-C₁₀), and monoolein (MO) as new carriers for parenteral drug delivery. Stable binary (β-CD-C₁₀/MO) and ternary (β-CD-C₁₀/MO/stabilizer) nanoscale assemblies close to 100nm in size were successfully prepared in water by the solvent displacement method. The generated nanoparticles were fully characterized by dynamic light scattering, transmission electron microscopy, small-angle X-ray scattering, residual solvent analysis, complement activation and the contribution of each formulation parameter was determined by principal component analysis. The β-CD-C₁₀ units were shown to self-organize into nanoparticles with a hexagonal supramolecular packing that was significantly modulated by the molar ratio of the constituents and the presence of a steric or electrostatic stabilizer (DOPE-PEG₂₀₀₀ or DOPA/POPA, respectively). Indeed, nanoparticles differing in morphology and in hexagonal lattice parameters were obtained while the co-existence of multiple mesophases was observed in some formulations, in particular for the β-CD-C₁₀/MO/DOPA and β-CD-C₁₀/MO/POPA systems. The mixed β-CD-C₁₀/MO/DOPE-PEG₂₀₀₀ nanoparticles (49:49:2 in mol%) appeared to be the most suitable for use as a drug delivery system since they contained a very low amount of residual solvent and showed a low level of complement C3 activation.

Self-Assembly of Amphiphilic Biotransesterified β-Cyclodextrins: Supramolecular Structure of Nanoparticles and Surface Properties

A series of β-cyclodextrin (βCD) amphiphilic derivatives with varying degrees of substitution were prepared by acylating βCDs on their secondary face using thermolysin to catalyze the transesterification. After dissolution in acetone, the βCD-C_n derivatives (n = 8, 10, 12, 14) were nanoprecipitated in water, where they self-organized into structured particles that were characterized using cryo-transmission electron microscopy (cryo-TEM) images and small-angle X-ray scattering (SAXS) data. Two types of morphologies and ultrastructures were observed depending on the total degree of substitution (TDS) of the parent derivative. The molecules with TDS < 5 formed nanospheres with a multilamellar organization, whereas those with TDS > 5 self-assembled into barrel-like (n = 8, 10, 12) or more tortuous (n = 14) particles with a columnar inverse hexagonal structure. In particular, faceted βCD-C₁₄ particles (TDS = 7) appeared to be composed of several domains with different orientations that were separated by sharp interfaces. Ultrastructural models were proposed on the basis of cryo-TEM images and the analysis of the contrast distribution in different projections of the lattice. Complementary compression isotherm experiments carried out at the air-water interface also suggested that differences in the molecular conformation of the series of derivatives existed depending on whether TDS was lower or higher than 5.

Effect of growth hormone and IgG aggregates on dendritic cells activation and T-cells polarization

Patients treated with therapeutic biological products (BP) frequently develop anti-drug antibodies (ADA) with potential neutralizing capacities leading to loss of clinical response or serious side effects. BP aggregates have been suggested to promote immunogenicity, thus enhancing ADA production. Dendritic cells (DC) are key effectors in T-cell and B-cell fates, and the subsequent generation of immunogenicity. The objective of this work was to determine if BP aggregates can participate to DC maturation and T-cell activation. We compared aggregates from three different proteins: human growth hormone (hGH), Rituximab, a chimeric anti-CD20 antibody and a serum-purified human IgG1. All three proteins underwent a stir stress, generating comparable populations of aggregated particles. Maturation of human monocyte-derived DC (moDC) upon exposure to native BPs or aggregates was evaluated in vitro. Results showed that hGH aggregates induced an increased expression of moDC co-stimulation markers, and augmented levels of IL-6, IL-8, IL-12p40, CCL2, CCL3, CCL4 and CXCL10. Both antibodies aggregates were also able to modify DC phenotype, but cytokine and chemokine productions were seen only with IL-6, IL-8, IL-12p40 and CXCL10. Aggregates-treated moDC enhanced allogenic T-cell proliferation and cytokines production, suggesting Th1 polarization with hGH, and mixed T-cell responses with antibodies aggregates. These results showed that BP aggregates provoked DC maturation, thus driving adaptive T-cell responses and polarization.