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In this work, we used an original experimental setup to examine the behavior of insoluble monolayers made with pH-sensitive lipids. Two kinds of unsaturated lipids were chosen: a cationic one (lipid 1) bearing an ammonium headgroup and an anionic one (lipid 2) terminated with an acidic phenol group. The lipids were deposited onto an air bubble interface maintained in an aqueous phase and, after stabilization, were subjected to a series of compressions performed at different pH values. These experiments disclosed a gradual increase in the specific area per molecule when lipids were neutralized. Imposing a pH variation at constant bubble volume also provided surface pressure profiles that confirmed this molecular behavior. As complementary characterization, dilatational rheology disclosed a phase transition from a purely elastic monophasic system to a viscoelastic two-phase system. We hypothesized that this unexpected increase in the specific area with lipid neutralization is related to the presence of unsaturations in each of the two branches of the hydrophobic tails that induce disorder, thereby increasing the molecular area at the interface. Application of the two-dimensional Volmer equation of state allowed the generation of quantitative values for the specific areas that showed variations with pH. It also allowed the determination of apparent pKa values, which are affected by both the electrostatic potential within the monolayer and the affinity of the lipid polar head for the aqueous phase.

Nano-emulsions are defined as stable oil droplets sizing below 300 nm. Their singular particularity lies in the loading capabilities of their oily core, much higher than other kinds of carrier. On the other hand, functionalizing the dynamic oil/water interface, to date, has remained a challenge. To ensure the best anchoring of the reactive functions onto the surface of the droplets, we have designed specific amphiphilic polymers (APs) based on poly(maleic anhydride-alt-1-octadecene), stabilizing the nano-emulsions instead of surfactants. Aliphatic C18 chains of the APs are anchored in the droplet core, while the hydrophilic parts of the APs are poly(ethylene glycol) (PEG) chains. In addition, PEG chains are terminated with reactive (i) azide functions in order to prove the concept of the droplet decoration with clickable rhodamine (Rh-DBCO, specifically synthesized for this study), or (ii) biotin functions to verify the potential droplet functionalization with fluorescent streptavidin (streptavidin-AF-488). This study describes AP synthesis, physico-chemical characterization of the functional droplets (electron microscopy), and finally fluorescence labeling and droplet decoration. To conclude, these APs constitute an interesting solution for the stable functionalization of nano-emulsion droplets, paving a new way for the applications of nano-emulsions in targeting drug delivery.

The eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) formulation with a ratio of 6:1 is a potent stimulator of the endothelial formation of nitric oxide (NO). The aim of the study was to investigate whether nanoencapsulation of EPA:DHA 6:1 followed by coating with gum increases its biological activity. Vascular reactivity was assessed using porcine coronary artery rings, the formation of NO in cultured endothelial cells (ECs) using DAF-FM and indirectly by platelet aggregation studies. Coated EPA:DHA 6:1 nanoparticles induced sustained relaxations of coronary artery rings that were greater in rings with than in those without endothelium, and more pronounced than with the native form. Treatment of ECs with coated EPA:DHA 6:1 nanoparticles caused greater and more sustained formation of NO and enhanced their anti-aggregatory effects. Thus, nanoencapsulation of EPA:DHA 6:1 is an attractive strategy to enhance the beneficial effect at the vascular endothelium.

Nanoemulsions (NEs) are biocompatible lipid nanoparticles composed of an oily core stabilized by a surfactant shell. It is acknowledged that the surface decoration with poly(ethylene glycol), through the use of nonionic surfactants, confers high stealth in biological medium with reduced nonspecific interactions. Tracking individual NE by fluorescence microscopy techniques would lead to a better understanding of their behavior in cells and thus require the development of bright single particles with enhanced photostability. However, the understanding of the relationship between the physicochemical properties and chemical composition of the NEs, on the one hand, and its fluorescence properties of encapsulated dyes, on the other hand, remains limited. Herein, we synthesized three new dioxaborine barbituryl styryl (DBS) dyes that displayed high molar extinction coefficients (up to 120 000 M

International audience; Endothelial senescence has been identified as an early event in the development of endothelial dysfunction, a hallmark of cardiovascular disease. This study developed theranostic nanocarriers (NC) decorated with VCAM-1 antibodies (NC-VCAM-1) in order to target cell surface VCAM-1, which is overexpressed in senescent endothelial cells (ECs) for diagnostic and therapeutic purposes. Incubation of Ang IIinduced premature senescent ECs or replicative senescent ECs with NC-VCAM-1 loaded with lipophilic fluorescent dyes showed higher fluorescence signals than healthy EC, which was dependent on the NC size and VCAM-1 antibodies concentration, and not observed following masking of VCAM-1. NC loaded with omega 3 polyunsaturated fatty acid (NC-EPA:DHA6:1) were more effective than native EPA:DHA 6:1 to prevent Ang II-induced VCAM-1 and p53 upregulation, and SA-β-galactosidase activity in coronary artery segments. These theranostic NC might be of interest to evaluate the extent and localization of endothelial senescence and to prevent pro-senescent endothelial responses.

Nano-emulsion consists of a dispersion of oil droplets sizing below 200 nm, in aqueous continuous phase, and generally stabilized by low-molecular-weight surfactants. These stable nano-carriers are able to encapsulate and transport lipophilic molecules poorly soluble in water. However, the question on the leakage and release mechanisms of an active pharmaceutical ingredient, from oil nano-droplets to an acceptor medium has not been clearly addressed. Herein, we developed a simple fluorescence approach based on self-quenching of lipophilic fluorophore-based on Nile Red (NR668) to monitor cargo transfer from lipid nano-droplets to the acceptor medium. In this method, the fluorophore release can be monitored by the increase in its fluorescence quantum yield and the blue shift in its emission spectrum. The studies of the release process allow emphasizing an important role of the bulk aqueous medium in controlling the droplet to droplet fluorophore transfer and the attained equilibrium. The developed methodology could be applied to monitor release of other lipophilic dyes and it could help to better understand the cargo release from nanocarriers.

International audience; Efficient and safe delivery of anticancer drugs such as 5-fluorouracil (5-FU) is still a challenge in chemotherapy. The combination of polymers with a luminescent probe offers a promising venue to develop nanoobjects for theranostics. Herein, upconversion nanoparticles (UCNPs) decorated with polymers based on N-(2-hydroxypropyl) methacrylamide at their surface were investigated as potential carriers of 5-FU. The hyperbranched topology of the polymer offered a higher loading capacity of the polymer shell as compared to this linear analog even though the loading in 5-FU remained low and its release was fast (few hours). To overcome these limitations, 5-FU was conjugated to the polymer through esterification leading to a four-fold increase of the loading and a more sustained release over few days. The introduction of branching points with a disulfide bridge on the polymer afforded nanohybrids susceptible to degradation in the reductive environment of cancer cells. The degradation of the polymer was confirmed by incubating the polymer with dithiothreitol. These results pave the way to theranostics through the use of luminescent properties of UCNPs and the tuning of the polymer architecture.

International audience; Hyperbranched poly(N-(2-hydroxypropyl) methacrylamide)s grafted on upconversion nanoparticles (UCNPs) were prepared by surface-initiated self-condensing vinyl RAFT copolymerization from the surface of UCNPs modified with a RAFT chain transfer agent. The effect of the grafting density in RAFT chain transfer agent on UCNPs and the concentration in transmer were investigated. The propagation of the polymerization was strongly affected by termination and transfer reactions associated to the high local concentration in propagating chains due to the immobilization of the polymer chains at the surface of UCNPs and increased number of active centers during the polymerization, but also to the hopping and rolling mechanisms related to the surface-initiated RAFT polymerization. The development of such nanohybrids opens the way to novel nano-objects for biomedical imaging and theranostics.

Nanosized gel particles, so-called nanogels, have attracted substantial interest in different application fields, thanks to their controllable and three-dimensional physical structure, good mechanical properties and potential biocompatibility. Literature reports many technologies for their preparation and design, however a recurrent limitation remains in their broad size distributions as well as in the poor size control. Therefore, the monodisperse and size-controlled nanogels preparation by simple process –like emulsification– is a real challenge still in abeyance to date. In this study we propose an original low energy emulsification approach for the production of monodisperse nanogels, for which the size can be finely controlled in the range 30 to 200 nm. The principle lies in the fabrication of a direct nano-emulsion containing both oil (medium chain triglycerides) and a bi-functional acrylate monomer. The nanogels are thus formed in situ upon UV irradiation of the droplet suspension. Advantage of such modification of the oil nano-carriers are the potential modulation of the release of encapsulated drugs, as a function of the density and/or properties of the polymer chain network entrapped in the oil nano-droplets. This hypothesis was confirmed using a model of hydrophobic drug –ketoprofen– entrapped into the nanogels particles, along with the study of the release profile, carried out in function of the nature of the monomers, density of polymer chains, and different formulation parameters.

The prevalence of nosocomial infections due to multidrug resistant (MDR) bacterial strains is associated with high morbidity and mortality. Folk medicine and ethnopharmacological data can provide a broad range of plants with promising antimicrobial activity. Triphala, an Ayurvedic formula composed of three different plants: Terminalia chebula Retz., Terminalia bellirica (Gaertn.) Roxb. (Combretaceae), and Phyllanthus emblica L. (Phyllanthaceae), is used widely for various microbial infections. Various extraction techniques were applied in the extraction of the biologically active constituents of Triphala in order to compare their efficiency. Microwave-assisted extraction (MAE) was shown to be the most efficient method based on yield, extraction time, and selectivity. The Triphala hydroalcoholic extract (TAE) has been chemically characterized with spectroscopic and chromatographic techniques. Triphala hydroalcoholic extract was evaluated alone or with carvacrol. Different drug formulations including cream and nanoemulsion hydrogel were prepared to assess the antimicrobial activity against selected microorganism strains including Gram-positive and Gram-negative bacteria and fungi. We used a lipophilic oil of carvacrol (5 mg/mL) and a hydrophilic TAE (5 mg/mL) ingredient in a dosage form. Two solutions were created: hydrogel containing nanoemulsion as a lipophilic vector dispersed in the gel as a hydrophilic vehicle and a cream formulation, an oil-in-water emulsion. In both cases, the concentration was 250 mg of active ingredient in 50 mL of final formulation. The formulas developed were stable from a physical and chemical perspective. In the nanoemulsion hydrogel, the oil droplet size ranged from 124 to 129 nm, with low polydispersity index (PdI) 0.132 ± 0.013 and negative zeta potential −46.4 ± 4.3 mV. For the cream, the consistency factor (cetyl alcohol and white wax) induced immobilization of the matrix structure and the stability. Triphala hydroalcoholic extract in drug nanoformulation illustrated might be an adjuvant antimicrobial agent for treating various microbial infections.

International audience; In general, nano-emulsions are submicron droplets composed of liquid oil phase dispersed in liquid aqueous bulk phase. They are stable and very powerful systems when it regards the encapsulation of lipophilic compounds and their dispersion in aqueous medium. On the other hand, when the properties of the nano-emulsions aim to be modified, e.g. for changing their surface properties, decorating the droplets with targeting ligands, or modifying the surface charge, the dynamic liquid / liquid interfaces make it relatively challenging. In this study, we have explored the development of nano-emulsions which were not anymore stabilized with a classical low-molecular weight surfactant, but instead, with an amphiphilic polymer based on poly(maleic anhydride-alt-1-octadecene) (PMAO) and Jeffamine®, a hydrophilic amino-terminated PPG/PEG copolymer. Using a polymer as stabilizer is a potential solution for the nano-emulsion functionalization, ensuring the droplet stabilization as well as being a platform for the droplet decoration with ligands (for instance after addition of function groups in the terminations of the chains). The main idea of the present work was to understand if the spontaneous emulsification –commonly performed with nonionic surfactants– can be transposed with amphiphilic polymers, and a secondary objective was to identify the main parameters impacting on the process. PMAO was modified with two different Jeffamine®, additionally differentoils and different formulation conditions were evaluated. As a control, the parent monomer, octadecyl succinic anhydride (OSA) was also modified and studied in the similar way as that of polymer. The generated nano-emulsions were mainly studied by dynamic light scattering and electron microscopy, that allows discriminating the crucial parameters in the spontaneous process, originally conducted with polymers as only stabilizer.

Lipid nanocarriers are considered as promising candidates for drug delivery and cancer targeting because of their low toxicity, biodegradability and capacity to encapsulate drugs and/or contrasting agents. However, their biomedical applications are currently limited because of a poor understanding of their integrity in vivo. To address this problem, we report on fluorescent nano-emulsion droplets of 100 nm size encapsulating lipophilic near-infrared cyanine 5.5 and 7.5 dyes with a help of bulky hydrophobic counterion tetraphenylborate. Excellent brightness and efficient Förster Resonance Energy Transfer (FRET) inside lipid NCs enabled for the first time quantitative fluorescence ratiometric imaging of NCs integrity directly in the blood circulation, liver and tumor xenografts of living mice using a whole-animal imaging set-up. This unique methodology revealed that the integrity of our FRET NCs in the blood circulation of healthy mice is preserved at 93% at 6 h of post-administration, while it drops to 66% in the liver (half-life is 8.2 h). Moreover, these NCs show fast and efficient accumulation in tumors, where they enter in nearly intact form (77% integrity at 2 h) before losing their integrity to 40% at 6 h (half-life is 4.4 h). Thus, we propose a simple and robust methodology based on ratiometric FRET imaging in vivo to evaluate quantitatively nanocarrier integrity in small animals. We also demonstrate that nano-emulsion droplets are remarkably stable nano-objects that remain nearly intact in the blood circulation and release their content mainly after entering tumors., Graphical abstract Image 1

Introduction The omega 3 polyunsaturated fatty acid (PUFAs) formulation containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with a 6:1 ratio is a potent inducer of endothelium-dependent nitric oxide (NO)-mediated vasorelaxation that also improves ageing-related and angiotensin II-induced endothelial dysfunction in rats. Purpose Since PUFAs are unstable, the possibility that nanoencapsulation of EPA:DHA 6:1 followed by coating potentiates the bioactivity was evaluated. Methods EPA:DHA 6:1 was emulsified in water phase and coated with proteins and gum derivatives or used in native form. Changes in isometric tension of porcine coronary artery rings were determined using organ chambers. The role of NO was assessed using Nw-nitro-L-arginine (L-NA, NO synthase inhibitor), prostanoids using indomethacin (Indo, COX inhibitor) and endothelium-derived hyperpolarization (EDH) using TRAM-34 and UCL-1684 (Ca2 + -dependent potassium channel inhibitors). Results Coated EPA:DHA 6:1 nanoparticles (NP) caused in a concentration-dependent manner endothelium-dependent relaxations that were more sustained than those of the native form. At 0.3%, coated and native forms induced 56.6 ± 2.8% and 51.1 ± 1.5%relaxations at 10 min, and 93.8 ± 2.1% and 35.1 ± 1.7% at 60 min, respectively. The response to the coated EPA:DHA 6:1 NP was inhibited by L-NA and not affected by Indo, TRAM-34 plus UCL-1684, and by the previous incubation of rings with another oil (corn oil 0.3%). In contrast, L-NA, Indo, and TRAM-34 plus UCL-1684 inhibited the relaxation to EPA:DHA 6:1. Conclusion Nanoencapsulation of EPA:DHA 6:1 followed by coating perpetuated their ability to cause endothelium-dependent relaxation of coronary artery rings that is exclusively mediated by NO. In contrast, the relaxing activity of the native form involved NO, EDH and vasorelaxant prostanoids. Therefore, coated EPA:DHA 6:1 NP appear to be an attractive approach to enhance the vasoprotective effect of omega 3 PUFAs.

Introduction Endothelial senescence has been identified as an early event promoting the development of endothelial dysfunction (ED), a hallmark of vascular ageing and major cardiovascular diseases. In vivo, senescent endothelial cells (EC) appear initially at arterial sites at risk characterized by disturbed flow and low shear stress (i.e., bifurcations and curvatures) compared to those at low risk characterized by laminar flow and a high level of shear stress (i.e., aorta). Objective The aim is to develop fluorescent nano-carriers (NC) to target a cell surface protein up-regulated in senescent ECs, for diagnostic purposes. Method NC with a lipid core containing a fluorescent probe (NR668 or Cy5.5 derivative) stabilized by a polymer scaffold and decorated with VCAM-1 antibodies (NC-VCAM-1) were applied to different models of EC senescence in cultured porcine coronary artery (premature senescence induced by angiotensin II and replicative senescence observed at passage P3). The fluorescence signal was visualized by confocal microscopy. Results Both models of EC senescence demonstrated higher levels of senescence-associated beta-galactosidase activity, senescence markers and VCAM-1 than healthy EC at P1. Incubation of either P3 EC or Ang II-treated P1 EC with fluorescent NC-VCAM-1 showed a higher level of fluorescence than P1 EC. The EC-related NC-VCAM-1 fluorescent signal is abolished by the previous incubation of EC with an antibody directed against VCAM-1, demonstrating the ability to target cell surface VCAM-1. The highest level of NC-VCAM-1 fluorescence was observed with NC with an average diameter below 100 nm and at 37 °C. Conclusion The present findings indicate that fluorescent NC-VCAM-1 allow the detection of senescent EC. Thus, using fluorescent functionalized NC targeting a senescence-associated cell surface protein appears to be an attractive strategy to evaluate the burden of EC senescence, which promotes ED and, ultimately, cardiovascular events.

The purpose of this study was to develop a pH-thermosensitive oral chitosan-based hydrogels, able to release phenobarbital in the small intestine of the newborn. Phenobarbital is an active drug used in neonatal treatment of epilepsy. pH-thermosensitive hydrogels will improve its bioavailability and therapeutic efficiency with less side effects. This study allowed us to understand the free energy variation at the interface between chitosan chains themselves and the surrounding available molecules with its interactions behavour. Indeed, inverted tube method was used to prepare hydrogels containing 2.45 and 2.55% of chitosan, eudragitE100 and phenobarbital at 37+/-1°C via sol-gel transition. The characterization of their morphology was done by using XL SIRION 200 FEG SEM. In addition, conductivity, refractive index and density’s values were determinated. The phenobarbital release mechanism from hydrogels at different pH values, simulating the gastrointestinal tract of the newborn was also studed. UV / visible spectrophotometer SHIMADZU from the UV-2400PC series was used to determine the phenobarbital released amount as a function of time. The results showed that sol-gel transition time decreases when the chitosan concentration increases. In addition, it showed that the hydrogels structure was heterogeneous and the phenobarbital released amount were more important at pH simulating the small intestine at 2.45% of chitosan, final solution’s pH6.85 and with the presence of eudragitE100. These results were confirmed by conductivity’s values. The sols and hydrogels had a comparable refractive index and density’s values. The Korsmeyer-Peppas model was used to fit the phenobarbital release profiles. In short, the hydrogels formulated lend themselves to a phenobarbital pulsatile release usable in the newborn. The phenobarbital release profiles fitting makes possible to predict the phenobarbital amounts, which will be released at the action sites according to the need.

Noninvasive diagnostic by imaging combined with a contrast agent (CA) is by now the most used technique to get insight into human bodies. X-ray and magnetic resonance imaging (MRI) are widely used technologies providing complementary results. Nowadays, it seems clear that bimodal CAs could be an emerging approach to increase the patient compliance, accessing different imaging modalities with a single CA injection. Owing to versatile designs, targeting properties, and high payload capacity, nanocarriers are considered as a viable solution to reach this goal. In this study, we investigated efficient superparamagnetic iron oxide nanoparticle (SPION)-loaded iodinated nano-emulsions (NEs) as dual modal injectable CAs for X-ray imaging and MRI. The strength of this new CA lies not only in its dual modal contrasting properties and biocompatibility, but also in the simplicity of the nanoparticulate assembling: iodinated oily core was synthesized by the triiodo-benzene group grafting on vitamin E (41.7% of iodine) via esterification, and SPIONs were produced by thermal decomposition during 2, 4, and 6 h to generate SPIONs with different morphologies and magnetic properties. SPIONs with most anisotropic shape and characterized by the highest r2/ r1 ratio once encapsulated into iodinated NE were used for animal experimentation. The in vivo investigation showed an excellent contrast modification because of the presence of the selected NEs, for both imaging techniques explored, that is, MRI and X-ray imaging. This work provides the description and in vivo application of a simple and efficient nanoparticulate system capable of enhancing contrast for both preclinical imaging modalities, MRI, and computed tomography.

We present a two-step process to produce dry-state Ketoprofen-loaded poly(methyl methacrylate) nanoparticles (NPs) with controllable size and tunable drug release profile. A colloidal suspension of drug-loaded nanoparticles was first obtained from a nanoprecipitation process and then transferred into a commercial spray dryer. Three micromixers of different designs and mixing principles (molecular diffusion and impact mixing) were tested. After the first step, highly monomodal NPs in the size range 100 to 210 nm were obtained as seen by the low polydispersity index value (ca. PDI ∼ 0.2) returned by a dynamic light scattering detector. Physicochemical properties, encapsulation efficiency/ratio and drug release kinetics of NPs before and after drying were determined. For similar operating conditions, the best micromixer tested (impact mixing) allowed concluding that the NPs size was not significantly affected by the spray drying while encapsulation parameters and drug release rate were slightly decreased compared to the non spray-dried NPs. A sustained drug release was observed over 6 h and the drug release rate (up to 70%) was found to vary with the size of the NPs which in turn was a function of the flow rate ratio between the polymer solution and the non-solvent solution.

In this paper, superparamagnetic iron oxide nano particles (SPIONs, around 6 nm) encapsulated in poly(methyl methacrylate) nanoparticles (PMMA NPs) with controlled sizes ranging from 100 to 200 nm have been successfully produced. The hybrid polymeric NPs were prepared following two different methods: (1) nanoprecipitation and (2) nanoemulsification evaporation. These two methods were implemented in two different microprocesses based on the use of an impact jet micromixer and an elongational-flow microemulsifier. SPIONs-loaded PMMA NPs synthesized by the two methods presented completely different physicochemical properties. The polymeric NPs prepared with the micromixer-assisted nanoprecipitation method showed a heterogeneous dispersion of SPIONs inside the polymer matrix, an encapsulation efficiency close to 100 wt %, and an irregular shape. In contrast, the polymeric NPs prepared with the microfluidic-assisted nanoemulsification evaporation method showed a homogeneous dispersion, an almost complete encapsulation, and a spherical shape. The properties of the polymeric NPs have been characterized by dynamic light scattering, thermogravimetric analysis, and transmission electron microscope. In vitro cytotoxicity assays were also performed on the nanohybrids and pure PMMA NPs.

Understanding the release of drugs and contrast agents from nanocarriers is fundamental in the development of new effective nanomedicines. However, the commonly used method based on dialysis frequently fails to quantify the release of molecules poorly soluble in water, and it is not well-suited for in situ measurements in biological media. Here, we have developed a new methodology for quantifying the release of fluorescent molecules from lipid nanocarriers (LNCs) using fluorescence correlation spectroscopy (FCS). LNCs based on nanoemulsion droplets, encapsulating the hydrophobic Nile red derivative NR668 as a model cargo, were used. Our studies revealed that the standard deviation of fluorescence fluctuations in FCS measurements depends linearly on the dye loading in the nanocarriers, and it is insensitive to the presence of less-bright molecular emissive species in solution. In sharp contrast, classical FCS parameters, such as the number and the brightness of emissive species, are strongly influenced by the fluorescence of molecular species in solution. Therefore, we propose to use the standard deviation of fluorescence fluctuations for the quantitative analysis of dye release from nanocarriers, which is unaffected by the “parasite” fluorescence of the released dyes or the auto-fluorescence of the medium. Using this method, we found that LNCs remain intact in water, whereas in serum medium, they release their content in a temperature-dependent manner. At 37 °C, the release was relatively slow reaching 50% only after 6 h of incubation. The results are corroborated by qualitative observations based on Förster resonance energy transfer between two different encapsulated dyes. The developed method is simple because it is only based on the standard deviation of fluorescence fluctuations and, in principle, can be applied to nanocarriers of different types.

In current study, we report on the synthesis of core-shell microparticles for dual drug delivery by means of a two co-axial microfluidic device and online UV assisted free radical polymerization. Before developing pH-sensitive particles, ketoprofen loaded poly(methyl acrylate) core-ranitidine HCl loaded poly(acrylamide) shell particles were produced. Influence of inner and outer phases flow rates on particle size, shape, core diameter, shell thickness, and drug release properties was studied. All the particles were monodispersed with coefficient of variation below 5%. Furthermore, their diameter ranged from 100 to 151 μm by increasing continuous (Qc) to middle (Qm) phase flow rate ratio (Qc/Qm). Core diameter varied from 58 to 115 μm by decreasing middle (Qm) to inner (Qi) phase flow rate ratio (Qm/Qi) at constant continuous phase flow rate as confirmed by SEM images. It was observed that an optimum concentration of acrylamide (30 wt%) and an appropriate combination of surfactants were necessary to get core-shell particles otherwise Janus structure was obtained. FTIR confirmed the complete polymerization of core and shell phases. MTT assay showed variation in viability of cells under non-contact and contact conditions with less cytotoxicity for the former. Under non-contact conditions LD50 was 3.1mg/mL. Release studies in USP phosphate buffer solution showed simultaneously release of ketoprofen and ranitidine HCl for non pH-sensitive particles. However, release rates of ranitidine HCl and ketoprofen were higher at low and high pH respectively. To develop pH-sensitive particles for colon targeting, the previous shell phase was admixed with few weight percentage of pH sensitive carboxyethyl acrylate monomer. Core and shell contained the same hydrophobic and hydrophilic model drugs as in previous case. The pH-sensitive shell prevented the release of the two entrapped molecules at low pH while increasing significantly their release rate at higher pH with a maximum discharge at colonic pH of 7.4.

Dye-loaded lipid nano-droplets present an attractive alternative to inorganic nanoparticles, as they are composed of non-toxic biodegradable materials and easy to prepare. However, to achieve high fluorescence brightness, the nano-droplets have to be heavily loaded with the dyes avoiding fluorescence self-quenching and release (leakage) of the encapsulated dyes from the nano-droplets in biological media. In the present work, we have designed highly lipophilic fluorescent derivatives of 3-alkoxyflavone (F888) and Nile Red (NR668) that can be encapsulated in the lipophilic core of stable nano-emulsion droplets at exceptionally high concentrations in the oil core, i.e. up to 170 mM and 17 mM, respectively, corresponding to ~ 830 and 80 dyes per 40-nm droplet. Despite this high loading, these dyes keep high fluorescence quantum yield and thus, provide high nano-droplet brightness, probably due to their bulky structure preventing self-quenching. Moreover, simultaneous encapsulation of both dyes at high concentrations in single nano-droplets allows observation of FRET. FRET and fluorescence correlation spectroscopy (FCS) studies showed that NR668 release in the serum-containing medium is very slow, while the reference hydrophobic dye Nile Red leaks immediately. This drastic difference in the leakage profile between NR668 and Nile Red was confirmed by in vitro cellular studies as well as by in vivo angiography imaging on zebrafish model, where the NR668-loaded nano-droplets remained in the blood circulation, while the parent Nile Red leaked rapidly from the droplets distributing all over the animal body. This study suggests new molecular design strategies for obtaining bright nano-droplets without dye leakage and their use as efficient and stable optical contrast agents in vitro and in vivo.

Polymeric nanoparticles (PNPs) are gaining increasing importance as nanocarriers or contrasting material for preclinical diagnosis by micro-CT scanner. Here, we investigated a straightforward approach to produce a biocompatible, radiopaque, and stable polymer-based nanoparticle contrast agent, which was evaluated on mice. To this end, we used a nanoprecipitation dropping technique to obtain PEGylated PNPs from a preformed iodinated homopolymer, poly(MAOTIB), synthesized by radical polymerization of 2-methacryloyloxyethyl(2,3,5-triiodobenzoate) monomer (MAOTIB). The process developed allows an accurate control of the nanoparticle properties (mean size can range from 140 nm to 200 nm, tuned according to the formulation parameters) along with unprecedented important X-ray attenuation properties (concentration of iodine around 59 mg I/mL) compatible with a follow-up in vivo study. Routine characterizations such as FTIR, DSC, GPC, TGA, 1 H and 13 C NMR, and finally SEM were accomplished to obtain the main properties of the optimal contrast agent. Owing to excellent colloidal stability against physiological conditions evaluated in the presence of fetal bovine serum, the selected PNPs suspension was administered to mice. Monitoring and quantification by micro-CT showed that iodinated PNPs are endowed strong X-ray attenuation capacity toward blood pool and underwent a rapid and passive accumulation in the liver and spleen. Statement of Significance The design of X-ray contrast agents for preclinical imaging is still highly challenging. To date, the best contrast agents reported are based on iodinated lipids or inorganic materials such as gold. In literature, several attempts were undertaken to create polymer-based X-ray contrast agents, but their applicability in vivo was limited to their low contrasting properties. Polymer-based contrast agents present the advantages of an easy surface modification for future application in targeting. Herein, we develop a novel approach to design polymer-based nanoparticle X-ray contrast agent (polymerization of a highly iodine-loaded monomer (MAOTIB)), leading to an iodine concentration of 59 mg/mL. We showed their high efficiency in vivo in mice, in terms of providing a strong signal in blood and then accumulating in the liver and spleen.

A side-by-side capillaries microfluidic device was developed to fabricate drug loaded poly(acrylamide)/poly(methyl acrylate) Janus particles in the range of 59–240 μm by UV-assisted free radical polymerization. This system was characterized in terms of continuous and dispersed phases flow rates (Qc/Qd), monomer composition of the two compartments, surfactant nature and concentration, outlet tube diameter and UV intensity. These factors were adequately controlled to get different particle shapes ranging from core–shell to bi-compartmental particles. For the latter, a low surfactant concentration (0.75 wt.%) was necessary when the two dispersed phases were pumped at equal flow rate, while at high surfactant concentration, dispersed phases flow rates have to be changed. FTIR analysis suggested complete polymerization of monomers and cytotoxicity test showed these particles were biocompatible having LD 50 of 9 mg/mL. Both ketoprofen and sodium fluorescein were released in sustained release manner at pH 6.8 by following a diffusion type release mechanism. Drug release was faster for bigger particles and found to result from the irregular distribution of the two phases and indentation on bigger particles as revealed by SEM analysis. In comparison, sodium fluorescein release was slower which was attributed to low encapsulation but could be modified by decreasing crosslinker concentration.

Chitosan (CS)-based thermosensitive solutions that turn into semi-solid hydrogels upon injection at body temperature have increasingly drawn attention over the last decades as an attractive new type of in situ forming depot (ISFD) drug delivery system. Despite the great potential of the standard CS/β-glycerophosphate (β-GP) thermogelling solutions, their lack of stability over time at room temperature as well as at refrigerated conditions renders them unsuitable as ready-to-use drug product. In the present study, we investigated Glucose-1-Phosphate (G1-P) as an alternative gelling agent for improving the stability of CS-based ISFD solutions. The in vitro release performance of CS/G1-P formulations was assessed using several model compounds. Furthermore, the local tolerance of subcutaneously implanted CS/G1-P hydrogels was investigated by histological examination over three weeks. The thermogelling potential of CS/G1-P solutions, determined by rheology, is dependent on the polymer molecular weight (Mw) and concentration as well as on the G1-P concentration. Differential scanning calorimetry (DSC) measurements confirmed that sol/gel transition takes place at around body temperature and is not fully thermo-reversible. The long term storage stability was evaluated through the appearance, pH, viscosity and gelation time at 37°C of the solution. The results emphasized an enhanced stability of the CS/G1-P system compared to the standard CS/β-GP. CS solution with 0.40 mmol/g G1-P is stable for at least 9 months at 2-8°C, versus less than 1 month when using β-GP as gelling agent. Furthermore, the solution is easy to inject, as evidenced from injectability evaluation using 23-30 G needles. In vitro release experiments showed a sustained release over days to weeks for hydrophilic model compounds, demonstrating thereby that CS/G1-P may be suitable for the prolonged delivery of drugs. The inflammatory reaction observed in the tissue surrounding the hydrogel in rats was a typical foreign body reaction, similar to the one observed for CS/β-GP hydrogels. These features confirm the potential of CS/G1-P solutions as an injectable ready-to-use in situ forming hydrogel.

Inorganic nanomaterials based on heavy elements represent a new class of contrast agents for X-ray computed tomography (CT). Recent advances have shown that these materials are highly suited for CT imaging due to their high density and X-ray absorption capabilities. In this contribution, we demonstrated that tungsten oxide (WO3) nanoparticles coated by poly-ε-caprolactone (PCL) can be used as efficient contrast agent for CT imaging. The obtained particles were characterized by electron microscopy (TEM and SEM), and dynamic light scattering (DLS). We also validated their use for enhanced in vivo imaging, since these nanoparticles were observed to display high X-ray attenuation properties and circulation time (up to 3 h), permitting blood pool imaging.

The current nanotechnology era is marked by the emergence of various magnetic inorganic nanometer-sized colloidal particles. These have been extensively applied and hold an immense potential in biomedical applications including, for example, cancer therapy, drug nanocarriers (NCs), or in targeted delivery systems and diagnosis involving two guided-nanoparticles (NPs) as nanoprobes and contrast agents. Considerable efforts have been devoted to designing iron oxide NPs (IONPs) due to their superparamagnetic (SPM) behavior (SPM IONPs or SPIONs) and their large surface-to-volume area allowing more biocompatibility, stealth, and easy bonding to natural biomolecules thanks to grafted ligands, selective-site moieties, and/or organic and inorganic corona shells. Such nanomagnets with adjustable architecture have been the topic of significant progresses since modular designs enable SPIONs to carry out several functions simultaneously such as local drug delivery with real-time monitoring and imaging of the targeted area. Syntheses of SPIONs and adjustments of their physical and chemical properties have been achieved and paved novel routes for a safe use of those tailored magnetic ferrous nanomaterials. Herein we will emphasis a basic notion about NPs magnetism in order to have a better understanding of SPION assets for biomedical applications, then we mainly focus on magnetite iron oxide owing to its outstanding magnetic properties. The general methods of preparation and typical characteristics of magnetite are reviewed, as well as the major biomedical applications of magnetite.

Thermogelling chitosan (CS)/glycerophosphate (GP) solutions have been reported as a new type of parenteral in situ forming depot system. These free-flowing solutions at ambient temperature turn into semi-solid hydrogels after parenteral administration.Formulation parameters such as CS physico-chemical characteristics, CS/gelling agent ratio or pH of the system, were acknowledged as key parameters affecting the solution stability, the sol/gel transition behavior and/or the final hydrogel structure. We discuss also the use of the standard CS/GP thermogels for various biomedical applications, including drug delivery and tissue engineering. Furthermore, this manuscript reviews the different strategies implemented to improve the hydrogel characteristics such as combination with carrier particles, replacement of GP, addition of a second polymer and chemical modification of CS.The recent advances in the formulation of CS-based thermogelling systems already overcame several challenges faced by the standard CS/GP system. Dispersion of drug-loaded carrier particles into the thermogels allowed achieving prolonged release profiles for low molecular weight drugs; incorporation of an additional polymer enabled to strengthen the network, while the use of chemically modified CS led to enhanced pH sensitivity or biodegradability of the matrix.

Thermo-sensitive gelling systems, like chitosan/polyol-phosphate, are candidates with a high potential for the design of biodegradable drug delivery systems, notably for in situ forming depots. They consist of stable and low viscosity aqueous solutions, liquid at room temperature, which turn into a gel state upon an increase of temperature (e.g., after subcutaneous administration). This technology enables a sustained release of potentially encapsulated active substances. Despite these thermo-gelling solutions being widely studied for the development of parenteral drug delivery systems, most commonly using β-glycerophosphate (β-GP) as gelling agent, the mechanism inducing the gelation and the role of the polyol part in this mechanism has not been clearly elucidated. To investigate the mechanism of the gelation process, comprehensive rheological studies were performed, comparing different chitosan/polyol-phosphate systems varying in the chemical structure of the polyol parts of the gelling agents. As reference, β-GP was compared to glucose-1-phosphate (G1-P) and glucose-6-phosphate (G6-P) and to a polyol-free phosphate salt, Na2HPO4, as well. Frequency sweep experiments at different temperatures or different gelling agent concentrations, temperature, and time sweep tests were performed as complementary experimental approaches. The results disclosed significant trends with widespread implications, establishing a relationship between the chemical structure of the polyol part and the macroscopic gelling behavior of the solutions, that is, transition temperature, gelation time, and gel strength. The new results presented in this study show that increasing the size of the polyol part prevents the interactions between the chitosan chains, strongly influencing the gelling process.

Prolonged periodical variations of the surface density of a film of phospholipids adsorbed on the surface of an air bubble and in contact with a dispersion of phospholipid vesicles (orange) lead to accelerated phospholipid adsorption and lowering of the interfacial tension. The phenomenon is assigned to a coupling between the periodical variation of the surface density of the phospholipid at the interface and its dilute‐to‐condensed (LE‐to‐LC) phase transition.

Microchannels based microfluidic systems are able to obtain monodispersed microparticles but are limited by cost, time and channel clogging. We succeeded in on the fly encapsulation of high ketoprofen contents in acrylate-based copolymer microbeads by environment friendly UV induced free radical polymerization in off-the-shelf co-axial microfluidic device. FTIR shows complete polymerization of acrylate monomers and interaction between carboxylic group of ketoprofen and ester group of monomers. DSC and XRD confirm amorphous nature of drug in microbeads. Different comonomer content formulations show limited drug release at low pH, a helpful properties to avoid gastric irritating effect of ketoprofen associated with conventional dosage forms. At pH 6.8 microbeads release higher content of drug by a non-Fickian diffusion mechanism. Their drug release rate depends upon the weight content of ethyl acrylate in the formulation as well as their size, increasing by increasing the former and decreasing the later.

This study reports a novel one-step synthesis of hybrid iron oxide/polypyrrole multifunctional nanoparticles encapsulating hydrophobic drug and decorated with polyethylene glycol. The overall process is based on the in situ chemical oxidative polymerization of pyrrole along with the reduction of ferric chloride (FeCl3) in the presence of ketoprofen as model drug and PEGylated surfactants. The final product is a nanocomposite composed of polypyrrole and a mixture of FeO/Fe2O3. Different concentrations of ketoprofen were encapsulated in the nanocomposite, and were characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Encapsulation efficiency of the final product was measured by absorption, which can reach up to 98%. The release experiments confirmed complete drug release after about 3h in PBS solution. Morphological characterization of the nanocomposites was performed by electron microscopy (scanning and transmission electron microscopy) which confirmed the spherical geometry and opaque nature of nanoparticles with average particle size well below 50 nm. The final product is multifunctional system, which could act both as a nanocarrier for drug molecules as well as a contrasting agent. Magnetic relaxometry studies confirmed their possible applications as potential contrast agent in the field of magnetic resonance imaging (MRI).

Injection of hyaluronic acid (HA)-based hydrogels has proven to provide many therapeutic benefits. To increase the stability of HA-based products against enzymatic digestion, we modified hyaluronic acid by grafting various amino acids on its carboxylic group and then evaluated the enzymatic stability of the various conjugates in presence of a hyaluronidase. Our results showed that all amino acid-modified HA polymers were more resistant to degradation compared to the native HA albeit with variation according to the amino acids. Amino acids with carboxylate groups such as aspartic acid or with hydroxyl functions (threonine, serine or tyrosine) conferred a particularly strong resistance to HA towards enzymatic digestion. The HA-amino acid products were then cross-linked with butanediol diglycidyl ether (BDDE). The swelling properties of the formed hydrogels appeared close to native HA whereas the increased resistance towards hyaluronidase digestion remained. These results suggest that amino acid-modified HA derivatives can become promising material for viscosupplementation or drug delivery.

ISSN: 1862-832X; International audience; A microplant, starting from monomers to produce polymer particles, is described and integrates polymerization reaction, polymer analysis and nanoparticle formation in a single continuous-flow microprocess. Original contribution is brought by online polymer analysis and inline polymer nanoprecipitation. Multi-detection GPC of samples taken at the outlet of the microreactor actually enables the characterization of linear and branched polymers by combining a concentration- and a mass-sensitive detection technique. When the steady state of the microreactor is reached, micromixer-assisted nanoprecipitation of the polymer solution follows, leading to a colloidal suspension of nanoparticles with a narrow particle size distribution. Particle sizes, around 100?nm, can be tuned by process parameters.

The adsorption dynamics of a series of phospholipids (PLs) at the interface between an aqueous solution or dispersion of the PL and a gas phase containing the nonpolar, nonamphiphilic linear perfluorocarbon perfluorohexane (PFH) was studied by bubble profile analysis tensiometry. The PLs investigated were dioctanoylphosphatidylcholine (DiC(8)-PC), dilaurylphosphatidylcholine, dimyristoylphosphatidylcholine, and dipalmitoylphosphatidylcholine. The gas phase consisted of air or air saturated with PFH. The perfluorocarbon gas was found to have an unexpected, strong effect on both the adsorption rate and the equilibrium interfacial tension (γ(eq)) of the PLs. First, for all of the PLs, and at all concentrations investigated, the γ(eq) values were significantly lower (by up to 10 mN m(-1)) when PFH was present in the gas phase. The efficacy of PFH in decreasing γ(eq) depends on the ability of PLs to form micelles or vesicles in water. For vesicles, it also depends on the gel or fluid state of the membranes. Second, the adsorption rates of all the PLs at the interface (as assessed by the time required for the initial interfacial tension to be reduced by 30%) are significantly accelerated (by up to fivefold) by the presence of PFH for the lower PL concentrations. Both the surface-tension reducing effect and the adsorption rate increasing effect establish that PFH has a strong interaction with the PL monolayer and acts as a cosurfactant at the interface, despite the absence of any amphiphilic character. Fitting the adsorption profiles of DiC(8)-PC at the PFH-saturated air/aqueous solution interface with the modified Frumkin model indicated that the PFH molecule lay horizontally at the interface.

In order to increase the resistance of hyaluronic acid towards enzymatic digestion, we prepared N-alanyl-hyaluronamide derivatives using different amidation methods performed either in water, water/acetonitrile mixture or anhydrous dimethylformamide. Our results indicate that amidation of hyaluronic acid in an anhydrous solvent is effective and led to a degree of substitution of the carboxylic groups up to 100%. We also demonstrated the N-alanyl-hyaluronamides present enhanced resistance towards enzymatic digestion while forming solutions with similar viscosities than solutions of hyaluronic acids of similar lengths.

Hyaluronic acid (HA) is widely used for numerous medical applications, such as viscosupplementation, eye surgery and drug delivery. A broad range of HA-based materials have been developed and described for the enhancement, modulation and control of its therapeutic action, based on chemical modification of polysaccharides. The purpose of this paper is to review the various chemical modification methods and synthetic routes to obtain HA derivatives, encompassing all applications.

Different dextran esters with various degrees of substitution (1, 2 and 3) were synthesized by esterification reaction, with three acid anhydrides: acetic anhydride, propionic anhydride, and butyric anhydride, separately. These modified polysaccharides were characterized by FT-IR, 1H NMR and 13C NMR spectroscopies. Enzymatic degradation of biopolymers by dextranase was also studied. The polymers showing the best degradation profiles were chosen to design blended free films in combination with a polymethacrylate (Eudragit® RS 30D) as a sustained release system for targeting to the colon. These free films were evaluated by permeability of theophylline used as tracer in different in vitro media of the gastro intestinal tract, in presence or in absence of dextranase. From these studies, it was concluded that dextran esters having the lower degree of substitution and constituted of short carbohydrate chains showed the best and significant enzymatic degradation and could be used as a promising carrier for specific colon drug delivery system. Keywords: Colon-Specific Drug Delivery; Polysaccharides; Dextran; Dextranase; Dextran esters; Enzymatic Degradation; Eudragit® RS 30D; Sid-by-side diffusion cell

The undesirable formation of a semi-crystalline phase of dipalmitoylphosphatidylcholine (DPPC) during compression of a monolayer of the phospholipids (mimicking the expiration phase of the respiratory cycle) can be prevented by contacting the monolayer with perfluorooctylethane (C8F17CH2CH3, PFOE). Moreover, the perfluorocarbon (PFC) can dissolve the DPPC liquid-condensed domains that are already formed, and can help re-spread the DPPC molecules at the air/water interface. Criteria are set for the selection of appropriate PFCs. Perfluorooctyl bromide (C8F17Br) and PFOE effectively hinder the adsorption of bovine serum albumin (BSA, solubilized in the sub-phase) upon re-expansion of the DPPC monolayer (inspiration). As a consequence, the PFCs reduce significantly the deleterious delipidating effect of BSA towards the DPPC monolayer. We suggest that combinations of DPPC and a PFC gas may be useful in the treatment of lung conditions, resulting either from a lack of native lung surfactant, such as in the neonate respiratory distress syndrome (NRDS), or from a deterioration of the native lung surfactant function due to plasma proteins, such as in the acute respiratory distress syndrome (ARDS) in adults.

Development of novel anticancer formulations is a priority challenge in biomedicine. However, in vitro models based on monolayer cultures (2D) which are currently used for cytotoxicity tests leave much to be desired. More and more attention is focusing on 3D in vitro systems which can better mimic solid tumors. The aim of the study was to develop a novel one-step highly reproducible technique for multicellular tumor spheroid (MTS) formation using synthetic cyclic RGD-peptides, and to demonstrate availability of the spheroids as 3D in vitro model for antitumor drug testing. Cell self-assembly effect induced by addition of both linear and cyclic RGD-peptides directly to monolayer cultures was studied for 12 cell lines of various origins, including tumor cells (e.i. U-87 MG, MCF-7, M-3, HCT-116) and normal cells, in particular L-929, BNL.CL2, HepG2. Cyclo-RGDfK and its modification with triphenylphosphonium cation (TPP), namely cyclo-RGDfK(TPP) in a range of 10-100μM were found to induce spheroid formation. The obtained spheroids were unimodal with mean sizes in a range of 60-120μm depending on cell line and serum content in culture medium. The spheroids were used as 3D in vitro model, in order to evaluate cytotoxicity effects of antitumor drugs (doxorubicin, curcumin, temozolomide). The developed technique could be proposed as a promising tool for in vitro test of novel antitumor drugs.

Neat fluorocarbons (FCs) are being investigated for pulmonary delivery of drugs and genes, triggering interest on reverse water-in-fluorocarbon emulsions as delivery systems for hydrophilic bioactive materials to the lung. In this paper we examine the ability of a series of perfluoroalkylated amphiphiles with a dimorpholinophosphate polar head group, C n F 2 n +1 (CH 2 ) m OP(O)[N(CH 2 CH 2 ) 2 O] 2 (F n H m DMP, n = 4, 6, 8, 10 and m = 2, 5, 11) to emulsify water in fluorocarbons. F8H11DMP was found to allow the obtaining of both stable water-in-FC emulsions and of microemulsions. For a given formulation (5% (v/v) water, 95% (v/v) perfluorooctyl bromide) stable, narrowly dispersed miniemulsions (mean diameter: 120–150 nm after 1 year at 25 °C) were obtained with F8H11DMP concentrations ranging from 1.5% to 5% (w/v). Molecular diffusion (Ostwald ripening) was determined to be the predominant mechanism of droplet growth in these miniemulsions. For F8H11DMP concentrations higher than 5% (w/v), water-in-FC microemulsions, 12 nm in diameter, were obtained.

Hydroxyflavones in alkaline solutions show high free radical scavenging activities. Quercetin, one of these hydroxyflavones may be submitted to chemical reactions yielding a mixture of mono-, di- and tri-sodium salts. These salts were recovered after solubilization and stepwise precipitation in methylalcohol/ethylacetate solvents. The different salts were analyzed using sodium emission spectrophotometry and nuclear magnetic resonance to determine the number of acid hydrogens at pH 10 and the position of these acid hydrogens. Our study demonstrates that among the three salts of quercetin, the di-sodium compound is endowed with the more efficient scavenging properties in a phosphate buffer at physiological pH 7.4. Physicochemical parameters and free hydroxyl radical scavenging activity relationships were also determined, allowing to explain the mechanisms whereby hydroxyl groups exert their radical scavenging activities.

Surface pressure-area, surface potential-area, and dipole moment-area isotherms were obtained for monolayers made from a partially fluorinated surfactant, (perfluorooctyl)undecyldimorpholinophosphate (F8H11DMP), dipalmitoylphosphatidylcholine (DPPC), and their combinations. Monolayers, spread on a 0.15 M NaCl subphase, were investigated at the air/water interface by the Wilhelmy method, ionizing electrode method, and fluorescence microscopy. Surface potentials were analyzed using the three-layer model proposed by Demchak and Fort. The contribution of the dimorpholinophosphate polar head group of F8H11DMP to the vertical component of the dipole moment was estimated to be 4.99 D. The linear variation of the phase transition pressure as a function of F8H11DMP molar fraction (X(F8H11DMP)) demonstrated that DPPC and F8H11DMP are miscible in the monolayer. This result was confirmed by deviations from the additivity rule observed when plotting the molecular areas and the surface potentials as a function of X(F8H11DMP) over the whole range of surface pressures investigated. Assuming a regular surface mixture, the Joos equation, which was used for the analysis of the collapse pressure of mixed monolayers, allowed calculation of the interaction parameter (xi=-1.3) and the energy of interaction (Delta epsilon =537 Jmol(-1)) between DPPC and F8H11DMP. The miscibility of DPPC and F8H11DMP within the monolayer was also supported by fluorescence microscopy. Examination of the observed flower-like patterns showed that F8H11DMP favors dissolution of the ordered LC phase domains of DPPC, a feature that may be key to the use of phospholipid preparations as lung surfactants.

We have recently reported that water-in-fluorocarbon (FC) reverse emulsions and microemulsions could be used as delivery systems of bioactive materials to the lung, in particular for local administration using pressurized metered-dose inhalers. The surfactant involved in these reverse emulsions is a perfluoroalkylated amphiphile derived from the dimorpholinophosphate polar head group C8F17(CH2)11OP(O)[N(CH2CH2)2O]2 (F8H11DMP). The interaction of F8H11DMP with the lung surfactant is unknown, as well as that of reverse FC microemulsions. In this study, based on film balance measurements and fluorescence microscopy, we report on the mixed monolayer behavior of F8H11DMP and dipalmitoylphosphatidylcholine (DPPC) used as a lung surfactant model at the air/water interface. F8H11DMP/DPPC mixtures formed miscible, liquid expanded (LE) mixed monolayers in the whole range of F8H11DMP molar fractions investigated (XF8H11DMP≥0.33). Repulsive interactions were observed for high surface pressures. Miscible monolayers in LE state were also formed when DPPC/F8H11DMP mixtures were put in contact with perfluorooctyl bromide (PFOB). In this case, however, attractive interactions were observed (for XF8H11DMP=0.33 and 0.5) in the all range of surface pressures investigated. In addition, it was found that spreading a water-in-PFOB microemulsion formulated with F8H11DMP on a DPPC monolayer led to the adsorption of F8H11DMP at the interface and formation of a mixed DPPC/F8H11DMP monolayer.

In this study, we investigated the role of the chemical nature of the oil droplet core of nano-emulsions used as contrast agents for X-ray imaging on their pharmacokinetics and biodistribution. To this end, we formulated PEGylated nano-emulsions with two iodinated oils (i.e., iodinated monoglyceride and iodinated castor oil) and compared them with another iodinated nano-emulsion based on iodinated vitamin E. By using dynamic light scattering and transmission electron microscopy, the three iodinated nano-emulsions were found to exhibit comparable morphologies, size, and surface composition. Furthermore, they were shown to be endowed with very high iodine concentration, which leads to stronger X-ray attenuation properties as compared to the commercial iodinated nano-emulsion Fenestra VC. The three nano-emulsions were i.v. administered in mice and monitored by microcomputed tomography (micro-CT). They showed high contrast enhancement in blood with similar half-life around 6 h but very different accumulation sites. While iodinated monoglycerides exhibited low accumulation in liver and spleen, high accumulation in spleen was observed for iodinated castor oil and in liver for vitamin E. These data clearly highlighted the important role of the oil composition of the nano-emulsion core to obtain strong X-ray contrast enhancement in specific targets such as liver, spleen, or only blood. These differences in biodistribution were partly attributed to differences in the uptake of the nanodroplets by the macrophages in vitro. Another key feature of these nano-emulsions is their long half-elimination time (several weeks), which offers sufficient retention for micro-CT imaging. This work paves the way for the design of nanoparticulate contrast agents for X-ray imaging of selected organs.

In this study, we report on a novel method for the synthesis of poly(acrylamide) Trojan microparticles containing ketoprofen loaded poly(ethyl acrylate) or poly(methyl acrylate) nanoparticles. To develop these composite particles, a polymerizable nanoemulsion was used as a template. This nanoemulsion was obtained in an elongational-flow micromixer (μRMX) which was linked to a capillary-based microfluidic device for its emulsification into micron range droplets. Downstream, the microdroplets were hardened into Trojan particles in the size range of 213–308 μm by UV initiated free radical polymerization. The nanoemulsion size varied from 98 –132 nm upon changes in surfactant concentration and number of operating cycles in μRMX. SEM and confocal microscopy confirmed the Trojan morphology. Under SEM it was observed that the polymerization reduced the size of the nanoemulsion down to 20–32 nm for poly(ethyl acrylate) and 10–15 nm for poly(methyl acrylate) nanoparticles. This shrinkage was confirmed by cryo-TEM studies. We further showed that Trojan microparticles released embedded nanoparticles on contact with suitable media as confirmed by transmission electron microscopy. In a USP phosphate buffer solution of pH 6.8, Trojan microparticles containing poly(ethyl acrylate) nanoparticles released 35% of encapsulated ketoprofen over 24 h. The low release of the drug was attributed to the overall low concentration of nanoparticles and attachment of some of nanoparticles to the poly(acrylamide) matrix. Thus, this novel method has shown possibility to develop Trojan particles convieniently with potential to deliver nanoparticles in the gastrointestinal tract.

Perfluorohexane gas lowers the kinetic barrier that opposes the displacement of albumin by dipalmitoylphosphatidylcholine at the air/water interface submitted to sinusoidal oscillations at frequencies in the range of those encountered in respiration.

Superior brightness of fluorescent nanoparticles places them far ahead of the classical fluorescent dyes in the field of biological imaging. However, for in vivo applications, inorganic nanoparticles, such as quantum dots, are limited due to the lack of biodegradability. Nano-emulsions encapsulating high concentrations of organic dyes are an attractive alternative, but classical fluorescent dyes are inconvenient due to their poor solubility in the oil and their tendency to form non-fluorescent aggregates. This problem was solved here for a cationic cyanine dye (DiI) by substituting its perchlorate counterion for a bulky and hydrophobic tetraphenylborate. This new dye salt, due to its exceptional oil solubility, could be loaded at 8 wt% concentration into nano-droplets of controlled size in the range 30–90 nm. Our 90 nm droplets, which contained >10,000 cyanine molecules, were >100-fold brighter than quantum dots. This extreme brightness allowed, for the first time, single-particle tracking in the blood flow of live zebrafish embryo, revealing both the slow and fast phases of the cardiac cycle. These nano-droplets showed minimal cytotoxicity in cell culture and in the zebrafish embryo. The concept of counterion-based dye loading provides a new effective route to ultra-bright lipid nanoparticles, which enables tracking single particles in live animals, a new dimension of in vivo imaging.

Non-ionic surfactant vesicles (niosomes) are considered as carriers of iobitridol, a diagnostic agent used for X-ray imaging. The niosomes, with a diameter between 150 and 175 nm, are prepared using the film-hydration method followed by sonication. These vesicles were obtained with appropriate mixtures of D-alpha tocopheryl polyethylene glycol 1000 succinate, polyoxyethylene glycol 4000 stearate, sorbitan monostearate, cholesterol and dicetylphosphate. Methods allowing the increase of the rate of encapsulation and the stability of the vesicles were carried out. In addition to the study of the formulation of the vesicles, the physico-chemical and morphological properties of the vesicles have been studied.

When bovine serum albumin (BSA) and dipalmitoylphosphatidylcholine (DPPC) compete for occupation of an air–water interface, the protein rapidly colonizes the interface, effectively hindering the access of the phospholipid, a situation encountered in certain pulmonary conditions. We found that DPPC can totally and irreversibly displace BSA from the surface of a gas bubble when submitted to sustained sinusoidal oscillations at frequencies in the range of those encountered in respiration, and this without recourse to any additive.

Synthesis and formulation of iodinated PCL-mPEG nanocapsules as new original blood pool contrast agents for computed tomography. PCL-mPEG was synthesized and formulated following the emulsion–solvent diffusion process, in the form of iodinated nanocapsules. Physico-chemical characterization of such nano-materials was performed by DLS and transmission electron microscopy. A stability study of the nanocapsules suspension was followed-up to 3 month. Blood biocompatibility was performed. Finally, the nanocapsules suspension radiopacity was evaluated in vitro then in vivo in mice as micro-CT contrast agent. In this study, the iodine concentration in nanocapsules suspension was about 70 mgI/mL. Besides, these nanocarriers appeared non-toxic, and stable in suspension. In vivo, i.v. administration of 10 μL/g of mouse body weight of theses nano-particles induced a vascular contrast enhancement of 168 HU and a half-life in blood of 4.2 +/− 0.5 h. Elimination route of these particles appears mainly performed by the liver, without sequestration in spleen and lymph nodes confirming their stealth properties. This study proposes the first example of iodinated biodegradable polymeric blood pool contrast agent, able to induce an exploitable contrast enhancement. The main advantage of polymeric system compared to lipid ones, lies in their stability and handling, e.g. towards drying for storage.