Endoscopic molecular imaging of early gastric cancer using fluorescently labeled human H-ferritin nanoparticle

Optical imaging technologies improve clinical diagnostic accuracy of early gastric cancer (EGC). However, there was a lack of imaging agents exhibiting molecular specificity for EGCs. Here, we employed the dye labeled human heavy-chain ferritin (HFn) as imaging nanoprobe, which recognizes tumor biomarker transferrin receptor 1 (TfR1), to enable specific EGC imaging using confocal laser endomicroscopy (CLE). TfR1 expression was initially examined in vitro in gastric tumor cells and in vivo through whole-body fluorescence and CLE imaging in tumor-bearing mice. Subsequently, dye labeled HFn was topically applied to resected human tissues for EGC detection. CLE analysis of TfR1-targeted fluorescence imaging allowed distinction of neoplastic from non-neoplastic tissues (P?<?0.0001), and TfR1 expression level was found to correlate with EGC differentiation degrees (P?<?0.0001). Notably, the CLE evaluation correlated well with the immunohistochemical findings (κ-coefficient: 0.8023). Our HFn-nanoprobe-based CLE increases the accuracy of EGC detection and enables visualization of tumor margins and endoscopic resection.     

A Nonionic Polyethylene Oxide (PEO) Surfactant Model: Experimental and Molecular Dynamics Studies of Kolliphor EL

Polyethoxylated, nonionic surfactants are important constituents of many drug formulations, including lipid-based formulations. In an effort to better understand the behavior of formulation excipients at the molecular level, we have developed molecular dynamics (MD) models for the widely used surfactant Kolliphor EL (KOL), a triricinoleate ester of ethoxylated glycerol. In this work, we have developed models based on a single, representative molecular component modeled with 2 force field variations based on the GROMOS 53A6_DBW and 2016H66 force field parameters for polyethoxylate chains. To compare the computational models to experimental measurements, we investigated the phase behavior of KOL using nephelometry, dynamic light scattering, cross-polarized microscopy, small-angle X-ray scattering, and cryogenic transmission electron microscopy. The potential for digestion of KOL was also evaluated using an in vitro digestion experiment. We found that the size and spherical morphology of the KOL colloids at low concentrations was reproduced by the MD models as well as the growing interactions between the aggregates to from rod-like structures at high concentrations. We believe that this model reproduces the phase behavior of KOL relevant to drug absorption and that it can be used in whole formulation simulations to accelerate the formulation development.     

Long-term shelf stability of amphiphilic β-cyclodextrin nanosphere suspensions monitored by dynamic light scattering and cryo-transmission electron microscopy

Amphiphilic β-cyclodextrins (βCDa) were synthesized by statistically grafting hexanoyl carbon chains on the secondary hydroxyl functions of the βCD glucopyranosyl units. The obtained derivative was used to prepare sub-micronic colloidal nanosphere suspensions using a nano-precipitation method. The fresh suspensions contained particles with a diameter ranging from 60–100?nm. Taking into account that the physical stability of colloidal systems remains one of the major problems which can restrict their use in pharmaceutical particulate carrier formulations, the long-term stability of the aqueous nano-dispersions was investigated. Two complementary characterization methods, namely dynamic light scattering and cryo-transmission electron microscopy, were used to control the size distribution and morphology of the nanospheres during storage. The zeta potential was measured as well. An unexpected good physical stability of the suspensions after 3 year storage at room temperature was observed. This behaviour appears to be related to the small size and structural organization of the nanoparticles. The mean diameters determined from light scattering experiments are consistent with those measured from electron micrographs. The slight difference between the values obtained by both methods is discussed.     

Cubosome Dispersions as Delivery Systems for Percutaneous Administration of Indomethacin

Purpose The present study concerns the production and characterization of monooleine (MO) dispersions as drug delivery systems for indomethacin, taken as model anti-inflammatory drug. Methods Dispersions were produced by emulsification and homogenization of MO and poloxamer in water. Morphology and dimensional distribution of the disperse phase have been characterized by cryo-transmission electron microscopy and photon correlation spectroscopy, respectively. X-ray diffraction has been performed to determine the structural organization of the disperse phase. Sedimentation field flow fractionation (SdFFF) has been performed to investigate drug distribution in the dispersion. An in vitro diffusion study was conducted by Franz cell associated to stratum corneum epidermis membrane on cubosome dispersions viscosized by carbomer. In vivo studies based on skin reflectance spectrophotometry and tape stripping were performed to better investigate the performance of cubosome as indomethacin delivery system. Results Microscopy studies showed the coexistence of vesicles and cubosomes. X-ray diffraction revealed the presence of a bicontinuous cubic phase of spatial symmetry Im3m (Q²²⁹). SdFFF demonstrated that no free drug was present in the dispersion. Indomethacin incorporated in viscosized MO dispersions exhibited a lower flux with respect to the analogous formulation containing the free drug in the aqueous phase and to the control formulation based on carbomer gel. Reflectance spectroscopy demonstrated that indomethacin incorporated into MO dispersions can be released in a prolonged fashion. Tape-stripping experiments corroborated this finding. Conclusions MO dispersions can be proposed as nanoparticulate systems able to control the percutaneous absorption of indomethacin.     

A high relaxivity Gd(III)DOTA-DSPE-based liposomal contrast agent for magnetic resonance imaging

The field of molecular imaging aims to visualize and quantify (patho)physiological processes at the cellular and molecular level. Sensitive and site-targeted contrast agents are employed to visualize molecular constituents of processes of interest. The principal aim of this study was to develop a magnetic resonance imaging (MRI) detectable liposome with high relaxivity and stability. To this end, Gd(III)DOTA-DSPE was synthesized and incorporated in a liposomal formulation. The resulting liposomes were extensively characterized in vitro in terms of contrast agent efficiency and structural properties. The liposomes were shown to have a high longitudinal relaxivity, which is crucial for the detection of low concentration molecular markers in molecular imaging studies. We also demonstrated that Gd(III)DOTA-DSPE exhibits no detectable transmetallation upon incubation with Zn(II). This is important as it significantly contributes to the biocompatibility of the contrast agent. The present liposome preparation will serve as versatile and well characterized platform for molecular imaging and targeted drug delivery studies.     

Poly(oligoethylene glycol methacrylate) Star-Shaped Copolymers with Hydroxypropyl Methacrylate Cores

Star-shaped copolymers with crosslinked hyperbranched cores, varying in both number and length of the arms, are prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization technique. Star synthesis is conducted via a simple, “core-first” method. Hydroxypropyl methacrylate monomer is used for the formation of the hyperbranched/crosslinked core, with ethylene glycol dimethacrylate used as a bifunctional monomer in the role of the cross-linker. Two different cross-linker/chain transfer agent ratios are chosen to manipulate the number of the arms in the final star nanostructure. Oligoethylene glycol methacrylate (OEGMA₅₀₀) is used as a biocompatible and hydrophilic component for the creation and extension of the arms. Arm length is controlled by the amount of OEGMA monomer used in the second polymerization step. Molecular characterization of the four synthesized stars is achieved via size exclusion chromatography and nuclear magnetic resonance, which provides information regarding the molar mass, dispersity, and composition of each star-shaped copolymer. Dynamic light scattering (DLS) studies of copolymers in N,N-dimethyl formamide solutions provide sizes of individual copolymer molecules in the size range of 8–20 nm. Aqueous dispersions of copolymers are investigated by DLS, cryogenic transmission electron microscopy, and atomic force microscopy, which show the formation of spherical aggregates with diameters of 60–350 nm, dependent on the arm number and length of star copolymers. The obtained sizes and size distributions, along with the hydroxyl-group-bearing cores, indicate that the star copolymer can be used as potential nanocarriers for drugs or bioimaging agents.     

Confinement of Amorphous Lactose in Pores Formed Upon Co-Spray Drying With Nanoparticles

This study aims at investigating factors influencing humidity-induced recrystallization of amorphous lactose, produced by co-spray drying with particles of cellulose nanocrystals or sodium montmorillonite. In particular, the focus is on how the nanoparticle shape and surface properties influence the nanometer to micrometer length scale nanofiller arrangement in the nanocomposites and how the arrangements influence the mechanisms involved in the inhibition of the amorphous to crystalline transition. The nanocomposites were produced by co-spray drying. Solid-state transformations were analyzed at 60%-94% relative humidity using X-ray powder diffraction, microcalorimetry, and light microscopy. The recrystallization rate constant for the lactose/cellulose nanocrystals and lactose/sodium montmorillonite nanocomposites was lowered at nanofiller contents higher than 60% and was stable for months at 80% nanofiller. The most likely explanation to these results is spontaneous formations of mesoporous particle networks that the lactose is confined upon co-spray drying at high filler content. Compartmentalization and rigidification of the amorphous lactose proved to be less important mechanisms involved in the stabilization of lactose in the nanocomposites.