Development of MPC-DPA polymeric nanoparticle systems for inhalation drug delivery applications.

Inhalation of nanoparticles for pulmonary drug delivery offers the potential to harness nanomedicine formulations of emerging therapeutics, such as curcumin, for treatment of lung cancer. Biocompatible nanoparticles composed of poly(2-methacryloyloxyethyl phosphorylcholine)-b-poly(2-(diisopropylamino)ethyl methacrylate) (MPC-DPA) have been shown to be suitable nanocarriers for drugs, whilst N-trimethyl chitosan chloride (TMC) coating of nanoparticles has been reported to further enhance their cellular delivery efficacy; the combination of the two has not been previously investigated. Development of effective systems requires the predictable, controllable, and reproducible ability to prepare nanosystems possessing particle sizes, and drug loading capacities, appropriate for successful airway travel, lung tissue penetration, and tumor suppression. Although a number of MPC-DPA based nanosystems have been described, a complete understanding of parameters controlling nanoparticle formation, size, and morphology has not been reported; in particular the effects of differing solvents phases remains unclear. In this current study a matrix of 31 solvent combinations were examined to provide novel data pertaining to the formation of MPC-DPA nanoparticles, and in doing so afforded the selection of systems with particle sizes appropriate for pulmonary delivery applications to be loaded with curcumin, and coated with TMC. This paper presents the first report of novel data detailing the successful preparation, characterisation, and optimisation of MPC-DPA nanoparticles of circa 150-180nm diameter, with low polydispersity, and a curcumin loading range of circa 2.5-115µM, tunable by preparation parameters, with and without TMC coating, and thus considered suitable candidates for inhalation drug delivery applications.

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone.

OBJECTIVE: Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties. METHODS: Drug release profiles from DPA50 -MPC250 -DPA50 gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM). KEY FINDINGS: DPA50 -MPC250 -DPA50 copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles. CONCLUSIONS: The DPA50 -MPC250 -DPA50 copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone.

Escherichia coli Nissle 1917 enhances bioavailability of serotonin in gut tissues through modulation of synthesis and clearance.

Accumulating evidence shows indigenous gut microbes can interact with the human host through modulation of serotonin (5-HT) signaling. Here we investigate the impact of the probiotic Escherichia coli Nissle 1917 (EcN) on 5-HT signalling in gut tissues. Ex-vivo mouse ileal tissue sections were treated with either EcN or the human gut commensal MG1655, and effects on levels of 5-HT, precursors, and metabolites, were evaluated using amperometry and high performance liquid chromatography with electrochemical detection (HPLC-EC). Exposure of tissue to EcN cells, but not MG1655 cells, was found to increase levels of extra-cellular 5-HT. These effects were not observed when tissues were treated with cell-free supernatant from bacterial cultures. In contrast, when supernatant recovered from untreated ileal tissue was pre-incubated with EcN, the derivative cell-free supernatant was able to elevate 5-HT overflow when used to treat fresh ileal tissue. Measurement of 5-HT precursors and metabolites indicated EcN also increases intracellular 5-HTP and reduces 5-HIAA. The former pointed to modulation of tryptophan hydroxylase-1 to enhance 5-HT synthesis, while the latter indicates an impact on clearance into enterocytes through SERT. Taken together, these findings show EcN is able to enhance 5-HT bioavailability in ileal tissues through interaction with compounds secreted from host tissues.

An adsorbent monolith device to augment the removal of uraemic toxins during haemodialysis.

Adsorbents designed with porosity which allows the removal of protein bound and high molecular weight uraemic toxins may improve the effectiveness of haemodialysis treatment of chronic kidney disease (CKD). A nanoporous activated carbon monolith prototype designed for direct blood contact was first assessed for its capacity to remove albumin bound marker toxins indoxyl sulphate (IS), p-cresyl sulphate (p-CS) and high molecular weight cytokine interleukin-6 in spiked healthy donor studies. Haemodialysis patient blood samples were then used to measure the presence of these markers in pre- and post-dialysis blood and their removal by adsorbent recirculation of post-dialysis blood samples. Nanopores (20-100 nm) were necessary for marker uraemic toxin removal during in vitro studies. Limited removal of IS and p-CS occurred during haemodialysis, whereas almost complete removal occurred following perfusion through the carbon monoliths suggesting a key role for such adsorbent therapies in CKD patient care.

Synthesis and characterization of soybean-based hydrogels with an intrinsic activity on cell differentiation.

The successful regeneration of large defects in traumatized and diseased tissues depends on the availability of biodegradable and bioactive biomaterials able to guide the tissue during its repair by offering both a physical support and a control of its biological mechanisms. Recently, a novel class of natural, biodegradable biomaterials has been obtained by the thermosetting of defatted soy curd. These biomaterials have been shown to regulate the activity of both tissue and inflammatory cells. Here, soybean-based hydrogels with different physicochemical properties and bioactivity have been obtained with a relatively simple and highly reproducible processing method. The content of the different soy components (e.g., the isoflavones) was tuned varying the solvent system during the extraction procedure, while variations in the material crosslinking provided either loose hydrogels or a bioglue. The biomaterials obtained can be used as either bioadhesives or injectable formulations in regenerative medicine as they were shown to stimulate the synthesis of collagen by fibroblasts and the formation of mineralized bone noduli by osteoblasts.

A new class of bioactive and biodegradable soybean-based bone fillers.

The reconstruction of large bone defects in periodontal, maxillofacial, and orthopedic surgery relies on the implantation of biomaterials able to support the growth of new tissue. None of the materials currently available is able to combine all the properties required, which are (i) easy handling, (ii) biodegradation, (iii) low immunogenicity, and more importantly, (iv) induction of tissue regeneration. A new class of biodegradable biomaterials has been obtained by simple thermosetting of defatted soybean curd. The final material can be processed into films, porous scaffolds, and granules for different surgical needs. When incubated in physiological solutions the material shows water uptake of 80%, elongation at break of 0.9 mm/mm, and 25% (w/w) degradation in 7 days. Soybean-based biomaterial granules are shown to reduce the activity of the monocytes/macrophages and of the osteoclasts and to induce osteoblast differentiation in vitro, thus demonstrating a bone regeneration potential suitable for many clinical applications.