Spray-dried powder of for control of rice sheath blight disease: Formulation protocol and efficacy testing in laboratory and greenhouse

A spray-dried powder containing Bacillus megaterium was developed and tested for control of rice sheath blight disease in the greenhouse. The formulation consisted of 20 ml of an endospore suspension of B. megaterium, 20% w/v of skim milk powder and 1.25% w/v of polyvinyl pyrrolidone k-90, that were mixed and spray dried at 120 °C. The powder displayed good physical characteristics, such as a low-moisture content and a high solubility in water. Bacterial viability in the powder was 3.5±0.1 × 1011 cfu/g after production and remained relatively stable (at 2.2±0.1 × 1010 cfu/g) after 12 months of storage at room temperature. In the laboratory, a 0.1% (w/v) aqueous solution of the formulation was effective in inhibiting the mycelia growth of Rhizoctonia solani (98.5±0.1% inhibition). Under greenhouse conditions, a 0.1% (w/v) aqueous solution applied by either spraying 1 day before inoculating R. solani or spraying 1, 7 and 15 days after inoculation of rice plants with R. solani was more effective in suppressing sheath blight disease than the blank formulation but was less effective than a chemical fungicide control

Hierarchical structured and programmed vehicles deliver drugs locally to inflamed sites of intestine

Orally administrable drug delivery vehicles are developed to manage incurable inflammatory bowel disease (IBD), however, their therapeutic outcomes are compromised by the side effects of systemic drug exposure. Herein, we use hyaluronic acid functionalized porous silicon nanoparticle to bridge enzyme-responsive hydrogel and pH-responsive polymer, generating a hierarchical structured (nano-in-nano-in-micro) vehicle with programmed properties to fully and sequentially overcome the multiple obstacles for efficiently delivering drugs locally to inflamed sites of intestine. After oral administration, the pH-responsive matrix protects the embedded hybrid nanoparticles containing drug loaded hydrogels against the spatially variable physiological environments of the gastrointestinal tract until they reach the inflamed sites of intestine, preventing premature drug release. The negatively charged hybrid nanoparticles selectively target the inflamed sites of intestine, and gradually release drug in response to the microenvironment of inflamed intestine. Overall, the developed hierarchical structured and programmed vehicles load, protect, transport and release drugs locally to inflamed sites of intestine, contributing to superior therapeutic outcomes. Such strategy could also inspire the development of numerous hierarchical structured vehicles by other porous nanoparticles and stimuli-responsive materials for the local delivery of various drugs to treat plenty of inflammatory gastrointestinal diseases, including IBD, gastrointestinal cancers and viral infections.Peer reviewe

Endocytic uptake, transport and macromolecular interactions of anionic PAMAM dendrimers within lung tissue

Purpose: Polyamidoamine (PAMAM) dendrimers are a promising class of nanocarrier with applications in both small and large molecule drug delivery. Here we report a comprehensive evaluation of the uptake and transport pathways that contribute to the lung disposition of dendrimers. Methods: Anionic PAMAM dendrimers and control dextran probes were applied to an isolated perfused rat lung (IPRL) model and lung epithelial monolayers. Endocytosis pathways were examined in primary alveolar epithelial cultures by confocal microscopy. Molecular interactions of dendrimers with protein and lipid lung fluid components were studied using small angle neutron scattering (SANS). Results: Dendrimers were absorbed across the intact lung via a passive, size-dependent transport pathway at rates slower than dextrans of similar molecular sizes. SANS investigations of concentration-dependent PAMAM transport in the IPRL confirmed no aggregation of PAMAMs with either albumin or dipalmitoylphosphatidylcholine lung lining fluid components. Distinct endocytic compartments were identified within primary alveolar epithelial cells and their functionality in the rapid uptake of fluorescent dendrimers and model macromolecular probes was confirmed by co-localisation studies. Conclusions: PAMAM dendrimers display favourable lung biocompatibility but modest lung to blood absorption kinetics. These data support the investigation of dendrimer-based carriers for controlled-release drug delivery to the deep lung

Hierarchical structured and programmed vehicles deliver drugs locally to inflamed sites of intestine

Orally administrable drug delivery vehicles are developed to manage incurable inflammatory bowel disease (IBD), however, their therapeutic outcomes are compromised by the side effects of systemic drug exposure. Herein, we use hyaluronic acid functionalized porous silicon nanoparticle to bridge enzyme-responsive hydrogel and pH-responsive polymer, generating a hierarchical structured (nano-in-nano-in-micro) vehicle with programmed properties to fully and sequentially overcome the multiple obstacles for efficiently delivering drugs locally to inflamed sites of intestine. After oral administration, the pH-responsive matrix protects the embedded hybrid nanoparticles containing drug loaded hydrogels against the spatially variable physiological environments of the gastrointestinal tract until they reach the inflamed sites of intestine, preventing premature drug release. The negatively charged hybrid nanoparticles selectively target the inflamed sites of intestine, and gradually release drug in response to the microenvironment of inflamed intestine. Overall, the developed hierarchical structured and programmed vehicles load, protect, transport and release drugs locally to inflamed sites of intestine, contributing to superior therapeutic outcomes. Such strategy could also inspire the development of numerous hierarchical structured vehicles by other porous nanoparticles and stimuli-responsive materials for the local delivery of various drugs to treat plenty of inflammatory gastrointestinal diseases, including IBD, gastrointestinal cancers and viral infections.</p

Barriers to Non-Viral Vector-Mediated Gene Delivery in the Nervous System

Efficient methods for cell line transfection are well described, but, for primary neurons, a high-yield method different from those relying on viral vectors is lacking. Viral transfection has several drawbacks, such as the complexity of vector preparation, safety concerns, and the generation of immune and inflammatory responses when used in vivo. However, one of the main problems for the use of non-viral gene vectors for neuronal transfection is their low efficiency when compared with viral vectors. Transgene expression, or siRNA delivery mediated by non-viral vectors, is the result of multiple processes related to cellular membrane crossing, intracellular traffic, and/or nuclear delivery of the genetic material cargo. This review will deal with the barriers that different nanoparticles (cationic lipids, polyethyleneimine, dendrimers and carbon nanotubes) must overcome to efficiently deliver their cargo to central nervous system cells, including internalization into the neurons, interaction with intracellular organelles such as lysosomes, and transport across the nuclear membrane of the neuron in the case of DNA transfection. Furthermore, when used in vivo, the nanoparticles should efficiently cross the blood-brain barrier to reach the target cells in the brain

Dendrimers as anti-inflammatory agents

Dendrimers constitute an intriguing class of macromolecules which find applications in a variety of areas including biology. These hyperbranched macromolecules with tailored backbone and surface groups have been extensively investigated as nanocarriers for gene and drug delivery, by molecular encapsulation or covalent conjugation. Dendrimers have provided an excellent platform to develop multivalent and multifunctional nanoconjugates incorporating a variety of functional groups including drugs which are known to be anti-inflammatory agents. Recently, dendrimers have been shown to possess anti-inflammatory properties themselves. This unexpected and intriguing discovery has provided an additional impetus in designing novel active pharmaceutical agents. In this review, we highlight some of the recent developments in the field of dendrimers as nanoscale anti-inflammatory agents

Dextrin-trypsin and ST-HPMA-trypsin conjugates: Enzyme activity, autolysis and thermal stability

Using monomethoxy poly(ethylene glycol) (mPEG)-trypsin conjugates we recently showed that both PEG molecular weight (1100-5000 g/mol) and linker chemistry affect the rate of protein autolysis and thermal stability. These important factors are often overlooked but they can guide the early choice of optimal polymer/chemistry for synthesis of a lead polymer therapeutic suitable for later formulation development. As we are currently developing dextrin- and semi-telechelic poly[N-(2-hydroxypropyl)methacrylamide] (ST-HPMA)-protein conjugates as new therapeutics, the aim of this study was to examine the effect of polymer on activity, autolysis and its thermal stability using trypsin conjugates as a model and compare to the data obtained for mPEG conjugates. Trypsin conjugates were first synthesized using succinoylated dextrin (Mw ∼ 8000 g/mol, dextrin I; or ∼61,000 g/mol, dextrin II), and a ST-HPMA-COOH (Mw ∼ 10,100 g/mol). The conjugates had a trypsin content of ∼54, 17 and 3 wt% respectively with <5% free protein. When amidase activity (KM, Vmax and Kcat) was determined by using N-benzoyl-l-arginine p-nitroanilide (BAPNA) as substrate, trypsin KM values were not altered by conjugation, but the Vmax was ∼6-7-fold lower, and the substrate turnover rate (Kcat) decreased by ∼5-7-fold. The dextrin II-trypsin conjugate was more stable than the other conjugates and native trypsin at all temperatures between 30 and 70 °C, and also exhibited improved thermal stability in the autolysis assays at 40 °C. © 2009 Elsevier B.V. All rights reserved

Dendrimers: Relationship between structure and biocompatibility in vitro, and preliminary studies on the biodistribution of 125l-labelled polyamidoamine dendrimers in vivo

Dendrimers are highly branched macromolecules of low polydispersity that provide many exciting opportunities for design of novel drug-carriers, gene delivery systems and imaging agents. They hold promise in tissue targeting applications, controlled drug release and moreover, their interesting nanoscopic architecture might allow easier passage across biological barriers by transcytosis. However, from the vast array of structures currently emerging from synthetic chemistry it is essential to design molecules that have real potential for in vivo biological use. Here, polyamidoamine (PAMAM, Starburst™), poly(propyleneimine) with either diaminobutane or diaminoethane as core, and poly(ethylene oxide) (PEO) grafted carbosilane (CSi–PEO) dendrimers were used to study systematically the effect of dendrimer generation and surface functionality on biological properties in vitro. Generally, dendrimers bearing -NH termini displayed concentration- and in 2 the case of PAMAM dendrimers generation-dependent haemolysis, and changes in red cell morphology were observed after 1 h even at low concentrations (10 mg/ml). At concentrations below 1 mg/ml CSi–PEO dendrimers and those dendrimers with carboxylate (COONa) terminal groups were neither haemolytic nor cytotoxic towards a panel of cell lines in vitro. In general, cationic dendrimers were cytotoxic (72 h incubation), displaying IC values 50–300 mg/ml dependent on dendrimer-type, cell-type and generation. Preliminary studies with polyether dendrimers prepared by the convergent route showed that dendrimers with carboxylate and malonate surfaces were not haemolytic at 1 h, but after 24 h, unlike anionic 125 PAMAM dendrimers they were lytic. Cationic I-labelled PAMAM dendrimers (gen 3 and 4) administered intravenously (i.v.) to Wistar rats (|10 mg/ml) were cleared rapidly from the circulation (,2% recovered dose in blood at 1 h). Anionic PAMAM dendrimers (gen 2.5, 3.5 and 5.5) showed longer circulation times (|20–40% recovered dose in blood at 1 h) wit