Antigen-loaded pH-sensitive hydrogel microparticles are taken up by dendritic cells with no requirement for targeting antibodies.

Particle-based delivery of encapsulated antigens has great potential for improving vaccine constructs. In this study, we show that antigen-loaded, pH-sensitive hydrogel microparticles are taken up and presented by bone marrow-derived dendritic cells (BMDCs) in vitro and are taken up by dendritic cells (DCs) and monocytes in vivo. This uptake is irrespective of targeting antibodies. BMDCs in vitro and DCs in vivo also display upregulation of activation markers CD80 and CD86 when treated with microparticles, again with no difference in conjugated antibodies, even the agonistic CD40 antibody. We further show that these particles induce enhanced expansion of cytokine-producing CD8 T cells in response to challenge with ovalbumin-expressing vesicular stomatitis virus, in both an accelerated vaccination strategy using pre-loaded BMDCs and a traditional mouse immunization setting.

Triggered rapid degradation of nanoparticles for gene delivery.

Effective gene delivery tools offer the possibility of addressing multiple diseases; current strategies rely on viruses or polyplexes. Encapsulation of DNA within nanoparticles is an attractive alternative method for gene delivery. We investigated the use of our recently developed Logic Gate Nanoparticle for gene delivery. The nanoparticles, composed of a dual pH response random copolymer (poly-ß-aminoester ketal-2), can undergo a two-step "in series" response to endosomal pH. The first sep is a hydrophobic-hydrophilic switch, which is followed immediately by rapid degradation. Rapid fragmentation is known to increase cytoplasmic delivery from nanoparticles. Therefore, we hypothesized that our Logic Gate Nanoparticles would enable increased gene delivery and expression relative to nanoparticles that degrade more slowly such as PLGA-based nanoparticles. Passive nanoparticle entry into cells was demonstrated by delivering Cy5-labeled pDNA encoding EGFP into HCT116, a colon carcinoma cell line. Flow cytometry analysis showed that cells are positive for Cy5-DNA-nanoparticles and produced EGFP expression superior to PLGA nanoparticles. Inhibition of V-ATPases using bafilomycin A1 demonstrates that expression of EGFP is dependent on low endosomal pH. The advanced Logic Gate Nanoparticles offer new therapeutic possibilities in gene delivery and other applications where rapid release is important.

Physical and chemical strategies for therapeutic delivery by using polymeric nanoparticles.

A significant challenge that most therapeutic agents face is their inability to be delivered effectively. Nanotechnology offers a solution to allow for safe, high-dose, specific delivery of pharmaceuticals to the target tissue. Nanoparticles composed of biodegradable polymers can be designed and engineered with various layers of complexity to achieve drug targeting that was unimaginable years ago by offering multiple mechanisms to encapsulate and strategically deliver drugs, proteins, nucleic acids, or vaccines while improving their therapeutic index. Targeting of nanoparticles to diseased tissue and cells assumes two strategies: physical and chemical targeting. Physical targeting is a strategy enabled by nanoparticle fabrication techniques. It includes using size, shape, charge, and stiffness among other parameters to influence tissue accumulation, adhesion, and cell uptake. New methods to measure size, shape, and polydispersity will enable this field to grow and more thorough comparisons to be made. Physical targeting can be more economically viable when certain fabrication techniques are used. Chemical targeting can employ molecular recognition units to decorate the surface of particles or molecular units responsive to diseased environments or remote stimuli. In this review, we describe sophisticated nanoparticles designed for tissue-specific chemical targeting that use conjugation chemistry to attach targeting moieties. Furthermore, we describe chemical targeting using stimuli responsive nanoparticles that can respond to changes in pH, heat, and light.

Inflammation responsive logic gate nanoparticles for the delivery of proteins.

Oxidative stress and reduced pH are important stimuli targets for intracellular delivery and for delivery to diseased tissue. However, there is a dearth of materials able to deliver bioactive agents selectively under these conditions. We employed our recently developed dual response strategy to build a polymeric nanoparticle that degrades upon exposure to two stimuli in tandem. Our polythioether ketal based nanoparticles undergo two chemical transformations; the first is the oxidation of the thioether groups along the polymer backbone of the nanoparticles upon exposure to reactive oxygen species (ROS). This transformation switches the polymeric backbone from hydrophobic to hydrophilic and thus allows, in mildly acidic environments, the rapid acid-catalyzed degradation of the ketal groups also along the polymer backbone. Dynamic light scattering and payload release studies showed full particle degradation only in conditions that combined both oxidative stress and acidity, and these conditions led to higher release of encapsulated protein within 24 h. Nanoparticles in neutral pH and under oxidative conditions showed small molecule release and swelling of otherwise intact nanparticles. Notably, cellular studies show absence of toxicity and efficient uptake of nanoparticles by macrophages followed by cytoplasmic release of ovalbumin. Future work will apply this system to inflammatory diseases.

Multiresponse strategies to modulate burst degradation and release from nanoparticles.

Logic gate nanoparticles, where two chemical transformations take place one after the other, were successfully formulated from a newly synthesized random co-polymer. This polymer, poly([2,2'-(propane-2,2-diylbis(oxy))bis(ethane-2,1-diyl) diacrylate ]-co-[hexane-1,6-diyl diacrylate]-4,4' trimethylene dipiperidine), (poly-ß-aminoester ketal-2) contains two pH responsive moieties within its backbone. As nanoparticles they function akin to an AND logic gate. The ß-aminoester backbone moiety provides a pH triggered solubility switch, only when this switch is "ON" does the ketal moiety also turn "ON" to undergo rapid acid catalyzed hydrolysis. These AND logic gate polymeric nanoparticles were prepared using an oil in water emulsion method. Their degradation in the pH range of 7.4-5 was monitored by dynamic light scattering and showed excellent stability at pH 7.4 and rapid degradation at pH 5. Our results indicate that the prepared logic gate nanoparticles may prove valuable in delivering therapeutics and diagnostics to cells and diseased tissue.

Preparation and evaluation of self-nanoemulsifying tablets of carvedilol.

The purpose of this study was to combine the advantages of self-nanoemulsifying drug delivery systems and tablets as a conventional dosage form emphasizing the excipients' effect on the development of a new dosage form. Systems composed of HCO-40, Transcutol HP, and medium-chain triglyceride were prepared. Essential properties of the prepared systems regarding carvedilol solubility, a model drug, and self-emulsification time were determined. In order to optimize self-nanoemulsifying drug delivery systems (SNEDDS), formulation dispersion-drug precipitation test was performed in the absence and presence of cellulosic polymers. Furthermore, SNEDDS was loaded onto liquisolid powders. P-glycoprotein (P-gp) activity of the selected SNEDDS was tested using HCT-116 cells. Carvedilol showed acceptable solubility in the selected excipients. It also demonstrated improvement in the stability upon dilution with aqueous media in the presence of cellulosic polymers. Use of granulated silicon dioxide improved the physical properties of liquisolid powders containing SNEDDS. It improved the compressibility of the selected powders and the tested SNEDDS showed marked P-gp inhibition activity. Prepared self-nanoemulsifying tablet produced acceptable properties of immediate-release dosage forms and expected to increase the bioavailability of carvedilol.

Evaluation of hybrid liposomes-encapsulated silymarin regarding physical stability and in vivo performance.

Silymarin, a known standardized extract obtained from seeds of Silybum marianum is used in treatment of liver diseases of varying origins. Aiming at improving its poor bioavailability from oral products, silymarin hybrid liposomes are introduced in this work for buccal administration after investigating their stability and in vivo hepatoprotective efficiency. Silymarin loaded hybrid liposomes composed of lecithin (L), cholesterol (Ch), stearyl amine (SA) and Tween 20 (T20) in molar ratio of (9:1:1:0.5) were prepared. Their stability upon storage was studied at 4 degrees C and at ambient conditions. Stored samples were analyzed for percent encapsulation, drug release, particle size, turbidity measurement and visual changes. Characterization of the blend between phospholipid and silymarin was done using FT-IR and DSC which indicated a possible interaction. The stabilized formula of silymarin hybrid liposomes was evaluated upon buccal administration regarding its hepatoprotective activity against carbon tetrachloride-induced oxidative stress in albino rats. The degree of protection was measured using biochemical parameters like serum glutamic oxalacetate transaminase (SGOT) and serum glutamic pyruvate transaminase (SGPT). The introduced silymarin hybrid liposomes produced a significant decrease in both transaminase levels when challenged with CCl(4) (intraperitonially) in comparison with orally administered silymarin suspension. This improvement was also confirmed histopathologically.