Conformational Stability Effect of Polymeric Iron Chelators

This work is licensed under a Creative Commons Attribution 4.0 International License.The design and synthesis of metal chelators with extraordinary metal affinities is a basic and challenging scientific problem of both fundamental and practical importance. Here, we demonstrate a “conformational stability effect” that can significantly enhance the metal affinity of ligands after conjugation to polymer chains with the ability to spontaneously adopt a specific conformation as an optimal “soft” scaffold to ensure maximum thermodynamic stability of the metal complexes. Using iron chelators as models, we show that simple conjugation of small molecule catechol ligands to a polyallylamine chain resulted in more than 8–9 orders of magnitude enhancement of the iron-binding affinity, which is comparable to that of enterobactin, the strongest iron chelator ever known. This study demonstrates that flexible polymer chelators may realize the highest possible metal affinities of the conjugated ligands owing to their ability to achieve an optimal conformation, which could advance the identification of strong metal chelators

Calcium condensation of DNA complexed with cell-penetrating peptides offers efficient, noncytotoxic gene delivery

Drug delivery strategies using cell penetrating peptides (CPPs) have been widely explored to improve the intracellular delivery of a large number of cargo molecules. Electrostatic complexation of pDNA using CPPs has been less explored due to the relatively large complexes formed and the low levels of gene expression achieved when using these low molecular weight polycations as DNA condensing agents. Here, condensing nascent CPP polyplexes using CaCl2 produced small and stable nanoparticles leading to gene expression levels higher than observed for control PEI gene vectors. This simple formulation approach showed negligible cytotoxicity in A549 lung epithelial cells and maintained particle size and transfection efficiency even in the presence of serum

Polyarginine Molecular Weight Determines Transfecion Efficiency of Calcium Condensed Complexes

Cell penetrating peptides (CPPs) have been extensively studied in polyelectrolyte complexes as a means to enhance the transfection efficiency of plasmid DNA (pDNA). Increasing the molecular weight of CPPs often enhances gene expression, but poses a risk of increased cytotoxicity and immunogenicity compared to low molecular weight CCPs. Conversely, low molecular weight CPPs typically have low transfection efficiency due to large complex size. Complexes made using low molecular weight CPPs were found to be condensed to a small size by adding calcium. In this study, complexes of low molecular weight polyarginine and pDNA were condensed with calcium. These complexes showed high transfection efficiency and low cytotoxicity in A549 carcinomic human alveolar basal epithelial cells. The relationship between transfection efficiency and polyarginine size (5, 7, 9 or 11 amino acids), polyarginine/pDNA charge ratios, and calcium concentrations were studied. Polyarginine 7 was significantly more effective than other polyarginines under most formulation conditions suggesting a link between cell penetration ability and transfection efficiency

Combination Chemotherapeutic Dry Powder Aerosols via Controlled Nanoparticle Agglomeration

The original publication is available at www.springerlink.comPurpose To develop an aerosol system for efficient local lung delivery of chemotherapeutics where nanotechnology holds tremendous potential for developing more valuable cancer therapies. Concurrently, aerosolized chemotherapy is generating interest as a means to treat certain types of lung cancer more effectively with less systemic exposure to the compound. Methods Nanoparticles of the potent anticancer drug, paclitaxel, were controllably assembled to form low density microparticles directly after preparation of the nanoparticle suspension. The amino acid, L-leucine, was used as a colloid destabilizer to drive the assembly of paclitaxel nanoparticles. A combination chemotherapy aerosol was formed by assembling the paclitaxel nanoparticles in the presence of cisplatin in solution. Results Freeze-dried powders of the combination chemotherapy possessed desirable aerodynamic properties for inhalation. In addition, the dissolution rates of dried nanoparticle agglomerate formulations (~60% to 66% after 8 h) were significantly faster than that of micronized paclitaxel powder as received (~18% after 8 h). Interestingly, the presence of the water soluble cisplatin accelerated the dissolution of paclitaxel. Conclusions Nanoparticle agglomerates of paclitaxel alone or in combination with cisplatin may serve as effective chemotherapeutic dry powder aerosols to enable regional treatment of certain lung cancers

NanoClusters Surface Area Allows Nanoparticle Dissolution with Microparticle Properties

Poorly water soluble drugs comprise the majority of new drug molecules. Nanoparticle agglomerates, called NanoClusters, can increase the dissolution rate of poorly soluble compounds by increasing particle surface area. Budesonide and danazol, two poorly soluble steroids, were studied as model compounds. NanoCluster suspensions were made using a Netzsch MiniCer media mill with samples collected between 5 and 15 hours and lyophilized. DSC and PXRD were used to evaluate the physicochemical properties of the powders and BET was used to determine surface area. SEM confirmed NanoClusters were between 1 and 5 μm. NanoCluster samples showed an increase in dissolution rate compared to the micronized stock and similar to a dried nanoparticle suspension. BET analysis determined an increase in surface area of 8 times for budesonide NanoClusters and 10 to 15 times for danazol NanoClusters compared to micronized stock. Melting temperatures decreased with increased mill time of NanoClusters by DSC. The increased surface area of NanoClusters provides a potential micron-sized alternative to nanoparticles to increase dissolution rate of poorly water soluble drugs

Nanoparticle agglomerates of fluticasone propionate in combination with albuterol sulfate as dry powder aerosols

This is the author's accepted manuscript. Made available by the permission of the publisher.Particle engineering strategies remain at the forefront of aerosol research for localized treatment of lung diseases and represent an alternative for systemic drug therapy. With the hastily growing popularity and complexity of inhalation therapy, there is a rising demand for tailor-made inhalable drug particles capable of affording the most proficient delivery to the lungs and the most advantageous therapeutic outcomes. To address this formulation demand, nanoparticle agglomeration was used to develop aerosols of the asthma therapeutics, fluticasone or albuterol. In addition, a combination aerosol was formed by drying agglomerates of fluticasone nanoparticles in the presence of albuterol in solution. Powders of the single drug nanoparticle agglomerates or of the combined therapeutics possessed desirable aerodynamic properties for inhalation. Powders were efficiently aerosolized (~75% deposition determined by cascade impaction) with high fine particle fraction and rapid dissolution. Nanoparticle agglomeration offers a unique approach to obtain high performance aerosols from combinations of asthma therapeutics

Dynamic Measurements of Membrane Insertion Potential of Synthetic Cell Penetrating Peptide/pDNA/Ca2+ Complexes

This is the published version. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.Noncovalent complexation of plasmid DNA (pDNA) using cell penetrating peptides (CPPs) has been less explored due to the relatively large complex size formed and the low-level gene expression. Here, condensing synthetic CPP polyplexes using CaCl2 produced small and stable complexes, which show higher level of in vitro gene expression. Anionic (i.e., POPS and POPG) or zwitterion (i.e., POPC) phospholipid monolayers at the air-water interface are used as model cell membranes to monitor the membrane insertion potential of synthetic CPPs. The insertion potential of complexes having different cationic (dTAT, H9, K9, R9, and RH9) and amphiphilic (RA9, RL9, and RW9) peptides were recorded using a Langmuir monolayer approach that records complexes adsorption to model membranes. Further, to mimic the pH of early endosome and late endosome and lysosome, phospholipid complex interactions were recorded at normal (pH 7.4) and low (pH 4.4) pH. All the complexes studied induced disruptions in phospholipid packing, which were most pronounced for the complexes having amphiphilic CPPs (i.e., RW9 and RL9). Particularly, the surface pressure of the complexes was significantly lower at normal pH when compared to acidic pH in the presence of POPC and POPS monolayers, except for RL9 and RW9 complexes. In contrast, the surface pressure of the complexes was significantly higher at normal pH when compared to acidic pH in the presence of POPG monolayer. Since the late endosomes contain an abundance of PC lipids and low pH, these results may be highly relevant to understand the efficiency of endosomal escape of these complexes

Leveraging Particle Size and Structure to Control Release of Pharmaceuticals for Human and Animal Health [abstract]

Biomedical Tissue Engineering, Biomaterials, and Medical Devices Poster SessionOrbis Biosciences advances human and animal health pharmaceuticals and vaccines by leveraging controlled release platform technologies. Using Precision Particle Fabrication (PPF) technology, Orbis provides desired delivery rates, including sustained release, pulsatile delivery for single-shot vaccines, and differentiated delivery of novel and generic drugs. By partnering with pharmaceutical companies, Orbis integrates PPF technology into client's products. As a proof point, the team formulated a single injection, 10-day pain relief drug for pets that tightly maintained constant blood levels of the drug. Pharmaceutical and biotech companies do not have a robust, affordable, and scalable solution for controlled release and delivery of drugs. Today's high-cost and low-yield solutions for controlling the size and properties of drug particles have led to: Unpredictable release profiles driven by little control over particle size and morphology; Batch processes that are extremely costly and difficult to scale; and Undesirable toxicity for localized drug delivery. The U.S. market for controlled release is $17BN for human pharmaceuticals and$2.5BN for animal health. Reformulation of an approved drug in a new delivery system is significantly less costly than developing a new drug altogether. This approach optimizes product life cycle by extending patent protection by 10-15 years and recapturing much of the 60-75% drop in revenue attributable to competition from generics. In one example, current postoperative pain medicine options for pets provide relief for only hours at a time. Pet owners have a strong willingness to pay, but available options are inconvenient (repeatable oral doses) or impractical (repeatable visits to the vet). The market calls for a long-acting drug that is safe, convenient, and practical. Using PPF, Orbis has formulated a 10-day pain relief drug for pets to address the U.S. pain relief market. PPF technology produces uniform particles or capsules with a narrow size distribution and precise control over particle morphology (e.g., porosity or coating thickness). This solution provides an affordable, scalable solution for controlled release of active ingredients to: Eliminate the need for multiple administrations and increase patient compliance; Reduce side effects by maintaining a safe, effective drug concentration; Establish greater treatment effectiveness and predictability; Protect active ingredients from interacting with one another or irritating the stomach; and Taste-masking foul-tasting and -smelling ingredients. This development is possible through collaboration of regional organizations including: Public laboratories The University of Kansas Particle Characterization & Formulation Lab works at the interface of medicine and engineering with an emphasis on precisely controlling the physical and chemical properties of particles and biomaterials. PharmCATS, a bioanalytical laboratory affiliated with Kansas State University, provides bioanalytical services and in vivo studies. Private companies Orbis Biosciences, Inc. works with pharmaceutical clients to integrate controlled release technology into products. Beckloff Associates, Inc., advises the team on the clinical path to obtain FDA approval for drugs

Dry powdered aerosols of diatrizoic acid nanoparticle agglomerates as a lung contrast agent

Aerosolized contrast agents may improve the resolution of biomedical imaging modalities and enable more accurate diagnosis of lung diseases. Many iodinated compounds, such as diatrizoic acid, have been shown to be safe and useful for radiographic examination of the airways. Formulations of such compounds must be improved in order to allow imaging of the smallest airways. Here, diatrizoic acid nanoparticle agglomerates were created by assembling nanoparticles into inhalable microparticles that may augment deposition in the lung periphery. Nanoparticle agglomerates were fully characterized and safety was determined in vivo. After dry powder insufflation to rats, no acute alveolar tissue damage was observed 2 h post dose. Diatrizoic acid nanoparticle agglomerates possess the characteristics of an efficient and safe inhalable lung contrast agent