Karl Traina

Study of the morphology of copper hydroxynitrate nanoplatelets obtained by controlled double jet precipitation and urea hydrolysis

A copper hydroxynitrate of stoichiometry Cu2(OH)3NO3, analogous to the layered double hydroxide family, was synthesized by the so-called controlled double jet precipitation technique, and by hydrolysis of urea in the presence of copper nitrate. Special attention has been focused on the size, morphology and agglomeration tendency of the particles. The aim of this work is to define the optimum precipitation conditions in terms of quality and dispersability of the recovered product. Such platelet-like particles can be used as anisotropic fillers in nanocomposite materials. Several reaction parameters such as flow and concentration of the reactant solutions, design of the reactor and addition of a growth modifier were studied. r 2003 Published by Elsevier Science B.V.

New co‐spray‐dried tobramycin nanoparticles–clarithromycin inhaled powder systems for lung infection therapy in cystic fibrosis patients

The aim of the study was to produce easily dispersible and porous agglomerates of tobramycin nanoparticles surrounded by a matrix composed of amorphous clarithromycin. Nanoparticles of tobramycin with a median particle size of about 400 nm were produced by high-pressure homogenisation. The results from the spray-dried powders showed that the presence of these nanoparticles enhanced powder dispersion during inhalation. Moreover, local drug deposition profiles were similar for the two antibiotics, allowing them to reach the target simultaneously. The dissolution-release profiles showed that tobramycin and clarithromycin might dissolve without any difficulties in the lung. The fine particle fraction increased from 35% and 31% for the physical blend for tobramycin and clarithromycin, respectively, to 63% and 62% for the spray-dried formulation containing nanoparticles. These new formulations, showing high lung deposition properties, even at sub-optimal inspiratory flow rates, represent a great possibility for advancing pulmonary drug administration and local therapy of lung infections.

A Modular Approach To Study Protein Adsorption on Surface Modified Hydroxyapatite

Biocompatible inorganic nano- and microcarriers can be suitable candidates for protein delivery. This study demonstrates facile methods of functionalization by using nanoscale linker molecules to change the protein adsorption capacity of hydroxyapatite (HA) powder. The adsorption capacity of bovine serum albumin as a model protein has been studied with respect to the surface modifications. The selected linker molecules (lysine, arginine, and phosphoserine) can influence the adsorption capacity by changing the electrostatic nature of the HA surface. Qualitative and quantitative analyses of linker-molecule interactions with the HA surface have been performed by using NMR spectroscopy, zeta-potential measurements, X-ray photoelectron spectroscopy, and thermogravimetric analyses. Additionally, correlations to theoretical isotherm models have been calculated with respect to Langmuir and Freundlich isotherms. Lysine and arginine increased the protein adsorption, whereas phosphoserine reduced the protein adsorption. The results show that the adsorption capacity can be controlled with different functionalization, depending on the protein-carrier selections under consideration. The scientific knowledge acquired from this study can be applied in various biotechnological applications that involve biomolecule-inorganic material interfaces.

Carrier-free combination for dry powder inhalation of antibiotics in the treatment of lung infections in cystic fibrosis.

The aim of the study was to develop an efficient combination antibiotic formulation containing tobramycin and clarithromycin as a dry powder for inhalation. A carrier-free formulation of the two drugs was produced by spray-drying and characterised for its aerodynamic behaviour by impaction tests with an NGI and release profiles. The particle size distribution, morphological evaluation and crystallinity state were determined by laser diffraction, scanning electron microscopy and powder X-ray diffraction, respectively. Drug deposition profiles were similar for the two antibiotics, which has a synergistic effect, allowing them to reach the target simultaneously at the expected dose. The release profiles show that tobramycin and clarithromycin should probably dissolve without any difficulties in vivo in the lung as 95% of tobramycin and 57% of clarithromycin mass dissolved in 10min for the spray-dried formulation. The FPF increased from 35% and 31% for the physical blend for tobramycin and clarithromycin, respectively, to 65% and 63% for the spray-dried formulation. The spray-dried formulation shows particularly high deposition results, even at sub-optimal inspiratory flow rates, and therefore, represents an attractive alternative in the local treatment of lung infection such as in cystic fibrosis.

Linking flowability and granulometry of lactose powders

The flowing properties of 10 lactose powders commonly used in pharmaceutical industries have been analyzed with three recently improved measurement methods. The first method is based on the heap shape measurement. This straightforward measurement method provides two physical parameters (angle of repose αr and static cohesive index σr) allowing to make a first screening of the powder properties. The second method allows to estimate the rheological properties of a powder by analyzing the powder flow in a rotating drum. This more advanced method gives a large set of physical parameters (flowing angle αf, dynamic cohesive index σf, angle of first avalanche αa and powder aeration %ae) leading to deeper interpretations. The third method is an improvement of the classical bulk and tapped density measurements. In addition to the improvement of the measurement precision, the densification dynamics of the powder bulk submitted to taps is analyzed. The link between the macroscopic physical parameters obtained with these methods and the powder granulometry is analyzed. Moreover, the correlations between the different flowability indexes are discussed. Finally, the link between grain shape and flowability is discussed qualitatively.

Effect of DOPA and dopamine coupling on protein loading of hydroxyapatite

Hydroxyapatite (HA) is a promising carrier material for oral delivery of biomolecules such as proteins and drugs. Ways to increase the loading of such molecules on HA will lead to better nanomedicine. This study reports the surface functionalisation of HA particles using the mussel inspired molecules dopamine (DA) and 3,4-dihydroxy-L-phenylalanine (DOPA), in order to increase protein loading. The adsorption mechanisms are discussed based on the adsorption isotherms, zeta potential, thermal analysis and theoretical models. Results show that DA functionalisation enhanced the loading, while DOPA functionalisation was ineffective.

Protein-calcium phosphate nanocomposites: Benchmarking protein loading via physical and chemical modifications against co-precipitation

The low protein loading capacity of commercially available calcium phosphate (CaP) is a major impediment in effectively using this inorganic material as a protein carrier despite its recognized biocompatibility. In this study, nanocomposites of CaP and BSA were prepared by carefully designed precipitation methods in aqueous media. In the first co-precipitation method (CaP–BSA-1), calcium and phosphate precursors were simultaneously added to the protein solution matrix and in the second method (CaP–BSA-2) the protein solution was added after the reaction of the precursors. The crystallinity and phase composition of the resulting powders were determined using an X-ray diffraction technique. Qualitative confirmation of the presence of BSA on the nanocomposites, was obtained using mass spectrometry, ATR-FTIR and XPS. The results from desorption and thermogravimetric measurements indicated that BSA was trapped inside the cavities in the case of CaP–BSA-1 whereas it was mostly surface adsorbed in the case of CaP–BSA-2. The protein loading capacity of these composites was compared with various physical and chemical surface modification strategies used on commercially available calcium phosphate powders. Nanocomposite particulates were found to have about 275% higher protein loading capacity as compared to a commercial CaP powder with the same surface area. Overall, this study benchmarks the different techniques used for protein loading enhancement on inorganic materials.

Mineralogical and Physical Changes during Sintering of Plastic Red Clays from Sanaga Swampy Valley, Cameroon

The sintering behavior and mechanical properties of four alluvial clays sampled from the Sanaga River (sampling sites: Nanga-Eboko, Mbandjock, Batschenga, and Ebebda), central region of Cameroon were investigated. Specimens were shaped by cold pressing and fired between 850 and 1100°C. X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy were used to monitor microstructural modifications and thermal phase transformations. Linear shrinkage, density, open/closed porosity, and water absorption were used to assess the effects of firing cycle on the mechanical properties of the fired compacts. The results showed that between 850 and 1050°C the mineralogical phases are mainly quartz and feldspar. Mullite, spinel, and cristoballite appear at 1100°C together with viscous phases. The values of apparent density (2.62–2.76 g/cm3), open porosity, and flexural strength (3–30 MPa) of the brown compacts suggest the possible use of these clays for earthenware ceramics such as building bricks, roof and floor tiles.

Effect of freeze-drying and self-ignition process on the microstructural and electrochemical properties of Li{sub 4}Ti{sub 5}O{sub 12}

Graphical abstract: - Highlights: • Li{sub 4}Ti{sub 5}O{sub 12} is prepared by a method involving self-ignition of a freeze-dried gel. • Addition of NH{sub 4}NO{sub 3} modifies the self-ignition propagation mode. • Well-crystallized Li{sub 4}Ti{sub 5}O{sub 12} phase is obtained after only 2 h at 800 °C. • Li{sub 4}Ti{sub 5}O{sub 12} powder has 161 mAh g{sup −1} capacity and good retention at C/4 rate. - Abstract: Crystalline Li{sub 4}Ti{sub 5}O{sub 12} is synthesized by a method involving the freeze-drying and self-ignition of a gel prepared from titanium isopropoxide, lithium nitrate and hydroxypropylmethylcellulose (HPMC). This synthesis route yields crystalline Li{sub 4}Ti{sub 5}O{sub 12} particles after calcination at 800 °C for 2 h. In an alternative route, addition of ammonium nitrate shifts the self-ignition mode from wave-like propagation to simultaneous. Powders with different microstructures are thereby obtained. Electrochemical characterization shows that the best results for Li{sup +} intercalation/desintercalation are obtained for the powder prepared without ammonium nitrate addition. These results highlight the necessity for a control of the self-ignition mode to obtain adequate properties.