News on how Freeze Granulation can improve our powder properties

Mass production of graphene nanoscrolls and their application in high rate performance supercapacitors

Bingna Zheng, Zhen Xu and Chao Gao

The output of graphene nanoscrolls (GNSs) has been greatly enhanced to the gram-level by using an improved spray-freeze-drying method without damaging the high transforming efficiency (>92%). The lowest bulk density of GNS foam reaches 0.10 mg cm⁻³. Due to the unique morphology and high specific surface area (386.4 m² g⁻¹), the specific capacitances of the GNSs (90–100 F g⁻¹ at 1 A g⁻¹) are all superior to those of multiwalled carbon nanotubes meanwhile maintaining excellent rate capabilities (60–80% retention at 50 A g⁻¹). For the first time, all-graphene-based films (AGFs) are fabricated via the intercalation of GNSs into graphene layers. The AGF exhibits a capacitance of 166.8 F g⁻¹ at 1 A g⁻¹ and rate capability (83.9% retention at 50 A g⁻¹) better than those of pure reduced graphene oxide (RGO) films and carbon nanotubes/graphene hybrid films (CGFs).

Graphical abstract: Mass production of graphene nanoscrolls and their application in high rate performance supercapacitors

Production of Inhalation Phage Powders Using Spray Freeze Drying and Spray Drying Techniques for Treatment of Respiratory Infections

Leung SS, Parumasivam T, Gao FG, Carrigy NB, Vehring R, Finlay WH, Morales S, Britton WJ, Kutter E, Chan HK

Abstract

PURPOSE:

The potential of aerosol phage therapy for treating lung infections has been demonstrated in animal models and clinical studies. This work compared the performance of two dry powder formation techniques, spray freeze drying (SFD) and spray drying (SD), in producing inhalable phage powders.

METHOD:

A Pseudomonas podoviridae phage, PEV2, was incorporated into multi-component formulation systems consisting of trehalose, mannitol and L-leucine (F1 = 60:20:20 and F2 = 40:40:20). The phage titer loss after the SFD and SD processes and in vitro aerosol performance of the produced powders were assessed.

RESULTS:

A significant titer loss (~2 log) was noted for droplet generation using an ultrasonic nozzle employed in the SFD method, but the conventional two-fluid nozzle used in the SD method was less destructive for the phage (~0.75 log loss). The phage were more vulnerable during the evaporative drying process (~0.75 log further loss) compared with the freeze drying step, which caused negligible phage loss. In vitro aerosol performance showed that the SFD powders (~80% phage recovery) provided better phage protection than the SD powders (~20% phage recovery) during the aerosolization process. Despite this, higher total lung doses were obtained for the SD formulations (SD-F1 = 13.1 ± 1.7 × 10⁴ pfu and SD-F2 = 11.0 ± 1.4 × 10⁴ pfu) than from their counterpart SFD formulations (SFD-F1 = 8.3 ± 1.8 × 10⁴ pfu and SFD-F2 = 2.1 ± 0.3 × 10⁴ pfu).

CONCLUSION:

Overall, the SD method caused less phage reduction during the powder formation process and the resulted powders achieved better aerosol performance for PEV2.

KEYWORDS:

aerosols; antibiotic-resistant bacteria; phage therapy; pulmonary infections

Solidification of nanosuspensions for the production of solid oral dosage forms and inhalable dry powders

Maria Malamatari, Satyanarayana Somavarapu, Kevin M.G. Taylor & Graham Buckton

Abstract

Introduction: Nanosuspensions combine the advantages of nanotherapeutics (e.g. increased dissolution rate and saturation solubility) with ease of commercialisation. Transformation of nanosuspensions to solid oral and inhalable dosage forms minimises the physical instability associated with their liquid state, enhances patient compliance and enables targeted oral and pulmonary drug delivery.

Areas covered: This review outlines solidification methods for nanosuspensions. It includes spray and freeze drying as the most widely used techniques. Fluidised-bed coating, granulation and pelletisation are also discussed as they yield nanocrystalline formulations with more straightforward downstream processing to tablets or capsules. Spray-freeze drying, aerosol flow reactor and printing of nanosuspensions are also presented as promising alternative solidification techniques. Results regarding the solid state, in vitro dissolution and/or aerosolisation efficiency of the nanocrystalline formulations are given and combined with available in vivo data. Focus is placed on the redispersibility of the solid nanocrystalline formulations, which is a prerequisite for their clinical application.

Expert opinion: A few solidified nanocrystalline products are already on the market and many more are in development. Oral and inhalable nanoparticle formulations are expected to have great potential especially in the areas of personalised medicine and delivery of high drug doses (e.g. antibiotics) to the lungs, respectively.

Keywords

dry powder for inhalation, matrix former, nanosuspension, redispersibility, solidification, solid oral dosage forms, spray-freeze drying

Inhalable nanocomposite microparticles: Preparation, characterization and factors affecting formulation

Elsayed I, AbouGhaly MH

Abstract

INTRODUCTION:

Nanocomposite microparticles are intelligent carriers utilised for pulmonary drug delivery. These carriers are composed of drug-encapsulated nanoparticles dispersed in microstructures of polysaccharides. Upon administration, the inhaled microparticles can penetrate and be deposited deeply in the lung due to their adjusted aerodynamic particle size. Subsequently, the nanoparticles are released into the lung and are retained there for a prolonged time due to their resistance to immunological opsonisation, engulfment and digestion.

AREA COVERED:

Nanocomposite microparticles may be prepared by spray drying, spray freeze drying, spray drying fluidised bed granulation or dry coating techniques. The selection of the included excipients, preparation technique and optimisation of the operational parameter play a significant role in the determination of the aerodynamic particle size, redispersibility of the nanoparticles, morphology, yield, moisture content, flowability and in vitro drug release. Moreover, the in vivo behaviour of this novel carrier may be optimised and traced by studying the lung deposition of the inhaled particles and the biological activity of the encapsulated drug.

EXPERT OPINION:

Nanocomposite microparticles have been found to be superior to both nanoparticles and microparticles and may represent a promising carrier for pulmonary drug delivery.

KEYWORDS:

aerodynamic particle size, lung deposition, nanocomposite microparticles, spray freeze drying.

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Please contact us and we will further discuss the opportunities with Freeze Granulation on your powder system and read more on technology and we propose a Granulation Test of your powder system.

Nanoembedded Microparticles for Stabilization and Delivery of Drug-Loaded Nanoparticles

Bohr A, Water J, Beck-Broichsitter M, Yang M

Abstract

Nanoparticle-based pharmaceutical products are currently finding their way onto the market as a popular strategy to improve the therapeutic efficacy of numerous drugs, hereunder medications for a targeted treatment of severe diseases (e.g., cancer). Drug-loaded polymer and lipid nanoparticles are typically produced via solventbased methods and result in colloidal suspensions, which often suffer from physical and chemical instability (e.g., formation of aggregates) resulting in loss of functionality. There are various ways to stabilize such nanoparticlebased formulations including addition of ionic materials to provide electrostatic repulsion or polymer materials forming a steric barrier between the particles. However, for long-term stability often water needs to be removed to obtain a dry product. For this purpose atomization-based techniques such as spray-drying and spray freeze-drying are frequently used to remove water from the nanoparticle suspensions and to form tailored powder products (e.g., nanoembedded microparticles (NEMs)). NEMs provide an excellent vehicle for both stabilization of nanoparticles and delivery of the nanoparticles to their intended site of action. Excipients such as sugars and biocompatible polymers are used to prepare the surrounding, stabilizing matrix. Further, these “Trojan” vehicles are compatible with a wide range of therapeutic molecules, nanocarriers and applications for different routes of administration. The preparation, properties and stability of these NEMs are described in this review and their application and future development are discussed.

Keywords: Nanoembedded microparticles, drug delivery, spray freeze drying, nanomedicine, nanoparticles, spray drying

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Spark plasma sintering of zirconia/nano-nickel composites

Carlos F. Gutierrez-Gonzalez, Nestor W. Solis Pinargote, Said Agouram,
Pavel Y. Peretyagin, Sonia Lopez-Esteban and Ramon Torrecillas

Abstract

This work describes a whole processing route for obtaining dense and nanostructured zirconia-nickel composites with low contents of metallic phase (1–3.5 vol%). For the processing route, a combinationof spray-freezing and lyophilization has been proposed. After the calcination and reduction of the resultingpowders an X-ray and HRTEM characterization has been performed. This showed the formation of pure zirconia and nickel, well dispersed and homogeneously distributed, nanostructured phases. The obtainedpowders were subsequently sintered by Spark Plasma Sintering (SPS). As a result, dense ZrO2 Ni composites were obtained, revealing that the sizes of the metal particles were kept in the nanometer rangeand appear homogeneously and well dispersed into the ceramic matrix. The mechanical behavior of these materials was evaluated by means of the Vickers hardness, showing and increment of about 25% with respect to pure zirconia with only a Ni concentration of 1 vol%.

Keywords

Spark plasma sintering, nanomaterials, nanocomposites, nanoceramics, powder materials, zirconia-nickel composites, mechanical properties.

Inhalable Spray-Freeze-Dried Powder with L-Leucine that Delivers Particles Independent of Inspiratory Flow Pattern and Inhalation Device

Otake H, Okuda T, Hira D, Kojima H, Shimada Y, Okamoto H

Abstract

PURPOSE:

The purpose of this study was to develop inhalable particles that can reach deep into the lungs efficiently independent of inhalation patterns of patients and inhalation devices. We prepared porous particles including L-leucine (Leu), a dispersive agent, by a spray-freeze-drying (SFD) method and examined the influence of inspiratory flow patterns and inhalation devices with various inhalation resistances.

METHODS:

Four types of SFD powder with different Leu contents (0-10%) were prepared. Scanning electron microscopy and laser diffraction were used to measure the morphology and size distribution of the powders. In-vitro inhalation characteristics were determined using a twin-stage liquid impinger equipped with an inspiratory flow pattern simulator. The effects of Leu on the adhesion force and electrostatic property of the particles were evaluated.

RESULTS:

The inhalation performance of the powders was improved by the addition of Leu. The powders with Leu showed a high inhalation performance regardless of inspiratory flow patterns and devices. The addition of Leu decreased the adhesion force and increased the surface potential of the powders.

CONCLUSIONS:

The SFD particles with Leu showed high inhalation performance regardless of the inhalation patterns and devices, which was attributed to the decreased adhesion force between particles and increased dispersibility.

KEYWORDS:

L-leucine (Leu), dry powder inhaler (DPI), inhalation device, inspiratory flow pattern, spray-freeze-drying (SFD).

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Fabrication and optical studies of transparent Tm, Ho:YAG ceramics

Agata Sidorowicz^,Magdalena Nakielska, Anna Wajler, Helena Węglarz, Katarzyna Jach, Andrzej Olszyna

Abstract

The aim of this work has been to obtain transparent Tm, Ho:YAG ceramics (thulium doping range: 2–6 at.%, holmium doping range: 0.1–1.0 at.%) by reaction sintering using commercial powders. It has been proved that the particle size, purity and degree of agglomeration of the powders used are crucial from the point of view of the optical quality of ceramics. The spectroscopic measurements of Tm, Ho:YAG ceramics with different concentration of active ions (including transmission and emission spectra measurements) have been presented and discussed. As has been found, both concentration of holmium and thulium separately as well as the balance between them are of great importance. Energy transfer between Tm and Ho ions has been demonstrated.

Yttrium aluminum garnet, Transparent ceramic, Tm, Ho:YAG, Freeze Granulation, Reactive sintering.

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Spray Freeze Granulation of Submicron Alumina and its Sintering Behavior via Spark Plasma Sintering

Wei Liu, Zhipeng Xie

Abstract: Spray freeze granulation is an improved method based on spray granulation, solving many limitations of spray granulation. In this work, spray freeze granulation of submicron alumina is performed to explore the possibility of industrial-scale production of dense alumina via spark plasma sintering. Powder pretreatment such as sedimentation and the selection of granules with the appropriate size are employed for the maximum use of the high qualified as-prepared granules and granule sliding, which would provide a guidance for the industrial-scale production. Debound granules were densified via SPS and the corresponding sintering behaviors such as the recorded shrinkage and shrinkage rate were discussed. The comparison of sintering behaviors between granulated and as-received powder are conducted to identify the role of spray freeze granulation in sinterability for dense alumina. The Vickers hardness (Hv) and the fracture toughness (KIC) of the freeze granulated body are higher than the corresponding properties of the as-received body due to the more homogenous microstructure with little agglomeration in the particle packing after freeze granulation.

Keywords: Alumina, Spray freeze granulation, Spark plasma sintering, Sintering behavior.

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Third day at CERAMITEC 2015

Third day at CERAMITEC 2015 on Oct 22th with good discussions upon processing of different powder material by Freeze Granulation and the advantages regarding granule homogeneity and the impact on the ultimate material performance it brings.

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