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Improved storage stability and immunogenicity of hepatitis B vaccine after spray-freeze drying in presence of sugars

Improved storage stability and immunogenicity of hepatitis B vaccine after spray-freeze drying in presence of sugars

W.F. Tonnis, J.-P. Amorij, M.A. Vreeman, H.W. Frijlink, G.F. Kersten, W.L.J. Hinrichs

Abstract

The current hepatitis B vaccines need to be stored and transported under refrigerated conditions (2–8 °C). This dependence on a cold-chain is highly challenging in areas where hepatitis B virus infections are endemic. To decrease the cold-chain dependency, powder formulations of the hepatitis B surface antigen (HBsAg) without aluminum were prepared by spray-freeze drying in the presence of either inulin or a combination of dextran and trehalose. The stability of HBsAg in the amorphous powder formulations was strongly improved during storage both at room temperature and at an elevated temperature (60 °C), compared to a liquid plain and an aluminum hydroxide adjuvanted HBsAg formulation. Immunogenicity studies in mice showed that reconstituted powder formulations induced higher IgG immune responses after intramuscular administration than those induced after administration of unprocessed plain antigen. Although the immune response was not as high as after administration of aluminum adjuvanted HBsAg, the immune response to the reconstituted vaccines shifted towards a more balanced Th1/Th2 response compared to the aluminum containing HBsAg formulation.

Keywords

Hepatitis B surface antigen; Stabilization; Powder formulation; Inulin; Dextran; Trehalose

Encapsulation of antigen-loaded silica nanoparticles into microparticles for intradermal powder injection

Encapsulation of antigen-loaded silica nanoparticles into microparticles for intradermal powder injection

Yibin Deng, Roman Mathaes, Gerhard Winter, Julia Engert

Abstract

Epidermal powder immunisation (EPI) is being investigated as a promising needle-free delivery methods for vaccination. The objective of this work was to prepare a nanoparticles-in-microparticles (nano-in-micro) system, integrating the advantages of nanoparticles and microparticles into one vaccine delivery system for epidermal powder immunisation. Cationic mesoporous silica nanoparticles (MSNP-NH2) were prepared and loaded with ovalbumin as a model antigen. Loading was driven by electrostatic interactions. Ovalbumin-loaded silica nanoparticles were subsequently formulated into sugar-based microparticles by spray-freeze-drying. The obtained microparticles meet the size requirement for EPI. Confocal microscopy was used to demonstrate that the nanoparticles are homogeneously distributed in the microparticles. Furthermore, the silica nanoparticles in the dry microparticles can be re-dispersed in aqueous solution showing no aggregation. The recovered ovalbumin shows integrity compared to native ovalbumin. The present nano-in-micro system allows (1) nanoparticles to be immobilized and finely distributed in microparticles, (2) microparticle formation and (3) re-dispersion of nanoparticles without subsequent aggregation. The nanoparticles inside microparticles can (1) adsorb proteins to cationic shell/surface voids in spray-dried products without detriment to ovalbumin stability, (2) deliver antigens in nano-sized modes to allow recognition by the immune system.

Keywords

Nanoparticles; Microparticles; Mesoporous silica; Vaccination; Nano-in-microparticle system

Fostering the properties of Zr0.8Sn0.2TiO4 (ZST) ceramics via freeze granulation without sintering additives

Fostering the properties of Zr0.8Sn0.2TiO4 (ZST) ceramics via freeze granulation without sintering additives
S. M. Olhero, Ajay Kaushal and J. M. F. Ferreira

Abstract

The present paper reports the overall benefits of freeze granulation for enhancing the properties of zirconium tin titanate Zr0.8Sn0.2TiO4 (ZST) ceramics in the total absence of sintering additives. The ZST powder was synthesized by solid state reaction and attrition milled in ethanol for 10 h. This starting non-granulated powder (NG-ZST), without and with 1 wt% ZnO as sintering additive, was used to consolidate green bodies by dry pressing. The pure ZST powder was also dispersed in aqueous media to obtain stable suspensions with high solid loadings. Free flowing spherical homogeneous granules were prepared by freeze granulation and used to consolidate ZST green bodies by dry pressing (FG-ZST). The effects of processing variables and sintering temperature (1300–1450 °C) on densification and on the structural, mechanical and electrical properties of ZST ceramics were systematically investigated. Our study clearly reveals the superior properties of FG-ZST ceramics, which derive from an enhanced sintering behaviour associated with the absence of sintering additives.

Spray-Freeze-Drying approach for soluble coffee processing and its effect on quality characteristics

Spray-Freeze-Drying approach for soluble coffee processing and its effect on quality characteristics

S. Padma Ishwarya, C. Anandharamakrishnan

Abstract

The suitability of Spray-Freeze-Drying (SFD) technique for soluble coffee processing was evaluated. The resultant product characteristics were compared against its spray-dried (SD) and freeze-dried (FD) counterparts. SFD and FD coffee powders exhibited a comparable aroma profile as indicated by the electronic nose analysis. SFD resulted in higher volatile retention (93%) than FD (77%) and SD (57%), as inferred from GC–MS analysis. SFD coffee showed instantaneous solubility due to its highly porous nature as observed in morphology studies. SFD coffee depicted monomodal particle size distribution with mean diameter (91.1 μm) ranging between SD (50.41 μm) and FD (636.8 μm) particles. SFD resulted in higher free (ρB, 0.612 g/mL) and tapped (ρT, 0.679 g/mL) bulk densities of the product against SD (ρB: 0.328 g/mL; ρT: 0.388 g/mL) and FD (ρB: 0.345 g/mL; ρT: 0.361 g/mL). SFD coffee exhibited free flowing characteristics as indicated by its Hausner ratio (1.11) and Carr index (10%).

Keywords

Soluble coffee; Spray-Freeze-Drying; Volatile retention; Morphology; Bulk density; Tap density

A study to develop nano-spray freeze dried Co/Ce–La catalyst for the production of hydrogen from bio-renewable feedstock

A study to develop nano-spray freeze dried Co/Ce–La catalyst for the production of hydrogen from bio-renewable feedstock

Dalia R. Abd El-Hafiz, Mohamed A. Ebiad

Abstract

Ultra-fine Ce–Co and Cox/Ce–La (x = 4 and 10%) solid solutions (SS) were prepared for the first time by spray freezing technology, and evaluated in bio-ethanol steam reforming reaction for H2 production. The catalysts were characterized by DLS, XRD, BET and TEM, in order to reveal the structure activity relationship. It was shown that, the addition of La3+ cation to Ce–Co catalyst lead to 100% ethanol conversion at lower reaction temperature (300 °C). Hydrogen selectivity was higher on Ce–Co catalyst than on Cox/Ce–La and increase by increase Co content. Moreover, Cox/Ce–La catalysts provided highest deactivation resistant during 15 h. Characterization of spent catalysts revealed that, the addition of La as a promoter to Ce–Co catalyst preventing sintering at high temperatures. TGA analysis indicates the formation of very small amounts of amorphous carbon on Co10/Ce–La catalyst, while CNT was formed on Ce–Co which responsible for deactivation processes. Both oxygen vacancy and La2O2CO3 acted as carbon scavengers during ESR reaction over Cox/Ce–La.

Keywords

Cobalt; Ceria; Lanthanum; Nano-structures; Spray freeze drying; Hydrogen production

Jet-vortex spray freeze drying for the production of inhalable lyophilisate powders

Jet-vortex spray freeze drying for the production of inhalable lyophilisate powders

Wanning S, Süverkrüp R, Lamprecht A

Abstract

Spray-freeze-dried powders were suggested for nasal, epidermal (needle-free injection) or pulmonary application of proteins, peptides or nucleic acids. In spray-freeze-drying processes an aqueous solution is atomized into a refrigerant medium and subsequently dried by sublimation. Droplet-stream generators produce a fast stream of monodisperse droplets, where droplets are subject to collisions and therefore the initial monodispersity is lost and droplets increase in diameter, which reduces their suitability for pulmonary application. In jet-vortex-freezing, a droplet-stream is injected into a vortex of cold process gas to prevent droplet collisions. Both the injection position of the droplet-stream and the velocity of the cold gas vortex have an impact on the size distributions of the resulting powders. A model solution containing mannitol (1.5%m/V) and maltodextrin (1.5%m/V) was sprayed at 5 droplet-stream positions at distances between 1mm and 30mm from the gas jet nozzle and 5 gas velocities (0.8-6.8m/s) at a process temperature of -100°C. Mean geometric diameters of the highly porous particles (bulk density: 0.012±0.007g/cm3) ranged between 55±4 and 98±4μm. Evaluation of the aerodynamic properties by Next-Generation-Impactor (NGI) analysis showed that all powders had high emitted doses (98±1%) and fine-particle fractions ranged between 4±1% and 21±2%. It was shown that jet-vortex freezing is a suitable method for the reproducible production of lyophilized powders with excellent dispersibility in air, which has a high potential for nasal and pulmonary drug delivery.

KEYWORDS

Droplet collision; Droplet-stream generator; Lyophilization; Porous particles; Protein formulations; Pulmonary drug delivery; Spray freeze drying

Inhalable clarithromycin liposomal dry powders using ultrasonic spray freeze drying

Inhalable clarithromycin liposomal dry powders using ultrasonic spray freeze drying

Tiantian Yea, Jiaqi Yub, Qiuhua Luoa, Shujun Wanga, Hak-Kim Chanb

Abstract

Liposomal dry powder inhalation for the pulmonary administration has a great potential to improve the efficacy of antibiotics while reducing adverse effects. To improve aerosolisation efficiency of liposomal dry powders, we prepared clarithromycin liposomal powder formulations (CLA-Lips-DPIs) by an ultrasonic spray freeze drying (USFD) method using 15% mannitol and 5% sucrose (W:V) as combination lyoprotectants (co-lyoprotectants). The formulation had a porous structure, comprising micron-sized particles with uniform drug content and high drug recovery. Co-lyoprotectants could modulate the liposomal powder from absorbing moisture, resulting in moisture absorption being < 15% (W/W) when stored at 75% relative humility for 2 h. The interaction of CLA, lyoprotectant and lipids of CLA-Lips-DPIs was investigated by differential scanning calorimetry. The reconstituted liposome suspension showed a high entrapment efficiency of up to 80% and a narrow size distribution due to the co-lyoprotectants protection. CLA-Lips-DPIs formulations remained unchanged after 3-month storage at 60% RH and 25 °C with a high aerosol efficiency (emitted dose > 85%, fine particle fraction 43%–50%). These results demonstrated the aerosolisation efficiency and storage of the CLA-Lips-DPIs formulation. Liposomal powder formulations prepared by USFD can potentially be an effective drug delivery system for delivering antibiotics.

Keywords

Ultrasonic spray freeze drying; Liposomes; Clarithromycin; Dry powder inhaler (DPI); Inhalation aerosols; Aerosolisation efficiency

Spray freeze-dried nanofibrillated cellulose aerogels with thermal superinsulating properties

Spray freeze-dried nanofibrillated cellulose aerogels with thermal superinsulating properties

Clara Jiménez-Saelicesa, Bastien Seantiera, Bernard Cathalab, Yves Grohensa

Abstract

Nanofibrillated cellulose (NFC) aerogels were prepared by spray freeze-drying (SFD). Their structural, mechanical and thermal insulation properties were compared to those of NFC aerogels prepared by conventional freeze-drying (CFD). The purpose of this investigation is to develop superinsulating bioaerogels by reducing their pore size. Severe reduction of the aerogel pore size and skeleton architecture were observed by SEM, aerogels prepared by SFD method show a fibril skeleton morphology, which defines a mesoporous structure. BET analyses confirm the appearance of a new organization structure with pores of nanometric sizes. As a consequence, the thermal insulation properties were significantly improved for SFD materials compared to CFD aerogel, reaching values of thermal conductivity as low as 0.018 W/(m K). Moreover, NFC aerogels have a thermal conductivity below that of air in ambient conditions, making them one of the best cellulose based thermal superinsulating material.

Keywords

Nanofibrillated cellulose (NFC); Aerogel; Freeze-drying; Nano structure formation; Thermal superinsulation

A new class of closed-cell aluminium foams reinforced with carbon nanotubes

A new class of closed-cell aluminium foams reinforced with carbon nanotubes

I. Duartea, E. Venturaa, S. Olherob, J.M.F. Ferreirab

Abstract

This manuscript reports on the fabrication of closed-cell aluminium alloy foams reinforced with carbon nanotubes (CNTs) through a novel approach that combines the powder metallurgy method with colloidal processing step that grants uniform dispersion of CNTs into the aqueous suspension of all powder components. Spraying the as prepared suspension into liquid nitrogen followed by lyophilisation enables obtaining homogeneous spherical granules to be used in the powder metallurgy method. Besides ensuring good dispersion of all powder components in the system, the non-agglomerated form of CNTs and the expansion upon foaming foster their structural integrity under stretched conditions in the final foams for an efficient load transfer.

Keywords

reinforced aluminium foams; carbon nanotubes; freeze-granulation; powder metallurgy

Enhancement of oral bioavailability of vitamin E by spray-freeze drying of whey protein microcapsules

Enhancement of oral bioavailability of vitamin E by spray-freeze drying of whey protein microcapsules

Parthasarathi S., C. Anandharamakrishnana

Abstract

Vitamin E microcapsules were effectively prepared using three different techniques: spray drying, freeze-drying and spray freeze-drying with whey protein isolate as an encapsulating agent. The quality of microcapsules was evaluated by particle size distribution, surface morphology, encapsulation efficiency, moisture content, flow properties (Hausner ratio), dissolution properties and in vivo oral bioavailability. Vitamin E microcapsules prepared by spray drying, freeze-drying and spray freeze-drying techniques showed maximum encapsulation efficiencies of 89.6 ± 2.58, 86.1 ± 1.44, and 89.3 ± 2.56 respectively. Both freeze-dried and spray freeze-dried microcapsules showed excellent dissolution behavior with higher ODmax and dissolution rates (k0) than the spray-dried microcapsules due to the presence of numerous porous internal structures. Oral bioavailability study performed in male Wistar rats showed enhanced values of maximum plasma concentration (Cmax) and area under the curve (AUC) for spray freeze-dried microcapsules. The overall results demonstrate that the spray freeze-drying based microencapsulation technique could be a promising strategy to enhance the oral bioavailability of poorly water-soluble bioactive compounds like vitamin E.

Keywords

Vitamin E; Microcapsules; Spray freeze drying; Morphology; Dissolution; Bioavailability