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Effect of encapsulation methods on the physicochemical properties and the stability of Lactobacillus plantarum (NCIM 2083) in synbiotic powders and in-vitro digestion conditions

Effect of encapsulation methods on the physicochemical properties and the stability of Lactobacillus plantarum (NCIM 2083) in synbiotic powders and in-vitro digestion conditions

K.S. Yoha, J.A. Moses, C. Anandharamakrishnan

Abstract

Encapsulation of probiotic bacteria requires precise control over a range of process parameters, all of which are technique-specific. The technology of encapsulation has received considerable attention in recent years, owing to the numerous ranges of benefits it offers, particularly in terms of quality retention, storage stability, and targeted delivery. In this research, spray-drying (SD) and spray-freeze-drying (SFD) techniques were used to encapsulate Lactobacillus plantarum (NCIM 2083). Fructo-oligosaccharide (FOS), whey protein (WP) and maltodextrin (MD) were used as encapsulating agents at different formulations. Changes in physicochemical properties were evaluated. FOS:WP:MD (2:0.5:0.5) gave higher encapsulation efficiencies of around 89.21% and 96.16% for SD and SFD, respectively. Probiotic stability was studied under simulated in-vitro digestion conditions and over the storage period of 60 days. SFD synbiotics showed better survivability during digestion; whereas, storage studies indicated around 0.95 fold increased retention of cell viability in SD synbiotics as compared to SFD.

Keywords

Synbiotics, Drying, Encapsulation, Microbial stability, Cell viability

Spray-freezing induced multidimensional morphology tuning of assembled spherical carbon for solar-driven steam generation

Spray-freezing induced multidimensional morphology tuning of assembled spherical carbon for solar-driven steam generation

Da Li, Ang Li, Yaxin Chen, Guanyu Chen, Xiaohong Chen, Dexu Zhang, Haitao Zhu, Imran Ahmed Samo, Huaihe Song

Abstract

Carbon materials have been extensively researched as solar absorbers in the field of solar steam generation (SSG) for their full spectrum absorption, non-biotoxicity, and excellent photothermal properties. In this work, we provide a general ice-templating method for obtaining multidimensional carbon materials controlled by regulating the surface tension during the phase separation of phenolic resin solution. Through spraying the atomized droplets into liquid nitrogen, freeze drying, and carbonization, a type of spherical carbon material assembled with carbon nanosheets with a thickness of about 3 nm can be obtained. With the enhancement of the surface tension by spray and the adjustment of the concentration of phenolic resin, a series of morphologies of carbon materials can be obtained from nanowires to nanosheets and further to spherical assemblies. In addition, an efficient SSG system was designed by combining the carbon material with polyurethane foam as matrix, notably showing good evaporation efficiency of 81.7% with a solar flux of 500 W/m2. This work provides a new idea for the morphology control of assembled carbon materials and has achieved excellent performance in the field of photothermal conversion.

Keywords

Hydroxypropyl beta cyclodextrin: a water-replacement agent or a surfactant upon spray freeze-drying of IgG with enhanced stability and aerosolization

Hydroxypropyl beta cyclodextrin: a water-replacement agent or a surfactant upon spray freeze-drying of IgG with enhanced stability and aerosolization

Shahriar Milani, Homa Faghihi, Abdolhosein Roulholamini Najafabadi, Mohsen Amini, Hamed Montazeri, Alireza Vatanara

Abstract

The great potential of hydroxypropyl beta-cyclodextrin (HPßCD), as a dried-protein stabilizer, has been attributed to various mechanisms namely water-replacement, vitrification and surfactant-like effects. Highlighting the best result in our previous study (weight ratio IgG: HPßCD of 1:0.4), herein we designed to evaluate the efficacy of upper (1:2) and lower (1:0.05) ratios of HPßCD in stabilization and aerosol properties of spray freeze-dried IgG. The protective effect of HPβCD, as measured by size exclusion chromatography (SEC-HPLC) was most pronounced at C3′ and C3″, IgG:trehalose:HPβCD ratios of 1:2:0.25 and 1:2:0.05 with aggregation rate constants of 0.46 ± 0.02 and 0.58 ± 0.01 (1/month), respectively. The secondary conformations were analyzed through Fourier transform infrared spectroscopy (FTIR) and all powders well-preserved with the lack of any visible fragments qualified through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PPAGE). Scanning electron microscopy (SEM) and twin stage impinger (TSI) were employed to characterize the suitability of particles for further inhalation therapy of antibodies and the highest values of fine particle fraction (FPF) were achieved by C3′ and C3″, 56.43 and 48.12%. The powders produced at the current ratio 1:2:0.25 and 1:2:0.05 are superior to our previous examination with regards to manifesting lower aggregation and comparable FPF values.

Application of Spray Freeze Drying to Theophylline-Oxalic Acid Cocrystal Engineering for Inhaled Dry Powder Technology

Application of Spray Freeze Drying to Theophylline-Oxalic Acid Cocrystal Engineering for Inhaled Dry Powder Technology

Ryoma Tanaka, Yusuke Hattori, Makoto Otsuka, Kazuhide Ashizawa

Abstract

Spray freeze drying (SFD) produces suitable particles for the pharmaceutical formulation of dry powders used in dry powder inhalers (DPIs). However, SFD particles have large specific surface area and are partially made up of amorphous solids; this state is hygroscopic and would lead to changes in physicochemical properties by humidity when the particles are stored over the long-term or under high humidity conditions such as in the lungs. This study focused on the application of SFD with a cocrystal technique which can add humidity resistance to the active pharmaceutical ingredients (APIs), and the investigation of the physicochemical properties under high humidity conditions. Cocrystal samples containing theophylline anhydrate (THA) and oxalic acid (OXA) in a molar ratio of 2:1 were prepared by SFD. The crystalline structure, thermal behavior, solid-state, hygroscopicity, stability, and aerodynamic properties were evaluated. Simultaneous in situ measurement by near-infrared and Raman (NIR-Raman) spectroscopy was performed to analyze the humidification process. The SFD sample had a porous particle and an optimal aerodynamic particle size (3.03 μm) although the geometric particle diameter was 7.20 μm. In addition, the sample formed the THAOXA cocrystal with partial coamorphous. The hydration capacity and pseudopolymorphic transformation rate of the SFD sample were much lower than those of THA under conditions of 96.4% relative humidity and 40.0 °C temperature because of the cocrystal formation. The reasons were discussed based on the crystalline structure and energy. The SFD technology for cocrystallization would enable the pharmaceutical preparation of DPI products under environmentally friendly conditions.

Dense and homogeneous MOX fuel pellets manufactured using the freeze granulation route

Dense and homogeneous MOX fuel pellets manufactured using the freeze granulation route

F. La Lumia, L. Ramond, C. Pagnoux, P. Coste

Abstract

MOX fuels (UO2‐PuO2) are used in light water nuclear reactors of several countries and are also potential candidates for fast neutron reactors. Industrial MOX is currently manufactured by a dry‐route process, involving steps with fine powders. To reduce dusting, enhance MOX powder flow properties and decrease manufacturing scrap rate, a new wet‐route process is investigated: the freeze granulation of concentrated water‐based powder suspensions having optimized rheology and dispersion properties. Highly flowable, dustless and easy‐to‐press MOX granules have been elaborated. Sintering green compacts made of such granules gives highly dense and defect‐free pellets which have a very homogeneous U‐Pu spatial distribution, thus improving the fuel characteristics. Indeed, MOX fuels devoid of large Pu‐rich aggregates are thought to have a better behavior under irradiation in reactors by limiting/preventing the formation of the typical high burnup structure.

Rapid freezing using atomized liquid nitrogen spray followed by frozen storage below glass transition temperature for Cordyceps sinensis preservation: Quality attributes and storage stability

Rapid freezing using atomized liquid nitrogen spray followed by frozen storage below glass transition temperature for Cordyceps sinensis preservation: Quality attributes and storage stability

You Tian, Dongmei Li, Wenhuang Luo, Zhiwei Zhu, Wenjia Li, Zhengming Qian, Guangrong Li, Da-Wen Sun

Abstract

Fresh Cordyceps sinensis (CS) is rich in bioactive components but perishable with a short shelf-life and drying is the most common method for its preservation. For better retention of its quality and nutritional values, an innovative preservation technique using rapid freezing based on atomized liquid nitrogen (LN) spray followed by frozen storage below glass transition temperature (Tg) was developed in the current study. Atomized LN spray freezing of CS at −60 °C (LN-60), −80 °C (LN-80) and −100 °C (LN-100) was performed. Freezing rates and quality attributes of CS including electronic conductivity (EC), drip loss (DL), total sugar content (TSC), superoxide dismutase activity (ASOD), basic colour information (L*, a* and b* values) and total colour difference (ΔE) were investigated, and the stability of CS stored at −40 °C, which was below the Tg, for 16 weeks was evaluated. The Tg of CS was determined as −34.86 °C through differential scanning calorimeter (DSC) analysis. Multivariate data analyses including principal component analysis (PCA) and cluster analysis (CA) verified that LN-80 and LN-100 provided CS with better quality indicators, among which, ΔE, DL, and EC were the most predominant ones. The stability test suggested that LN-80 and LN-100 minimized the quality deterioration of CS during the frozen storage.

Keywords

Rapid freezing, Quality preservation, Multivariate data analysis, Principal component analysis, Cluster analysis

Binder Jetting Additive Manufacturing of Ceramics: Comparison of Flowability and Sinterability Between Raw and Granulated Powders

Binder Jetting Additive Manufacturing of Ceramics: Comparison of Flowability and Sinterability Between Raw and Granulated Powders

Wenchao Du, Guanxiong Miao, Lianlian Liu, Zhijian Pei, Chao Ma

Abstract

The objective of this study is to compare three different feedstock powders for the binder jetting process by characterizing their flowability and sinterability. Binder jetting additive manufacturing is a promising technology for fabricating ceramic parts with complex or customized geometries. Granulation is a promising material preparation method due to the potential high sinterability and flowability of the produced powder. However, no study has been made to systematically compare raw and granulated powders in terms of their flowing and sintering behaviors. This paper aims at filling this knowledge gap. Two raw powders (i.e., fine raw powder of 300 nm and coarse raw powder of 70 μm) and one granulated powder from spray freeze drying were compared. Different flowability metrics, including volumetric flow rate, mass flow rate, Hausner ratio, Carr index, and repose angle were measured. Different sinterability metrics, including sintered bulk density, volume shrinkage, and densification ratio were compared for all three powders. Results show that granulated powder achieved comparably high flowability to that of the coarse raw powder and also comparably high sinterability to that of the fine raw powder. Moreover, suitable metrics for the characterization of the sinterability and flowability for these three powders are recommended. This study suggests spray freeze drying produces high-quality feedstock powder for binder jetting process.

Keywords

Additive manufacturing, Binders (Materials), Ceramics, Drying, Feedstock, Flow (Dynamics), Sprays, Density, Materials preparation, Shrinkage (Materials), Sintering

Binder Jetting Additive Manufacturing of Ceramics: Feedstock Powder Preparation by Spray Freeze Granulation

Binder Jetting Additive Manufacturing of Ceramics: Feedstock Powder Preparation by Spray Freeze Granulation

Wenchao Du, Guanxiong Miao, Lianlian Liu, Zhijian Pei

Abstract

Objective of this study is to prepare the binder jetting feedstock powder by spray freeze drying and study the effects of its parameters on the powder properties. Binder jetting additive manufacturing is a promising technology for fabricating ceramic parts with complex or customized geometries. However, this process is limited by the relatively low density of the fabricated parts even after sintering. The main cause comes from the contradicting requirements of the particle size of the feedstock powder: a large particle size (> 5 μm) is required for a high flowability while a small particle size (< 1 μm) for a high sinterability. For the first time, a novel technology for the feedstock material preparation, called spray freeze drying, is investigated to address this contradiction. Using raw alumina nanopowder (100 nm), a full factorial design at two levels for two factors (spraying pressure and slurry feed rate) was formed to study their effects on the properties (i.e., granule size, flowability, and sinterability) of the obtained granulated powder. Results show that high pressure and small feed rate lead to small granule size. Compared with the raw powder, the flowability of the granulated powders was significantly increased, and the high sinterability was also maintained. This study proves that spray freeze granulation is a promising technology for the feedstock powder preparation of binder jetting additive manufacturing.

Inhalable liposomal powder formulations for co-delivery of synergistic ciprofloxacin and colistin against multi-drug resistant gram-negative lung infections

Inhalable liposomal powder formulations for co-delivery of synergistic ciprofloxacin and colistin against multi-drug resistant gram-negative lung infections

Shihui Yu, Shaoning Wang, Peizhi Zou, Guihong Chai, Yu-Wei Lin, Tony Velkov, Jian Li, Weisan Pan, Qi Tony Zhou

Abstract

The aim of this study was to design and characterize dry powder inhaler formulations of ciprofloxacin and colistin co-loaded liposomes prepared by the ultrasonic spray-freeze-drying (USFD) technique. Liposomal formulations and powder production parameters were optimized to achieve optimal characteristics and in-vitro performance such as encapsulation efficiency (EE), particle size, particle distribution index (PDI), fine particle fraction (FPF), emitted dose (ED) and in vitro antibacterial activity. The formulation (F6) with the mannitol (5% w/v) as the internal lyoprotectant and sucrose (5%, w/v), mannitol (10%, w/v) and leucine (5%, w/w) as the external lyoprotectants/aerosolization enhancers showed an optimal rehydrated EE values of ciprofloxacin and colistin (44.9 ± 0.9% and 47.0 ± 0.6%, respectively) as well as satisfactory aerosol performance (FPF: 45.8 ± 2.2% and 43.6 ± 1.6%, respectively; ED: 97.0 ± 0.5% and 95.0 ± 0.6%, respectively). For the blank liposomes, there was almost no inhibitory effect on the cell proliferation in human lung epithelial A549 cells, showing that the lipid materials used in the liposome formulation is safe for use in pulmonary drug delivery. The cytotoxicity study demonstrated that the optimized liposomal formulation (F6) was not cytotoxic at least at the drug concentrations of colistin 5 μg/mL and ciprofloxacin 20 μg/mL. Colistin (2 mg/L) monotherapy showed no antibacterial effect against P. aeruginosa H131300444 and H133880624. Ciprofloxacin (8 mg/L) monotherapy showed moderate bacterial killing for both clinical isolates; however, regrowth was observed in 6 h for P. aeruginosa H133880624. The liposomal formulation displayed superior antibacterial activity against clinical isolates of Pseudomonas aeruginosa H131300444 and P. aeruginosa H133880624 compared to each antibiotic per se. These results demonstrate that the liposomal powder formulation prepared by USFD could potentially be a pulmonary delivery system for antibiotic combination to treat multi-drug resistant Gram-negative lung infections.

Keywords

Ciprofloxacin, Colistin, Liposome, Dry powder inhaler, Ultrasonic spray-freeze-drying, Antimicrobial activity, Aerosol performance

Naked pDNA/hyaluronic acid powder shows excellent long-term storage stability and gene expression in murine lungs

Naked pDNA/hyaluronic acid powder shows excellent long-term storage stability and gene expression in murine lungs

Takaaki Ito, Maino Fukuhara, Tomoyuki Okuda, Hirokazu Okamoto

Abstract

We evaluated the storage stability of powder containing naked plasmid DNA (pDNA) and hyaluronic acid (HA) or mannitol (Man) prepared by the spray-freeze-drying technique, through which we have reported high gene expression without any gene vectors. The powders composed of 5–10-µm porous particles and showing excellent dispersion were stored for 12 months under three storage conditions: 5 °C/Dry, 25 °C/Dry, and 25 °C/75% relative humidity. The humidified powders lost their porous shape within 1 week and were not suitable for inhalation characterization. On the other hand, the powders under dry conditions maintained high inhalation characteristics and pDNA integrity for 12 months. We administered the powders to the lungs of mice. The naked pDNA in HA powder showed significantly higher gene expression compared with that in Man powder and a pDNA-polyethylenimine complex solution. The gene expression of pDNA/HA powder was maintained for 12 months. These results suggest that powder containing naked pDNA is stable on storing under appropriate dry conditions and the naked pDNA/HA powder shows effective pulmonary gene expression.

Keywords

Plasmid DNA, Inhalation, Spray freeze-drying, Pulmonary drug delivery, Lung drug delivery, Gene delivery, Gene therapy