Characterization of short chain fatty acid microcapsules produced by spray drying

Microcapsules containing short chain fatty acids (SCFA) were produced by spray drying technique using different proportions of gum arabic and maltodextrin as wall materials. Proportions of 5% and 10% of gum arabic and maltodextrin isolated, and a mixture of 5% of maltodextrin and 5% of gum arabic were added to samples of fermented permeate containing SCFA, and spray dried. The microstructure of microcapsules was studied by scanning electron microscopy (SEM) and the size distribution was obtained by laser diffraction. SEM observations showed that the microcapsules structures were affected by type and proportion of wall material tested. Most of the microcapsules containing gum arabic as wall material had surface dents or invaginations. Microcapsules containing maltodextrin were spherical with few surface dents and some of them had pores. The larger microcapsule sizes were observed in those containing maltodextrin. Our results show that microstructure and size of microcapsules are affected by type and proportion of biomaterial used. The samples containing 5% of maltodextrin and the mixture of 5% of gum arabic with 5% of maltodextrin presented smooth surfaces and homogenous size distributions. The corresponding microcapsules are considered optimal to food industrial uses due to the flowability property. Besides, these capsules were found to present a homogenous distribution of diameters, which may give a homogenous flavor distribution to the food products.     

Characterization of biologically active insulin-loaded alginate microparticles prepared by spray drying

Background: Spray drying has been used as a means to encapsulate therapeutics in polymeric matrices to improve stability and alter pharmacokinetics. This research aims to characterize alginate microparticles formed by spray drying to encapsulate insulin for therapeutic delivery applications.

Methods: Particle size was characterized by laser diffraction spectroscopy, morphology by scanning electron microscopy, and protein and polymer distribution by confocal laser scanning microscopy. In addition, particle fines collected from the spray-dryer exhaust unit were characterized for size and morphology. The insulin encapsulation efficiency (EE) was determined after particle dissolution through quantification by spectrophotometric analysis. An in-vitro bioassay involving stimulation of rat L6 myoblasts was developed to confirm the bioactivity of released insulin.

Results: Mean diameter of the product was 2.1?±?0.3 μm. Larger particles appeared spherical, with some smaller particles presenting surface topography variability and divoting. Protein EE was 38.2% ± 9.5%, with confocal microscopy showing the protein and polymer concentrated at the surface of larger particles, but more evenly distributed throughout smaller particles. A bioassay for the in-vitro quantification of insulin bioactivity was developed by calibrating the ratio of phosphorylated to total cellular protein kinase B (PKB; also known as AKT). in insulin-stimulated rat L6 myoblasts. Insulin released from the particles was 88% ± 15% bioactive, showing that spray drying had minimal impact on protein structure.

Conclusion: Spray drying was effective in producing microparticles containing bioactive insulin. Future studies will focus on the improvement of the EE and particle uniformity with the aim of developing this technology further for the encapsulation and delivery of peptide or protein-based therapeutics.     

Synthesis of solid NMC622 particles by spray drying,post-annealing and lithiation

Layered lithium-nickel-manganese-cobalt oxide (NMC) cathode materials are widely used in Li-ion batteries that require high energy densities, such as those used in plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Here we studied the synthesis of NMC622 particles by spray pyrolysis, which is a simple one-step process for production of spherical particles. However, synthesising NMC powder using spray pyrolysis has a tendency to produce hollow NMC particles. To gain insight into the mechanism behind the formation of the hollow particles, one dimensional numerical simulation of the physical and chemical phenomena taking place during spray drying were carried out. The effects of several process parameters, including drying air temperature, drying air mass flow rate, and liquid feed mass flow rate, on the evaporation and particle formation process were studied. The increased evaporation rate at higher temperatures was found to result in crust formation on the droplet surface during the particle formation, and thus, in lower solid volume fractions in the dried particles. However, by optimizing the process parameters production of solid NMC622 sulphate particles by spray drying was achieved. The produced NMC622 sulphate particles were then oxidised and lithiated in air at 850 °C via the conventional thermal treatment process. Four lithium precursors, LiOH, Li₂CO₃, Li₂SO₄ and LiNO_3, were tested for the lithiation of the oxidized NMC particles. The degree of lithiation and the crystalline phase of the powders were determined using ICP-OES and XRD, respectively.     

High-yield spray drying assembly and reactive properties of nanoenergetic mesoparticle composites

Electrospray has been demonstrated to assemble fuel and oxidizer nanoparticles with a gas-generating binder into microscale particle composites. This approach results in reactivity enhancement of nanothermite systems by alleviating reactive sintering of the nanoparticle components due to rapid gasification. However, this method is not readily scalable and amenable to large-scale manufacturing due to its slow solution processing rates and the risks associated with the presence of high electric fields in the presence of electrostatic discharge-sensitive reactive materials. Here, we explore spray drying as an alternative approach to assemble Al/CuO nanoparticles into nitrocellulose (NC)-based mesoparticle composites and evaluate their energetic performance against physically mixed powders and electrosprayed mesoparticles. The spray dried mesoparticles show ∼2–7-fold higher pressurization rates and shorter burn times than their physically mixed counterparts and follow a similar trend with electrospray. The higher reactivity of the mesoparticles is attributed to rapid gas generation and reduced sintering from the decomposition of the NC binder. We further demonstrate that spray drying generates mesoparticles with size (∼1.5–4 μm), morphology, and reactivity enhancement similar to that from the electrospray method, while achieving remarkably high production rates (as high as ∼275 g h⁻¹). Thus, this work presents spray drying as a highly scalable strategy to achieve reactivity enhancement and processability, thereby enabling high-yield manufacturing of energetic materials, which is a prelude to what might evolve into 3-D printing approaches for propellants.     

Optimized particle engineering of fluticasone propionate and salmeterol xinafoate by spray drying technique for dry powder inhalation

Asthma is one of the most common respiratory diseases that can be efficiently managed through combined treatment of fluticasone propionate (FP) and salmeterol xinafoate (SX). In this study, we challenged the use of both spray drying and mixing techniques in sequential combination of lactose or mannitol with FP and SX as two steps in development of inhalable powder formulation of the drugs. Leucine was used as a dispersibility enhancer. The formulations were optimized using the Design-Expert software. The effects of three independent variables namely the type of carrier, percentage of spray-dried carrier and the amount of leucine were investigated on in vitro deposition. The results showed that the maximum fine particle fraction (FPF) and the minimum particle size was belonged to formulation in which the percentage of leucine was 20% with respect to the total solid content and 50% of mannitol was used during spray drying, while the remaining 50% of it was applied in the physical mixing process. This study showed that not only the choice of carrier and additives for every drug combination, but also an optimized ratios of them during both spray drying and physical mixing can be crucial in developing suitable inhalable dry powder formulations.     

Co-processing of cefuroxime axetil by spray drying technique for improving compressibility and flow property

The aim of the present investigation was to improve the compressibility and flow property of cefuroxime axetil by co-processing it with mannitol and chitosan chlorhydrate using spray drying method. 3² full factorial design, having inlet air temperature and mannitol: chitosan chlorhydrate ratio as independent variables was used for the optimization. Statistical analysis of obtained results revealed that both independent variables had significant effect on response variables (p value?<?.05). Evaluation of dependent variables suggested, excellent to good flow properties (angle of repose, Carr's index, and Hausner's ratio) for all prepared batches. Desirability function was used for the selection of the optimized batch which was evaluated for Kawakita’s equation, Heckel’s plot to assess compression behavior of co-processed product under applied pressure. Result of this analysis revealed that the optimized batch product had better compressibility than physical mixture. The tablets prepared by directly compressing spray-dried product, exhibited excellent tensile strength acceptable friability (<1%) and similar release profile when compared with marketed formulation (Similarity factor 89.24 and dissimilarity factor 1.79). So the results of the present investigation concluded that cefuroxime axetil was successfully co-processed with above mentioned excipients by using spray drying method to make it directly compressible.     

聚乳酸/聚己内酯共混膜的制备及其性能

为综合聚乳酸(PLA)和聚己内酯(PCL)的性能,将PLA和PCL原料进行熔融共混挤出造粒,再利用溶液浇铸的方法制备不同比例的PLA/PCL共混膜,并对其性能进行一系列的表征和讨论.研究结果表明,PLA与PCL可以以一定比例共混并浇铸成膜.共混膜的红外光谱中没有出现新的特征峰,说明两者共混过程中没有发生化学反应.共混膜的DSC曲线及扫描电镜图表明,PLA与PCL是不相容体系.接触角测试表明,共混膜具有比纯PLA膜和纯PCL膜更好的水润湿性.力学性能测试表明,PLA/PCL共混膜可以克服单一材料力学性能上的缺陷.     

Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and microhardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO₂. Flexural strength and fracture toughness were dependent on CeO₂ concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce-ZrO₂ with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness, 9.2 MPa√m.     

Utilizing spray drying technique to improve oral bioavailability of apigenin

The aim of this study was to prepare, characterize, and evaluate apigenin in a solid dispersion system to improve the dissolution rate and bioavailability of such poorly soluble drug. Apigenin was dissolved in organic solvent with micelle forming polymer Pluronic F-127 (PL-F127). Solid dispersion of apigenin-PL F-127 was developed using spray drying technique. Physicochemical and in vitro characterization of the produced solid dispersion particles were conducted using scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, powder X-ray diffractometry and dissolution study. In addition, in vivo study was performed for the spray dried versus pure and marketed apigenin. C_max was found to be around 5 folds higher for spray dried product compared to non spray dried materials. The prepared drug:polymer formulation showed elongated particles and complete lack of crystallinity at 1:4 ratio. The change in the vibrational wave numbers strongly suggested the formation of hydrogen bonding between apigenin and PL F-127. Significant increase in the dissolution rate and bioavailability of the spray dried apigenin showed the potential of solid dispersion system to overcome problem related to BCS II drugs.     

聚乳酸/木粉复合材料的力学及吸水性能研究

采用聚乳酸（PLA）及偶联剂马来酸酐（MAPP）对木粉进行改性,研究采用熔融共混方法制备的聚乳酸/木粉复合材料的力学性能、吸水性能、微观特性,以及宏观与微观之间的联系。研究结果表明力学性能方面,随着木粉含量从10g增加到25g,最大拉力增加了4倍,抗拉强度增加了3倍;偶联剂使用后,最大拉力和抗拉强度较未使用前最大增加值都超过了1倍。吸水性能方面,随着木材成分的增加,复合材料的吸水率同时增加,2和24h增重最多分别为2.85%和8.12%;偶联剂的使用降低了复合材料的吸水率,2和24h增重最多分别为0.72%和3.58%。最后使用电子扫描显微镜（SEM）观察发现同样木粉含量,添加偶联剂后界面更加光滑,PLA与木粉之间的粘合更紧密。     

CFD-aided population balance modeling of a spray drying process

Due to the widespread application of spray dryers, the model-based optimization and control of the process are of great interest. Therefore, a reduced order model based on a population balance approach for the spray drying process is developed to accurately capture the shrinkage and drying mechanisms. The population balances describe the two-dimensional distribution of the moisture content and the granule size. The model is validated by experiments in a pilot scale spray dryer. Information from CFD simulations and previous single droplet experiments are used to determine suitable model parameters. The results show a good agreement of the model with experimental findings and promote the suitability of the population balance approach. Furthermore, a novel method of extracting information on the trajectories from detailed CFD simulations and inserting them into the reduced order model is presented. This increases the accuracy of the model without changing the computational complexity.     

Preparation of drug nanocrystals embedded in mannitol microcrystals via liquid antisolvent precipitation followed by immediate (on-line) spray drying

The aim of this study is to investigate the feasibility of producing pharmaceutical nanoformulations for enhanced oral or pulmonary delivery of poorly water-soluble drugs via liquid antisolvent precipitation followed by immediate (on-line) spray drying. A poorly water-soluble corticosteroid, budesonide, was chosen as the model drug. Budesonide nanoparticles were prepared through liquid antisolvent precipitation, and then processed into a powdered nanoformulation which consists of budesonide nanoparticles embedded in mannitol microcrystals by immediate (on-line) spray drying. The size of the freshly precipitated and the reconstituted budesonide particles was analyzed by dynamic light scattering (DLS). The spray-dried nanoformulation, together with budesonide and mannitol raw materials, their physical mixture and the spray-dried mannitol, were characterized by field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). In vitro dissolution test and aerosol deposition study were conducted on the spray-dried nanoformulation and the physical mixture of budesonide and mannitol raw materials. It was found that the spray-dried nanoformulation, consisting of mannitol microcrystals comprising budesonide nanocrystals with z-average mean size of 520?±?11.4?nm, exhibited enhanced drug dissolution rate and higher fine particle fraction (FPF). The results of this study indicated the potential of the combined process of liquid antisolvent precipitation followed by immediate (on-line) spray drying to be used as a direct and continuous formulation process to produce powdered nanoformulations to achieve enhanced oral or pulmonary delivery of poorly water-soluble drugs.     

Manufacture of a hydrophobic CaO/polylactic acid composite

In this study, the surface of calcium oxide (CaO) was modified with n-octadecyltrichlorosilane [CH₃(CH₂)₁₆CH₂SiCl₃] to obtain modified calcium oxide (CaO-M). CaO and CaO-M were melt-blended with polylactic acid (PLA) to prepare PLA/CaO and PLA/CaO-M, respectively. Moisture absorption measurement showed that the surface of modified CaO was changed from hydrophilic to hydrophobic. CaO and PLA had a tendency to agglomerate after blending, whereas the blend of CaO-M and PLA showed no signs of agglomeration, and the distribution of CaO-M in PLA was homogeneous. In addition, CaO-M had a heterogeneous nucleation effect on PLA, which effectively inhibited cold crystallization and promoted crystallization of PLA. In conclusion, CaO-M can be used as a nucleating agent of PLA.     

Structural and electrical properties of the Y-Ba-Cu-O superconducting films prepared by spray pyrolysis

High-T _c , superconducting YBa₂Cu₃O_7– thin films have been grown on (100) MgO substrates by a chemical spray pyrolysis method. The crystal structure and surface morphology have been studied by X-ray diffraction and scanning electron microscopy, respectively. The assprayed films were amorphous and insulating, but upon annealing the films became superconducting and show a textured surface morphology with an average grain size of the order of 5–15m. The films were highly oriented with thec-axis being perpendicular to the substrate surface. Three different microstructures were recorded: long rod-shaped grains, platelet or rounded-shape grains, and a melting-like growth. Electrical measurements were carried out in a low-temperature cryostat using a standard d.c. four-probe technique. The onset transition temperature was around 83–86 K, and the completion of the transition to zero resistance was in the range 73–78 K. The magnitude of the measured critical current density was in the range 750–3750 A/cm² at 30 K. A correlation between the resistance of the tunnelling junctions and the critical current density was found from the theoretical models.     

Production of stable amorphous form by means of spray drying

Spray drying is a very useful method for manufacturing of amorphous solid materials. This is mainly due to the possibility of fast solvent evaporation that leads to a rapid transformation of solution to a solid state. Besides evaporation kinetics, there are various process parameters that influence physical and chemical characteristics of such obtained material. The possibility of obtaining a stable amorphous structure of the active pharmaceutical ingredient in a spray dryer was examined. A solution of the hydrochloride crystalline structure of the active pharmaceutical ingredient in a mixture of water and acetonitrile was dried at different temperatures and flowrates of nitrogen used for atomization, as well as the flowrates of the solution. The influence of the process conditions on the properties of the product was analyzed. The final dried products were characterized and identified with a variety of analytical and physical methods. The results showed that a stable amorphous structure of the high purity active pharmaceutical ingredient is obtained, and that the optimal conditions of the process are defined. The amorphous structure is stable at temperatures below 200°C when it is transformed into a new crystal structure. Conditions of high relative air humidity lead to partial transformation.     

生物可降解高分子增韧聚乳酸的研究进展

聚乳酸(PLA)是一种新型的生物基可再生生物降解材料,因具有高机械强度、易加工性、高熔点、可生物降解性和生物相容性等优点而得到广泛的关注。然而,其固有的脆性,即低断裂伸长率和断裂强度严重限制了它在实际中的应用,但也因此吸引了更广泛的深入研究。本文综述了以生物可降解高分子增韧聚乳酸的研究进展,重点阐述了生物基聚酯,生物基弹性体,植物基生物高分子,天然橡胶和植物油以及生物大分子增韧聚乳酸的最新研究发展概况,同时提出了在经过改善韧性之后,聚乳酸存在的冲击韧性弱以及低结晶速率和低热转变温度等问题,并分析了未来的发展方向和需要关注的主题。     

新型喷雾干燥法制备LiFePO_4/C复合材料及其性能研究

通过新型喷雾干燥技术及热处理制备出具有球形二次形貌结构的纳米LiFePO4/C复合材料。首先合成了纳米FePO4颗粒(约20nm),并与Li2CO3和一定量的蔗糖均匀混合,对材料前驱体进行碳包覆,通过喷雾干燥获得了前驱体二次颗粒;经过热处理获得了由一次颗粒组成的二次颗粒。详细研究了碳含量对一次颗粒粒径及复合材料性能及形貌的影响,发现当LiFePO4/C复合材料中碳含量为5.3%(质量分数),样品拥有良好的形貌结构和最佳的性能,0.1,1和5C下的比容量分别为162,145和116mAh/g。     

Thickness dependence of structure and optoelectronic properties of In2O3:Mo films prepared by spray pyrolysis

The influence of thickness on the structural, morphological and optoelectronic behavior of Mo-doped In₂O₃ films, prepared by spray pyrolysis was investigated. The films had the cubic crystal structure for all the thicknesses investigated although it was found that a change in the preferred orientation and growth mode, from 2D to 3D, has occurred with an increase of film thickness. A small degradation in the optical transmittance has been observed with the increase of film thickness. The variation of electrical resistivity, mobility and charge carrier concentration with film thickness were also studied and the results discussed.     

Effects of spray drying process parameters on the solubility behavior and physical stability of solid dispersions prepared using a laboratory-scale spray dryer

Purpose: The purpose of this study is to determine the process parameters of the laboratory-scale spray dryer affecting the solubility behavior and physical stability of solid dispersions.

Methods: Solid dispersions of the model drug (nilvadipine or nifedipine) and hypromellose (HPMC) (w/w: 1/1) were prepared using the laboratory-scale spray dryer. As process parameters, nitrogen flow rate, sample concentration and pump speed were investigated. The samples were characterized by dissolution tests, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM), and nanoscale thermal analysis (Nano-TA). The physical stability was monitored after 7 months storage at 25°C.

Results: Solubility behavior and physical stability were improved by setting the low nitrogen flow rate and high sample concentration. DSC showed that the physical state depends on the spray drying conditions, whereas, every sample showed the similar morphology from SEM results. The difference of solubility behavior and physical stability were found to come from the microstructural phase separation of the spray dried particles using a novel analytical technique (Nano-TA).

Conclusions: This study demonstrated that nitrogen flow rate and sample concentration should be the critical parameters for the enhancements of the solubility and physical stability of solid dispersions.     

Structure and magnetic characterizations of cobalt ferrite films prepared by spray pyrolysis

Cobalt ferrite films were prepared by spray pyrolysis with post-annealing. For the as-deposited film, the differential scanning calorimetry measurement shows a crystallization peak at around 375 °C during the isochronal heating at 20 °C/min, and the X-ray diffraction pattern shows its amorphous-like characteristic. The isothermal post-annealings were performed for 2 h at various temperatures from 400 to 700 °C, leading to the crystallization of films, forming the spinel structure. The cross-sectional analysis with scanning electron microscopy shows that the film's thickness keeps almost constant after annealing, and the layered granular structure appears when the annealing temperature is high. The magnetic hysteresis loops of as-deposited and annealed films show that both the saturation magnetization and coercivity increase with the annealing temperature, due to the crystallization of CoFe₂O₄ phase.