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Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG2000-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non-long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non-pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum. [ABSTRACT FROM AUTHOR]

The development of solid lipid nanoparticles (SLN) containing all-trans retinoic acid (RA) is an interesting approach to topical treatment of acne. SLN has potential for controlled release and follicular penetration, which can reduce adverse effects in comparison with conventional formulations. However, the encapsulation efficiency (EE) of RA in SLN is usually low, unless a high surfactant/lipid ratio is used. The aim of this work was to develop SLN with high EE using a low surfactant/lipid ratio. Different formulations of RA-loaded SLN were prepared using glyceryl behenate as lipid matrix. The particle size, EE, zeta potential and differential scanning calorimetry (DSC) were investigated. High EE in SLN was obtained with addition of amines. These results indicate that the utilization of amines is an interesting approach to improve the EE of RA in SLN using a low surfactant/lipid ratio. [ABSTRACT FROM AUTHOR]

Abstract: The chemical and mechanical stabilities of colored interference thin films on stainless steel were investigated by thermally aging these films at 150 °C for different aging times of 2, 4, 8, 16 and 256 h. The thermally aged films were morphologically characterized using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), and exhibited decreased porosity after thermal treatment. Fourier transform infrared spectroscopic (FTIR) analyses and depth sensing indentation tests confirmed that the sample aged for 2 h had better mechanical characteristics than samples that had not been thermally aged. Further, thermally aged samples exhibited increased hardness and abrasion wear resistance. [Copyright &y& Elsevier]

This study aimed to evaluate cell injuries in Bifidobacterium longum 5 1A caused by different microencapsulation processes. For this purpose, the probiotic was microencapsulated by emulsification using alginate with starch or chitosan as well as by spray drying using skim milk as the matrix. The microcapsules were characterized by atomic force microscopy, and cell viability was determined by plate count during storage (−20 °C/90 days). Under simulated gastrointestinal conditions cell injury was analysed using fluorescence of two probes followed by flow cytometry, and the hydrophobicity of cells was evaluated by bacterial adhesion to hexadecane. During storage, B. longum 5 1A remained above 7.51 log 10 CFU g −1 in all microcapsules. However, flow cytometry showed that only microencapsulation by spray drying maintained the cells without injury and ensured viability under simulated gastrointestinal conditions. The microstructural analysis showed few cells without coating in these microcapsules. In addition, flow cytometry showed the limitation of plate count method to assess cell viability, indicating that even when injured the bacterial cells grow in culture medium. Microencapsulation by spray drying also ensured the recovery of hydrophobicity during storage. Spray drying microcapsules can be an alternative to preserve the viability and functionality of probiotics to be incorporated into foods. [ABSTRACT FROM AUTHOR]