Quantum dots (QDs) are emerging as alternative or complementary tools to the organic fluorescent dyes currently used in bioimaging. QDs hold several advantages over conventional fluorescent dyes including greater photostability and a wider range of excitation/emission wavelengths. However, recent work suggests that QDs exert deleterious effects on cellular processes. This study examined the subcellular localization and toxicity of cadmium telluride (CdTe) QDs and pharmacological means of preventing QD-induced cell death. The localization of CdTe QDs was found to depend upon QD size. CdTe QDs exhibited marked cytotoxicity in PC12 and N9 cells at concentrations as low as 10 microg/ml in chronic treatment paradigms. QD-induced cell death was characterized by chromatin condensation and membrane blebbing and was more pronounced with small (2r=2.2+/-0.1 nm), green emitting positively charged QDs than large (2r=5.2+/-0.1 nm), equally charged red emitting QDs. Pretreatment of cells with the antioxidant N-acetylcysteine and with bovine serum albumin, but not Trolox, significantly reduced the QD-induced cell death. These findings suggest that the size of QDs contributes to their subcellular distribution and that drugs can alter QD-induced cytotoxicity.

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Despite many years of research, the industry still struggles with improving the shelf‐life of oxidizable food components (e.g. flavourings, polyunsaturated triglycerides, natural pigments, vitamins, flavourings etc.) or highly volatile components (e.g. aroma components in flavourings). Microencapsulation has been serving as an effective way to preserve flavour and other active ingredients, to control their release rate, and/or to mask their unpleasant odour or taste. Among a variety of microencapsulation methods, spray drying is the most widely used process in the food and beverage industries, due to its ease of processing and low operating cost. Unfortunately, most food encapsulating materials (hereafter called ‘wall materials’) are not the best barriers so the desired shelf‐life of encapsulated flavourings and other active ingredients is difficult to achieve. However, significant progress has been made through research on encapsulation formulations, processes, and evaluation technologies. This review summarizes the information in the scientific literature on how to optimize both the encapsulation matrix and the process to maximize product shelf‐life. This review presents literature from both the ‘oil’ and flavour areas. While there are some different issues in preserving highly unstable oils vs. flavourings, there is significant overlap. It is worthwhile to summarize, analyse and critique the literature in these two domains so both industries and academia can benefit from the sharing of this knowledge. First, factors that influence permeability of wall materials and microcapsules are discussed. Then, deterioration of flavourings or unsaturated lipids microencapsulated by spray drying is reviewed. The final section offers thoughts as to ways to improve upon the current practices. Copyright © 2015 John Wiley & Sons, Ltd.

Food products contain various active ingredients, such as flavors, nutrients, unsaturated fatty acids, color, probiotics, etc., that require protection during food processing and storage to preserve their quality and shelf life. This review provides an overview of standard microencapsulation technologies, processes, materials, industrial examples, reasons for market success, a summary of recent applications, and the challenges in the food industry, categorized by active food ingredients: flavors, polyunsaturated fatty acids, probiotics, antioxidants, colors, vitamins, and others. We also provide a comprehensive analysis of the advantages and disadvantages of the most common microencapsulation technologies in the food industry such as spray drying, coacervation, extrusion, and spray cooling. This review ends with future perspectives on microencapsulation for food applications.