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Freezing has been widely recognized as the most common process for long-term preservation of perishable foods; however, unavoidable damages associated with ice crystal formation lead to unacceptable quality losses during storage. As an alternative, supercooling preservation has a great potential to extend the shelf-life and maintain quality attributes of fresh foods without freezing damage. Investigations for the application of external electric field (EF) and magnetic field (MF) have theorized that EF and MF appear to be able to control ice nucleation by interacting with water molecules in foods and biomaterials; however, many questions remain open in terms of their roles and influences on ice nucleation with little consensus in the literature and a lack of clear understanding of the underlying mechanisms. This review is focused on understanding of ice nucleation processes and introducing the applications of EF and MF for preservation of food and biological materials.

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Understanding interactions between proteins and nanoparticles (NPs) along with the underlying structural and dynamic information is of utmost importance to exploit nanotechnology for biomedical applications. Upon adsorption onto the NP surface, proteins form a well-organized layer that dictates the identity of the NP-protein complex named corona and governs its biological pathways. Given the high biological relevance, in-depth molecular investigations and applications of NPs-protein corona complexes are still scarce, especially since different proteins form unique patterns of corona and hence identification of biomolecular motifs at the interface is critical. In this work, we provide molecular insights and structural characterizations of the bionano interface of a popular food-based protein, bovine beta-lactoglobulin (β-LG), with gold nanoparticles (AuNPs) and the formation of corona complexes by combined molecular simulations and complementary experiments. Two major binding sites in β-LG were identified to be driven by citrate-mediated electrostatic interactions, while the associated binding kinetics and conformational changes in secondary structures were also characterized. More importantly, the superior stability of the corona led us to further explore its biomedical applications with examples of smart-phone based point-of-care biosensing of Escherichia coli (E. coli) and computed tomography (CT) of gastrointestinal (GI) tract through oral administration to probe GI tolerance and functions. Considering the biocompatibility, edible nature and efficient excretion through defecation, AuNPs-β-LG corona complexes have shown promising perspectives in future in vitro and in vivo clinical settings.

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The localized surface plasmon resonance (LSPR) effect of aggregating gold nanoparticles (AuNPs) has facilitated the development of colorimetric biosensors that can potentially be employed on site. We have developed an effective strategy to enhance the LSPR color-change signal by decoupling target detection and signal generation steps during immunobiosensing. The biosensor consists of streptavidin-coated AuNPs coupled with biotinylated antibacteria antibody as bifunctional linkers (BLs). While a BL can function both as an immunoreactor to bind to the target and as a cross-linker to aggregate AuNPs, its cross-linking function is largely limited when it binds with the target. We investigated the effect of number density (D n ) of AuNPs on the LSPR signal enhancement and the attendant improvement in detection sensitivity and rapidity of our biosensor by changing the particle size (5 to 50 nm diameter) when holding the absorbance of the AuNPs solution constant (Abs = 0.4 at 10× dilution). The performance enhancement of the biosensor was demonstrated by detecting a model target, streptavidin, and two bacteria, Escherichia coli and Legionella pneumophila. The results show that when Abs is held constant, the systems with lower D n but larger particles perform better. Therefore, our visual biosensing system can be suitably composed to maximize the limit of detection and rapidity.

IntroductionInduced pluripotent stem cells (iPSCs) have emerged as a promising cell source for immune-compatible cell therapy. Although a variety of somatic cells have been tried for iPSC generation, it is still of great interest to test new cell types, especially those which are hardly obtainable in a normal situation.MethodsIn this study, we generated iPSCs by using the cells originated from intervertebral disc which were removed during a spinal operation after spinal cord injury. We investigated the pluripotency of disc cell-derived iPSCs (diPSCs) and neural differentiation capability as well as therapeutic effect in spinal cord injury.ResultsThe diPSCs displayed similar characteristics to human embryonic stem cells and were efficiently differentiated into neural precursor cells (NPCs) with the capability of differentiation into mature neurons in vitro.When the diPSC-derived NPCs were transplanted into mice 9 days after spinal cord injury, we detected a significant amelioration of hindlimb dysfunction during follow-up recovery periods. Histological analysis at 5 weeks after transplantation identified undifferentiated human NPCs (Nestin+) as well as early (Tuj1+) and mature (MAP2+) neurons derived from the transplanted NPCs. Furthermore, NPC transplantation demonstrated a preventive effect on spinal cord degeneration resulting from the secondary injury.ConclusionThis study revealed that intervertebral discs removed during surgery for spinal stabilization after spinal cord injury, previously considered a “waste” tissue, may provide a unique opportunity to study iPSCs derived from difficult-to-access somatic cells and a useful therapeutic resource for autologous cell replacement therapy in spinal cord injury.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-015-0118-x) contains supplementary material, which is available to authorized users.

Ensuring consistently high quality and safety is paramount to food producers and consumers alike. Wet chemistry and microbiological methods provide accurate results, but those methods are not conducive to rapid, onsite testing needs. Hence, many efforts have focused on rapid testing for food quality and safety, the advances in nanotechnology, this sensing technique lends itself easily for further development on field-deployable platforms such as smartphones for onsite and end-user applications.