Nanoparticle Tracking Analysis of β-Casein Nanocarriers

Nanoparticle tracking analysis is an excellent tool for the characterization of mono- and polydisperse nanoparticle systems within the 10-2000 nm size range. The suitability of this technique relies on its ability to track all particles in solution simultaneously based on their Brownian motion giving an accurate size distribution. The tracked rate of particle movement is related to the particle's hydrodynamic radius using the Stokes-Einstein equation for determining the size distribution. Here we describe the characterization β-casein nanocarriers encapsulating a model hydrophobic compound, 8-anilino-1-naphthalenesulfonic acid, and the natural bioactive curcumin using the Malvern NanoSight NS300. Utilizing both normal light scattering and fluorescent modes of the NS300 enabled the differentiation of particles that had encapsulated the two fluorescent molecules and provided an accurate size distribution of the nanocarriers.

Nanoparticle Tracking Analysis for Multiparameter Characterization and Counting of Nanoparticle Suspensions

Nanoparticle tracking analysis (NTA) provides direct and real time visualization, sizing and counting of particulate materials between 10 nm and 1 μm in liquid suspension. The technique works on a particle by particle basis, relating the degree of movement under Brownian motion to the sphere equivalent hydrodynamic diameter particle size, allowing for high-resolution particle size distributions to be obtained within minutes. NTA has been used in studying protein complexes and protein aggregates, protein nanoparticles, metal nanoparticles, silica nanoparticles, viruses, cellular vesicles and exosomes to name just a few. Here we describe application of NTA to the analysis of model nanospheres of ~100 nm in liquid suspension, the size being representative of the middle of the NTA working range. The technique described can be adapted for use with nearly all particulate materials with sizes between approximately 10 nm and 1 μm, with appropriate adjustments to instrument settings.

Bacterial bioreactors: Outer membrane vesicles for enzyme encapsulation

Bacterial membrane vesicles, whether naturally occurring or engineered for enhanced functionality, have significant potential as tools for bioremediation, enzyme catalysis, and the development of therapeutics such as vaccines and adjuvants. In many instances, the vesicles themselves and the naturally occurring proteins are sufficient to lend functionality. Alternatively, additional function can be conveyed to these biological nanoparticles through the directed packaging of peptides and proteins, specifically recombinant enzymes chosen to mediate a specific reaction or facilitate a controlled response. Here we will detail mechanisms for directing the packaging of recombinant proteins and peptides into the nascent membrane vesicles (MVs) of Gram-negative bacteria with a focus on both active and passive packaging using both cellular machinery and engineered molecular systems. Additionally, we detail some of the more common methods for bacterial MVs purification, quantitation, and characterization as these methods are requisite for any subsequent experimentation or processing of MV reagents.

Isolation of Outer Membrane Vesicles Including Their Quantitative and Qualitative Analyses

Outer membrane vesicles (OMVs) are naturally secreted from the bacterial cell surface and therefore localized in the cell-free supernatant of bacterial cultures. Here we describe methods for crude and density gradient-purified OMV isolation and protocols for control analyses for protein profiling (SDS-PAGE), detection of indicator proteins (immunoblot analysis), lipid profiling (lipid extraction and LC-MS analysis), vesicle size determination (NanoSight), rough estimation of biomass (TrayCell™), as well as quantifications of defined OMV components, e.g., proteins (Bradford) and LPS (Purpald).

Lipidomic and proteomic analysis of exosomes from mouse cortical collecting duct cells

Exosomes are endosome-derived nanovesicles that are involved in cellular communication and signaling. Exosomes are produced by epithelial cells and are found in biologic fluids including blood and urine. The packaged material within exosomes includes proteins and lipids, but the molecular comparison within exosome subtypes is largely unknown. The purpose of this study was to investigate differences between exosomes derived from the apical plasma membrane and basolateral plasma membrane of polarized murine cortical collecting duct principal cells. Nanoparticle tracking analysis showed that the size and concentration of apical and basolateral exosomes remained relatively stable across 3 different temperatures (23, 37, and 42°C). Liquid chromatography-tandem mass spectrometry analysis revealed marked differences between the proteins packaged within the two types of exosomes from the same cells. Several proteins expressed at the inner leaflet of the plasma membrane, including α-actinin-1, moesin, 14-3-3 protein ζ/δ, annexin A1/A3/A4/A5/A6, clathrin heavy chain 1, glyceraldehyde-3-phosphate dehydrogenase, α-enolase, filamin-A, and heat shock protein 90, were identified in samples of apical plasma membrane-derived exosomes, but not in basolateral plasma membrane exosomes from mouse cortical collecting duct cells. In addition to differences at the protein level, mass spectrometry-based shotgun lipidomics analysis showed significant differences in the lipid classes and fatty acid composition of the two types of exosomes. We found higher levels of sphingomyelin and lower levels of cardiolipin, among other phospholipids in the apical plasma membrane compared to the basolateral plasma membrane exosomes. The molecular analyses of exosome subtypes presented herein will contribute to our understanding of exosome biogenesis, and the results may have potential implications for biomarker discovery.-Dang, V. D., Jella, K. K., Ragheb, R. R. T., Denslow, N. D., Alli, A. A. Lipidomic and proteomic analysis of exosomes from mouse cortical collecting duct cells.

Immuno-characterization of Exosomes Using Nanoparticle Tracking Analysis

Due to their size, small extracellular vesicles such as exosomes have been difficult to identify and to quantify. As the roles that exosomes play in intercellular signalling become clearer, so does their potential utility as both diagnostic biomarkers for disease and as therapeutic vectors. Accurate assessment of exosomes, both their number and their cargo, is important for continued advancement in the field of vesicle research. To that end, several technologies, including nanoparticle tracking analysis, have been developed to define the physical characteristics of vesicle preparations and determine their concentration. This chapter describes a method for identifying the size and concentration of a subpopulation of vesicles in biological samples, using nanoparticle tracking analysis. Characterization of distinct exosomes is enabled by specific marker antibodies, coupled to fluorescent quantum dots.

Quantitative real-time single particle analysis of virions

Providing information about single virus particles has for a long time been mainly the domain of electron microscopy. More recently, technologies have been developed—or adapted from other fields, such as nanotechnology—to allow for the real-time quantification of physical virion particles, while supplying additional information such as particle diameter concomitantly. These technologies have progressed to the stage of commercialization increasing the speed of viral titer measurements from hours to minutes, thus providing a significant advantage for many aspects of virology research and biotechnology applications. Additional advantages lie in the broad spectrum of virus species that may be measured and the possibility to determine the ratio of infectious to total particles. A series of disadvantages remain associated with these technologies, such as a low specificity for viral particles. In this review we will discuss these technologies by comparing four systems for real-time single virus particle analysis and quantification.

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We introduce four methods for virus particle-based quantification of viruses.

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They allow for quantification of a wide range of samples in under an hour time.

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The additional measurement of size and zeta potential is possible for some.