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Effect of Transport on Distribution of Radioions and Radiometabolites
Published in Lelio G. Colombetti, Biological Transport of Radiotracers, 2020
Colloids, particles in suspension ranging in size from 1 mμ to 1 μ, are used in controlled particle size range to select the site of biologic distribution. The chemical and physical properties of the colloid are determined by charge-mediated interactions at the surface of the particles.4 The biologic distribution of a colloid is determined by size and surface charge of the particles, the dispersity of the colloid, and the polarity of the dispersion medium.3 The colloids which are foreign to the body are recognized by the plasma protein, opsonin, and phagocytized by macrophages in the reticuloendothelial (R.E.) system. Colloids are useful to image organs with a large number of R.E. cells. The liver, spleen, and bone marrow are dominant sites of deposition for radiocolloids. The relative distribution can be altered by changing the size of the particles. Particles less than 100 mμ are phagocytized to a greater extent in the marrow than in liver and spleen. Intermediate particles, 300 to 1000 mμ, are localized more in the liver, whereas particles in the 1 to 5 μ range are deposited more in the spleen.5 Particles larger than 5 μ are not true colloids and will settle out on standing. The size of the pulmonary capillary bed is about 8 μ. Thus, particles of 10 to 75 μ of labeled macroaggregates of albumin are trapped in the capillary bed and used for perfusion lung scans. Other particles used for lung scanning are iron hydroxide particles and albumin microspheres.
Environmental and Cytotoxicity Risks of Graphene Family Nanomaterials
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
Due to electrostatic charges and nonspecific protein binding many of the graphene family members tend to aggregate in biological fluids (Guo and Mei, 2014; Pan et al., 2012). To address the issue of poor dispersity and provide adequate suspension in physiological solutions, stabilizing agents or surfactants have previously been employed. The problematic toxicity of the latter, however, has been uncovered by previous experience with CNTs (Sanchez et al., 2011). On the other hand, the development of functionalized GFNs has provided improved solubility and biocompatibility and reduced environmental and cytotoxic impacts (Guo and Mei, 2014). Surface chemical functionalization alters the surface chemistry and charge of GFNs, modulating nanotoxicity (Rafiee et al., 2010). Surface functionalization or modification also commonly affects the blood retention and organ translocation of NMs, either placating or provoking toxicity (Bettinger et al., 2009). For example, hydrophilic carboxyl-functionalized graphene, with an increased degree of oxidation, exhibited intracellular internalization in comparison to the ill consequences of hydrophobic, non-functionalized graphene (Sasidharan et al., 2011).
Data Analysis
Published in Clive R. Bagshaw, Biomolecular Kinetics, 2017
However, this is an empirical relation where the value of n is a measure of dispersity, but it cannot be related to a particular physical parameter. An alternative approach is to assume that the rate constants take on a Gaussian or Lorentzian distribution, as is often done for fluorescence lifetime analysis [289]. However, in general, there is no way to distinguish between discrete multiexponential models and distribution models, and choice is based on the system under study [611]. Single-molecule measurements may provide a better characterization of the distribution of rate constants (Section 9.7).
Fabrication of solid lipid nanoparticles-based patches of paroxetine and their ex-vivo permeation behaviour
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2023
Fahad Pervaiz, Ayesha Saba, Haya Yasin, Manal Buabeid, Sobia Noreen, Abida Kalsoom Khan, Ghulam Murtaza
PDI is defined as a ratio that gives information about the homogeneity of the particle size distribution of the colloidal dispersion. The appropriate value of the polydispersity index is below 0.3 which represents a monodisperse and homogenous system [2]. Values of PDI of all formulations are below 0.3 except for F1 which shows 0.64 PDI are shown in Table 3. These results showed that all the formulations are homogenous and mono disperse systems except one formulation. F1 shows high PDI because of low lipid concentration. This occurs due to the high drug to lipid ratio as lipid concentration is less but the amount of drug remains the same [3]. Higher the poly dispersity index lower will be the homogeneity of particles in the dispersion [39]. Surfactant also helps to maintain low values of PDI and better homogeneity. Higher the concentration of surfactant, lower will be the value of PDI [3]. When F1, F2 and F3 were compared to check the effect of surfactant concentration on PDI, results showed that with the increase in the concentration of surfactant from 350 mg to 450 mg, the value of PDI lowers from 0.64 to 0.20.
Major difference in particle size, minor difference in release profile: a case study of solid lipid nanoparticles
Published in Pharmaceutical Development and Technology, 2021
Zhengwei Huang, Linjing Wu, Wenhao Wang, Wenhua Wang, Fangqin Fu, Xuejuan Zhang, Ying Huang, Xin Pan, Chuanbin Wu
Zetasizer Nano ZS90 instrument (Malvern Instruments Ltd., Worcestershire, United Kingdom) was used to examine particle size (light intensity weighted mean particle size) and zeta-potential. SLN were diluted 121 times with ultra-pure water, and 1 ml diluent was transferred for determination. The parameters were set as follows: equilibration time 120 s, temperature 37 °C, measuring angle 173° backlight. The particle size distribution was measured by scanning for nine times or more. The polydispersity index (PdI) was also determined, which was an index characterizing the degree of dispersity of size distribution. The zeta-potential was measured at least 12 times. Each sample was measured three times in parallel. The samples were stored for 10 days, and the particle size and zeta-potential were measured on the third, fifth, and tenth day to test the stability.
Engineered aluminum nanoparticle induces mitochondrial deformation and is predicated on cell phenotype
Published in Nanotoxicology, 2021
Henry Lujan, Marina R. Mulenos, Desirae Carrasco, Bernd Zechmann, Saber M. Hussain, Christie M. Sayes
Each of these steps in the loop (Figure 1(A)) - ranging aluminum exposure to mitochondrial dysfunction - was examined using microscopy techniques. The physicochemical characteristics of AlNPs were characterized before and after exposure to cells in culture. Before exposure, dynamic light scattering was used to measure the dispersity index (0.422 ± 0.018) which indicated a moderately disperse size population (i.e. value could range 0 to 1, where 0 indicates monodispersity and 1 indicates a highly heterogenous mixture). Dispersity index of nanoparticle suspensions as measured by dynamic light scattering was related to primary particle size of nanopowders as measured by transmission electron microscopy (TEM) (Figure 1(B)), where the average size of aluminum nanoparticles was 92.2 ± 2.57 nm. The hydrodynamic diameter was 455.77 ± 16.47 nm, indicating a high level of particle agglomeration. This was due to the hydrophobic nature of the nanopowder being force suspended in ultrapure water. Zeta potential was 8.44 ± 0.49 mV indicating colloidal instability (i.e. values >30 mV or <-30 mV indicate stability; values between −30 and 30 mV indicate instability). The particles were measured as 99.99% pure aluminum via inductively coupled plasma-mass spectrometry (Figure 1(C)). Taken together, the characteristics of the AlNPs demonstrate instability in solution and varied sizes that follow the proposed pathway in Figure 1(A).