In addition, the daily use of toners and printing inks enhances the potential for carbon black exposure in an indoor homes or office environments (Morimoto et al., 2010 Yang et al., 2007). Because of its wide usage and high potential for exposure through inhalation, there is a high risk of occupational exposure in various industries (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, 1996 Morfeld and McCunney, 2010). Carbon black is an industrial chemical produced and consumed for diverse industrial purposes including reinforcement of rubber and coloring for dyestuffs (Baan, 2007). However, size dependency in particle toxicity remains largely unknown at this stage and is still controversial (Madl and Pinkerton, 2009).Ĭarbon black is a particulate form of pure elemental carbon that is produced by partial combustion or pyrolysis of gaseous or liquid hydrocarbons under controlled conditions (Valberg et al., 2006). This may be due to a characteristic high surface to volume ratio which makes the particles very reactive or catalytic (Fubini et al., 2010). Ultrafine particles are known to impose higher health risks on living organisms than fine particles (Stone et al., 2007). Ultrafine particles exhibit size-related properties that differ significantly from those observed in fine particles or bulk materials, and on the whole, 100 nm is regarded as a critical border to exhibit distinct properties overlapped between find and ultrafine particles (Stone et al., 2007 Nemmar et al., 2002). Particles less than 10 mm are generally called fine particles, and particles with at least one dimension between 1 and 100 nm are called ultrafine particles or nanoparticles. Toxicity of particle is largely dependent on particle size (Brook et al., 2010 Kreyling et al., 2006 Sager and Castranova, 2009). Therefore, the characterization of particle properties is a prerequisite for toxicity studies. These are principally determined by diverse physicochemial characteristics of particles such as agglomeration/aggregation, particle size, specific surface area, surface charge, radical formation potential, and so on (Fubini et al., 2010 Madl and Pinkerton, 2009). Health risk imposed by particle exposure has been widely investigated, including lung/pulmonary toxicity, cardiovascular effects, immunotoxicity, neurotoxicity and carcinogenicity (Xia et al., 2009 Boverhof and David, 2010). Along with the application to biomedical sciences, safety issues surrounding their use is also attracting a great deal of attention (Ai et al., 2011). A growing number of engineered particles are being newly developed and used in the manufacturing industry (Castranova, 2011). The methods established in this study could disperse carbon black into ultrafine and fine particles, and may serve as a useful model for the study of particle toxicity, particularly size-related effects.Įngineered particles are receiving much attention with the rapid development of particle sciences. Electron microscopy confirmed the typical aciniform structure of the carbon arrays however, zeta potential measurement failed to explain the dispersibility of carbon black. In contrast, 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) exhibited little effect. Application of Tween 80 along with sonication reduced the size of N330 to less than 100 nm, and dispersed N990 larger than 100 nm (73.6 ± 28.8 and 80.1 ± 30.0 nm for N330 and 349.5 ± 161.8 and 399.8 ± 181.1 nm for N990 in KR and PSS, respectively). However, sonication was not enough to disperse N330 less than 100 nm in either KR or PSS. Large clumps were observed in all dispersion preparations however, sonication improved dispersion - averaged particle sizes for N330 and N990 were 85.0 ± 42.9 and 112.4 ± 67.9 nm, respectively, in plasma the corresponding sizes in culture media were 84.8 ± 38.4 and 164.1 ± 77.8 nm. Carbon black with a distinct particle size, N330 and N990 were suspended in blood plasma, cell culture media, Krebs-Ringer’s solution (KR), or physiological salt solution (PSS). Here, biocompatible methods were established to disperse carbon black into ultrafine and fine particles which are generally distinguished by the small size of 100 nm. Carbon black has been used as a surrogate to investigate the biological effects of carbonaceous particles. Dispersion in the aqueous phase has been both a critical impediment to and a prerequisite for particle studies. The biological activity of particles is largely dependent on their size in biological systems.
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