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Response to “Comment on ‘Distribution of Nanoparticles in the See-through Medaka ( Oryzias latipes )’”

2021; National Institute of Environmental Health Sciences; Volume: 129; Issue: 12 Linguagem: Inglês

10.1289/ehp10585

1552-9924

Shosaku Kashiwada,

Gold and Silver Nanoparticles Synthesis and Applications

Vol. 129, No. 12 Response to LetterOpen AccessResponse to “Comment on ‘Distribution of Nanoparticles in the See-through Medaka (Oryzias latipes)’”is accompanied byDistribution of Nanoparticles in the See-through Medaka (Oryzias latipes)is a reply to letterComment on “Distribution of Nanoparticles in the See-through Medaka (Oryzias latipes)” Shosaku Kashiwada Shosaku Kashiwada Address correspondence to Shosaku Kashiwada, Division of Research and Planning, Kami Shoji Co. Ltd., 1-2-27 Mishima-Miyagawa, Shikokuchuo, Ehime, Japan 799-0404. Telephone: (81) 896-23-5400. Email: E-mail Address: [email protected] Division of Research and Planning, Kami Shoji Co. Ltd., Japan Search for more papers by this author Published:2 December 2021CID: 128001https://doi.org/10.1289/EHP10585AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit I appreciate Ceyhun’s interest in my early observations (Kashiwada 2006) on the penetration of nanoparticles into neural tissues of Oryzias latipes. Ceyhun finds my conclusions that “[t]hese results suggest that nanoparticles are capable of penetrating the blood–brain barrier and that they eventually reach the brain” and that “[n]anoparticles penetrated to reach the brain, although the amounts of nanoparticles that reached the brain were low” to be misleading. Before 2006 (the year of my publication), there was much less information on the functional structure of the blood–brain barrier (BBB) and the transportation of nanoobjects than is now available. In my study, the intact removed brain was subjected to direct observation. If cross sections of the brain were observed, it should be possible to observe fluorescence from the cut surfaces. However, it would be impossible to directly confirm the details of the nanoobjects’ crossing of the BBB.It would seem impossible for any solid nanoobject to penetrate the BBB, based on our fundamental understanding of its functional structure. However, nanoobjects have been shown to reach the brain of rats and fish via blood flow in investigations beyond my own (Yamago et al. 1995; Kashiwada 2006; Gonzalez-Carter et al. 2020; Ohta et al. 2020). Further, the ionic nature of particles may be important in determining passage through membranes. Kataoka et al. (2017) reported that water-dispersible single-walled carbon nanotubes coated with a cationic plastic polymer (W-SWCNT) exhibited embryotoxicity to medaka eggs, whereas other hydrophobic polyethylene glycol-functionalized SWCNT and nonfunctionalized SWCNT showed no toxicity. It is unclear how W-SWCNT caused the toxicity and, if the W-SWCNT could pass through biological membranes (e.g., the chorion), whether the pores on such membranes would be large enough to allow the passage of nanoobjects. Like the fluorescent polystyrene nanoparticles used in my early study, W-SWCNT had charged surface cations. Surface charge may control the behavior of nanoobjects in the aquatic ecosystem (Burns et al. 2013). Although some questions remain about the transit of nanoobjects through membranes, my early observation has provided some suggestion that cationic surface charge may be important, potentially in traversing tight junctions.ReferencesBurns JM, Pennington PL, Sisco PN, Frey R, Kashiwada S, Fulton MH, et al.2013. Surface charge controls the fate of Au nanorods in saline estuaries. Environ Sci Technol 47(22):12844–12851, PMID: 24144224, 10.1021/es402880u. Crossref, Medline, Google ScholarGonzalez-Carter D, Liu X, Tockary TA, Dirisala A, Toh K, Anraku Y, et al.2020. Targeting nanoparticles to the brain by exploiting the blood–brain barrier impermeability to selectively label the brain endothelium. Proc Natl Acad Sci USA 117(32):19141–19150, PMID: 32703811, 10.1073/pnas.2002016117. Crossref, Medline, Google ScholarKashiwada S. 2006. Distribution of nanoparticles in the see-through medaka (Oryzias latipes). Environ Health Perspect 114(11):1697–1702, PMID: 17107855, 10.1289/ehp.9209. Link, Google ScholarKataoka C, Nakahara K, Shimizu K, Kowase S, Nagasaka S, Ifuku S, et al.2017. Salinity-dependent toxicity of water-dispersible, single-walled carbon nanotubes to Japanese medaka embryos. J Appl Toxicol 37(4):408–416, PMID: 27534384, 10.1002/jat.3373. Crossref, Medline, Google ScholarOhta S, Kikuchi E, Ishijima A, Azuma T, Sakuma I, Ito T, et al.2020. Investigating the optimum size of nanoparticles for their delivery into the brain assisted by focused ultrasound-induced blood–brain barrier opening. Sci Rep 10(1):18220, PMID: 33106562, 10.1038/s41598-020-75253-9. Crossref, Medline, Google ScholarYamago S, Tokuyama H, Nakamura E, Kikuchi K, Kananishi S, Sueki K, et al.1995. In vivo biological behavior of a water-miscible fullerene: 14C labeling, absorption, distribution, excretion and acute toxicity. Chem Biol 2(6):385–389, PMID: 9383440, 10.1016/1074-5521(95)90219-8. Crossref, Medline, Google ScholarThe author declares he has no actual or potential competing financial interests.FiguresReferencesRelatedDetailsRelated articlesDistribution of Nanoparticles in the See-through Medaka (Oryzias latipes)6 July 2006Environmental Health PerspectivesComment on “Distribution of Nanoparticles in the See-through Medaka (Oryzias latipes)”2 December 2021Environmental Health Perspectives Vol. 129, No. 12 December 2021Metrics About Article Metrics Publication History Manuscript received5 November 2021Manuscript accepted8 November 2021Originally published2 December 2021 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. 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