Abstract
Extensive utilization increases the exposure of humans to Ag nanoparticles (NPs) via the oral pathway. To comprehensively address the action of Ag NPs to the gastrointestinal systems in real situations, i.e., the long-term low-dose exposure, we evaluated and compared the toxicity of three Ag NPs (20–30 nm with different surface coatings) to the human intestine cell Caco-2 after 1-day and 21-day exposures, using various biological assays. In both the short- and long-term exposures, the variety of surface coating predominated the toxicity of Ag NPs in a descending order of citrate-coated Ag NP (Ag-CIT), bare Ag NP (Ag-B), and poly (N-vinyl-2-pyrrolidone)-coated Ag NP (Ag-PVP). The short-term exposure induced cell growth inhibition and death. The cell viability loss appeared after cells were exposed to 0.7 μg/mL Ag-CIT, 0.9 μg/mL Ag-B or >1.0 μg/mL Ag-PVP for 24 h. The short-term and higher-dose exposure also induced reactive oxygen species (ROS) generation, mitochondrial damage, cell membrane leakage, apoptosis, and inflammation (IL-8 level). The long-term exposure only inhibited the cell proliferation. After 21-day exposure to 0.4 μg/mL Ag-CIT, the cell viability dropped to less than 50%, while cells exposed to 0.5 μg/mL Ag-PVP remained normal as the control. Generally, 0.3 μg/mL is the non-toxic dose for the long-term exposure of Caco-2 cells to Ag NPs in this study. However, cells presented inflammation after exposure to Ag NPs with the non-toxic dose in the long-term exposure.
Highlights
Nanoparticulate silver has been known for more than 100 years [1]
After 21-day exposure to 0.4 μg/mL Ag-CIT the cell viability dropped down to less than 50% and cells exposed to 0.5 μg/mL Ag-PVP kept normal as the control
We evaluated and compared the toxicity of three Ag NPs with different surface coatings to Caco-2 cells after 1-day and 21-day exposures to reflect the long-term and low-dose exposure of humans to Ag NPs
Summary
Nanoparticulate (colloidal) silver has been known for more than 100 years [1]. Nowadays silver nanoparticles (Ag NPs) have been used in personal care, household, medical products, and food packaging, owing to their broad-spectrum antimicrobial properties [2]. Investigated the cytotoxicity of 20 nm Ag NPs to SH-SY5Y and D384 cells after short-term (4–48 h) and long-tIenrt.mJ. TThhee rreepprreesseennttaattiivvee lliivvee//ddeeaadd ssttaaiinniinngg iimmaaggeess ooff CCaaccoo--22 cceellllss aafftteerr bbeeiinngg eexxppoosseedd ttoo tthhrreeee AAgg NNPPss wwiitthh ddiiffffeerreenntt ccoonncceennttrraattiioonnss ffoorr 2244 hh. Cell Cycle Assay of Caco-2 Cells after the Short-Term Exposure to Ag NPs 2.5. Cytokine IL-8 Secretion of Caco-2 Cells after the Short-Term Exposure to Ag NPs 2.62. .C6.yCtoyktionkeinIeLI-L8-S8eScercerteiotinonofoCf Cacaoc-o2-2CCelelslsaaftfteerrtthheeSShhoort-Teerrm Exposuurree ttooAAggNNPPss. To investigate whether the short-term exposure of Caco-2 cells to three Ag NPs causes the TinofTliaonmvimnevsatetiosgrtaiygtreaetsewpwohnehsteeht,ehtrherethItLhe-e8shssheocorrrte-tt-titeoernrmmofeeCxxappcoooss-2uurrceelloosffwCCaasaccaoon--2a2lycczeellldslsatfottoetrhtthrhereee2eA4AghgeNxNpPosPsscuarcuea.suTessheetshethe inflinafmrlaemsmuamlttsoairtnoyrFyriegrsueprsepo7nonsileslue, ,sttthrhaeeteIILLth--8a8tsstehecrcrereeetitAoiongnNofoPCfs adCcoaocn-2oo-tc2ienlclcserelwlassaeswtahanesaIlaLyn-z8aeldeyvzaeefltdewrahtfehtneert2h4tehhceeel2lx4vpioahsbuielrixetip.eTos hsuere. Viability and Membrane Integrity of Caco-2 Cells after the Long-Term Exposure to Ag NPs. After Caco-2 cells had been exposed to Ag-CIT and Ag-PVP for four cycles, the cell viability and vtetohxiaeplbeorsiesltevt2tetsihoeholxx.ite8tadeeippllhea.beeoorrVsatssisAesAeslo,sesniielelatwdfefettdAdibtth5haeaeeie0ssatLlgsatrrioo,een%nt-dDCCdwydCAA5e5aaHaaeI0L0gfiLgccnTf%%o-Ddo-DntdCCl-e-eaeeHH22aMaIrIfnvTTfiftccncttdheeleleeeaeeameelllerrnvnllvAltsblwsccdedenhsrgeehlhlaeoeAlhAl-aanlwlwnrPnssaddgege-eoVevhh--IcbbrrPnPnmaeaPyeeee-VtVvvectebeemmfeeoPnygPneoarttbbeeeferfseooioeatoeanxuxtxy2esersroppri1ununeo2x2coeorxfr1i1desedsecedCpexexddadd.dodpadopya.a.cosAosoytystoAAeseosos,-ssseede2ss,,oeAAddeoesxCfsstgxgxfhhhtocteAc-oc-oAoeoloCCeel0gpws0ww0pgpII...Tt4aTt4tnN4nNnfAAAtaμaμμePiPininngrngggggnssdd--/-t//CFCFmahCmaFAmAiteiItIgIgLiLTT0gLgTg0uLu.-o-AAa3.uarrPP3anAtetegrgμVVtg00μe--g99-g0PP.C.CT4g,4,-/9.mIC4feIft/tμμ,ToTorhhImmμLgrgtreeTffh//orfgorfamLmEooeeerfr/nuxuorL2La2iidmeprsrrs11.n.oclcTL2Tninsddodyysu1hoh.owaaccrleneTylyldoeveveesocshcrwasitsi..eaeao,e,y[AAlvlbbet2tlAlshchuiuiirc7c.lalegeclic]li[aAtablt.ooc2Nyclyrrriuree7cldPdvvllllicl]lolotiiasii.onanyvavssrrbsbgsigidaavliialoatlbtbiiiiooffnatistittylylsebtgetiihthtrrdidyyaeltercricofaatoocecetynneepeltplllhdldlrssssdllecroecelpllssl viabilities, we define the non-cytotoxic dose of Ag NPs at 0.3 μg/mL and lower [27].
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