Citric acid modifies surface properties of commercial CeO2 nanoparticles reducing their toxicity and cerium uptake in radish (Raphanus sativus) seedlings.
Little is known about the mobility, reactivity, and toxicity to plants of coated engineered nanoparticles (ENPs). Surface modification may change the interaction of ENPs with living organisms. This report describes surface changes in commercial CeO2 NPs coated with citric acid (CA) at molar ratios of 1:2, 1:3, 1:7, and 1:10 CeO2:CA, and their effects on radish (Raphanus sativus) seed germination, cerium and nutrients uptake. All CeO2 NPs and their absorption by radish plants were characterized by TEM, DLS, and ICP-OES. Radish seeds were germinated in pristine and CA coated CeO2 NPs suspensions at 50mg/L, 100mg/L, and 200mg/L. Deionized water and CA at 100mg/L were used as controls. Results showed ζ potential values of 21.6 mV and -56 mV for the pristine and CA coated CeO2 NPs, respectively. TEM images showed denser layers surrounding the CeO2 NPs at higher CA concentrations, as well as better distribution and smaller particle sizes. None of the treatments affected seed germination. However, at 200mg/L the CA coated NPs at 1:7 ratio produced significantly (p ≤ 0.05) more root biomass, increased water content and reduced by 94% the Ce uptake, compared to bare NPs. This suggests that CA coating decrease CeO2 NPs toxicity to plants.
Chemistry Department, The University of Texas at El Paso, 500 West University Av., El Paso, TX 79968, USA.
J
J
Trujillo-Reyes
A R
AR
Vilchis-Nestor
S
S
Majumdar
J R
JR
Peralta-Videa
J L
JL
Gardea-Torresdey
D000042:Absorption; D018533:Biomass; D002563:Cerium / Q000737:chemistry / Q000493:pharmacokinetics*; D019343:Citric Acid / Q000737:chemistry*; D018525:Germination / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D018517:Plant Roots / Q000187:drug effects; D031224:Raphanus / Q000187:drug effects*; D036226:Seedlings / Q000187:drug effects; D012639:Seeds / Q000187:drug effects; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis
D014874:Water Pollutants, Chemical; D019343:Citric Acid; D002563:Cerium; C030583:ceric oxide
Capping; CeO(2) NPs; Root biomass; Seed germination; Uptake