Health and Environmental Risks of Synthetic Nanoparticles Assessed by Human Cell Lines

Author: Abdulmajeed Almutary

Almutary, Abdulmajeed, 2018 Health and Environmental Risks of Synthetic Nanoparticles Assessed by Human Cell Lines, Flinders University, College of Medicine and Public Health

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Toxicity of synthetic nanoparticles (NPs) to human keratinocyte cell line (HaCaT) and human colon carcinoma cell line (Caco-2) were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) , lactate dehydrogenase (LDH) and crystal violet assays. Eight nanoparticles were spiked in MTT and crystal violet assays and tested with HaCaT human skin cells to determine any possible interference. The MTT assay standard curve optical density (OD) measurements were shifted by the presence of trisilanol phenyl and trisilanol isooctyl polyhedral oligomeric silsesquioxane particles. The crystal violet standard curve OD measurements were significantly altered by AuNPs, but they did not affect the MTT assay. Carbon black decreased ODs in the MTT and crystal violet assays and was localised in the cell cytoplasm. The toxicity of 12-nm amorphous silica (SiO2) NPs following 4, 24 and 48h exposure was investigated using HaCaT cell line with MTT and crystal violet assays. Eleven concentrations of 12-nm SiO2 (ranging between 0.05-10 mg/mL) were tested. At 4, 24 and 48h exposure, a dose dependent increase in cell death with increasing concentration were observed when screened with the MTT assay. At 24h for concentrations ≥ 2 mg/mL, relative survival decreased when assayed by the MTT assay and relative cell number decreased when assayed with the crystal violet assay. After 48h treatment, cytotoxicity was observed at every treatment concentration assessed with the MTT and crystal violet assays. SiO2 nanoparticles are toxic to cultured human skin cells at a concentration as low as 0.05 mg/mL for 48h treatment when screen by the crystal violet assay. The toxicity of SiO2 NPs synthesised by the Stöber method and NDMA as a potent known carcinogen during chlorination on HaCaT and Caco-2 cell lines for 4, 24 and 48h detected by MTT and LDH assays. The morphology and size of SiO2 NPs was determined by SEM (200 nm in diameter). After exposure to SiO2 (concentrations 0.05–2mg/mL), the concentration 2 mg/mL inactivated LDH in both cell lines; however, it did not reduce their metabolic activity when MTT assay used. NDMA (concentrations 0.1–1000 µg/mL) inactivated LDH leakage in HaCaT and Caco-2 and reduced the metabolic activity of HaCaT cells at 48-h exposure. This suggests that a concentration of SiO2 <2 mg/mL used in water treatment can reduce the risk of nanomaterial toxicity to humans and possibly the ecosystems.

Thiolated silica (SiO2) NPs were synthesised using the Stöber method and then coated with low-fouling zwitterionic SBMA using thiol-ene addition. SEM revealed monodispersed spherical particles with DLS showing a small increase in nanoparticle average diameter after modification with SBMA. Toxicity of the SiO2-SBMA NPs (concentrations of 0.05–2.00mg/mL) was investigated using the MTT, LDH and crystal violet assays on the Caco-2 and HaCaT cell lines for 4, 24 and 48 h. The SiO2-SBMA NPs increased LDH leakage and decreased relative cell number at 2.00 mg/mL, as clearly observed after the particles were exposed to UV light. These results indicate that concentrations ≤1.50 mg/mL of SiO2-SBMA is of low toxicity are biocompatible and show potential as a chemotherapy drug conjugate.

Keywords: toxicity, nanoparticle, MTT assay, interference, crystal violet, trisilanol isooctyl, trisilanol cyclopentyl, trisilanol cyclohexyl, trisilanol phenyl, CdS QDs, silicon dioxide, AuNPs, carbon black, POSS particles

Subject: Medical Biotechnology thesis

Thesis type: Doctor of Philosophy
Completed: 2018
School: College of Medicine and Public Health
Supervisor: Chris Franco