Study On Toxicity Of Human Keratinocytes Induced By BiOI Nanoparticles

BiOI as a novel semiconductor nanomaterials, has drawn great attentiondue to its open-layered structure and superior photocatalytic performance. Theincrease of research and application will inevitably result in significantexposure to the environment. However, the toxicological information of BiOIremains unknown. Therefore, it is rather imperative to carry out the researchand exploration for the toxicity of BiOI nanomaterials.Physico-chemical properties of different namomaterials always differswith each other. These properties such as size distribution, morphology, surfacegroups and charges often influence the toxicity induced by namomaterials. Invitro cellular screening provides a rapid and efficient method for toxicity studiesand is very suitable to develop mechanistic models for understanding thetoxicity mechanisms and the relationship between physicochemical propertiesand toxicity outcome. Therefore, study on the interaction of BiOI and theresulting effects on the organism at the cellular level as well as building evaluation methods for the safety assessment of BiOI is very important toensure the safe use of BiOI.Based on the above consideration, the present dissertation studied thecytotoxicity of BiOIs evaluated using HaCaT cells as a research model. The maincontents of this dissertation are focused on the following three aspects:1. Firstly, three BiOIs with typical morphologies of microspheres, flower likemicrospheres and nanosheets respectively, namely BiOI(EG), BiOI(ETH) andBiOI(H2O) were developed by a rapid method via water (H2O), ethanol (ETH)and ethylene glycol (EG) mediated solvothermal route for12h at the tempretatureof100°C. These BiOI nanomaterials provide raw materials for cytotoxityresearches. Secondly, the present study explored the impact of mixed solvents onthe preparation of BiOIs, the results showed that when there exists water in themixed solvents, particle sizes of BiOI increased and the micro-structures changedfrom microspheres to flower-like spheres; The morphologies and sizes of BiOIscould be controlled by the addition of PVP (a surfactant). It demonstrated thatparticle sizes of BiOI decreased for three BiOIs synthesized via water, ethanol,and ethylene glycol. The size of BiOI(EG) became smaller by increasing theamount of PVP.2. In this study, the in vitro cytotoxicity of three BiOIs, with typicalmorphologies of microspheres, flower like microspheres and nanosheetsrespectively, was investigated firstly toward a human keratinocytes cells byexposing24h. It was found that all BiOIs caused cytotoxicity in a concentration- dependent manner. The BiOI(H2O) showed the highest cytotoxicity of all. TheBiOIs had no cytotoxicity at low concentrations (0.5~10μg/mL), whereas the100μg/mLofBiOIcould trigger50%toxiceffectson HaCaTcells.Cell morphologiesalso encountered obvious changes, some became round and vesicular. Adherentcells decreased significantly and intercellular space increased.3. For inspecting the physico-chemical factors affected the cytotoxity andclarify the cytotoxic mechanism of different BiOI nanomaterials, cellularbiochemical indicators such as cell viability, membrane damage, oxidative stress,mitochondrial membrane potential, cell cycle and apoptosis togethering withmicrotechnique were tested. The results indicated that the possible cytotoxic modeof actions by BiOIs involved cell membrane disruption, depolarization of innermitochondrial membranes, cytotoxic response and ROS mediated apoptosis. Thedifference of the cytotoxity was relevant with the amount of perturbation and ROSaggregation. It was found that morphology, surface chemistry and surfaceproperties are the main factors affected the cytotoxity of BiOI. The nanosheet-shaped BiOI(H2O) with smaller hydrodynamic size tend to damage membranedamage by means of paracentesis and cause severer oxidative injury. Themicrosphere-shaped of BiOI(EG) was rich in hydroxyl groups and cause lessoxidative damage. The research on the cytotoxity and toxic mechanism ofdifferent BiOIs provides basis and support for biological safety assessment ofBiOI nanomaterials.