The Toxic Effects Of CuInS2/ZnS Quantum Dots To Rare Minnow(Gobiocypris Rarus)

Quantum dots?QDs?are semiconductor nanocrystals that have great potential for cell imaging,biomedical diagnostics,electronics,solar cells and other fields.Early research in this area focused on the synthetic and optical characterization of II-VI type QDs and IV-VI type QDs due to their excellent physical properties.However,most QDs contain toxic elements,such as Cd,Pb,Hg,Te and As,which limit their applications in practice.The potentially impact of human and environmental toxicity with QDs attract considerable attention with increased usage of QDs in industrial applications.QDs could enter into the water and produce toxicity to aquatic organisms,producing a potential harmful factor to the aquatic ecosystem environment.Fish play a vital role in control of the structure of food web and the stability of aquatic ecosystems.People have turned their attention to ternary I-III-VI compounds,and a promising alternative is the use of QDs based on Cd-free materials,such as CuInS₂.Recently,a direct band gap semiconductor,CuInS₂,has emerged as a promising alternative than conventional Pb,Cd,Te,Se and As based QDs because it has a larger stokes shift,a high molar extinction coefficient,and contains no highly toxic elements.It,CuInS₂ QD,has been gradually considered as the photoactive layer or sensitizers to try to fabricate the high efficiency solar cells.It has great potential of targeting capabilities in Hela cancer cells and using as fluorescent probes for in vivo biological imaging and quantum dot sensitized solar cells?QDSSCs?.Because known regarding the toxicity of CuInS₂/ZnS QDs in G.rarus is little,this information might be useful to assess the potential toxicity of QDs and to improve our understanding of their potential effects.The potential developmental toxicity of CuInS₂/ZnS QDs to G.rarus was investigated using an embryo bioassay.As well as,researching the reproductive toxicity of CuInS₂/ZnS QDs of the sexual mature G.rarus.Finally,researching the development toxicity of first filial generation of G.rarus.Part I,the G.rarus embryos were exposed to 0,50,100,200,400 or 800nmol/L QDs for 96hpf?hours post-fertilization?.We selected several critical monitoring endpoints,including survival rate,body length,average heart rate,relative enzyme activity?SOD activity and MDA content?,gene expression?Hsp70,Wnt8?,Mstn and Cyp1a?and DNA damage.Our study demonstrated that a significant impact on the early development of G.rarus embryos after CuIn S₂/ZnS QDs exposure.Embryos exposed to CuInS₂/ZnS QDs exhibited decreased survival rates and heart rates,altered body length,increased malformation,and a decreased hatching rate as well as many other toxic effects,including pericardial edema and bent spine.QDs can enter through the egg envelope into the body after 60 hpf exposure.QDs were observed in the heart,eyes,blood vessels and anus after 72 hpf exposure.The 72 hpf LC50?median lethal concentration?was measured to be 624.364nmol/L.After treatment with CuInS₂/ZnS QDs,the expression of Hsp70,Cyp1 a and Wnt8? were highly up-regulated,and Mstn expression was significantly down-regulated in the embryos.The OTM?Olive tail moment?was not significantly changed in the early embryos in response to QD exposure.As the exposure time was extended and as the concentration of QDs increased,OTM was significantly increased.The superoxidase dismutase?SOD?activity and malondialdehyde?MDA?levels were significantly increased after treatment with CuInS₂/ZnS QDs at certain concentrations.Part II,the sexual maturity of G.rarus were exposed to 0,100,200,400 or800nmol/L QDs?intraperitoneal injected CuInS₂/ZnS QDs?for 1d?days?,4d and 7d,the damage of gonad?including testis and ovaries?through ordinary HE dyeing technology and the damage of gonad to be observed by the TEM?Transmission electron microscope?.The genetic toxicity?DNA damage of perm cells?for the CuInS₂/ZnS QDs?with different concentration?at 1d,4d and 7d post intraperitoneal injected were tested using single-cell gel electrophoresis technique?SCGE?.Then,the quality of sperm were examined in this test.GIS and histopathology are treated as biomarkers for the gonad development.Our results showed that the sperm activation rate was no significant changes?p ? 0.05?.However,the sperm effective exercise time was decreased significant?p ? 0.05?after 36 h exposure.After 1d,OTM were significant increasedwhen comparing with control group.After 7d exposed,OTM was decreased significantly when compared with 1d QDs exposure groups?p ? 0.05?.Histological inspection of the ovaries revealed all stages of occyte development including primary,secondary and tertiary follicles at all exposure group.The female fish over 4d exposure to all QDs groups were similar to in control.The gonadosomatic indices?GIS?of female and male fish were no significant in CuInS₂/ZnS QDs treatments when comparing with control group?p?0.05?.The histological abnormality was observed in the male gonads including primary,secondary spermatocytes,were decreased and the cell-free zone were increased.The light micrographs of testis in adult G.rarus showed that mitochondria were observed swelling,some even rupture,and sperm tail slightly swollen in the 800nmol/L QDs.In addition,the intermediate germ cell of testes also changed significantly,including spermatocytes cell dissolved,mitochondrial swelling and even rupture,and sertoli cells were slightly swelling.After 7d exposure,the mitochondrial structure was normal,few swollen sperm and few dissolved spermatocytes.No obvious histological abnormality was observed in the female gonads of all the QDs exposure groups.Part III,in order to get the further observation of the development toxicity on embryos of QDs on the offspring.Some parameters of the offspring were tested,including embryos fertility,survival rate,heart rate,body length,malformation,hatching rate and tail bend frequency.Our results showed that spontaneous movements of offspring are significantly reduced,heart rates and malformation rate were significantly increased,the body length were significantly changed?p?0.05?.However QDs did not influence survival rate and hatching rate of offspring?p?0.05?.The main conclusion as follows:?1?CuInS₂/ZnS QDs exposure lead to developmental toxicity in G.rarus embryos,particularly in terms of their physical development.Embryos exposed to CuInS₂/ZnS QDs exhibited decreased survival rates and heart rates,altered body length,increased malformation,and a decreased hatching rate as well as many other toxic effects,including pericardial edema and bent spine.Besides,changed the expression of developmental related genes of in G.rarus larvae.The mRNA levels of Wnt8? and Mstn were unbalanced,which might partly explain the observed spine malformations.?2?Our study further demonstrated that CuInS₂/ZnS QDs exposure promotes oxidative stress and DNA damage responses in G.rarus larvae.?3?The early developmental toxicity of QDs may due to two aspects: one isROS-induced oxidative stress,leading to lipid peroxidation and DNA damage.On the other hand,due to their small size,QDs can enter the cell,which is associated with their nanoscale properties.?4?The QDs had adverse effects on reproduction including reduced the quality of sperm and and induce alterations in the gonadal structure.?5?Our results support observations that parental exposure to QDs could have adverse effects on the offspring.In the present study,the survival rate and hatching rate of G.rarus did not changed after exposed to CuInS₂/ZnS QDs,which suggesting that CuInS₂/ZnS QDs appear to be less lethal hazardous.