Anticancer Activity Of Biogenic Selenium Nanoparticles On Human Liver Cancer HepG2 Cells And Its Applications In Sensors

Selenium?Se?is an essential trace element in living organisms.It is the active center of various selenoproteins in the body and plays a very important role in the health of the organism.Amongst its various forms,the red selenium nanoparticles?SeNPs?are with excellent biological activity and much lower acute toxicity.It was considered the most potent chemical form to the artificial selenium enrichment.Therefore,SeNPs has attracted much attention.At present,related research has focused on chemically synthesized SeNPs.However,there are very limited studies have been conducted about biogenic SeNPs.In this study,we used Rhodopseudomonas palustris strain N to reduce selenite to synthesize biogenic SeNPs?bioSeNPs?.Human liver cancer HepG2 cells were employed to evaluate the effects of bioSeNPs on the cell growth and the possible mechanisms involved in.BABL/c nude mice xenografted with HepG2 cells were also used to investigate the in vivo anti-tumor activity of bioSeNPs.At the same time,bioSeNPs-modified glassy carbon electrode was used to prepare SeNPs/GCE enzyme-free sensors for the determination of hydrogen peroxide?H₂O₂?.From the experiments,the following results were obtained:1.The R.palustris strain N could reduce SeO₃^-2 to red bioSeNPs.The bacteria exhibited significant tolerance to SeO₃^-2 up to 8.0 m mol/L concentration with an EC₅₀ value of 2.4 m mol�L^-1.After 9 d of cultivation,the presence of SeO₃^2-up to 1.0 m mol�L^-1 resulted in 99.9%reduction of selenite,whereas 82.0%,31.7%,and 2.4%reduction of SeO₃^-2 was observed at 2.0,4.0 and 8.0 m mol�L^-1 SeO₃^2-concentrations,respectively.2.Compared to sodium selenite,bioSeNPs has a similar tissue distribution after intragastrical administration to mice;bioSeNPs and sodium selenite showed comparable efficacy in increasing the activities of GSH-Px and TrxR in liver cell lines,mice blood and liver?P<0.05?.3.The R.palustris strain N was grown anaerobic with sodium selenite and produced stable bioSeNPs with an average particle size of165.9 nm.The MTT assay revealed that the biogenic SeNPs induces cell death of HepG2.The half effective inhibitory concentration of bioSeNPs on HepG2 was recorded at 5.412?mol�L^-1.Through the observation of cell morphology and flow cytometry,the apoptotic rate of HepG2 cells gradually increased with the increase of dose of bioSeNPs,showing a dose-dependent relationship.By measuring the activity of caspase-3,caspase-8 and caspase-9,the pathway of bioSeNPs inducing apoptosis in HepG2 cells may be involved in both mitochondrial and death receptor pathways.4.The volume and the wet weight of HepG2-bear nude mice received bioSeNPs were significantly decreased compared to the control,and the maximum inhibitory rate was 51.72%?P<0.05?;Compared with the positive control,hematology and biochemical indicators showed that bioSeNPs had no significant toxic and side effects on nude mice;The same results were obtained from the histological observation of major organs;after bioSeNPs supplementation,the selenium content in the liver,kidney,and spleen of nude mice was significantly increased?P<0.05?;the activities of SOD,CAT and GSH-Px in liver were significantly increased?P<0.05?and the levels of MDA were no significant changes?P<0.05?.5.A working electrode was subsequently modified by coating the surface of the glass/carbon electrode with bioSeNPs.The optimum amount of glass/carbon electrode modified by bio SeNPs was 5?L and the optimal pH of phosphate buffer solution was 7.0.The linear range of detection of H₂O₂ were from 0.1 to 5.0m mol�L^-1?R²=0.996?,while the calculated limit of detection resulted as 33.3?mol�L^-1.Studies have shown that bioSeNPs can be used for the fabrication of a low cost,sensitive,and environmentally friendly H₂O₂ biosensor.In conclusion,our results indicate that:The first,this study indicated that bioSeNPs were synthesized by green technology using R.palustris strain N.BioSeNPs and sodium selenite have similar absorption and utilization in vivo and in vitro,which will provide theoretical support for the wide application of bioSeNPs in the biological field.The second,bioSeNPs can inhibit the viability of the liver cancer HepG2 in vitro and in vivo,due to the bioSeNPs-induced apoptosis,which suggests that the bioSeNPs can potentially be developed into an alternative and complementary treatment for cancers such as liver cancer.The third,bioSeNPs exhibit good catalytic performance for H₂O₂and can be used for the fabrication of a low cost,sensitive,and environmentally friendly H₂O₂ biosensor.