Novel Terbium Chelate Doped Fluorescent Silica Nanoparticles

Novel terbium chelate doped silica fluorescent nanoparticles were prepared and characterized. The preparation was carried out in water-in-oil （W/O） microemulsion containing monomer precursor （pAB-DTPAA-APTEOS）, Triton X-100, n-hexanol, and cyclohexane by controlling copolymerization of tetraethyl orthosilicate and 3-aminopropyl-triethyloxysilane. The nanoparticles are spherical and uniform in size, about 30 nm in diameter, strongly fluorescent, and highly stable. The amino groups directly introduced to the surface of the nanoparticles using APTEOS during preparation made the surface modification and bioconjugation of the nanoparticles easier. The nanoparticles are expected as an efficient timeresolved luminescence biological label.

Toxic effects of metal oxide nanoparticles and their underlying mechanisms

Nanomaterials have attracted considerable interest owing to their unique physicochemical properties.The wide application of nanomaterials has raised many concerns about their potential risks to human health and the environment.Metal oxide nanopartides（MONPs）,one of the main members of nanomaterials,have been applied in various fields,such as food,medicine,cosmetics,and sensors.This review highlights the bio-toxic effects of widely applied MONPs and their underlying mechanisms.Two main underlying toxicity mechanisms,reactive oxygen species（ROS）-and non-ROS-mediated toxidties,of MONPs have been widely accepted.ROS activates oxidative stress,which leads to lipid peroxidation and cell membrane damage.In addition,ROS can trigger the apoptotic pathway by activating caspase-9 and-3.Non-ROS-mediated toxicity mechanism includes the effect of released ions,excessive accumulation of NPs on the cell surface,and combination of NPs with specific death receptors.Furthermore,the combined toxicity evaluation of some MONPs is also discussed.Toxicity may dramatically change when nanomaterials are used in a combined system because the characteristics of NPs that play a key role in their toxicity such as size,surface properties,and chemical nature in the complex system are different from the pristine NPs.

Ba_(1-x)Sr_xMgSiO_4:Eu^(2+),Mn^(2+): A novel tunable single-matrix tricolor phosphor for W-LED

The Ba1-xSrxMgSiO4：Eu2＋,Mn2＋ phosphors were prepared by solid-state reaction. Their photoluminescence properties were inves-tigated with fluorescence spectrum and CIE chromaticity. The emission color of Eu2＋ in Ba0.98-xSrxMgSiO4：0.02Eu2＋ could be tuned from green to blue by adjusting the content of Sr2＋. The blue emission of Eu2＋ overlapped well with the excitation spectra of Mn2＋, leading to an ef-ficient energy transfer from Eu2＋ to Mn2＋ in Ba0.98-xSrxMg1-ySiO4：0.02Eu2＋,yMn2＋. Ba0.93Sr0.03Mg1-ySiO4：0.02Eu2＋,yMn2＋ could emit three ef-ficient broad bands at 440, 530 and 640 nm. The emission color of Ba0.93Sr0.03Mg1-ySiO4：0.02Eu2＋,yMn2＋ could be tuned from greenish blue to yellowish white by increasing the content of Mn2＋ from 0 to 0.1. By changing the content of Sr2＋/Mn2＋, white-light with different hues could be conveniently obtained in the Ba1-xSrxMgSiO4：Eu2＋,Mn2＋ phosphors. The results showed that Ba1-xSrxMgSiO4：Eu2＋,Mn2＋ is a promising single-phased tricolor phosphor in the fabrication of W-LED.