CdTe quantum dots (QDs) improve the affinities of baicalein and genistein for human serum albumin in vitro

Baicalein and genistein were studied for the affinities for human serum albumin (HSA) in the presence and absence of three CdTe quantum dots (QDs) with different sizes. Three typical CdTe QDs with maximum emissions of 535 nm (green-emitting, G-QDs), 598 nm (yellow-emitting, Y-QDs), and 654 nm (red-emitting, R-QDs) were tested. The fluorescence intensities of HSA decreased remarkably with increasing concentration of QDs. Baicalein resulted in an obvious blue-shift of the λ_em of HSA from 340 to 334 nm. However, the extents of blue-shifts induced by baicalein and genistein in the presence of QDs were much bigger than that in the absence of QDs. The quenching process of baicalein for HSA was easily affected by the QDs size than that of genistein. QDs increased the quenching constant from 136.97% to 162.24% for baicalein. However, QDs only increased the quenching constants from 20.56% to 32.23% for genistein. G-QDs, Y-QDs, and R-QDs increased the affinities of baicalein for HSA about 3.02%, 6.38% and 9.40%. G-QDs, Y-QDs, and R-QDs increased the affinities of genistein for HSA about 2.56%, 13.46% and 19.44%. The binding affinities of baicalein and genistein for HSA increased with increasing QDs size.     

Assessment of penetration of quantum dots through in vitro and in vivo human skin using the human skin equivalent model and the tape stripping method

Quantum dots (QDs) are rapidly emerging as an important class of nanoparticles (NPs) with potential applications in medicine. However, little is known about penetration of QDs through human skin. This study investigated skin penetration of QDs in both in vivo and in vitro human skin. Using the tape stripping method, this study demonstrates for the first time that QDs can actually penetrate through the stratum corneum (SC) of human skin. Transmission electron microscope (TEM) and energy diverse X-ray (EDX) analysis showed accumulation of QDs in the SC of a human skin equivalent model (HSEM) after dermal exposure to QDs. These findings suggest possible transdermal absorption of QDs after dermal exposure over a relatively long period of time.     

Determination of 17β-oestradiol by fluorescence immunoassay with streptavidin-conjugated quantum dots as label

A sensitive and selective method for the determination of 17β-oestradiol by fluorescence immunoassay (FIA) was established on the basis of quantum dots (QDs) as label. The complex of biotin-labelled anti-rabbit IgG and strepavidin conjugated by quantum dots (QD-SA) was regarded as a probe in this system and the strepavidin-biotin system as signal amplification system. After optimising the conditions of the immunoreaction, such as the concentration of the reagent and the pH of the buffer solution, the linear range and the limit of detection of 17β-oestradiol were 0.01-10,000 ng ml⁻¹ and 0.00542 ng ml⁻¹, respectively. This method was applied to determine oestradiol in water samples, with the percent recoveries in the range of 86-113%.     

硒代硫酸钠诱导HL60细胞凋亡——还原态硒的细胞毒性(英文)

细胞毒性研究认为Cd2+的释放是硒化镉(CdSe)纳米粒子的细胞毒性机制之一,而Se2-阴离子在纳米粒子中的毒性机制未知。作者研究了硒代硫酸钠(selenosulfate(SSeO3)2-)对HL60细胞的细胞毒性作用,发现10μmol/L的硒代硫酸钠可以显著抑制细胞活力,诱导细胞凋亡,出现了染色质凝聚、DNA ladder和G0/G1凋亡亚峰。线粒体膜电位显著降低的同时,促凋亡蛋白Bax的免疫荧光增加。结果表明还原态的Se2-阴离子有显著的细胞毒性作用,可以诱导HL60细胞凋亡。同时也暗示Se2-阴离子的释放可能是含Se2-纳米粒子(比如硒化镉的量子点)细胞毒性的机制之一。     

Development of a molecular detection method for naphthalene degrading pseudomonads

Abstract: A combined polymerase chain reaction amplification and reverse dot blot assay was designed for the detection of bacterial genes from soil and sediments. Total nucleic acids were directly extracted from soil using a lysozyme/sodium dodecyl sulfate/freeze-thaw method followed by rapid purification through gel electrophoresis. DNA was amplified using a highly stringent polymerase chain reaction with primers directed against the nahR regulatory gene present in plasmid NAH7 of Pseudomonas putida G7. The resulting amplification product was detected colorimetrically by reverse dot blot with an improved sensitivity ten-fold greater than traditional ethidium bromide staining after gel electrophersis. A lower limit of 10³, P. putida G7 cfu (g soil)⁻¹ was detected. This method was successfully employed to detect indigenous naphthalene-degrading bacteria from subsurface sediment collected from different locations of a naphthalene-contaminated site. Similar approaches could be developed for other soil-borne genetic markers.     

Spawning migration of Balon's ruffe into a Danubian side branch in Austria

The migrations of Gymnocephalus baloni Balon's ruffe into the side branch of the Danube at Schönbühel were restricted to the spawning season between the end of April and mid-June. The main environmental factor correlating with the immigration is assumed to be water temperature. Water level changes influence emigration.     

The effects of short-term exposures to ultraviolet radiation in the Hawaiian Coral Montipora verrucosa

Exposure to ultraviolet radiation (UVR, 290–400 nm) is an important abiotic factor that tropical marine organisms have been exposed to over evolutionary time. Additionally, UVR is known to cause coral bleaching independently and is an important synergistic factor in bleaching caused by thermal stress. Corals can avoid some of the damage associated with exposure to UVR by producing UVR-absorbing compounds such as mycosporine-like amino acids (MAAs). To examine the role of MAAs in the UVR photobiology of corals we conducted experiments on the Hawaiian coral Montipora verrucosa. M. verrucosa colonies were collected from 1, 5 and 10 m and exposed to three different UVR treatments for 3 days under constant visible irradiances equivalent to a depth of 0.15 m depth in Kane'ohe Bay. In addition to quantifying the MAA concentration of these corals several types of UVR-induced damage were measured to assess whether MAAs were providing protection. Quantum yields of photosystem II (PSII) fluorescence and excitation pressure on PSII were measured for each coral, and the formation of direct UVR damage to DNA was measured as cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine–pyrimidone photoproducts for the holobiont. All corals exhibited midday depressions in quantum yields, developed DNA photoproducts, and increased their MAA concentrations significantly as a result of UVR exposures. CPD accumulation in M. verrucosa was highest in corals from 1 m, which had the lowest MAA concentrations at the end of the experiment. Corals originally from 10 m showed the highest MAA concentration and lowest DNA damage in response to exposure to UVR. While corals from all collection depths displayed some sensitivity to increased irradiances of UVR, their respective levels of tolerance were clearly dependant on their previous light history.     

Spectroscopic characterization of streptavidin functionalized quantum dots

The spectroscopic properties of quantum dots can be strongly influenced by the conditions of their synthesis. In this work, we have characterized several spectroscopic properties of commercial, streptavidin functionalized quantum dots (QD525, lot 1005-0045, and QD585, lot 0905-0031, from Invitrogen). This is the first step in the development of calibration beads to be used in a generalizable quantification scheme of multiple fluorescent tags in flow cytometry or microscopy applications. We used light absorption, photoexcitation, and emission spectra, together with excited state lifetime measurements, to characterize their spectroscopic behavior, concentrating on the 400- to 500-nm wavelength ranges that are important in biological applications. Our data show an anomalous dependence of emission spectrum, lifetimes, and quantum yield (QY) on excitation wavelength that is particularly pronounced in the QD525. For QD525, QY values ranged from 0.2 at 480 nm excitation up to 0.4 at 450 nm and down again to 0.15 at 350 nm. For QD585, QY values were constant at 0.2 between 500 and 400 nm, but they dropped to 0.1 at 350 nm. We attribute the wavelength dependencies to heterogeneity in size and surface defects in the QD525, consistent with characteristics described previously in the chemistry literature. The results are discussed in the context of bridging the gap between what is currently known in the physical chemistry literature of quantum dots and the quantitative needs of assay development in biological applications.