The study of fluorescence characteristics and biochemical composition of a marine diatom Thalassiosira pseudonana 3H in light and dark cyclesI. The effects of nutrients

The effects of nutrients on the fluorescence characteristics and biochemical composition of marine diatom Thalassiosira pseudonana 3H in light and dark cycles were investigated with continuous culture. The results show that with the increase of nutrient deficiency, the ratio of enhanced fluorescence to fluorescence (Fd/F), cellular chloropyll-a and protein content of the algae decline, but the fluorescence yield (F/Chl) , DCMU enhanced fluorescence yield (Fd/Chl) , cellular carbohydrate content, carbohydrate/Chl, protein/Chl, carbohydrate/protein increase. The changing amplitude of each parameter is different at different nutrition status, sampling time and different light intensity.

Extraction,Optical Properties and Bio-Imaging of Fluorescent Composition From Moso Bamboo Shoots

A novel fluorescent composition was firstly isolated from natural winter fresh Moso bamboo shoots,and its optical properties were fully investigated by fluorescence spectroscopy.It could emit strong blue light both in solid and solution state,providing high fluorescence intensity in ethanol.The solution’s concentration and addition of water greatly affected the fluorescence intensity,high concentration and addition of much water could quench fluorescence.Apoptosis results showed that the fluorescent extract(0-25 mg/L)could not induce apoptosis of Hela cells.Confocal fluorescent microscopic imaging in human hepatocellular carcinoma cells(HepG2)was realized using the fluorescent extract,it could dye the whole cell well which was different from 4',6-diamidino-2-phenylindole(DAPI)only dying cell nucleus.The fluorescent extract may be candidate for future natural fluorescent bio-imaging agent.

Chondroitin Sulfate Fluorescence Biosensor Based on Graphere Quantum Dots Aggregating on CMC/CS Polyelectrolyte Microspheres

Here, we report an efficient fluorescence biosensor for chondroitin sulfate（CHS） based on polyelectrolyte microspheres of carboxymethyl cellulose（CMC） and chitosan（CS） composites inducing the aggregation of graphene quantum dots（GQDs）, calling CMC/CS-GQDs. The polyelectrolyte microspheres（CMC/CS microspheres） were fabricated by using anioniccationic electrostatic attraction between CMC and CS by high voltage electrostatic spray technology. The aggregating process of GQDs was based on the anionic-cationic electrostatic attraction as well. After combing with the polyelectrolyte microspheres, the fluorescence of GQDs disappeared. CHS, which widely consists in the cell surface of human beings and animals, carries a large number of negative charges on the surface. The addition of CHS enabled CHS and GQDs to compete with each other to composite with the CMC/CS microshpheres. As a result of the higher surface charge density of CHS, CMC/CS-CHS formed accompanied by the release of GQDs, and the fluorescence of the system recovered. The CHS content was detected by analyzing the system＇s fluorescence recovery, which suggested that the obtained fluorescence biosensor can accurately detect the concentration of CHS. The test results showed that the linear range of the fluorescence recovery for this biosensor with respect to CHS was 0~12.00 mg/mL, and the detection limit was 10-8 M. Besides, to test the stability of the biosensor, the CMC/CS-GQDs micropsheres persisted for one month, with a low fluorescence quenching of 9.48%. These results suggested that CMC/CS-GQDs can be utilized as efficient fluorescence biosensor for the detection of CHS. Moreover, the detection method was simple and efficient, and could be widely popularized.

Fluorescence Detection for H_2PO_4^- based on Carbon Dots/Fe^(3＋) Composite

A novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^（3＋） composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe^（3＋） composite was obtained by aqueous mixing of carbon dots and FeCl_3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe^（3＋） cations, resulting in the low fluorescence intensity of the carbon dots/Fe^（3＋） composite. On the other hand, H_2PO_4^- reduced the concentration of Fe^（3＋） by chemical reaction and enhanced the fluorescence of the carbon dots/Fe^（3＋） composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe^（3＋） composite and the concentration of H_2PO_4^-, and a fine linearity（R2=0.997） was found in the range of H_2PO_4^- concentration of 0.4-12 m M.