Carbon dots derived from Poria cocos polysaccharide as an effective"on-off"fluorescence sensor for chromium(Ⅵ)detection / 药物分析学报

Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide,which is green source,cheap and easy to obtain,and has no pharmacological ac-tivity due to low water solubility.These carbon quantum dots exhibit good fluorescence stability,water solubility,anti-interference and low cytotoxicity,and can be specifically combined with the detection of Cr(Ⅵ)to form a non-fluorescent complex that causes fluorescence quenching,so they can be used as a label-free nanosensor.High-sensitivity detection of Cr(Ⅵ)was achieved through internal filtering and static quenching effects.The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(Ⅵ)concentration in the range of 1-100 μM.The linear equation was F0/F=0.9942+0.01472[Cr(Ⅵ)](R2=0.9922),and the detection limit can be as low as 0.25 μM(S/N=3),which has been successfully applied to Cr(Ⅵ)detection in actual water samples herein.

Interaction Between Lobetyolin and Bovine Serum Albumin by Steady-State Fluorescence and Molecular Docking / 中国实验方剂学杂志

Objective:The interaction between lobetyolin and bovine serumal bumin（bovine serum albumin，BSA）. Method:By the steady-state fluorescence analysis method，the molecular-docking，ultraviolet absorption spectrum and fluorescence quenching were used to calculate quenching constant and binding constant，the number of sites，the position，the force and the distance of lobetyolin-BSA system. In addition， the effect of metalionson quenching constant of the lobetyolin-BSA system was studied. Result:The quenching constant was 1.25×104 L·mol-1（37 ℃），the binding constant was 2.95×104 L·mol-1（37 ℃），and the number of sites was 1 and bound with site 1 in ⅡA of BSA， thermodynamic meters were ΔH=-19.374 kJ·mol-1，ΔS=23.1 J·mol-1·K-1， the interaction distance was 3.2 nm. Meta lions could accelerate the quenching. Conclusion:By the steady-state fluorescence technique，molecular-docking and ultraviolet absorption spectrum，the quenching mechanism of Lobetyolin-BSA is quiescent quenching，and the interactive force is electro static force. The Lobetyolin-BSA can be well combined. At the same time，it also shows that the molecular docking results are similar to the experimental results obtained by steady-state fluorescence analysis.

Study of the fluorescence quenching of 1-hydroxypyrene-3, 6, 8-trisulfonic acid by single-walled carbon nanotubes / Estudio de la disminución de la fluorescencia del ácido 1-hidroxipyreno-3, 6, 8-trisulfónico por medio de nanotubos de carbono de pared única / Estudo da diminuição da fluorescência do ácido 1-hidroxipireno-3, 6, 8-trisulfônico por meio de nanotubos de carbono de parede simples

Abstract This paper presents a study of the fluorescence quenching of 1-hydroxypyrene-3,6,8-trisulfonic acid (HPTS) in the presence of single-walled carbon nanotubes (SWCNT) using a fluorescence method. To investigate the quenching mechanism (dynamic or static) of HPTS, Stern-Volmer plots of single walled carbon nanotubes at different temperatures were used. The positive deviation from linearity in Stern-Volmer plots suggests that single walled carbon nanotubes follow a static quenching mechanism evidenced by the formation of a stable ground state complex. The results presented here help us to clarify the quenching mechanism in the interaction of a pyrene derived dye and carbon nanotubes. This study will open new possibilities in the use of the conjugate formed by SWCNTs and HPTS in the fabrication of a biosensor based on intracellular fluorescent probes.

Resumen Este artículo presenta el estudio de la desactivación de florescencia del ácido 1-hidroxipyreno-3,6,8-trisulfónico (HPTS) en presencia de nanotubos de carbono de pared única (SWCNT). Para investigar el mecanismo de desactivación (dinámico o estático) del HPTS se evaluaron nanotubos de carbono de pared única a diferentes temperaturas y se analizaron por medio de gráficas Stern-Volmer. La desviación positiva de la linealidad en las gráficas Stern-Volmer sugiere que los nanotubos de carbono de pared única actúan por medio de un mecanismo de desactivación estático, que se evidencia también por la formación de un complejo estable en estado fundamental. Los resultados presentados aquí nos ayudan a aclarar el mecanismo de desactivación de fluorescencia cuando tiene lugar la interacción entre un colorante derivado del pireno y nanotubos de carbono. Este estudio abre nuevas posibilidades para el uso de conjugados formados por SWCNT y HPTS en la fabricación de un biosensor basado en sondas fluorescentes intracelulares.

Resumo Este artigo apresentao estudo da diminuicao da fluorescência do ácido 1-hidroxipireno-3,6,8-trisulfônico (HPTS) em presença de nanotubos de carbono de parede simples (SWCNT). Para investigar o mecanismo da desativação (dinâmico ou estático) do HPTS se avaliaram nanotubos de parede simples em diferentes temperaturas e se analisaram por meio de gráficos Stern-Volmer. O desvio positivo de linearidade nos gráficos Stern-Volmer sugere que os nanotubos de carbono de parede simples atuam por meio de um mecanismo de desativação estática, que também se evidencia pela formação de um complexo estável fundamental. Os resultados apresentados aqui nos ajudam a aclarar o mecanismo de desativação de fluorescência quando ocorre a interação entre um corante derivado do pireno e nanotubos de carbono. Este estudo abre novas possibilidades para o uso de conjugados formados por SWCNT e HPTS na fabricação de um biosensor baseado em sondas fluorescentes intracelulares.

Study of the Interactions between Tetracyclines and Human Serum Albumin / 中国药房

OBJECTIVE:To discuss the interactions between tetracyclines(oxytetracycline,methacycline,tetracydine,and doxycycline)and human serum albumin(HSA).METHODS:The binding constants and the number of biding sites of tetracyclines with human serum albumin(HSA)at various temperatures were studied by using UV-visible absorption spectrum and spectrofluorimetry,and the enthalpy change(?H)entropy change(?S)were computed.According to the Frster nonradiative energy transfer theory,the critical distances R0 between donators and acceptors were derived.RESULTS:The thermodynamic parameters were as follows:?H0;R0:oxytetracycline:(1.82 nm),and methacycline(2.31 nm),tetracydine(2.98 nm),doxycycline(2.26 nm).CONCLUSION:Tetracyclines can all cause HSA's fluorescence quenching.The quenching mechanism is static quenching.The main acting force between them is electrostatic attraction.