Bovine serum albumin (BSA) nonspecifically binds to well-dispersed multiwalled carbon nanotubes (MWCNTs), forming a stable bioconjugate. After accounting for the inner filter effect, we found the fluorescence intensity of BSA was quenched by MWCNTs in static mode, which was authenticated by lifetime measurements and Stern-Volmer calculations. The thermodynamic parameters DeltaG(o), DeltaS(o), and DeltaH(o) were -9.67 x 10(3) + 2.48 x 10(3) ln lambda J x mol(-1), 41.0 - 0.828 ln lambda J x mol(-1) x K(-1), and 7.30 x 10(3) + 2.23 x 10(3) ln lambda J x mol(-1) (lambda < 1 x 10(-4)), respectively, which shows a spontaneous and electrostatic interaction. Scatchard analysis and UV-visible results provide statistical data concerning changes in the microenvironment of amide moieties in response to different doses of MWCNTs, revealing different behavior of the BSA molecules. The absorption spectra also show that the tertiary structure of the protein was partially destroyed. The content of secondary structure elements of BSA was changed by the tubes. This work elucidates the interaction mechanism of BSA and MWCNTs from a spectroscopic angle.

The residue of the widely used veterinary drug oxytetracycline (OTC) in the environment (e.g., animal food, soils, surface water, and groundwater) is potentially harmful. Knowledge of its binding to proteins contributes to the understanding of its toxicity in vivo. This work establishes the binding mode of OTC with bovine serum albumin (BSA) under physiological conditions by spectroscopic methods and molecular modeling techniques. The inner filter effect was eliminated to get accurate data (binding parameters). On the basis of the thermodynamic results and site marker competition experiments, it was considered that OTC binds to site II (subdomain IIIA) of BSA mainly by electrostatic interaction. Furthermore, using the BSA model established with CPHmodels, molecular docking and some other molecular modeling methods were applied to further define that OTC interacts with the Arg 433, Arg 436, Ala 429, and Pro 516 residues of BSA. In addition, UV-visible absorption, synchronous fluorescence, and circular dichroism (CD) results showed that the binding of OTC can cause conformational and some microenvironmental changes of BSA. The work provides accurate and full basic data for clarifying the binding mechanisms of OTC with BSA in vivo and is helpful for understanding its effect on protein function during its transportation and distribution in blood.

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Metastable γ-Ga2O3 nanoflowers assembled from hexagonal nanopetals are successfully constructed by the oxidation of metallic Ga in acetone solution. The nanoflowers with a hollow interior structure exhibit a short response time and a large light-current-dark-current ratio under a relatively low bias voltage, suggesting an especially important potential application in solar-blind photodetection.

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