Understanding the performance of a paper-based UV exposure sensor: The photodegradation mechanism of brilliant blue FCF in the presence of TiO photocatalysts in both the solid state and solution.

Rationale: The decolouration of brilliant blue FCF by the action of titanium dioxide (TiO ) under ultraviolet (UV) exposure has been recently reported as the basis of a paper-based sensor for monitoring UV sun exposure. The mechanism of brilliant blue FCF photodegradation in the presence of the photocatalyst and the resulting photoproducts are thus far unknown.

Methods: The UV-initiated photodegradation of brilliant blue FCF in the presence of TiO for both the aqueous and the solid state was investigated.

One-pot synthesis of high molecular weight synthetic heteroprotein dimers driven by charge complementarity electrostatic interactions.

Despite the importance of protein dimers and dimerization in biology, the formation of protein dimers through synthetic covalent chemistry has not found widespread use. In the case of maleimide-cysteine-based dimerization of proteins, we show here that when the proteins have the same charge, dimerization appears to be inherently difficult with yields around 1% or less, regardless of the nature of the spacer used or whether homo- or heteroprotein dimers are targeted. In contrast, if the proteins have opposing (complementary) charges, the formation of heteroprotein dimers proceeds much more readily, and in the case of one high molecular weight (>80 kDa) synthetic dimer between cytochrome c and bovine serum albumin, a 30% yield of the purified, isolated dimer was achieved.