Serum albumin, the most abundant plasma protein in mammalian blood, shows significant effects on delivery and therapeutic efficacy of drugs, therefore, the investigation of binding interaction between serum albumin and drugs is vital and necessary. In the present study, the binding interaction of two aluminum (III) phthalocyanine (AlPc) derivatives, tetrasulfonate-and tetra-(p-sulfoazophenyl-4-aminosulfonyl)-substituted AlPc (complexes 1 and 2), with bovine serum albumin (BSA) was investigated by UV-Vis and fluorescence spectroscopy. Adding BSA to the Pc complexes in water caused remarkable changes in the Q-band of the Pc complexes, indicating an altered aggregation behavior. When titrating these AlPcs with BSA in PBS, the intrinsic fluorescence of BSA was significantly quenched through a static quenching process. The binding of Pc complexes to BSA might change its conformation, evidenced by the red shift of maximum emission wavelength. Furthermore, binding constants and binding sites were obtained and binding ability between the Pc complexes and BSA was assessed. Our results suggest that complexes 1 and 2 readily interact with BSA whereas the latter shows more affinity (with higher binding constant value) to BSA, implying the stretched amphiphilic substituents of complex 2 may contribute to their transportation in the blood.

The binding interaction between tetra-(p-sulfoazophenyl-4-aminosulfonyl)-substituted aluminum (III) phthalocyanine (AlPc), and two-serum albumins (bovine serum albumin (BSA) and human serum albumin (HSA)) has been investigated. AlPc could quench the intrinsic°uorescence of BSA and HSA through a static quenching process. The primary and secondary binding sites of AlPc on BSA were domain I and III of BSA. The primary binding site of AlPc on HSA was domain I, and the secondary binding sites of AlPc on HSA were found at domains I and II. Our results suggest that AlPc readily interact with BSA and HSA implying that the amphiphilic substituents AlPc may contribute to their transportation in the blood.

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The gas NO is a ubiquitous intercellular messenger that modulates a wide range of physiological and pathophysiological functions. But few studies were made to study the role of NO in the Ca 2+ release in dorsal root ganglion (DRG) neurons by confocal microscopy. Thus the objective of this study was to assess if NO has a role in Ca 2+ signaling in DRG neurons using confocal microscopy combined with special fluorescence probe Fluo-3/AM. A 100 μM concentration of the NO donors (Sodium Nitroprusside, Dihydrate, SNP) and NO synthase inhibitor (N G -Monomethyl-L-arginine, Monoacetate salt, L-NMMA) was used in the study. Results showed that the fluorescence intensity increased rapidly after injecting SNP, which indicated that SNP could enhance intracellular Ca 2+ release. And the fluorescence intensity shrank gradually with time and kept at a low level for quite a long period after loading with L-NMMA which indicated that L-NMMA could block intracellular Ca 2+ release. All these results demonstrated that NO was involved in the regulation of intracellular Ca 2+ release in the DRG neurons.