High sensitive fluorophotometric determination of nucleic acids with Pyronine G sensitized by N,N-dimethylformamide

In Tris-HCl buffer (pH 8.0), the fluorescence of Pyronine G emitted at 552 nm was quenched by nucleic acids when excited at 525 nm. Adding N, N-dimethylformamide (DMF) as a sensitive media can enhance the sensitivity greatly. Based on the fluorescence reactions sensitive fluorimetric methods for nucleic acids at nanogram levels were proposed. Under the optimum conditions, the calibration curves were linear in the range of 0.0032 - 2.5 microg mL(-1) for ct DNA and 0.0024 - 2.5 microg mL(-1) for hs DNA. The limits of determination were 3.2 ng mL(-1) and 2.4 ng mL(-1) respectively. This method has good selectivity and high sensitivity. It has been applied to the determination of DNA in the synthetic samples and real samples with satisfactory results.

Interaction of m-nitrophenylfluorone-Mo(VI) complex as a probe with human serum albumin: a fluorescence quenching study

In this paper, the binding characteristics of human serum albumin (HSA) and m-nitrophenylfluorone (m-NPF)-molybdenum (Mo(VI)) complex have been studied by fluorophotometry. The binding constants are measured at different temperature. Based on the theory of Forster energy transfer, the binding distance and the energy transfer efficiency between m-nitrophenylfluorone-Mo(VI) complex and protein are obtained. According to the thermodynamic parameters, the main sort of binding force can be judged. The results indicate that HSA and m-NPF-Mo(VI) complex have strong interactions. The mechanism of quenching belongs to static quenching and the main sort of binding force is electrostatic gravitation.

Rapid determination of ultra trace amounts of residual protein in penicillin based on its enhancement effects of Rayleigh light scattering on trimethoxyphenlyfluorone (TM-PF)–Mo(VI) complex

This is a report on the ultra trace amount determination of protein in penicillin based on the interaction with trimethoxyphenlyfluorone (TM-PF)-molybdenum (Mo)(VI) complex in the presence of Triton X-100 microemulsion by Rayleigh light scattering (RLS). At pH 2.70, the weak RLS of TM-PF-Mo(VI) complex was enhanced greatly by the addition of proteins. Based on this, the interaction of TM-PF-Mo(VI) complex with proteins was studied and a new quantitative determination method for proteins was developed. This method is extremely sensitive (the linear range of the calibration curve was 0-80 ng mL(-1) for bovine serum albumin (BSA). The detection limit was 0.47 ng mL(-1)), simple, steady and free from interference of coexisting substances. TM-PF-Mo(VI) complex as a spectral probe can be used to the determination of the residual protein in penicillin samples successfully.