An optical biosensor based upon glucose oxidase immobilized in sol-gel silicate matrix.

Glucose oxidase immobilized in a transparent silicate gel prepared by a sol-gel method was used as a simple solid-state optical biosensor for glucose. The sensor was based upon the measurement of initial rates of reduction of the FAD prosthetic group of the enzyme in the presence of various concentrations of glucose. The analytical range of the sensor was 1-100 mM, and the measurement time was 2 min.

Properties of trypsin and of acid phosphatase immobilized in sol-gel glass matrices.

Trypsin and acid phosphatase-containing silica sol-gel glasses were obtained by mixing a solution of an enzyme with polyethylene glycol (PEG) 6000 and tetramethoxy orthosilicate at room temperature, followed by gelation and drying. Activity of the immobilized trypsin toward small substrates, such as N-benzoyl-L-arginine-4-nitroanilide at its Km, for the best preparations equaled that of the soluble enzyme. Polylysine (M(r) less than or equal to 13,000) and aprotinin (M(r) = 6,500) inhibited this activity.

Structure-activity relationships in mutagenicity and in nucleophilic ring opening of N-(arylmethyl)phenanthrene 9,10-imines.

Ten derivatives of N-benzylphenanthrene 9,10-imine with different substituents on the phenyl ring were synthesized and subjected to mutagenicity tests in Salmonella typhimurium TA100. While electron donating groups were found to enhance the biological activity, electron attracting and bulky substituents lowered the mutagenic potency. A similar dependence on the electronic structure was observed in triethylamine/acetonitrile-promoted interaction of the title imines and 4-nitrothiophenol.

Mutagenicity of N-substituted phenanthrene 9,10-imines in Salmonella typhimurium and Chinese hamster V79 cells.

We previously showed that some (nonsubstituted) aziridines derived from polycyclic aromatic hydrocarbons (arene imines) elicit various mutagenic and genotoxic effects in bacteria and mammalian cells and that these arene imines are active at much lower concentrations than the corresponding epoxide analogues. In the present study, N-substituted derivatives of phenanthrene 9,10-imine were investigated. All 10 derivatives studied showed direct mutagenicity in Salmonella typhimurium TA100.

Structure-activity relationships in the mutagenicity of N-substituted derivatives of phenanthrene-9,10-imine.

A series of K-region, N-substituted phenanthrene imines were tested for mutagenicity in Salmonella typhimurium TA100. All chemicals were mutagenic in the absence of an exogenous metabolic activation system. The apparent decay times of the mutagenic species in diffusion plates and their alkylating activities were also measured.