ABSTRACT
A dual-transducer approach has been developed to decompose the optical signals of acid sensors in salt-containing concentrated acid solutions and to give acid and salt concentrations in concentrated LiCl-HCl, CaCl2-HCl, and AICl3-HCl solutions, respectively. The optical acid sensors in this approach are films of porous sol-gel SiO2 or SiO2-Nafion composite doped with low-pKa indicators. A novel linear relationship (dA/dCsalt)cCacid = beta x (dA0/dCacid)Csalt = 0 (A = absorbance of the sensor in a salt-containing HCl solution; A0 = absorbance of the sensor in a salt-free acid solution) was found, and the current approach is based on a set of nonlinear equations derived from this relationship.
ABSTRACT
The fabrication of microarrays containing PCR-amplified genomic DNA extracts from mice tumors on a Zetaprobe membrane using a modified thermal ink-jet printer is described. A simple and cost-effective procedure for the fabrication of microarrays containing biological samples using a modified bubble-jet printing system is presented. Because of their mass-produced design, ink-jet printers are a much cheaper alternative to conventional spotting techniques. The usefulness of the biochip microarray platform is illustrated by the detection of human fragile histidine triad (FHIT), a tumor suppressor gene. Subcutaneous carcinomas were induced with MKN/FHIT and MKN/E4 cell lines in immunodeficient mice. Several weeks into their development, the tumors from both groups of mice were removed and subjected to DNA extraction by lysis of tissue samples. The extracted DNA samples were amplified by PCR (30 cycles) using the primers corresponding to nucleotides 2 to 18 of the FHIT sequence. The resulting solution was transferred to the individual reservoirs of a three-color cartridge from a conventional thermal ink-jet printer (HP 694C), and arrays were printed on to a Zetaprobe membrane. After spotting, these membranes were used in a hybridization assay, using fluorescent probes, and detected with a biochip.
Subject(s)
Acid Anhydride Hydrolases , Microchemistry/methods , Oligonucleotide Array Sequence Analysis/methods , Animals , DNA, Neoplasm/analysis , DNA, Neoplasm/isolation & purification , Humans , Mice , Microchemistry/instrumentation , Neoplasm Proteins/genetics , Neoplasms, Experimental/diagnosis , Neoplasms, Experimental/genetics , Nucleic Acid Hybridization , Oligonucleotide Array Sequence Analysis/instrumentation , Transfection , Tumor Cells, Cultured/transplantationABSTRACT
An optical sensor has been developed for high-acidity ([H(+)] = 1-11 M) measurements. The sensor is made of thin films of silica sol-gels doped with an acid indicator. Acid- and base-catalyzed methods to make the sol-gel films have been studied, and the properties of the sol-gel sensors prepared by these methods are discussed. The acid-catalyzed method was found to give more robust films and has been optimized to prepare thin films which are mechanically and chemically stable for a period of at least 3 months. The performance of the sensors resulted in a relative standard deviation of less than 2.5%. The response time is short (1 s), and a small hysteresis was observed during reproducibility measurements with 2-10 M HCl solutions.
