ABSTRACT
The effects of cetyltrimethylammonium bromide ( CTAB) , ascorbic acid, NaBH4 and AgNO3 , as well as the stirring time and reaction time on the preparation of gold nanorods synthesized with seedless growth method were studied. The optimum preparation conditions were obtained in the process of growth of gold nanorods. The gold nanorods prepared under different conditions were characterized by visible absorption spectroscopy and transmission electron microscopy ( TEM ) . Under the optimum conditions such as room temperature, 0. 1 mol/L CTAB, 96 μmol/L AgNO3 , 0. 97 mmol/L ascorbic acid, 1. 5 μmol/L NaBH4 and stirring for 25 s, micro-sized gold nanorods with uniform morphology, good dispersibility, small shaft width and high aspect ratio were prepared within 6 h. The gold nanorods were expected to be applied to the detection of mercury ion in water environment.
ABSTRACT
The effects of cetyltrimethylammonium bromide ( CTAB) , ascorbic acid, NaBH4 and AgNO3 , as well as the stirring time and reaction time on the preparation of gold nanorods synthesized with seedless growth method were studied. The optimum preparation conditions were obtained in the process of growth of gold nanorods. The gold nanorods prepared under different conditions were characterized by visible absorption spectroscopy and transmission electron microscopy ( TEM ) . Under the optimum conditions such as room temperature, 0. 1 mol/L CTAB, 96 μmol/L AgNO3 , 0. 97 mmol/L ascorbic acid, 1. 5 μmol/L NaBH4 and stirring for 25 s, micro-sized gold nanorods with uniform morphology, good dispersibility, small shaft width and high aspect ratio were prepared within 6 h. The gold nanorods were expected to be applied to the detection of mercury ion in water environment.
ABSTRACT
<p><b>OBJECTIVE</b>To study the characteristics of drug-resistant genetic mutation of rpoB in multiple drugs resistant bacillus tuberculosis (MDR-TB) among patients of pneumoconiosis complicated with pulmonary tuberculosis.</p><p><b>METHODS</b>A total of 114 clinical isolated strains of Mycobacterium tuberculosis were collected, MDR-TB were identified by conventional antimicrobial susceptibility test (AST). Their genomes DNA were extracted, the target genes were amplified by PCR, and the hot regions in the rpoB gene were analyzed by automated DNA sequenator.</p><p><b>RESULTS</b>The results by AST showed that there were 31 strains of MDR-TB in the 114 clinical isolated strains, the rate of drug resistance was 27.19% (31/114). No mutation of rpoB was identified in 10 rifampicin-sensitive strains that randomly chosen, while conformation changes were found in MDR-TB strains, and the mutation rate of rpoB was 93.55% (29/31) in resistant strains, mainly concentrated in codon 531 (45.16%, 14/31) and 526 (29.03%, 9/31), happened base substitutions, including 27 unit point mutation and 2 two point mutation.</p><p><b>CONCLUSIONS</b>The substitution of highly conserved amino acids encoded by rpoB gene results in the molecular mechanism responsible for RFP resistance in MDR-TB among patients of pneumoconiosis complicated with pulmonary tuberculosis. It also proves that rpoB gene is diversiform.</p>
Subject(s)
Adult , Aged , Humans , Male , Middle Aged , Bacterial Proteins , Genetics , DNA-Directed RNA Polymerases , Drug Resistance, Multiple, Bacterial , Genetics , Genes, Bacterial , Microbial Sensitivity Tests , Mining , Mutation Rate , Mycobacterium tuberculosis , Genetics , Pneumoconiosis , Microbiology , Sequence Analysis , Tuberculosis, Pulmonary , MicrobiologyABSTRACT
Objective To study the drug-resistant characteristics genetic mutation of rpoB in Mycobacterium tuberculosis L-forms among patients of pneumoconiosis complicated with pulmonary tuberculosis. Methods A total of 42 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected, including 31 drug-resistant strains. Their genomes DNA were extracted and target genes amplified by PCR. Hot regions in the rpoB gene were analyzed by automated DNA sequenator. Results No mutation of rpoB was identified in 11 rifampicin-sensitive strains while conformation changes were fotmd in 31 rifampicin-resistant strains. The mutation rate was 93.55% (29/31) in resistant strains, mainly concentrated in codon 531 (51.6%, 16/31) and 526 (32.26%, 10/31), happened base substitutions, including 27 unit point mutation and 2 two point mutation. The newly found mutation of codon 516 had not been reported by internal or overseas scholars. Conclusion The substitution of highly conserved amino acids encoded by rpoB gene resulted in the molecular mechanism was responsible for RFP resistance in Mycobacterium tuberculosis L-forms. It also proved that rpoB gene was in diversiform.