ABSTRACT
Pairs of PCR primers that targeted the archae/bacteriorhodopsin gene were used to clone the archaerhodopsin (aR) gene of Halorubrum xinjiangense strain BD-1(T), and this gene was sequenced and functionally expressed in Escherichia coli. Recombinant E. coli cells harboring the plasmid carrying this gene became slightly purple or blue depending on whether they were supplemented with all- trans retinal or 3,4-dihydroretinal, respectively, during induction with IPTG. The purple and blue membranes from the recombinant E. coli showed maximal absorption at 555 and 588 nm, respectively, which are different from maximal absorption at 568 nm of the wild-type purple membrane. Purple membranes from the recombinant E. coli and from strain BD-1(T) were investigated in parallel. The E. coli purple membrane was fabricated into films and photoelectric responses were observed that depended on the light-on and light-off stimuli.
Subject(s)
Archaeal Proteins/genetics , Genes, Archaeal , Halobacteriaceae/genetics , Amino Acid Sequence , Archaeal Proteins/chemistry , Base Sequence , Cloning, Molecular , DNA, Archaeal/genetics , Escherichia coli/genetics , Gene Expression , Molecular Sequence Data , Photochemistry , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Sequence Homology, Amino Acid , SpectrophotometryABSTRACT
The enhancement of a single strain DNA probe linked to the sensor surface is of crucial importance in DNA molecule recognition. By means of nanogold modification of the sensor surface in addition to the nanogold amplifier, DNA detection sensitivity higher than 10(-16)mol/L was obtained in a Quartz Crystal microbalance (QCM) system, much higher than the ordinary QCM sensor without surface modification by nanogold.
Subject(s)
Biosensing Techniques/methods , DNA/analysis , Gold Colloid/chemistry , DNA Probes/chemistry , Microscopy, Electron , Nanotechnology/methods , Nucleic Acid Hybridization/methods , Quartz/chemistry , Sensitivity and Specificity , Surface PropertiesABSTRACT
Thin films of poly(allylamine hydrochloride) (PAH) and bacteriorhodopsin (bR) embedded in purple membrane (PM) have been prepared by layer-by-layer (LBL) self-assembly technique. The results obtained by UV-Vis spectroscopy and atomic force microscopy (AFM) analysis showed that the biological activity of bR was preserved and PM fragments could be well oriented onto the ITO substrate. A photo-electrochemical cell with the structure of ITO/(PAH/PM)(n)/electrolyte (0.5M KCl)/Pt was fabricated and studied. The photocurrent peaks of (PAH/PM)(6) corresponding to light-on and light-off were about 200 and 100 nA/cm(2), respectively, with the former enhanced 30% higher than that of the reference films made of (PDAC/PM)(6).
Subject(s)
Biocompatible Materials/chemistry , Light , Polyamines/chemistry , Purple Membrane/chemistry , Bacteriorhodopsins/metabolism , Electric Conductivity , Microscopy, Atomic Force , Purple Membrane/physiology , Purple Membrane/ultrastructure , Spectrum AnalysisABSTRACT
A novel method using an amplifier with a cantilever and gold nanoparticles successfully to extend the length of the target for the specific and high sensitive detection of DNA was reported. When the size of gold nanoparticle is 50 nm, a sensitivity of 10(-15)M for the single base mutation detection has been achieved.
Subject(s)
Biosensing Techniques/methods , DNA/analysis , Base Sequence , DNA/chemistry , DNA Mutational Analysis , Gold/chemistry , Nucleic Acid Hybridization , Quartz/chemistry , Sensitivity and SpecificityABSTRACT
A novel amplified microgravimetric gene sensing system was developed using quartz crystal microbalance modified by gold nanoparticles anchored on its 1,6-hexanedithiol modified gold electrode surface, and ultrasensitive detection of DNA hybridization was accomplished at the level of at least 2 x 10(-16) M.