Dipstick Test

chewan

Scientists in the United States have produced a simple dipstick test for detecting lead levels in paints.


Easy-to-usebiosensors are important for detection of highly toxic trace metal ionsin the environment. Cross-linked gold nanoparticles modified withmetal-specific DNAzymes have been used in solution to create highlysensitive and selective colorimetric metal sensors based on the colourchange between aggregated (blue) and dispersed (red) goldnanoparticles. However, in solution the colour change can be difficultto distinguish and nanoparticle stability is poor, explains Yi Lu atthe University of Illinois at Urbana Champaign.


Lu andcolleagues have developed a sensor that uses non-cross-linked goldnanoparticle-DNA conjugates, bound to a lead-activated DNAzyme mountedon a solid dipstick platform. Lead ions in paint samples catalyse theenzymatic cleavage of the DNA-nanoparticle conjugates which arecaptured on the dipstick by a complementary DNA sequence. If the levelsof lead are present, a red line forms across the dipstick - similar toa pregnancy test kit.

Thedipstick is designed to give a positive result for lead levels over 1mgper cm2 - the value the U.S. Department of Housing and Developmentclassifies paint to be lead-based. Lu demonstrated that the dipsticktest produced the correct results on paint taken from walls even if thelead-based paint had been coated several times, simulating conditionsin many households.


Lu says that the detection range can betuned to the exact threshold defined for lead in different materialslike dust and water simply by using different DNA strands.


DuncanGraham at the University of Strathclyde, Glasgow, UK, an expert innanoparticle sensor systems, says, 'this nanoparticle based approachoffers advantages in terms of ease of use and performance. The designto generate a positive signal is highly innovative and the combinationof nanoparticles and DNAzyme is attractive for instrument-freequantitative analysis.'


'This technique makes bionanotechnologyeasy to use and applicable to everyday life,' concludes Lu. He addsthat the team are interested in expanding on this technique to detectother metal ions and also bacterial viruses and other toxins in water.


Victoria Steven

sumber : http://www.rsc.org/Publishing/ChemScience/index.asp

congrats :pompom: usaha terpuji ke arah memantapkan aplikasi bionanoteknologi :pompom:

mbhcsf

very innovative

how about its reliability and validity pulak yer , i am curious