Amplified potentiometric transduction of DNA hybridization using ion-loaded liposomes.
Amplified potentiometric transduction of DNA hybridization based on using liposome 'nanocarriers' loaded with the signaling ions is reported. The liposome-amplified potentiometric bioassay involved the duplex formation, followed by the capture of calcium-loaded liposomes, a surfactant-induced release and highly-sensitive measurements of the calcium signaling ions using a Ca(2+) ion-selective electrode (ISE). The high loading yield of nearly one million signaling ions per liposome leads to sub-fmol DNA detection limits. Factors affecting the ion encapsulation efficiency and signal amplification are evaluated and discussed. The influence of the surfactant lysing agent is also examined. Such use of 'green' calcium signaling ions addresses the inherent toxicity of Ag and CdS nanoparticle tags used in previous potentiometric bioassays. The new strategy was applied for the detection of low levels of E. coli bacteria. It could be readily extended to trace measurements of other important biomolecules in connection to different biorecognition events. The attractive analytical performance makes liposomes a useful addition to the armory of potentiometric bioassays.
Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA.
Karin Y
KY
Chumbimuni-Torres
Jie
J
Wu
Corbin
C
Clawson
Michal
M
Galik
Anne
A
Walter
Gerd-Uwe
GU
Flechsig
Eric
E
Bakker
Liangfang
L
Zhang
Joseph
J
Wang
D001681:Biological Assay / Q000379:methods; D002118:Calcium / Q000737:chemistry*; D004247:DNA / Q000032:analysis*; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification; D017736:Ion-Selective Electrodes; D008081:Liposomes / Q000737:chemistry*; D009693:Nucleic Acid Hybridization / Q000379:methods*; D011199:Potentiometry / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry
D008081:Liposomes; D012336:RNA, Ribosomal, 16S; D013501:Surface-Active Agents; D004247:DNA; D002118:Calcium