הנדסת מים

46 141 | מגזין המים הישראלי הנדסת מים | DNAzyme-based biosensor for sub ppb lead ions detection using porous silicon Fabry- Pérot interferometer and optical contrast amplification D. Nanda Kumara, Shirly Reingewirtzb, Moshe Shemeshc, Ran Suckeveriened, Giorgi Shtenberga ABSTRACT Lead(Pb2+)contaminantsleachtotheterrestrial and aquatic ecosystems and continue to pose an enormous threat to public health and the environment. Herein, we present an optical sensing approach based on nanostructured porous silicon (PSi) Fabry-Pérot interferometers for real-timemonitoring of lead contaminants usingDNAzyme, a syntheticDNAsequencewith a functional catalytic region. The latter cleaved the complementaryDNA/RNA substrate strand at the ribonucleotide region in the presence of Pb2+, which resulted in a decrease in the average refractive index of the total porous void (blue shift). The interfacial optical contrast was enhancedby coupling silica nanoparticles to the complementary strand, thus improving the interferometer’s inherent performance. The catalytic activity of theDNAzyme-modified platform was monitored in real-time using reflective interferometric Fourier transform spectroscopy. Theoptimizedconditionsoffered means for accurate, rapid (~20min) andprecise detectionof Pb2+ in thedynamic linear rangeof 0.1 to 25 ppbwith a detection limit of 0.49 ppb (2.4 nM). Sufficient selectivity and specificity were attained against other commonly known metallic pollutants inwater sources (e.g., As3+, Cd2+, Cr3+, Cu2+andFe3+). Finally, thepractical applicability of the biosensor’s performance was demonstrated using real samples, such as ground, irrigation, tapwater and even plasma, while depicting satisfactory recovery values of 94-103% in compliance with the ICP-MS approach. Overall, the developed sensing platformcoupled tooptical signal amplification can be easily redesigned for targeting other metal pollutants posing risks towater sources and the environment for practical point-of-use. a. Institute of Agricultural Engineering, A.R.O., Volcani Institute, Rishon LeZion, Israel .b Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Israel c. Department of Food Science, Institute for Postharvest Technology and Food Sciences, A.R.O., Volcani Institute, Rishon LeZion, Israel d. Department of Water Industry Engineering, Kinneret Academic College, Israel