A label‐free DNAzyme‐cleaving fluorescence method for the determination of trace Pb²⁺ based on catalysis of AuPd nanoalloy on the reduction of rhodamine 6G

Abstract

The substrate chain of double-stranded DNA (dsDNA) could be specifically cleaved by Pb(2+) to release single-stranded DNA (ssDNA) that adsorbs onto the AuPd nanoalloy (AuPdNP) to form a stable AuPdNP-ssDNA complex, but the dsDNA can not protect AuPdNPs in large AuPdNP aggregates (AuPdNPA) under the action of NaCl. AuPdNP-ssDNA and large AuPdNPA could be separated by centrifugation. On increasing the concentration of Pb(2+) , the amount of released ssDNA increased; AuPdNP-ssDNA increased in the centrifugation solution exhibiting a catalytic effect on the slow reaction of rhodamine 6G (Rh6G) and NaH2 PO2 , which led to fluorescence quenching at 552 nm. The decrease in fluorescence intensity (ΔF) was linear to the concentration of Pb(2+) within the range 0.33-8.00 nmol/L, with a detection limit of 0.21 nmol/L. The proposed method was applied to detect Pb(2+) in water samples, with satisfactory results.

A new Rhodamine B derivative RBMAB as a highly selective and sensitive chemosensor for Fe3+ with low detection limit

“…15 Many of rhodamine derivatives have been designed and synthesized to display specific detection of Pb 2+ , Cu 2+ , Cd 2+ , Cr 3+ , Hg 2+ . [16][17][18][19][20][21][22][23][24][25][26][27] Although rhodamine based sensors for Fe 3+ have been reported a lot. Quite a lot of them haven't present the detection limit or have comparative high detection limit which hindered for low concentration detection.…”

POSS‐based fluorescence sensor for rapid analysis of β‐carotene in health products

“…Fluorescence spectroscopy is widely utilized in environmental monitoring, food safety, and biological analysis due to its ease of use, quick reaction, and high sensitivity. [11][12][13] Catalina and colleagues [14] used a fluorescence quenching technique to quantify β-carotene in food using fluorescein (F), eosin B (EB), and Congo red (CR) as fluorescent reagents. The detection limit of the approach was 0.47 mg/L.…”

A signal conversion system using binding‐induced strand displacement for disease biomarker assay

“…[ 18–20 ] Compared with traditional proteases, DNAzymes have the advantages of easy construction for point‐of‐care and on‐site assay because of their higher chemical and thermal stability. [ 21,22 ] Due to their intrinsic nature, they can be easily coupled with various DNA amplification technologies to improve detection sensitivity. [ 23,24 ] In our previously reported study, we constructed DNAzyme‐powered nanomachines to detect proteins by assembling nucleic acid components onto gold nanoparticles.…”