DNA–Gold Nanozyme-Modified Paper Device for Enhanced Colorimetric Detection of Mercury Ions

Abstract

In this work, a paper device consisted of a patterned paper chip, wicking pads, and a base was fabricated. On the paper chip, DNA–gold nanoparticles (DNA–AuNPs) were deposited and Hg2+ ions could be adsorbed by the DNA–AuNPs. The formed DNA–AuNP/Hg2+ nanozyme could catalyze the tetramethylbenzidine (TMB)–H2O2 chromogenic reaction. Due to the wicking pads, a larger volume of Hg2+ sample could be applied to the paper device for Hg2+ detection and therefore the color response could be enhanced. The paper device achieved a cut-off value of 50 nM by the naked eye for Hg2+ under optimized conditions. Moreover, quantitative measurements could be implemented by using a desktop scanner and extracting grayscale values. A linear range of 50–2000 nM Hg2+ was obtained with a detection limit of 10 nM. In addition, the paper device could be applied in the detection of environmental water samples with high recoveries ranging from 85.7% to 105.6%. The paper-device-based colorimetric detection was low-cost, simple, and demonstrated high potential in real-sample applications.

The recent development of nanozymes for food quality and safety detection

“…Peng and coworkers designed a nanozyme-based paper chip for Hg 2+ detection. 40 DNA-gold nanoparticles (DNA-AuNPs) were chosen as the peroxidase mimic. Hg 2+ could be adsorbed on the surface of DNA-AuNPs, and the formed DNA-AuNPs/ Hg 2+ could show enhanced catalytic activity.…”

Lab-on-Paper Devices for Diagnosis of Human Diseases Using Urine Samples—A Review

“…Accordingly, the development of porous materials with a uniform pore size distribution is essential in improving the reproducibility and detection sensitivity of future lab-on-paper devices. Recent studies have reported that glass fiber paper and nitrocellulose membranes have a uniform pore size distribution [5,10,[16][17][18], and therefore offer an improved detection sensitivity and reproducibility. However, the manufacturing process for such materials is complicated and is more expensive than that for regular paper.…”

“…Consequently, lab-on-paper diagnostic platforms have aroused great interest in recent years. Compared to traditional macroscale systems, microfluidic lab-on-paper devices have many advantages, including ease of manufacture, good portability, low cost, a simple diagnostic procedure, and good disposability [3][4][5][6][7][8][9][10]. As a result, they are expected to find increasing use for POCT applications in coming years based on a variety of samples, including urine.…”

Recent advances in colorimetric sensors based on nanozymes with peroxidase-like activity

“…1 filter paper) loaded with DNA-Au NPs were also developed to fabricate a paper device for colorimetric detection of Hg 2+ . 56 DNA is an important substance that can control the peroxidase-like activity of various nanomaterials. 57 Thus, DNA-Au NPs could combine with Hg 2+ to produce a more stable DNA-Au–Hg alloy for enhancing peroxidase-like activity.…”