Colorimetric determination of mercury(II) ion based on DNA-assisted amalgamation: a comparison study on gold, silver and Ag@Au Nanoplates

Naked-eye rapid recognition of tyrosine enantiomers using silver triangular nanoplates as colorimetric probe

Recognizing and quantifying enantiomers of chiral molecule is of great importance in chemical, biological and pharmaceutical fields. Herein, we presented one simple-yet-efficient method of sensing tyrosine (Tyr) enantiomers. In this sensing, silver triangular nanoplates (AgTNPs) were used as colorimetric probes. L-Tyr quickly induced the color of AgTNPs solution to change from dark blue to light gray, whereas D-Tyr induced no change of the AgTNPs solution color. The obvious color change enables the naked eye to recognize Tyr enantiomer. The visual method was used to detect the enantiometric excess value of L-Tyr in the whole range (-100 % ∼ 100 %). This chiral sensing can be finished within 5 min using one simple ultraviolet-visible spectrometer or naked eye. Furthermore, the mechanism of this chiral sensing was explored. It was confirmed that this chiral sensing was based on AgTNPs' intrinsic chirality. This chiral sensing is rapid, simple, and low-cost, and has great potential for chiral determination of Tyr.

A Review on Gold Nanotriangles: Synthesis, Self-Assembly and Their Applications

Gold nanoparticles (AuNPs) with interesting optical properties have attracted much attention in recent years. The synthesis and plasmonic properties of AuNPs with a controllable size and shape have been extensively investigated. Among these AuNPs, gold nanotriangles (AuNTs) exhibited unique optical and plasmonic properties due to their special triangular anisotropy. Indeed, AuNTs showed promising applications in optoelectronics, optical sensing, imaging and other fields. However, only few reviews about these applications have been reported. Herein, we comprehensively reviewed the synthesis and self-assembly of AuNTs and their applications in recent years. The preparation protocols of AuNTs are mainly categorized into chemical synthesis, biosynthesis and physical-stimulus-induced synthesis. The comparison between the advantages and disadvantages of various synthetic strategies are discussed. Furthermore, the specific surface modification of AuNTs and their self-assembly into different dimensional nano- or microstructures by various interparticle interactions are introduced. Based on the unique physical properties of AuNTs and their assemblies, the applications towards chemical biology and sensing were developed. Finally, the future development of AuNTs is prospected.

Rapid and highly selective colorimetric detection of mercury(II) ions in water sources based on a ribavirin functionalized AuNP sensor

Solvated mercuric ions (Hg²⁺), a toxic and harmful water pollutant, can easily accumulate in organisms and cause serious damage to the kidney, liver, and central nervous system. To realize rapid and efficient detection of mercury (II) ions in water sources, a kind of new colorimetric sensor of gold nanoparticles (AuNPs) functionalized with ribavirin (Rib-AuNPs) was proposed and characterized by TEM, DLS, XRD, and UV-vis in this work. The color of the Rib-AuNP solution rapidly changed from wine-red to gray-blue with the addition of Hg²⁺ based on the aggregation mechanism. The limits of detection (LODs) are 0.20 μM by the naked eye and 3.64 nM by UV-vis spectroscopy with a fine linear relationship in the range of 0-0.25 μM (R² = 0.9834) and 0.25-0.80 μM (R² = 0.9893) of Hg²⁺, indicating that the detection system of Rib-AuNPs could be applied to analyze Hg²⁺ with excellent selectivity and anti-interference in real water samples.

Capability of Au nano-rhombic dodecahedra in a label-free colorimetric assay: application in the determination of S2− and Hg2+

Au nano-rhombic dodecahedra  with high sensitivity to the environmental refractive index afford sensitive detection of S2- and Hg2+.

Application of DNA-Nanosensor for Environmental Monitoring: Recent Advances and Perspectives

PURPOSE OF REVIEW

Environmental pollutants are threat to human beings. Pollutants can lead to human health and environment hazards. The purpose of this review is to summarize the work done on detection of environmental pollutants using DNA nanosensors and challenges in the areas that can be focused for safe environment.

RECENT FINDINGS

Most of the DNA-based nanosensors designed so far use DNA as recognition element. ssDNA, dsDNA, complementary mismatched DNA, aptamers, and G-quadruplex DNA are commonly used as probes in nanosensors. More and more DNA sequences are being designed that can specifically detect various pollutants even simultaneously in complex milk, wastewater, soil, blood, tap water, river, and pond water samples. The feasibility of direct detection, ease of designing, and analysis makes DNA nanosensors fit for future point-of-care applications.

SUMMARY

DNA nanosensors are easy to design and have good sensitivity. DNA component and nanomaterials can be designed in a controlled manner to detect various environmental pollutants. This review identifies the recent advances in DNA nanosensor designing and opportunities available to design nanosensors for unexplored pathogens, antibiotics, pesticides, GMO, heavy metals, and other toxic pollutant.