Magnetically separable and recyclable bamboo-like carbon nanotube-based FRET assay for sensitive and selective detection of Hg2

Captivating nano sensors for mercury detection: a promising approach for monitoring of toxic mercury in environmental samples

Mercury, a widespread highly toxic environmental pollutant, poses significant risks to both human health and ecosystems. It commonly infiltrates the food chain, particularly through fish, and water resources via multiple pathways, leading to adverse impacts on human health and the environment. To monitor and keep track of mercury ion levels various methods traditionally have been employed. However, conventional detection techniques are often hindered by limitations. In response to challenges, nano-sensors, capitalizing on the distinctive properties of nanomaterials, emerge as a promising solution. This comprehensive review provides insight into the extensive spectrum of nano-sensor development for mercury detection. It encompasses various types of nanomaterials such as silver, gold, silica, magnetic, quantum dot, carbon dot, and electrochemical variants, elucidating their sensing mechanisms and fabrication. The aim of this review is to offer an in-depth exploration to researchers, technologists, and the scientific community, and understanding of the evolving landscape in nano-sensor development for mercury sensing. Ultimately, this review aims to encourage innovation in the pursuit of efficient and reliable solutions for mercury detection, thereby contributing to advancements in environmental protection and public health.

Nanotechnology-based analytical techniques for the detection of contaminants in aquatic products

Food safety of aquatic products has attracted considerable attention worldwide. Although a series of conventional bioassays and instrumental methods have been developed for the detection of pathogenic bacteria, heavy metal residues, marine toxins, and biogenic amines during the production and storage of fish, shrimp, crabs et al., the nanotechnology-based analyses still have their advantages and are promising since they are cost-efficient, highly sensitive and selective, easy to conduct, facial design, often require no sophisticated instruments but with excellent detection performance. This review aims to summarize the advances of various biosensing strategies for bacteria, metal ions, and small molecule contaminants in aquatic products during the last five years, The review highlights the development in nanotechnologies applied for biorecognition process, signal transduction and amplification methods in each novel approach, the nuclease-mediated DNA amplification, nanomaterials (noble metal nanoparticle, metal-organic frameworks, carbon dots), lateral flow-based biosensor, surface-enhanced Raman scattering, microfluidic chip, and molecular imprinting technologies were especially emphasized. Moreover, this study provides a view of current accomplishments, challenges, and future development directions of nanotechnology in aquatic product safety evaluation.

Colorimetric detections of iodide and mercuric ions based on a regulation of an Enzyme-Like activity from gold nanoclusters

A simple colorimetric method was developed for sensitive and selective detections of I^- and Hg²⁺. Histidine stabilized gold nanoclusters (His-AuNCs) were synthesized and catalyzed the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to a blue product. As a strong ligand toward gold, iodide (I^-) attached to the surface of the His-AuNCs and significantly enhanced the oxidase-like activity of the His-AuNCs. Based on this enhancement, a sensitive colorimetric response toward I^- was obtained. Furthermore, the strong interaction between Hg²⁺ and I^- was adopted for an indirect Hg²⁺ detection. Under the optimal conditions, the platform presented high selectivity for the determinations of I^- and Hg²⁺ in the ranges 0.02-1 µM and 0.05-0.8 µM, with detection limits as 3.3 nM and 8 nM respectively. This colorimetric assay was successfully applied for analysis of real samples.

Nanozymes-Hitting the Biosensing "Target"

Nanozymes are a class of artificial enzymes that have dimensions in the nanometer range and can be composed of simple metal and metal oxide nanoparticles, metal nanoclusters, dots (both quantum and carbon), nanotubes, nanowires, or multiple metal-organic frameworks (MOFs). They exhibit excellent catalytic activities with low cost, high operational robustness, and a stable shelf-life. More importantly, they are amenable to modifications that can change their surface structures and increase the range of their applications. There are three main classes of nanozymes including the peroxidase-like, the oxidase-like, and the antioxidant nanozymes. Each of these classes catalyzes a specific group of reactions. With the development of nanoscience and nanotechnology, the variety of applications for nanozymes in diverse fields has expanded dramatically, with the most popular applications in biosensing. Nanozyme-based novel biosensors have been designed to detect ions, small molecules, nucleic acids, proteins, and cancer cells. The current review focuses on the catalytic mechanism of nanozymes, their application in biosensing, and the identification of future directions for the field.

Chemogenetic biocompatibly of mercury as specific hypercalcemia actuator in neuronal spinal cord cell manipulation: Zeta bio-sensing analysis

Chemogenetic property of mercuric ion (Hg²⁺) was investigated as a specific hypercalcemia actuator in the neuronal spinal cord cell manipulation by Zeta-based potentiometric bio-sensing analysis via introducing a novel array-based Hg²⁺ bio-sensor. For this purpose, the array of a two-electrode system including Ag/AgCl (sat'd Cl^-) as reference electrode and a paste nano-composite as the indicator electrode was utilized. The indicator electrode was made of activated multi-walled carbon nanotubes as conductive support, a grounded slice of sheep's spinal cord as natural neuron stem cells (ionophore), and oxalate ion as both the dispersed phase and cationic site. Under optimum conditions by one-at-a-time method, a two-linear range between 1.3 × 10^-4- 6.5 × 10^-12 and 2.7 × 10^-14- 1.4 × 10^-21 mol L^-1 with correlation coefficients (R²) of 0.96 and 0.99, respectively, and response time (t₉₀) of maximum 5.0 min were approximated. The percentages of relative standard deviation were estimated to be 4.05 (repeatability, n = 10) and 6.14 (reproducibility, n = 12). The detection limit was estimated to be sub 5.3 × 10^-22 mol L^-1 based on the X̄_b+3S_b. The reliability of this phenomenon was evidenced by different analytical techniques. The Zeta-based electrical response was therefore attributed to highly Ca²⁺ pumping from the stem cells ionic channel gates as the proposed mechanistic behavior of the spinal cord. Actuating (triggering) the stem cells by Hg²⁺ consequently led to generate significant Zeta potential as the proposed mechanism. The results pointed to the potentiometric responsibility of a protein with gram molecular weight of 66.2 ± 0.3 KCU in the stem cell matrix as a specific hypercalcemia actuator.

FRET-based fluorescent probe for drug assay from amino acid@gold-carbon nanoparticles

Biocompatible and luminescent nanostructures synthesized by capping gold-carbon nanoparticles (HOOC-4-C₆H₄-AuNPs) with amino acids tyrosine, tryptophan, and cysteine were used for the quantitative estimation of ranitidine (RNH), a peptic ulcer and gastroesophageal reflux drug. We applied a fluorescence quenching mechanism to investigate the viability of the energy transfer based on gold-carbon nanosensors. Förster resonance energy transfer (FRET) calculations showed a donor-acceptor distance of 1.69 nm (Tyr@AuNPs), 2.27 nm (Trp@AuNPs), and 2.32 nm (Cys@AuNPs). The constant time-resolved fluorescence lifetime measurements supported the static quenching nature. This method was successfully utilized in the detection and quantification of RNH, with a limit of detection (LOD) of 0.174, 0.56, and 0.332 μM for Tyr@AuNP, Trp@AuNP, and Cys@AuNP bioconjugates, respectively. This approach was also successful in the quantification of RNH in spiked serum samples.