Fluorimetric Mercury Test Strips with Suppressed “Coffee Stains” by a Bio-inspired Fabrication Strategy

Abstract

A fluorimetric Hg2+ test strip has been developed using a lotus-inspired fabrication method for suppressing the “coffee stains” toward the uniform distribution of probe materials through creating a hydrophobic drying pattern for fast solvent evaporation. The test strips were first loaded with the model probes of fluorescent gold-silver nanoclusters and then dried in vacuum on the hydrophobic pattern. On the one hand, here, the hydrophobic constraining forces from the lotus surface-like pattern could control the exterior transport of dispersed nanoclusters on strips leading to the minimized “coffee stains”. On the other hand, the vacuum-aided fast solvent evaporation could boost the interior Marangoni flow of probe materials on strips to expect the further improved probe distribution on strips. High aqueous stability and enhanced fluorescence of probes on test strips were realized by the hydrophilic treatment with amine-derivatized silicane. A test strips-based fluorimetry has thereby been developed for probing Hg2+ ions in wastewater, showing the detection performances comparable to the classic instrumental analysis ones. Such a facile and efficient fabrication route for the bio-inspired suppression of “coffee stains” on test strips may expand the scope of applications of test strips-based “point-of-care” analysis methods or detection devices in the biomedical and environmental fields.

High-Throughput and Sensitive Fluorimetric Strategy for MicroRNAs in Blood Using Wettable Microwells Array and Silver Nanoclusters with Red Fluorescence Enhanced by Metal Organic Frameworks

“…After spoting with hydrophilic PAA, it could be decreased to about 38°. Once the glass slide was further patterned with hydrophobic HDS, the maximal CA of about 123° would be achieved, which would endow the arrays with antifouling effect. , Moreover, the etching of PAA microdots with NaOH would reduce the average CA of the microwells substrates down to about 54°. Interestingly, once the microwells were deposited with APTES, the resulted hydrophilic substrates could display a minimum CA of about 31°.…”

“…​It can be seen that the microwells were formed with pretty high density on the hydrophobic substrates (top), of which the substrate surfaces were furnitured with numerous particles as revealed in the topologically magnified image (bottom)​. Notably, such a wettable profile of the microwells arrays could provide a self-cleaning interface between the testing microdots so as to avoid any in-between fouling or crossing contamination of the sample droplets. , As a result, the construction of denser microwells array could be expected for the high-throughput and selective analysis of targeting miRNAs within a single experiment.…”

“…Notably, such a wettable profile of the microwells arrays could provide a self-cleaning interface between the testing microdots so as to avoid any in-between fouling or crossing contamination of the sample droplets. 53,54 As a result, the construction of denser microwells array could be expected for the high-throughput and selective analysis of targeting miRNAs within a single experiment.…”

Label-Free Cross-Priming Amplification Coupled With Endonuclease Restriction and Nanoparticles-Based Biosensor for Simultaneous Detection of Nucleic Acids and Prevention of Carryover Contamination

“…These disadvantages shared by traditional monitoring techniques have spurred the researchers to devise other superior analysis technique. Accordingly, lateral flow biosensor (LFB) has been developed for solving such shortcomings above, due to the excellent traits of visual results interpretation, pollution-free, user-friendly, reliable, and rapid signal output in low-resource settings (Qiao et al, 2016; Huo et al, 2017; Gou et al, 2018; Meng et al, 2018). In this report, we established a novel label-free CPA-LFB method to construct the double-labeled detectable CPA amplicons, which could be detected by LFB.…”

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

“…For example, He et al successfully developed an ultrasensitive nucleic acid biosensor based on HRP–AuNP dual labels and a lateral flow strip biosensor [ 35 ]. Qiao et al developed a fluorometric Hg 2+ test strip using Au–Ag nanoclusters as fluorescent probes combined with suppressing “coffee stains” by a bio-inspired fabrication strategy [ 36 ]. Zhang et al used Cy5-labeled functional ssDNA toward multiple analytes, graphene oxide, and paper substrate to fabricate a paper device to report the presence of the Hg 2+ and Ag + ions and aminoglycoside antibiotics in food [ 37 ].…”