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Enlargement of Gold Nanoparticles for Sensitive Immunochromatographic Diagnostics of Potato Brown Rot
摘要： Lateral ?ow immunoassay (LFIA) is a convenient tool for rapid ?eld-based control of various bacterial targets. However, for many applications, the detection limits obtained by LFIA are not suf?cient. In this paper, we propose enlarging gold nanoparticles’ (GNPs) size to develop a sensitive lateral ?ow immunoassay to detect Ralstonia solanacearum. This bacterium is a quarantine organism that causes potato brown rot. We fabricated lateral ?ow test strips using gold nanoparticles (17.4 ± 1.0 nm) as a label and their conjugates with antibodies speci?c to R. solanacearum. We proposed a signal enhancement in the test strips’ test zone due to the tetrachloroauric (III) anion reduction on the GNP surface, and the increase in size of the gold nanoparticles on the test strips was approximately up to 100 nm, as con?rmed by scanning electron microscopy. Overall, the gold enhancement approach decreased the detection limit of R. solanacearum by 33 times, to as low as 3 × 104 cells·mL–1 in the potato tuber extract. The achieved detection limit allows the diagnosis of latent infection in potato tubers. The developed approach based on gold enhancement does not complicate analyses and requires only 3 min. The developed assay together with the sample preparation and gold enlargement requires 15 min. Thus, the developed approach is promising for the development of lateral ?ow test strips and their subsequent introduction into diagnostic practice.
关键词： gold nanoparticles,immunochromatographic diagnostics,potato brown rot,gold particle growth,increase of sensitivity,lateral ?ow immunoassay,test strips,Ralstonia solanacearum
更新于2025-09-23 15:22:29
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Sensitive fluorescence sensor for point-of-care detection of trypsin using glutathione-stabilized gold nanoclusters
摘要： There is an urgent demand for on-site detection of biomarker, particularly in clinical diagnosis and therapeutics applications. Herein, we designed a convenient and sensitive fluorescence nanosensor for point-of-care determination of trypsin (TRY). The fluorescence intensity of gold nanoclusters (AuNCs) can be quenched by cytochrome c (Cyt c) via electron transfer mechanism. TRY specifically catalyzes the hydrolysis of Cyt c to produce small peptide fragments, inducing the significant fluorescence recovery. As a result, the AuNCs-based system processed a sensitive and selective response to TRY with the range 0.2-100 μg mL-1, accompanying a detection limit of 0.08 μg mL-1. Significantly, the sensing assay can be used to construct test strips for rapid and visual recognition of TRY. Combining with smartphone and ImageJ software, we further developed an image processing algorithm for quantitative detection of TRY with highly promising, which validated the potential point-of-care application.
关键词： Gold nanoclusters,Fluorescence,Electron transfer,Trypsin,Test strips
更新于2025-09-10 09:29:36
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A dual-responsive fluorescent probe for detection of fluoride ion and hydrazine based on test strips
摘要： Hydrazine (N2H4) and fluoride ion (F-) are regarded as environmental pollutants and potential carcinogens. A dual-functional fluorescent probe (probe 1) was developed for both F- and N2H4 with high selectivity and sensitivity. 1 was based on nucleophilic aromatic substitution reaction for N2H4 detection and selective cleavage of 4-nitrobenzenesulphonyl group for the determination of F-. The limits of detection of probe for F- and N2H4 were 77.82 nM and 29.34 nM, respectively, which are far below the threshold limit value (TLV) of United States Environmental Protection Agency (EPA). The home-made test strips of 1 provided the positive tool for F- and gaseous N2H4 in different system. And the confocal fluorescence images indicated that 1 can quantitatively detect N2H4 in living PC12 cells. Promisingly, 1 has great prospects for N2H4 imaging and determining in living system.
关键词： Living cells,Fluoride ion,Dual-functional fluorescent probe,Hydrazine,Home-made test strips
更新于2025-09-10 09:29:36
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A cyclometalated iridium(III) complex-based fluorescence probe for hypochlorite detection and its application by test strips
摘要： A new cyclometalated iridium(III) complex-based fluorescence probe (IrCN) for hypochlorite (ClO?) has been synthesized and characterized. The probe displayed nonfluorescent around 577 nm, while a 54-fold enhancement in fluorescence emission intensity was observed after the addition of ClO? due to the removal of C=N isomerization effect. Such “turn-on” fluorescence probe worked excellently in wide pH range (5–12) with short response time (< 20 s) and the detection limit was as low as 0.11 μM. In addition, IrCN exhibited high selectivity even in the presence of other competing species. Furthermore, IrCN was successfully integrated in towards ClO? fluorescent test strips for real-time detection of ClO?.
关键词： Fluorescence probe,Iridium(III) complex,Test strips,Hypochlorite
更新于2025-09-09 09:28:46
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Mix-&-Read Determination of Mercury(II) at Trace Levels with Hybrid Mesoporous Silica Materials Incorporating Fluorescent Probes by a Simple Mix-&-Load Technique
摘要： The synthesis, characterization, and application of mesoporous materials containing boron–dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia-aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self-quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several m-PAD strips yields a portable, cheap, quick, and easy-to-handle tool for trace HgII analysis in water.
关键词： dyes/pigments,mercury,fluorescence,mesoporous materials,test strips
更新于2025-09-09 09:28:46
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Responsive Upconversion Nanoprobe for Background‐Free Hypochlorous Acid Detection and Bioimaging
摘要： Responsive nanoprobes play an important role in bioassay and bioimaging, early diagnosis of diseases and treatment monitoring. Herein, a upconversional nanoparticle (UCNP)-based nanoprobe, Ru@UCNPs, for specific sensing and imaging of hypochlorous acid (HOCl) is reported. This Ru@UCNP nanoprobe consists of two functional components, i.e., NaYF4:Yb, Tm UCNPs that can convert near infrared light-to-visible light as the energy donor, and a HOCl-responsive ruthenium(II) complex [Ru(bpy)2(DNCH-bpy)](PF6)2 (Ru-DNPH) as the energy acceptor and also the upconversion luminescence (UCL) quencher. Within this luminescence resonance energy transfer nanoprobe system, the UCL OFF–ON emission is triggered specifically by HOCl. This triggering reaction enables the detection of HOCl in aqueous solution and biological systems. As an example of applications, the Ru@UCNPs nanoprobe is loaded onto test papers for semiquantitative HOCl detection without any interference from the background fluorescence. The application of Ru@UCNPs for background-free detection and visualization of HOCl in cells and mice is successfully demonstrated. This research has thus shown that Ru@UCNPs is a selective HOCl-responsive nanoprobe, providing a new way to detect HOCl and a new strategy to develop novel nanoprobes for in situ detection of various biomarkers in cells and early diagnosis of animal diseases.
关键词： imaging,nanoprobes,paper-based test strips,bioassay and bioimaging,luminescence resonance energy transfer,selective HOCl detection and imaging
更新于2025-09-04 15:30:14