Color Reaction Research Articles

Phytochemical and biological screening of Lantana camara linn. leaves extract

The current study evaluated the phytochemical and biological screening of Lantana camara (Verbenaceae). It is a highly invasive ornamental garden plant species, native to tropical and sub-tropical America. Leaves of L. camara were extracted successively by petroleum ether and methanol by continuous hot percolation. The phytochemical screening was carried out by color reaction with different reagents. The Well diffusion method on Mueller Hinton agar was used for evaluating antimicrobial activity. The LD50 value was determined by acute toxicity studies. The analgesic activity was carried out by tail immersion method, antimotility activity was carried out by charcoal movement test and the antidiabetic activity was carried out by oral glucose tolerance test. The extractive value of methanolic and petroleum ether was found to be 10.11% and 3.11% respectively. The preliminary phytochemical screening showed a positive reaction test for glycoside, tannin, saponin, steroid, flavonoid, carbohydrates, diterpene, and triterpene. The extract showed significant antimicrobial activity against S. aureus (p<0.05) and didn't show any activity against E. coli. The LD50 value was found above 2000mg/kg. The analgesic, antimotility and antidiabetic activity of plant extract showed significant results in a dose-dependent manner (p<0.05). The study revealed that the plant possessed antibacterial, analgesic, antimotility and antidiabetic activity. Further studies are needed to standardize the extract and evaluation of the safety profile in long-term toxicity studies is recommended

Comparative Phytochemical Analysis and Antiradical Activity of Five Plants Used for the Treatment of Type 2 Diabetes in Benin

Background: Diabetes remains a real public health problem in the world today. Although considered a disease of rich countries, today diabetes is increasingly a major concern in developing countries and particularly in sub-Saharan Africa. In Benin, its prevalence in 2015 was 12.4%.
 Objective: This work aimed to compare the secondary metabolites, the content of phenolic compounds (total phenol, flavonoid) and the antiradical power of five plants (Bambusa vulgaris Schrad. Ex Wendel; Parkia biglobosa (Jacq.) R. Br. Ex G. Don; Mangifera indica L.; Saccharum officinarum L.; and Annona muricata L.) used in Benin by traditional healers to treat type 2 diabetes.
 Materials and Methods: Secondary metabolites were identified by coloration and precipitation reactions specific to each family of metabolites. Total phenols were determined by Folin Ciocalteu method. The aluminum trichloride method has been used to quantify total flavonoids. The antiradical capacity was evaluated by 2,2-diphenyl-l-picrylhydrazyl (DPPH).
 Results: Plants which leaves were higher in total phenols were Mangifera indica, Parkia biglobosa and Bambusa vulgaris while Annona muricata and Parkia biglobosa were the richest plants in flavonoids. The hydroethanolic extract of leaves of Bambusa vulgaris (IC50=0.28mg/mL), Parkia biglobosa (IC50=0.3mg/mL) and Mangifera indica (IC50=2.5mg/mL) showed more pronounced antiradical activity than vitamin C (IC50=3.2 mg/mL) which were synthetic antioxidant.
 Conclusion: Our results showed that among the five plants studied Mangifera indica, Parkia biglobosa and Bambusa vulgaris were the richest in total phenols and also those whose leaf extracts had the highest antiradical activities. These three plants could therefore be considered as potential remedies for type 2 diabetes and its complications.

Anti-inflammatory effect of polyherbal composition with hepatoprotective and choleretic properties on LPS-stimulated murine macrophages.

A polyherbal formulation with hepatoprotective and choleretic properties combining pharmacological potential of eight medicinal plants was developed in Nargiz Medical center (Republic of Azerbaijan) for the use as herbal tea. To explore the effect of polyherbal composition on the metabolism of LPS-stimulated macrophages in vitro. The qualitative and quantitative phytochemical analysis was conducted using specific color reactions and gas chromatography-mass spectrometry (GC-MS). Nitric oxide (NO) assay was determined using the Griess reaction. Reactive oxygen species (ROS) generation was measured using ROS-sensitive fluorescence indicator, H2DCFDA, by flow cytometry. Arginase activity was examined by colorimetric method. The studied polyherbal formulation exerted anti-inflammatory activity in LPS-stimulated macrophages which was evidenced by dose-dependent decrease of ROS generation and by shift of arginine metabolism to the increase of arginase activity and decrease of NO release. Our findings suggest that the herbal tea reduces macrophage inflammatory activity, that provide an important rationale to utilize it for the attenuation of chronic inflammation typical of hepatobiliary disorders.

Smartphone recognition-based immune microparticles for rapid on-site visual data-sharing detection of Newcastle disease virus

Since the last century, animal viruses have posed great threats to the health of humans and the farming industry. Therefore, virus control is of great urgency, and regular, timely, and accurate detection is essential to it. Here, we designed a rapid on-site visual data-sharing detection method for the Newcastle disease virus with smartphone recognition-based immune microparticles. The detection method we developed includes three major modules: preparation of virus detection vectors, sample detection, and smartphone image analysis with data upload. First, the hydrogel microparticles containing active carboxyl were manufactured, which coated nucleocapsid protein of NDV. Then, HRP enzyme-labeled anti-NP nanobody was used to compete with the NDV antibody in the serum for color reaction. Then the rough detection results were visible to the human eyes according to the different shades of color of the hydrogel microparticles. Next, the smartphone application was used to analyze the image to determine the accurate detection results according to the gray value of the hydrogel microparticles. Meanwhile, the result was automatically uploaded to the homemade cloud system. The total detection time was less than 50 min, even without trained personnel, which is shorter than conventional detection methods. According to experimental results, this detection method has high sensitivity and accuracy. And especially, it uploads the detection information via a cloud platform to realize data sharing, which plays an early warning function. We anticipate that this rapid on-site visual data-sharing detection method can promote the development of virus self-checking at home.

Effects of Maternal Nicotine Exposure on Fibronectin Expression in the Kidney of Mouse Newborns in Embryonic and Milking Period

Background: Tobacco use in various forms, including hookah, has increased in recent years, especially among young people, who are the group of reproductive age. In the present study, the effect of nicotine on fibronectin expression as a component of basement membrane and extracellular matrix was evaluated in the kidney tissue of neonates whose mothers were exposed to cigarette smoke during pregnancy and lactation period. Methods: Fibronectin expression on days 1, 7, 14, and 21 after delivery was evaluated in the kidneys of Balb/C mice neonates whose mothers were exposed to cigarette smoking during pregnancy and lactation periods. Immunohistochemical and real-time PCR evaluations were performed, and a comparison was made with the control groups. In the experimental groups, nicotine dissolved in saline was injected subcutaneously at a dose of 2 mg/kg daily until the desired day. Results: Our results demonstrated that the expression level of fibronectin increased in nicotine-administrated newborns compared to the healthy controls on days 1 (P = 0.043) and 7 (P = 0.008). The intensity of color reaction on days 1 and 7 was significantly higher in the main kidney structures, including glomeruli and proximal and distal convoluted tubules, in the experimental group than in the control group. The maximum fibronectin expression level was observed on day 7 in the experimental group in comparison with the control group. Conclusions: Nicotine may decrease glomerular filtration rate by increasing fibronectin expression in the basement membrane and extracellular matrix, thereby justifying renal failure in infants exposed to nicotine during embryonic and lactation periods.

Effects of monosaccharide composition on quantitative analysis of total sugar content by phenol-sulfuric acid method

Phenol-sulfuric acid method is one of the most common methods applied to the analysis of total sugar content during polysaccharides study. However, it was found that the results obtained from the phenol-sulfuric acid method was generally lower than the real total sugar content, especially when acidic monosaccharides were contained in the polysaccharides samples. Therefore, the present study focused to unveil the proposed problem. Based on the optimization of colorimetric conditions, such as optimal wave length of absorption, linearity range, color reaction time and temperature, it indicated that the phenol-sulfuric acid method was a convenient and accurate way for the total sugar content analysis. In addition, the color-rendering capabilities of 10 common monosaccharides were systematically analyzed to obtain a relative correction factor for each monosaccharide relative to glucose, which was proved to be the main reason for the deviation in the detection of total sugar content. Moreover, the key points during the application of phenol-sulfuric acid method were suggested. This study provides a scientific theoretical basis and a reliable experimental research method for the accurate determination of total sugar content by the phenol-sulfuric acid method, and which will also promote the application of this convenient method in the polysaccharides study.

A colorimetric/electrochemical dual-mode sensor based on Fe3O4@MoS2-Au NPs for high-sensitivity detection of hydrogen peroxide

Hydrogen peroxide (H2O2) is closely related to many diseases and is often used as a target for disease diagnosis and treatment, so the research of H2O2 detection method has attracted much attention. Compared with the current single-signal detection methods commonly used, dual-mode detection has inherent self-verification and self-correction functions and is expected to provide more reliable and anti-interference detection results. In this work, a novel nanocomposite Fe3O4@MoS2-Au NPs with strong peroxidase activity was constructed for the first time, and on this basis, a colorimetric/electrochemical dual-mode sensor was successfully prepared. Concretely, the Fe3O4@MoS2-Au NPs could catalyze reduction of H2O2 to generate ·OH, leading to a significant electrochemical signal. At the same time, the color reaction of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) by ·OH can be used to build a colorimetric sensor. In colorimetric and electrochemical sensing systems, the linear range was 1–120 μM. The detection limit (LOD) can reach as low as 109 nM and 80 nM, respectively. In addition, the sensor has been favorably used for the detection of H2O2 in normal human serum, and the recovery range was 87.55–113.13 %. In conclusion, this work provides an economical, sensitive and visualized H2O2 detection platform, which has a wide application prospects.

Use of dimethylglyoxime for the spectrophotometric flow-based determination of nickel in natural waters

A spectrophotometric flow-based method for the determination of nickel in recreational waters is proposed. In this scenario, the strategy was to devise a miniaturized and automatic system based on sequential injection analysis, aiming for an expeditious, real-time and low-cost determination. For the spectrophotometric determination, dimethylglyoxime was used as color reagent due to its selectivity for nickel. Considering the expected low concentration and low sensitivity of the coloured reaction, a long pathlength flow cell was used to increase the sensitivity. The potential interference of metal ions commonly present in freshwaters was assessed and no significant differences (<10%) were observed, except for manganese. This interference was overcome by adding manganese to the reagent, thus acting as a fixed interference strategy. The limit of detection and quantification were 6.3 and 21.1 µg L−1, respectively. The method was applied to the quantification of nickel in certified water samples and the results were in agreement with the certified values. Additionally, the method was successfully applied to the quantification of nickel in spiked freshwaters and the results were in agreement with those obtained with the reference method.

Design of a microfluidic paper-based device for the quantification of phenolic compounds in wine samples

In this work, the design and development of a microfluidic paper-based device (μPAD) for the quantification of total phenolic compounds (TPC) in wines is described. The developed μPAD was based upon the vertical flow concept and the colour reaction used was the known Folin-Ciocalteu reaction using gallic acid as reference phenolic compound. After studying operational parameters, namely type of paper, reagents and sample volume, a dynamic range of 5–50 mg L−1 was obtained with a limit of detection of 1.2 mg L−1. The described device proved to have good precision (relative standard deviation < 5%) and no significant interferences were observed from known compounds present in wines. Furthermore, the stability of the colour product and of the device itself were assessed; the μPAD was stable for 30 days (in the dark at room temperature) and it could be scanned up to 8 h after sample introduction. The developed μPAD pose as a simple method for TPC quantification and was successfully applied to several wine samples including sparkling and table wines with two different approaches: i) using gallic acid as reference compound with standard addition; and ii) using taniraisin with external calibration. The accuracy of the proposed μPAD method was assessed by comparison with the reference spectrophotometric method according to the International Organisation of Vine and Wine (OIV) recommendations.

Ultrasensitive colorimetric detection of Hg2+ based on glutathione-modified Au nanoflowers

Due to the harm of metal mercury to the environment and the human body, there is an urgent need for exploring novel, simple, and reliable methods for the detection of Hg2+. Herein, a colorimetric method is proposed for the determination of Hg2+ based on the analyte inducing the aggregation of Glutathione-modified gold nanoflowers (GSH-Au NFs) with activated peroxidase-mimicking activity. Briefly, highly dispersed GSH-Au NFs show negligible enzyme-like activity in water. When Hg2+ is added, GSH-Au NFs would aggregate rapidly for the interaction of Hg2+ with the carboxyl and amine groups of GSH. And the aggregates exhibit high peroxidase-mimicking catalytic activity and can catalyze the color reaction of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H2O2. Based on these phenomena, an ultrasensitive colorimetric detection method of Hg2+ has been developed. The linear range of this method is 10–300 nM and the detection limit is down to 3.9 nM, which is much lower than the standard value specified by the US EPA. The accuracy of the method has been verified in water samples, which reveals its great potential in environmental monitoring.

Non-Destructive Scientific Analysis of the Gold Fabric Excavated of Cheongsong Shim’s Grave

Using non-destructive analytical methods, we identified the material characteristics of two gold fabric artifacts excavated from the Cheongsong Sim clan (Bugeum Wonsam, Jikgeum Chima), including the artifact condition, fiber type, surface contamination, and metallic threads. We found that the artifacts were buried and had turned brown; thus, we were unable to determine their original color. The fiber type was determined to be silk from cocoons, based on scanning electron microscopy, Fourier transform infrared (FT-IR) analyses of Amide I, II, III, and IV peaks, and color reactions Further, the FT-IR and X-ray fluorescence (XRF) analyses identified the white and black stains as natural resin hydrolyzed substances, such as lipids and proteins, that occurred as microbial decomposition due to body decay. Finally, the XRF analyses identified the thin gold layer of the metallic yarn as gold (Au). According to the FT-IR data and the color reaction to the metallic yarn medium, the adhesive component of the medium was a product of-Amides I, II, III, and 3000 cm-1 within Amides A and B (an animal type), respectively. Thus, the medium was identified as Hanji (Korean paper), which is made from domestically produced Broussonetia kazinoki fibers.

ИССЛЕДОВАНИЯ ПО СОЗДАНИЮ КОМБИНИРОВАННОГО ЛЕКАРСТВЕННОГО СРЕДСТВА АНТИОКСИДАНТНОГО ДЕЙСТВИЯ

Abstract. Currently, the search and creation of antioxidant drugs has high relevance and practical significance. From this point of view, drugs such as taurine and ascorbic acid, dihydroquercetin are of interest, which are important in regulating the antioxidant system. The proposed drug will allow correcting oxidative processes, the immune state of the body, improve all metabolic processes, eliminate all free radicals that are formed in the process of vital activity. The proposed composition (taurine, ascorbic acid, dihydroquercetin) is essential in maintaining and stabilizing the body's antioxidant protection in the prevention and treatment of various diseases, including viral diseases, which are characterized by an increase in free radical processes and in the depletion of the body's natural antioxidant protection. To assess the antioxidant drug market and the practical significance of the development of an effective antioxidant drug, marketing studies have been conducted that have confirmed the relevance of the planned studies. Based on the results of studies of the literature data, the composition and dosage of the proposed antioxidant drug, including taurine, ascorbic acid, dihydroquercitin and auxiliary substances in the form of powder, is justified. To identify the ingredients of the developed antioxidant drug, qualitative color reactions are proposed that are sensitive and specific. Quantitative determination is proposed to be carried out by spectral (taurine, dihydroquercetin) and titrimetric (iodatometric) methods (ascorbic acid). The assay methods for the ingredients are validated (specific, sensitive and linear). Based on the results of experimental studies, the quality standards of the proposed antioxidant drug have been developed.

Structural and interactions analysis of a transcription factor PnMYB2 in Panax notoginseng

The main active ingredients of the traditional Chinese medicinal plant, Panax notoginseng, are the Panax notoginseng saponins (PNS). They can be synthesized via the mevalonate pathway; PnSS and PnSE1 are the key rate-limiting enzymes in this pathway. In this study, an interaction between PnMYB2 and the key enzymes was identified and characterized from the P. notoginseng cDNA library using the Y1H technique. Subsequently, X-α-gal color reaction confirmed the interaction between PnMYB2 and the upstream sequences of PnSS and PnSE1 promoters. Full-length cDNA sequence of PnMYB2 was isolated and characterized. PnMYB2 has an open reading frame of 864 bp, encoding 287 amino acids. 3D structural analysis of PnMYB2 indicated that its structure was similar to that of the template. Phylogenetic analysis revealed that PnMYB2 and PgMYB2 are highly homologous and belong to the R2R3 MYB transcription factor (TF). Subcellular localization analysis showed that PnMYB2 was localized in the nucleus. The recombinant protein PnMYB2 was successfully obtained through prokaryotic expression and was confirmed to be an inclusion body protein. Furthermore, electrophoretic mobility shift assay (EMSA) experiments demonstrated that PnMYB2 specifically binds to MYB core and AC-rich elements. This study provides a theoretical basis for transcriptional regulation of saponin biosynthesis in P. notoginseng.

A Simple Counting-Based Measurement for Paper Analytical Devices and Their Application.

This work introduces the concept of a counting-based measurement on paper analytical devices (cPADs) to improve the utilization of numerous reactions. The design of cPADs consists of two layers of paper substrates; the first layer contains a central sample zone combined with a radial surrounded by 12 detection zones that are predeposited with the various reagents, and the second layer acts as a connection channel between the sample zone and each detection zone. The solution can vertically flow from the first to the second layer and then move through the area to each subsequent detection zone. The analyte level can be evaluated by counting the number of detection zones that change color from a blank signal. Furthermore, our cPADs exhibit a capability of implementation for a broad series of reactions. Compared to the dPAD technique, some reactions that are possibly difficult to apply in such devices can be wholly enabled in our devices. The final color reaction on cPADs can apparently occur due to its identity. We applied this technique to the monitoring of carbaryl (CBR) and copper ions (Cu2+) using different reactions, including azo-coupling and complexation, respectively. Accordingly, this indicates an excellent result validated using the more traditional methods. Our cPADs can be applied for rapid screening of both CBR and Cu2+ in water samples with outstanding accuracy and precision using a naked-eye measurement by a relatively unskilled person. We offer a simple platform on PADs for rapid screening, combining high cost-effectiveness within a miniaturized platform designed for use with onsite applications, which is thus suitable for several different reactions.

RuO2/rGO heterostructures as mimic peroxidases for colorimetric detection of glucose.

Thesuccessful synthesis of ruthenium oxide/reduced graphene oxide (RuO2/rGO) heterostructures by one-pot hydrothermal method using graphene oxides and RuCl3 as precursorsis reported. The heterostructures had high peroxidase-like (POD-like) activities, which catalyzes the oxidation of classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to create a blue colored reaction product. The catalytic activity was significantly enhanced by the synergistic effect between RuO2 nanoparticles and rGO. RuO2/rGO had a low Km of 0.068mM and a high vmax of 1.228 × 10-7 M·s-1 towards TMB in theTMB-H2O2 catalytic oxidation system. In addition, the POD-like activity originating from the electron transfer mechanism was confirmed by cytochrome C (Cyt C) oxidation experiment. A colorimetric method based on RuO2/rGO heterostructures was developed with good sensitivity and selectivity for glucose detection with a limit of detection of 3.34μM and a linear range of 0-1500μM. The RuO2/rGO heterostructures havepotential applications in the biomedical areas, such as biosensor and diagnostics.

Phenol colour reaction and its biochemical basis in cultivated wheat genotypes

For seed to play a catalytic role, it should reach farmers in a good quality state, i.e. high genetic purity and identity. So, varietal purity testing plays a critical role in preventing varietal admixtures. Phenol colour reaction is being used as a rapid varietal identification technique for a long time. PPO has been implicated to cause this enzymatic browning. Polyphenol oxidase activity (PPO) must be reduced or eliminated if wheat quality is to be improved. This research was undertaken for development of quick genetic purity testing method in wheat varieties and to study the effect of PPO activity during storage in cultivated wheat. The biochemical studies of the pathway which gives phenol colouration has also been studied.

Old dogs, new trick: Classical starch˗sodium iodide reagent as the chromogenic substrate of peroxidase-like nanozymes

2, 2′-azinobis-3-ethylbenzthiazoline-6-sulfonate (ABTS), 3, 3′, 5, 5′-tetramethylbenzidine (TMB), o-phenylenediamine (OPD) are typical chromogenic substrates to evaluate the activity of peroxidase-like nanozymes. However, these substrates are toxic, unstable, and the coloration reactions are slow. Herein, the classical starch-sodium iodide reagent was utilized as the chromogenic substrate to evaluate peroxidase-like activity of nanozymes. Starch-sodium iodine is less toxic, more stable and faster color reaction than ABTS, TMB and OPD. Under the catalysis of peroxidase-like nanozymes such as Mo5N6 nanosheets, graphene oxide nanosheets, Fe3O4 nanoparticles, CeO2 nanoparticles, iodide ion (I–) is oxidized by H2O2 to produce blue color complex (starch-I2). Taking Mo5N6 nanosheets as the peroxidase-like nanozyme, the color reaction completed within 5 min at room temperature (25 ºC), and the chromogenic substrate remained stable within 30 days. The maximum reaction rate (Vmax) using starch-sodium iodine as the chromogenic substrate was more than 100-fold higher than that of TMB. Based on this, a sensitive colorimetric sensor and facile portable agarose gel test kits were proposed and applied for the detection of H2O2 residue in liquid milk samples with fast response.

A Wearable Electrowetting on Dielectrics Sensor for Real‐Time Human Sweat Monitor by Triboelectric Field Regulation

AbstractWearable sweat sensors can analyze the abundant composition of solutes and metabolites in sweat to reflect the health state of the wearers in real time. The realization of active motion control for sweat droplets is significant for a multifunctional sweat monitoring device with several analysis chambers. Here, a wearable droplet‐based human sweat monitoring platform (WSMP), by combining an electrowetting on dielectrics (EWOD) device and a triboelectric nanogenerator (TENG), is demonstrated. It allows to collect and transport sweat droplets in different chambers by dielectric wetting effect and eventually merge and react with a pH indicator. The mechanical and electrical model of WSMP is introduced to describe the relationship between the open‐circuit voltage of the TENG and the voltage applied on the EWOD device. The high‐voltage electrical field generated by the TENG can change the wettability of solid–liquid interfaces and realize the controlling of droplet motion. The contact angle of electrolyte droplets changes over 30% with the triboelectric voltage of 5 kV. The driving, merging, and color reaction can be realized by actively controlling the motion of droplets. Finally, a wearable WSMP worn on the shank successfully demonstrates the preliminary detection of the pH level of human sweat.

Histochemical study of the hepatic metacestodes in sheep infected with hydatidosis

This study aimed at detecting the liver histopathological changes of hydatid cysts sheep infestation. Seventeen sheep liver's samples, infested with hydatid cysts, were collected from the local butchers. The specimens sectioned, processed, and stained with hematoxylin and eosin and some special stains such as Gomori's aldehyde fuschin, Van Gieson, Toluidine blue, Alcian blue, Periodic Acid Schiff (PAS) and Mansso's trichrome. The results of haematoxylin and eosin stain of infected groups revealed the presence of the laminated membrane of hydatid cyst in different spots of hepatic tissue encircled by infiltration of inflammatory cells, an increase in fibrous tissue and severe necrotic hepatic tissue. The special stains as in Gomori's aldehyde fuschin revealed the protoscolex in green colour and elastic fibres of connective tissue surrounding hydatid cyst with its laminated membrane in purple colour. Van Gieson stain showed dark brown-purple colour of the elastic fibres reduplication of connective tissue surrounding hydatid cyst, while Toluidine blue stain sections revealed the dark blue stain of acidic components of hydatid cyst laminated membrane and necrotic hepatocytes. Alcian blue stain revealed the blue colour reactivity of the proteoglycans of the connective tissue surrounding hydatid cyst. PAS reaction stain revealed the magenta colour reaction of the intact hepatocytes in the control group comparing with depletion of magenta colour in necrotic hepatocytes surrounding hydatid cyst. Masson's trichrome stain revealed increased collagen fibres of the connective tissue. At the conclusion, it’s evident that infection with hydatid cysts causes a variety of histopathological alterations that appeared through several tissue stains.

Colorimetric copper (Ⅱ) ions detection in aqueous solution based on the system of 3′3′5′5′-tetramethylbenzidine and AgNPs in the presence of Na2S2O3

Herein, a colorimetric copper (Ⅱ) ion (Cu 2+ ) detection system based on the oxidization reaction of 3′3′5′5′-tetramethylbenzidine (TMB) and Ag(S 2 O 3 ) 2 3− (in aqueous solution) was designed. The detection system comprised TMB, silver nanoparticles (AgNPs) and thiosulfate (S 2 O 3 2− ). It was observed that AgNPs were unable to oxidize TMB to a blue color. While, Cu 2+ ions could effectively catalyze the S 2 O 3 2- -leaching system, thereby converting AgNPs to Ag(S 2 O 3 ) 2 3− . Similar to Ag (I), Ag(S 2 O 3 ) 2 3− catalyzed the color reaction of TMB. The colorimetric copper (Ⅱ) ion (Cu 2+ ) detection system was fabricated. Results showed that the optimal amounts of TMB and Na 2 S 2 O 3 were 800 and 400 μM, respectively, and the reaction time and temperature were 40 min and 25 °C, respectively. The range of curvature tendency was 1–100 μM, with a limit of detection of 100 nM. The detection system exhibited a high selectiveness for copper ions in an aqueous solution. Furthermore, this system shows remarkable promise for monitoring the aqueous quality.