Viruses In Water Research Articles

Inactivation of MS-2 virus in water by rotational generator of hydraulic shock

This study investigates the effect of hydraulic shock waves on inactivation of MS-2 bacteriophage, a norovirus surrogate. A falling circular jet of water spiked with the MS-2 (∼1000 PFU/mL) was repeatedly impacted by a rotating blade, resulting in occurrence of hydraulic shock waves within the liquid region adjacent to the impact. The proof-of-concept rotational generator of hydraulic shock treating 9 L of water spiked with viruses was able to achieve 3 logs reduction of viral plaque count within 80–100 liquid passes at moderate blade impact velocities (namely, 70 and 88 m/s) despite the water temperature not exceeding 40 °C and no detectible cavitation. Within the first 20 liquid passes, most MS-2 capsid proteins were degraded, with their concentration reduced from 22 μg/mL to only 7.3 μg/mL. Due to the lack of further capsid protein destruction, additional reduction in MS-2 plaque count in subsequent 80 passes is indicative of damage inflicted to the viral recognition receptors. All this suggests that shockwaves of moderate amplitude (few tens of MPa) alone are sufficient for effective viral inactivation. Considering this and the device's good scalability potential, rotational hydraulic shock generators could prove effective in treating virus-contaminated waters.

Evaluation of an Enzyme-Linked Magnetic Electrochemical Assay for Hepatitis a Virus Detection in Drinking and Vegetable Processing Water

Globally, waterborne viral infections significantly threaten public health. While current European Union regulations stipulate that drinking water must be devoid of harmful pathogens, they do not specifically address the presence of enteric viruses in water used for irrigation or food production. Traditional virus detection methods rely on molecular biology assays, requiring specialized personnel and laboratory facilities. Here, we describe an electrochemical sandwich enzyme-linked immunomagnetic assay (ELIME) for the detection of the hepatitis A virus (HAV) in water matrices. This method employed screen-printed electrodes as the sensing platform and utilized commercially available pre-activated magnetic beads to provide a robust foundation for the immunological reaction. The ELIME assay demonstrated exceptional analytical performance in only 185 min achieving a detection limit of 0.5 genomic copies per milliliter (g.c./mL) and exhibiting good reproducibility with a relative standard deviation (RSD) of 7% in HAV-spiked drinking and processing water samples. Compared with the real-time RT-qPCR method described in ISO 15216-1, the ELIME assay demonstrated higher sensitivity, although the overall linearity of the method was moderate. These analytical attributes highlight the potential of the ELIME assay as a rapid and viable alternative for HAV detection in water used for agriculture and food processing.

Assessing the prevalence of FRNA bacteriophages and their correlation with SARS-CoV-2 RNA in the wastewater of Mumbai city

ABSTRACT Bacteriophages have been explored as indicators of the presence of human viruses in water. F+ coliphages are of particular interest due to their abundance in wastewater and some groups surviving the treatment process. This study assessed the prevalence of F+ coliphages and FRNA bacteriophage (FRNAPH) groups in the wastewaters of Mumbai city and explored its correlation with the presence of SARS-CoV-2. Wastewater samples (raw = 63, treated = 99) collected from three wastewater treatment plants (WWTPs) were assessed for F+ coliphages, FRNAPH groups and SARS-CoV-2. Of the 63 raw wastewater samples, 92% were positive for F+ coliphages and FRNAPH, while SARS-CoV-2 was detected in 76% of samples; FRNAPH GI RNA was the most prevalent (96.82%) followed by FRNAPH GII (77.77%), FRNAPH GIII (36.50%), and FRNAPH GIV (4.76%). A significant correlation was observed between the occurrence of SARS-CoV-2 and F+ coliphages, FRNAPH GII and FRNAPH GIII RNA copies and also between F+ coliphages and FRNAPH GII and GIII. These observations suggest that F+ coliphages, FRNAPH GII and GIII can be explored further as indicators of SARS-CoV-2 in wastewaters. Also, F+ coliphage detection may be a cost-effective and practical approach for monitoring virus elimination during wastewater treatment.

High-density Co-Nx sites anchored on biomass-based carbon nanotubes for efficient removal of plant viruses in water

In this study, we selected rice straw, wheat straw and corn cob as raw materials to successfully prepare cobalt-nitrogen co-doped biomass-based carbon nanotubes composites (BM@CoNCNTs) with Co-Nx sites highly dispersed on porous biochar carrier, which could effectively activate peroxymonosulfate (PMS) to remove tobacco mosaic virus (TMV) in water. Particularly, BM@CoNCNTs-CC, with its confined carbon nanotubes and high-density Co-Nx sites, enhanced the Co2+/Co3+ cycle and direct adsorption of PMS to generate Co(IV)=O and 1O2, playing a dominant role. This led to the effective disruption of TMV coat protein and degradation of its genome within 5 min, achieving up to 6 log10 removal efficiency. Additionally, BM@CoNCNTs-CC/PMS system maintained efficient catalytic removal performance even in complex water matrices (river water and tap water). Overall, our research not only elucidates the production of efficient biomass-based catalysts for environmental remediation, but also highlights the application potential of biomass-based carbon nanotubes composites enriched with Co-Nx sites.

Assessing viral freshwater hazard using a toxicokinetic model and Dreissena polymorpha

The detection all pathogenic enteric viruses in water is expensive, time-consuming, and limited by numerous technical difficulties. Consequently, using reliable indicators such as F-specific RNA phages (FRNAPH) can be well adapted to assess the risk of viral contamination of fecal origin in surface waters. However, the variability of results inherent to the water matrix makes it difficult to use them routinely and to interpret viral risk. Spatial and temporal variability of surface waters can lead to underestimate this risk, in particular in the case of low loading. The use of bivalve mollusks as accumulating systems appears as a promising alternative, as recently highlighted with the freshwater mussel Dreissena polymorpha, but its capacity to accumulate and depurate FRNAPH needs to be better understood and described. The purpose of this study is to characterise the kinetics of accumulation and elimination of infectious FRNAPH by D. polymorpha in laboratory conditions, formalised by a toxico-kinetic (TK) mechanistic model. Accumulation and depuration experiments were performed at a laboratory scale to determine the relationship between the concentration of infectious FRNAPH in water and the concentration accumulated by D. polymorpha. The mussels accumulated infectious FRNAPH (3–5.4 × 104 PFU/g) in a fast and concentration-dependent way in only 48 h, as already recently demonstrated. The second exposure demonstrated that the kinetics of infectious FRNAPH depuration by D. polymorpha was independent to the exposure dose, with a T90 (time required to depurate 90 % of the accumulated concentration) of approximately 6 days. These results highlight the capacities of D. polymorpha to detect and reflect the viral pollution in an integrative way and over time, which is not possible with point water sampling. Different TK models were fitted based on the concentrations measured in the digestive tissues (DT) of D. polymorpha. The model has been developed to formalise the kinetics of phage accumulation in mussels tissues through the simultaneous estimation of accumulation and depuration rates. This model showed that accumulation depended on the exposure concentration, while depuration did not. Standardized D. polymorpha could be easily transplanted to the environment to predict viral concentrations using the TK model defined in the present study to predict the level of contamination of bodies of water on the basis of the level of phages accumulated by the organisms. It will be also provide a better understanding of the dynamics of the virus in continental waters at different time and spatial scales, and thereby contribute to the protection of freshwater resources.

Ozone, hydrogen peroxide, and peroxymonosulfate disinfection of MS2 coliphage in water.

The control of viruses in water is critical to preventing the spread of infectious viral diseases. Many oxidants can inactivate viruses, and this study aims to systematically compare the disinfection effects of ozone (O3), peroxymonosulfate (PMS), and hydrogen peroxide (H2O2) on MS2 coliphage. The effects of oxidant dose and contact time on disinfection were explored, as were the disinfection effects of three oxidizing agents in secondary effluent. The 4-log inactivation of MS2 coliphage required 0.05 mM O3, 0.5 mM PMS, or 25 mM H2O2 with a contact time of 30 min. All three oxidants achieved at least 4-log disinfection within 30 min, and O3 required only 0.5 min. In secondary effluent, all three oxidants also achieved 4-log inactivation of MS2 coliphage. Excitation-emission matrix (EEM) results indicate that all three oxidants removed dissolved organic matter synchronously and O3 oxidized dissolved organic matter more thoroughly while maintaining disinfection efficacy. Considering the criteria of oxidant dose, contact time, and disinfection efficacy in secondary effluent, O3 is the best choice for MS2 coliphage disinfection among the three oxidants.

Sunlight Inactivation of Enveloped Viruses in Clear Water.

Enveloped virus fate in the environment is not well understood; there are no quantitative data on sunlight inactivation of enveloped viruses in water. Herein, we measured the sunlight inactivation of two enveloped viruses (Phi6 and murine hepatitis virus, MHV) and a nonenveloped virus (MS2) over time in clear water with simulated sunlight exposure. We attenuated UV sunlight wavelengths using long-pass 50% cutoff filters at 280, 305, and 320 nm. With the lowest UV attenuation tested, all decay rate constants (corrected for UV light screening, k̂) were significantly different from dark controls; the MS2 k̂ was equal to 4.5 m2/MJ, compared to 16 m2/MJ for Phi6 and 52 m2/MJ for MHV. With the highest UV attenuation tested, only k̂ for MHV (6.1 m2/MJ) was different from the dark control. Results indicate that the two enveloped viruses decay faster than the nonenveloped virus studied, and k̂ are significantly impacted by UV attenuation. Differences in k̂ may be due to the presence of viral envelopes but may also be related to other differing intrinsic properties of the viruses, including genome length and composition. Reported k̂ values can inform strategies to reduce the risk from exposure to enveloped viruses in the environment.

Flow Virometry: A Fluorescence-Based Approach to Enumerate Bacteriophages in Liquid Samples.

Correctly designed flow cytometry (virometry) assays allow accurate detection and enumeration of viruses in water. However, rigorous controls and calibrators are needed to obtain quality data. In the absence of proper controls, the use of fluorescent dyes for virus enumeration can produce false positive signals and lead to the wrong estimation of total virus counts by misreporting colloid particles as virions. Here we describe a protocol that addresses the problems that might potentially confound virometry data accuracy.

Cold plasma within a stable supercavitation bubble – A breakthrough technology for efficient inactivation of viruses in water

Water scarcity, one of the most pressing challenges we face today, has developed for many reasons, including the increasing number of waterborne pollutants that affect the safety of the water environment. Waterborne human, animal and plant viruses represent huge health, environmental, and financial burden and thus it is important to efficiently inactivate them. Therefore, the main objective of this study was to construct a unique device combining plasma with supercavitation and to evaluate its efficiency for water decontamination with the emphasis on inactivation of viruses. High inactivation (>5 log10 PFU/mL) of bacteriophage MS2, a human enteric virus surrogate, was achieved after treatment of 0.43 L of recirculating water for up to 4 min. The key factors in the inactivation were short-lived reactive plasma species that damaged viral RNA. Water treated with plasma for a short time required for successful virus inactivation did not cause cytotoxic effects in the in vitro HepG2 cell model system or adverse effects on potato plant physiology. Therefore, the combined plasma-supercavitation device represents an environmentally-friendly technology that could provide contamination-free and safe water.

Development of innovative health guardian: UV-C disinfection with solar battery charging

In today's world, the advancement of standard technology is accompanied by various challenges. The year 2019 experienced significant challenges that led to changes in several areas, particularly health. Most horrifyingly, many knowledgeable researchers and medical professionals have tried to find the solution but failed. This virus has not yet been cured. Many nations have proclaimed a state of emergency and issued movement control directives due to the virus's millions of fatalities and deep psychological scars. As a result, the government has taken several steps to stop the spread. However, The COVID-19 issue is still a challenge even after the availability of medicine and vaccine. Consequently, this effort is a step towards assisting us in avoiding this deadly infection. The initiative uses light technology, which efficiently kills viruses in water, air and germs. There are three types of UV rays: UV-A, UV-B, and UV-C. The nanometer-scale wavelength of these lights distinguishes them from one another. The wavelengths between 100 and 280nm are the most efficient for this eradication procedure. Additionally, this project makes use of solar-generated renewable energy. In conclusion, we always have strategies to avoid these COVID-19 symptoms because of the currents of modernity.

Assessment of microbial species inactivation and purification of sewage by a gas–liquid diaphragm discharge plasma

The presence of bacteria and viruses in water has caused many large-scale water disease outbreaks. Cold atmospheric plasma has received much attention as an emerging non-thermal purification technology capable of eliminating micro-organisms, non-ferrous fuels, and heavy metals from water. In this study, a novel gas–liquid diaphragm discharge device that generates air plasma driven by a sinusoidal AC power supply was designed, and its sterilizing effect was investigated. First, the concentrations of reactive oxygen and nitrogen species in the diaphragm discharge were characterized, and the physicochemical properties of activated water were explored. Next, experiments on the inactivation of Pseudomonas aeruginosa were carried out using the device. Finally, pond sewage was treated with the device, and the diversity of micro-organisms in the water was analyzed using 16S rRNA assays to further investigate its applicability. The results showed that the species and quantities of micro-organisms in the water significantly reduced after discharge treatment, with the most significant changes occurring in the Bacillus and Firmicutes species. Thus, this study provides an alternative method for microbial inactivation in sewage treatment.

Smart Water Tank Level Detection

As the world around, us transforms and becomes more linked and digitalized, public water management is expected to provide in way. How far are we from achieving a true Smart Water Tank Level Detection, from cutting-edge technology to comfort, safety, reliability, and maintain. We notice that cleanliness of the surrounding area in Water Tank is also important because many people using by water stoaring tank, so how much west water is collected in the any other tank. As a result, we are implementing this approach and developing a green and complete water management city. Because of the day by day by many variant viruses in water and clean water is minimum available of sources, the smart water tank finder is primarily focused on human health, The human body will be affected, and the human life span will be reduced. So, by employing this system, the amount of human power necessary will be minimized, and you will be notified automatically on your mobile screen when a water tank needs to be disconnected supply or when an order is detected. Another sensor, ultrasonic sensor

Inactivation of the enveloped virus phi6 with hydrodynamic cavitation

The COVID −19 pandemic reminded us that we need better contingency plans to prevent the spread of infectious agents and the occurrence of epidemics or pandemics. Although the transmissibility of SARS-CoV-2 in water has not been confirmed, there are studies that have reported on the presence of infectious coronaviruses in water and wastewater samples. Since standard water treatments are not designed to eliminate viruses, it is of utmost importance to explore advanced treatment processes that can improve water treatment and help inactivate viruses when needed. This is the first study to investigate the effects of hydrodynamic cavitation on the inactivation of bacteriophage phi6, an enveloped virus used as a SARS-CoV-2 surrogate in many studies. In two series of experiments with increasing and constant sample temperature, virus reduction of up to 6.3 logs was achieved. Inactivation of phi6 at temperatures of 10 and 20 °C occurs predominantly by the mechanical effect of cavitation and results in a reduction of up to 4.5 logs. At 30 °C, the reduction increases to up to 6 logs, where the temperature-induced increased susceptibility of the viral lipid envelope makes the virus more prone to inactivation. Furthermore, the control experiments without cavitation showed that the increased temperature alone is not sufficient to cause inactivation, but that additional mechanical stress is still required. The RNA degradation results confirmed that virus inactivation was due to the disrupted lipid bilayer and not to RNA damage. Hydrodynamic cavitation, therefore, has the potential to inactivate current and potentially emerging enveloped pathogenic viruses in water at lower, environmentally relevant temperatures.

In Vitro Viral Recovery Yields under Different Re-Suspension Buffers in Iron Flocculation to Concentrate Viral Hemorrhagic Septicemia Virus Genotype IVa in Seawater.

Iron flocculation is widely used to concentrate viruses in water, followed by Fe-virus flocculate formation, collection, and elution. In the elution stage, an oxalic or ascorbic acid re-suspension buffer dissolved iron hydroxide. After the concentration of viral hemorrhagic septicemia virus (VHSV) in seawater (1 × 101 to 1 × 105 viral genome copies or plaque-forming unit (PFU)/mL), the recovery yield of the viral genome using quantitative real-time PCR (qRT-PCR) and viral infectivity using the plaque assay were investigated to evaluate the validity of the two re-suspension buffers to concentrate VHSV. The mean viral genome recovery yield with oxalic and ascorbic acid was 71.2 ± 12.3% and 81.4 ± 9.5%, respectively. The mean viral infective recovery yields based on the PFU were significantly different between the two buffers at 23.8 ± 22.7% (oxalic acid) and 4.4 ± 2.7% (ascorbic acid). Notably, although oxalic acid maintains viral infectivity over 60% at a viral concentration above 105 PFU/mL, the infective VHSVs were not sufficiently recovered at a low viral concentration (102 PFU/mL, <10%). To support this result, concentrated VHSV was inoculated in Epithelioma papulosum cyprini (EPC) cells to confirm cell viability, viral gene expression, and extracellular viral titer. All results demonstrated that oxalic acid buffer was superior to ascorbic acid buffer in preserving viral infectivity.

Potential risk of plant viruses entering disease cycle in surface water in protected vegetable growing areas of Eastern China.

With the expansion of protected vegetable growing areas (PVGAs), viral plant diseases have become more prevalent, causing severe economic losses to the vegetable production industry in China. At present, researches on plant viruses mainly focus on plants, but there is only a few reports on the species of viruses in surface water from PVGAs. The surface water samples in PVGAs are representative to a certain extent, which has an important reference value for studying the characteristics of plant viruses in surface water. The purpose of this study was to identify the diversity and the possibility of entering disease infection cycle of plant viruses in water samples collected from PVGAs in eastern China. A total of 144 water samples were collected, and eight plant viruses including tobacco mosaic virus (TMV, 8.33%), cucumber green mottle mosaic virus (CGMMV, 33.33%), pepper mild mottle virus (PMMoV, 6.94%), cucumber mosaic virus (CMV, 0.69%), tomato masaic virus (ToMV, 3.47%), tomato mottle mosaic virus (ToMMV, 0.69%), tomato chlorosis virus (ToCV, 4.17%), and tomato yellow leaf curl virus (TYLCV, 5.56%) were examined using RT-PCR and PCR. The species of viruses in surface water varied greatly by location. CGMMV, TMV, ToCV, ToMV, ToMMV, and TYLCV were identified in Shandong, a northern part of Eastern China, whereas only PMMoV was found in Shanghai, a southern part of Eastern China. After healthy tobacco plants were inoculated with the concentrated solutions of TMV, ToMV, CGMMV, and PMMoV, could cause disease in healthy tobacco, indicating that the plant viruses in the concentrated solution have the infectivity, and the plant viruses in surface water have the possibility of entering the infection cycle of disease. The results will improve the understanding of the potential risks of waterborne disease transmission.

Human Oncogenic Epstein–Barr Virus in Water and Human Blood Infection of Communities in Phayao Province, Thailand

Water can contain pathogenic viruses. Many studies on RNA virus sources have shown that water can transmit them. However, there are few reports on pathogenic DNA virus transmission through water, such as adenovirus, which pose a widespread public health risk. Therefore, this study aimed to show waterborne viral transmission by detecting viruses in pooled human whole blood samples, tap water, and natural water from Mueang District, Phayao Province, Thailand, using a metagenomic approach. Viral prevalence in whole blood samples was measured by polymerase chain reaction (PCR) and quantitative PCR (qPCR), and environmental factors that affect viral infection were assessed. Metagenomics results showed that Epstein–Barr virus (EBV) members were among the prominent cancer-associated oncogenic DNA viruses detected in human blood and all water types similar to the EBV reference sequence (NC_007605). There were 59 out of 813 (7.26%) human whole blood samples that were positive for EBV DNA based on PCR and qPCR for the EBNA-1 and EBNA-2 genes. Water- and blood-borne human oncogenic EBV should be a concern in tap water treatment and blood transfusion in patients, respectively. Therefore, the detection of EBV in water suggests that transmission via water is possible and should be investigated further.

Combination of Fe(OH)3 modified diatomaceous earth and qPCR for the enrichment and detection of African swine fever virus in water.

Water is one of the primary vectors for African swine fever virus (ASFV) transmission among swine herds. However, the low concentrations of ASFV in water represent a challenge for the detection of the virus by conventional PCR methods, and enrichment of the virus would increase the test sensitivity. In this study, aiming to enrich ASFV in water quickly and efficiently, a rapid and efficient water-borne virus enrichment system (MDEF, modified diatomaceous earth by ferric hydroxide colloid) was used to enrich ASFV in water. After enrichment by MDEF, conventional real-time PCR (qPCR) was used for ASFV detection. ASFV were inactivated and diluted in 10 L of water, of which 4 mL were collected after 60 min treatment using the MDEF system. Two thousand five hundred times reduction of the sample volume was achieved after enrichment. A high adsorption rate of about 99.99 (±0.01)% and a high recovery rate of 64.01 (±10.20)% to 179.65 (±25.53)% was achieved by using 1g modified diatomaceous earth for 10 L ASFV contaminated water. The limit of qPCR detection of ASFV decreased to 1 × 10-1.11 GU ml-1 (genomic units per milliliter) from 1 × 102.71 GU ml-1 after concentrating the spiked water from 10 L to 4 ml. Preliminary application of MDEF allowed successful detection of African swine fever virus (ASFV), porcine circovirus type 2 (PCV2), and pseudorabies virus (PRV) in sewage. Thus, the combination of modified diatomaceous earth and real-time PCR is a promising strategy for the detection of viruses in water.

GCRV NS38 counteracts SVCV proliferation by intracellular antagonization during co-infection

Viral co-infection has been found in animals; however, the mechanisms of co-infection are unclear. The abundance and diversity of viruses in water make fish highly susceptible to co-infection. Here, we reported a co-infection in fish, which resulted in reduced host lethality and illustrated the intracellular molecular mechanism of viral co-infection. The spring viremia of carp virus (SVCV) is a highly lethal virus that infects Cyprinidae, such as zebrafish. The mortality of SVCV infection was significantly reduced when co-infected with the grass carp reovirus (GCRV). The severity of tissue damage and viral proliferation of SVCV was also reduced in co-infection with GCRV. The transcriptome bioinformatics analysis demonstrated that the effect on the host transcripts in response to SVCV infection was significantly reduced in co-infection. After excluding the extracellular interactions of these two viruses, the intracellular mechanisms were studied. We found that the GCRV NS38 remarkably decreased SVCV infection and viral proliferation. The interaction between GCRV NS38 and SVCV nucleoprotein (N) and phosphoprotein (P) proteins was identified, and NS38 downregulated both N and P proteins. Further analysis demonstrated that the N protein was degraded by NS38 indispensable of the autophagy receptor, sequestosome 1 (p62). Meanwhile, K63-linked ubiquitination of the P protein was reduced by NS38, leading to ubiquitinated degradation of the P protein. These results reveal that the intracellular viral protein interactions are a crucial mechanism of co-infection and influence the host pathology and expand our understanding in intracellular viral interactions co-infection.

Evaluation of disinfection efficacy of single UV-C, and UV-A followed by UV-C LED irradiation on Escherichia coli, B. spizizenii and MS2 bacteriophage, in water

Ultraviolet light-emitting diodes (UV LEDs) have shown ability to inactivate microorganisms and viruses in water. The unique characteristic of the UV-LEDs' diversity in wavelengths ranging from UV-C, UV-B, and UV-A, allows for wavelengths to be combined in different manners for polychromatic irradiation. Previous studies reported no synergy from simultaneous or sequential UV-C and UV-B as well as UV-C or UV-B followed by UV-A irradiation. However, synergy was reported for UV-A followed by UV-C or UV-B irradiation on various microorganisms. Nevertheless, no clear ground has been reached on whether to adopt single UV-C wavelengths or UV-A followed by UV-C LED, irradiation on inactivation of microorganisms and viruses in water. Therefore, this work evaluates the disinfection efficacy of single UV-C as well as UV-A followed by UV-C LED irradiation on Escherichia coli, Bacillus spizizenii spores and MS2 bacteriophage in water. The UV-C wavelengths were represented by 267 and 278 nm UV LEDs, and UV-A by 368 nm UV LEDs. In this study, E. coli was highly susceptible to UV radiation followed by B. spizizenii spores, and lastly MS2. Repair following UV inactivation was only observed in E. coli. The synergistic effect found in both E. coli, and B. spizizenii spores was attributed to the different inactivation mechanisms of the UV-C and UV-A wavelengths. In both single UV-C, and UV-A followed by UV-C LED irradiations, single 267 nm UV-C LED showed higher inactivation efficacy. Meanwhile, single 278 nm UV-C LED showed higher efficacy in terms of suppression of repair, and electrical energy consumption. Using single UV-C LEDs in a water disinfection system cuts down on related extra costs by avoiding combined wavelengths while still attaining better levels of microorganism inactivation, repair suppression and electrical energy consumption. These findings are applicable for the design and implementation of UV LED water disinfection systems.

Dye-based dual-emission Eu-MOF synthesized by Post-modification for the sensitive ratio fluorescence visualization sensing of ClO-

As we all know, excessive hypochlorite will be transformed into highly toxic substances, while insufficient hypochlorite can not completely kill bacteria and viruses in water. Therefore, it is desirable to develop a new analytical method to detect ClO- in environmental water. Here, a novel and simple fluorescence sensor was constructed for monitoring ClO- by an effective strategy. An Acriflavine@lanthanide metal-organic framework (Acr@Eu(BTEC)) was designed by covalently integrating amino-rich dye (Acr) and carboxyl-rich Eu(BTEC) via post-synthesis method. The created fluorescence sensor has two emission centers originating from Acr and Eu(BTEC), respectively. In the presence of ClO-, the strong green fluorescence derived from Acr was significantly quenched, while the invariant red emission from Eu3+ acted as the reference signal. Thus, Acr@Eu(BTEC) with two emissions was developed as a ratiometric fluorescence sensor for highly sensitive and selective detection of ClO-. The limit of detection (LOD) was as low as 10.75 nM. Moreover, visual detection of ClO- by the naked eyes is feasible with obvious fluorescent color changes from green to orange and then red. This method shows excellent performance in practical application, which suggests that it has great potential in water quality monitoring.