Browsing by Author "Mao, Kang"
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Item Open Access Bioaccumulation of Hg in rice leaf facilitates selenium bioaccumulation in rice (Oryza sativa L.) leaf in the Wanshan mercury mine(ACS, 2020-02-26) Chang, Chuanyu; Chen, Chongying; Yin, Runsheng; Shen, Yuan; Mao, Kang; Yang, Zhugen; Feng, Xinbin; Zhang, HuaMercury (Hg) bioaccumulation in rice poses a health issue for rice consumers. In rice paddies, selenium (Se) can decrease the bioavailability of Hg through forming the less bioavailable Hg selenides (HgSe) in soil. Rice leaves can directly uptake a substantial amount of elemental Hg from the atmosphere, however, whether the bioaccumulation of Hg in rice leaves can affect the bioaccumulation of Se in rice plants is not known. Here, we conducted field and controlled studies to investigate the bioaccumulation of Hg and Se in the rice-soil system. In the field study, we observed a significantly positive correlation between Hg concentrations and BAFs of Se in rice leaves (r2 = 0.60, p < 0.01) collected from the Wanshan Mercury Mine, SW China, suggesting that the bioaccumulation of atmospheric Hg in rice leaves can facilitate the uptake of soil Se, perhaps through the formation of Hg-Se complex in rice leaves. This conclusion was supported by the controlled study, which observed significantly higher concentrations and BAFs of Se in rice leaf at a high atmospheric Hg site at WMM, compared to a low atmospheric Hg site in Guiyang, SW China.Item Open Access Biosensors for wastewater-based epidemiology for monitoring public health(Elsevier, 2020-12-25) Mao, Kang; Zhang, Hua; Pan, Yuwei; Yang, ZhugenPublic health is attracting increasing attention due to the current global pandemic, and wastewater-based epidemiology (WBE) has emerged as a powerful tool for monitoring of public health by analysis of a variety of biomarkers (e.g., chemicals and pathogens) in wastewater. Rapid development of WBE requires rapid and on-site analytical tools for monitoring of sewage biomarkers to provide immediate decision and intervention. Biosensors have been demonstrated to be highly sensitive and selective tools for the analysis of sewage biomarkers due to their fast response, ease-to-use, low cost and the potential for field-testing. This paper presents biosensors as effective tools for wastewater analysis of potential biomarkers and monitoring of public health via WBE. In particular, we discuss the use of sewage sensors for rapid detection of a range of targets, including rapid monitoring of community-wide illicit drug consumption and pathogens for early warning of infectious diseases outbreaks. Finally, we provide a perspective on the future use of the biosensor technology for WBE to enable rapid on-site monitoring of sewage, which will provide nearly real-time data for public health assessment and effective intervention.Item Open Access Can a paper-based device trace COVID-19 sources with wastewater-based epidemiology?(ACS, 2020-03-23) Mao, Kang; Zhang, Hua; Yang, ZhugenA recent outbreak of novel coronavirus pneumonia (COVID-19) caused by SARS-CoV-2 infection has spread rapidly around the globe, with cases now confirmed in 130 countries worldwide. Although public health authorities are racing to contain the spread of COVID-19 around the world, the situation is still grim. About 158 111 confirmed cases and 5946 cumulative deaths (81 059 confirmed cases and 3204 cumulative deaths from China) have been reported around the globe as of March 15, 2020. Some clinical cases have found that some carriers of the virus may be asymptomatic, with no fever, and no, or only slight symptoms of infection. Without the ability to screen these asymptomatic patients quickly and effectively, these unsuspecting carriers have the potential to increase the risk of disease transmission if no early effective quarantine measures are implemented. Therefore, to trace unknown COVID-19 sources, fast and accurate screening of potential virus carriers and diagnosis of asymptomatic patients is a crucial step for intervention and prevention at the early stage.Item Open Access Comprehensive review of the basic chemical behaviours, sources, processes, and endpoints of trace element contamination in paddy soil-rice systems in rice-growing countries(Elsevier, 2020-04-21) Ali, Waqar; Mao, Kang; Zhang, Hua; Junaid, Muhammad; Xu, Nan; Rasool, Atta; Feng, Xinbin; Yang, ZhugenRice is the leading staple food for more than half of the world’s population, and approximately 160 million hectares of agricultural area worldwide are under rice cultivation. Therefore, it is essential to fulfil the global demand for rice while maintaining food safety. Rice acts as a sink for potentially toxic metals such as arsenic (As), selenium (Se), cadmium (Cd), lead (Pb), zinc (Zn), manganese (Mn), nickel (Ni), and chromium (Cr) in paddy soil-rice systems due to the natural and anthropogenic sources of these metals that have developed in the last few decades. This review summarizes the sources and basic chemical behaviours of these trace elements in the soil system and their contamination status, uptake, translocation, and accumulation mechanisms in paddy soil-rice systems in major rice-growing countries. Several human health threats are significantly associated with these toxic and potentially toxic metals not only due to their presence in the environment (i.e., the soil, water, and air) but also due to the uptake and translocation of these metals via different transporters. Elevated concentrations of these metals are toxic to plants, animals, and even humans that consume them regularly, and the uniform deposition of metals causes a severe risk of bioaccumulation. Furthermore, the contamination of rice in the global rice trade makes this a critical problem of worldwide concern. Therefore, the global consumption of contaminated rice causes severe human health effects that require rapid action. Finally, this review also summarizes the available management/remediation measures and future research directions for addressing this critical issue.Item Open Access Efficient removal of Cd(II) from aqueous solution by pinecone biochar: Sorption performance and governing mechanisms(Elsevier, 2020-06-12) Teng, Dongye; Zhang, Bingbing; Xu, Guomin; Wang, Bing; Mao, Kang; Wang, Jianxu; Sun, Jing; Feng, Xinbin; Yang, Zhugen; Zhang, HuaCadmium (Cd) is one of the most harmful and widespread environmental pollutants. Despite decades-long research efforts, the remediation of water contaminated by Cd has remained a significant challenge. A novel carbon material, pinecone biochar, was previously hypothesized to be a promising adsorbent for Cd, while so far, it has received little attention. This study evaluated the sorption capacity of pinecone biochar through isotherm experiments. Based on Langmuir model, the adsorption maximum for Cd(II) was up to 92.7 mg g−1. The mechanism of Cd(II) adsorption on pinecone biochar was also explored through both thermodynamic and kinetics adsorption experiments, as well as both solution and solid-phase microstructure characterization. The solid-solution partitioning behaviour of Cd(II) fitted best with the Tόth model while the adsorption process followed a pseudo-second-order rate, suggesting that the Cd(II) adsorption on the pinecone biochar was mainly a chemisorption process. Microstructure characteristics and mechanism analysis further suggested that coprecipitation and surface complexation were the main mechanisms of Cd adsorption by biochar. Coprecipitation occurred mainly through the forms of Cd(OH)2 and CdCO3. Our results demonstrated that pinecone biochar was an efficient adsorbent which holds a huge potential for Cd(II) removal from aqueous solution.Item Open Access Insights into the mechanisms of arsenic-selenium interactions and the associated toxicity in plants, animals, and humans: a critical review(Taylor and Francis, 2020-03-18) Ali, Waqar; Zhang, Hua; Junaid, Muhammad; Mao, Kang; Xu, Nan; Chang, Chuanyu; Rasool, Atta; Wajahat Aslam, Muhammad; Ali, Jamshed; Yang, ZhugenThis review highlights arsenic (As) and selenium (Se) sources in the environment, their uptake in the soil-plant system, interactions between these metals and the associated toxicity in major biological compartments, which may assist in addressing the hazardous impacts associated with As and Se contamination. The interaction between As and Se is a critical factor for a detailed systematic understanding of the transportation, environmental fate, and associated toxicological effects of these metalloids in plants, animals, and humans. Arsenic and Se induce cytotoxicity and genotoxicity through the generation of reactive oxygen species (ROS). Compared to arsenite (AsIII), methylated arsenicals, including methylarsonous acid (MAsIII) and dimethylarsinous acids (DMAsIII), exhibit more cytotoxic and genotoxic potential to inhibit more potent enzymes and activate the protein AP˗1, which is a critical marker of genetic stability. Methylated AsIII and its associated metabolites are well-known potential carcinogens that induce toxicity by blocking Se metabolism pathway. The imbalance of Se compounds can lead to the generation of ROS, which can inhibit or decrease genomic stability. The As and Se nexus also affect cellular signaling through activation of transcription factors such as NFκB and AP-1.Item Open Access Nanomaterial-based aptamer sensors for analysis of illicit drugs and evaluation of drugs consumption for wastewater-based epidemiology(Elsevier, 2020-07-06) Mao, Kang; Zhang, Hua; Pan, Yuwei; Zhang, Kuankuan; Cao, Haorui; Li, Xiqing; Yang, ZhugenThe abuse of illicit drugs usually associated with dramatic crimes may cause significant problems for the whole society. Wastewater-based epidemiology (WBE) has been demonstrated to be a novel and cost-effective way to evaluate the abuse of illicit drugs at the community level, and has been used as a routine method for monitoring and played a significant role for combating the crimes in some countries, e.g. China. The method can also provide temporal and spatial variation of drugs of abuse. The detection methods mainly remain on the conventional liquid chromatography coupled with mass spectrometry, which is extremely sensitive and selective, however needs advanced facility and well-trained personals, thus limit it in the lab. As an alternative, sensors have emerged to be a powerful analytical tool for a wide spectrum of analytes, in particular aptamer sensors (aptasensors) have attracted increasing attention and could act as an efficient tool in this field due to the excellent characteristics of selectivity, sensitivity, low cost, miniaturization, easy-to-use, and automation. In this review, we will briefly introduce the context, specific assessment process and applications of WBE and the recent progress of illicit drug aptasensors, in particular focusing on optical and electrochemical sensors. We then highlight several recent aptasensors for illicit drugs in new technology integration and discuss the feasibility of these aptasensor for WBE. We will summarize the challenges and propose our insights and opportunity on aptasensor for WBE to evaluate community-wide drug use trends and public health.Item Open Access Nanomaterial-based aptamer sensors for analysis of illicit drugs and evaluation of drugs consumption for wastewater-based epidemiology(Elsevier, 2020-06-06) Mao, Kang; Zhang, Hua; Pan, Yuwei; Zhang, Kuankuan; Cao, Haorui; Li, Xiqing; Yang, ZhugenThe abuse of illicit drugs usually associated with dramatic crimes may cause significant problems for the whole society. Wastewater-based epidemiology (WBE) has been demonstrated to be a novel and cost-effective way to evaluate the abuse of illicit drugs at the community level, and has been used as a routine method for monitoring and played a significant role for combating the crimes in some countries, e.g. China. The method can also provide temporal and spatial variation of drugs of abuse. The detection methods mainly remain on the conventional liquid chromatography coupled with mass spectrometry, which is extremely sensitive and selective, however needs advanced facility and well-trained personals, thus limit it in the lab. As an alternative, sensors have emerged to be a powerful analytical tool for a wide spectrum of analytes, in particular aptamer sensors (aptasensors) have attracted increasing attention and could act as an efficient tool in this field due to the excellent characteristics of selectivity, sensitivity, low cost, miniaturization, easy-to-use, and automation. In this review, we will briefly introduce the context, specific assessment process and applications of WBE and the recent progress of illicit drug aptasensors, in particular focusing on optical and electrochemical sensors. We then highlight several recent aptasensors for illicit drugs in new technology integration and discuss the feasibility of these aptasensor for WBE. We will summarize the challenges and propose our insights and opportunity on aptasensor for WBE to evaluate community-wide drug use trends and public healthItem Open Access Nanomaterial-based aptamer sensors for arsenic detection(Elsevier, 2019-10-15) Mao, Kang; Zhang, Hua; Wang, Zhenglu; Cao, Haorui; Zhang, Kuankuan; Li, Xiqing; Yang, ZhugenArsenic (As) is a highly toxic contaminant in the environment and a serious carcinogen for the human being. The toxicity of arsenic significantly threatens environmental and human health. The effective removing technology for arsenic remains challenging, and one of the reasons is due to the lack of powerful detection method in the complex environmental matrix. There is thus an urgent need to develop novel analytical methods for arsenic, preferably with the potential for the field-testing. To combat arsenic pollution and maintain a healthy environment and eco-system, many advanced analytical methods have been developed for arsenic detection in various samples. Among these strategies, biosensors hold great promise for rapid detection of arsenic, in particular, nanomaterials-based aptamer sensors have attracted significant attention due to their simplicity, high sensitivity and rapidness. In this paper, we reviewed the recent development and promising applications of aptamer sensors (aptasensors) based-on nanomaterial for arsenic detection, in particular with emphasis on the works using optical and electrochemical technologies. We also discussed the recent novel technology in aptasensors development for arsenic detection, including nucleic acid amplification for signal enhancement and device integration for the portability of arsenic sensors. We are hoping this review could inspire further researches in developing novel nanotechnologies based aptasensors for possible on-site detection of arsenic.Item Open Access Occurrence of various viruses and recent evidence of SARS-CoV-2 in wastewater systems(Elsevier, 2021-02-19) Ali, Waqar; Zhang, Hua; Wang, Zhenglu; Chang, Chuanyu; Javed, Asif; Ali, Kamran; Du, Wei; Niazi, Nabeel Khan; Mao, Kang; Yang, ZhugenViruses are omnipresent and persistent in wastewater, which poses a risk to human health. In this review, we summarize the different qualitative and quantitative methods for virus analysis in wastewater and systematically discuss the spatial distribution and temporal patterns of various viruses (i.e., enteric viruses, Caliciviridae (Noroviruses (NoVs)), Picornaviridae (Enteroviruses (EVs)), Hepatitis A virus (HAV)), and Adenoviridae (Adenoviruses (AdVs))) in wastewater systems. Then we critically review recent SARS-CoV-2 studies to understand the ongoing COVID-19 pandemic through wastewater surveillance. SARS-CoV-2 genetic material has been detected in wastewater from France, the Netherlands, Australia, Italy, Japan, Spain, Turkey, India, Pakistan, China, and the USA. We then discuss the utility of wastewater-based epidemiology (WBE) to estimate the occurrence, distribution, and genetic diversity of these viruses and generate human health risk assessment. Finally, we not only promote the prevention of viral infectious disease transmission through wastewater but also highlight the potential use of WBE as an early warning system for public health assessment.Item Open Access Paper device combining CRISPR/Cas12a and reverse-transcription loop-mediated isothermal amplification for SARS-CoV-2 detection in wastewater(American Chemical Society, 2022-08-30) Cao, Haorui; Mao, Kang; Ran, Fang; Xu, Pengqi; Zhao, Yirong; Zhang, Xiangyan; Zhou, Hourong; Yang, Zhugen; Zhang, Hua; Jiang, GuibinWastewater-based surveillance of the COVID-19 pandemic holds great promise; however, a point-of-use detection method for SARS-CoV-2 in wastewater is lacking. Here, a portable paper device based on CRISPR/Cas12a and reverse-transcription loop-mediated isothermal amplification (RT-LAMP) with excellent sensitivity and specificity was developed for SARS-CoV-2 detection in wastewater. Three primer sets of RT-LAMP and guide RNAs (gRNAs) that could lead Cas12a to recognize target genes via base pairing were used to perform the high-fidelity RT-LAMP to detect the N, E, and S genes of SARS-CoV-2. Due to the trans-cleavage activity of CRISPR/Cas12a after high-fidelity amplicon recognition, carboxyfluorescein-ssDNA-Black Hole Quencher-1 and carboxyfluorescein-ssDNA-biotin probes were adopted to realize different visualization pathways via a fluorescence or lateral flow analysis, respectively. The reactions were integrated into a paper device for simultaneously detecting the N, E, and S genes with limits of detection (LODs) of 25, 310, and 10 copies/mL, respectively. The device achieved a semiquantitative analysis from 0 to 310 copies/mL due to the different LODs of the three genes. Blind experiments demonstrated that the device was suitable for wastewater analysis with 97.7% sensitivity and 82% semiquantitative accuracy. This is the first semiquantitative endpoint detection of SARS-CoV-2 in wastewater via different LODs, demonstrating a promising point-of-use method for wastewater-based surveillance.Item Open Access Paper-based devices for rapid diagnosis and wastewater surveillance(Elsevier, 2022-09-06) Pan, Yuwei; Mao, Kang; Hui, Qinxin; Wang, Baojun; Cooper, Jonathan; Yang, ZhugenInfectious diseases are a global concern for public health resulting in high rates of infection with subsequent health and socio-economic impacts through resulting morbidity and mortality. The emergence of such diseases has motivated researchers to develop cost-effective, rapid and sensitive analytical methods and devices to better understand the transmission routes of infections within populations. To this end, rapid and low-cost diagnosis and testing devices for infectious diseases are attracting increasing amounts of attention, e.g., through using paper-based analytical devices (PADs). In this paper, the recent development of PADs is critically reviewed both for the diagnosis of inviduals and population health, by using devices for testing wastewater. Finally, the review also focuses on PADs for the analysis of bacteria and viruses in wastewater, together with a discussion on thee future development of PADs for rapid diagnosis and wastewater surveillance.Item Open Access Paper-based microfluidics for rapid diagnostics and drug delivery(Elsevier, 2020-03-10) Mao, Kang; Min, Xiaocui; Zhang, Hua; Cao, Haorui; Guo, Yongkun; Yang, ZhugenPaper is a common material that is promising for constructing microfluidic chips (lab-on-a-paper) for diagnostics and drug delivery for biomedical applications. In the past decade, extensive research on paper-based microfluidics has accumulated a large number of scientific publications in the fields of biomedical diagnosis, food safety, environmental health, drug screening and delivery. This review focuses on the recent progress on paper-based microfluidic technology with an emphasis on the design, optimization and application of the technology platform, in particular for medical diagnostics and drug delivery. Novel advances have concentrated on engineering paper devices for point-of-care (POC) diagnostics, which could be integrated with nucleic acid-based tests and isothermal amplification experiments, enabling rapid sample-to-answer assays for field testing. Among the isothermal amplification experiments, loop-mediated isothermal amplification (LAMP), an extremely sensitive nucleic acid test, specifically identifies ultralow concentrations of DNA/RNA from practical samples for diagnosing diseases. We thus mainly focus on the paper device-based LAMP assay for the rapid infectious disease diagnosis, foodborne pathogen analysis, veterinary diagnosis, plant diagnosis, and environmental public health evaluation. We also outlined progress on paper microfluidic devices for drug delivery. The paper concludes with a discussion on the challenges of this technology and our insights into how to advance science and technology towards the development of fully functional paper devices in diagnostics and drug delivery.Item Open Access Paper-based nanosensors to evaluate community-wide illicit drug use for wastewater-based epidemiology(Elsevier, 2020-10-23) Mao, Kang; Yang, Zhugen; Zhang, Hua; Li, Xiqing; Cooper, Jonathan M.Wastewater-based epidemiology (WBE) is a powerful technique for monitoring illicit drugs of abuse in the community. Here, we report on a surface-enhanced Raman scattering/spectroscopy (SERS) sensor for the sensitive and selective detection of methamphetamine based on the assembly of noble metal core-shell nanoparticles on a bespoke glassy nanofibrous electrospun paper matrix. The hierarchical structure of the fibrous paper, modified with the synthesized Au@Ag core-shell nanoparticles (Au@Ag) possessing good SERS efficiency, enables us to evaluate the community-wide prevalence of methamphetamine in wastewater treatment plants around Beijing. We show that when normalized for the daily flow of the wastewater treatment plants, higher mass loads of drugs are found in sewage influent from urban areas, implying greater local methamphetamine usage than that in less populated areas. These user-friendly and disposable paper devices demonstrate the applicability of rapid on-site illicit drug detection, illustrating the application to wastewater-based epidemiology, which has the potential to inform government agencies regarding societal interventions.Item Embargo Portable biosensor combining CRISPR/Cas12a and loop-mediated isothermal amplification for antibiotic resistance gene ermB in wastewater(Elsevier, 2023-10-17) Mao, Kang; Zhang, Hua; Ran, Fang; Cao, Haorui; Feng, Rida; Du, Wei; Li, Xiqing; Yang, ZhugenWastewater is among the main sources of antibiotic resistance genes (ARGs) in the environment, but effective methods to quickly assess ARGs on-site in wastewater are lacking. Here, using the typical ARG ermB as the target, we report a portable biosensor combining CRISPR/Cas12a and loop-mediated isothermal amplification (LAMP) for the detection of ARGs. Six primers of LAMP and the crRNA of CRISPR/Cas12a were first designed to be preamplification with LAMP and lead Cas12a to recognize the ermB via base pairing. Due to the trans-cleavage activity of CRISPR/Cas12a after amplicon recognition, ssDNA probes modified with reporter molecules were used to implement a visual assay with lateral flow test strips and fluorescence. After a simple nucleic acid extraction with magnetic beads, the constructed biosensor possesses excellent sensitivity and selectivity as low as 2.75 × 103 copies/μL using fluorescence and later flow strips in wastewater. We further evaluated the community-wide prevalence of ermB in wastewater influent and found high mass loads of ermB during different months. This user-friendly and low-cost biosensor is applicable for rapid on-site ARG detection, providing a potential point-of-use method for rapid assessments of ARG abundance in wastewater from large city areas with many wastewater treatment plants and in resource-limited rural areas.Item Open Access The potential of an integrated biosensor system with mobile health and wastewater-based epidemiology (iBMW) for the prevention, surveillance, monitoring and intervention of the COVID-19 pandemic(Elsevier, 2020-09-16) Mao, Kang; Zhang, Hua; Yang, ZhugenThe outbreak of novel coronavirus pneumonia (COVID-19) has caused a significant public health challenge worldwide. A lack of effective methods for screening potential patients, rapidly diagnosing suspected cases, and accurately monitoring the epidemic in real time to prevent the rapid spread of COVID-19 raises significant difficulties in mitigating the epidemic in many countries. As effective point-of-care diagnosis tools, simple, low-cost and rapid sensors have the potential to greatly accelerate the screening and diagnosis of suspected patients to improve their treatment and care. In particular, there is evidence that multiple pathogens have been detected in sewage, including SARS-CoV-2, providing significant opportunities for the development of advanced sensors for wastewater-based epidemiology that provide an early warning of the pandemic within the population. Sensors could be used to screen potential carriers, provide real-time monitoring and control of the epidemic, and even support targeted drug screening and delivery within the integration of emerging mobile health (mHealth) technology. In this communication, we discuss the feasibility of an integrated point-of-care biosensor system with mobile health for wastewater-based epidemiology (iBMW) for early warning of COVID-19, screening and diagnosis of potential infectors, and improving health care and public health. The iBMW will provide an effective approach to prevent, evaluate and intervene in a fast, affordable and reliable way, thus enabling real-time guidance for the government in providing effective intervention and evaluating the effectiveness of intervention.Item Open Access Rapid duplexed detection of illicit drugs in wastewater using gold nanoparticle conjugated aptamer sensors(Elsevier, 2019-06-22) Mao, Kang; Ma, Jun; Li, Xiqing; Yang, ZhugenThe abuse of illicit drug addiction is a worldwide public health and social problem. In this paper, we reported on a simple and rapid colorimetric biosensor for duplexed detection of methamphetamine (METH) and cocaine in a single assay. Gold nanoparticles (AuNPs) and Au@Ag NPs were synthesized and functionalized with DNA reporter probes (RPs) for METH and cocaine, respectively. The magnetic beads (MBs) were conjugated with two capture probes (CPs) respective to METH and cocaine. The respective RPs and CPs were designed to hybridize with each illicit drug-binding DNA aptamers through DNA-DNA hybridization, forming a sandwich structure. This MBs-based sandwich structure could be removed with an external magnetic field. However, due to the higher affinity of DNA aptamers with illicit drugs, the sandwich structure was disassembled when illicit drugs are introduced into the solution, leading to the colour changes of the supernatant. Utilizing a non-negative matrix factorization (NMF) algorithm to process the data, we demonstrated the ability of our biosensor for the simultaneous quantification of two illicit drugs. Under the optimal condition, our sensors were able to detect both METH and cocaine at the nM level with a wide dynamic range. This sensing platform provides a huge potential on drug consumption evaluation at the community level for wastewater-based epidemiology.Item Open Access Rolling circle amplification as an efficient analytical tool for rapid detection of contaminants in aqueous environments(MDPI, 2021-09-23) Zhang, Kuankuan; Zhang, Hua; Cao, Haorui; Jiang, Yu; Mao, Kang; Yang, ZhugenEnvironmental contaminants are a global concern, and an effective strategy for remediation is to develop a rapid, on-site, and affordable monitoring method. However, this remains challenging, especially with regard to the detection of various contaminants in complex water environments. The application of molecular methods has recently attracted increasing attention; for example, rolling circle amplification (RCA) is an isothermal enzymatic process in which a short nucleic acid primer is amplified to form a long single-stranded nucleic acid using a circular template and special nucleic acid polymerases. Furthermore, this approach can be further engineered into a device for point-of-need monitoring of environmental pollutants. In this paper, we describe the fundamental principles of RCA and the advantages and disadvantages of RCA assays. Then, we discuss the recently developed RCA-based tools for environmental analysis to determine various targets, including heavy metals, organic small molecules, nucleic acids, peptides, proteins, and even microorganisms in aqueous environments. Finally, we summarize the challenges and outline strategies for the advancement of this technique for application in contaminant monitoring.