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Real-time monitoring of different types of intracellular tumor-related biomarkers is of key importance for the identification of tumor cells. However, it is hampered by the low abundance of biomarkers, inefficient free diffusion of reactants, and complex cytoplasmic milieu. Herein, we present a stable and general method for in situ imaging of microRNA-21 and telomerase utilizing simple highly integrated dual tetrahedral DNA nanostructures (TDNs) that can naturally enter cells, which could initiate to form the three-dimensional (3D) higher-order DNA superstructures (DNA nanofireworks, DNFs) through a reliable target-triggered entropy-driven strand displacement reaction in living cells for remarkable signal amplification. Importantly, the excellent biostability, biocompatibility, and sensitivity of this approach benefited from (i) the precise multidirectional arrangement of probes with a pure DNA structure and (ii) the local target concentration enhanced by the spatially confined microdomain inside the DNFs. This strategy provides a pivotal molecular toolbox for broad applications such as biomedical imaging and early precise cancer diagnosis.

Wastewater surveillance enables tracking infectious disease dynamics and community prevalence quantification for public health. However, the testing requirement of centralized laboratories and well-trained staff challenges underserved areas and low-resource settings. The development of new rapid and low-cost sensors enables in-field testing of wastewater from the community to the individual building levels for early warning of pandemics.

Graphene oxide (GO)-based membranes have been widely studied for realizing efficient wastewater treatment, due to their easily functionalizeable surfaces and tunable interlayer structures. However, the irregular structure of water channels within GO-based membrane has largely confined water permeance and prevented the simultaneously improvement of purification performance. Herein, we purposely construct the well-structured three-dimensional (3D) water channels featuring regular and negatively-charged properties in the GO/SiO2 composite membrane via in situ close-packing assembly of SiO2 nanoparticles onto GO nanosheets. Such regular 3D channels can improve the water permeance to a record-high value of 33,431.5 ± 559.9 L·m−2·h−1 (LMH) bar−1, which is several-fold higher than those of current state-of-the-art GO-based membranes. We further demonstrate that benefiting from negative charges on both GO and SiO2, these negatively-charged 3D channels enable the charge selectivity well toward dye in wastewater where the rejection for positive-charged and negative-charged dye molecules is 99.6% vs. 7.2%, respectively. The 3D channels can also accelerate oil/water (O/W) separation process, in which the O/W permeance and oil rejection can reach 19,589.2 ± 1,189.7 LMH bar−1 and 98.2%, respectively. The present work unveils the positive role of well-structured 3D channels on synchronizing the remarkable improvement of both water permeance and purification performance for highly efficient wastewater treatment.

Wastewater-based epidemiology WBE has shown to be an innovative and promising tool for the estimation of community-wide health such as drugs, alcohol, and tobacco use in the past couple of decades since it was proposed in the beginning of 21 centuries. Since the first report from the Netherland in March 2020 on the presence of viral RNA fragment of SARS-CoV-2 in wastewater, WBE, also namely, wastewater surveillance, has been rapidly emerged as a new public health tool for the monitoring of pathogens to establish the early warning for the pandemic, which can provide the complementary data sets for the clinical testing. For example, viral RNA of SARS-CoV-2 can be monitored in the community at the early stage, effective measures can be taken as early as possible to minimize the pathogen spread.

Rapid, sensitive, and selective detection of live pathogens remains a key priority for quality control and risk assessment. While conventional methods often require complicated workflows, costly reagents, lab equipment, and are time-consuming, rendering them inadequate for field testing and low-resource settings. Increased attention has been drawn to developing alternative low-cost and rapid methods to detect on-site live pathogens in different environmental matrices. Among them, microfluidic devices that integrate various laboratory functions in a miniaturized manner have proven to be a promising tool for the rapid and sensitive detection of pathogens. Herein, the development of microfluidic devices specifically designed for the detection of live pathogens is discussed along a concise summary of novel microfluidics systems recently developed, contrasted to conventional methods regarding assay time, the limit of detection, and target organisms. These include a variety of micro total analysis systems (µTAS) and microfluidic paper-based analytical devices (µPADs) in combination with molecular methods and traditional live cell detection techniques, such as cell culture, DNA intercalating dyes, resazurin, and immobilized bioreceptors (e.g., aptamers and capture antibodies). Furthermore, insights on the future perspectives of microfluidics for live pathogen detection with a highlight on the rapid and low-cost method development for field testing are provided.

Wastewater-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.

The transfer of large-area and clean graphene to arbitrary substrates, especially to those with raised nanostructures, represents a great challenge. Polymer-based supporting layers generally lead to organic residues, while graphene transfer using alternative supporting materials like paraffin suffers from breaking and thus limits the transfer area. We demonstrated an improved poly(methyl methacrylate) (PMMA)/paraffin double layer, enabling the large-area transfer of graphene with high cleanliness and high coverage (81%) onto gold nanopyramid (AuNP)-structured substrates. The impact of supporting layers including single PMMA or paraffin and mixed PMMA/paraffin was clarified. The properties of graphene on AuNPs were theoretically and experimentally examined in detail. Raman spectra show a polarization-dependent D peak due to the folding of large-curvature graphene. The graphene on AuNPs shows a slightly tensile strain and provides extra surface-enhanced Raman scattering (SERS) with an enhancement factor of ∼20 times. These findings open a pathway to extend the applications of transferred graphene on raised nanostructures in many fields, such as SERS detection, catalysis, biosensors, light-emitting diodes, solar cells, and advanced transparent conductors.

Conventional glassy carbon electrodes (GCE) cannot meet the requirements of future electrodes for wider use due to low conductivity, high cost, non-portability, and lack of flexibility. Therefore, cost-effective and wearable electrode enabling rapid and versatile molecule detection is becoming important, especially with the ever-increasing demand for health monitoring and point-of-care diagnosis. Graphene is considered as an ideal electrode due to its excellent physicochemical properties. Here, we prepare graphene film with ultra-high conductivity and customize the 3-electrode system via a facile and highly controllable laser engraving approach. Benefiting from the ultra-high conductivity (5.65 × 105 Sm−1), the 3-electrode system can be used as multifunctional electrode for direct detection of dopamine (DA) and enzyme-based detection of glucose without further metal deposition. The dynamic ranges from 1–200 µM to 0.5–8.0 mM were observed for DA and glucose, respectively, with a limit of detection (LOD) of 0.6 µM and 0.41 mM. Overall, the excellent target detection capability caused by the ultra-high conductivity and ease modification of graphene films, together with their superb mechanical properties and ease of mass-produced, provides clear potential not only for replacing GCE for various electrochemical studies but also for the development of portable and highperformance electrochemical wearable medical devices.

A novel microfiber-like biohydrogel was fabricated by a facile approach relying on electroactive bacteria-induced graphene oxide reduction and confined self-assembly in a capillary tube. The microfiber-like biohydrogel (d = ∼1 mm) embedded high-density living cells and activated efficient electron exchange between cells and the conductive graphene network. Further, a miniature whole-cell electrochemical biosensing system was developed and applied for fumarate detection under −0.6 V (vs Ag/AgCl) applied potential. Taking advantage of its small size, high local cell density, and excellent electron exchange, this microfiber-like biohydrogel-based sensing system reached a linear calibration curve (R2 = 0.999) ranging from 1 nM to 10 mM. The limit of detection obtained was 0.60 nM, which was over 1300 times lower than a traditional biosensor for fumarate detection in 0.2 μL microdroplets. This work opened a new dimension for miniature whole-cell electrochemical sensing system design, which provided the possibility for bioelectrochemical detection in small volumes or three-dimensional local detection at high spatial resolutions.

Tracking genomic sequences as microbial biomarkers in wastewater has been used to determine community prevalence of infectious diseases, contributing to public health surveillance programs. Here we report upon a low-cost, rapid, and user-friendly paper microfluidic platform for SARS-CoV-2 and influenza detection, using a loop-mediated isothermal amplification (LAMP), with the signal read simply using a mobile phone camera. Sample-to-answer results were collected in -1. The device was subsequently used for on-site testing of SARS-CoV-2 in wastewater samples from four quarantine hotels at London Heathrow Airport, showing comparable results to those obtained using a gold-standard polymerase chain reaction assay, as reference. Our sensing platform, which enables rapid and localized wastewater surveillance and does not require the sample to be sent to a centralized laboratory, is potentially an important public health tool for a wide variety of future applications, in community settings.

Graphdiyne (GDY) has been considered as an appealing electrode material for electrochemical sensing because of its alkyne-rich structure and high degrees of π-conjugation, which shows great affinity to heavy metal ions and pollutant molecules via d−π and π–π interactions. However, the low surface area and poor conductivity of bulk GDY limit its electrochemical performance. Herein, a two-dimensional ultrathin GDY/graphene (GDY/G) nanostructure was synthesized and used as an electrode material for electrochemical sensing. Graphene plays the role of an epitaxy template for few-layered GDY growth and conductive layers. The formed few-layered GDY with a high surface area possesses abundant affinity sites toward heavy metal ions (Cd2+, Pb2+) and toxic molecules, for example, nitrobenzene and 4-nitrophenol, via d−π and π–π interactions, respectively. Moreover, hemin as a key part of the enzyme catalytic motif was immobilized on GDY/G via π–π interactions. The artificial enzyme mimic hemin/GDY/G-modified electrode exhibited promising ascorbic acid and uric acid detection performance with excellent sensitivity and selectivity, a good linear range, and reproducibility. More importantly, real sample detection and the feasibility of this electrochemical sensor as a wearable biosensor were demonstrated.

We prepared a biocompatible AuAg nanocages/graphdiyne @ polyethylene glycol (AuAg/GDY@PEG) composite. The combination of AuAg and GDY to obtain a synergistically enhanced photothermal effect, and the antibacterial effect of GDY and AuAg are used in combined anti-infective therapy. The in vitro antibacterial activity of AuAg/GDY@PEG was investigated, showing an impressive broad-spectrum antibacterial activity with the killing rate > 99.999%. Based on the photothermal conversion ability of AuAg/GDY@PEG, a simple photothermal immunoassay for pathogenic bacteria was successfully established. Sandwich immune response was performed on a microporous plate, the microplate containing the antibody binds specifically to the bacterium being tested, which then binds to the material with the antibody on its surface, and the signal was a change in temperature under 808 nm near-infrared light. The limit of detection (LOD) for S. typhimurium detection is 103 CFU mL−1, with a range of 103–107 CFU mL−1. This method is accurate, rapid and low-cost, which can be used for on-site detection of pathogenic bacteria in food.

Biosensors and nanoscale analytical tools have shown huge growth in literature in the past 20 years, with a large number of reports on the topic of ‘ultrasensitive’, ‘cost-effective’, and ‘early detection’ tools with a potential of ‘mass-production’ cited on the web of science. Yet none of these tools are commercially available in the market or practically viable for mass production and use in pandemic diseases such as coronavirus disease 2019 (COVID-19). In this context, we review the technological challenges and opportunities of current bio/chemical sensors and analytical tools by critically analyzing the bottlenecks which have hindered the implementation of advanced sensing technologies in pandemic diseases. We also describe in brief COVID-19 by comparing it with other pandemic strains such as that of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) for the identification of features that enable biosensing. Moreover, we discuss visualization and characterization tools that can potentially be used not only for sensing applications but also to assist in speeding up the drug discovery and vaccine development process. Furthermore, we discuss the emerging monitoring mechanism, namely wastewater-based epidemiology, for early warning of the outbreak, focusing on sensors for rapid and on-site analysis of SARS-CoV2 in sewage. To conclude, we provide holistic insights into challenges associated with the quick translation of sensing technologies, policies, ethical issues, technology adoption, and an overall outlook of the role of the sensing technologies in pandemics.

Paper 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.

The early diagnosis of active hepatitis C virus (HCV) infection remains a significant barrier to the treatment of the disease and to preventing the associated significant morbidity and mortality seen, worldwide. Current testing is delayed due to the high cost, long turnaround times and high expertise needed in centralised diagnostic laboratories. Here we demonstrate a user-friendly, low-cost pan-genotypic assay, based upon reverse transcriptase loop mediated isothermal amplification (RT-LAMP). We developed a prototype device for point-of-care use, comprising a LAMP amplification chamber and lateral flow nucleic acid detection strips, giving a visually-read, user-friendly result in, Current HCV nucleic acid-based diagnosis is largely performed in centralised laboratories. Here, the authors present a pan-genotypic RNA assay, based on reverse transcriptase loop mediated isothermal amplification and develop a low-cost prototype paper-based lateral flow device for point-of-care use, providing a visually read result within 40 min.

Infectious diseases are currently a significant cause of morbidity and mortality, with approximately 700 000 deaths each year worldwide.(1) Viruses, bacteria, and fungi have become increasingly resistant to antimicrobial agents, making antimicrobial resistance (AMR) one of the biggest global health challenges humanity has had to face. Recent reports have highlighted the role pandemics may play in exacerbating AMR through the increased use of disinfectants, alcohol-based hand sanitizers, and antiseptic hand wash.(2) Evidence of antibiotic mis-prescribing in hospitalised COVID-19 patients has also been reported, asking a pandemic-induced spike in AMR. Ultimately, the fate of antimicrobial agents and resulting resistant microorganisms is they are discarded into wastewater, entering the environment as sewage, sludge, and treated wastewater. This results in opportunities for further mutation and horizontal gene transfer (HGT).

Environmental 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.

Mercury (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.

Graphdiyne quantum dots (GDQDs) have attracted increasing attentions due to its unique electronic, optical, and electrochemical properties. However, the low conductivity and quantum yield of GDQDs limit their application. Here, nitrogen-doped graphdiyne dots (N-GDQDs) are firstly synthesized by a simple, friendly and one-step hydrothermal method. The N-GDQDs show a maximum emission at 410 nm under the excitation wavelength of 319 nm. The doping N modifies the surface defect of N-GDQDs and further greatly improves their quantum yield (from 14.6% to 48.6%). In addition, the doping N induces a strong electron transport ability and good conductivity of N-GDQDs. Subsequently, the prepared N-GDQDs are used for constructing an optical-electrochemical nanosensor for sensitive and selective detection of dopamine (DA). DA can quench the fluorescence of N-GDQDs by forming a ground-state non-fluorescent complex between phenoxy anions (in PBS solution) in DA and pyridinic N sites of N-GDQDs, which leads to a highly sensitive and selective detection of DA with a limit of detection (LOD) of 0.14 μM and a linear range of 0.32–500 μM. In the electrochemical detection, DA can be oxidized to DA-quinone under the electric field through N-GDQDs/GCE, which shows a big affinity to N-GDQDs. The LOD for DA is 0.02 μM with a linear range of 0.05–240 μM. Finally, the spiked application for DA detection in human serum samples is investigated, the results show that the method has high accuracy. Our work provides a new carbon quantum dots based sensing platform, which shows great potential in practical application.

The 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.

Antimicrobial resistance (AMR) in the environment is a global concern for public health and recent studies have shown that various soil pollutants (e.g. heavy metals, petroleum hydrocarbons) can cause the emergence of antibiotic-resistant bacteria and antibiotic-resistance genes in the soil. This emergence of AMR in soil is therefore prompting the research community for the development of rapid and real-time monitoring tools to better understand the source, fate and transfer pathway of AMR in contaminated soils. In this respect, the recent development of rapid sensors-based methods has been critically reviewed. The analytical performance of each sensing technique along with their advantages and limitations is further discussed to inform future development needs for the next generation sensors that would allow rapid and multiplexed detection of AMR in contaminated soils. By doing so, it would assist the decision making during remediation project and provide crucial insights into the risk assessment for contaminated sites.

Public 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.

Significance Populations living in remote rural communities would benefit from rapid, highly sensitive molecular, DNA-based diagnostics to inform the correct and timely treatment of infectious diseases. Such information is also becoming increasingly relevant in global efforts for disease elimination, where the testing of asymptomatic patients is now seen as being important for the identification of disease reservoirs. However, healthcare workers face practical and logistical problems in the implementation of such tests, which often involve complex instrumentation and centralized laboratories. Here we describe innovations in paper microfluidics that enable low-cost, multiplexed DNA-based diagnostics for malaria, delivered, in a first-in-human study, in schools in rural Uganda., Rapid, low-cost, species-specific diagnosis, based upon DNA testing, is becoming important in the treatment of patients with infectious diseases. Here, we demonstrate an innovation that uses origami to enable multiplexed, sensitive assays that rival polymerase chain reactions (PCR) laboratory assays and provide high-quality, fast precision diagnostics for malaria. The paper-based microfluidic technology proposed here combines vertical flow sample-processing steps, including paper folding for whole-blood sample preparation, with an isothermal amplification and a lateral flow detection, incorporating a simple visualization system. Studies were performed in village schools in Uganda with individual diagnoses being completed in

We describe a novel biosensing strategy for sensitive detection of methylamphetamine (MAMP) based on surface enhanced Raman scattering (SERS) by the mediation of spacing between 4-mercaptobenzoic acid (4-MBA) labeled Au@Ag core-shell nanoparticles (Au@Ag). To achieve a favorable SERS substrate, Au@Ag shell-core nanoparticle was synthesized with seeds growth method and well characterized by SEM, TEM and UV–vis spectrometer. The uniform Au@Ag shows an excellent dispersion ability for SERS detection. Under the optimized conditions, the novel biosensor shows a good logarithm linear correlation with the concentration of MAMP ranging from 0.5 ppb to 40 ppb (R2 = 0.986), with a limit of detection at 0.16 ppb of MAMP (3σ). Furthermore, our biosensors hold an excellent selectivity, demonstrated by the negligible interference from the detection of other illicit drugs and metabolites. The concentrations determined with our biosensor from spiked MAMP in human urine sample fell within the same range with the results from mass spectrometry. This indicates that our sensor has a clear potential for the rapid detection of illicit drug in real samples.

Wastewater-based epidemiology (WBE) is a powerful technique for monitoring illicit drugs of abuse in the community. Here, we report upon a surface-enhanced Raman spectroscopy (SERS) sensor for the sensitive and selective detection of methamphetamine based upon 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-shells (Au@Ag) gave strong SERS signalling, enabling us to evaluate the community-wide prevalence of methamphetamine in wastewater treatment plants within Beijing. We show that, when normalized for the daily flow of the wastewater treatment plants and for population density, higher mass loads of drugs are generally found in sewage influent from urban areas, implying greater local methamphetamine usage than that in less populated areas. The user-friendly and disposable paper sensors 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.

For in-situ disease markers detection, point-of-care (POC) diagnosis has great advantages in speed and cost compared with traditional techniques. The rapid diagnosis, prognosis, and surveillance of diseases can significantly reduce disease-related mortality and trauma. Therefore, increasing attention has been paid to the POC diagnosis devices due to their excellent diagnosis speed and portability. Over the past ten years, paper-based microfluidic aptasensors have emerged as a class of critical POC diagnosis devices and various aptasensors have been proposed to detect various disease markers. However, most aptasensors need further improvement before they can actually enter the market and be widely used. There is thus an urgent need to sort out the key points of preparing the aptasensors and the direction that needs to be invested in. This review summarizes the representative articles in the development of paper-based microfluidic aptasensors. These works can be divided into paper-based optical aptasensors and paper-based electrochemical aptasensors according to their output signals. Significant focus is applied to these works according to the following three parts: (1) The ingenious design of device structure; (2) Application and synthesis of nanomaterial; (3) The detection principle of the proposed aptasensor. This is a detailed and comprehensive review of paper-based microfluidic aptasensors. The accomplishments and shortcomings of the current aptasensors are outlined, the development direction and the future prospective are given. It is hoped that the research in this review can provide a reference for further development of more advanced, more effective paper-based microfluidic aptasensors for POC disease markers diagnosis.

Cadmium (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.

The 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., Graphical abstract Image 1, Highlights • The concept of wastewater-based drug epidemiology (WBE) was outlined. • The recent advances of nanomaterial-based aptasensors for illicit drugs detection are described, focusing on optical and electrochemical strategies. • The emerging DNA technology are discussed for drug detection as well as engineering of aptasensors for portable assay. • The feasibility of illicit drug aptasensors for WBE are discussed. • The future trends and our insights on aptasensors for illicit drug are provided.

In this work, an electrochemical paper-based aptasensor was fabricated for label-free and ultrasensitive detection of epidermal growth factor receptor (EGFR) by employing anti-EGFR aptamers as the bio-recognition element. The device used the concept of paper-folding, or origami, to serve as a valve between sample introduction and detection, so reducing sampling volumes and improving operation convenience. Amino-functionalized graphene (NH2-GO)/thionine (THI)/gold particle (AuNP) nanocomposites were used to modify the working electrode not only to generate the electrochemical signals, but also to provide an environment conducive to aptamer immobilization. Electrochemical characterization revealed that the formation of an insulating aptamer–antigen immunocomplex would hinder electron transfer from the sample medium to the working electrode, thus resulting in a lower signal. The experimental results showed that the proposed aptasensor exhibited a linear range from 0.05 to 200 ngmL−1 (R2 = 0.989) and a detection limit of 5 pgmL−1 for EGFR. The analytical reliability of the proposed paper-based aptasensor was further investigated by analyzing serum samples, showing good agreement with the gold-standard enzyme-linked immunosorbent assay. A low-cost electrochemical paper-based sensor has been developed for the highly sensitive detection of epidermal growth factor receptor (EGFR). EGFR normally activates relevant genes, resulting in cell division and proliferation, although its overexpression has been observed in some forms of cancer. There is thus a growing interest in determining EGFR levels as a biomarker for early-stage disease diagnosis. A team headed by Xinxia Cai at the Chinese Academy of Sciences, Beijing succeeded in developing a biosensor for EGFR by combining the screen printing of a graphene-modified nanocomposite electrode onto an origami paper-folding for enabling microfluidic reagent and sample processing. The device gave a low detection limit and linear responses across a wide range of EGFR concentrations in human serum (electronic input values). The authors believe that their device can be easily adapted to other soluble biomarkers and that it has potential for use as a handheld instrument as point-of-care testing in early diagnosis and efficacy evaluation of cancer.

A 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.

This 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.

Mercury (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 (