Enhanced electrocatalytic activity in MOFs-derived 3D hollow NiCo-LDH nanocages decorated porous biochar for simultaneously ultra-sensitive electrochemical sensing of Cu2+ and Hg2.

Layered double hydroxides (LDHs) have attracted significant attention due to their compositional and structural flexibility. However, it is challenging but meaningful to design and fabricate hierarchical mixed-dimensional LDHs with synergistic effects to increase the electrical conductivity of LDHs and promote the intrinsic activity. Herein, 3D hollow NiCo-LDH nanocages decorated porous biochar (3D NiCo-LDH/PBC) has been synthesized by using ZIF-67 as precursor, which was utilized for constructing electrochemical sensing platform to realize simultaneous determination of Cu2+ and Hg2+. The 3D NiCo-LDH/PBC possessed the characteristics of hollow material and three-dimensional porous material, revealing a larger surface area, more exposed active sites, and faster electron transfer, which is beneficial to enhancing its electrochemical performance. Consequently, the developed sensor displayed good performance for simultaneously detecting Cu2+ and Hg2+ with ultra-low limit of detection (LOD) of 0.03 µg L-1 and 0.03 µg L-1, respectively. The proposed sensor also demonstrated excellent stability, repeatability and reproducibility. Furthermore, the sensor can be successfully used for the electrochemical analysis of Cu2+ and Hg2+ in lake water sample with satisfactory recovery, which is of great feasibility for practical application.

Water-Stable Ln-MOF as a multi-emitting luminescent sensor for the detection of metal ions and pharmaceuticals.

The development of innovative multi-emission sensors for the rapid and accurate detection of contaminants is both vital and challenging. In this study, utilizing two rigid ligands (H3ICA and H4BTEC), a series of water-stable bimetallic organic frameworks (EuTb-MOFs) were synthesized. Luminescent investigations have revealed that EuTb-MOF-1 exhibits prominent multiple emission peaks, attributed to the distinctive fluorescence characteristics of Eu(III) and Tb(III) ions. Therefore, EuTb-MOF-1 efficiently recognized various metal ions and pharmaceutical compounds through 2D decoded maps. Fe3+ and Pb2+ exhibited significant quenching effects on the luminescence of EuTb-MOF-1, which were attributed to the internal filtering effect and the interaction between Lewis basic sites within EuTb-MOF-1 and Pb2+ ions, respectively. Furthermore, EuTb-MOF-1 demonstrated high sensitivity to sulfonamide antibiotics, with detection limits of 0.037 µM for SMZ and 0.041 µM for SDZ, respectively. In addition, EuTb-MOF-1 was immobilized to prepare MOF-based test strips, enabling direct visual detection of sulfonamides as a portable sensor. With excellent water stability, multi-responsive recognition capabilities, and high sensitivity to specific analytes, EuTb-MOF-1 is a promising candidate for environmental contaminant detection in aquatic systems.

Heavy metal ion sensing strategies using fluorophores for environmental remediation.

The main aim of this review is to provide an extensive summary of the latest advances within the emerging research area focused on detecting heavy metal ion pollution, particularly sensing strategies. The review explores various heavy metal ion detection approaches, encompassing spectrometry, electrochemical methods, and optical techniques. Numerous initiatives have been undertaken in recent times in response to the increasing demand for fast, sensitive, and selective sensors. Notably, fluorescent sensors have acquired prominence owing to the numerous advantages such as outstanding specificity, reversibility, and sensitivity. Further, it also explores the discussion of various nanomaterials employed in sensing heavy metal ions. In this regard, the exclusive emphasis is placed on fluorescent nanomaterials based on organic dyes, quantum dots, and fluorescent aptasensors for metal ion removal from aqueous systems to identify the destiny of dangerous heavy metal ions in clean circumstances.

Evaluation of the enzymatic properties of DNA (cytosine-5)-methyltransferase M.ApeKI from archaea in the presence of metal ions.

We previously identified M.ApeKI from Aeropyum pernix K1 as a highly thermostable DNA (cytosine-5)-methyltransferase. M.ApeKI uses the type II restriction-modification system (R-M system), among the best-studied R-M systems. Although endonucleases generally utilize Mg (II) as a cofactor, several reports have shown that MTases exhibit different reactions in the presence of metal ions. This study aim was to evaluate the enzymatic properties of DNA (cytosine-5)-methyltransferase M.ApeKI from archaea in the presence of metal ions. We evaluated the influence of metal ions on the catalytic activity and DNA binding of M.ApeKI. The catalytic activity was inhibited by Cu (II), Mg (II), Mn (II), and Zn (II), each at 5 mM. DNA binding was more strongly inhibited by 5 mM Cu (II) and 10 mM Zn (II). To our knowledge, this is the first report showing that DNA binding of typeII MTase is inhibited by metal ions.

Concurrent manipulation of competitive mechanisms to construct glutathione-stabilized gold nanocluster-based dual-channel molecular classifier for metal ions detection and information steganography.

Understanding charge transport in metal ion-mediated glutathione-stabilized gold nanoclusters (GSH-Au NCs) has proved difficult due to the presence of various competitive mechanisms, such as electron transfer (ET) and aggregation induction effect (AIE). In this paper, we present a dual-channel fluorescence (FL) and second-order Rayleigh scattering (SRS) sensing method for high-throughput classification of metal ions, relying on the competition between ET and AIE using GSH-Au NCs. The SRS signals show significant enhancement when Pb2+, Ag+, Al3+, Cu2+, Fe3+, and Hg2+ are present, as a result of the aggregation of GSH-Au NCs. Notably, the fluorescence signal exhibits the opposite trend. The FL intensities of GSH-Au NCs are enhanced by Pb2+, Ag+, and Al3+ through the AIE mechanism, while they are quenched by Cu2+, Fe3+, and Hg2+, which is dominated by the ET mechanism. By employing principal component analysis and hierarchical cluster analysis, these signals are transformed into unique fingerprints and Euclidean distances, respectively, enabling successful distinction of six metal ions and their mixtures with a low detection limit of 30 nM. This new strategy has successfully addressed interference from impurities in the testing of real water samples, demonstrating its strong ability to detect multiple metal ions. Impressively, we have achieved molecular cryptosteganography, which involves encoding, storing, and concealing information by transforming the selective response of GSH-Au NCs to binary strings. This research is anticipated to advance utilization of nanomaterials in logic sensing and information safety, bridging the gap between molecular sensors and information systems.

Synthesis, application and molecular docking of modified cellulose with diaminoguanidine as complexing agent for selective separation of Cu (II), Cd (II) and Hg (II) ions from alum sample.

A new modified cellulose with diaminoguanidine (Cel-Gua) synthesized for specific recovery of Cu (II), Cd (II), and Hg (II) from the alum sample. Cellulose was silanized by 3-chloropropyltrimethoxysilane and then was modified with diaminoguanidine to obtain N-donor chelating fibers. Fourier transform-infrared spectroscopy, scanning electron microscopy, X-ray diffraction, zeta potential, electrons disperse X-ray analysis, elemental analyses (C, H and N), and thermogravimetric analysis were used for characterization. Factors influencing the adsorption were thoroughly examined. Under the optimal conditions, the Cel-Gua sorbent displayed maximum adsorption capacities of 94.33, 112.10 and 95.78 mg/g for Cu (II), Cd (II), and Hg (II), respectively. The sorption process of metal ions is equipped by kinetic model PSO and Langmuir adsorption isotherm. The calculated thermodynamic variables confirmed that the adsorption of Cu (II), Cd (II) and Hg (II) by Cel-Gua sorbent is a spontaneous and exothermic process. In our study, we used the molecular operating environment software to conduct molecular docking simulations on the Cel-Gua compound. The results of the docking simulations showed that the Cel-Gua compound displayed greater potency and a stronger affinity for the Avr2 effector protein derived from Fusarium oxysporum, a fungal plant pathogen (code 5OD4). The adsorbent was stable for 7 cycles, thus allowing its safe reutilization.

Preparation of 6-Amino-N-hydroxyhexanamide-Modified Porous Chelating Resin for Adsorption of Heavy Metal Ions.

The pollution of water bodies by heavy metal ions has recently become a global concern. In this experiment, a novel chelating resin, D851-6-AHHA, was synthesized by grafting 6-amino-N-hydroxyhexanamide (6-AHHA) onto the (-CH2N-(CH2COOH)2) group of the D851 resin, which contained a hydroxamic acid group, amide group, and some carboxyl groups. This resin was developed for the purpose of removing heavy metal ions, such as Cr(III) and Pb(II), from water. The findings from static adsorption experiments demonstrated the remarkable adsorption effectiveness of D851-6-AHHA resin towards Cr(III) and Pb(II). Specifically, the maximum adsorption capacities for Cr(III) and Pb(II) were determined to be 91.50 mg/g and 611.92 mg/g, respectively. Furthermore, the adsorption kinetics of heavy metal ions by D851-6-AHHA resin followed the quasi-second-order kinetic model, while the adsorption isotherms followed the Langmuir model. These findings suggest that the adsorption process was characterized by monolayer chemisorption. The adsorption mechanism of D851-6-AHHA resin was comprehensively investigated through SEM, XRD, FT-IR, and XPS analyses, revealing a high efficiency of D851-6-AHHA resin in adsorbing Cr(III) and Pb(II). Specifically, the (-C(=O)NHOH) group exhibited a notable affinity for Cr(III) and Pb(II), forming stable multi-elemental ring structures with them. Additionally, dynamic adsorption experiments conducted using fixed-bed setups further validated the effectiveness of D851-6-AHHA resin in removing heavy metal ions from aqueous solutions. In conclusion, the experimental findings underscored the efficacy of D851-6-AHHA resin as a highly efficient adsorbent for remediating water bodies contaminated by heavy metal ions.

Controlled release of manganese and magnesium ions by microsphere-encapsulated hydrogel enhances cancer immunotherapy.

Despite the considerable potential of immune checkpoint blockade (ICB) therapy in treating various cancer types, it faces several challenges, of which the constrained objective response rate and relatively short duration of response observed in patients with cancer are the most important. This study introduces an injectable temperature-sensitive hydrogel, Pluronic F-127 (PF-127)@MnCl2/ alginate microspheres (ALG-MS)@MgCl2, that enhances the therapeutic efficacy of programmed cell death-ligand 1 (PD-L1) in cancer cells. The hydrogel material used in this study facilitated the rapid release of a significant amount of manganese ions (Mn2+) and the gradual and sustained release of magnesium ions (Mg2+) within the tumor microenvironment. This staged release profile promotes an immune microenvironment conducive to the cytotoxicity of CD8+ T cells and natural killer cells, thereby enhancing the efficacy of ICB therapy. Furthermore, the PF-127@MnCl2/ALG-MS@MgCl2 composite hydrogel exhibits the ability to convert drug-resistant tumor ("cold tumor") with a low PD-L1 response to a "hot tumor" with a high PD-L1 response. In summary, the PF-127@MnCl2/ALG-MS@MgCl2 hydrogel manipulates the immune microenvironment through the precise discharge of Mg2+ and Mn2+, thus, augmenting the efficacy of ICB therapy.

Metalloproteins structural and functional insights into immunological patterns.

Metalloproteins play a crucial role in regulating different aspects of the immune system in humans. They have various functions in immunity, including recognizing and presenting antigens, aiding in the movement and effectiveness of immune cells, and facilitating interactions between the host and pathogens. Understanding how these proteins work can help us develop new methods to control the immune response in different diseases. Metalloproteins contain metal ions in their structure, which allows them to perform these diverse functions. They encompass a wide range of enzymes, signaling molecules, and structural proteins that utilize metal ions as cofactors for their activities. Examples of metalloproteins include superoxide dismutase, catalase, and metalloproteases, which regulate oxidative stress, inflammation, and tissue remodelling processes associated with immune activation. By studying their functions and the effects of their dysfunction, researchers can develop strategies to improve immune function and combat various diseases. This review explores the diverse functions of metalloproteins in immune processes, highlighting their significance in both health and disease.

Hybrid method integrating adsorption and chemical precipitation of heavy metal ions on polymeric fiber surfaces for highly efficient water purification.

A lot of research has been focused on increasing the specific surface area of adsorbents over a long period of time to remove heavy metal ions from wastewater using the adsorbent. However, porous adsorbents with high specific surface area have demonstrated drawbacks in water purification processes, such as high pressure drop and limitations in the adsorption capacity of heavy metal ions. In recent years, a mechanism-based convergence method involving adsorption/chemical precipitation has emerged as a promising strategy to surmount the constraints associated with porous adsorbents. The mechanism involves amine groups on chelating fibers dissociating OH- ions from water molecules, thereby raising the pH near the fibers. This elevated pH promotes the crystallization of heavy metal ions on the fiber surfaces. The removal of heavy metal ions proceeds through a sequence of adsorption and chemical precipitation processes. An adsorbent based on chelating fibers, integrating adsorption technology with chemical precipitation, demonstrates superior performance in removing significant quantities of heavy metal ions (ca. 1000-2000 mg/g for Cd2+, Cu2+ and Pb2+) when compared to developed porous adsorbents (ca. 50-760 mg/g for same ions). This review paper introduces advanced polymer fibers endowed with the capability to integrate hybrid technology, delves into the mechanism of hybrid technology, and examines its application in process technology for the effective removal of heavy metal ions. The versatility of these advanced fibers extends far beyond the removal of heavy metal ions in water treatment, making them poised to garner significant attention from researchers across diverse fields due to their broad range of potential applications. After further processes involving the removal of templates from chelating polymeric fibers used as supports and the reduction of precipitated heavy metal oxide crystals, the resulting heavy metal crystals can exhibit thin walls and well-interconnected porous structures, suitable for catalytic applications.

Impact of COVID-19 on temporal trends and health risks of urinary metal concentrations among residents of Guangzhou, China.

Long-term biomonitoring of urinary metal ions is an essential tool for the epidemiological assessment of chronic exposure levels, enabling us to track changes in metal exposure over time and better understand its health implications. In this study, we evaluated the temporal trends of urinary metal ions among 1962 residents of Guangzhou, China, from 2018 to 2022. The total metal ion concentrations in the urine of the population did not change significantly between 2018 and 2019. With the onset of the COVID-19 pandemic in 2020, urinary total metal ion concentrations began to decline dramatically, reaching their lowest level in 2021. A rebound in concentrations was observed in 2022, which returned to the initial levels observed in 2018. Urine chromium and cadmium concentrations peaked in 2020, while urinary lead levels were the highest in 2021, and urinary nickel concentrations were the highest in 2022. Males consistently displayed higher urinary concentrations of lead and arsenic throughout each year of the study. Furthermore, minors consistently had higher urinary nickel levels than adults, whereas adults consistently had higher urinary cadmium concentrations than minors. Cluster analyses were conducted annually on urinary metal ions to examine the differences in their distribution and to evaluate changes in metal exposure patterns over time. The Monte Carlo simulations indicate that the whole population exhibits a high non-carcinogenic risk from arsenic exposure and significant carcinogenic risks associated with exposure to nickel, arsenic, chromium, and cadmium. The next two years were predicted by a gray prediction model, and the results are tested using mean absolute percentage error which demonstrating high accuracy.

Inhibiting Voltage Decay in Li-Rich Layered Oxide Cathode: From O3-Type to O2-Type Structural Design.

Li-rich layered oxide (LRLO) cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density, which combines cationic and anionic redox activities. However, continuous voltage decay during cycling remains the primary obstacle for practical applications, which has yet to be fundamentally addressed. It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions, which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions. Recently, constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay. In this review, the relationship between voltage decay and structural evolution is systematically elucidated. Strategies to suppress voltage decay are systematically summarized. Additionally, the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed. Unfortunately, the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles. Herein, the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored, while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.

Effective and green in-situ remediation strategies based on TEMPO-nanocellulose/lignin/MIL-100(Fe) hydrogel nanocomposite adsorbent for lead and copper in agricultural soils.

Hydrogel adsorbents are promising tools for reducing heavy metals' bioavailability in contaminated soil. However, their practical feasibility remains limited by the low stability, inefficient removal efficiency, and potential secondary pollution. Optimizing the adsorption operation and the functional properties of hydrogel adsorbents could eliminate this method's drawbacks. Herein, three innovative in-situ remediation strategies for Pb/Cu-contaminated soil were adopted based on the concept of novel TEMPO-cellulose (TO-NFCs)/lignin/acrylamide@MIL-100(Fe) nanocomposite hydrogel adsorbent (NCLMH). Characteristic analyses revealed ideal Pb/Cu adsorption mechanisms by swelling, complexation, electrical attraction, and ion exchange via carboxyl/hydroxyl/carbonyl groups and unsaturated Fe(III) sites on ANCMH besides FeOOH formation. The highest maximum theoretical adsorption capacities of Pb(II) and Cu(II) on ANCMH were 416.39 and 133.98 mg/g, under pH 6.5, governed by pseudo-second-order/Freundlich models. Greenhouse pot experiments with contaminated soils amended with two-depth layers of 0.5% NCLMHs (SA@NCLMH) displayed a decline in Pb and Cu bioavailability up to 85.9% and 74.5% within 45 d. Soil column studies simulating continuous water soil flushing coupled with NCLMH layers, instead of conventional extractant fluids, and connected to NCLMH-sand column as purification unit (CF@NCLMH) achieved higher removal rates for Pb, and Cu of 89.5% and 77.2% within 24 h. Alternatively, conducting multiple-pulse soil flushing mode (MF@NCLMH) gained the highest Pb and Cu removal of 96.5% and 85.4%, as the water flushing-stop flux events allowed adequate water movement/residence period, promoting Pb/Cu desorption-adsorption from soil to NCLMH. Also, the NCLMH-sand column conducting and easy separation of the stable/reusable NCLMHs prevented the potential secondary pollution. Interestingly, the three remediated soils reached the corresponding regulation of the permissible limits for Pb and Cu residential scenarios in medium-to-heavily agricultural polluted soils, alleviating the Pb/Cu bioaccumulation and phytotoxicity symptoms in cultivated wheat, especially after MF@NCLMH treatment. This study introduces promising alternative remediation strategies with high sustainability and feasibility in acidic-to-neutral heavy metal-contaminated agricultural soil.

Exploring the central region of amylin and its analogs aggregation: the influence of metal ions and residue substitutions.

Human amylin (hIAPP) is found in the form of amyloid deposits within the pancreatic cells of nearly all patients diagnosed with type 2 diabetes mellitus (T2DM). However, rat amylin (rIAPP) and pramlintide - hIAPP analogs - are both non-toxic and non-amyloidogenic. Their primary sequences exhibit only slight variations in a few amino acid residues, primarily concentrated in the central region, spanning residues 20 to 29. This inspired us to study this fragment and investigate the impact on the aggregation properties of substituting residues within the central region of amylin and its analogs. Six fragments derived from amylin have undergone comprehensive testing against various metal ions by implementing a range of analytical techniques, including Nuclear Magnetic Resonance (NMR) spectroscopy, Thioflavin T (ThT) assays, Atomic Force Microscopy (AFM), and cytotoxicity assays. These methodologies serve to provide a thorough understanding of how the substitutions and interactions with metal ions impact the aggregation behavior of amylin and its analogs.

A novel composite electrode with multiple pore structures for efficient treatment of heavy metal ions in capacitive deionization.

Multiple porous carbon materials have great promise and potential in the capacitive deionization (CDI) field. Specific surface area (SSA), pore size distribution, and preparation method of CDI electrode materials are essential for the treatment of heavy metal ions. In this work, PPy composited porous carbon electrodes (hypercrosslinked polymers/polypyrrole, HCPs/PPy) were obtained by one-step crosslinked carbonization preparation and electro-deposition. The diverse pore structure gives the composite electrode a large SSA and excellent adsorption performance. HCPs/PPy-4 gives a high SSA of 251.26 m2/g. In the CDI process, the adsorption capacity of HCPs/PPy-4 for Fe3+, Cu2+, Pb2+, and Ag+ is 20.69 mg/g, 37.81 mg/g, 26.86 mg/g, and 40.95 mg/g. The negative electrode recoveries for the adsorption of the four ions were reached 81.2%, 89.2%, 85.5%, and 100%, respectively. It indicates that HCPs/PPy is a novel and potentially porous carbon electrode for high-performance CDI.

Heavy-Metal Ions Removal and Iodine Capture by Terpyridine Covalent Organic Frameworks.

Porous materials are excellent candidates for water remediation in environmental issues. However, it is still a key challenge to design efficient adsorbents for rapid water purification from various heavy metal ions-contaminated wastewater in one step. Here, two robust nitrogen-rich covalent organic frameworks (COFs) bearing terpyridine units on the pore walls by a "bottom-up" strategy are reported. Benefitting from the strong chelation interaction between the terpyridine units and various heavy metal ions, these two terpyridine COFs show excellent removal efficiency and capability for Pb2+, Hg2+, Cu2+, Ag+, Cd2+, Ni2+, and Cr3+ from water. These COFs are shown to remove such heavy metal ions with >90% of contents at one time after the aqueous metal ions mixture is passed through the COF filter. The nitrogen-rich features of the COFs also endow them with the capability of capturing iodine vapors, offering the terpyridine COFs the potential for environmental remediation applications.

Inhibit-AND logic gate enabled versatile BoF-AgNPs as ultrasensitive and selective nanoprobe for Mn(II) ions and nanocatalyst for rapid MB decoloration.

There is great interest in fabricating devices that can detect and remove water pollutants, especially heavy metal ions and dyes from wastewater, to promote sustainable water use. In this study, an extract of Borassus flabellifer leaves (BoF-LE) was used to synthesize silver nanoparticles (BoF-AgNPs), with the BoF-LE serving as a reducing and capping agent. The sensitivity and selectivity of BoF-AgNPs for Mn(II) ions were tested by comparing with the control sample and other competent metal ions. Our results showed that BoF-AgNPs are extremely sensitive and selective in detecting Mn(II) ions, with a detection limit of 0.3 ppb. HR-TEM, UV-Vis spectroscopy, and DLS investigations were used to confirm that BoF-AgNPs detect Mn(II) ions by an aggregation-based mechanism. Additionally, it was found that BoF-AgNPs are effective in rapidly decolorizing MB dye, as demonstrated by their ability to decolorize MB by 92.66% within 7 min. This study is the first to report successful synthesis of BoF-AgNPs and their two applications, which are enabled with an Inhibit-AND logic gate. Using BoF-AgNPs to detect and degrade water pollutants may promote sustainable water use.

Antibacterial effect of the metal nanocomposite on Escherichia coli.

Ag nanocomposites (NAs) have been found to induce irreversible harm to pathogenic bacteria, however, NAs tend to aggregate easily when used alone. These nanocomposites also show increased toxicity and their underlying antibacterial mechanism is still unknown. In short, practical applications of NA materials face the following obstacles: elucidating the mechanism of antibacterial action, reducing cytotoxicity to body cells, and enhancing antibacterial activity. This study synthesized a core-shell structured ZnFe2O4 @Cu-ZIF-8 @Ag (FUA) nanocomposite with high antibacterial activity and low cytotoxicity. The nanocomposites achieved a 99.99 % antibacterial rate against Escherichia coli (E. coli) and tetracycline-resistant E. coli (T - E. coli), in under 20 min at 100 µg/mL. The nanocomposites were able to inactivate E. coli due to the gradual release of Cu2+, Zn2+, and Ag+ ions, which synergistically form •OH from FUA in an aerobic environment. The presence of •OH has significant effects on the antibacterial activity. The released metal ions combine with •OH to cause damage to the bacterial cell wall, resulting in the leakage of electrolytes and ions. Moreover, in comparison to NA, the toxicity of FUA is considerably reduced. This study is expected to inspire the development of other silver-based nanocomposite materials for the inactivation of drug-resistant bacteria.

Application Prospect of Ion-Imprinted Polymers in Harmless Treatment of Heavy Metal Wastewater.

With the rapid development of industry, the discharge of heavy metal-containing wastewater poses a significant threat to aquatic and terrestrial environments as well as human health. This paper provides a brief introduction to the basic principles of ion-imprinted polymer preparation and focuses on the interaction between template ions and functional monomers. We summarized the current research status on typical heavy metal ions, such as Cu(II), Ni(II), Cd(II), Hg(II), Pb(II), and Cr(VI), as well as metalloid metal ions of the As and Sb classes. Furthermore, it discusses recent advances in multi-ion-imprinted polymers. Finally, the paper addresses the challenges faced by ion-imprinted technology and explores its prospects for application.

Single-atom nanozymes: Emerging talent for sensitive detection of heavy metals.

In recent years, the increasingly severe pollution of heavy metals has posed a significant threat to the environment and human safety. Heavy metal ions are highly non-biodegradable, with a tendency to accumulate through biomagnification. Consequently, accurate detection of heavy metal ions is of paramount importance. As a new type of synthetic nanomaterials, single-atom nanozymes (SANs) boast exceptional enzyme-like properties, setting them apart from natural enzymes. This unique feature affords SANs with a multitude of advantages such as dispersed active sites, low cost and variety of synthetic methods over natural enzymes, making them an enticing prospect for various applications in industrial, medical and biological fields. In this paper, we systematically summarize the synthetic methods and catalytic mechanisms of SANs. We also briefly review the analytical methods for heavy metal ions and present an overall overview of the research progress in recent years on the application of SANs in the detection of environmental heavy metal ions. Eventually, we propose the existing challenges and provide a vision for the future.