Nanozyme-Enabled Biomedical Diagnosis: Advances, Trends, and Challenges.

As nanoscale materials with the function of catalyzing substrates through enzymatic kinetics, nanozymes are regarded as potential alternatives to natural enzymes. Compared to protein-based enzymes, nanozymes exhibit attractive characteristics of low preparation cost, robust activity, flexible performance adjustment, and versatile functionalization. These advantages endow them with wide use from biochemical sensing and environmental remediation to medical theranostics. Especially in biomedical diagnosis, the feature of catalytic signal amplification provided by nanozymes makes them function as emerging labels for the detection of biomarkers and diseases, with rapid developments observed in recent years. To provide a comprehensive overview of recent progress made in this dynamic field, here an overview of biomedical diagnosis enabled by nanozymes is provided. This review first summarizes the synthesis of nanozyme materials and then discusses the main strategies applied to enhance their catalytic activity and specificity. Subsequently, representative utilization of nanozymes combined with biological elements in disease diagnosis is reviewed, including the detection of biomarkers related to metabolic, cardiovascular, nervous, and digestive diseases as well as cancers. Finally, some development trends in nanozyme-enabled biomedical diagnosis are highlighted, and corresponding challenges are also pointed out, aiming to inspire future efforts to further advance this promising field.

Nanozyme Metabolism Controls Air Pollution over an Atomic Potassium Cyano Site.

Increasing threats of air pollution prompt the design of air purification systems. As a promising initiative defense strategy, nanocatalysts are integrated to catalyze the detoxification of specific pollutants. However, it remains a grand challenge to tailor versatile nanocatalysts to cope with diverse pollutants in practice. Here, we report a nanozyme metabolism system to realize broad-spectrum protection from air pollution. Atomic K-modified carbon nitride featuring flavin oxidase-like and peroxidase-like activities was synthesized to initiate nanozyme metabolism. In situ experiments and theoretical investigations collectively show that K sites optimize the geometric and electronic structure of cyano sites for both enzyme-like activities. As a proof of concept, the nanozyme metabolism was applied to the mask against volatile organic compounds, persistent organic pollutants, reactive oxygen species, bacteria, and so on. Our finding provides a thought to tackle global air pollution and deepens the understanding of nanozyme metabolism.

Anisotropic Dual S-Scheme Heterojunctions Mimic Natural Photosynthetic System for Boosting Photoelectric Response.

The design of heterojunctions that mimic natural photosynthetic systems holds great promise for enhancing photoelectric response. However, the limited interfacial space charge layer (SCL) often fails to provide sufficient driving force for the directional migration of inner charge carriers. Drawing inspiration from the electron transport chain (ETC) in natural photosynthesis system, we developed a novel anisotropic dual S-scheme heterojunction artificial photosynthetic system composed of Bi2O3-BiOBr-AgI for the first time, with Bi2O3 and AgI selectively distributed along the bicrystal facets of BiOBr. Compared to traditional semiconductors, the anisotropic carrier migration in BiOBr overcomes the recombination resulting from thermodynamic diffusion, thereby establishing a potential ETC for the directional migration of inner charge carriers. Importantly, this pioneering bioinspired design overcomes the limitations imposed by the limited distribution of SCL in heterojunctions, resulting in a remarkable 55-fold enhancement in photoelectric performance. Leveraging the etching of thiols on Ag-based materials, this dual S-scheme heterojunction is further employed in the construction of photoelectrochemical sensors for the detection of acetylcholinesterase and organophosphorus pesticides.

3D-Printed Flexible Microfluidic Health Monitor for In Situ Sweat Analysis and Biomarker Detection.

Wearable sweat biosensors have shown great progress in noninvasive, in situ, and continuous health monitoring to demonstrate individuals' physiological states. Advances in novel nanomaterials and fabrication methods promise to usher in a new era of wearable biosensors. Here, we introduce a three-dimensional (3D)-printed flexible wearable health monitor fabricated through a unique one-step continuous manufacturing process with self-supporting microfluidic channels and novel single-atom catalyst-based bioassays for measuring the sweat rate and concentration of three biomarkers. Direct ink writing is adapted to print the microfluidic device with self-supporting structures to harvest human sweat, which eliminates the need for removing sacrificial supporting materials and addresses the contamination and sweat evaporation issues associated with traditional sampling methods. Additionally, the pick-and-place strategy is employed during the printing process to accurately integrate the bioassays, improving manufacturing efficiency. A single-atom catalyst is developed and utilized in colorimetric bioassays to improve sensitivity and accuracy. A feasibility study on human skin successfully demonstrates the functionality and reliability of our health monitor, generating reliable and quantitative in situ results of sweat rate, glucose, lactate, and uric acid concentrations during physical exercise.

Harmonizing Enzyme-like Cofactors to Boost Nanozyme Catalysis.

Engineering isolated metal sites resembling the primary coordination sphere of metallocofactors enables atomically dispersed materials as promising nanozymes. However, most existing nanozymes primarily focus on replicating specific metallocofactors while neglecting other supporting cofactors within active pockets, leading to reduced electron transfer (ET) efficiency and thus inferior catalytic performances. Herein, we report a metal-organic framework UiO-67 nanozyme with atomically dispersed iron sites, which involves multiple tailored enzyme-like nanocofactors that synergistically drive the ET process for enhanced peroxidase-like catalysis. Among them, the linker-coupled atomic iron site plays a critical role in substrate activation, while bare linkers and zirconia nodes facilitate the ET efficiency of intermediates. The synergy of three nanocofactors results in a 4.29-fold enhancement compared with the single effort of isolated metal site-based nanocofactor, holding promise in immunoassay for sensitive detection of chlorpyrifos. This finding opens a new way for designing high-performance nanozymes by harmonizing various nanocofactors at the atomic and molecular scale.

Effect of Phosphorus Modulation in Iron Single-Atom Catalysts for Peroxidase Mimicking.

Fe-N-C single-atom catalysts (SACs) exhibit excellent peroxidase (POD)-like catalytic activity, owing to their well-defined isolated iron active sites on the carbon substrate, which effectively mimic the structure of natural peroxidase's active center. To further meet the requirements of diverse biosensing applications, SAC POD-like activity still needs to be continuously enhanced. Herein, a phosphorus (P) heteroatom is introduced to boost the POD-like activity of Fe-N-C SACs. A 1D carbon nanowire (FeNCP/NW) catalyst with enriched Fe-N4 active sites is designed and synthesized, and P atoms are doped in the carbon matrix to affect the Fe center through long-range interaction. The experimental results show that the P-doping process can boost the POD-like activity more than the non-P-doped one, with excellent selectivity and stability. The mechanism analysis results show that the introduction of P into SAC can greatly enhance POD-like activity initially, but its effect becomes insignificant with increasing amount of P. As a proof of concept, FeNCP/NW is employed in an enzyme cascade platform for highly sensitive colorimetric detection of the neurotransmitter acetylcholine.

Influences of Cognitive Function and Depressive Symptoms on Pain Trajectories During the First Year Following Hip Fracture Surgery: A Prospective Cohort Study.

OBJECTIVES: The purposes of this study were to explore trajectories for patterns of postoperative pain intensity during the first year following hip fracture surgery and the relationships between pain trajectory groups, cognitive impairment, and depressive symptoms. DESIGN: A prospective cohort correlational study. SETTING AND PARTICIPANTS: A total of 325 patients aged 60 years or older who had received hip fracture surgery at a 3000-bed medical center in northern Taiwan from September 2012 to March 2020. METHODS: Data were collected before hospital discharge and at 1, 3, 6, and 12 months postdischarge. Pain intensity was measured using a numeric rating scale; cognitive function was measured with the Taiwan version of the Mini-Mental State Examination; and depressive symptoms were measured by the Geriatric Depression Scale-Short Form. Patients with similar postoperative pain trajectories were categorized into groups and compared with group-based trajectory modeling. Cognitive impairment and depressive symptoms associated with each group were identified by logistic regression. RESULTS: Three different pain trajectory groups were identified: drastic decline-minimum pain (47.7%), gentle decline-mild pain (45.5%), and slight decline-moderate pain (6.8%). Patients with cognitive impairment [odds ratio (OR) 11.01, 95% CI 2.99-10.51] and at risk for depression (OR 49.09, 95% CI 10.46-230.30) were more likely to be in the moderate pain group than the minimum pain group. Patients with cognitive impairment (OR 2.07, 95% CI 1.25-3.42) were more likely to be in the mild pain group than the minimum pain group. Patients at risk for depression (OR 9.68, 95% CI 3.16-29.63) were more likely to be in the moderate pain group than the mild pain group. CONCLUSIONS AND IMPLICATIONS: Identifying postoperative pain trajectories can provide insight into the most appropriate pain management for older persons following hip fracture surgery. Attention should focus on assessments for cognitive impairment and risk of depression to prevent persistent postoperative pain. Future studies of older patients with clinically diagnosed cognitive impairment and depression are suggested.

Atomic-level design of metalloenzyme-like active pockets in metal-organic frameworks for bioinspired catalysis.

Natural metalloenzymes with astonishing reaction activity and specificity underpin essential life transformations. Nevertheless, enzymes only operate under mild conditions to keep sophisticated structures active, limiting their potential applications. Artificial metalloenzymes that recapitulate the catalytic activity of enzymes can not only circumvent the enzymatic fragility but also bring versatile functions into practice. Among them, metal-organic frameworks (MOFs) featuring diverse and site-isolated metal sites and supramolecular structures have emerged as promising candidates for metalloenzymes to move toward unparalleled properties and behaviour of enzymes. In this review, we systematically summarize the significant advances in MOF-based metalloenzyme mimics with a special emphasis on active pocket engineering at the atomic level, including primary catalytic sites and secondary coordination spheres. Then, the deep understanding of catalytic mechanisms and their advanced applications are discussed. Finally, a perspective on this emerging frontier research is provided to advance bioinspired catalysis.

NiFe Nanoparticle Nest Supported on Graphene as Electrocatalyst for Highly Efficient Oxygen Evolution Reaction.

Designing cost-efffective electrocatalysts for the oxygen evolution reaction (OER) holds significant importance in the progression of clean energy generation and efficient energy storage technologies, such as water splitting and rechargeable metal-air batteries. In this work, an OER electrocatalyst is developed using Ni and Fe precursors in combination with different proportions of graphene oxide. The catalyst synthesis involved a rapid reduction process, facilitated by adding sodium borohydride, which successfully formed NiFe nanoparticle nests on graphene support (NiFe NNG). The incorporation of graphene support enhances the catalytic activity, electron transferability, and electrical conductivity of the NiFe-based catalyst. The NiFe NNG catalyst exhibits outstanding performance, characterized by a low overpotential of 292.3 mV and a Tafel slope of 48 mV dec-1, achieved at a current density of 10 mA cm- 2. Moreover, the catalyst exhibits remarkable stability over extended durations. The OER performance of NiFe NNG is on par with that of commercial IrO2 in alkaline media. Such superb OER catalytic performance can be attributed to the synergistic effect between the NiFe nanoparticle nests and graphene, which arises from their large surface area and outstanding intrinsic catalytic activity. The excellent electrochemical properties of NiFe NNG hold great promise for further applications in energy storage and conversion devices.

Photothermal-Switched Single-Atom Nanozyme Specificity for Pretreatment and Sensing.

Various applications lead to the requirement of nanozymes with either specific activity or multiple enzyme-like activities. To this end, intelligent nanozymes with freely switching specificity abilities hold great promise to adapt to complicated and changeable practical conditions. Herein, a nitrogen-doped carbon-supported copper single-atom nanozyme (named Cu SA/NC) with switchable specificity is reported. Atomically dispersed active sites endow Cu SA/NC with specific peroxidase-like activity at room temperature. Furthermore, the intrinsic photothermal conversion ability of Cu SA/NC enables the specificity switch by additional laser irradiation, where photothermal-induced temperature elevation triggers the expression of oxidase-like and catalase-like activity of Cu SA/NC. For further applications in practice, a pretreatment-and-sensing integration kit (PSIK) is constructed, where Cu SA/NC can successively achieve sample pretreatment and sensitive detection by switching from multi-activity mode to specific-activity mode. This study sets the foundation for nanozymes with switchable specificity and broadens the application scope in point-of-care testing.

The usability of an AAC pain description system for patients with acquired expressive communication disorders.

Augmentative and alternative communication (AAC) has been used by patients with acquired expressive communication disorders as an alternative to natural speech. The use of symbols to express pain, which is intangible, is challenging because designing a series of comprehensible symbols to represent personal experiences such as pain is not straightforward. This study describes (a) the development of symbols to express pain that were derived from Chinese pain-related similes and metaphors for an AAC mobile application developed specifically for this study known as PainDiary and (b) an assessment of the appropriateness of the app compared to conventional methods of collecting pain information. The symbols depicted headache pain and discomfort, which is prevalent among neurosurgical patients. The participants were 31 patients diagnosed with acquired expressive communication disorders who were receiving treatment in a neurosurgery general ward of Chang Gung Memorial Hospital in Taiwan and 14 nurses who worked on the ward. Pain information was collected by nurses using conventional methods and the PainDiary app. Assessment data, including the accuracy and efficiency of and user satisfaction with PainDiary, are compared. The results show that use of the app was effective in reporting pain and that patients required less time to report a pain event. The results further indicate that the PainDiary app was better received by younger individuals than by their older counterparts.

The relationships among perceived stress, resilience, sleep quality and first-month retention of newly employed nurses: A cross-sectional survey.

AIM: Newly employed nurses are subject to high workplace stress, which leads to a low retention rate. Resilience can reduce burnout among nurses. The aim of this study was to explore the relationships among perceived stress, resilience, sleep quality of new nurses during initial employment, and their impacts on first-month retention. DESIGN: This is a cross-sectional study design. METHODS: We used a convenience sampling method to recruit 171 new nurses between January and September 2021. The Perceived Stress Scale, Resilience Scale, and Pittsburgh Sleep Quality Inventory (PSQI) were conducted in the study. Logistic regression analysis was used to explore the impacts on first-month retention for newly employed nurses. RESULTS: The initial perceived stress, resilience, and sleep quality of the newly employed nurses were not correlated with the first-month retention rate. Forty-four per cent of the newly recruited nurses had sleep disorders. Resilience, sleep quality, and perceived stress of newly employed nurses were significantly correlated. Newly employed nurses assigned to their desired wards had lower perceived stress than their peers.

Two-Dimensional Fe-N-C Single-Atomic-Site Catalysts with Boosted Peroxidase-Like Activity for a Sensitive Immunoassay.

Single-atomic-site catalysts (SASCs) with peroxidase (POD)-like activities have been widely used in various sensing platforms, like the enzyme-linked immunosorbent assay (ELISA). Herein, a two-dimensional Fe-N-C-based SASC (2D Fe-SASC) is successfully synthesized with excellent POD-like activity (specific activity = 90.11 U/mg) and is used to design the ELISA for herbicide detection. The 2D structure of Fe-SASC enables the exposure of numerous single atomic active sites on the surface as well as boosts the POD-like activity, thereby enhancing the sensing performance. 2D Fe-SASC is assembled into competitive ELISA kit, which achieves an excellent detection performance for 2,4-dichlorophenoxyacetic acid (2,4-D). Fe-SASC has great potential in replacing high-cost natural enzymes and working on various advanced sensing platforms with high sensitivity for the detection of various target biomarkers.

Simultaneous detection of two herbicides in fruits and vegetables with nanoparticle-linked immunosorbent and lateral flow immunoassays.

Herbicides atrazine and acetochlor are used in crop production. Because of environmental and health hazards with respective maximum contamination levels of 3 and 20 ng/mL, quantifying these herbicides is important when considering presence in foods and vegetables. We utilized two Pd@Pt nanoparticle-amplified immunoassays, a colorimetric Pd@Pt nanoparticle-linked immunosorbent assay (NLISA) and differential pulse voltammetry (DPV) dependent on catalytic activity of Pd@Pt in a dual-lateral flow immunoassay (dual-LFIA-DPV). We achieved overall recoveries of 88.5-114 % in juice, fruit, and vegetable samples for both immunoassays. The NLISA yielded limits of detection (LODs) of 0.59 and 0.31 µg/kg and the dual-LFIA-DPV 0.27 and 0.51 µg/kg for the two respective species. Results for both immunoassays were validated by high-performance liquid chromatography (HPLC), for all food and drink samples though LODs are compromised when configuring the HPLC for both species with the same chromatogram. We expect Pd@Pt-based immunoassays to prove useful in various fields.

Trajectories of social support are associated with health outcomes and depressive symptoms among older Taiwanese adults with diabetes following hip-fracture surgery.

OBJECTIVE: This study examined trajectories of social support and their relationships with health outcomes over 2 years post hip-fracture surgery for older adults with diabetes mellitus (DM). METHODS: This was a secondary analysis of data derived from a clinical trial, which included 158 hip fractured older adults with DM who had completed the Medical Outcomes Study Social Support Survey at 1-, 12-, 18-, and 24-months following hospital discharge. Health outcomes for self-care, physical and nutritional status, mental health, and depression were assessed at 3-month intervals up to 24-months after hospital discharge. Trajectories of social support were derived with latent class analysis while hierarchical linear models were employed to assess the associations of social-support trajectory with health outcomes. RESULTS: Four social-support trajectories were derived for persons with DM following hip-fracture surgery: poor and declining (n = 18, 11.4%), moderate and stable (n = 29, 18.4%), high but declining (n = 34, 21.5%), and high and stable (n = 77, 48.7%). Relative to those in the poor and declining group, participants in the high and stable trajectory group performed better in Activities of Daily Living and quadriceps muscle power, had better mental Health-Related Quality of Life and nutritional status, and had fewer depressive symptoms. These differences persisted over the 2 years following hospital discharge. CONCLUSIONS: These results suggest social support for persons with DM should be continually assessed following hip-fracture surgery.

Supramolecular assemblies of a newly developed indole derivative for selective adsorption and photo-destruction of perfluoroalkyl substances.

Per-/polyfluoroalkyl substances (PFASs) contamination has caused worldwide health concerns, and increased demand for effective elimination strategies. Herein, we developed a new indole derivative decorated with a hexadecane chain and a tertiary amine center (named di-indole hexadecyl ammonium, DIHA), which can form stable nanospheres (100-200 nm) in water via supramolecular assembly. As the DIHA nanospheres can induce electrostatic, hydrophobic and van der Waals interactions (all are long-ranged) that operative cooperatively, in addition to the nano-sized particles with large surface area, the DIHA nanocomposite exhibited extremely fast adsorption rates (in seconds), high adsorption capacities (0.764-0.857 g g-1) and selective adsorption for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), outperformed the previous reported high-end PFASs adsorbents. Simultaneously, the DIHA nanospheres can produce hydrated electron (eaq-) when subjected to UV irradiation, with the virtue of constraining the photo-generated eaq- and the adsorbed PFOA/PFOS molecules entirely inside the nanocomposite. As such, the UV/DIHA system exhibits extremely high degradation/defluorination efficiency for PFOA/PFOS, even under ambient conditions, especially with the advantages of low chemical dosage requirement (µM level) and robust performance against environmental variables. Therefore, it is a new attempt of using supramolecular approach to construct an indole-based nanocomposite, which can elegantly combine adsorption and degradation functions. The novel DIHA nanoemulsion system would shed light on the treatment of PFAS-contaminated wastewater.

Engineering Atomic Single Metal-FeN4Cl Sites with Enhanced Oxygen-Reduction Activity for High-Performance Proton Exchange Membrane Fuel Cells.

Fe-N-C single-atomic metal site catalysts (SACs) have garnered tremendous interest in the oxygen reduction reaction (ORR) to substitute Pt-based catalysts in proton exchange membrane fuel cells. Nowadays, efforts have been devoted to modulating the electronic structure of metal single-atomic sites for enhancing the catalytic activities of Fe-N-C SACs, like doping heteroatoms to modulate the electronic structure of the Fe-Nx active center. However, most strategies use uncontrolled long-range interactions with heteroatoms on the Fe-Nx substrate, and thus the effect may not precisely control near-range coordinated interactions. Herein, the chlorine (Cl) is used to adjust the Fe-Nx active center via a near-range coordinated interaction. The synthesized FeN4Cl SAC likely contains the FeN4Cl active sites in the carbon matrix. The additional Fe-Cl coordination improves the instrinsic ORR activity compared with normal FeNx SAC, evidenced by density functional theory calculations, the measured ORR half-wave potential (E1/2, 0.818 V), and excellent membrane electrode assembly performance.

Single-Atomic Site Catalyst Enhanced Lateral Flow Immunoassay for Point-of-Care Detection of Herbicide.

Point-of-care (POC) detection of herbicides is of great importance due to their impact on the environment and potential risks to human health. Here, we design a single-atomic site catalyst (SASC) with excellent peroxidase-like (POD-like) catalytic activity, which enhances the detection performance of corresponding lateral flow immunoassay (LFIA). The iron single-atomic site catalyst (Fe-SASC) is synthesized from hemin-doped ZIF-8, creating active sites that mimic the Fe active center coordination environment of natural enzyme and their functions. Due to its atomically dispersed iron active sites that result in maximum utilization of active metal atoms, the Fe-SASC exhibits superior POD-like activity, which has great potential to replace its natural counterparts. Also, the catalytic mechanism of Fe-SASC is systematically investigated. Utilizing its outstanding catalytic activity, the Fe-SASC is used as label to construct LFIA (Fe-SASC-LFIA) for herbicide detection. The 2,4-dichlorophenoxyacetic acid (2,4-D) is selected as a target here, since it is a commonly used herbicide as well as a biomarker for herbicide exposure evaluation. A linear detection range of 1-250 ng/mL with a low limit of detection (LOD) of 0.82 ng/mL has been achieved. Meanwhile, excellent specificity and selectivity towards 2,4-D have been obtained. The outstanding detection performance of the Fe-SASC-LFIA has also been demonstrated in the detection of human urine samples, indicating the practicability of this POC detection platform for analyzing the 2,4-D exposure level of a person. We believe this proposed Fe-SASC-LFIA has potential as a portable, rapid, and high-sensitive POC detection strategy for pesticide exposure evaluation.

Combined Effects of Cognitive Impairment and Nutritional Trajectories on Functional Recovery for Older Patients after Hip-Fracture Surgery.

OBJECTIVES: Malnutrition and cognitive impairment are associated with poor functional recovery in older adults following hip-fracture surgery. This study examined the combined effects of cognitive impairment and nutritional trajectories on postoperative functional recovery for older adults following hip-fracture surgery. DESIGN: Prospective longitudinal correlational study. SETTING AND PARTICIPANTS: This study recruited 350 older adults (≥60 years of age) who received hip-fracture surgery at a 3000-bed medical center in northern Taiwan from September 2012 to March 2020. METHODS: Participant data were collected over a 2-year period after surgery for nutritional and cognitive status and activities of daily living (ADLs). Participants were grouped by type of nutritional trajectory using group-based trajectory modeling. Generalized estimating equations analyzed associations between trajectory groups/cognitive status at discharge and performance of ADLs. RESULTS: Nutritional trajectories best fit a 3-group trajectory model: malnourished (19%), at-risk of malnutrition (40%), and well-nourished (41%). Nutritional status for the malnourished group declined from 12 months to 24 months following surgery; nutritional status remained stable for at-risk of malnutrition and well-nourished groups. Interactions for cognitive impairment-by-nutritional status were significant: the malnourished + intact cognition subgroup had significantly better ADLs than the malnourished + cognitive impairment subgroup (b = 27.1, 95% confidence interval = 14.0-40.2; P < .001). For at-risk of malnutrition and well-nourished groups, there were no significant differences between cognitive impairment and intact cognition in ADLs. These findings suggest that nutritional status may buffer the negative effect of cognitive impairment on ADLs. CONCLUSIONS AND IMPLICATIONS: Better nutritional status over time for older adults following hip fracture can protect against adverse influences of cognitive impairment on ADLs during postoperative recovery. Participants with malnutrition and cognitive impairment had the poorest ADLs. These findings suggest interventions tailored to improving nutritional status may improve recovery for older adults following hip-fracture surgery.

Single-Atomic Iron Doped Carbon Dots with Both Photoluminescence and Oxidase-Like Activity.

Multifunctional nanozymes can benefit biochemical analysis via expanding sensing modes and enhancing analytical performance, but designing multifunctional nanozymes to realize the desired sensing of targets is challenging. In this work, single-atomic iron doped carbon dots (SA Fe-CDs) are designed and synthesized via a facile in situ pyrolysis process. The small-sized CDs not only maintain their tunable fluorescence, but also serve as a support for loading dispersed active sites. Monoatomic Fe offers SA Fe-CDs exceptional oxidase-mimetic activity to catalyze 3,3',5,5'-tetramethylbenzidine (TMB) oxidation with fast response (Vmax  = 10.4 nM s-1 ) and strong affinity (Km  = 168 µM). Meanwhile, their photoluminescence is quenched by the oxidation product of TMB due to inner filter effect. Phosphate ions (Pi) can suppress the oxidase-mimicking activity and restore the photoluminescence of SA Fe-CDs by interacting with Fe active sites. Based on this principle, a dual-mode colorimetric and fluorescence assay of Pi with high sensitivity, selectivity, and rapid response is established. This work paves a path to develop multifunctional enzyme-like catalysts, and offers a simple but efficient dual-mode method for phosphate monitoring, which will inspire the exploration of multi-mode sensing strategies based on nanozyme catalysis.