Yuxiu Xiao

The ultrasensitive detection of epigenetic DNA modifications typically relies on enzyme-dependent amplification, which is often hindered by structural bias and matrix interference. Herein, we report a programmable, amplification-free ratiometric sensing platform driven by in situ growth of dual-emissive lanthanide metal−organic frameworks (Ce/Eu-MOFs) directly onto nucleic acid templates. Mechanistic investigations, integrating 31P NMR spectroscopy and density functional theory (DFT) calculations, reveal that the DNA phosphate backbone acts as the thermodynamically favored nucleation site, governing the regioselective assembly of the Ce/Eu-MOFs. Furthermore, the integration of computational and experimental approaches established a rational screening principle to identify dipicolinic acid as the optimal MOF ligand. By coupling this in situ MOF growth with selective chemical labeling and magnetic enrichment, the designed scaffold enables highly specific recognition and self-calibrating ratiometric quantification of 5-formylcytosine (5fC), a critical epigenetic biomarker. This platform achieves exceptional amplification-free sensitivity with a limit of detection of 0.001%, demonstrating strong quantitative agreement with the clinical gold-standard ELISA-based analysis. Finally, the proposed method was successfully applied to profile dynamic 5fC variations across complex tissue samples. This work establishes a biomolecule-directed Ln-MOF growth strategy for precise epigenetic analysis, providing a versatile and robust framework for developing advanced, amplification-free analytical tools.

The pronounced lipophilicity and inherent stability of the C–Cl bond in organochlorine pesticides (OCPs) pose significant challenges to their simultaneous degradation and visual detection. Herein, we have developed a visual colorimetric platform for OCP degradation and detection using nano ZnTPyP. Theoretical calculations and experimental results reveal that the nature of the substituent plays a critical role in modulating the catalytic activity of Zn-based porphyrins, with the strongly electron-withdrawing pyridyl group notably enhancing their oxidase-like activity. Subsequently, pyridine-substituted zinc porphyrins effectively catalyze the generation of reactive oxygen species (ROS) from O2, thereby attacking the C–Cl bonds in OCPs and leading to their degradation. To prevent self-aggregation and improve analytical performance, we developed a solvent-effect-enabled exfoliation-convolution strategy to fabricate ZnTPyP hollow nanotubes: the stacked porphyrins exfoliate in aqueous solution and self-convolute under surface tension into hollow nanotubes. Upon nano ZnTPyP-mediated degradation of OCPs, the released H+ ions are captured by bromothymol green (BG), triggering a distinct green-to-yellow color change. Based on this principle, a rotatable colorimetric device enables rapid on-site semiquantitative analysis with a detection limit of 0.01 μg/mL. Linear discriminant analysis achieves 100% accurate differentiation among five structurally similar OCPs. Finally, the applicability of this device was validated in four different real samples, such as cabbage, lily, chrysanthemum, and lake water, with recoveries ranging from 90.20% to 109.40%. This work not only provides mechanistic insights into porphyrin-based nanozymes for pollutant degradation but also establishes an integrated platform for simultaneous OCP degradation and on-site visual detection.

Rapid, ultrasensitive detection of cardiac troponin I (cTnI) is critical for the early diagnosis of acute myocardial infarction (AMI). However, CRISPR-Cas systems, despite their unparalleled nucleic acid detection performance, face inherent bottlenecks in protein sensing, including inefficient signal transduction, high background noise, and insufficient anti-interference capability in complex biological matrices. Herein, we report a modular fluorescence signal transduction platform integrating aptamer-functionalized magnetic beads, lanthanide metal–organic frameworks (Ln-MOFs) with high nucleic acid affinity, and CRISPR-Cas12a–mediated collateral cleavage amplification for sensitive cTnI detection. Target cTnI binding to magnetic bead-immobilized aptamers drives the formation of sandwich complexes with CRISPR activator DNA (act)–functionalized Ln-MOFs, triggering phosphate-mediated release of act. The liberated act initiates robust Cas12a trans-cleavage activity, generating an amplified fluorescence readout. This platform achieves a limit of detection (LOD) of 0.1 pg mL–1 in serum samples, with excellent specificity against off-target interfering proteins. Validation in 28 clinical serum samples demonstrates near-perfect agreement with standard clinical ELISA measurements and yields an area under the curve (AUC) of 0.995, confirming its clinical diagnostic accuracy. Furthermore, the modular design enables facile reconfiguration for diverse protein biomarkers via aptamer substitution, providing a universal strategy to expand CRISPR-Cas systems toward non-nucleic acid target detection.

Despite notable advances in molecular diagnostics, developing ultrasensitive biosensors for biomarker quantification remains a critical unmet need. Herein, we address this gap by engineering lanthanide metal–organic frameworks (Ln-MOFs) as artificial receptor aptamers (ARAs) via rational ligand design and guided optimization. Our lead Eu–TPTC Ln-MOF ([1,1′:4′,1″]-terphenyl-3,3″,5,5″-tetracarboxylic acid), optimized for maximal surface negativity, binds the cationic biomarker (cardiac troponin I, cTnI) with highly efficient electrostatic affinity. This strong affinity couples synergistically with specific target recognition to enable robust, binding-triggered signal transduction. A phosphate-mediated cascaded amplification strategy achieves a 7250-fold fluorescence enhancement and a cTnI limit of detection (LOD) of 1 pg mL^–1. This performance meets clinical requirements for early diagnosis and significantly outperforms conventional ELISA in sensitivity (12.3-fold), speed, and cost-effectiveness. We establish three core ARA design principles: (i) a rigorous experimental structure–property framework linking ligand functional groups to MOF surface zeta potentials; (ii) multiscale interface engineering combining molecular docking and fluorescence assays; and (iii) an affinity-driven signal-leverage strategy. This label-free platform enables miniaturized, field-deployable diagnostics, critical for resource-limited settings. Notably, it provides a general framework for MOF-based ARAs, extends to diverse biomarkers, and lays a solid foundation for the development of highly responsive, enzyme-free biosensors for ultrasensitive biomarker quantification.

Enzyme cascade-based bioinspired array hold promise for high-resolution recognition of structurally similar compounds; however, most enzymes lack a direct substrate-to-product relationship, necessitating stable and editable artificial messengers for their integration. Herein, the exposed crystal surfaces of ligand-free manganese dioxide (MnO₂) are found to facilitate efficient single-stranded DNA (ssDNA) adsorption and separation. Theory-guided crystal phase modulation further reveals that β-MnO₂ can capture the phosphate backbone of ssDNA through a surface potential-induced oxygen-vacancy-filling mechanism. Leveraging nuclease’s bioactivity, β-MnO₂-ssDNA are engineered on demand as artificial messengers to cascade hydrolases and nucleases via reductive product-mediated self-sacrifice and release of Mn²⁺ and ssDNA. Notably, nucleases can capture organophosphorus (OPs) from phosphorylated hydrolases before their complete aging. Such protein competition among hydrolase-OP-nuclease triggers accumulative differentiation across pathways, improving the resolution for structurally similar OPs. Accordingly, we proposed a gustatory-inspired pathway-signaling-recognition system (GPS), where the GPS-based array delivers differential optical signals via multipathway responses and generates unique digital encoding for precisely discriminating 19 structurally similar OPs. With chlorpyrifos as a representative target, the GPS-based array provides high-resolution qualitative/quantitative assays and supports dynamic degradation monitoring in multidimensional samples. These findings provide inorganic insights into the MnO₂-ssDNA interaction mechanism and establish the GPS-based array as a generalizable paradigm for high-resolution biosensing.

Nuclease nanozymes promise robust, tailorable alternatives to natural nucleases, but suffer from their limited hydrolytic activity due to the Lewis acidity‐centric mechanistic dogma and the unclear role of nanozyme–DNA interactions. Here, we report an affinity‐driven strategy that upends conventional cognition. A series of lanthanide metal‐organic frameworks (Ln‐MOFs) were constructed, with catalytic efficiency decoupled from simple acid strength. Activity increased with the lanthanide atomic number despite a decrease in nanozyme‐DNA affinity. Among these, Yb‐BDC (terephthalic acid‐based) exhibited the highest DNA‐cleaving efficiency reported to date (half‐life ≈ 30 min), yet showed minimal activity toward the traditional model substrate bis(4‐nitrophenyl) phosphate (BNPP), thereby challenging the conventional Lewis acidity‐driven paradigm. This unexpected inverse relationship reveals a critical binding‐release cycle as the true driver of DNA hydrolysis. Capitalizing on this discovery, we developed a synthetic CRISPR/Cas‐inspired biosensing platform by integrating Yb‐BDC with rolling circle amplification, replacing natural nucleases. This system enables ultrasensitive detection of non‐nucleic acid targets, expanding the scope of nanozymes in diagnostic applications. Our findings not only establish host–guest interaction engineering as a new paradigm for nuclease nanozymes design but also pioneer a modular framework for their application in biosensing technologies.

Perovskites nanoparticles (PNPs), promising materials in fluorescence biosensing, have has their practical applications stymied by poor stability in polar solvents. Integrating PNPs into metal–organic frameworks (MOFs) offers a solution by enhancing their compatibility with various environments. Lanthanide MOFs (Ln‐MOFs) are particularly advantageous due to their customizable structure, enhanced stability, and intrinsic fluorescence. Herein, the mechanism by which hybrid materials achieve a balance between physical and fluorescence properties is elucidated. Through theoretical calculations, 2,2'‐bipyridine‐5,5'‐dicarboxylic acid is selected as the ligand to sensitize Eu ³⁺ and facilitate Pb ²⁺ chemisorption. In addition, 4‐bromobutyric acid is not only employed to create hierarchical Eu‐MOFs and optimize the framework for in situ growth of polycrystalline perovskites but also utilized to generate zwitterionic ligands through an S _N 2 reaction with MOF cages restricted n‐octylamine, ensuring the stable dispersion of hybrid materials in ethyl acetate (polar solvent). The prepared PNPs@Ln‐MOF exhibits significantly enhanced fluorescence lifetime (50‐fold) and stability in polar solvents. Besides, the highly sensitive fluorescence color shift of PNPs@Ln‐MOF in response to ammonia offers a generalizable strategy for ammonia‐mediated biosensing device. Supported by CRISPR/Cas technology, this device allows for precise on‐site nucleic acid assay (LOD = 200 fM), pioneering advanced applications of perovskite‐based hybrid materials in biosensing.

CsPbX₃ perovskites are emerging photocatalysts with promising biosensing applications, yet designing highly active ultraviolet photocatalysts and clarifying their photocatalytic mechanism in the aqueous phase remain challenging. This study reveals the oxidase-like activity of hydrophilic CsPbX₃ nanoparticles (NPs) under ultraviolet light (UV-OXD-like activity), wherein soluble oxygen is catalyzed into singlet oxygen (¹O₂), leading to rapid oxidation of the chromogenic substrate within seconds. Halogen atoms and doped metal ions can significantly influence the band structure of the CsPbX₃ NPs. Among these, Cl atoms endow a wide bandgap (∼3.0 eV) favorable for UV absorption of CsPbX₃ NPs, while the deep trap states introduced by Bi³⁺ promote nonradiative recombination, thus enabling Bi³⁺:CsPbCl₃ NPs to have excellent UV-OXD-like activity. Notably, ascorbic acid (AA) formed by alkaline phosphatase (ALP)-catalyzed hydrolysis of the substrate can passivate deep trap states through hydrogen bonding. The presence of the target nucleic acid activates the trans-cleavage activity of LbCas12a, releasing ALP from magnetic beads. Accordingly, an enzyme cascade reaction coupled with a UV-controlled readout is proposed for the BRAF V600E assay with a low limit of detection (0.10 pM, preamplification-free) and applied to human thyroid cancer tissue samples. This work provides a perspective for the design and bioapplication of hydrophilic perovskite-based UV photocatalysts.

Aberrant epigenetic modifications (EMs) serve as critical biomarkers but remain challenging to detect due to their low abundance in biological samples. A lanthanide metal–organic framework (Ln‐MOF) bio‐barcode method integrating the dual actions of ultrahigh DNA loading density and anion–π interaction‐driven fluorescence enhancement for the ultrasensitive detection of EMs, such as 5‐formylcytosine (5fC), is developed. The system employs streptavidin‐functionalized magnetic beads to selectively capture biotinylated 5fC‐modified nucleic acids, which then capture Er–organic framework probes (UiO‐66 (Er)) tagged with thousands of quenched fluorescent oligonucleotides (FAM‐ODN). After magnetic separation, phosphate‐induced desorption restores the fluorescence of oligonucleotides, signaling the presence of 5fC. Subsequently, free phosphate, functioning as both a strong base and an anion, further amplifies fluorescence by altering the conformation of FAM molecules. This dual‐action mechanism combines high nucleic acid loading capacity of Ln‐MOF and conformation‐regulated fluorescence enhancement enables the fluorescent bio‐barcode to achieve a detection limit of 0.0225% content. The detection results of 5fC in cellular and thyroid cancer tissue samples confirm global 5fC downregulation as a robust epigenetic hallmark of cancer. The enzyme‐ and amplification‐free design ensures robustness and cost‐efficiency, while modular probe architecture enables adaptation to diverse low‐abundance targets, from epigenetic modifications to protein biomarkers.