A dual-ratio fluorescent probe with a single excitation triple-signal to synchronously detect PTK7 and miRNA-21 for breast cancer early diagnosis

Signal-on electrochemiluminescence resonance energy transfer biosensor for miRNA-543 based on CRISPR/Cas13a and magnetic separation

In this study, an electrochemiluminescence resonance energy transfer (ECL-RET) biosensor with high sensitivity and strong resistance to interference was constructed based on the CRISPR/Cas13a system and magnetic separation for ovarian cancer biomarker miR-543 detection. Mesoporous silica nanoparticles embedded with Ru(bpy)32+ (Ru@SiO2) have high electrochemiluminescence (ECL) response was chosen as energy donor. Single-stranded DNA S1 containing "rUrU" motif was immobilized on AuNRs (AuNRs-S1), which hybridized with single-stranded DNA S2 modified SAMBs (SAMBs-S2) to form AuNRs-S1/S2-SAMBs complex, this has been used as energy acceptor. In the absence of the target, Cas13a remained inactive, preventing the cleavage of S1, thereby maintaining the association of AuNRs with SAMBs. Then they were added in Ru@SiO2 solution after magnetic separation. The electrostatic adsorption between the negatively charged AuNRs and the positively charged Ru@SiO2 cause the occurrence of ECL-RET and low ECL signal had been detected. When the target was added, Cas13a was activated and resulted in the non-specifically cleaving of S1, so AuNRs detached from SAMBs. After magnetic separation, fewer AuNRs participated in ECL-RET, leading to an enhanced ECL signal detected. The change in ECL intensity (ΔECL) exhibited a linear correlation with the logarithm of miR-543 concentration within the range of 10 fM to 10 nM, with a detection limit of 6.91 fM. The biosensor had been applied to detect miR-543 in clinical samples with high accuracy.

Bifunctional Fe-CDs@MOF composite nanozyme based ratiometric fluorescent probe for the detection of xanthine in fish

A novel bifunctional Fe-CDs@MOF composite nanozyme was synthesized successfully by loading Fe doped carbon dots (Fe-CDs) onto metal-organic framework (MOF) MIL-101 (Fe). The introduction of Fe-CDs enhanced the peroxidase (POD)-like activity of MOF and endowed it with excellent fluorescence properties. Considering the dual functions of Fe-CDs@MOF, we combined it with o-phenylenediamine (OPD)/xanthine oxidase (XOD) to construct a ratiomeric fluorescence probe for xanthine (XAN) detection. XAN was first oxidized by XOD to produce H2O2, then Fe-CDs@MOF exerted its POD-like activity to catalyze the reaction between OPD and H2O2 to form 2,3-diaminophenazine (DAP). DAP in turn quenched the fluorescence of Fe-CDs@MOF as a result of internal filtration effect. The ratio of the fluorescence intensity of DAP and the fluorescence intensity of Fe-CDs@MOF indicated the XAN content. The XAN detection range was 1-100 μM with a limit of detection of 0.36 μM. The ratiometric fluorescence probe was utilized to analyze XAN in fish samples, and the results obtained were in good agreement with those assayed by high performance liquid chromatography. The method also had the ability to test the freshness of frozen fish. This study provides a novel approach for the design and application of Fe-CDs@MOF composite nanozyme.

Exponential rolling circle amplification-hybridization chain reaction (EXRCA-HCR) for AgNPs@gel-enhanced fluorescence ultrasensitive detection of miRNA-21

MicroRNA (miRNA) is a common tumor marker, whose abnormal expression is often closely related to the occurrence of various diseases. However, the conventional method for detecting miRNA is qRT-PCR, requiring additional reverse transcription steps, well-trained professionals, and expensive thermal cycling equipment. In this work, we propose a novel isothermal amplification technique (exponential rolling circle amplification-hybridization chain reaction, EXRCA-HCR) for AgNPs@gel-enhanced fluorescence specific and ultrasensitive detection of miRNA-21. This novel technique consists of rolling circle amplification (RCA), exponential isothermal amplification reaction (EXPAR) and hybridization chain reaction (HCR). Combining these three amplification methods, EXRCA-HCR provides a unique cascade amplification strategy, inheriting the advantages of linear amplification and exponential amplification. Under optimal conditions, this novel EXRCA-HCR exhibits a wide fluorescent detection range from 200 fM to 200 nM for miRNA-21, with low detection limit of 21.47 fM. By introducing AgNPs@gel, the fabricated paper-based fluorosensor based on EXRCA-HCR provides a simple and rapid visual detection of miRNA-21. This research puts forward a promising approach for detecting miRNA-21, which can be applied for early diagnosis.

CRISPR-Cas12a/Cas13a Multiplex Bioassay for ctDNA and miRNA by Mass Spectrometry

The CRISPR-Cas system, particularly CRISPR-Cas12a and CRISPR-Cas13a, has been widely utilized in constructing various biosensors due to their "trans-cleavage" ability as a means of signal amplification. However, this universal "trans-cleavage" characteristic also presents a challenge for realizing CRISPR-Cas multiplexed bioanalysis. Besides, potential signal cascading interference and complicated design are notable obstacles in CRISPR-Cas multiplexed bioanalysis. Herein, we propose a mass spectrometry method that leverages the CRISPR-Cas12a/13a system to achieve simultaneous detection of ctDNA and miRNA. Based on the properties of the CRISPR-Cas12a/13a system, two types of nanoparticle reporter probes have been engineered, using cancer-related biomarkers ctDNA and miR-21 as our model analytes. The nanoparticle tags, which intrinsically incorporated millions of detectable atoms, combined with the CRISPR-Cas12a/Cas13a system's "trans-cleavage" ability, allow the proposed mass spectrometry strategy to achieve fmol-level detection limits without any nucleic acid amplification procedures. The assay was successfully applied to human serum samples, demonstrating its potential for early disease diagnosis and progression tracking.

Urease-Driven Janus Nanomotors for Dynamic Enrichment and Multiplexed Detection of Bladder Cancer MicroRNAs in Urine

Bladder cancer diagnosis typically involves approaches such as cystoscopy, biopsy, urine cytology, and medical imaging. However, these invasive procedures carry a risk of complications, and direct in vitro detection on clinical samples often results in low sensitivity. Therefore, this study proposed urease-driven magnetic nanomotors for the simultaneous detection of bladder cancer biomarkers miRNA-21 and miRNA-182 in urine samples, aiming for noninvasive diagnosis. The nanomotor was constructed from gold nanorods, mesoporous organo-silica, Fe3O4, and hairpin DNA (hDNA), functioning as a recognition probe for the target miRNAs. In the urea solution, urease catalyzed urea into ammonia and carbon dioxide, propelling the nanomotor for about 60 min, which enhanced the capacity of the probes to capture the target miRNAs. Subsequently, magnetic enrichment enabled highly sensitive dual-miRNA analysis, allowing quantification of miRNA-21 and miRNA-182 with detection limits of 29 and 362 fM, respectively. The nanoprobes also effectively detected miRNAs in spiked urine samples. This simultaneous detection of multiple miRNAs increased the reliability of cancer diagnosis, presenting a novel noninvasive strategy for bladder cancer detection through precise in vitro analysis of actual urine samples.

Anti-PTK7 Monoclonal Antibodies Suppresses Oncogenic Phenotypes in Cellular and Xenograft Models of Triple-Negative Breast Cancer

Protein tyrosine kinase 7 (PTK7), a catalytically defective receptor protein tyrosine kinase, is frequently upregulated in various cancers, including triple-negative breast cancer (TNBC), and is associated with poor clinical outcomes. Analysis of The Cancer Genome Atlas (TCGA) data confirmed that PTK7 mRNA expression is significantly higher in TNBC tumor tissues compared with adjacent normal tissues and non-TNBC breast cancer subtypes. Kaplan-Meier survival analysis demonstrated a strong correlation between high PTK7 expression and worse relapse-free survival in TNBC patients (HR = 1.46, p = 0.015). In vitro, anti-PTK7 monoclonal antibodies (mAbs) significantly reduced proliferation, wound healing, migration, and invasion in TNBC MDA-MB-231 cells. Ki-67 immunofluorescence assays revealed substantial decreases in cell proliferation following treatment with PTK7 mAbs (32-m, 43-m, 50-m, and 52-m). Moreover, actin polymerization, a critical process in cell migration and invasion, was markedly impaired upon PTK7 mAb treatment. In vivo, PTK7 mAbs significantly reduced tumor volume and weight in a TNBC xenograft mouse model compared with controls. Treated tumors exhibited decreased expression of Ki-67 and vimentin, indicating reduced proliferation and epithelial-to-mesenchymal transition. These findings highlight PTK7 as a promising therapeutic target in TNBC and demonstrate the potent anti-cancer effects of PTK7-neutralizing mAbs both in vitro and in vivo. Further exploration of PTK7-targeted therapies, including humanized mAbs and antibody-drug conjugates, is warranted to advance treatment strategies for PTK7-positive TNBC.

Visual aptasensor based on PtNPs/g-C3N4 and DNase I for the field detection of acetamiprid

A visual aptasensor based on the combination of graphitic carbon nitride loaded with platinum nanoparticles (PtNPs/g-C3N4) and deoxyribonuclease I (DNase I) was developed for detecting acetamiprid. The prepared PtNPs/g-C3N4 exhibited excellent peroxidase (POD)-like activity, demonstrating the capacity to oxidize the colourless o-phenylenediamine (OPD) to produce the coloured product diaminophenazine (DAP) in the presence of hydrogen peroxide (H2O2). The DNA aptamer of acetamiprid can adsorb onto the surface of PtNPs/g-C3N4, thereby inhibiting its POD activity. The binding of acetamiprid to its aptamer results in the aptamer desorbing from the surface of PtNPs/g-C3N4 and subsequent digestion by DNase I. Ascribed to the synergistic effect of these factors, the aptasensor can achieve the rapid on-site detection of acetamiprid based on the acetamiprid-induced the colour change of the solution just with the smartphone. Furthermore, due to the remarkable fluorescence signal of DAP at 570 nm, the aptasensor under fluorescence mode enables highly sensitive and quantitative detection of acetamiprid with a linear range of 1 ng/mL to 4 µg/mL and a detection limit as low as 0.31 ng/mL. The aptasensor has successfully realized the detection of acetamiprid in river water and cucumber samples, offering a novel perspective for the rapid assessment of environmental pollution and food safety risks associated with acetamiprid residues.

Identification of cell-free circulating epigenomic biomarkers for early diagnosis and response to therapies in breast cancer patients

The increasing prevalence of breast cancer presents a significant global health challenge, highlighting the urgent need for improved diagnostic and treatment monitoring methods. The non-invasive nature of cell-free circulating epigenomic biomarkers, such as methylated DNA (metDNA) and microRNAs (miRNAs), offers a reassuring approach to identifying breast cancer patients in the early stages and assessing their response to therapy. This approach holds great promise for diagnosis and treatment evaluation, prioritizing patient comfort and well-being. Cell-free circulating metDNA and miRNAs are released into the bloodstream from dying tumor cells through apoptosis and necrosis, carrying tumor-specific genetic and epigenetic changes. These changes encompass alterations in DNA methylation patterns, are pivotal in regulating gene expression, and are frequently disrupted in cancer. The interplay between these processes and the dynamic release of epigenomic biomarkers provides a real-time snapshot of the genetic and epigenetic features of the tumor. Integrating the analysis of metDNA and miRNA biomarkers into clinical practice can facilitate the early detection of breast cancer and improve the precision of treatment monitoring. By tracking changes in these biological markers, healthcare professionals can make informed decisions regarding modifications to therapy, ultimately enhancing patient outcomes. Gaining insights into the underlying mechanisms of cell-free circulating epigenomic biomarkers offers a groundbreaking approach to diagnosing and treating breast cancer.

T7 RNA polymerase-mediated rolling circle transcription and the CRISPR-Cas13a cascade reaction for sensitive and specific detection of piRNA

The aberrant expression of piRNAs in germ cells is a potential cause of male infertility. Establishing diagnostic methods with highly specific biomarkers for male infertility is important for accurate diagnosis and treatment of male infertility. In this study, we proposed a novel method combining rolling circle transcription (RCT) and Cas13a techniques, which utilized the high amplification efficiency of RCT and the two different RNase activities possessed by Cas13a, establishing a highly sensitive and specific assay for male infertility-associated piRNA. First, a circular DNA template was synthesized by hybridizing linear ssDNA with the T7 promoter. The nick in the circular DNA was closed by T4 DNA ligase. In the presence of T7 RNA polymerase, the closed circular DNA produced tandemly repeated pre-crRNA. The RNase activity of Cas13a was used to process pre-crRNAs to form mature crRNA. Guided by crRNA, Cas13a specifically recognized piRNA and activated collateral activity. Activated Cas13a disaggregated thousands of fluorescent probes for each target RNA detected, resulting in powerful signal amplification. As a proof of concept, piR-hsa-14 was used as the validation target. The limit of detection was as low as 3.32 fM with a good linearity in the range of 100 fM to 50 pM. Recovery of piR-hsa-14 ranged from 91.33% to 112.63% in spiked recovery experiments using human serum samples. The results revealed that this method has the advantages of high sensitivity, sufficient accuracy and good reproducibility. We believe that this method could have a promising future as a potential tool for clinical diagnosis of male infertility.

Simultaneous detection of breast cancer biomarkers HER2 and miRNA-21 based on duplex-specific nuclease signal amplification

The detection of a single biomarker is prone to false negative or false positive results. Simultaneous analysis of two biomarkers can greatly improve the accuracy of diagnosis. In this work, we designed a new method for coinstantaneous detection of two breast cancer biomarkers miRNA-21 and HER2 using the properties of duplex-specific nuclease (DSN). Cy5-labeled DNA1 and FAM-labeled DNA2 are used as signal probes to distinguish the two signals. When the sample contains the targets HER2 and miRNA-21, HER2 binds to the HER2 aptamer on the double-stranded DNA2, while miRNA-21 binds to the complementary DNA1. Then, DSN enzyme is added to cut the DNA probes adsorbed on the HER2 aptamer and miRNA-21, releasing the fluorescent groups, which can be readsorbed to the empty sites, thus repeating the cutting of the probes and producing an exponential signal amplification with two distinct fluorescent signals. The detection limits of miRNA-21 and HER2 are 1.12 pM and 0.36 ng mL-1, respectively, with linear ranges of 5 pM to 50 pM and 1 ng mL-1 to 15 ng mL-1. The method was validated in real biological samples, providing a new approach for synchronous analysis of important markers in breast cancer.

A Triple Signal Amplification Strategy for Accurate and Ultrasensitive miRNA-21 Detection

A triple signal amplification strategy was integrated with a built-in double electrode and external energy storage device to fabricate a novel self-powered biosensor for ultrasensitive detection of miRNA-21. Specifically, DNA tetrahedra and haripin2-glucose oxidase are modified on the surface of the biocathode and bioanode by catalytic hairpin assembly (CHA) to achieve dual signal amplification. Moreover, triple signal amplification is realized by including an external capacitor. Consequently, the as-constructed self-powered biosensor demonstrates a low detection limit of 0.06 fM toward the miRNA-21 assay within the range of 0.1 fM to 10 pM. This study presents a practical and sensitive approach to timely cancer detection.

Simultaneous Detection of Micro-RNAs by a Disposable Biosensor via the Click Chemistry Connection Strategy

Simultaneous detection of multiple breast cancer-associated miRNAs significantly raises the accuracy and reliability of early diagnosis. In this work, disposable carbon fiber paper serves as the biosensing interface, linking DNA probes via click chemistry to efficiently capture targets and signals efficiently. DNA probes have multiple recognition domains that trigger a cascade reaction through the helper probes and targets, resulting in two signals output. The signals are centrally encapsulated in the pore of the MIL-88(Fe)-NH2. The signal carriers are directed by signal probes to the recognition domains that correspond to the DNA probes. The biosensor is selective and stable, and it can quantify miRNA-21 and miRNA-155 simultaneously with detection limits of 0.64 and 0.54 fmol/L, respectively. Furthermore, it demonstrates satisfactory performance in tests conducted with normal human serum and cell lysate. Overall, this method makes a satisfactory exploration to realize an inexpensive and sensitive biosensor for multiple biomarkers.

A double-emission molecularly imprinted ratiometric fluorescent sensor based on carbon quantum dots and fluorescein isothiocyanate for visual detection of p-nitroaniline

A novel molecularly imprinted ratiometric fluorescent sensor CQDs@MIP/FITC@SiO2 for the detection of p-nitroaniline (p-NA) was constructed through the mixture of CQDs@MIP and FITC@SiO2 in the ratio of 1:1 (VCQDs@MIP:VFITC@SiO₂). The polymers of CQDs@MIP and FITC@SiO2 were prepared by sol-gel method and reversed-phase microemulsion method, respectively. CQDs@MIP was used as the auxiliary response signal and FITC@SiO2 was used as the reference enhancement signal. The signal was measured at excitation/emission wavelengths of 365/438, 512 nm. The sensor showed good linearity in the concentration range 0.14-40.00 µM (R2 = 0.998) with a detection limit of 0.042 µM for p-NA. The color change of "blue-cyan-green" could be observed by the naked eye under 365 nm UV light, thus realizing the visual detection of p-NA. The sensor presented comparable results compared with high-performance liquid chromatography (HPLC) method for the detection of p-NA in hair dye paste and aqueous samples with recoveries of 96.8-103.7% and 95.8-104.4%, respectively. It was demonstrated that the constructed sensor possesses the advantages of simplicity, excellent selectivity, superior sensitivity, and outstanding stability.

FRET Luminescent Probe for the Ratiometric Imaging of Peroxynitrite in Rat Brain Models of Epilepsy-Based on Organic Dye-Conjugated Iridium(III) Complex

Epilepsy is a chronic neurological disorder characterized by recurrent seizures globally, imposing a substantial burden on patients and their families. The pathological role of peroxynitrite (ONOO-), which can trigger oxidative stress, inflammation, and neuronal hyperexcitability, is critical in epilepsy. However, the development of reliable, in situ, and real-time optical imaging tools to detect ONOO- in the brain encounters some challenges related to the depth of tissue penetration, background interference, optical bleaching, and spectral overlapping. To address these limitations, we present Ir-CBM, a new one-photon and two-photon excitable and long-lived ratiometric luminescent probe designed specifically for precise detection of ONOO- in epilepsy-based on the Förster resonance energy transfer mechanism by combining an iridium(III) complex with an organic fluorophore. Ir-CBM possesses the advantages of rapid response, one-/two-photon excitation, and ratiometric luminescent imaging for monitoring the cellular levels of ONOO- and evaluating the effects of different therapeutic drugs on ONOO- in the brain of an epilepsy model rat. The development and utilization of Ir-CBM offer valuable insights into the design of ratiometric luminescent probes. Furthermore, Ir-CBM serves as a rapid imaging and screening tool for antiepileptic drugs, thereby accelerating the exploration of novel antiepileptic drug screening and improving preventive and therapeutic strategies in epilepsy research.