The sensitive detection of disease-related microRNAs in clinical samples remains a challenge requiring robust signal amplification strategies. Herein, we report an electrochemical biosensor for ultrasensitive miRNA-21 detection by integrating a catalytic hairpin assembly (CHA) circuit with a rationally designed cerium-doped bismuth fluoride-supported platinum nanoparticle composite (BiF3(Ce)@Pt). Cerium doping strategically reconstructs BiF3 into a porous architecture, enabling high-density, anti-aggregation loading of Pt nanoparticles and significantly enhancing heterogeneous electron transfer at the electrode interface. The BiF3(Ce)@Pt modified electrode exhibits exceptional electrocatalytic activity toward H2O2 reduction, as evidenced by enhanced cathodic current density and accelerated electron transfer kinetics. Serving as a powerful signal tag, BiF3(Ce)@Pt is anchored onto the electrode surface via target-initiated CHA, where each miRNA-21 recognition event triggers the assembly of multiple nanocatalysts, converting a single binding event into a substantially amplified current response. This dual-amplification strategy achieves a wide linear range from 10 fM to 5 nM and an ultra-low detection limit of 0.38 fM. The biosensor also demonstrates high specificity, excellent reproducibility, and reliable performance in human serum (recovery 101.0–101.3%). Synergizing nucleic acid amplification with advanced nanocatalysis, this work enables sensitive miRNA-21 detection and a generalizable electroanalytical paradigm for biomarker diagnostics.
Near-infrared (NIR) pre-irradiation before irreversible electroporation (IRE), or NIRE, augments apoptosis in rat stomach, but its transcriptional correlates are unknown. We profiled rat gastric corpus from four arms on the Rat Gene 2.0 ST array (n = 3 per arm; light only n = 1) in an exploratory design. Under nominal criteria (fold change at least 1.5, uncorrected p < 0.05), IRE and NIRE altered 1175 and 1365 transcripts versus control and 334 differed between NIRE and IRE. With limma moderated statistics the control contrasts gave 172 and 318 transcripts at FDR < 0.05, but none reached FDR < 0.05 for NIRE versus IRE (minimum 0.198, Nqo2), and unsupervised ordination did not separate the arms (PERMANOVA p = 0.10, an exact test floor). Against the IRE response, 64% of that signature comprised changes induced by IRE that NIRE attenuated or reversed; only 7% was amplification. Competitive gene-set tests gave a nominal, uncorrected signal for the metallothionein family (p = 0.036) and a trend toward lower NRF2/ARE targets (p = 0.057), the latter reflecting an absent IRE-associated antioxidant induction rather than suppression below control; no set survived correction, and a heat-shock panel was unchanged (p = 0.66). These are descriptive, hypothesis-generating observations that nominate candidate programs for validation; they do not establish a mechanism.
Lung cancer is one of the deadliest forms of cancer, with a significantly high mortality rate. Consequently, early diagnosis is crucial for effective treatment and improved survival outcomes. The cytokeratin 19 fragment, CYFRA 21-1, is a key biomarker for lung cancer detection and is strongly associated with non-small cell lung cancer, particularly squamous cell carcinoma. Accordingly, establishing a sensitive and reliable method for early lung cancer diagnosis based on CYFRA 21-1 detection is critical to improving clinical outcomes. This study introduces a new highly sensitive competitive electrochemical platform capable of detecting CYFRA 21-1using gold nanoparticles (AuNPs)/graphene oxide (GO)/MoO3-MoS2 nanocomposite and gold (Au) nanotags. The sensing platform is constructed by depositing CYFRA 21-1 on a AuNPs/GO/MoO3-MoS2 nanocomposite-modified screen-printed electrode (SPE). In the detection process, the electrode specifically captures unbound anti-CYFRA 21-1 on hydroquinone (HQ)@Au nanotags after competitive binding to the target CYFRA 21-1 in the sample. Our strategy for signal amplification uses the electrochemical response of HQ, anchored to nanotags, as a redox probe. The combination of three nanomaterials enhances electrode reactivity by increasing surface area and conductivity, while maintaining sufficient CYFRA 21-1 bioactivity due to the materials' biocompatibility. Quantitative analysis is achieved by the signal-off HQ peak current, which is inversely proportional to CYFRA 21-1 concentration, with two linear ranges of 0.010–5.0 and 5.0–25 ng mL−1 on a logarithmic concentration scale and a detection limit of 3.0 pg mL−1. Moreover, the sensor exhibits high specificity, reliable reproducibility, and exceptional stability. Simultaneously, the proposed competitive immunosensor can effectively detect CYFRA 21-1 in human serum samples, demonstrating good recovery. The implementation of this electrochemical biosensor offers an opportunity to develop an accurate, cost-effective, and user-friendly diagnostic tool for detecting this type of cancer.
Microbial fuel cells integrating photosynthetic microorganisms hold promise for sustainable bioelectricity generation but their operation in real matrices remains underexplored. Here, we report the development of a polydopamine-coated polyhydroxybutyrate‑carbon nanofibers electrode colonized by the purple non‑sulfur bacterium Rhodobacter capsulatus enabling simultaneous light-driven current production, CO2 sequestration, and long-term stability in real highly saline environments. Specifically, the artificial bioelectrode demonstrated high operational durability over one month of continuous fed-batch operation, maintaining stable current generation across repeated 6-day analytical cycles. Under stressful conditions (50:50 growth medium:seawater), the biophotoelectrode achieved a current density of 32±1 μA cm−2 alongside a Coulombic efficiency of 7.2±1.2%. Headspace gas chromatography analysis revealed CO2 depletion over time, with formate identified among the major products in the investigated conditions, particularly under moderate salinity (80:20 growth medium:seawater). In contrast, hydrogen evolution was detected only under high-salinity stress (50:50 growth medium:seawater), suggesting activation of alternative metabolic pathways. These findings demonstrate that R. capsulatus-modified electrodes can harness light energy and drive carbon conversion in complex saline environments. By leveraging stress-responsive metabolic flexibility and electroactive biofilm engineering, this platform paves the way for self-sustaining systems capable of simultaneous renewable electricity generation in highly saline environments, and production of value-added chemicals.
Cardiac troponin I (cTnI) represents a highly specific biomarker for the detection of myocardial infarction. To meet the demand for accurate detection of cTnI, a ratiometric electrochemical biosensor based on graphene oxide-2-aminoanthraquinone (GO-AQ) and iron-based metal-organic frameworks‑gold nanoparticles (FeMOFs-Au NPs) was developed. GO possesses a large specific surface area and favorable biocompatibility, serving as an ideal carrier for subsequent antibody immobilization. Diazotized AQ was anchored onto the surface of GO via covalent bonds to generate stable electrochemical redox signals. Owing to their stable framework structure, FeMOFs can produce inherent and stable electrochemical redox peaks. The in-situ growth of Au NPs greatly enhances the conductivity of MOFs and accelerates interfacial electron transfer. With the self-calibration mechanism, the developed sensor could detect cTnI concentrations ranging from 0.001 to 100 ng mL−1, and limit of detection was determined to be 0.36 pg mL−1. Benefiting from superior signal stability, the sensor exhibited excellent intra-batch and inter-batch reproducibility. For practical samples, the sensor showed good recovery rates (99.92%–107.8%) and could distinguish patients from healthy individuals. The detection performance of the ratiometric sensor is significantly superior to that of single-signal modes, and the obtained results are highly consistent with those measured by commercial method.
