The Compact Integration of Multiple Exonuclease III-Assisted Cyclic Amplification Units for High-Efficiency Ratiometric Electrochemiluminescence Detection of MRSA.

Methicillin-resistant Staphylococcus aureus (MRSA) exhibits multiresistance to a plethora of antibiotics, therefore, accurate detection methods must be employed for timely identification to facilitate effective infection control measures. Herein, we construct a high-efficiency ratiometric electrochemiluminescent (ECL) biosensor that integrates multiple exonuclease (Exo) III-assisted cyclic amplification units for rapid detection of trace amounts of MRSA. The target bacteria selectively bind to the aptamer, triggering the release of two single-stranded DNAs. One released DNA strand initiates the opening of a hairpin probe, inducing exonuclease cleavage to generate a single strand that can form a T-shaped structure with the double strand connecting the oxidation-reduction (O-R) emitter of N-(4-aminobutyl)-N-ethylisoluminol gold (ABEI-Au). Consequently, ABEI-Au is released upon Exo III cleavage. The other strand unwinds the hairpin DNA structure on the surface of the reduction-oxidation (R-O) emitter ZIF-8@CdS, facilitating the subsequent release of a specific single strand through Exo III cleavage. This process effectively anchors the cathode-emitting material to the electrode. The Fe(III) metal-organogel (Fe-MOG) is selected as a substrate, in which the catalytic reduction of hydrogen peroxide by Fe(III) active centers accelerates the generation of reactive oxygen species and enhances signals from both ABEI-Au and ZIF-8@CdS. In this way, the two emitters cooperate to achieve bacterial detection at the single-cell level, and a good linear range is obtained in the range of 100-107 CFU/mL. Moreover, the sensor exhibited excellent performance in detecting MRSA across various authentic samples and accurately quantifying MRSA levels in serum samples, demonstrating its immense potential in addressing clinical bacterial detection challenges.

Cyclic Enzymatic Signal Amplification-Driven DNA Logic Nanodevices on Framework Nucleic Acid for Highly Sensitive Electrochemiluminescence Detection of Dual Myocardial miRNAs.

MicroRNAs (miRNAs) have emerged as promising biomarkers for acute myocardial infarction (AMI). There is an urgent imperative to develop analytical methodologies capable of intelligently discerning multiple circulating miRNAs. Here, we present a dual miRNA detection platform for AMI using DNA logic gates coupled with an electrochemiluminescence (ECL) response. The platform integrates DNA truncated square pyramids as capture probes on gold-deposited electrodes, enabling precise quantification of miRNA associated with AMI. The cyclic enzymatic signal amplification principle of strand displacement amplification enhances the miRNA detection sensitivity. AND and OR logic gates have been successfully constructed, enabling intelligent identification of miRNAs in AMI. Calibration curves show strong linear correlations between ECL intensity and target miRNA concentration (10 fM to 10 nM), with excellent stability in consecutive measurements. When applied to clinical serum samples, the biosensor exhibits consistent performance, underscoring its reliability for clinical diagnostics. This innovative approach not only demonstrates DNA nanotechnology's potential in biosensing but also offers a promising solution for improving AMI diagnosis and prognosis through precise miRNA biomarker detection.