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Graphdiyne oxide quantum dots (GDYO QDs), as derivatives of graphdiyne (GDY), have excellent electroconductibility and luminous properties and can be applied as a new ECL emitter. Herein, an electrochemiluminescence (ECL) biosensor for miRNA-21 ultrasensitive determination is constructed based on AuNPs/GDY, GDYO QD and oligonucleotide signal amplification strategy that integrates DNA walker and hybridization chain reaction (HCR) amplification. As electrode substrate material, AuNPs/GDY can not only bond with the aptamer CP but can also enhance the conductivity of the interface. When miRNA-21 exists, the DNA walker process is initiated, and the signaling probes are introduced on the electrode surface, producing abundant double-stranded H1/H2; then, H3/H4 undergoes complementary base pairing with H1/H2 through HCR. With the increase in miRNA-21, the 3D DNA nanomachine is actively manipulated, resulting in a gradual increase in ECL signal. This ECL biosensor demonstrates outstanding performance in the determination of miRNA-21 in the linear range from 0.1 fM to 1 nM. This study offers a new sensitive idea for the clinical analysis of cancer biomarkers. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) is an sp and sp2 co-hydrocarbon allotrope whose particular structure endows it with many fascinating properties, including abundant chemical bonds, high conjugation, natural pores, high carrier mobility, high conductivity and stability, etc. In this work, two-dimensional graphdiyne is prepared as an electrode substrate material coupling with an exonuclease III-assisted amplification strategy to construct a superior-performance self-powered biosensor based on enzymatic biofuel cells for highly sensitive detection of the tumour marker miRNA-21. Glucose oxidase (GOD) is first immobilized on the GDY/AuNP composite to prepare a bioconjugate. GDY/AuNP modified carbon cloth is used as an enzyme biofuel cell electrode, which is then modified with bilirubin oxidase as a biocathode. The bioconjugate binds to GOD through specific binding to the bioanode. When miRNA-21 is present, specific recognition by exonuclease III in the system results in cleavage of the capture probe, and miRNA-21 is recovered and involved in the cycle. The target miRNA-21 then causes corresponding changes in the open-circuit voltage of the self-powered system. Based on this, a sensitive detection method was constructed, within the scope from 0.1 fM to 0.1 nM with a shallow detection limit of 55.2 aM (S/N = 3). The new approach triumphantly has been used to detect miRNA-21 in serum, which provides a compelling new way for early diagnosis of related cancers. [ABSTRACT FROM AUTHOR]

Thalassemia is a globally prevalent single-gene blood disorder, with nearly 7% of the world's population being carriers. Therefore, the development of specific and sensitive methods for thalassemia detection holds significant importance. Herein, a sandwich-type electrochemical/colorimetric dual-mode biosensor is developed based on gold nanoparticles (AuNPs)/graphdiyne (GDY) and DNA nanoframeworks for ultra-sensitive detection of CD142 gene associated with sickle cell anemia. Utilizing AuNPs/GDY as the substrate electrode, the fabricated sandwiched DNA nanoframework not only improves selectivity but also introduces numerous signal probes to further amplify the output signal. In the electrochemical mode, glucose oxidase catalyzes the oxidation of glucose, generating electrons that are transferred to the biocathode for a reduction reaction, resulting in an electric signal proportional to the target concentration. In the colorimetric mode, glucose oxidase catalyzes the generation of H 2 O 2 from glucose, and with the aid of horseradish peroxidase, H 2 O 2 oxidizes 3,3′,5,5′-tetramethylbenzidine to produce a colored product, enabling colorimetric detection of the target. The dual-mode biosensor demonstrates a detection range of 0.0001–100 pM in the electrochemical mode and a detection range of 0.0001–10,000 pM in the colorimetric mode. The detection limit in the electrochemical mode is determined to be 30.4 aM (S/N=3), while in the colorimetric mode is of 35.6 aM (S/N=3). This dual-mode detection achieves ultra-sensitive detection of CD142, demonstrating broad prospects for application. [ABSTRACT FROM AUTHOR]

• Smartphone-assisted self-powered sensor is developed for Ultra-sensitive detection of microRNA. • Binary 3D DNA Walkers combined with CRISPR/Cas12a system greatly enhances the sensitivity of biosensor. • Integrated capacitors amplify detection signal, enhancing sensitivity by 20.7-fold. • The dual-mode detection strategy significantly enhances the accuracy of the method. Malignant tumors are significant diseases that pose a threat to human life and health. The advancement of highly sensitive and specific methods is of excellent significance. This study proposes a novel detection platform that employs a smartphone-assisted self-powered sensing system with binary 3D DNA Walkers mediated CRISPR/Cas12a system and ultra-thin 2D graphdiyne for ultrasensitive dual-mode detection of breast cancer biomarker microRNA-let-7a. The binary 3D DNA Walkers possess high efficiency in movement and multifunctional characteristics. When combined with the CRISPR/Cas12a system, they can retain the advantages of 3D DNA Walker while releasing a large of trigger strands complementary to CRISPR RNA, thereby greatly enhancing the sensitivity of the sensor. In addition, capacitors are also integrated into the sensing system to further amplify the detection signal, resulting in a 20.7-fold increase in sensitivity of the method. Additionally, the adoption of an electrochemical/colorimetric dual-mode detection strategy significantly enhances the accuracy of the new approach. The newly developed detection method exhibits a linear range of 0.0001–10000 pM with a detection limit of 8.11 aM (S/N = 3). This work offers a reliable portable sensor for sensitive and accurate detection of tumor biomarkers, enabling remote disease sensing and on-site monitoring applications. [ABSTRACT FROM AUTHOR]

The latest research shows that the expression level of microRNA-141 can predict the number of prostate cancer cells in the human body and has become an important biomarker. In this paper, an all-carbon sandwich self-powered biosensor based on graphene and carbon cloth is constructed for the highly sensitive detection of the prostate tumor marker miRNA-141. First, gold nanoparticles modified carbon cloth is applied for substrate electrode, and bilirubin oxidase is then immobilized on it to prepare the biocathode of the biofuel cell. Then, aptamer 1 is immobilized on gold nanoparticles-modified carbon cloth as the electrode substrate. The bioconjugate is prepared by immobilizing the aptamer 2-glucose oxidase complex on gold nanoparticles/graphene. In the biofuel cell-based self-powered sensing system, when the target microRNA-141 is present, it undergoes complementary base pairing with aptamer 1 and aptamer 2, and the bioconjugates are immobilized on the anode to form the sandwich structure. The enzyme on the anode undergoes an oxidation reaction to catalyze the reduction of oxygen, and the electrochemical respond of the system increases significantly. The results show that the concentration of microRNA-141 is proportional to the open-circuit voltage value ranging from 0.0001 to 1000 pmol/L with a detection limit of 50 amol/L (S/N = 3). The method has high sensitivity and excellent selectivity and can be applied to sensitively detect tumor marker microRNA-141 in biological matrix. [Display omitted] • A sensitive self-powered biosensor is developed for detection of microRNA-141 with a all-carbon architecture. • The sandwich type signal amplification greatly improves the output signal and selectivity of detection. • The biosensor has wide linear range of 0.1 fM∼1 nM and low detection limit of 50 aM. [ABSTRACT FROM AUTHOR]