Liqiang Luo

DNA walkers can drive nucleic acids to move along designed tracks or processes in DNA circuits, endowing the circuits with highly efficient signal-amplification capability. However, their actuation and movement are difficult to regulate, and integrating them into circuits for high-throughput detection remains challenging. In this work, we propose a novel DNA nanomachine termed “DNA stalker”, which can both actuate and regulate the movement of DNA walker while conferring multiplex detection capability to the entire circuit. Herein, DNA stalker can regulate DNA walker via target-responsive catalytic hairpin assembly, and thereafter be integrated with MXene to fabricate the MXene-supported DNA circuits. These DNA circuits operate in an enzyme-free manner, and the inherent limitations of current DNA walkers are overcome solely through rational nucleic acid sequence design. In addition, program-customized design enables the tailored fabrication of the MXene-supported DNA circuits according to the customer-specified target combinations to be detected, without requiring prior knowledge of nucleic acid sequence design when the detection targets are switching. To meet the requirement of clinic detection, a microfluidic device is employed to operate three circuit sets with independent outputs simultaneously, enabling the concurrent detection of six miRNAs in serum samples from healthy individuals and patients with three different types of cancer (breast, cervical and lung cancer). This system achieves highly sensitive and high-throughput detection of miRNAs in serum, providing a powerful tool for the early clinical diagnosis of cancer at the molecular level.

Single-atom nanozymes (SANs) with atomically dispersed metal sites show great potential in small biomolecule detection. This review first summarizes SAN synthesis (wet chemistry, atomic layer deposition, etc.), structural features (tunable coordination, metal-carrier interactions), and catalytic mechanisms (synergistic effects, d-band modulation). Afterwards, this review focuses on the applications of SANs in detecting small biomolecules, including glucose, glutathione, uric acid, ascorbic acid, hydrogen peroxide, and dopamine via colorimetry, fluorescence, and electrochemistry. Challenges such as matrix interference and stability, along with future directions in flexible electronics and clinical translation, are discussed, aiming to advance SAN-based detection technologies.

Diagnosing cancer at the molecular level enables patients to receive life-saving treatments in a timely manner, but sensitivity, specificity, and high-throughput analyses of tumor markers are still great challenges. To address these issues, we developed an enzyme-free DNA logic circuit named CHA-Linkage, based on catalytic hairpin assembly (CHA) and graphene oxide (GO). Three different cancer cell microRNAs (miRNA) were chosen as "AND-OR" gate inputs, and three corresponding fluorescent signals were used as the outputs. Computer-customized design (CCD) allows customers to tailor CHA-Linkage circuit elements with regard to specific target combinations according to the identification needs of different cells, effectively avoiding sequence interference between circuit elements and providing an effective tool for high-throughput miRNA detection. Herein, GO is chosen as a carrier to deliver the CHA-Linkage circuit into cells as well as to quench the fluorescence. The developed CHA-Linkage features high sensitivity, high specificity, and high throughput. More importantly, the "open circuit" and "repair" within the CHA-Linkage system are simulated, allowing further differentiation of diverse cell types. This work enables precise identification of specific cancer cell types at the molecular level, offering a powerful tool for early cancer diagnosis and therapy.

We herein report a novel method for microRNA detection by exploring the nanoimpact electrochemistry (NIE) effect of DNA-modified gold nanoparticles (AuNPs). A target-catalyzed hairpin assembly reaction is designed prior to the single-particle electrochemical collision. Direct electro-oxidation of AuNPs is utilized as the signal source, which is initially inhibited by the capped hairpin structured DNA strands. In the presence of target microRNA, catalyzed hairpin assembly occurs, forming rigid three-way junction nanostructures. Since the hairpins are consumed, they can no longer block current transmission, and the AuNP-impact electrochemical signal is restored to reveal the concentration of microRNA. This NIE-based electrochemical biosensor is nontoxic, simple to operate, and exhibits high detection sensitivity and selectivity. It can be further utilized in the clinically relevant diagnosis.