Imaging of tumor-associated microRNAs (miRNAs) can provide abundant information for cancer diagnosis, whereas the occurrence of trace amounts of miRNAs in normal cells inevitably causes an undesired false-positive signal in the discrimination of cancer cells during miRNA imaging. In this study, we propose a dual-locked (D-locked) platform consisting of the enzyme/miRNA-D-locked DNAzyme sensor and the honeycomb MnO2 nanosponge (hMNS) nanocarrier for highly specific cancer cell imaging. For a proof-of-concept demonstration, apurinic/apyrimidinic endonuclease 1 (APE1) and miR-21 were chosen as key models. The hMNS nanocarrier can efficiently release the D-locked DNAzyme sensor in living cells due to the decomposition of hMNS by glutathione, which can also supply Mn2+ for DNAzyme cleavage. Ascribing to the smart design of the D-locked DNAzyme sensor, the fluorescence signal can only be generated by the synergistic response of APE1 and miR-21 that are overexpressed in cancer cells. Compared with the miRNA single-locked DNAzyme sensor and the small-molecule (ATP)/miRNA D-locked DNAzyme sensor, the proposed enzyme (APE1)/miRNA D-locked DNAzyme sensor exhibited 2.6-fold and 2.4-fold higher discrimination ratio (Fcancer/Fnormal) for cancer cell discrimination, respectively. Owing to the superior performance, the D-locked strategy can selectively generate a fluorescence signal in cancer cells, facilitating accurate discrimination of cancer both in vitro and in vivo. Furthermore, this D-locked platform is easily adaptable toward other target molecules by redesigning the DNA sequences. The outstanding performance and expansibility of this D-locked platform holds promising prospects for cancer diagnosis and related biomedical applications.

Dual-Locked DNAzyme Platform for In Vitro and In Vivo Discrimination of Cancer Cells.

Covalent organic framework-based fluorescent nanoprobe for intracellular pH sensing and imaging.

The fabrication of multifunctional photosensitizers (PSs) with abundant Type I/II ROS for efficient theranostics in the "therapeutic window" (700-900 nm) is an appealing yet significantly challenging task. We herein report a molecular tailoring strategy based on intramolecular two-photon Forster Resonance Energy Transfer (TP-FRET) to obtain a novel theranostic agent (Lyso-FRET), featuring the amplified advantage of energy donor (NH) and acceptor (COOH), because of the reuse of fluorescence energy with high efficiency of FRET (∼83%). Importantly, under the excitation by the near-infrared (840 nm) window, Lyso-FRET can not only penetrate the deeper tissue with a higher resolution for fluorescence imaging due to the nonlinear optical (NLO) nature, but also generate more Type I (superoxide anion) and Type II (singlet oxygen) reactive oxygen species for hypoxic PDT. Moreover, Lyso-FRET targeting lysosomes further promotes the effect of treatment. The experiments in vitro and in vivo also verify that the developed TP-FRET PS is conducive to treating deep hypoxic tumors. This strategy provides new and significant insights into the design and fabrication of advanced multifunctional PSs.

Molecular Tailoring Based on Forster Resonance Energy Transfer for Initiating Two-Photon Theranostics with Amplified Reactive Oxygen Species.

The localization of isothermal amplification systems has elicited extensive attention due to the enhanced reaction kinetics when detecting ultra-trace small-molecule nucleic acids. Therefore, the seek for an appropriate localization cargo of spatially confined reactions is urgent. Herein, we have developed a novel approach to localize the catalytic hairpin assembly (CHA) system into the DNA tile self-assembly nanostructure. Thanks to the precise programming and robust probe loading capacity, this strategy achieved a 2.3 × 105-fold higher local reaction concentration than a classical CHA system with enhanced reaction kinetics in theory. From the experimental results, this strategy could reach the reaction plateau faster and get access to a magnified effect of 1.57-6.99 times higher in the linear range of microRNA (miRNA) than the simple CHA system. Meanwhile, this strategy satisfied the demand for the one-step detection of miRNA in cell lysates at room temperature with good sensitivity and specificity. These features indicated its excellent potential for ultra-trace molecule detection in clinical diagnosis and provided new insights into the field of bioassays based on DNA tile self-assembly nanotechnology.

Kinetics-accelerated one-step detection of MicroRNA through spatially localized reactions based on DNA tile self-assembly.

Kinetics-accelerated one-step detection of MicroRNA through spatially localized reactions based on DNA tile self-assembly

Compared with the single-marker detection scheme, the detection of multiple targets in the complex cell and biological environment can obtain more reliable detection results. Herein, we detected miRNA-21 and APE1 in two modes, AND and OR, respectively, based on gold nanoflares and simple logic components. In both modes, DNAzyme and APE1 can get rich fluorescence recovery results by breaking the DNA strands from the gold nanorods (AuNRs) and unquenching under different conditions. In vivo and in vitro experiments suggest that both nanoflares exhibit excellent biocompatibility and make efficient and sensitive judgments on the two targets. This strategy emphasizes the reuse nature of enzymes, and a small amount of target can generate a large amount of fluorescent signal in the logic device, which greatly reduces the detection limit when monitoring low-abundance targets. Since the short-stranded DNA component of the detection device is simple in composition and easy to program its probe sequence, it can be expanded into a detection system for the detection of other sets of related markers, which increases its potential for clinical application.

Smart Programmable Scalable Dual-Mode Diagnostic Logic Nanoflare Strategy for Dual-Tumor Marker Detection.

Despite several attempts, incorporating biological detection that supplies necessary biological information into therapeutic nanotheranostics for hypoxic tumor treatments is considered to be in its infancy. It is therefore imperative to consolidate biological detection and desirable phototherapy into a single nanosystem for maximizing theranostic advantages. Herein, we develop a versatile nanoprobe through combined fluorescence resonance energy transfer (FRET) and oxygen-augmenting strategy, namely APT, which enables glycosylation detection, O2 self-sufficiency, and collaborative phototherapy. Such APT nanoprobes were constructed by depositing platinum onto gold nano-bipyramids (Au NBPs), linking FITC fluorophore-labeled AS1411 aptamers for introducing FRET donors, and by conjugating G-quadruplex intercalated with TMPyP4 to their surfaces via the SH-DNA chain. By installing FRET acceptors on the glycan of targeted EpCAM glycoprotein using the metabolic glycan labeling and click chemistry, FRET signals appear on the cancerous cell membranes, not normal cells, when donors and acceptors are within an appropriate distance. This actualizes protein-specific glycosylation visualization while revealing glycan-based changes correlated with tumor progression. Interestingly, the deposited platinum scavenges excessive H2O2 as artificial nanoenzymes to transform O2 that alleviates tumor hypoxia and simultaneously elevates singlet oxygen (1O2) for inducing cancer cell apoptosis. Notably, the significant hyperthermia devastation was elicited via APT nanoprobes with phenomenal photothermal therapy (PTT) efficiency (71.8%) for thermally ablating cancer cells, resulting in synergistically enhanced photodynamic-hyperthermia therapy. Consequently, APT nanoprobes nearly actualized thorough tumor ablation while demonstrating highly curative biosafety. This work offers a new paradigm to rationally explore a combined FRET and oxygen-augmenting strategy with a focus on nanotheranostics for hypoxic tumor elimination.

Gold-Bipyramid-Based Nanothernostics: FRET-Mediated Protein-Specific Sialylation Visualization and Oxygen-Augmenting Phototherapy against Hypoxic Tumor.

In view of galactose as an essential marker in the diagnosis of galactosemia that affects newborns, a rapid and effective method for galactose detection is necessary. Herein, we provide a facile colorimetric biosensor for galactose detection by combining the ternary Ag-Cu2O/Ti3C2 heterostructure and galactose oxidase (Gal Ox). A series of tests showed the Ag-Cu2O/Ti3C2 nanozyme prepared by depositing truncated octahedral Ag-Cu2O on single-layer Ti3C2 nanosheets in a simple one-pot water bath procedure exhibited moderately higher peroxidase-like activity than either pure Ti3C2 nanosheets or binary Cu2O/Ti3C2. Gal Ox can catalyze the oxidation of galactose to yield H2O2, and Ag-Cu2O/Ti3C2 nanocomposites subsequently trigger a reaction between H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB), accompanied by a significant increase in absorbance at 652 nm. Under optimal conditions, the linear range of galactose is 30–600 μM, with a detection limit of 0.99 μM. Galactose was successfully detected in human serum using the stated method in agreement well with hospital results. Furthermore, we used the designed system to construct portable agarose gel-based assay kits and realized a linear detection ranging from 50 to 500 μM, demonstrating the feasibility of the on-site detection of galactose semiquantitatively and visually in human serum in conjunction with the ImageJ program. 

A novel ternary Ag-Cu2O/Ti3C2 heterostructure with high peroxidase-like activity for on-site colorimetric detection of galactose

In the case of Parkinson’s disease (PD), the soluble α-synuclein (α-syn) oligomer is considered to be a reliable molecular biomarker. Developing easy-to-prepare, cheap, sensitive, and reliable techniques for the detection of α-synuclein oligomers is therefore a vital task. In this work, based on Mg2+-dependent DNAzyme (MNAzyme) -driven tripedal DNA walker tactics, we designed an innovative label-free and signal-on electrochemical aptasensor for α-syn oligomer quantification. α-syn oligomer-triggered tripedal DNA walkers outperformed common DNA walkers with the larger area of walking and accelerated walking kinetics, and facilitated greater amplification efficiency. With the assistance of MNAzyme, free-running tripedal DNA walkers could rapidly and continually scissor DNA hairpins (HPs), thereby unlocking numerous active G-quadruplex-forming sequences. Afterwards, G-quadruplex/hemin complexes could be formed by hemin further recognizing these G-quadruplexes and generated an enhanced current signal. Benefiting from tripedal DNA walker and MNAzyme dual signal amplification, we achieved a superior detection limit of 0.46 fM as well as a broad linear range of 1 fM to 10 pM. After being applied to α-syn oligomer detection in human serum samples, this novel electrochemical aptasensor demonstrated a high degree of sensitivity, anti-interference, and reproducibility, indicating its great potential for bioanalysis in complex biological environments. 

Mengying Fu

Papers

Smart Programmable Scalable Dual-Mode Diagnostic Logic Nanoflare Strategy for Dual-Tumor Marker Detection.

Gold-Bipyramid-Based Nanothernostics: FRET-Mediated Protein-Specific Sialylation Visualization and Oxygen-Augmenting Phototherapy against Hypoxic Tumor.

A novel ternary Ag-Cu2O/Ti3C2 heterostructure with high peroxidase-like activity for on-site colorimetric detection of galactose

DNAzyme-driven tripedal DNA walker mediated signal-on and label-free for electrochemical detection of α-synuclein oligomers

Fe-doped NiO nanoarray interlayer-modified Pd/Ni foam cathode for enhanced electrocatalytic hydrodechlorination