Face-to-face Assembly Strategy of Au Nanocubes: Induced Generation of Broad Hotspot Regions for SERS-Fluorescence Dual-Signal Detection of Intracellular miRNAs.

While designing anisotropic noble metal nanoparticles (NPs) can enhance the signal intensity of Raman dyes, more sensitive surface-enhanced Raman scattering (SERS) probes can be designed by oriented self-assembly of noble metal nanomaterials into dimers or higher-order nanoclusters. In this study, we engineered a self-assembly strategy in living cells for real-time fluorescence and SERS dual-channel detection of intracellular microRNAs (miRNAs), using Mg2+-dependent 8-17E DNAzyme sequences as the driving motors, gold nanocubes (AuNCs) as the driver components, and three-branched double-stranded DNA as the linking tool. The assembly selects adenine in DNA as a reporter molecule, simplifying the labeling process of Raman reporter molecules and reducing the synthesis process. In addition, adenine is stably distributed between the faces of AuNCs and the wide hotspot region gives good reproducibility of the adenine SERS signal. In this strategy, the SERS channel was consistently stable and more sensitive compared to the fluorescence channel. Among them, the detection limit of the SERS channel was 2.1 pM and the coefficient of variation was 1.26% in the in vitro liquid phase and 1.49% in MCF-7 cells. The strategy successfully achieved accurate tracking and quantification of miRNA-21 in cancer cells, showing good reproducibility in complex samples as well as cells. The reported strategy provides ideas for exploring intracellular specific triggering of nanoparticles for precise control of self-assembly.

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

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.

DNAzyme-Powered Three-Dimensional DNA Walker Nanoprobe for Detection Amyloid ß-Peptide Oligomer in Living Cells and in Vivo.

Amyloid ß-peptide oligomer (AßO) is widely acknowledged as the promising biomarker for the diagnosis of Alzheimer's disease (AD). In this work, we designed a three-dimensional (3D) DNA walker nanoprobe for AßO detection and real-time imaging in living cells and in vivo. The presence of AßO triggered the DNAzyme walking strand to cleave the fluorophore (TAMRA)-labeled substrate strand modified on the gold nanoparticle (AuNP) surface and release TAMRA-labeled DNA fragment, resulting in the recovery of fluorescent signal. The entire process was autonomous and continuous, without external fuel strands or protease, and finally produced plenty of TAMRA fluorescence, achieving signal amplification effect. The nanoprobe enabled the quantitative detection of AßO in vitro, and the limit of detection was 22.3 pM. Given the good biocompatibility of 3D DNA walker nanoprobe, we extended this enzyme-free signal amplification method to real-time imaging of AßO. Under the microscope, nanoprobe accurately located and visualized the distribution of AßO in living cells. Moreover, in vivo imaging results showed that our nanoprobe could be used to effectively distinguish the AD mice from the wild-type mice. This nanoprobe with the advantages of great sensitivity, high specificity, and convenience, provides an outstanding prospect for AD's early diagnosis development.

An NIR-Driven Upconversion/C3N4/CoP Photocatalyst for Efficient Hydrogen Production by Inhibiting Electron-Hole Pair Recombination for Alzheimer's Disease Therapy.

Redox imbalance and abnormal amyloid protein (Aß) buildup are key factors in the etiology of Alzheimer's disease (AD). As an antioxidant, the hydrogen molecule (H2) has the potential to cure AD by specifically scavenging highly harmful reactive oxygen species (ROS) such as •OH. However, due to the low solubility of H2 (1.6 ppm), the traditional H2 administration pathway cannot easily achieve long-term and effective accumulation of H2 in the foci. Therefore, how to achieve the continuous release of H2 in situ is the key to improve the therapeutic effect on AD. As a corollary, we designed a rare earth ion doped g-C3N4 upconversion photocatalyst, which can respond to NIR and realize the continuous production of H2 by photocatalytic decomposition of H2O in biological tissue, which avoids the problem of the poor penetration of visible light. The introduction of CoP cocatalyst accelerates the separation and transfer of photogenerated electrons in g-C3N4, thus improving the photocatalytic activity of hydrogen evolution reaction. The morphology of the composite photocatalyst was shown by transmission electron microscopy, and the crystal structure was studied by X-ray diffractometry and Raman analysis. In addition, the ability of g-C3N4 to chelate metal ions and the photothermal properties of CoP can inhibit Aß and reduce the deposition of Aß in the brain. Efficient in situ hydrogen production therapy combined with multitarget synergism solves the problem of a poor therapeutic effect of a single target. In vivo studies have shown that UCNP@CoP@g-C3N4 can reduce Aß deposition, improve memory impairment, and reduce neuroinflammation in AD mice.

DNAzyme-driven bipedal DNA walker for label-free and signal-on electrochemical detection of amyloid-ß oligomer.

As a common technique for detecting AßO, the enzyme-linked immunosorbent assay (ELISA) method is time-consuming, high in cost, and poor in stability. Therefore, it is necessary to develop a highly sensitive, method-simple and low-cost method for the selective detection of AßO. Here, we created a novel signal-on and label-free electrochemical aptamer sensor for the detection of AßO based on a DNAzyme-driven DNA bipedal walking strategy. Compared with common DNA walkers, bipedal DNA walkers exhibit larger walking areas and faster walking kinetics, and provide higher amplification efficiency. The DNAwalker is powered by an Mg2+-dependent DNAzyme, and the binding-induced DNAwalker continuously clamps the MB, unlocking several active G-quadruplex-forming sequences. These G-quadruplexes can be further combined by hemin to generate a G-quadruplex/heme complex, resulting in an amperometric signal, resulting in a broad proportional band from 0.1 pM to 1 nM and an excellent detection range of 46 fM. A bipedal DNA walker aptamer sensor can detect human serum AßO with remarkable specificity, high reproducibility and practical application value.

Gold Nanorods with Spatial Separation of CeO2 Deposition for Plasmonic-Enhanced Antioxidant Stress and Photothermal Therapy of Alzheimer's Disease.

Activities of catalase (CAT) and superoxide dismutase (SOD) of ceria nanoparticles (CeO2 NPs) provide the possibility for their application in nervous system oxidative stress diseases including Alzheimer's disease (AD). The addition of hot electrons produced by a plasma photothermal effect can expand the photocatalytic activity of CeO2 to the near-infrared region (NIR), significantly improving its redox performance. Therefore, we coated both ends of gold nanorods (Au NRs) with CeO2 NPs, and photocatalysis and photothermal therapy in the NIR are introduced into the treatment of AD. Meanwhile, the spatially separate structure enhances the catalytic performance and photothermal conversion efficiency. In addition, the photothermal effect significantly improves the permeability of the blood-brain barrier (BBB) and overcomes the shortcomings of traditional anti-AD drugs. To further improve the therapeutic efficiency, Aß-targeted inhibitory peptides were modified on the middle surface of gold nanorods to synthesize KLVFF@Au-CeO2 (K-CAC) nanocomposites. We have verified their biocompatibility and therapeutic effectiveness at multiple levels in vitro and in vivo, which have a profound impact on the research and clinical transformation of nanotechnology in AD therapy.

Hybridization chain reaction triggered poly adenine to absorb silver nanoparticles for label-free electrochemical detection of Alzheimer's disease biomarkers amyloid ß-peptide oligomers.

Amyloid ß-peptide oligomer (AßO) has received extensive attention from researchers because of its clinical therapeutic intervention targets and the value of reliable biological macromolecules markers for early diagnosis of Alzheimer's disease. We have developed a novel label-free electrochemical detection sensor for AßO based on hybridization chain reaction (HCR)-triggered poly adenine to absorb silver nanoparticles (AgNPs). In this method, we first use the "capture probe" to immobilize the aptamer 1 on the surface of the gold electrode (GE) via poly adenine-Au. Next, aptamer 2 and AßO were deposited on the electrode surface. The HCR process was initiated by the aptamer 2 fragment as a primer, producing a large number of long DNA sequences, which contained many adenines. Thereafter, the HCR product with long-repeated adenines could absorb many AgNPs on the surface of the electrode, which were used for subsequent electrochemical stripping of the AgNPs. The concentration range of the electrochemical signal of AßO was 1 pM-10 nM, and the detection limit was 430 fM, which indicated that that the detection system has high selectivity for the target protein.

Carbon nitride-based nanocaptor: An intelligent nanosystem with metal ions chelating effect for enhanced magnetic targeting phototherapy of Alzheimer's disease.

Metal ions imbalance, a well-established pathologic feature of alzheimer's disease (AD), ultimately results in the deposition of amyloid-ß peptide (Aß) proteins and Aß-induced neurotoxicity. Herein, to overcome these hurdles, an intelligent Aß nanocaptor with the capacity to chelate metal ions and targeted therapy is developed by anchoring carbon nitride (C3N4) nanodots to Fe3O4@mesoporous silica nanospheres, and decorated with benzothiazole aniline (BTA) (designated as B-FeCN). The C3N4 nanodots could effectively capture superfluous Cu2+ to suppress the formation of Cu2+-Aß complex thereby eliminating Aß aggregation. Simultaneously, the nanocaptor enables local low-temperature hyperthermia to promote the dissolution of preformed fiber precipitates, therefore, maximizing the therapeutic benefits. Owing to its favorable photothermal effect, the blood-brain barrier (BBB) permeability of the nanocaptor is noticeably ameliorated upon laser illumination, which conquers the limitations associated with traditional anti-AD drugs, as evidenced by in vivo and in vitro studies. Besides, leveraging on the magnetic properties of Fe3O4 core, the nanocaptor is magnetized to access to the targeted Aß regions under extrinsic magnetic field. BTA conjugation, which specifically binds to the ß2 position of the Aß fibers, executes specific targeting at Aß plaques, and synchronously endows the BTA-modified nanocaptor with fluorescent imaging property for sensitively detecting Aß aggregates. In view of these superiorities, nanocaptors combine metallostasis restoration and Aß targeted therapy can surmount the interference of copper ions, enhance BBB permeability and protect cells against Aß-induced neurotoxicity, which provides new avenues for developing neuroprotective nanosystems for the treatment of alzheimer's disease.