Nanocages Research Articles

Ultra-sensitive and high efficiency detection of multiple non-small cell lung cancer-related miRNAs on a single test line in catalytic hairpin assembly-based SERS-LFA strip

Accurate quantification of multiple miRNAs biomarkers in body fluid is still a challenge for early screening of cancer. Herein, by catalytic hairpin assembly as a signal amplification strategy, we designed a novel surface-enhanced Raman scattering (SERS)-lateral flow assay (LFA) strip for ultrasensitive detection of miR-21 and miR-196a-5p in non-small cell lung cancer (NSCLC) urine on a single test (T) line. 4-mercaptobenzoic acid or 5,5′-dithiobis-2-nitrobenzoic acid as Raman molecules was labeled and two hairpin DNA sequence was modified gold nanocages (GNCs) were designed as two SERS tags. Through target miRNA-triggered catalytic hairpin assembly (CHA), the double-stranded DNAs (H1–H2 complex) formed by SERS tags and the related hairpin-structured DNA sequence 2 (H2) were immobilized on a single T line of SERS-LFA strip. This generated abundant “hot spots” because of the formation of numerous H1–H2 complex thus facilitated the SERS measurement. Through this method, two kinds of miRNAs were analyzed, resulting in limits of detection of 2.08 pM and 3.31 pM for miR-21 in PBS buffer and human urine, 1.77 pM and 2.18 pM for miR-196a-5p in PBS buffer and human urine. Significantly, the SERS-LFA strip exhibited high specificity and good repeatability toward miRNAs. The whole detection time was only 30 min, which means that the high detection efficiency of the strip. The clinical feasibility of the proposed method was also evaluated by detecting the levels of miR-21 and miR-196a-5p in urine samples from NSCLC patients and healthy subjects. The developed SERS-LFA strip has wide application prospect in biomedical research, drug development and early clinical diagnosis.

Lactoferrin-Bearing Gold Nanocages for Gene Delivery in Prostate Cancer Cells in vitro.

BackgroundGold nanocages have been widely used as multifunctional platforms for drug and gene delivery, as well as photothermal agents for cancer therapy. However, their potential as gene delivery systems for cancer treatment has been reported in combination with chemotherapeutics and photothermal therapy, but not in isolation so far. The purpose of this work was to investigate whether the conjugation of gold nanocages with the cancer targeting ligand lactoferrin, polyethylene glycol and polyethylenimine could lead to enhanced transfection efficiency on prostate cancer cells in vitro, without assistance of external stimulation.MethodsNovel lactoferrin-bearing gold nanocages conjugated to polyethylenimine and polyethylene glycol have been synthesized and characterized. Their transfection efficacy and cytotoxicity were assessed on PC-3 prostate cancer cell line following complexation with a plasmid DNA.ResultsLactoferrin-bearing gold nanocages, alone or conjugated with polyethylenimine and polyethylene glycol, were able to condense DNA at conjugate:DNA weight ratios 5:1 and higher. Among all gold conjugates, the highest gene expression was obtained following treatment with gold complex conjugated with polyethylenimine and lactoferrin, at weight ratio 40:1, which was 1.71-fold higher than with polyethylenimine. This might be due to the increased DNA cellular uptake observed with this conjugate, by up to 8.65-fold in comparison with naked DNA.ConclusionLactoferrin-bearing gold nanocages conjugates are highly promising gene delivery systems to prostate cancer cells.

Photothermal Response Induced by Nanocage-Coated Artificial Extracellular Matrix Promotes Neural Stem Cell Differentiation.

Strategies to increase the proportion of neural stem cells that differentiate into neurons are vital for therapy of neurodegenerative disorders. In vitro, the extracellular matrix composition and topography have been found to be important factors in stem cell differentiation. We have developed a novel artificial extracellular matrix (aECM) formed by attaching gold nanocages (AuNCs) to glass coverslips. After culturing rat neural stem cells (rNSCs) on these gold nanocage-coated surfaces (AuNC-aECMs), we observed that 44.6% of rNSCs differentiated into neurons compared to only 27.9% for cells grown on laminin-coated glass coverslips. We applied laser irradiation to the AuNC-aECMs to introduce precise amounts of photothermally induced heat shock in cells. Our results showed that laser-induced thermal stimulation of AuNC-aECMs further enhanced neuronal differentiation (56%) depending on the laser intensity used. Response to these photothermal effects increased the expression of heat shock protein 27, 70, and 90α in rNSCs. Analysis of dendritic complexity showed that this thermal stimulation promoted neuronal maturation by increasing dendrite length as thermal dose was increased. In addition, we found that cells growing on AuNC-aECMs post laser irradiation exhibited action potentials and increased the expression of voltage-gated Na+ channels compared to laminin-coated glass coverslips. These results indicate that the photothermal response induced in cells growing on AuNC-aECMs can be used to produce large quantities of functional neurons, with improved electrochemical properties, that can potentially be transplanted into a damaged central nervous system to provide replacement neurons and restore lost function.

Three‐Dimensional Visualization of Subcellular Dynamics of Cancer Cell Destruction on Therapeutic Nanodrug Treatment

Ultrastructural visualization of targeted nanoparticles against its interactions with subcellular organelles through electron microscopy and its 3D rendering is always challenging. Mechanistic and conformational understandings of specific subcellular connections of novel smart nanocarriers with various intrinsic receptors of breast cancer cells are critical for the design and delivery of novel cancer therapeutics. Toxicological effects of gold nanocages, passivated with extremophilic polysaccharide, Mauran functionalized with 4‐hydroxytamoxifen and monoclonal antibody Pr1E11 result in downright decimation of subcellular organelles in breast cancer MCF7 cells resulting in parallel type I and type II cell deaths. Herein, the deleterious repercussions of the therapeutic gold nanocages (TANs) on the subcellular organelles of MCF7 cells are studied. Confocal and transmission electron microscopic images reveal significant localization of the TANs within the mitochondria, lysosomes, and autophagosomes leading to their destruction in a span of 96 h from their incubation. The 3D electron density maps of these subcellular organelles computed using images recorded by scanning block‐face electron and transmission electron microscopes reveal a previously unknown systemic degradation process of mitochondria and the structure of autolysosome. Together, this data fortifies the benefit of subcellular cancer targeting and multiple parallel damage explained through advanced electron microscopic visualization.

Preparation of photothermal responsive and ROS generative gold nanocages for cancer therapy

• Photothermal responsive and ROS generative nanoplatform is always attracting for cancer therapy. • IR780 loaded gold nanocages using linkage of Pluronic F127 as anticancer nanoplatform were prepared. • The obtained gold nanocages could ablate the tumor with volumes as large as 1500 mm 3 of rat. The development of photothermal responsive and ROS generative nanoplatform is always attracting for cancer therapy. In this work, we propose a strategy of preparation of IR780 loaded gold nanocages using linkage of Pluronic F127 as anticancer nanoplatform (AuNCs-Plu-IR780). The obtained results showed that the AuNCs-Plu-IR780 have IR780 loading efficiency and loading content were 21.7% and 5.66%, respectively. Thermo photographic research proved that the obtained AuNCs-Plu-IR780 were photothermal responsive under near-infrared laser irradiation and remained photostability after several cycles of laser irradiation. This advantage overcomes the optical instability of IR780 and enhances the photothermal efficiency of AuNCs. MTT and cellular uptake research further proved that AuNCs-Plu-IR780 were ROS generative, and the related apoptosis of MCF-7 cells were observed. Animal experiments showed that the gathered AuNCs-Plu-IR780 reached a photothermal responsive temperature up to 89.6 °C at the tumor site, which could almost ablate the tumor with volumes as large as 1500 mm 3 without recurrence during a 20 days treatment period. These results confirm that the photothermal responsive and ROS generative AuNCs-Plu-IR780 have a brilliant prospect in the field of cancer photothermal therapy.

Comparison of Gold Nanospheres, Nanorods, Nanocages and Nanoflowers for Combined Photothermal-Radiotherapy of Cancer

Gold nanoparticles are promising dual agents for combined photothermal-radiotherapy of cancer. Nevertheless, the shape effects of gold nanoparticles on photothermal conversion efficiency and radiosensitization have not been completely revealed. To address this knowledge gap, different shapes of gold nanoparticles including gold nanospheres (GNSs), gold nanorods (GNRs), gold nanocages (GNCs) and gold nanoflowers (GNFs) were synthesized. Despite being subjected to the same modification with poly (ethylene glycol) (PEG), these gold nanoparticles showed different cellular uptake efficiencies: GNFs[Formula: see text][Formula: see text][Formula: see text]GNSs[Formula: see text][Formula: see text][Formula: see text]GNCs[Formula: see text][Formula: see text][Formula: see text]GNRs. Moreover, GNRs, GNCs and GNFs could convert near-infrared (NIR) light to heat and GNFs displayed the highest photothermal conversion efficiency, whereas GNSs showed poor photothermal effects due to the weak NIR absorption. The highest uptake efficiency as well as the best photothermal conversion ability led to GNFs to exhibit the best photothermal therapeutic effect. Furthermore, all the gold nanoparticles could be used as radiosensitizers to improve radiotherapeutic effect. Among these nanoparticles, GNFs showed the best radiation enhancement effect because of their highest uptake efficiency. Furthermore, a higher accumulation of GNFs in tumor tissues was observed than those of other shaped gold nanoparticles. Importantly, our in vitro and in vivo comparative studies revealed that GNFs possessed the strongest anticancer effect in combined photothermal-radiotherapy. Hence, compared to gold nanoparticles with other shapes, the GNFs might be more desirable dual agents for highly efficient combined photothermal-radiotherapy.

Bioactive glass-biopolymers‑gold nanoparticle based composites for tissue engineering applications

Biomaterials based on bioactive glass with gold nanoparticle composites have many applications in tissue engineering due to their tissue regeneration and angiogenesis capacities. The objectives of the study were to develop new composites using bioactive glass with gold nanospheres (BGAuSP) and gold nanocages (BGAuIND), individually introduced in alginate-pullulan (Alg-Pll) polymer, to evaluate their biocompatibility potential, and to compare the obtained results with those achieved when β-tricalcium phosphate-hydroxyapatite (βTCP/HA) replaced the BG. The novel composites underwent structural and morphological characterization followed by in vitro viability testing on fibroblast and osteoblast cell lines. Additionally, the biomaterials were subcutaneously implanted in Sprague Dawley rats, for in vivo biocompatibility assessment during 3 separate time frames (14, 30 and 60 days). The biological effects were evaluated by histopathology and immunohistochemistry. The physical characterization revealed the cross-linking between polymers and glasses/ceramics and demonstrated a suitable thermal stability for sterilization processes. The in vitro assays demonstrated adequate form, pore size of composites ranging from few micrometers up to 100 μm, while the self-assembled apatite layer formed after simulated body fluid immersion confirmed the composites' bioactivity. Viability assays have highlighted optimal cellular proliferation and in vitro biocompatibility for all tested composites. Furthermore, based on the in vivo subcutaneous analyses the polymer composites with BGAuNP have shown excellent biocompatibility at 14, 30 and 60 days, exhibiting marked angiogenesis while, tissue proliferation was confirmed by high number of Vimentin positive cells, in comparison with the polymer composite that contains βTCP/HA, which induced an inflammatory response represented by a foreign body reaction. The obtained results suggest promising, innovative, and biocompatible composites with bioactive properties for future soft tissue and bone engineering endeavours.

Au-siRNA@ aptamer nanocages as a high-efficiency drug and gene delivery system for targeted lung cancer therapy

BackgroundGene and chemical therapy has become one of the rising stars in the field of molecular medicine during the last two decades. However, there are still numerous challenges in the development of efficient, targeted, and safe delivery systems that can avoid siRNA degradation and reduce the toxicity and adverse effects of chemotherapy medicine.ResultsIn this paper, a highly efficient AS1411 aptamer modified, dsDNA and MMP-2 cleavable peptide-fabricated gold nanocage vehicle, which could load doxorubicin hydrochloride (DOX) and siRNAs to achieve a combination of tumor responsive genetic therapy, chemotherapy, and photothermal treatment is presented. Our results show that this combined treatment achieved targeted gene silencing and tumor inhibition. After nearly one month of treatment with DOX-loaded Au-siRNA-PAA-AS1411 nanoparticles with one dose every three days in mice, a synergistic effect promoting the eradication of long-lived tumors was observed along with an increased survival rate of mice. The combined genetic, chemotherapeutic, and photothermal treatment group exhibited more than 90% tumor inhibition ratio (tumor signal) and a ~ 67% survival rate compared with a 30% tumor inhibition ratio and a 0% survival rate in the passive genetic treatment group.ConclusionsThe development of nanocarriers with double-stranded DNA and MMP-2 cleavable peptides provides a new strategy for the combined delivery of gene and chemotherapy medicine. Au-siRNA-PAA-AS1411 exerts high anticancer activities on lung cancer, indicating immense potentials for clinical application.

Amplified Fluorescence by Hollow-Porous Plasmonic Assembly: A New Observation and Its Application in Multiwavelength Simultaneous Detection.

Surface plasmon coupled emission (SPCE) is a new analytical technique that provides increased and directional radiation based on the near-field interaction between fluorophores and surface plasmons but suffers from the limitation of insufficient sensitivity. The assembly of hollow-porous plasmonic nanoparticles could be the qualified candidate. After the introduction of gold nanocages (AuNCs), fluorescence signal enhancement was realized by factors over 150 and 600 compared with the normal SPCE and free space emission, respectively, with a fluorophore layer thickness of approximately 10 nm; hence, the unique enhancement of SPCE by the AuNCs effectively overcomes the signal quenching induced by resonance energy transfer (in normal SPCE). This enhancement was proven to be triggered by the superior wavelength match, the enhanced electromagnetic field, and new radiation channel and process induced by the AuNC assembly, which provides an opportunity to increase the detection sensitivity and establish an optimal plasmonic enhancement system. The amplified SPCE system was employed for multiwavelength simultaneous enhancement detection through the assembly of mixed hollow nanoparticles (AuNCs and gold nanoshells), which could broaden the application of SPCE in simultaneous sensing and imaging for multianalytes.

A novel biosensor for the ultrasensitive detection of the lncRNA biomarker MALAT1 in non-small cell lung cancer

Long non-coding RNAs (lncRNAs) have been proposed as diagnostic biomarkers for the screening of non-small cell lung cancer and monitoring disease progression. Accordingly, new, rapid, and cost-effective lncRNA biosensors that can be used clinically are urgently needed. Herein, a novel effective and ultrasensitive electrochemical biosensor was developed based on a gold nanocage coupled with an amidated multi-walled carbon nanotube (Au NCs/MWCNT-NH2)-decorated screen-printed carbon electrode (SPCE). Because of its large surface area, superior conductivity, and excellent biocompatibility, this SPCE Au NCs/MWCNT-NH2 lncRNA biosensor showed a wide linear range (10–7–10–14 M) and low limit of detection limit (42.8 fM) coupled with satisfactory selectivity and stability. Compared to traditional RT-PCR, the proposed method exhibits acceptable stability, good selectivity, is simpler to operate, has faster detection, and uses less costly raw materials. In summary, this biosensor may be a powerful tool for detecting lncRNAs for efficient clinical prognosis and cancer diagnosis.

3D Taraxacum-like porous Pd nanocages with Bi doping: High-performance non-Pt electrocatalysts for ethanol oxidation reaction

Modifying the electronic structure and optimizing the geometric structure can expeditiously tune the electrocatalytic properties of catalysts, resulting in considerably enhanced electrocatalytic performance towards electrocatalytic oxidation of liquid fuels. We herein report a simple synthetic strategy to prepare Bi-doped 3D taraxacum-like Pd nanocages (NCs) composed of porous nanosheets, which possess high surface areas and strong synergistic effects. Notably, a trace of Bi diffuses into the lattice of Pd and increases the electronic effects of the surface of Pd, endowing PdBi-0.5 NCs/C with superior electrocatalytic performance towards ethanol oxidation reaction (EOR). The mass activity and specific activity of PdBi-0.5 NCs/C were 3494.8 mA mgPd−1 and 10.37 mA cm−2, being 4.08- and 4.82- fold enhancements as compared with commercial Pd/C, respectively. Moreover, the highly open porous 3D nanocages structure with rich active sites and defects can also facilitate the mass/electron transfer to favor the EOR kinetics.

Colorimetric determination of amyloid-β peptide using MOF-derived nanozyme based on porous ZnO-Co3O4 nanocages.

A sensitive and rapid colorimetric biosensor has been developed for determination of amyloid-β peptide (Aβ) and study ofamyloidogenesis based on the high peroxidase-like activity of porous bimetallic ZnO-Co3O4 nanocages (NCs). Due to the high binding ability of Aβ monomer to ZnO-Co3O4 NCs, the catalytic activity of ZnO-Co3O4 NCs can be significantly suppressed by Aβ monomer. This finding forms the basis for a colorimetric assay for Aβ monomer detection. The detection limit for Aβ monomer is 3.5nM with a linear range of 5 to 150nM (R2 = 0.997). The system was successfully applied to the determination of Aβ monomer in rat cerebrospinal fluid. Critically, the different inhibition effects of monomeric and aggregated Aβ species on the catalytic activity of ZnO-Co3O4 NCs enabled the sensor to be used for tracking the dynamic progress of Aβ aggregation and screening Aβ inhibitors. Compared with the commonly used thioflavin T fluorescence assay, this method provided higher sensitivity to the formation of Aβ oligomer at the very early assembly stage. Our assay shows potential application in early diagnosis and therapy of Alzheimer's disease (AD).

The Impact of Composites with Silicate-Based Glasses and Gold Nanoparticles on Skin Wound Regeneration.

The silver content of the skin regeneration ointments can influence its regeneration process but in the meantime, it can take the benefit of the antibacterial properties of silver by avoiding the bacterial infection of an open wound. In the current study, the skin healing and regeneration capacity of bioactive glass with spherical gold nanocages (BGAuIND) in the Vaseline ointments were evaluated in vivo comparing the bioactive glass (BG)-Vaseline and bioactive glass with spherical gold (BGAuSP)-Vaseline ointments. Spherical gold nanocages are stabilized with silver and as a consequence the BGAuIND exhibits great antibacterial activity. Histological examination of the cutaneous tissue performed on day 8 indicates a more advanced regeneration process in rats treated with BGAuSP-Vaseline. The histopathological examination also confirms the results obtained after 11 days post-intervention, when the skin is completely regenerated at rats treated with BGAuSP-Vaseline compared with the others groups where the healing was incomplete. This result is also confirmed by the macroscopic images of the evolution of wounds healing. As expected, the silver content influences the wound healing process but after two weeks, for all of the post-interventional trials from the groups of rats, the skin healing was completely.

Radiolabeling of Gold Nanocages for Potential Applications in Tracking, Diagnosis, and Image-Guided Therapy.

Gold nanocages (AuNCs) have emerged as a novel class of multifunctional nanomaterials with an array of applications in nanomedicine, including drug delivery, controlled release, as well as disease diagnosis and treatment. Labeling AuNCs with radionuclides not only offers additional therapeutic capabilities but also makes it easy to analyze their biodistribution, monitor their uptake by the tissue or organ of interest, and optimize their performance in both diagnosis and treatment. Here, an introduction to the chemical synthesis and optical properties of AuNCs is provided in the beginning. The methods developed for their radiolabeling are then showcased, followed by the use of radiolabeled AuNCs in tracking and quantifying their pharmacokinetics, including biodistribution, tumor uptake, and intratumoral distribution. Finally, their potential applications in targeted imaging and image-guided therapy are discussed.

Bi-functional gold nanocages enhance specific immunological responses of foot-and-mouth disease virus-like particles vaccine as a carrier and adjuvant

Virus-like particle (VLP) vaccines have become one of the dominant vaccine candidates for foot-and-mouth disease (FMD). To further enhance the immunogenicity of VLP vaccines, gold nanocages (AuNCs) were selected as an adjuvant for the vaccine. Our experiments demonstrated that AuNCs had little biotoxicity in vivo and in vitro and improved the uptake of VLP in BHK-21 and RAW264.7 cell lines. The VLP-AuNCs activated DCs mainly through toll-like receptor 4 (TLR4) and promoted the secretion of IL-6, IL-1β, and TNF-α. The conjugation of VLP and AuNCs triggered a strong immune response against FMD virus (FMDV) in mice and guinea pigs. The VLP-AuNCs significantly enhanced the proliferation of CD8+ T cells (P < 0.05) and the secretion of cellular immune-related cytokines (IFN-γ, P < 0.05; IL-12p70, P < 0.01) compared with VLP. The present study demonstrated that AuNCs, as a great potential adjuvant for FMDV VLP vaccines, significantly enhance the immune response.

Multiple-mRNA-controlled and heat-driven drug release from gold nanocages in targeted chemo-photothermal therapy for tumors.

Multifunctional drug delivery systems enabling effective drug delivery and comprehensive treatment are critical to successful cancer treatment. Overcoming nonspecific release and off-target effects remains challenging in precise drug delivery. Here, we design triple-interlocked drug delivery systems to perform specific cancer cell recognition, controlled drug release and effective comprehensive therapy. Gold nanocages (AuNCs) comprise a novel class of nanostructures possessing hollow interiors and porous walls. AuNCs are employed as a drug carrier and photothermal transducer due to their unique structure and photothermal properties. A smart triple-interlocked I-type DNA nanostructure is modified on the surface of the AuNCs, and molecules of the anticancer drug doxorubicin (DOX) are loaded as molecular cargo and blocked. The triple-interlocked nanostructure can be unlocked by binding with three types of tumor-related mRNAs, which act as “keys” to the triple locks, sequentially, which leads to precise drug release. Additionally, fluorescence-imaging-oriented chemical–photothermal synergistic treatment is achieved under illumination with infrared light. This drug delivery system, which combines the advantages of AuNCs and interlocked I-type DNA, successfully demonstrates effective and precise imaging, drug release and photothermal therapy. This multifunctional triple-interlocked drug delivery system could be used as a potential carrier for effective cancer-targeting comprehensive chemotherapy and photothermal therapy treatments.

A petal-shaped MOF assembled with a gold nanocage and urate oxidase used as an artificial enzyme nanohybrid for tandem catalysis and dual-channel biosensing

A facile one-pot precipitation method was employed to prepare a petal-shaped hybrid under mild conditions. The hybrid is composed of urate oxidase (UOx) encapsulated into a zeolite-like metal-organic framework (MOF) with the doping of a hollow gold nanocage (AuNC). As one of the MOF-enzyme composites, a UOx@MOF(AuNC) hybrid with the features of artificial nanoenzymes was developed as a novel dual-channel biosensing platform for fluorescence (FL) and electrochemical detection of uric acid (UA). As for FL biosensing, enzymatic catalysis of the hybrid in the presence of UA triggered tandem catalysis and oxidation reactions to cause FL quenching. UA was linearly detected in the 0.1-10 μM and 10-300 μM ranges, with the limit of detection (LOD) of 20 nM. As for electrochemical biosensing, the hybrid was dropped on a glassy carbon electrode (GCE) surface to construct a hybrid/GCE platform. Based on the redox reaction of UA on the platform surface, UA was linearly detected in the 0.05-55 μM range, with a LOD of 15 nM. Experimental results confirmed that the hybrid-based dual-channel biosensing platform enabled selective and sensitive responses to UA over potential interferents. The platform has an excellent detection capability in physiological samples. The dual-channel biosensing platform facilitates the exploration of new bioanalysis techniques for early clinical diagnosis of diseases.

基于金纳米笼和MoS2的1 123 nm被动调Q Nd: YAG激光器

基于金纳米笼和MoS2的1 123 nm被动调Q Nd: YAG激光器

Versatile template-directed synthesis of gold nanocages with a predefined number of windows.

Highly symmetrical gold nanocages can be produced with a controllable number of circular windows of either 2, 3, 4, 6 or 12 via an original fabrication route. The synthetic pathway includes three main stages: the synthesis of silica/polystyrene multipod templates, the regioselective seeded growth of a gold shell on the unmasked part of the silica surface and the development of gold nanocages by dissolving/etching the templates. Electron microscopy and tomography provide evidence of the symmetrical features of the as-obtained nanostructures. The optical properties of nanocages with 4 and 12 windows were measured at the single particle level by spatial modulation spectroscopy and correlated with numerical simulations based on finite-element modeling. The new multi-step synthesis approach reported here also allows the synthesis of rattle-like nanostructures through filling of the nanocages with a guest nano-object. With the potential to adjust the chemical composition, size and geometry of both the guest particle and the host cage, it opens new routes towards the fabrication of hollow nanostructures of high interest for a variety of applications including sensing devices, catalytic reactors and biomedicine.

DNAzyme-catalyzed etching process of Au/Ag nanocages visualized via dark-field imaging with time elapse for ultrasensitive detection of microRNA

Abstract Dark-field imaging techniques based on the localized surface plasmon resonance (LSPR) of metal nanoparticles provide new insights for real-time monitoring of dynamic reaction processes at single particle level. In this work, the Au/Ag nanocages (NCs) are employed as optical plasmon probes for microRNA detection based on visualized scattering signal changes. Induced by DNAzyme-catalyzed etching process, the scattering signals of plasmon probe “turns-off” due to the decreased silver proportion of Au/Ag NCs with time elapse. The dynamic process is monitored under dark-field microscopy, in which the waiting time that elapsed before a nanocage stochastically disappeared is found directly related to the concentration of the target microRNA. Combined with the strand displacement and hybridization cascade amplification strategy, the concentration of microRNA-21 in cell lysate is determined by statistical analysis with high sensitivity and selectivity. The proposed dark-field scattering biosensing based on nanocage probes is convenient for accurately judging end-point during real time monitoring over time, and provides a novel strategy for the development of biosensing at single particle level.