Hairpin-Hairpin Molecular Beacon Interactions for Detection of Survivin mRNA in Malignant SW480 Cells

Movable toehold for leakless self-assembly circuits

Nonenzymatic self-assembly circuit utilizing hairpin substrates has been developed to be a powerful tool for information transduction, amplification and computation. However, the sensitivity, stability and application of this circuit are impeded by the presence of leakage which refers to undesired triggering in the absence of input. Herein, we proposed a movable toehold principle to suppress leakage and accelerate the catalytic reaction through removing partial hairpin toehold responsible for the leakage and transferring it to the catalyst. With movable toehold, catalytic hairpin assembly (called mtCHA) exhibited an excellent signal-to-background ratio of over 100, high robustness and improved specificity. In more complex circuit, including proximity recognition, signal amplification of small molecules (such as ATP), logic network, autocatalysis circuit and two-layer cascade circuit, mtCHA also demonstrated satisfactory performance. Our findings suggest that mtCHA holds great potential for broader applications, and the approach of repurposing harmful fragments into beneficial candidates can provide valuable insights for other chemical systems.

DNA Aptamer Beacon Probe (ABP) for Monitoring of Adenosine Triphosphate Level in SW480 Cancer Cells Treated with Glycolysis Inhibitor 2-Deoxyglucose

Early cancer screening enables timely detection of carcinogenesis, and aids in prompt clinical intervention. Herein, we report on the development of a simple, sensitive, and rapid fluorometric assay based on the aptamer probe (aptamer beacon probe, ABP) for monitoring the energy-demand biomarker adenosine triphosphate (ATP), an essential energy source that is released into the tumor microenvironment. Its level plays a significant role in risk assessment of malignancies. The operation of the ABP for ATP was examined using solutions of ATP and other nucleotides (UTP, GTP, CTP), followed by monitoring of ATP production in SW480 cancer cells. Then, the effect of a glycolysis inhibitor, 2-deoxyglucose (2-DG), on SW480 cells was investigated. The stability of predominant ABP conformations in the temperature range of 23-91 °C and the effects of temperature on ABP interactions with ATP, UTP, GTP, and CTP were evaluated based on quenching efficiencies (QE) and Stern-Volmer constants (K_SV). The optimized temperature for best selectivity of ABP toward ATP was 40 °C (K_SV = 1093 M^-1, QE = 42%). We have found that the inhibition of glycolysis in SW480 cancer cells by 2-deoxyglucose resulted in lowering of ATP production by 31.7%. Therefore, monitoring and modulation of ATP concentration may aid in future cancer treatment.

Simultaneous Imaging and Visualizing the Association of Survivin mRNA and Telomerase in Living Cells by Using a Dual-Color Encoded DNA Nanomachine

Simultaneous imaging and especially visualizing the association of survivin mRNA and telomerase in living cells are of great value for the diagnosis and prognosis of cancer because their co-expression facilitates the development of cancer and identifies patients at high risk of tumor-related death. The challenge is to develop methods that enable visualizing the association of multiplex targets and avoid the distorted signals due to the different delivery efficiency of probes. Herein, we engineered a DNA triangular prism nanomachine (DTPN) for simultaneous multicolor imaging of survivin mRNA and telomerase and visualizing their association in living cells. Two recognizing probes targeted survivin mRNA and telomerase, and the reporter probe was assembled on the DTP in equal amounts, ensuring the same delivery efficiency of the probes to the living cells. The results showed that this DTPN could quantify intracellular survivin mRNA expression and telomerase activity. Moreover, it also enabled us to visualize the effect of the down-regulation of one target on the expression of another target under different drug stimulations. The results implied that our DTPN provided a promising platform for cancer diagnosis, prognosis, drug screening, and related biological research.

The Impact of Molecular Biology in the Seeding, Treatment Choices and Follow-Up of Colorectal Cancer Liver Metastases-A Narrative Review

There is a clear association between the molecular profile of colorectal cancer liver metastases (CRCLM) and the degree to which aggressive progression of the disease impacts patient survival. However, much of our knowledge of the molecular behaviour of colorectal cancer cells comes from experimental studies with, as yet, limited application in clinical practice. In this article, we review the current advances in the understanding of the molecular behaviour of CRCLM and present possible future therapeutic applications. This review focuses on three important steps in CRCLM development, progression and treatment: (1) the dissemination of malignant cells from primary tumours and the seeding to metastatic sites; (2) the response to modern regimens of chemotherapy; and (3) the possibility of predicting early progression and recurrence patterns by molecular analysis in liquid biopsy.

Precise Detection on Cell-Cell Fusion by a Facile Molecular Beacon-Based Method

Cell-cell fusion studies provide an experimental platform for evaluating disease progression and investigating cell infection. However, to realize sensitive and quantitative detection on cell-cell fusion is still a challenge. Herein, we report a facile molecular beacon (MB)-based method for precise detection on cell-cell fusion. By transfection of the spike protein (S protein) and enhanced green fluorescent protein (EGFP) in HEK 293 cells, the virus-mimicking fusogenic effector cells 293-S-EGFP cells were constructed to interact with target cells. Before mixing the effector cells with the target cells, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression in 293-S-EGFP cells was silenced, and the MB for GAPDH mRNA detection was delivered into the GAPDH silenced 293-S-EGFP cells. Once cell-cell fusion occurred, MB migrated from the GAPDH silenced effector cells to the target cells and hybridized with GAPDH mRNA in the target cells to induce fluorescence emission. The cell-cell fusion can be easily visualized and quantitated by fluorescence microscopy and flow cytometry. The fluorescence intensity is strongly dependent on the number of fused target cells. This MB-based method can easily identify the differences in the cell fusions for various target cells with different angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) expression levels, resulting in dramatically different fluorescence intensities in fused target cells. Our study provides a convenient and efficient quantitative detection approach to study cell-cell fusion.

DNA-enabled fluorescent-based nanosensors monitoring tumor-related RNA toward advanced cancer diagnosis: A review

As a burgeoning non-invasive indicator for reproducible cancer diagnosis, tumor-related biomarkers have a wide range of applications in early cancer screening, efficacy monitoring, and prognosis predicting. Accurate and efficient biomarker determination, therefore, is of great importance to prevent cancer progression at an early stage, thus reducing the disease burden on the entire population, and facilitating advanced therapies for cancer. During the last few years, various DNA structure-based fluorescent probes have established a versatile platform for biological measurements, due to their inherent biocompatibility, excellent capacity to recognize nucleic and non-nucleic acid targets, obvious accessibility to synthesis as well as chemical modification, and the ease of interfacing with signal amplification protocols. After decades of research, DNA fluorescent probe technology for detecting tumor-related mRNAs has gradually grown to maturity, especially the advent of fluorescent nanoprobes has taken the process to a new level. Here, a systematic introduction to recent trends and advances focusing on various nanomaterials-related DNA fluorescent probes and the physicochemical properties of various involved nanomaterials (such as AuNP, GO, MnO2, SiO2, AuNR, etc.) are also presented in detail. Further, the strengths and weaknesses of existing probes were described and their progress in the detection of tumor-related mRNAs was illustrated. Also, the salient challenges were discussed later, with a few potential solutions.

Facile Label-Free Electrochemical DNA Biosensor for Detection of Osteosarcoma-Related Survivin Gene

A sensitive and selective electrochemical deoxyribonucleic acid (DNA) biosensor was developed for the determination of a osteosarcoma-related survivin gene by using celestine blue (CB) as a label-free hybridization indicator. The proposed strategy adopted a facile and low-cost working electrode with no need for other substances for electrode or DNA functionalization. The interaction mode between CB and DNA was studied by electrochemical and spectroscopic approaches, illustrating that the possible mode was intercalation with a binding number of 2 and a binding constant β of 10^12.87. Moreover, the label-free electrochemical DNA biosensor exhibited a good linear relationship toward the target gene in a range from 1.00 nM to 50.00 nM with a detection limit as low as 0.046 nM using 3σ estimating system. This facile and low-cost electrochemical method realized the rapid detection and accurate quantification of the target sequence in complicated serum samples, endowing its promising potential in the diagnosis and monitoring of genetic diseases.

A novel binding-induced DNAzyme motor triggered by survivin mRNA

The accurate and sensitive detection of survivin mRNA is of great significance for cancer diagnosis and treatment. However, limited by the low-abundance mRNA in live cells, most strategies of survivin mRNA detection that were one-to-one signal-triggered model (one target triggered one signal) were inapplicable in practice. Here, we reported a binding-induced DNAzyme motor triggered by the survivin mRNA, which was a one-to-more signal-triggered model (one target triggered more signals), amplifying the detection signal and enhancing the sensitivity. The nanomotor is constructed by assembling several DNAzyme motor strands silenced by the blocker strands, and dozens of FAM-labeled substrate strands on a single gold nanoparticle (AuNP), forming three-dimensional DNA tracks. Through building the survivin mRNA bridge between the blocker and the DNAzyme motor strand, the binding-induced DNA nanomotor could be triggered by survivin mRNA. The operation of the DNAzyme motor was self-powered. And each walking step of the DNAzyme motor was fueled by DNAzyme-catalyzed substrate cleavage, along with the cleavage of the fluorescent molecule, resulting in autonomous and progressive walking along the AuNP-based tracks, and the fluorescence increase. The DNAzyme motor exhibited excellent sensitivity and remarkable specificity for survivin mRNA, providing the potential for cell image.

Methods for Collection of Extracellular Vesicles and Their Content RNA as Liquid Biopsy for Lung Cancer Detection: Application of Differential Centrifugation and Annexin A5 Coated Beads

Extracellular vesicles (EVs) contain abundant extracellular RNA (exRNA), which can be a valuable source of liquid biopsy. However, as various RNA species exist in different types of EVs, lack of detailed characterization of these RNA species and efficient collection methods limits the clinical application of exRNA. In the present study, we measured two mRNAs, CK19 and PCTK1; one lncRNA, MALAT1; and two miRNAs, miR21 and miR155, in different EV fractions separated by differential centrifugation or captured by magnetic beads coated with annexin A5 (ANX beads). The results showed that in a cultured medium, the majority of mRNA and lncRNA exist in larger EVs, whereas miRNA exist in both large and small EVs from the differential centrifugation fractions. All these RNA species exist in ANX beads captured EVs. We then used ANX beads to capture EVs in plasma samples from non-small-cell lung cancer patients and age-matched healthy volunteers. We found that the ANX bead capturing could efficiently improve RNA detection from human plasma, compared with direct extraction of RNA from plasma. Using ANX-bead capturing and reverse transcription and quantitative PCR, we detected significantly higher levels of CK19 mRNA, MALAT1 lncRNA, and miR155 miRNA in the plasma of lung cancer patients. These facts suggested the collection methods strongly affect the results of exRNA measurement from EVs, and that ANX beads can be a useful tool for detecting exRNA from plasma samples in clinical application.

Using an ATR-FTIR Technique to Detect Pathogens in Patients with Urinary Tract Infections: A Pilot Study

Urinary tract infections (UTIs) are a leading hospital-acquired infection. Although timely detection of causative pathogens of UTIs is important, rapid and accurate measures assisting UTI diagnosis and bacterial determination are poorly developed. By reading infrared spectra of urine samples, Fourier-transform infrared spectroscopy (FTIR) may help detect urine compounds, but its role in UTI diagnosis remains uncertain. In this pilot study, we proposed a characterization method in attenuated total reflection (ATR)-FTIR spectra to evaluate urine samples and assessed the correlation between ATR-FTIR patterns, UTI diagnosis, and causative pathogens. We enrolled patients with a catheter-associated UTI in a subacute-care unit and non-UTI controls (total n = 18), and used urine culture to confirm the causative pathogens of the UTIs. In the ATR-FTIR analysis, the spectral variation between the UTI group and non-UTI, as well as that between various pathogens, was found in a range of 1800-900 cm^-1, referring to the presence of specific constituents of the bacterial cell wall. The results indicated that the relative ratios between different area zones of vibration, as well as multivariate analysis, can be used as a clue to discriminate between UTI and non-UTI, as well as different causative pathogens of UTIs. This warrants a further large-scale study to validate the findings of this pilot research.

Upconversion Luminescence-Initiated and GSH-Responsive Self-Driven DNA Motor for Automatic Operation in Living Cells and In Vivo

In light of the worthy design flexibility and the good signal amplification capacity, the recently developed DNA motor (especially the DNA walker)-based fluorescent biosensors can offer an admirable choice for realizing bioimaging. However, this attractive biosensing strategy not only has the disadvantage of uncontrollable initiation but also usually demands the supplement of exogenous driving forces. To handle the above obstacles, some rewarding solutions are proposed here. First, on the surface of an 808 nm near-infrared light-excited low-heat upconversion nanoparticle, a special ultraviolet upconversion luminescence-initiated three-dimensional (3D) walking behavior is performed by embedding a photocleavage linker into the sensing elements, and such light-controlled target recognition can perfectly overcome the pre-triggering of the biosensor during the biological delivery to significantly boost the sensing precision. After that, a peculiar self-driven walking pattern is constructed by employing MnO₂ nanosheets as an additional nanovector to physically absorb the sensing frame, for which the reduction of the widespread glutathione in the biological medium can bring about sufficient self-supplied Mn²⁺ to guarantee the walking efficiency. By selecting an underlying next-generation broad-spectrum cancer biomarker (survivin messenger RNA) as the model target, we obtain that the newly formed autonomous 3D DNA motor shows a commendable sensitivity (where the limit of detection is down to 0.51 pM) and even an outstanding specificity for distinguishing single-base mismatching. Beyond this sound assay performance, our sensing approach is capable of working as a powerful imaging platform for accurately operating in various living specimens such as cells and bodies, showing a favorable diagnostic ability for cancer care.

Dynamic tracking of p21 mRNA in living cells by sticky-flares for the visual evaluation of the tumor treatment effect

Monitoring the expression level of the intracellular tumor suppressor gene p21 mRNA is essential to reveal the progress and prognosis of a tumor. Methods widely reported for the detection of p21 mRNA are the real-time polymerase chain reaction and Northern blot. However, these methods only detect mRNA in vitro and cannot realize the in situ monitoring of the p21 mRNA expression level in living cells. Additionally, the sensor for the real-time tracking and monitoring of the p21 mRNA location without the help of a transfection reagent in living cells is still limited. Herein, a novel sticky-flare was constructed for the dynamic monitoring of the temporal and spatial variations of p21 mRNA in living cells. The nanoprobe consists of AuNP, a recognition sequence modified with Cy5, and a thiol-modified DNA sequence. The thiol oligonucleotide strand could act partially complementary to the Cy5-modified oligonucleotide strand to form a double-stranded DNA linked to AuNP, resulting in the fluorescence quenching of Cy5 due to the energy transfer from Cy5 to the gold sphere. In the presence of p21 mRNA, the Cy5-modified recognition nucleic acid specifically bound to p21 mRNA to form a more stable double chain and escaped from the gold sphere, leading to the recovery of red fluorescence. Our method is better than other methods in its ability to quantify the spatial distribution and expression level of p21 mRNA in living cells and discriminate various tumor cell lines with different p21 mRNA expression levels by the naked eye. Particularly, the sticky-flare probe used in this assay could allow the visual evaluation of the tumor treatment effect and the determination of the tumor progression stage by enabling monitoring of the relative expression level of p21 mRNA in tumor cells after cisplatin treatment. The method reported here is accurate, reliable and needs no auxiliary tools (transfection reagent), and thereby provides a promising route for the prognostic evaluation and drug development of cancer treatment in the future.

Ultrasensitive fluorescent detection of telomerase activity based on tetrahedral DNA nanostructures as carriers for DNA-templated silver nanoclusters

Precise evaluation of telomerase activity is essential for the clinical diagnosis of early tumors. Herein, we have ingeniously designed a tetrahedral DNA nanostructure, with hairpin-shaped DNA probes rich in cytosine bases at four vertices for telomerase detection. The DNA-templated silver nanoclusters can be formed after the addition of Ag. Then the introduction of telomerase adds the single-strand TTAGGG extension, which can "turn on" the fluorescence of silver nanoclusters quickly by the proximity of the resulting guanine-rich sequences to silver nanoclusters and realize accurate detection of telomerase activity. In this study, integration of high stability tetrahedral DNA nanostructure and fluorescence signal amplification of four DNA-templated silver nanoclusters offers the advantage of high sensitivity, with a low detection limit of 1 cell. More than that, this method is low-cost, facile, and feasible for practical clinical applications.

Quantitative and Selective DNA Detection with Portable Personal Glucose Meter Using Loop-Based DNA Competitive Hybridization Strategy

A portable, quantitative, and selective DNA detection biosensor, based on a loop-based DNA competitive hybridization assay and a personal glucose meter (PGM), is an advanced strategy for one-step target DNA recognition and signal reporter generation. In the presence of target DNA, the invertase-DNA conjugates are released due to the competitive binding of target DNA and collected with the help of a magnet subsequently. The released invertase-DNA could catalyze the hydrolysis of sucrose into glucose with millions of turnovers which is target concentration dependent. In addition, the sensor exhibits excellent anti-interference ability, having almost no effect on the detection performance in serum. The biosensor shown here is easier to operate owning its great potential in point of care testing in environments with limited resources and skilled personnel for rapid and sensitive detection of specific DNA sequence in real biological samples.

Label-free and reagentless electrochemical genosensor based on graphene acid for meat adulteration detection

With the increased demand for beef in emerging markets, the development of quality-control diagnostics that are fast, cheap and easy to handle is essential. Especially where beef must be free from pork residues, due to religious, cultural or allergic reasons, the availability of such diagnostic tools is crucial. In this work, we report a label-free impedimetric genosensor for the sensitive detection of pork residues in meat, by leveraging the biosensing capabilities of graphene acid - a densely and selectively functionalized graphene derivative. A single stranded DNA probe, specific for the pork mitochondrial genome, was immobilized onto carbon screen-printed electrodes modified with graphene acid. It was demonstrated that graphene acid improved the charge transport properties of the electrode, following a simple and rapid electrode modification and detection protocol. Using non-faradaic electrochemical impedance spectroscopy, which does not require any electrochemical indicators or redox pairs, the detection of pork residues in beef was achieved in less than 45 min (including sample preparation), with a limit of detection of 9% w/w pork content in beef samples. Importantly, the sample did not need to be purified or amplified, and the biosensor retained its performance properties unchanged for at least 4 weeks. This set of features places the present pork DNA sensor among the most attractive for further development and commercialization. Furthermore, it paves the way for the development of sensitive and selective point-of-need sensing devices for label-free, fast, simple and reliable monitoring of meat purity.

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.

Snowflake-like DNA crystals templated Cu clusters as a fluorescent turn-on probe for sensing actin

Herein, we synthesized snowflake-like DNA crystals (SDC) via hybridization chain reaction and used it for the first time in the synthesis of copper nanoclusters with enhanced fluorescence. Atomic force microscopy (AFM) and laser confocal microscopy characterization confirmed that SDC/CuNCs are self-assembled successfully on SDC. Aggregation induced emission allows SDC/CuNCs to exhibit better stability and stronger emission intensity. Thus, we developed the "turn-on" label-free fluorescence detection method of actin based on SDC/CuNCs which offer simplicity, low cost, good selectivity, and high sensitivity. The detection limit was determined to be 0.0124 μg mL^-1, which was an order of magnitude lower than that of reported fluorescent methods (0.12 μg mL^-1). Compared with previous method, the linear range is also much wider. We also performed standard recovery experiments in actual samples for evaluating the practicality of this strategy and proved that the capability of the proposed approach for the determination of actin is feasible and the interference from complex biological samples is negligible. These results indicate that SDC/CuNCs are expected to play a more important role in the field of biosensors.

Retinoids as Chemo-Preventive and Molecular-Targeted Anti-Cancer Therapies

Retinoic acid (RA) agents possess anti-tumor activity through their ability to induce cellular differentiation. However, retinoids have not yet been translated into effective systemic treatments for most solid tumors. RA signaling is mediated by the following two nuclear retinoic receptor subtypes: the retinoic acid receptor (RAR) and the retinoic X receptor (RXR), and their isoforms. The identification of mutations in retinoid receptors and other RA signaling pathway genes in human cancers offers opportunities for target discovery, drug design, and personalized medicine for distinct molecular retinoid subtypes. For example, chromosomal translocation involving RARA occurs in acute promyelocytic leukemia (APL), and all-trans retinoic acid (ATRA) is a highly effective and even curative therapeutic for APL patients. Thus, retinoid-based target discovery presents an important line of attack toward designing new, more effective strategies for treating other cancer types. Here, we review retinoid signaling, provide an update on retinoid agents and the current clinical research on retinoids in cancer, and discuss how the retinoid pathway genotype affects the ability of retinoid agents to inhibit the growth of colorectal cancer (CRC) cells. We also deliberate on why retinoid agents have not shown clinical efficacy against solid tumors and discuss alternative strategies that could overcome the lack of efficacy.

Photo-gated and self-powered three-dimensional DNA motors with boosted biostability for exceptionally precise and efficient tracing of intracellular survivin mRNA

Benefiting from the outstanding signal amplification effect and the admirable construction flexibility, the currently proposed DNA motors (particularly DNA walkers) based biosensing concepts have provided a forceful fluorescence imaging tool for intracellular detection. Even so, this promising sensing means is not only subject to poor controllability and prone to produce false signals but also requires exogenous powering forces owing to the common employment of DNAzyme. In response to these challenges, we are herein motivated to present some meaningful solving strategies. For one thing, the surfaces of gold nanoparticles are conducted with a photo-gated walking behavior by introducing a photocleave mode, under which the light-switchable DNA walkers are capable of being selectively activated via an external ultraviolet source to faultlessly prevent the sensing frame from being pre-initiated during cellular uptake and intracellular delivery. For another, the intracellular biothiols are consumed by MnO₂ nanosheets to effectively avoid the competitions to Au-S bonds to eliminate potential false outputs and also self-supply sufficient cofactors (Mn²⁺) to actualize a self-powered operation pattern as well as facilitate the endocytosis process. Following these breakthroughs, a favorable analysis performance towards a model tumor biomarker (survivin mRNA) is endowed with the newly raised biosensor, whose sensitivity is low to pM level with a sound specificity for identifying single base mismatching. Moreover, the significantly improved autonomous three-dimensional DNA walkers can be used to determine and dynamically trace the targets in live cancer cells with an exceptional precise and efficient manner, commendably impelling the sensing ability of DNA motors in biological specimens.

A DNA-functionalized biomass nanoprobe for the targeted photodynamic therapy of tumor and ratiometric fluorescence imaging-based visual cancer cell identification/antitumor drug screening

Survivin is widely expressed in tumor tissue, in which the in situ ratiometric fluorescence imaging of intracellular survivin mRNA can provide accurate information for the diagnosis and treatment of cancers, as well as the screening of antitumor drugs. However, the development of a nanoprobe that can be used simultaneously in the diagnosis and treatment of tumors and the screening of antitumor drugs remains a challenge. In an effort to address these requirements, a multifunctional biomass nanoprobe was developed for the photodynamic therapy (PDT) of tumors as well as cancer cell identification and antitumor drug screening based on the ratiometric fluorescence imaging of intracellular survivin mRNA. This nanoprobe was assembled from near-infrared (NIR) biomass quantum dots (BQDs), single-stranded DNA and NIR dye (dylight680) labeled single-stranded DNA. The BQDs contain a large number of chlorophyll molecules, meaning that they can produce a large amount of singlet oxygen under NIR light irradiation, thus realizing the PDT of a tumor. However, the specific binding of the nanoprobe to intracellular survivin mRNA causes the release of dylight680 and reduces the fluorescence resonance energy transfer (FRET) efficiency between the BQDs and dylight680 in the probe, thereby achieving the ratiometric fluorescence imaging of survivin mRNA. Therefore, the prepared nanoprobe can not only be used in the diagnosis of cancers, but also in the targeted PDT of tumors.

DNA-assisted synthesis of Ortho-NanoDimer with sub-nanoscale controllable gap for SERS application

Nanostructure with precisely controllable narrow gap width remains a great challenge, especially at the sub-nanoscale level. Here, a versatile strategy named as DNA-assisted synthesis of ortho-nanodimer (DaSON) is proposed to fabricate Ag (Au) nanodimers with a uniform gap width from nanometers to angstroms. In such a strategy, two nanoparticles are constrained by the equilibrium state of the DNA hybridization and electrostatic repulsion to form zipper-like ortho-nanostructures with an extremely uniform gap whose width can be finely adjusted at nanoscale or sub-nanoscale by changing the DNA sequence and the surface charge of nanoparticles. The inherent strong electromagnetic coupling in the uniform sub-nanometer gap can generates an unparalleled SERS enhancement together with an extraordinary reproducibility. Compared with conventional DNA-based nano-gap fabrication strategy, the DaSON strategy enhances the SERS intensity for more than two orders of magnitude with a detection limit of 100 aM for DNA, and significantly improves the reproducibility in both labeled and label-free SERS sensing applications. Moreover, the DaSON strategy holds wide applicability for arbitrary kinds of DNA-modifiable nanoparticles. Therefore, we believe that the DaSON strategy provides an innovative method for the synthesis of nanostructures with controllable nanogaps and has a promising future in multiple fields including nanotechnology, catalysis and photonics.

MXene Surface on Multiple Junction Triangles for Determining Osteosarcoma Cancer Biomarker by Dielectrode Microgap Sensor

Background

In recent years, nanomaterials have justified their dissemination for biosensor application towards the sensitive and selective detections of clinical biomarkers at the lower levels. MXene is a two-dimensional layered transition metal, attractive for biosensing due to its chemical, physical and electrical properties along with the biocompatibility.

Materials and Methods

This work was focused on diagnosing osteosarcoma (OS), a common bone cancer, on MXene-modified multiple junction triangles by dielectrode sensing. Survivin protein gene is highly correlated with OS, identified on this sensing surface. Capture DNA was immobilized on MXene by using 3-glycidoxypropyltrimethoxysilane as an amine linker and duplexed by the target DNA sequence.

Results

The limitation and sensitivity of detection were found as 1 fM with the acceptable regression co-efficient value (y=1.0037⨰ + 0.525; R²=0.978) and the current enhancement was noted when increasing the target DNA concentrations. Moreover, the control sequences of single- and triple-mismatched and noncomplementary to the target DNA sequences failed to hybridize on the capture DNA, confirming the specificity. In addition, different batches were prepared with capture probe immobilized sensing surfaces and proved the efficient reproducibility.

Conclusion

This microgap device with Mxene-modified multiple junction triangles dielectrode surface is beneficial to quantify the survivin gene at its lower level and diagnosing OS complication levels.

High-Fidelity Determination and Tracing of Small Extracellular Vesicle Cargoes

Direct tracing of small extracellular vesicle (sEV) cargoes holds unprecedented importance for elucidating the mechanisms involved in intercellular communication. However, high-fidelity determination of sEVs' molecular cargoes in situ has yet to be achieved due to the difficulty in transporting molecular probes into intact sEVs. Herein, a fLuorescent Intracellular-Guided Hairpin-Tetrahedron (fLIGHT) nanoprobe is described for direct visualization of sEV microRNAs in situ. Integrating the advantages of nondestructive sEV penetration via DNA origami and single-nucleotide discrimination as well as wash-free fluorescence readout using a hairpin probe, the proposed approach enables high-fidelity fluorescence visualization of sEVs' microRNA without RNA extraction or leakage, demonstrating the potential of on-site tracing of sEV cargoes. This strategy opens an avenue to establishing universal molecular detection and labeling platforms that can facilitate both sEV-derived fundamental biological studies and molecular diagnostics.

Smart Nanocarriers for the Delivery of Nucleic Acid-Based Therapeutics: A Comprehensive Review

Nucleic acid-based therapies are promising therapeutics for the treatment of several systemic disorders, and they offer an exciting opportunity to address emerging biological challenges. The scope of nucleic acid-based therapeutics in the treatment of multiple disease states including cancers has been widened by recent progress in Ribonucleic acids (RNA) biology. However, cascades of systemic and intracellular barriers, including rapid degradation, renal clearance, and poor cellular uptake, hinder the clinical effectiveness of nucleic acid-based therapies. These barriers can be circumvented by utilizing advanced smart nanocarriers that efficiently deliver and release the encapsulated nucleic acids into the target tissues. This review describes the current status of clinical trials on nucleic acid-based therapeutics and highlights representative examples that provide an overview on the current and emerging trends in nucleic acid-based therapies. A better understanding of the design of advanced nanocarriers is essential to promote the translation of therapeutic nucleic acids into a clinical reality.

Electrochemical biosensor for rapid detection of bacteria based on facile synthesis of silver wire across electrodes

The early detection of bacteria is of critical importance in addressing serious public health problems. Here, an electrochemical biosensor for rapid detection of bacteria based on facile synthesis of silver wire across electrodes was constructed. High-variable region of 16S rRNA of bacteria was used as biomarker. Polymerase-free synthesis of silver wire was introduced into electrochemical signal transduction to improve the sensitivity of electrochemical detection. The construction biosensor of proposed method is as follows: Metastable hairpin probe H₁ was modified on electrode surface, biomarker can open the stem-loop structure of H₁ and activates HCR. The alternate opening of the stem-loop structure of H₁ and H₂-AuNPs finally results in the formation of long double-stranded DNA-RNA (HCR products) -AuNPs. The formed AuNPs modified HCR products was blown in one direction using N₂ to across the electrode gap. Using this HCR products as template, the silver wire was formed between the electrodes by silver deposition, and resulted in sharp change in electrical parameters of electrode. As the proof-of-concept work, multichannel series piezoelectric quartz crystal (MSPQC) was utilized as detector. The detection of Staphylococcus aureus in the concentration range from 50 to 10⁷ CFU/mL within 100 min was achieved. The detection limit was 50 CFU/mL. Escherichia coli, Salmonella enteritidis, Listeria innocua, Pseudomonas aeruginosa and Streptococcus pneumoniae did not interfere the detection results. This newly proposed electrochemical biosensor is simple, rapid and exhibit high signal-to-noise ratio, it has great potential for being applied in food safety monitoring and clinical diagnosis.

RNA Sequencing in Comparison to Immunohistochemistry for Measuring Cancer Biomarkers in Breast Cancer and Lung Cancer Specimens

RNA sequencing is considered the gold standard for high-throughput profiling of gene expression at the transcriptional level. Its increasing importance in cancer research and molecular diagnostics is reflected in the growing number of its mentions in scientific literature and clinical trial reports. However, the use of different reagents and protocols for RNA sequencing often produces incompatible results. Recently, we published the Oncobox Atlas of RNA sequencing profiles for normal human tissues obtained from healthy donors killed in road accidents. This is a database of molecular profiles obtained using uniform protocol and reagents settings that can be broadly used in biomedicine for data normalization in pathology, including cancer. Here, we publish new original 39 breast cancer (BC) and 19 lung cancer (LC) RNA sequencing profiles obtained for formalin-fixed paraffin-embedded (FFPE) tissue samples, fully compatible with the Oncobox Atlas. We performed the first correlation study of RNA sequencing and immunohistochemistry-measured expression profiles for the clinically actionable biomarker genes in FFPE cancer tissue samples. We demonstrated high (Spearman's rho 0.65-0.798) and statistically significant (p < 0.00004) correlations between the RNA sequencing (Oncobox protocol) and immunohistochemical measurements for HER2/ERBB2, ER/ESR1 and PGR genes in BC, and for PDL1 gene in LC; AUC: 0.963 for HER2, 0.921 for ESR1, 0.912 for PGR, and 0.922 for PDL1. To our knowledge, this is the first validation that total RNA sequencing of archived FFPE materials provides a reliable estimation of marker protein levels. These results show that in the future, RNA sequencing can complement immunohistochemistry for reliable measurements of the expression biomarkers in FFPE cancer samples.

A tumour mRNA-triggered nanoassembly for enhanced fluorescence imaging-guided photodynamic therapy

A multifunctional theranostic nanoplatform, which integrates diagnostic and therapeutic functions in a single nanosystem, holds great promise for guiding disease treatment and improving the corresponding therapy efficacy. We report the development of a novel g-C3N4 nanosheet-based theranostic nanoassembly for both enhanced imaging of cancer-relevant mRNA in living cells and imaging-guided on-demand photodynamic therapy (PDT) for tumors. The nanoassembly was constructed by using highly fluorescent and water-dispersible g-C3N4 nanosheets which act as nanocarriers, enabling efficient and self-tracking transfection of the DNA hairpin probes. The presence of intracellular mRNA will initiate the DNA hairpin probes, ultimately resulting in an amplified fluorescence signal via hybridization and displacement with mRNA. Moreover, enhanced fluorescence imaging-guided precise PDT for tumors in living cells was also demonstrated, allowing the selective ablation of tumors without any obvious side effects. Therefore, the developed theranostic approach can provide a promising platform for low-abundance biomarker discovery and early treatment of related diseases.

Ryanodine receptor-targeting small molecule fluorescent probes enables non-isotopic labeling and efficient drug screening for green insecticides

Ryanodine receptors (RyRs) are calcium release channels located on endoplasmic reticulum (ER) membrane, which play important role in excitation-contraction coupling in muscular response. Flubendiamide represents a novel chemical family of green insecticides which selectively activate invertebrate RyR by interacting with the receptor distinct from the ryanodine binding site and has almost no effect on mammalian ryanodine receptors. Traditional methods to screen RyR modulators involve either radio-labeled RyR substrates or calcium signal-based indirect approaches. However, there is lack of RyR-directed non-isotope molecular tools for RyR agonists/antagonists screening and bioimaging. Here we developed a series of fluorescent probes based on the pharmacophore of flubendiamide with the aims to elucidate the mechanism of diamide insecticides and screen novel RyR-targeting insecticides. These probes revealed the specific RyR staining and in vivo RyR targeting properties in diamondback moth RyR transfected Sf9 cells (Sf9-RyR) and RyR enriched insect tissues. The designed fluorescent probes could induce an effective calcium release from ER membrane of Sf9-RyR cells and also showed competitive RyR binding effect with flubendiamide in cell-based fluorometric assay. Having the non-isotope RyR recognition probes will not only accelerate the screening process of new green agrochemicals but also enables deciphering molecular mechanisms of the high selectivity and the drug resistance associated with the diamides.

Rolling Circle Amplification-Based Polyvalent Molecular Beacon Probe-Assisted Signal Amplification Strategies for Sensitive Detection of B16 Cells

We developed a simple and sensitive signal amplification method for the detection of B16 cells based on the combination of rolling circle amplification (RCA) and molecular beacons (MBs). A long-chain structure of DNA synthesized by RCA was used to turn on aptamer-based MBs. Because of the multiple complementary repeat units, the RCA scaffold hybridized tens or hundreds of MBs to form polyvalent aptamer probes. The unfold ability and the fluorescence intensity of MBs were both improved by RCA, as compared to short single chains. The cell experiment results demonstrated that RCA-based polyvalent MBs were significantly more effective than monovalent MBs in targeting B16 cells and signal sensitivity because of their multivalent effects. The establishment of this strategy would provide a powerful platform for early clinical diagnostics of cancer cells.

Magnetic Nanoparticles for Nanomedicine

The field of nanomedicine has recently emerged as a product of the expansion of a range of nanotechnologies into biomedical science, pharmacology and clinical practice. Due to the unique properties of nanoparticles and the related nanostructures, their applications to medical diagnostics, imaging, controlled drug and gene delivery, monitoring of therapeutic outcomes, and aiding in medical interventions, provide a new perspective for challenging problems in such demanding issues as those involved in the treatment of cancer or debilitating neurological diseases. In this review, we evaluate the role and contributions that the applications of magnetic nanoparticles (MNPs) have made to various aspects of nanomedicine, including the newest magnetic particle imaging (MPI) technology allowing for outstanding spatial and temporal resolution that enables targeted contrast enhancement and real-time assistance during medical interventions. We also evaluate the applications of MNPs to the development of targeted drug delivery systems with magnetic field guidance/focusing and controlled drug release that mitigate chemotherapeutic drugs’ side effects and damage to healthy cells. These systems enable tackling of multiple drug resistance which develops in cancer cells during chemotherapeutic treatment. Furthermore, the progress in development of ROS- and heat-generating magnetic nanocarriers and magneto-mechanical cancer cell destruction, induced by an external magnetic field, is also discussed. The crucial roles of MNPs in the development of biosensors and microfluidic paper array devices (µPADs) for the detection of cancer biomarkers and circulating tumor cells (CTCs) are also assessed. Future challenges concerning the role and contributions of MNPs to the progress in nanomedicine have been outlined.

Monitoring of dynamic ATP level changes by oligomycin-modulated ATP synthase inhibition in SW480 cancer cells using fluorescent "On-Off" switching DNA aptamer

Adenosine triphosphate (ATP) is the main energy source in cells and an important biomolecule participating in cellular reactions in living organisms. Since the ATP level changes dynamically reflecting the development of a debilitating disease or carcinogenesis, we have focused in this work on monitoring of the oligomycin (OMC)-modulated ATP synthase inhibition using a fluorescent-switching DNA aptamer designed for the detection of ATP (Apt(ATP)), as the model for studies of dynamic ATP level variation. The behavior of the ATP aptamer has been characterized using fluorescence spectroscopy. The Intramolecular fluorescence resonance energy transfer (iFRET) operates in the proposed aptamer from the FAM dye moiety to guanines of the aptamer G-quadruplex when the target ATP is present and binds to the aptamer changing its conformation. The iFRET process enables the detection of ATP down to the limit of detection, LOD = 17 μM, without resorting to any extra chemi-amplification schemes. The selectivity coefficients for relevant interferent triphosphates (UTP, GTP, and CTP) are low for the same concentration as that of ATP. We have demonstrated an efficient transfection of intact cells and OMC-treated SW480 colon cancer cells with Apt(ATP), using microscopic imaging, iFRET measurements, and cell viability testing with MTT method. The applicability of the switching DNA aptamer for the analysis of real samples, obtained by lysis of SW480 cells, was also tested. The proposed Apt(ATP) may be considered as a viable candidate for utilization in measurements of dynamic ATP level modulation in cells in different stages of cancer development and testing of new drugs in pharmacological studies.

Toward early cancer detection: Focus on biosensing systems and biosensors for an anti-apoptotic protein survivin and survivin mRNA

The development of biosensors for cancer biomarkers has recently been expanding rapidly, offering promising biomedical applications of these sensors as highly sensitive, selective, and inexpensive bioanalytical tools that can provide alternative methodology to that afforded by the advanced hyphenated-instrumental techniques. In this review, we focus particularly on the detection of a member of the inhibitor of apoptosis proteins (IAP) family, protein survivin (Sur), a ubiquitous re-organizer of the cell life cycle with the ability to inhibit the apoptosis and induce an enhanced proliferation leading to the unimpeded cancer growth and metastasis. Herein, we critically evaluate the progress in the development of novel biosensing systems and biosensors for the detection of two survivin (Sur) biomarkers: the Sur protein and its messenger RNA (Sur mRNA), including immunosensors, electrochemical piezo- and impedance-sensors, electrochemi-luminescence biosensors, genosensors based on oligonucleotide molecular beacons (MBs) with fluorescent or electrochemical transduction, as well as the microfluidic and related analytical platforms based on solution chemistry. The in-situ applications of survivin biomarkers' detection technologies to equip nanocarriers of the controlled drug delivery systems with MB-based fluorescence imaging capability, apoptosis control, and mitigation of the acquired drug resistance are also presented and critically evaluated. Finally, we turn the attention to the application of biosensors for the analysis of Sur biomarkers in exosomes and circulating tumor cells for a non-invasive liquid biopsy. The prospect of a widespread screening for early cancers, based on inexpensive point-of-care testing using biosensors and multiplex biosensor arrays, as a means of reducing the high cancer fatality rate, is discussed.

Accurate detection of intracellular microRNAs using functional Mo2C quantum dots nanoprobe

A functionalized Mo₂C quantum dots nanoprobe was developed for accurate detection of intracellular mature microRNAs.

MHY440, a Novel Topoisomerase Ι Inhibitor, Induces Cell Cycle Arrest and Apoptosis via a ROS-Dependent DNA Damage Signaling Pathway in AGS Human Gastric Cancer Cells

We investigated the antitumor activity and action mechanism of MHY440 in AGS human gastric cancer cells. MHY440 inhibited topoisomerase (Topo) Ι activity and was associated with a DNA damage response signaling pathway. It exhibited a stronger anti-proliferative effect on AGS cells relative to Hs27 human foreskin fibroblast cells, and this effect was both time- and concentration-dependent. MHY440 also increased cell arrest in the G2/M phase by decreasing cyclin B1, Cdc2, and Cdc25c, and upregulating p53 and p73. MHY440 induced AGS cell apoptosis through the upregulation of Fas-L, Fas, and Bax as well as the proteolysis of BH3 interacting-domain death agonist and poly(ADP-ribose) polymerase. It also contributed to the loss of mitochondrial membrane potential. The apoptotic cell death induced by MHY440 was inhibited by pretreatment with Z-VAD-FMK, a pan-caspase inhibitor, indicating that apoptosis was caspase-dependent. Moreover, the apoptotic effect of MHY440 was reactive oxygen species (ROS)-dependent, as evidenced by the inhibition of MHY440-induced PARP cleavage and ROS generation via N-acetylcysteine-induced ROS scavenging. Taken together, MHY440 showed anticancer effects by inhibiting Topo I, regulating the cell cycle, inducing apoptosis through caspase activation, and generating ROS, suggesting that MHY440 has considerable potential as a therapeutic agent for human gastric cancer.

Classical Triplex Molecular Beacons for MicroRNA-21 and Vascular Endothelial Growth Factor Detection

Triplex molecular beacons (tMBs) possess great potential in biological sensing because of the pH responsiveness and controllability of binding strength. Here, we systematically investigate and rationally design a classical tMB for convenient detection of microRNA-21, a well-known biomarker of cardio-cerebrovascular diseases. In the tMB, we employ the complementary sequence of miR-21 as the loop and the sequences of protonated cytosine-guanine-cytosine (C-G•C+) and thymine-adenine-thymine (T-A•T) as the triplex stem, in which both the Watson-Crick and Hoogsteen base-pairing control the binding strength in cooperation. It is demonstrated for the first time that the presence of miR-21 would only break the Hoogsteen base-pairing in the stem and hybridize with the tMB to form the rigid heterozygous hybrid duplex structure. These would hinder the fluorescence resonance energy transfer (FRET) between the fluorophore (FAM) and quencher (BHQ1) labeled at the ends of the oligonucleotide, and the fluorescence recovery degree of FAM can be used as the standard to quantitate the miR-21. More significantly, the excellent adjustability and sensitivity of our tMBs have been confirmed by constructing the corresponding duplex molecular beacon (dMB) for comparison. The fluorophore FAM in the tMB could be replaced by the fluorescent DNA/silver nanoclusters, which exhibits the universal applicability of energy donor and receptor selection for tMB. Furthermore, our proposed tMB could also be developed as an aptasensor for the detection of vascular endothelial growth factor (VEGF) by only introducing the complementary sequence of its aptamer into the tMB. This work is of great significance for the systematic study of tMBs for the detection of biomarkers such as nucleic acids and proteins.

Optical Biosensing System for the Detection of Survivin mRNA in Colorectal Cancer Cells Using a Graphene Oxide Carrier-Bound Oligonucleotide Molecular Beacon

The anti-apoptotic protein survivin is one of the most promising cancer biomarkers owing to its high expression in human cancers and rare occurrence in normal adult tissues. In this work, we have investigated the role of supramolecular interactions between a graphene oxide (GO) nanosheet nanocarrier and a survivin molecular beacon (SurMB), functionalized by attaching fluorophore Joe and quencher Dabcyl (SurMB-Joe). Molecular dynamics simulations revealed hydrogen bonding of Joe moiety and Dabcyl to GO carriers that considerably increase the SurMB-GO bonding strength. This was confirmed in experimental work by the reduced fluorescence background in the OFF state, thereby increasing the useful analytical signal range for mRNA detection. A new mechanism of hairpin–hairpin interaction of GO@SurMB with target oligonucleotides has been proposed. A low limit of detection, LOD = 16 nM (S/N = 3), has been achieved for complementary tDNA using GO@SurMB-Joe nanocarriers. We have demonstrated an efficient internalization of SurMB-Joe-loaded GO nanocarriers in malignant SW480 cells. The proposed tunability of the bonding strength in the attached motifs for MBs immobilized on nanocarriers, via structural modifications, should be useful in gene delivery systems to enhance the efficacy of gene retention, cell transfection and genomic material survivability in the cellular environment.