Engineering of catalytic hairpin-rigidified Y-shaped DNA-functionalized nanomachine to rapidly detect mRNA.

The catalytic hairpin-rigidified Y-shaped DNA through layer-by-layer assembly has been fixed on the surface of copper sulfide nanoparticles for the detection of survivin mRNA. The distance between the CHA probes fixed on the Y-shaped DNA is significantly shortened. The results show that the fluorescence of this nanomachine reached the maximum value in 50 min (excitation wavelength at 488 nm and emission wavelength 526 nm), and its reaction rate is more than 5-fold faster than that of the free-CHA control system. In addition, the nanomachine showed high sensitivity (LOD of 3.5 pM) and high specificity for the survivin mRNA detection. Given its fast response time and excellent detection performance, we envision that the catalytic hairpin-rigidified Y-shaped DNA-functionalized nanomachine will offer potential applications in disease diagnostics and clinical applications.

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.

Simultaneous Imaging of Endogenous Survivin mRNA and On-Demand Drug Release in Live Cells by Using a Mesoporous Silica Nanoquencher.

The design of multifunctional drug delivery systems capable of simultaneous target detection, imaging, and therapeutics in live mammalian cells is critical for biomedical research. In this study, by using mesoporous silica nanoparticles (MSNs) chemically modified with a small-molecule dark quencher, followed by sequential drug encapsulation, MSN capping with a dye-labeled antisense oligonucleotide, and bioorthogonal surface modification with cell-penetrating poly(disulfide)s, the authors have successfully developed the first mesoporous silica nanoquencher (qMSN), characterized by high drug-loading and endocytosis-independent cell uptake, which is able to quantitatively image endogenous survivin mRNA and release the loaded drug in a manner that depends on the survivin expression level in tumor cells. The authors further show that this novel drug delivery system may be used to minimize potential cytotoxicity encountered by many existing small-molecule drugs in cancer therapy.

Survivin mRNA-circulating tumor cells are associated with prostate cancer metastasis.

Detection of circulating tumor cells (CTCs) has been made to develop reliable assays for early diagnosis of various cancers. Overexpression of survivin in cancer cells is strongly associated with tumor progression. Although upregulation of survivin is observed in various tumors, its expression profile in the peripheral blood of prostate cancer (PCa) patients has not yet been investigated. In this study, we validated the application of survivin as the tumor marker to detect CTC and assessed its utility for diagnosis of PCa distant metastasis. Immunohistochemistry and quantitative real-time PCR (QRT-PCR) were performed to confirm the levels of surviving expression in PCa tissues. In addition, CTC values in 3 mL of peripheral blood from PCa patients, benign prostate hyperplasia (BPH) patients, and normal controls were also measured by the survivin-targeted PCR. Our results showed that surviving was overexpressed in PCa tissues. The median levels of blood surviving mRNA of PCa patients, BPH patients, and normal controls were 5.67 (range from 0 to 12.46), 2.24 (range from 0 to 6.55), and 1.85 (range from 0 to 3.82), respectively. The levels of survivin are positively associated with PCa distant metastasis. Our results concluded that quantitation of CTCs through survivin-PCR could be a promising marker for diagnosis of PCa metastasis.

Programming the dynamic range of nanobiosensors with engineering poly-adenine-mediated spherical nucleic acid.

Spherical nucleic acid (SNA) conjugates consisting of gold cores functionalized with a densely packed DNA shells are of great significance in the field of medical detection and intracellular imaging. Especially, poly adenine (polyA)-mediated SNAs can improve the controllability and reproducibility of DNA assembly on the nanointerface, showing the tunable hybridization ability. However, due to the physics of single-site binding, the biosensor based on SNA usually exhibits a dynamic range spanning a fixed 81-fold change in target concentration, which limits its application in disease monitoring. To address this problem, we report a tri-block DNA-based approach to assemble SNA for nucleic acid detection based on structure-switching mechanism with programmable dynamic range. The tri-block DNA is a FAM-labeled stem-loop structure, which contains three blocks: polyA block as an anchoring block for tunable surface density, stem block with different GC base pair content for varying the structure stability, and the fixed loop block for target recognition. We find that varying the polyA block, the reaction temperature, and the GC base pair, SNA shows different target binding affinity and detection limit but with normally 81-fold dynamic range. We can extend the dynamic range to 1000-fold by using the combination of two SNAs with different affinity, and narrow the dynamic range to 5-fold by sequestration mechanism. Furthermore, the tunable SNA enables sensitive detection of mRNA in cells. Given its tunable dynamic range, such nanobiosensor based on SNA offers new possibility for various biomedical and clinical applications.

Detection of long mRNA sequences by a Y-shaped DNA probe with three target-binding segments.

Tumor-related mRNA detection is significant and interesting. The current mRNA detection method has the challenge of quantifying long mRNA sequences. Herein, a Y-shaped DNA probe with three target-binding segments was developed to detect tumor-related mRNA. This Y-shaped DNA probe (Y-probe) was assembled by six single DNA strands. Among these DNA strands, two DNA strands contained the split G-quadruplex sequence, and two DNA strands were modified with a pair of fluorophore and quencher, which were used to produce the detectable signal. In the presence of a long target mRNA sequence, target mRNA was hybridized with the three target-binding segments of the Y-probe, resulting in the increased fluorescence of G-quadruplex specific dye Thioflavin T and the decreased fluorescence of fluorophore, which could achieve the ratio detection of target mRNA. The Y-probe exhibited a low detection limit of 17.53 nM. Moreover, this probe showed high accuracy due to the benefits of three target-binding segments.

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.

Broad-Spectrum Polymeric Nanoquencher as an Efficient Fluorescence Sensing Platform for Biomolecular Detection.

Colloidal inorganic nanostructures (metal, carbon, and silica) have been widely used as "nanoquenchers" for construction of nanosensors; however, inherent drawbacks such as insufficient fluorescence quenching efficiency, false positive signals, and uncertain long-term cytotoxicity have limited their further utility. Herein, by taking advantages of polymeric nanoparticles (PNPs) in terms of high loading capacity, facile surface modification chemistry, and good biocompatibility, we report a broad-spectrum (400-750 nm) polymeric fluorescence-quenching platform for sensor fabrication. Our newly developed polymeric nanoquenchers (qPNPs) were constructed by concurrently encapsulating various alkylated black-hole quenchers into nanoparticles made of poly(methyl methacrylate-co-methacrylic acid) and were found to have an excellent fluorescence quenching effect (>400-fold) on common fluorophores (FAM, TMR, and Cy5) together with high stability under physiological conditions. As a proof of concept, the feasibility of these qPNPs for fluorescence sensing was validated by successful construction of two nanosensors (FAMDEVD@qPNP and Cy5SurC@qPNP), which could be used as promising nanosensors for live-cell imaging of the apoptosis-related protease caspase-3 and cancer-related survivin mRNA, respectively. As expected, in the FAM channel, the FAMDEVD@qPNP showed fast and selective fluorescence responses toward caspase-3 in buffers and could be used to image the activation of drug-induced endogenous caspase-3. In the Cy5 channel, the Cy5SurC@qPNP could be used to distinguish normal cells (MCF10A) from cancer cells (HeLa) by quantitatively detecting the endogenous survivin mRNA level. It could be further used to monitor changes in the endogenous survivin mRNA expression levels in drug-treated HeLa cells. Altogether, by virtue of their high quencher loading and broad-spectrum quenching efficiency and good signal-to-background ratio, these qPNPs might be particularly attractive alternatives to other conventional nanoquenchers for the construction of more complex biosensors in the future.

mRNA-Activated Multifunctional DNAzyme Nanotweezer for Intracellular mRNA Sensing and Gene Therapy.

Deoxyribozyme (DNAzyme) is regarded as a promising gene therapy drug. However, poor cellular uptake efficacy and low biological stability limit the utilization of DNAzyme in gene therapy. Here, we report a well-known programmable DNAzyme-based nanotweezer (DZNT) that provides a new strategy for the detection of TK1 mRNA and survivin mRNA-targeted gene silencing therapy. At the end of the DZNT arm, there are two functionalized single-stranded DNA and each consists of two parts: the segment complementary to TK1 mRNA and the split-DNAzyme segment. The hybridization with intracellular TK1 mRNA enables the imaging of TK1 mRNA. Meanwhile, the hybridization draws the split-DNAzyme close to each other and activates DNAzyme to cleave the survivin mRNA to realize gene silencing therapy. The results demonstrate that the DZNT nanocarrier has excellent cell penetration, good biocompatibility, and noncytotoxicity. DZNT can image intracellular biomolecule TK1 mRNA with a high contrast. Furthermore, the split-DNAzyme can efficiently cleave the survivin mRNA with the aid of TK1 mRNA commonly present in cancer cells, accordingly can selectively kill cancer cells, and has no harm to normal cells. Taken together, the multifunctional programmable DZNT provides a promising platform for the early diagnosis of tumors and gene therapy.

Enzyme-free electrochemical biosensor based on amplification of proximity-dependent surface hybridization chain reaction for ultrasensitive mRNA detection.

The ability to recognize mRNA with high efficiency in cells would greatly facilitate the elucidation of mRNA-mediated cellular cascades and their disease associations. However, most traditional electrochemical strategies targeting nucleotides are always confronted with cumbersome interface operation and washing procedures, as well as the high cost of labeling and the strict reaction conditions of tool enzymes, limiting their potential applications. To address these issues, herein we reported, for the first time, a simple label-free, isothermal, non-enzymatic, and ultrasensitive homogeneous electrochemical biosensor based on autonomous proximity-dependent surface hybridization chain reaction (HCR), for sensitive signal amplification and highly specific detection of target survivin mRNA with a detection limit of 3 fM. The target triggers hybridization chain reaction and mRNA-fueled surface hybridization of ferrocene-tagged metastable DNA hairpin probes on proximity-dependent surface hybridization, resulting in the formation of multiple long-range duplex DNA chains which are immobilized onto the gold electrodes with a substantially stable ferrocene-mediated redox current. Thus, a significant electrochemical signal increase is observed dependent on the concentration of the target RNA, with a very low detection limit. Mo-reover, this molecular biosensor also exhibits excellent specificity to distinguish even single base mismatched, with strong reliability. The developed biosensor provides a novel promising tool for ultra-sensitive and selective detection, and it has great potential to be applied in mRNA-related biochemical research and clinical cancer diagnostics in more detail.

Diagnostic accuracy of urinary survivin mRNA expression detected by RT-PCR compared with urine cytology in the detection of bladder cancer: A meta-analysis of diagnostic test accuracy in head-to-head studies.

Survivin is a promising marker for the diagnosis of bladder cancer. The accuracy and clinical value of urinary survivin mRNA expression were compared with urine cytology, which is the standard diagnostic method for bladder cancer. Scientific databases, including PubMed, Web of Science, Cochrane Library and China National Knowledge Infrastructure, were searched in order to find studies that examined urinary survivin mRNA expression and urine cytology in the diagnosis of bladder cancer. Quality assessment was performed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool in Revman 5.3 and data analysis was conducted using Stata/MP. The I2 statistic was used to evaluate heterogeneity and Deeks' funnel plot was generated to assess the possibility of publication bias. A total of 15 studies that evaluated a total of 1,624 patients were included in the present meta-analysis. The pooled sensitivity and specificity values for the detection of urinary survivin mRNA expression in the diagnosis of bladder cancer were 0.86 [95% confidence interval (CI), 0.81-0.90] and 0.95 (95% CI, 0.93-0.96), respectively. Regarding urine cytology, the pooled sensitivity and specificity values were 0.42 (95% CI, 0.36-0.48) and 1.00 (95% CI, 0.98-1.00), respectively. Furthermore, the differences in pooled sensitivity were statistically significant in the diagnosis of grade 1 and 2 bladder tumors. Summary receiver operating characteristic curve values for urinary survivin mRNA expression and urine cytology were 0.95 (95% CI, 0.93-0.97) and 0.86 (95% CI, 0.83-0.89), respectively. Urinary survivin mRNA expression was also more accurate compared with other diagnostic indicators, including positive likelihood ratios, negative likelihood ratios, diagnostic odds ratios and Youden's index. Compared with traditional urine cytology, urinary survivin mRNA detection using reverse transcription-PCR was identified to be more effective in the diagnosis of early bladder cancer.

WITHDRAWN: Performance of survivin mRNA as a biomarker for breast cancer among Vietnamese women.

Ahead of Print article withdrawn by publisher.

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.

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.