M-CDC: Magnetic pull-down-assisted colorimetric method based on the CRISPR/Cas12a system.

The construction of a rapid, simple, and specific nucleic acid detection platform is of great significance to the control of the large-scale spread of infectious diseases. We have recently established a magnetic pull-down-assisted colorimetric method based on the CRISPR/Cas12a system (termed M-CDC), which effectively integrates the advantages of CRISPR/Cas12a, magnetic beads-based separation, and AuNP bioprobe to provide a simple and specific biosensing platform for nucleic acid assay. The M-CDC method is compatible with point-of-care testing and enables the detection of nucleic acid samples in less than an hour without relying on expensive and complex instruments. In this paper, step-by-step instructions for M-CDC assay, including recombinase polymerase amplification (RPA)/reverse transcription-polymerase chain reaction (RT-RPA) of DNA or RNA, Cas12a-mediated target recognition and cleavage, and subsequent magnetic beads-mediated colorimetric readouts are provided. In addition, the protocol for the expression and purification of Lachnospiraceae bacterium-Cas12a (LbCas12a) protein, the design and synthesis of high-efficient crRNA, and the preparation of AuNP bioprobe are also offered.

Glycerol Additive Boosts 100-fold Sensitivity Enhancement for One-Pot RPA-CRISPR/Cas12a Assay.

CRISPR/Cas12, a highly efficient and specific nucleic acid recognition system, has been broadly employed to detect amplified DNA products. However, most reported methods adopt a two-step detection mode that needs a liquid transfer step, thus complicating the detection procedure and posing a risk of aerosol contamination. A one-pot detection method can obviate these problems, but it suffers from poor detection efficiency due to the loss of amplification templates elicited by CRISPR/Cas12 cleavage. In this study, we discovered that a glycerol additive dramatically promoted the detection efficiency of the one-pot recombinase polymerase amplification (RPA)-CRISPR/Cas12a method. Compared with the glycerol-free version, its sensitivity was nearly 100-fold higher and was close to that of the canonical two-step method. Further investigation displayed that the enhanced detection efficiency was attributed to the phase separation of the RPA and CRISPR/Cas12a system during the initial phase of the RPA reaction caused by the glycerol viscosity. This highly efficient one-pot method has been triumphantly harnessed for the detection of African swine fever virus (ASFV) and SARS-CoV-2, achieving naked-eye readout through a smartphone-equipped device. The currently developed glycerol-enhanced one-pot RPA-CRISPR/Cas12a method can be an advantageous point-of-care nucleic acid detection platform on account of its simplicity, high sensitivity, and universality.

Droplet Cas12a Assay Enables DNA Quantification from Unamplified Samples at the Single-Molecule Level.

DNA quantification is important for biomedical research, but the routinely used techniques rely on nucleic acid amplification which have inherent issues like cross-contamination risk and quantification bias. Here, we report a CRISPR-Cas12a-based molecular diagnostic technique for amplification-free and absolute quantification of DNA at the single-molecule level. To achieve this, we first screened out the optimal reaction parameters for high-efficient Cas12a assay, yielding over 50-fold improvement in sensitivity compared with the reported Cas12a assays. We further leveraged the microdroplet-enabled confinement effect to perform an ultralocalized droplet Cas12a assay, obtaining excellent specificity and single-molecule sensitivity. Moreover, we demonstrated its versatility and quantification capability by direct counting of diverse virus's DNAs (African swine fever virus, Epstein-Barr virus, and Hepatitis B virus) from clinical serum samples with a wide range of viral titers. Given the flexible programmability of crRNA, we envision this amplification-free technique as a versatile and quantitative platform for molecular diagnosis.

A CRISPR/Cas9 eraser strategy for contamination-free PCR end-point detection.

Polymerase chain reaction (PCR), a central technology for molecular diagnostics, is highly sensitive but susceptible to the risk of false positives caused by aerosol contamination, especially when an end-point detection mode is applied. Here, we proposed a solution by designing a clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 eraser strategy for eliminating potential contamination amplification. The CRISPR/Cas9 engineered eraser is firstly adopted into artpcr reverse-transcription PCR (RT-PCR) system to achieve contamination-free RNA detection. Subsequently, we extended this CRISPR/Cas9 eraser to the PCR system. We engineered conventional PCR primers to enable the amplified products to contain an implanted NGG (protospacer adjacent motif, PAM) site, which is used as a code for specific CRISPR/Cas9 recognition. Pre-incubation of Cas9/sgRNA with PCR mix leads to a selective cleavage of contamination amplicons, thus only the template DNA is amplified. The developed CRISPR/Cas9 eraser, adopted by both RT-PCR and PCR systems, showed high-fidelity detection of SARS-CoV-2 and African swine fever virus with a convenient strip test.

Simultaneous Dual-Gene Diagnosis of SARS-CoV-2 Based on CRISPR/Cas9-Mediated Lateral Flow Assay.

Few methods for the detection of SARS-CoV-2 currently have the capability to simultaneously detect two genes in a single test, which is a key measure to improve detection accuracy, as adopted by the gold standard RT-qPCR method. Developed here is a CRISPR/Cas9-mediated triple-line lateral flow assay (TL-LFA) combined with multiplex reverse transcription-recombinase polymerase amplification (RT-RPA) for rapid and simultaneous dual-gene detection of SARS-CoV-2 in a single strip test. This assay is characterized by the detection of envelope (E) and open reading frame 1ab (Orf1ab) genes from cell-cultured SARS-CoV-2 and SARS-CoV-2 viral RNA standards, showing a sensitivity of 100 RNA copies per reaction (25 µL). Furthermore, dual-gene analysis of 64 nasopharyngeal swab samples showed 100 % negative predictive agreement and 97.14 % positive predictive agreement. This platform will provide a more accurate and convenient pathway for diagnosis of COVID-19 or other infectious diseases in low-resource regions.

Postoperative encapsulated hemoperitoneum in a patient with gastric stromal tumor treated by exposed endoscopic full-thickness resection: A case report.

BACKGROUND: Gastric stromal tumors, originating from mesenchymal tissues, are one of the most common tumors of the digestive tract. For stromal tumors originating from the muscularis propria, compared with conventional endoscopic submucosal dissection (ESD), endoscopic full-thickness resection (EFTR) can remove deep lesions and digestive tract wall tumors completely. However, this technique has major limitations such as perforation, postoperative bleeding, and post-polypectomy syndrome. Herein, we report a case of postoperative serous surface bleeding which formed an encapsulated hemoperitoneum in a patient with gastric stromal tumor that was treated with exposed EFTR. Feasible treatment options to address this complication are described. CASE SUMMARY: A 47-year-old male patient had a hemispherical protrusion found during gastric endoscopic ultrasonography, located at the upper gastric curvature adjacent to the stomach fundus, with a smooth surface mucosa and poor mobility. The lesion was 19.3 mm × 16.1 mm in size and originated from the fourth ultrasound layer. Computed tomography (CT) revealed no significant evidence of lymph node enlargement or distant metastasis. Using conventional ESD technology for mucosal pre-resection, exposed EFTR was performed to resect the intact tumor in order to achieve a definitive histopathological diagnosis. Based on its morphology and immunohistochemical expression of CD117 and DOG-1, the lesion was proven to be consistent with a gastric stromal tumor. Six days after exposed EFTR, CT showed a large amount of encapsulated fluid and gas accumulation around the stomach. In addition, gastroscopy suggested intracavitary bleeding and abdominal puncture drainage indicated serosal bleeding. Based on these findings, the patient was diagnosed with serosal bleeding resulting in encapsulated abdominal hemorrhage after exposed EFTR for a gastric stromal tumor. The patient received combined treatments, such as hemostasis under gastroscopy, gastrointestinal decompression, and abdominal drainage. All examinations were normal within six months of follow-up. CONCLUSION: This patient developed serous surface bleeding in the gastric cavity following exposed EFTR. Serosal bleeding resulting in an encapsulated hemoperitoneum is rare in clinical practice. The combined treatment may replace certain surgical techniques.

Graphene oxide-deposited microfiber: a new photothermal device for various microbubble generation.

This study makes a claim of utilizing the photothermal effect of graphene oxide nanosheets (GONs) to effectively produce various microbubbles in an optical microfiber system at infrared optical communications band. A low power continuous-wave light at wavelength of 1527-1566 nm was launched into the microfiber to form GONs-deposition which acted as a linear heat source for creating various microbubbles. Both thermal convection flow and optical gradient force were responsible for the driving force to assemble GONs onto the microfiber. This simple optical fiber system can be used for assembling other micro/nanoscale particles and biomolecules, which has prospective applications in sensing, microfluidics, virus detection, and other biochip techniques.

Exploiting the orthogonal CRISPR-Cas12a/Cas13a trans-cleavage for dual-gene virus detection using a handheld device.

Although CRISPR-Cas12a and CRISPR-Cas13a systems work individually effective on gene detection, their multiplex detection capability is limited due to the lack of specific probe cleavage mechanism. Herein we present a high-efficient dual-gene diagnostic technique based on the orthogonal DNA/RNA collateral cleavage mechanism of Cas12a/Cas13a system. In this design, dual-gene amplified products from the multiplex recombinase polymerase amplification (RPA) were simultaneously detected by Cas12a and Cas13a assay in a single tube. The resulting orthogonal DNA/RNA collateral cleavage can specifically illuminate two spectral differentiated DNA and RNA probes, respectively. By integrating with the smartphone-based fluorescence readout, a portable detection platform is achieved. As a proof-of-concept, reliable dual-gene detection of SARS-CoV-2 and African Swine fever virus (ASFV) were demonstrated, exhibiting 100% sensitivity and specificity for clinical samples analysis (32 swab specimens for SARS-CoV-2 and 35 ASFV suspected swine blood samples). This developed portable dual-gene detection platform can provide accurate point-of-care screening of infectious diseases in resources-limited settings.

Fast microwave heating-based one-step synthesis of DNA and RNA modified gold nanoparticles.

DNA/RNA-gold nanoparticle (DNA/RNA-AuNP) nanoprobes have been widely employed for nanobiotechnology applications. Here, we discover that both thiolated and non-thiolated DNA/RNA can be efficiently attached to AuNPs to achieve high-stable spherical nucleic acid (SNA) within minutes under a domestic microwave (MW)-assisted heating-dry circumstance. Further studies show that for non-thiolated DNA/RNA the conjugation is poly (T/U) tag dependent. Spectroscopy, test strip hybridization, and loading counting experiments indicate that low-affinity poly (T/U) tag mediates the formation of a standing-up conformation, which is distributed in the outer layer of SNA structure. In further application studies, CRISPR/Cas9-sgRNA (136 bp), SARS-CoV-2 RNA fragment (1278 bp), and rolling circle amplification (RCA) DNA products (over 1000 bp) can be successfully attached on AuNPs, which overcomes the routine methods in long-chain nucleic acid-AuNP conjugation, exhibiting great promise in biosensing and nucleic acids delivery applications. Current heating-dry strategy has improved traditional DNA/RNA-AuNP conjugation methods in simplicity, rapidity, cost, and universality.

A CRISPR-driven colorimetric code platform for highly accurate telomerase activity assay.

Telomeric repeat amplification protocol (TRAP) has been the most widely used method for assessing the telomerase activity from cells and tissues. However, cell lysates, body fluid samples, or tumor tissue samples often contain high concentrations of protein or other complex matrices, which are usually inhibiting the TRAP response, thus leading to false-negative results. Internal control (IC) involved TRAP enables reliable telomerase activity assay but requires time consuming and laborious electrophoretic separation to visualize telomeric repeat DNA and internal control products from TRAP reaction, severely limiting its application in clinical diagnosis. Herein, a colorimetric code system based on programmable CRISPR-Cas12a technology and gold nano-particles (AuNPs) probe has been developed to analyse telomeric repeat DNA and internal control in TRAP products, enabling the rapid detection of telomerase activity and identification of false-negatives with naked-eye. We transform the detection results into three typical colorimetric codes-positive (P), negative (N) and false-negative (FN), making the judgement of detection results more convenient and user-friendly. The platform has also been applied in accurate detection of clinical liver cancer specimens for telomerase activity with a detection sensitivity of 93.75% and a specificity of 93.75% based on Youden index analysis. As a proof of concept, we further demonstrated the feasibility of Cas9-mediated triple-line lateral flow assay (TL-LFA), which enabled the detection of telomeric repeat DNA and internal control on a single triple-line test strip, achieving convenient and accurate telomerase activity assay.

Magnetic bead and nanoparticle based electrochemiluminescence amplification assay for direct and sensitive measuring of telomerase activity.

The broad-spectrum expression of telomerase in most malignancies makes it a promising target for a cancer diagnostic and prognostic tool. Conventional polymerase chain reaction (PCR)-based telomerase activity assay is highly sensitive but susceptible to amplification-related errors. Here, we present a novel approach to telomerase activity detection. The detection of telomerase activity is accomplished by the hybridization of electrochemiluminescence (ECL) nanoprobes to telomerase reaction products, subsequent capture by magnetic beads, and in situ measurement of the light signal from ECL nanoprobes. The ECL intensity directly reflects the quantity of telomerase reaction products, thus telomerase activity. The high sensitivity afforded by the current magnetic bead and nanoparticle based ECL detection platform allows measuring of telomerase activity from as little as 500 cultured cancer cells in crude cell extracts without the PCR amplification of telomerase reaction products. In addition, a comparative study of the ECL nanoprobe and linear telomere antisense ECL probe was executed. By the employment of the ECL nanoprobe, a gain of about 100-fold elevation of sensitivity was determined. The method described here is ideal for telomerase activity analysis due to its reliability and high sensitivity.

Cucurbit[6]uril modified CdTe quantum dots fluorescent probe and its selective analysis of p-nitroaniline in environmental samples.

An efficient fluorescent probe based on cucurbit[6]uril modified CdTe quantum dots (CB[6]@QDs) was prepared. This novel probe showed significant and selective fluorescence quenching and complexation capacity to p-nitroaniline, its interaction mechanism was studied by both experimental and theoretical methods. Furthermore, a fluorescent method was developed for the determination of p-nitroaniline in different environmental samples. The fluorescence intensity of CB[6]@QDs showed a good linearity response to p-nitroaniline in the concentration range of 2.5 × 10-7-3.0 × 10-6 mol/L with a correlation coefficient (R2) of 0.9976, the limit of detection (LOD) was 6 × 10-8 mol/L and the limit of quantification (LOQ) was 2 × 10-7 mol/L. Moreover, about 0-1.5 × 10-6 mol/L p-nitroaniline were determined in environmental samples, the recoveries were in the range of 88-109% with the relative standard deviations (n = 3) of 1.2-4.5%. Compared with previous fluorescent methods, the present method shortened and simplified the sample pretreatment as well as enhanced the sensitivity and selectivity of analytical method. No further sample pretreatment procedure is needed and the LOD of present method was one order of magnitude less than previous fluorescent methods, showed it is a simple, selective and sensitive method.

PCR-free quantitative detection of genetically modified organism from raw materials. An electrochemiluminescence-based bio bar code method.

A bio bar code assay based on oligonucleotide-modified gold nanoparticles (Au-NPs) provides a PCR-free method for quantitative detection of nucleic acid targets. However, the current bio bar code assay requires lengthy experimental procedures including the preparation and release of bar code DNA probes from the target-nanoparticle complex and immobilization and hybridization of the probes for quantification. Herein, we report a novel PCR-free electrochemiluminescence (ECL)-based bio bar code assay for the quantitative detection of genetically modified organism (GMO) from raw materials. It consists of tris-(2,2'-bipyridyl) ruthenium (TBR)-labeled bar code DNA, nucleic acid hybridization using Au-NPs and biotin-labeled probes, and selective capture of the hybridization complex by streptavidin-coated paramagnetic beads. The detection of target DNA is realized by direct measurement of ECL emission of TBR. It can quantitatively detect target nucleic acids with high speed and sensitivity. This method can be used to quantitatively detect GMO fragments from real GMO products.

Low-power laser irradiation inhibiting Abeta25-35-induced PC12 cell apoptosis via PKC activation.

Apoptosis is a contributing pathophysiological mechanism of Alzheimer's disease (AD). Recently, low-power laser irradiation (LPLI) has been applied to moderate AD, but the underlying mechanism remains unknown. In this study, the techniques of fluorescence resonance energy transfer (FRET) and real-time quantitative RT-PCR were used to investigate the anti-apoptotic mechanism of LPLI. Rat pheochromocytoma (PC12) cells were treated with amyloid beta 25-35 (Abeta(25-35)) for induction of apoptosis before LPLI treatment. The cell viability assays and morphological examinations show that low fluence of LPLI (0.156 J/cm(2)-0.624 J/cm(2)) could inhibit the cells apoptosis. An increase of PKC activation was dynamically monitored in the cells treated with PMA (specific activator of PKC), LPLI only or Abeta(25-35) followed by 5 min LPLI treatment, respectively. However, the effect of LPLI activating PKC could be inhibited by Go 6983 (specific inhibitor of PKC). Similar results were obtained by using Western blot analysis. Furthermore, LPLI involved an increase in mRNA of the cell survival member bcl-xl and a decrease in the up-regulation of cell death member bax mRNA caused by Abeta(25-35). Further data show that low fluence of LPLI could reverse the increased level of bax/bcl-xl mRNA ratio caused by Abeta(25-35) treatment. In addition, Go 6983 could inhibit the decreased level of bax/bcl-xl mRNA ratio. Taken together, these data clearly indicate that LPLI inhibited Abeta(25-35)-induced PC12 cell apoptosis via PKC-mediated regulation of bax/bcl-xl mRNA ratio.

Ultrasensitive electrochemiluminescence detection of Staphylococcus aureus via enzyme-free branched DNA signal amplification probe.

As a main cause of foodborne diseases, pathogenic bacteria have threatened the health and well-being of human communities. There is a need of fastness, accuracy and sensitivity in the method of detecting pathogenic bacteria. Classical signal amplification assays usually employ enzymes as biocatalysts to generate amplified signals, but the strict experimental conditions and complicated instruments restrict their application. In this work, we demonstrated an enzyme-free branched DNA (bDNA)-based signal amplification electrochemiluminescence (ECL) assay for ultrasensitive detection of pathogenic bacteria. Firstly, the capture probes and the amplification probes group were carefully designed by our research group. The detecting ECL signal of Staphylococcus aureus (S. aureus) was amplified by bDNA technique through the layer-by-layer signal amplification. The sensitivity was greatly improved by the use of multiple Ru(bpy)32+ (TBR)-labeled ECL probes. Secondly, the whole process of the detection was carried out in the absence of enzyme, without the need to control the reaction conditions strictly. Thirdly, the designed amplification probes group could be used for the analysis of other pathogenic bacteria, virus, tumor markers, biomarkers, etc. For the detection of S. aureus, the limit of detection (LOD) of the method was 2 pM for standard DNA, with the linear range from 20 pM to 100 nM. Last but not least, the LOD of the S. aureus asymmetric PCR products was 5 pM, with the linear range from 10 pM to 50 nM. The sensitivity was 1-2 orders in magnitude higher than that of the common detection assays.

Point-of-care testing for streptomycin based on aptamer recognizing and digital image colorimetry by smartphone.

The rapid detection of antibiotic residual in everyday life is very important for food safety. In order to realize the on-site and visual detection of antibiotic, a POCT method was established by using digital image colorimetry based on smartphone. Streptomycin was taken as the analyte model of antibiotics, streptomycin aptamer preferentially recognized analyte, and the excess aptamer hybridized with the complementary DNA to form the dsDNA. SYBR Green I combined with the dsDNA and then emitted obvious green fluorescence, thus the fluorescence intensity decreased with the increasing of streptomycin concentration. Then a smartphone-based device was constructed as the fluorescence readout. The smartphone camera acquired the images of the fluorescence derived from the samples, and the Touch Color APP installed in smartphone read out the RGB values of the images. There was a linear relationship between the G values and the streptomycin concentrations in the range of 0.1-100µM. The detection limit was 94nM, which was lower than the maximum residue limit defined by World Health Organization. The POCT method was applied for determining streptomycin in chicken and milk samples with recoveries in 94.1-110%. This method had the advantages of good selectivity, simple operation and on-site visualization.

Constitutive androstane receptor activation promotes bilirubin clearance in a murine model of alcoholic liver disease.

Increased plasma levels of bilirubin have been reported in rat models and patients with alcoholic liver disease (ALD). The constitutive androstane receptor (CAR) is a known xenobiotic receptor, which induces the detoxification and transport of bilirubin. In the present study, the bilirubin transport regulatory mechanisms, and the role of CAR activation in hepatic and extrahepatic bilirubin clearance were investigated in a murine model of ALD. The mice were fed a Lieber-DeCarli ethanol diet or an isocaloric control diet for 4 weeks, followed by the administration of CAR agonists, 1,4-bis-[2­(3,5-dichlorpyridyloxy)]benzene (TCPOBOP) and phenobarbital (PB), and their vehicles to examine the effect of the pharmacological activation of CAR on serum levels of bilirubin and on the bilirubin clearance pathway in ALD by serological survey, western blotting and reverse transcription­quantitative polymerase chain reaction. The results showed that chronic ethanol ingestion impaired the nuclear translocation of CAR, which was accompanied by elevated serum levels of bilirubin, suppression of the expression of hepatic and renal organic anion transporting polypeptide (OATP) 1A1 and hepatic multidrug resistance­associated protein 2 (MRP2), and induction of the expression of UDP-glucuronosyltransferase (UGT) 1A1. The activation of CAR by TCPOBOP and PB resulted in downregulation of the serum levels of bilirubin followed by selective upregulation of the expression levels of OATP1A1, OATP1A4, UGT1A1 and MRP2 in ALD. These results revealed the bilirubin transport regulatory mechanisms and highlighted the importance of CAR in modulating the bilirubin clearance pathway in the ALD mouse model.

Effects of IkappaBalpha and its mutants on NF-kappaB and p53 signaling pathways.

AIM: To study the effects of IkappaBalpha and its mutants (IkappaBalphaM, IkappaBalpha243N, IkappaBalphaM244C) on NF-kappaB, p53 and their downstream target genes. The relationship of NF-kappaB, p53, and IkappaBalpha was further discussed. METHODS: pECFP-IkappaBalpha, pECFP-IkappaBalphaM (amino acides 1-317, Ser32, 36A), pECFP-IkappaBalpha243N (amino acides 1-243), pECFP-IkappaBalpha244C (amino acides 244-317), pEYFP-p65 and pp53-DsRed were constructed and transfected to ASTC-alpha-1 cells. Cells were transfected with pECFP-C1 as a control. 30 h after the transfection, location patterns of NF-kappaB, p53 and IkappaBalpha (IkappaBalphaM, IkappaBalpha243N, IkappaBalpha244C) were observed by a laser scanning microscope (LSM510/ConfoCor2, Zeiss). RNA extraction and reverse transcription were performed in cells transfected or co-transfected with different plasmids. Effects of IkappaBalpha and its mutants on the transprition level of NF-kappaB, NF-kappaB downstream target gene TNF-alpha, p53 and p53 downstream target gene Bax were observed by real time QT-PCR. In all experiments beta-actin was reference. Results are expressed as the target/reference ratio of the sample divided by the target/reference ratio of the control. Different transfected cells were incubated with CCK-8 for 2 h in the incubator. Then the absorbance at 450 nm was measured by using a microplate reader. RESULTS: Cells that were transfected with p53-DsRed revealed a predominant nuclear localization. YFP-p65 mainly existed in the cytoplasm. Cells were transfected with CFP-IkappaBalpha, CFP-IkappaBalphaM, and CFP-IkappaBalpha243N respectively and revealed a predominant cytosolic localization. However, cells transfected of CFP-IkappaBalpha244C revealed a predominant nuclear localization. The mRNA levels of p65, TNF-alpha, p53 and Bax in CFP-IkappaBalpha transfected cells did not change significantly, while in YFP-p65/CFP-IkappaBalpha co-transfected cells, IkappaBalpha decreased the transcription of p65 downstream gene TNF-alpha (2.24+/-0.503) compared with the YFP-p65/CFP-C1 co-transfected cells (5.08+/-0.891) (P<0.05). Phosphorylation defective IkappaBalpha (IkappaBalphaM) decreased the transcription levels of all the four genes compared with the control (P<0.05). The N terminus of IkappaBalpha (IkappaBalpha243N) increased the transcription of NF-kappaB (1.84+/-0.176) and TNF-alpha (1.51+/-0.203) a little bit. However, the C terminus of IkappaBalpha (IkappaBalpha244C) increased the transcription of NF-kappaB, TNF-alpha, p53 and Bax significantly (8.29+/-1.662, 14.16+/-2.121, 10.2+/-0.621, 3.72+/-0.346) (P<0.05). The CCK-8 experiment also showed that IkappaBalpha244C and p53 synergistically mediate apoptosis. CONCLUSIONS: IkappaBalpha and its mutants (IkappaBalphaM, IkappaBalpha243N, IkappaBalphaM244C) have different effects on NF-kappaB and p53 signaling pathways, according to their different structures. IkappaBalphaM bounds with NF-kappaB and p53 in cytoplasm steadily, and inhibits both of the two signaling pathways. p53 and IkappaBalpha244C may be co-factor in inducing apoptosis. The C terminal of IkappaBalpha enhanced cell death, which suggests that it may be a pro-apoptotic protein existed in cells.

Detection of microRNA in clinical tumor samples by isothermal enzyme-free amplification and label-free graphene oxide-based SYBR Green I fluorescence platform.

MicroRNAs (miRNAs) are a kind of small molecules that involve in many important life activities. They have higher expression levels in many kinds of cancers. In this study, we developed an isothermal enzyme-free amplification (EFA) and label-free graphene oxide (GO)-based SYBR Green I fluorescence platform for detection of miRNA. MiRNA-21 was used as an example to demonstrate the feasibility of the method. Results show that the sensitivity of miRNA-21 is 1pM, and the linearity range is from 1pM to 1nM. The method can specifically discriminate miRNA-21 from miRNA-210 and miRNA-214. Three tumor cell lines of A549, HepG2 and MCF7 were detected by the method. The sensitivities of them were 10(2) cells, 10(3) cells and 10(3) cells respectively. Clinical tumor samples were also tested by this method, and 29 of 40 samples gave out positive signals. The method holds great promise in miRNA detection due to its convenience, rapidness, inexpensive and specificity.

Detection of genetically modified organisms by electrochemiluminescence PCR method.

With the development of biotechnology, more and more genetically modified organisms (GMOs) have entered commercial market. Because of the safety concerns, detection and characterization of GMOs have attracted much attention recently. In this study, electrochemiluminescence polymerase chain reaction (ECL-PCR) combined with hybridization technique was applied to detect the GMOs in genetically modified (GM) soybeans and papayas for the first time. Whether the soybeans and the papayas contain GM components was discriminated by detecting the Cauliflower mosaic virus 35S (CaMV35S) promoter. The experiment results show that the detection limit for CaMV35S promoter is 100 fmol, and the GM components can be clearly identified in GM soybeans and papayas. The technique may provide a new means in GMOs detection due to its simplicity and high efficiency.