A magnetically assisted surface-enhanced Raman scattering (SERS) biosensor for single-cell detection of S. aureus on the basis of aptamer recognition is reported for the first time. The biosensor ...consists of two basic elements including a SERS substrate (Ag-coated magnetic nanoparticles, AgMNPs) and a novel SERS tag (AuNR–DTNB@Ag–DTNB core–shell plasmonic NPs or DTNB-labeled inside-and-outside plasmonic NPs, DioPNPs). Uniform, monodisperse, and superparamagnetic AgMNPs with favorable SERS activity and magnetic responsiveness are synthesized by using polymer polyethylenimine. AgMNPs use magnetic enrichment instead of repeated centrifugation to prevent sample sedimentation. DioPNPs are designed and synthesized as a novel SERS tag. The Raman signal of DioPNPs is 10 times stronger than that of the commonly used SERS tag AuNR–DTNB because of the double-layer DTNB and the LSPR position adjustment to match the given laser excitation wavelength. Consequently, a strong SERS enhancement is achieved. Under the optimized aptamer density and linker length, capture by aptamer-modified AgMNPs can achieve favorable bacteria arrest (up to 75%). With the conventional Raman spectroscopy, the limit of detection (LOD) is 10 cells/mL for S. aureus detection, and a good linear relationship is also observed between the SERS intensity at Raman peak 1331 cm–1 and the logarithm of bacteria concentrations ranging from 101 to 105 cells/mL. With the help of the newly developed SERS mapping technique, single-cell detection of S. aureus is easily achieved.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
The type A influenza viruses are the most virulent and variable human pathogens with epidemic or even pandemic threat. The development of sensitive, specific and safe field testing methods is in ...particular need and quite challenging. We report here the selection and practical utilization of the inactivated influenza virus-specific aptamers. The DNA aptamers against inactivated intact H1N1 virus particles were identified through the systematic evolution of ligands by exponential enrichment (SELEX) procedure. The discriminative aptamers and their truncated sequences showed selectively high affinity to inactive H1N1 virus and H3N2 virus with the Kd in the low nanomolar range and collective binding properties. The truncated sequences were first applied in a sandwich enzyme-linked oligonucleotide assay (ELONA) with a H1N1 detection limit (LOD, S/N = 3) of 0.3 ng/μL and then in an electrochemical impedance (EIS) aptasensor with more than 300 times improved LOD (0.9 pg/μL) and the excellent selectivity over other viruses (> 100 times). Therefore the developed aptasensors represent the safer, simpler, and possibly better virus-variation adaptable means of virus diagnostics.
Display omitted
•The first aptasensor for the detection of inactivated intact influenza virus.•The first EIS aptasensor for the detection of influenza virus using DNA aptamer.•The first report on the strong impact of probe density on the performance of virus aptasensor.•The direct detection of virus particles with no special requirement on sample pretreatment such as virus lysis.•The developed aptasensors represent the safer, simpler, and possibly better virus-variation adaptable means of virus diagnostics.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Currently, major concerns about the safety and efficacy of RNA interference (RNAi)-based bone anabolic strategies still exist because of the lack of direct osteoblast-specific delivery systems for ...osteogenic siRNAs. Here we screened the aptamer CH6 by cell-SELEX, specifically targeting both rat and human osteoblasts, and then we developed CH6 aptamer-functionalized lipid nanoparticles (LNPs) encapsulating osteogenic pleckstrin homology domain-containing family O member 1 (Plekho1) siRNA (CH6-LNPs-siRNA). Our results showed that CH6 facilitated in vitro osteoblast-selective uptake of Plekho1 siRNA, mainly via macropinocytosis, and boosted in vivo osteoblast-specific Plekho1 gene silencing, which promoted bone formation, improved bone microarchitecture, increased bone mass and enhanced mechanical properties in both osteopenic and healthy rodents. These results indicate that osteoblast-specific aptamer-functionalized LNPs could act as a new RNAi-based bone anabolic strategy, advancing the targeted delivery selectivity of osteogenic siRNAs from the tissue level to the cellular level.
Full text
Available for:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, UILJ, UKNU, UL, UM, UPUK
In this article, a panel of ssDNA aptamers specific to Staphylococcus aureus was obtained by a whole bacterium-based SELEX procedure and applied to probing S. aureus. After several rounds of ...selection with S. aureus as the target and Streptococcus and S. epidermidis as counter targets, the highly enriched oligonucleic acid pool was sequenced and then grouped under different families on the basis of the homology of the primary sequence and the similarity of the secondary structure. Eleven sequences from different families were selected for further characterization by confocal imaging and flow cytometry analysis. Results showed that five aptamers demonstrated high specificity and affinity to S. aureus individually. The five aptamers recognize different molecular targets by competitive experiment. Combining these five aptamers had a much better effect than the individual aptamer in the recognition of different S. aureus strains. In addition, the combined aptamers can probe single S. aureus in pyogenic fluids. Our work demonstrates that a set of aptamers specific to one bacterium can be used in combination for the identification of the bacterium instead of a single aptamer.
Many studies have shown that the quantity and dynamics of circulating tumor cells (CTCs) in peripheral blood of patients afflicted with solid tumours have great relevance in therapeutic efficacy and ...prognosis. Different methods based on various strategies have been developed to isolate and identify CTCs, but their efficacy needs to be improved because of the rarity and complexity of CTCs. This study was designed to examine the possibility of using a SELEX aptamer (BC-15) as a probe to identify rare CTCs out of background nucleated cells. Aptamer BC-15 was selected from a random oligonucleotide library screened against human breast cancer tissue. Fluorescence staining showed that BC-15 had a high affinity for nuclei of human cancer cell lines of various origins as well as CTCs isolated from pancreatic cancer patients, whereas its binding capacity for non-tumor breast epithelial cells and leukocytes was almost undetectable. BC-15+/CD45- cells in cancer patient blood were also found to be cytokeratins 18-positive and aneuploid by immunofluorescence staining and fluorescent in situ hybridization, respectively. Finally, the aptamer method was compared with the well-established anti-cytokeratin method using 15 pancreatic cancer patient blood samples, and enumeration indicated no difference between these two methods. Our study establishes a novel way to identify CTCs by using a synthetic aptamer probe. This new approach is comparable with the anti-cytokeratin-based CTC identification method.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Vasorin (VASN) is a type I transmembrane protein that plays important roles in tumor development and vasculogenesis. In this paper, we showed that VASN could be a key mediator of communication ...between tumor cells and endothelial cells. We confirmed for the first time that HepG2-derived VASN can be transferred to human umbilical vein endothelial cells (HUVECs) via receptor mediated endocytosis of exosomes, at least in part through HSPGs. The HepG2-derived VASN containing exosomes promote migration of recipient HUVECs cells. Our results identify a novel pathway by which a functional protein expressed in tumor cells affects the biological fate of endothelial cells via exosomes.
The development of rapid detection tools for viruses is vital for the prevention of pandemics and biothreats. Aptamers that target inactivated viruses are attractive for sensors due to their improved ...biosafety. Here, we evaluated a DNA aptamer (named as 6.9) that specifically binds to the inactivated SARS-CoV-2 virus with a low dissociation constant (K
= 9.6 nM) for the first time. Based on aptamer 6.9, we developed a fiber-optic evanescent wave (FOEW) biosensor. Inactivated SARS-CoV-2 and the Cy5.5-tagged short complementary strand competitively bound with the aptamer immobilized on the surface of the sensor. The detection of the inactivated SARS-CoV-2 virus was realized within six minutes with a limit of detection (LOD, S/N = 3) of 740 fg/mL. We also developed an electrochemical impedance aptasensor which exhibited an LOD of 5.1 fg/mL and high specificity. We further demonstrated that the LODs of the FOEW and electrochemical impedance aptasensors were, respectively, more than 1000 and 100,000 times lower than those of commercial colloidal gold test strips. We foresee that the facile aptamer isolation process and sensor design can be easily extended for the detection of other inactivated viruses.
Both tumor and adjacent normal tissues are valuable in cancer research. Transcriptional response profiles represent the changes of gene expression levels between paired tumor and adjacent normal ...tissues. In this study, we performed a pan-cancer analysis based on the transcriptional response profiles from 633 samples across 13 cancer types. We obtained two interesting results. Using consensus clustering method, we characterized ten clusters with distinct transcriptional response patterns and enriched pathways. Notably, head and neck squamous cell carcinoma was divided in two subtypes, enriched in cell cycle-related pathways and cell adhesion-related pathways respectively. The other interesting result is that we identified 92 potential pan-cancer genes that were consistently upregulated across multiple cancer types. Knockdown of FAM64A or TROAP inhibited the growth of cancer cells, suggesting that these genes may promote tumor development and are worthy of further validations. Our results suggest that transcriptional response profiles of paired tumor-normal tissues can provide novel perspectives in pan-cancer analysis.
MicroRNAs (miRNAs) are a class of non-coding small RNAs that consist of ≈ 22 nt and are involved in several biological processes by regulating target gene expression. MiR-138 has many biological ...functions and is often downregulated in cancers. Our results showed that overexpression of miR-138 downregulated target RMND5A (required for meiotic nuclear division 5 homolog A) and reduced Exportin-5 stability, which results in decreased levels of pre-miRNA nuclear export in HeLa cells. We also found that miR-138 could significantly inhibit HeLa cell migration by targeting RMND5A. Our study therefore identifies miR-138-RMND5A-Exportin-5 as a previously unknown miRNA processing regulatory pathway in HeLa cells.
PDF
