DSN signal amplification strategy based nanochannels biosensor for the detection of miRNAs.

MiRNA-21 is recognized as an important biological marker for the diagnosis, treatment, and prognosis of breast cancer. Here, we have created a nanochannel biosensor utilizing the duplex-specific nuclease (DSN) signal amplification strategy to achieve the detection of miRNAs. In this system, DNA as the capture probe was covalently immobilized on the surface of nanochannels, which hybridized with the target miRNA and forms RNA/DNA duplexes. DSN could cleave the probe DNA in RNA/DNA duplexes, recycling target miRNA, which may again hybridized with other DNA probes. After N cycles, most of the DNA probes had been cleaved, and the content of miRNA could be quantified by detecting changes in surface charge density. This biosensor can distinguish miR-21 from non-complementary miRNAs and one-base mismatched miRNAs, with reliable detection limits as low as 1 fM in PBS. In addition, we had successfully applied this method to analysis of total RNA samples in MCF-7 cells and HeLa cells, and the nanochannels had also shown excellent responsiveness and strong anti-interference ability. This new method is expected to contribute to miRNA detection in clinical diagnostics, providing a unique approach to detecting and distinguishing disease-associated molecules.

Integrated FET sensing microsystem for specific detection of pancreatic cancer exosomal miRNA10b.

Tumor-derived exosome (TD-Ex) serves as a crucial early diagnostic biomarker of pancreatic cancer (PC). However, accurate identification of TD-Ex from PC is still a challenging work. In this paper, a detection microsystem that integrates magnetic separation and FET biosensor is developed, which is capable of selectively separating TD-Ex of PC from the plasma and detecting exosomal miRNA10b in a sensitive and specific manner. The magnetic beads were functionalized with dual antibody (GPC-1 antibody and EpCAM antibody), enabling selective recognition and capture of PC-derived exosomes. On the other hand, a peptide nucleic acid (PNA)- functionalized reduced graphene oxide field-effect transistor (RGO FET) biosensor was subsequently utilized to detect the exosomal miRNA10b, which is highly expressed in PC- derived exosomes. This system could achieve a low detection limit down to 78 fM, and selectively identify miRNA10b from single-base mismatched miRNA. In addition, 40 clinical plasma samples were tested with this microsystem, and the results indicate that it could effectively distinguish PC patients from healthy individuals. The assay combines specific capture and enrichment of PC-derived exosomes with sensitive and selective detection of exosomal miRNA, showing its potential to be used as an effective scheme for PC early diagnosis.

Peptide Nucleic Acid-Functionalized Nanochannel Biosensor for the Highly Sensitive Detection of Tumor Exosomal MicroRNA.

Compared with free miRNAs in blood, miRNAs in exosomes have higher abundance and stability. Therefore, miRNAs in exosomes can be regarded as an ideal tumor marker for early cancer diagnosis. Here, a peptide nucleic acid (PNA)-functionalized nanochannel biosensor for the ultrasensitive and specific detection of tumor exosomal miRNAs is proposed. After PNA was covalently bound to the inner surface of the nanochannels, the detection of tumor exosomal miRNAs was achieved by the charge changes on the surface of nanochannels before and after hybridization (PNA-miRNA). Due to the neutral characteristics of PNA, the efficiency of PNA-miRNA hybridization was improved by significantly reducing the background signal. This biosensor could not only specifically distinguish target miRNA-10b from single-base mismatched miRNA but also achieve a detection limit as low as 75 aM. Moreover, the biosensor was further used to detect exosomal miRNA-10b derived from pancreatic cancer cells and normal pancreatic cells. The results indicate that this biosensor could effectively distinguish pancreatic cancer tumor-derived exosomes from the normal control group, and the detection results show good consistency with those of the quantitative reverse-transcription polymerase chain reaction method. In addition, the biosensor was used to detect exosomal miRNA-10b in clinical plasma samples, and it was found that the content of exosomal miRNA-10b in cancer patients was generally higher than that of healthy individuals, proving that the method is expected to be applied for the early diagnosis of cancer.

Cyclic hydroxyamidines as amide isosteres: discovery of oxadiazolines and oxadiazines as potent and highly efficacious γ-secretase modulators in vivo.

Cyclic hydroxyamidines were designed and validated as isosteric replacements of the amide functionality. Compounds with these structural motifs were found to be metabolically stable and to possess highly desirable pharmacokinetic profiles. These designs were applied in the identification of γ-secretase modulators leading to highly efficacious agents for reduction of central nervous system Aß(42) in various animal models.

Discovery of cyclic acylguanidines as highly potent and selective beta-site amyloid cleaving enzyme (BACE) inhibitors: Part I--inhibitor design and validation.

A number of novel amidine containing heterocycles were designed to reproduce the unique interaction pattern, revealed by X-ray crystallography, between the BACE-1 catalytic diad and a weak NMR screening hit (3), with special attention paid to maintaining the appropriate basicity and limiting the number of H-bonding donors of these scaffolds. The iminohydantoin cores (10 and 23) were examined first and found to interact with the catalytic diad in one of two binding modes (A and B), each with the iminohydantoin core flipped 180 degrees in relation to the other. The amidine structural motif within each core forms a bidentate interaction with a different aspartic acid of the catalytic diad. Both modes reproduced a highly conserved interaction pattern between the inhibitors and the catalytic aspartates, as revealed by 3. Potent iminohydantoin BACE-1 inhibitors have been obtained, validating the molecular design as aspartyl protease catalytic site inhibitors. Brain penetrant small molecule BACE inhibitors with high ligand efficiencies have been discovered, enabling multiple strategies for further development of these inhibitors into highly potent, selective and in vivo efficacious BACE inhibitors.

Discovery and SAR of cyclic isothioureas as novel NPY Y1 receptor antagonists.

A class of novel 2-aminobenzothiazoles have been identified as NPY Y(1) antagonists. Various N-heterocyclic substituted aminophenethyl-2-aminobenzothiazole analogs were synthesized to explore the SAR. Isothiourea analogs and ligands with high potency (K(i) 30 nM) have been identified.

Design and discovery of 1,3-benzodiazepines as novel dopamine antagonists.

A series of novel 1,3-benzodiazapine based D1 antagonists was designed according to the understanding of pharmacophore models derived from SCH 23390 (1b), a potent and selective D1 antagonist. The new design features an achiral cyclic-amidine that maintains desired basicity. Solid phase synthesis was developed for SAR development of the novel dopamine antagonists.

Synthesis and antitumor activity of sulfur-containing 9-anilinoacridines.

A series of sulfur-containing 9-anilinoacridines related to amsacrine were synthesized and evaluated for their anticancer potential. Among the compounds, both diol-containing compounds, 2a and 3, were the most cytotoxic of the sulfide series against V-79 cells in vitro (IC(90) = 2.1 microM and 1.9 microM, respectively). Among the non-alkyl-substituted compounds (7-9), compounds with electron-donating substitution para to the sulfide (7 and 9) were more cytotoxic than the electron-withdrawing nitro-substituted compound 8. The limited SAR suggested the importance of hydroxyl functionality along with its location for the cytotoxicity in the series. A preliminary anticancer screening against P388 leukemia showed that 2a is highly active in vivo as well. Topoisomerase II inhibitory activity appeared to be involved in the cytotoxicity of compound 2a. Sulfoxide compound 2b, which is 6-7-fold less cytotoxic than its sulfide 2a, appears to be a potential bioreductive anticancer prodrug on the basis of its bioreductive metabolism findings.