A sensitive fluorometric DNA nanobiosensor based on a new fluorophore for tumor suppressor gene detection

Novel indolyl 1,2,4-triazole derivatives as potential anti-proliferative agents: in silico studies, synthesis, and biological evaluation

A new series of indolyl 1,2,4-triazole scaffolds was designed, synthesised, and biologically evaluated for their inhibitory activity against both CDK4 and CDK6. The results ranged from 0.049 μM to 3.031 μM on CDK4 and from 0.075 μM to 1.11 μM on CDK6 when compared to staurosporine, with IC50 values of 1.027 and 0.402 μM, respectively. Moreover, all compounds were tested for their cytotoxicity against two breast cancer cell lines, MCF-7 and MDA-MB-231. All of the synthesised compounds showed promising anti-proliferative activity, with two compounds Vf (IC50 = 2.91 and 1.914 μM, respectively) and Vg (IC50 = 0.891 and 3.479 μM, respectively) having potent cytotoxic activity in comparison to the reference staurosporine (IC50 = 3.144 and 4.385 μM, respectively). Vf and Vg were also found to significantly induce apoptosis to 45.33% and 37.26% (control = 1.91%) where Vf arrested the cell cycle at the S phase while Vg arrested the cycle at the G0/G1 phase. The binding mode and interactions of all compounds were studied and found to mimic those of the FDA approved CDK4/6 inhibitor palbociclib that was used as a reference throughout the study.

An innovative fluorometric bioanalysis strategy towards recognition of DNA methylation using opto-active polymer: A new platform for DNA damage studies by genosensor technology

Efficient pharmacotherapy of cancer is related to accurate recognition of genetic mutations and epigenetic alterations in the early-stage diagnosis. In the present study, a novel optical genosensor based on toluidine blue as photonic probe was developed to detection of DNA methylation using hybridization of pDNA with cDNA. Biomedical analysis was performed using UV-vis and fluorometric methods. For the first time, this strategy was applied for the distinction of methylated DNA from unmethylated-DNA-based on the interaction of optical probe with methylated-DNA and unmethylated DNA. Fluorescence spectroscopic data showed that poly-toluidine blue could be bind to DNA sequences and lead to different fluorescence patterns and could be used as an efficient geno-platform for the sensitive bioassay of mutation. The excitation and emission wavelengths were 580 and 630 nm, respectively. Non-binding of mismatch sequences with the optical probe was used as negative control. Under optimal conditions, linear range was 1 zM to 0.2 pm and the lower limit of quantitation was obtained as target concentrations ranging 1 zM. The designed genosensor showed high capability to distinct methylation from un-methylated. Therefore, the designed DNA-based bioassay could detect DNA methylation significantly. Finally, bioanalysis of real samples showed that the designed genosensor could use to detect DNA methylation which is a new platform for point of care analysis.

A comprehensive review on the applications of nano-biosensor-based approaches for non-communicable and communicable disease detection

The outstretched applications of biosensors in diverse domains has become the reason for their attraction for scientific communities. Because they are analytical devices, they can detect both quantitative and qualitative biological components through the generation of detectable signals. In the recent past, biosensors witnessed significant changes and developments in their design as well as features. Nanotechnology has revolutionized sensing phenomena by increasing biodiagnostic capacity in terms of specificity, size, and cost, resulting in exceptional sensitivity and flexibility. The steep increase of non-communicable diseases across the world has emerged as a matter of concern. In parallel, the abrupt outbreak of communicable diseases poses a serious threat to mankind. For decreasing the morbidity and mortality associated with various communicable and non-communicable diseases, early detection and subsequent treatment are indispensable. Detection of different biological markers generates quantifiable signals that can be electrochemical, mass-based, optical, thermal, or piezoelectric. Speculating on the incumbent applicability and versatility of nano-biosensors in large disciplines, this review highlights different types of biosensors along with their components and detection mechanisms. Moreover, it deals with the current advancements made in biosensors and the applications of nano-biosensors in detection of various non-communicable and communicable diseases, as well as future prospects of nano-biosensors for diagnostics.

Synthesis of a New Series of Nitrogen/Sulfur Heterocycles by Linking Four Rings: Indole; 1,2,4-Triazole; Pyridazine; and Quinoxaline

A new series of nitrogen and sulfur heterocyclic systems were efficiently synthesized by linking the following four rings: indole; 1,2,4-triazole; pyridazine; and quinoxaline hybrids. The strength of the acid that catalyzes the condensation of 4-amino-5-(1H-indol-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 1 with aromatic aldehydes controlled the final product. Reflux in glacial acetic acid yielded Schiff bases 2–6, whereas concentrated HCl in ethanol resulted in a cyclization product at C-3 of the indole ring to create indolo-triazolo-pyridazinethiones 7–16. This fascinating cyclization approach was applicable with a wide range of aromatic aldehydes to create the target cyclized compounds in excellent yield. Additionally, the coupling of the new indolo-triazolo-pyridazinethiones 7–13 with 2,3-bis(bromomethyl)quinoxaline, as a linker in acetone and K₂CO₃, yielded 2,3-bis((5,6-dihydro-14H-indolo[2,3-d]-6-aryl-[1,2,4-triazolo][4,3-b]pyridazin-3 ylsulfanyl)methyl)quinoxalines 19–25 in a high yield. The formation of this new class of heterocyclic compounds in high yields warrants their use for further research. The new compounds were characterized using nuclear magnetic resonance (NMR) and mass spectral analysis. Compound 6 was further confirmed by the single crystal X-ray diffraction technique.

Aligner mediated cleavage of nucleic acids for site-specific detection of single base mismatch

Single base mismatch can always connect with various gene-related diseases, whose determination has aroused widespread interest. So far, various methods have been developed to determine the common base mismatch. However most of them are complex, time-consuming. Herein, we report a novel method, which only need one conventional endonuclease (NEase) and achieve site-specific cleavage in a programmable way, to detect single base mismatch, termed aligner-mediated cleavage-based single base mismatch discrimination (AMCMD). The DNA aligner (DA) is in a stem-loop structure, consistent with an incomplete recognition site of NEase on its stem and a 5'-side arm complementary to the target sequence (TS). Once TS contains matched base and hybridizes with DA, the complete recognition site of NEase is formed, and the TS will be cleavaged with fast speed, while converse is not. Based on it, the method can clearly distinguish mismatched and complementary bases. Without sample pre-processing, we were able to obtain and verify all the test result in about 30 min through the polyacrylamide gel electrophoresis analysis. This endows the proposed method with a simpler advantage. Then we combined AMCMD and EXPAR to create a new method for single base mismatch discrimination, the short sequence obtained by AMCMD as a target to trigger EXPAR, with a detection limit at 1pM level. Another process with human serum underlines that AMCMD is compatible with the complex biological sample, thus it has the potentials for practical applications.

Facile and on-line colorimetric detection of Hg2+based on localized surface plasmon resonance (LSPR) of Ag nanotriangles

A rapid and sensitive colorimetric detection method for the determination of Hg²⁺ has been successfully developed in this research. Citrate-functionalized silver nanotriangles (AgTrngs) were synthesized via one-pot sodium borohydride method with the edge-length range of 30 - 40 nm. The obtained AgTrngs were fully characterized using UV-Vis spectrophotometry, transmission electron microscopy (TEM), energy dispersed spectroscopy (EDS) and X-ray diffractometer. The efficiency of the developed sensor was optimum at pH= 8 due to interfering effect of H⁺ ions for Hg²⁺ under acidic conditions. The successful detection of mercury in aqueous solutions in the concentration range of 10 nmol L^-1-50 μmol L^-1 indicated the applicability of the developed sensor for effective monitoring and controlling the level of Hg²⁺ in industrial effluents. The ability of Hg²⁺ ion to interact with Ag and form the Hg-Ag alloy (amalgam) over the surface of AgTrngs resulted in an obvious color change from blue to violet. UV-Vis spectrophotometry showed that the sensor has the limit of detection (LOD) value of as low as 4 nmol L^-1 which was below the safety level of Hg²⁺ions (10 nmol L^-1) in drinking water. The proposed method can be used for on-line determination of Hg²⁺ in the complex aqueous solutions.