Synthesis and Assessment of DNA/Silver Nanoclusters Probes for Optimal and Selective Detection of Tristeza Virus Mild Strains

A fluorescent aptasensor based on copper nanoclusters for optical detection of CD44 exon v10, an important isoform in metastatic breast cancer

Recent studies suggest that breast cancer cells express various CD44 isoforms. CD44 is an integral transmembrane protein encoded by a single 20-exon gene. Exon v10 of CD44 plays a critical role in promoting cancer metastasis, so sensitive detection of this isoform helps in early diagnosis of metastatic breast cancer and facilitates the treatment process. This study aimed to use v10-specific aptamers to set up an optical aptasensor based on fluorescent metal nanoclusters. For this purpose, nanoclusters of silver, gold, and copper were prepared by different CD44 v10 DNA aptamers as molecular templates. UV-vis, TEM, and fluorescence spectrometer results confirmed the accuracy and quality of the synthesized aptamer-templated nanoclusters (Apt-NCs). Finally, we compared the performance of the as-prepared Apt-NCs in response to different cultured cell lines. According to the results, the optical response of M-Apt4-CuNCs was more efficient and correlated well with the concentrations of CD44 v10-enriched cells. The detection limit of the aptasensor was 40 ± 5 cells per mL.

Biomolecule conjugated metal nanoclusters: bio-inspiration strategies, targeted therapeutics, and diagnostics

To help those suffering from viral infections and cancers, scientists are exploring enhanced therapeutic methods via metal nanoclusters (MNCs).

A luminescence nanosensor for Ornidazole detection using graphene quantum dots entrapped in silica molecular imprinted polymer

A luminescence nanosensor has been developed for analysis of Ornidazole in biological samples using graphene-quantum-dot-embedded silica molecular imprinted polymer (GQD-SMIP) as a selective probe for this analyte. The GQD-SMIP was found to possess a strong fluorescent emission at 450 nm upon excitation at 365 nm. This emission was found to linearly quench in the presence of Ornidazole in a concentration range of 0.75 to 30 μM. A detection limit of 0.24 μM was reached using the probe and the sensor was successfully used in the determination of the analyte in plasma samples.

Detection of large deletion in human BRCA1 gene in human breast carcinoma MCF-7 cells by using DNA-Silver Nanoclusters

Here we describe a label-free detection strategy for large deletion mutation in breast cancer (BC) related gene BRCA1 based on a DNA-silver nanocluster (NC) fluorescence upon recognition-induced hybridization. The specific hybridization of DNA templated silver NCs fluorescent probe to target DNAs can act as effective templates for enhancement of AgNCs fluorescence, which can be used to distinguish the deletion of BRCA1 due to different fluorescence intensities. Under the optimal conditions, the fluorescence intensity of the DNA-AgNCs at emission peaks around 440 nm (upon excitation at 350 nm) increased with the increasing deletion type within a dynamic range from 1.0 × 10^-10 to 2.4 × 10^-6 M with a detection limit (LOD) of 6.4 × 10^-11 M. In this sensing system, the normal type shows no significant fluorescence; on the other hand, the deletion type emits higher fluorescence than normal type. Using this nanobiosensor, we successfully determined mutation using the non-amplified genomic DNAs that were isolated from the BC cell line.

Detection of p53 Gene Mutation (Single-Base Mismatch) Using a Fluorescent Silver Nanoclusters

P53 mutation was detected through the application of a biosensing approach based on the decrease in the fluorescence of oligonucleotide-templated silver nanoclusters (DNA-AgNCs). To this end specific DNA scaffolds of two various nucleotide fragments were used. One of the scaffolds was enriched with two cytosine sequence fragment (C12). This led to DNA-AgNCs with a fluorescence intensity through chemical reduction, while the other scaffold acted as the probe fragment (5- GTAGATGGCCATGGCGCGGACGCGGGTG-3). This latter scaffold selectively bound to the specific p53 site. Thus, resulting AgNCs demonstrated decreased fluorescence upon binding to single-base mismatching targets, and this behavior was found to be linearly proportional to the concentration of mutated p53 from 5 to 350 nM and the approach was found to be able to detect concentrations as low as 1.3 nM.

Rapid pre-symptomatic recognition of tristeza viral RNA by a novel fluorescent self-dimerized DNA–silver nanocluster probe

Citrus tristeza virus (CTV), a positive-strand RNA virus within the family of Closteroviridae, is distributed worldwide and causes one of the most economically important diseases of citrus.