Multifunctional silver nanocluster-hybrid oligonucleotide vehicle for cell imaging and microRNA-targeted gene silencing.

Novel therapeutics is urgently needed to prevent cancer-related deaths. MicroRNAs that act as tumor suppressors have been recognized as a next-generation tumor therapy, and the restoration of tumor-suppressive microRNAs using microRNA replacements or mimics may be a less toxic, more effective strategy due to fewer off-target effects. Here, we designed the novel multifunctional oligonucleotide nanocarrier complex composed of a tumor-targeting aptamer sequence specific to mucin 1 (MUC1), poly-cytosine region for fluorescent silver nanocluster (AgNC) synthesis, and complimentary sequence for microRNA miR-34a loading. MiR-34a was employed because of its therapeutic effect of inhibiting oncogene expression and inducing apoptosis in carcinomas. By monitoring the intrinsic fluorescence of AgNC, it was clearly shown that the constructed complex (MUC1-AgNCm-miR-34a) enters MCF-7 cells. To evaluate the efficacy of this nanocarrier for microRNA delivery, we investigated the gene and protein expression levels of downstream miR-34a targets (BCL-2, CDK6, and CCND1) by quantitative PCR and western blotting, respectively, and the results indicated their effective inhibition by miR-34a. This novel multifunctional AgNC-based nanocarrier can aid in improving the efficacy of breast cancer theranostics.

Oligonucleotides as 'bio-solvent' for in situ extraction and functionalisation of carbon nanoparticles.

A simple yet novel one-pot approach is developed to prepare carbon nanoparticles with diameters of ∼2 nm and modified by oligonucleotides. We use single-stranded deoxyribonucleic acid (ssDNA), which serves as a unique 'bio-solvent' for carbon nanoparticle (CNP) preparation and as a target molecule for functionalisation. Proposed interactions relevant to the stabilisation of the final oligonucleotide-CNP complex include π-π stacking and π-HN bonding with sp2 carbon atoms on the CNP surface. Furthermore, oligonucleotide-enriched CNPs can be readily extracted within seconds from a crude mixture of single-walled carbon nanotubes (SWCNTs) without any need for post-synthesis chemical modification. The established CNPs are biocompatible, possess intrinsic fluorescence, and do not result in the undesirable photobleaching effect, rendering them potential candidates for in vivo biological applications.