Tuning quantum dots emission on DNA tetrahedron/silica nanosphere/graphene oxide nanointerface for ratiometric fluorescence assay of Pb2+ in multiplex samples.

BACKGROUND: Assembling framework nucleic acid (FNA) nanoarchitectures and tuning luminescent quantum dots (QDs) for fluorescence assays represent a versatile strategy in analytical territory. Rationally, FNA constructs could offer a preferential orientation to efficiently recognize the target and improve detection sensitivity, meanwhile, regulating size-dependent multicolor emissions of QDs in one analytical setting for ratiometric fluorescence assay would greatly simplify operation procedures. Nonetheless, such FNA/QDs-based ratiometric fluorescence nanoprobes remain rarely explored. RESULTS: We designed a sensitive and signal amplification-free fluorescence aptasensor for lead ions (Pb2+) that potentially cause extensive contamination to environment, cosmetic, food and pharmaceuticals. Red and green emission CdTe quantum dots (rQDs and gQDs) were facilely prepared. Moreover, silica nanosphere encapsulating rQDs served as quantitative internal reference and scaffold to anchor a predesigned FNA and DNA sandwich containing Pb2+ binding aptamer and gQD modified DNA signal reporter. On binding of Pb2+, the gQD-DNA signal reporter was set free, resulting in fluorescence quenching at graphene oxide (GO) interface. Owing to the rigid structure of FNA, the fluorescence signal reporter orderly arranged at the silica nanosphere could sensitively respond to Pb2+ stimulation. The dose-dependent fluorescence signal-off mode enabled ratiometric analysis of Pb2+ without cumbersome signal amplification. Linear relationship was established between fluorescence intensity ratio (I555/I720) and Pb2+ concentration from 10 nM to 2 µM, with detection limit of 1.7 nM (0.43 ppb), well addressing the need for Pb2+ routine monitoring. The designed nanoprobe was applied to detection of Pb2+ in soil, cosmetic, milk, drug, and serum samples, with the sensitivity comparable to conventional ICP-MS technique. SIGNIFICANCE: Given the programmable design of FNA and efficient recognition of target, flexible tuning of QDs emission, and signal amplification-free strategy, the present fluorescence nanoprobe could be a technical criterion for other heavy metal ions detection in a straightforward manner.

Framework Nucleic Acid-Based Multifunctional Tumor Theranostic Nanosystem for miRNA Fluorescence Imaging and Chemo/Gene Therapy.

Intelligent stimulus-responsive theranostic systems capable of specifically sensing low-abundance tumor-related biomarkers and efficiently killing tumors remain a pressing endeavor. Here, we report a multifunctional framework nucleic acid (FNA) nanosystem for simultaneous imaging of microRNA-21 (miR-21) and combined chemo/gene therapy. To achieve this, two FNA nanoarchitectures labeled with Cy5/BHQ2 signal tags were designed, each of which contained an AS1411 aptamer, two pairs of DNA/RNA hybrids, a pH-sensitive DNA catcher, and doxorubicin (DOX) intercalating between cytosine and guanine in the tetrahedral DNA nanostructure (TDN). In the acidic tumor microenvironment, the DNA catchers spontaneously triggered to form an i-motif and create an FNA dimer (dFNA) while releasing DOX molecules to exert a cytotoxic effect. In addition, the overexpressed miR-21 in tumor cells dismantled the DNA/RNA hybrids to produce vascular endothelial growth factor-associated siRNA via a toehold-mediated strand displacement reaction, thus enabling a potent RNA interfering. Also importantly, the liberated miR-21 could initiate cascade-reaction amplification to efficiently activate the Cy5 signal reporters, thereby realizing on-site fluorescence imaging of miR-21 in living cells. The exquisitely designed FNA-based nanosystem showed favorable biocompatibility and stability as well as acid-driven DOX release characteristics. Owing to the aptamer-guided targeting delivery, specific uptake of the FNA-based theranostic nanosystem by HepG2 cells was verified with confocal laser scanning microscopy and flow cytometry analyses, which therefore resulted in apoptosis of HepG2 cells while doing minimal damage to normal H9c2 and HL-7702 cells. Strikingly, both in vitro and in vivo experiments demonstrated the achievements of the FNA-enabled miR-21 imaging and synergistically enhanced chemo/gene therapy. This work thus represents a noteworthy advance on the FNA-based theranostic strategy that can effectively avoid the undesirable premature leakage of anticarcinogen and off-target of siRNA, and achieve on-demand reagents release for tumor diagnostics and treatment.

An inorganic-organic-polymeric nanovehicle for targeting delivery of doxorubicin: Rational assembly, pH-stimulus release, and dual hyperthermia/chemotherapy of hepatocellular carcinoma.

Efficiently synergistic therapy of hepatocellular carcinoma (HCC) by chemotherapeutic drug and photothermal agent remains a considerable challenge. Here, we report a nanodrug that integrates specific hepatoma-targeted delivery, pH-triggered drug release, and cooperative photothermal-chemotherapy function. By grafting the easily self-assembled CuS@polydopamine (CuS@PDA) nanocapsulation with polyacrylic acid (PAA), an inorganic-organic-polymeric hybrid nanovehicle was developed as a dual photothermal agent and carrier for loading antitumor drug-doxorubicin (DOX) through electrostatic adsorption and chemical linking antibody against GPC3 commonly overexpressed in HCC, resulting in the nanodrug, CuS@PDA/PAA/DOX/GPC3. The multifunctional nanovehicle had excellent biocompatibility, stability, and high photothermal conversion efficiency, due to the rationally designed binary CuS@PDA photothermal agent. The 72-h accumulative drug release in pH 5.5 tumor microenvironment can reach up to 84%, far higher than 15% measured in pH 7.4 condition. Notably, in contrast to the merely 20% survival rate of H9c2 and HL-7702 cells exposed to free DOX, their viabilities in the nanodrug circumstance can maintain 54% and 66%, respectively, suggesting the abated toxicity to the normal cell lines. When exposed to the hepatoma-targeting nanodrug, the viability of HepG2 cells was found to be 36%, which further drastically declined to 10% plus 808-nm NIR irradiation. Moreover, the nanodrug is potent to cause tumor ablation in HCC-modeled mice, and the therapeutic efficacy can be greatly enhanced under NIR stimulus. Histology analyses reveal that the nanodrug can effectively alleviate the chemical damage to heart and liver, as compared to free DOX. This work thus offers a facile strategy for design of targeting anti-HCC nanodrug toward combined photothermal-chemotherapy.

2,3,5,6-Tetra-fluoro-1,4-bis-({[(thio-phen-2-yl)methyl-idene]amino}-meth-yl)benzene.

In the title compound, C18H12F4N2S2, a bis-thio-phenyl Schiff base ligand with a perifluorinated aromatic core, the complete molecule is generated by crystallographic inversion symmetry. The thio-phene and tetra-fluorinated benzene rings are oriented at a dihedral angle of 77.38 (4)°. The crystal structure exhibits C-H⋯F hydrogen bonds, resulting in supra-molecular chains along the c-axis direction.

2,3,5,6-Tetra-fluoro-1,4-bis-({[(5-methyl-thio-phen-2-yl)methyl-idene]amino}-meth-yl)benzene.

The title compound, C20H16F4N2S2, is a flexible bis-thio-phene-type Schiff base ligand with a perfluorinated backbone. The terminal thio-phene rings are almost normal to one another with a dihedral angle of 83.8 (2)°, and they are tilted to the central tetra-fluorinated benzene ring with dihedral angles of 61.2 (2) and 77.7 (1)°. In the crystal, there are π-π inter-actions involving the benzene ring and the thiophene ring of a symmetry-related molecule with a centroid-centroid separation of 3.699 (3) Å.

Dual effects of hydrogen sulphide on focal cerebral ischaemic injury via modulation of oxidative stress-induced apoptosis.

1. Hydrogen sulphide (H2S), one of three signalling gasotransmitters, plays an important role in oxidative stress and apoptosis. However, the effects of H2S on oxidative stress-induced apoptosis in focal cerebral ischaemic injury in rats have not been clarified. 2. In the present study, sodium hydrosulphide (NaHS) was used as the H2S donor. Eighty-four Sprague-Dawley rats were randomly divided into six groups: sham, sham + low-dose (2.8 mg/kg) NaHS, sham + high-dose (11.2 mg/kg) NaHS, infarct, infarct + low-dose NaHS and infarct + high-dose NaHS. The focal cerebral ischaemic model was created by cranially inserting a nylon thread with a rounded tip into an internal carotid artery. Rats were killed 21 h after administration of NaHS. 3. In the infarct + low-dose NaHS compared with infarct group, infarct volume was significantly decreased and injury to the mitochondria in nerve cells was mitigated. Furthermore, significant increases were seen in mitochondrial superoxide dismutase and glutathione peroxidase activity and neuronal bcl-2 protein levels, whereas mitochondrial malondialdehyde content and neuronal bax and caspase 3 protein levels were significantly decreased, in the infarct + low-dose NaHS compared with infarct group. The effects seen in the infarct group were significantly aggravated in the infarct + high-dose NaHS group. 4. The findings of the present study provide novel evidence for the dual effects of H2S on focal cerebral ischaemic injury via modulation of oxidative stress-induced apoptosis.