Bacterium-Sculpted Porphyrin-Protein-Iron Sulfide Clusters for Distinction and Inhibition of Staphylococcus aureus.

Microbe-catalyzed surface modification is a promising method for the production of special targeting nanomaterials. A bacterium-selective material can be obtained by investigating the microbe-catalyzed mineralization of proteins. Herein, a novel method was fabricated for the biosynthesis of FeS-decorated porphyrin-protein clusters (P-CA@BE) via E. coli (Escherichia coli)-catalyzed bio-Fe(III) reduction and bio-sulfidation of porphyrin (P), caffeic acid (CA), and protein [bovine serum albumin (BSA)] assemblies. The assembly (P-CA@BSA) was identified by spectroscopic methods. Next, the P-CA@BSA assembly was transferred into FeS-decorated porphyrin-protein clusters (P-CA@BE) catalyzed by E. coli. There are partial ß-folding proteins in P-CA@BE, which selectively recognize S. aureus (Staphylococcus aureus) and show different antibacterial properties against E. coli and S. aureus. Results demonstrate that the E. coli-catalyzed mineralization of the porphyrin-protein assembly is an effective method for the biosynthesis of S. aureus-sensitive metal-protein clusters.

Determination of melamine and melamine-Cu(II) complexes in milk using a DNA-Ag hydrocolloid as the sensor.

Simple and sensitive methods are required for the detection of melamine since melamine is harmful to human health. To detect the content of melamine and metal-melamine species in milk products, a new luminescent DNA silver hydrocolloid (AgNC53) was synthesized using a modified C3A-rich aptamer as the template. The emission of AgNC53 at 617 nm is sensitive to both melamine-Cu(II) and melamine, while almost no response to the free Cu(II) ion was detected. Moreover, AgNC53 is used to detect precisely the content of melamine in milk with a detection limit as low as 2.7 × 10-8 M. Thus, the AgNC53-based fluorescence method is a "label-free" fluorescence technology that can be used for the determination of melamine or the melamine-Cu(II) complex in milk products.

Smart Magnetic Nanoaptamer: Construction, Subcellular Distribution, and Silencing HIF for Cancer Gene Therapy.

Attenuating the expression of HIF-1α (hypoxic inducible factor) by siRNA has an effect on the proliferation of hypoxia cancers. Mitochondria targeting siRNA may silence the level of HIF-1α for cancer gene therapy. A GAG-rich DNA was conjugated to GC-rich DNA for the synthesis of functional magnetic nanoaptamer (DNA-Fe3O4) to keep the innate character of the targeting aptamer. The DNA-Fe3O4 can load the hydrophobic dye (BODIPY-OCH3) by the GC-rich sequences, resulting in fluorescent nanoaptamer (BFe@DNA). Self-assembly of BFe@DNA with target aptamer resulted in the formation of BFe@DNAH. Subcellular fluorescence imaging results confirm that BFe@DNAH can accumulate in MCF-7 cells and selectively target mitochondrion. In particular, BFe@DNAH can transport siRNA to breast cancer cells or tissues for the attenuation of HIF-1α and ATP and the inhibition on growth of cancer cells in vivo. Therefore, BFe@DNAH is a smart nanoaptamer platform for the development of subcellular imaging agents and gene therapy.

A near-infrared BSA coated DNA-AgNCs for cellular imaging.

Near-infrared silver nanoclusters, have potential applications in the field of biosensing and biological imaging. However, less stability of most DNA-AgNCs limits their application. To obtain stable near-infrared fluorescence DNA-AgNCs for biological imaging, a new kind of near-infrared fluorescent DNA-Ag nanoclusters was constructed using the C3A rich aptamer as a synthesis template, GAG as the enhancer. In particular, a new DNA-AgNCs-Trp@BSA was obtained based on the self-assembly of bovine serum albumin (BSA) and tryptophan loaded DNA-AgNCs by hydrophobic interaction. This self-assembly method can be used to stabilize DNAn-Ag (n = 1-3) nanoclusters. Hence, the near-infrared fluorescence DNA-AgNCs-Trp@BSA was applied in cellular imaging of HepG-2 cells.

Mn(ii) silver-aptamer clusters for targeted MR imaging of tumors.

Hypoxia-inducible factor (HIF) highly expressed in most of the cancer cells. The Mn(ii)-aptamer based nanoclusters with 3D structures would be HIF-aptamer based targeted magnetic resonance imaging agents for cancer MRI diagnosis. Herein, a new class of contrast agent Mn(ii) silver-aptamer clusters (AdpaMn@DNA-Ag-DNAG1) were constructed based on the assembly of DNA-mediated Ag nanoclusters (DNA-AgNCs) with the Mn(ii) complex (AdpaMn) and DNAG1, the recognition sequence of GLUT-1. Then, the Mn(ii) silver-aptamer clusters (AdpaMn@DNA-Ag-DNAG1) are used as the MRI agents both in vitro and in vivo. The results show that the MRI signal is clearly presented in the tumor position. Consequently, the Mn(ii) silver-aptamer clusters can be used as a new class of contrast agents for targeted MR imaging of tumors.