No abstract

The sizes, shapes, and surface characteristics of nanomaterials determine their unique physical, chemical, and biological properties. Localized surface plasmon resonance (LSPR) is one of the unique optical properties of noble-metal nanoparticles. The synthesis of nanomaterials using biomolecules as templates offers an excellent strategy to control and regulate their features. Herein, for the first time, we demonstrate a green synthesis approach of silver nanoparticles (AgNPs) using nucleotide-based assemblies as templates. Moreover, we investigate the influence of different nucleotide-based assemblies and metal ions on the preparation of AgNPs, implying that AgNPs with different LSPR absorptions originating from their surrounding and size could be synthesized. The synthetic route is green, energy-effective, and feasible. On the basis of the unique LSPR-controlled property, the AgNP composites were applied for cryptography, biothiol detection, and designing logic gates. This work offers a promising method for the synthesis of nanomaterials with multiapplications.

A novel electrochemical sensor was developed based on the combination of polythionine (PTH)/gold nanoparticle (nanoAu) composite film and enzyme catalysis amplification for the indirect competitive immunoassay of ochratoxin A (OTA). The sensing substrate was fabricated using a glassy carbon electrode (GCE) modified with an electropolymerized film of polythionine, which then mediated the self-assembly of nanoAu monolayer. After OTA-ovalbumin conjugates (OTA-OVA) were adsorbed onto the surface-confined gold nanoparticles, the analyte OTA in sample solution competed for the limited anti-OTA monoclonal antibodies with the immobilized hapten. Alkaline phosphatase (ALP)-labeled horse anti-mouse IgG antibodies were selectively bound onto the surface of the electrode, which afforded an indicator for OTA concentration in the sample. Under the optimal conditions, electrochemical response arising from the oxidation of enzymatic product of 1-naphthyl phosphate was observed to be inversely proportional to OTA concentration in the range from 1 ng mL À1 to 1000 ng mL À1 with a detection limit as low as 0.2 ng mL À1 . In addition, good reproducibility, high selectivity, sensitivity and stability were achieved. The recovery test demonstrated the feasibility of the proposed method for accurate determination of OTA contaminated samples.