Effect of Serum on Electrochemical Detection of Bioassays Having Ag Nanoparticle Labels

The effect of serum on electrochemical detection of bioassays having silver nanoparticle (AgNP) detection labels was investigated. Both a model assay and an antigen-specific sandwich bioassay for the heart failure marker NT-proBNP were examined. In both cases, the AgNP labels were conjugated to a detection antibody. Electrochemical detection was carried out using a galvanic exchange/anodic stripping voltammetry method in which Au3+ exchanges with AgNP labels. The assays were carried out using a paper-based electrode platform. The bioassays were exposed to different serum conditions prior to and during detection. There are three important outcomes reported in this article. First, both the model- and antigen-specific assays could be formed in undiluted serum with no detectable interferences from the serum components. Second, to achieve the maximum possible electrochemical signal, the highest percentage of serum that can remain in an assay buffer during electrochemical detection is 0.25% when no washing is performed. The assay results are rendered inaccurate when 0.50% or more of serum is present. Third, the factors inhibiting galvanic exchange in serum probably relate to surface adsorption of biomolecules onto the AgNP labels, chelation of Au3+ by serum components, or both. The results reported here provide general guidance for using metal NP labels for electrochemical assays in biofluids.

Synthesis of tunable DNA-directed trepang-like Au nanocrystals for imaging application

Multi-branched metal nanomaterials can exhibit precisely controllable plasmonic properties with the precise control of their sizes and morphologies. In this study, trepang-like gold nanocrystals (AuNCs) with tunable plasmonic properties were synthesized via DNA-directed self-assembly technology. The gold precursor was precisely controlled to be reduced and grow along the DNA skeleton of DNA-conjugated gold nanorods to form multi-branched trepang-like nanocrystals. It was investigated in detail and proven that several key factors greatly influenced the precise control of the morphology and plasmonic property of the proposed AuNCs during their synthesis, including the gold precursor, reducing agent, surfactant, loading amount of DNA and DNA structure. The relative finite-difference time-domain calculation results suggested that the change in the plasmonic resonance peak is consistent with the precise change in the size and morphology of the as-synthesized AuNCs. The trepang-like AuNCs exhibited broad absorption bands in the wavelength range of 700-1100 nm with a high photothermal conversion efficiency of 36.2%. Finally, the trepang-like AuNCs with good biocompatibility were applied in photothermal therapy and imaging analysis.

Counterion coupled (COCO) gemini surfactant capped Ag/Au alloy and core–shell nanoparticles for cancer therapy

In this work hybrid silver (Ag)–gold (Au) nanoparticles (NPs) with different sizes and compositions were synthesized and applied for anticancer evaluations and which is effectively involved in cancer cell apoptosis through DNA damage.