A novel bioassay based gold nanoribbon biosensor to aid the preclinical evaluation of anticancer properties

In this work, we report a microbial biosensor fabricated for the preclinical assay of anticancer compounds. Gold nanoribbons were used as a transducer for mounting the microbe. For the synthesis of these unique Au nanostructures, quercetin stabilized gold nanoparticles (Q-AuNPs) were synthesized as a first step using onion peel. Later, dityrosine peptide was used as a sacrificial template for the synthesis of the gold nanoribbons (AuNRs). The structural morphology of the as-synthesized Au nanomaterial was examined using UV spectroscopy, XRD, SEM and TEM. The AuNRs were found to be <10 nm in diameter, which provided a good biocompatible environment and effective protection for the immobilization of Agrobacterium tumefaciens (At), a causative agent of crown gall disease. At is reported to cause tumors in plants through a tumorigenic mechanism similar to that of humans. Inhibition of At indicates that the inhibitory compound being screened exhibits anticancer activity. Clitoria ternatea (Ct) is traditionally used to cure many diseases and is known to possess anticancer activity. Therefore, we have used a Ct flower extract in the preclinical study of its anticancer activity against At by fabricating a simple electrochemical sensor. We have employed electrochemical techniques such as CV and EIS for the characterization of the developed microbial biosensor. Moreover, the as-synthesized AuNRs behave as an ideal transducer and platform, thus improving the electrode surface area and providing good biocompatibility for the immobilization of At. In contrast to other immobilization techniques and biosensors that often require elaborate procedures, cross-linking agents and rigorous chemical reactions, At was directly adsorbed onto the electrode under optimum conditions without any mediators. The results show that the developed biosensor is useful in the pre-clinical analysis of anticancer properties. Indeed the study examines the use of electrochemistry, demonstrating the rapid response and high sensitivity of the proposed sensor in contrast to bioassay procedures. In conclusion, the experimental results indicate that the developed biosensor accentuates the excellent properties of the synthesized AuNRs, which promises to be a novel avenue in designing biosensors. © 2016 The Royal Society of Chemistry.1

An Electrochemical Perspective Assay for Anticancer Activity of Calotropis Procera Against Glioblastoma Cell Line (LN-18) using Carbon Nanotubes-Graphene Nano-Conglomerate as a Podium

In this article, we report the pre-screening of anti-cancer effect of Calotropis procera against glioblastoma cell lines (LN-18) by means of electrochemical methods. Soxhlet assisted extraction (SAE) has been employed to extract the polyphenol contents present in the leaf of Calotropis procera. The phytochemical analysis of the extract has been studied and the polyphenol contents were determined using Folin Ciocalteau method. To study the anticancer effects of the aqueous plant extract, a cytosensor (Gr/NT-G/LN-18) was fabricated and its possible mechanism for DNA binding was studied using graphite /poly(allylamine hydrochloride)/nanotube-graphene composite /polypyrrole /de-oxy ribonucleic acid (Gr/PAH/NT-G/PPy/DNA) modified electrode. The electrochemical characteristics of the proposed Gr/NT-G/LN-18 cytosensor towards the plant extract were evaluated using electrochemical techniques like cyclic voltammetry and differential pulse voltammetry. Scanning electron microscopy (SEM) and energy dispersive analysis of x-ray (EDAX) have been employed to study the physical characterization of the Gr/PAH/NT-G/PPy/DNA modified electrode. These results indicate that the plant extract has an ability to act as an antiglioblastoma against LN-18 cancer cells. Copyright © 2016 VBRI Press.

Amperometric hydrogen peroxide and cholesterol biosensors designed by using hierarchical curtailed silver flowers functionalized graphene and enzymes deposits

Novel flower-like silver particles with triangular plates as building block along with functionalized graphene (straggled sheets) and enzymes horseradish peroxidase (HRP) or cholesterol oxidase (ChOx), were obtained on graphite electrode by galvanostatic electrodeposition method. The morphology of the electrodeposits has been characterized using scanning electron microscopy and energy-dispersive analysis of X-ray. The resulting biosensors named Nf/(HRP-f-graphene-Ag)/Gr and Nf/(ChOx-f-graphene-Ag)/Gr were evaluated for electrochemical activity using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry. Optimization of the interdependent experimental parameters such as pH and temperature were achieved and maintained constant throughout the experiments. An activation energy of 2.5 kJ mol -1 was obtained for Nf/(HRP-f-graphene-Ag)/Gr electrode while Nf/(ChOx-f-graphene-Ag)/Gr showed an activation energy of 2.06 and 3.12 kJ mol-1. Furthermore, the former electrode demonstrated a good linear range of 25 μM to 19.35 mM with rapid response time of 3 s and detection limit of 5 μM for hydrogen peroxide. Similarly, the Nf/(ChOx-f-graphene-Ag)/ Gr electrode revealed a linear range of 0.1-4.5 mM with rapid response time of 3 s and an excellent detection limit of 0.514 mM for cholesterol. Besides this, the Nf/(HRP-f-graphene-Ag)/Gr and Nf/(ChOx-f-graphene-Ag)/Gr electrodes displayed a Michaelis-Menten constant of 0.26 and 0.57 mM, respectively, suggesting high affinity and enzymatic activity. The enhanced performance of biosensors towards detection of substrate and rejection of interferents, provided an evidence for its high anti-interference ability. Additionally the biosensors exhibit long term storage stability and reproducibility with antifouling properties. © 2013 Springer-Verlag Berlin Heidelberg.