Implementation of electrochemical impedance spectroscopy to evaluate HER-2 aptamer conjugation to Ecoflex((R)) nanoparticles for docetaxel delivery in breast cancer cells

Abstract

Aptamers are affinity molecules with high specificity, proposed as excellent alternatives to antibodies in targeting and detecting applications due to their smaller size, higher stability, and simplicity of production and modification compared with antibodies. Due to lack of a sensitive and simple method to quantitatively evaluate attachment of aptamer to nanoparticles (NPs), optimization of the attachment process was not considered in most of previously studied aptamer-targeted drug delivery systems. The aim of current study was to demonstrate the utility of electrochemical impedance spectroscopy (EIS) technique in this field. Ecoflex (R) polymeric NPs loaded with docetaxel (DTX-NPs) were fabricated via electrospraying technique, and HER-2-specific aptamer molecules were attached via amide bonds (Apt-DTX-NPs). Using EIS method, the time period of various stages of aptamer conjugation was optimized, by comparing the amount of aptamer molecules attached to the DTX-NPs. The results of in vitro studies on optimum Apt-DTX-NPs demonstrated that the proposed delivery system could significantly enhance the cellular uptake and the cytotoxic effect against HER-2 positive cell line in comparison with non-targeted or Herceptin-targeted DTX-NPs. Thus, aptamer conjugation could improve the in vitro performance of Ecoflex NPs, which could be suggested as a potential DTX delivery system in HER-2 overexpressing cancers. In this regard, EIS method could play its role as a sensitive quantification method to obtain the optimized aptamer-conjugated NP systems. GRAPHICS .