Heparin‐gold Nanoparticles and Liquid Crystal Applied in Label‐free Electrochemical Immunosensor for Prostate‐specific Antigen

Abstract

A label‐free electrochemical immunosensor based on the liquid crystal (E)‐1‐decyl‐4‐[(4‐decyloxyphenyl)diazenyl]pyridinium bromide (Br−Py), together with heparin‐stabilized gold nanoparticles (AuNP‐Hep) and Nafion is proposed for the determination of prostate‐specific antigen (PSA). The Br−Py liquid crystal presented redox properties and good film‐forming abilities on the electrode surface, and thus it is a suitable alternative as a redox probe for a label‐free electrochemical immunosensor, which could simplify the analysis methodology. The stepwise construction of the immunosensor and the incubation process (immunocomplex formation) were characterized by voltammetry and electrochemical impedance spectroscopy. The proposed immunosensor could directly detect PSA concentrations in the incubation samples, based on the suppression of the Br−Py redox peak (‘base peak’) current. After optimization, the immunosensor exhibited a linear response to PSA concentrations in the range of 0.1 to 50 ng mL−1, with a calculated detection limit of 0.08 ng mL−1. The reproducibility (coefficient of variance less than 3.0 %), selectivity and accuracy of the methodology were adequate. The immunosensor was satisfactorily applied in the quantification of PSA in human blood plasma samples.

Heparin-stabilized gold nanoparticles embedded in graphene for the electrochemical determination of esculetin

“…The procedure for the synthesis of gold nanoparticles stabilized with heparin (AuNPs-Hep) was carried out as described by Talamini et al 33 Initially, 100 μL of 0.12 mol L −1 HAuCl 4 was added to 10.0 mL of heparin solution (0.5% w/v). After that, 200 μL of NaBH 4 (20 mmol L −1 ) was added and the solution was kept under agitation for 30 minutes.…”

“…31,32 Heparin can act as a stabilizing agent because it has an abundance of functional groups, such as ether oxygen, hydroxyl and sulphonic, which can be anchored on the metal surface through ion–dipole interactions. 33 In addition, the sulfonic groups of heparin can mainly interact with gold nanoparticles (AuNPs). AuNPs are utilized to enhance the sensitivity of electrochemical sensors, because of their excellent catalytic and conductive properties.…”

Review—Recent Advances in Electrochemical Detection of Prostate Specific Antigen (PSA) in Clinically-Relevant Samples

“…This configuration produces a signal-off sensor where the change in signal is dictated by steric hindrance caused by surface capture of PSA. 39,55,44,47,51,56 Çevik et al constructed a direct detection platform using Fc-cored polyamidiamine dendrimers (Fc-PAMAM) deposited on Au electrode (Fig. 4d).…”

Label-Free Immunosensor Based on Liquid Crystal and Gold Nanoparticles for Cardiac Troponin I Detection

“…The unique electro-optical properties of liquid crystal are promising toward the development of a simple and reliable sensing platforms for the quantification of biomolecules. For the most part, the optical properties of LC are exploited to detect molecules [ 33 , 35 , 36 , 37 , 38 ] and in a number of biosensing systems that employ electrochemical detection [ 39 , 40 , 41 ].…”