Electrochemical determination of malondialdehyde biomarker in exhaled breath condensate using poly arginine functionalized by graphene quantum dots and chitosan

Lipid peroxidation is a prominent manifestation of free radical activity in biological systems, and it is involved in the development of different diseases such as cancer or cardiovascular and liver diseases. Malondialdehyde (MDA) is globally recognized as a scientifically accepted biomarker of oxidative stress. Due to the significance of MDA as a marker of lipid peroxidation and because of its elevations in various diseases, the assessment of MDA with new and reliable assays, the development of a fast, sensitive, and selective method to detect MDA with simple instruments is necessary. This study used the electro polymerization of a low toxic and biocompatible polymer with entitle poly arginine-graphene quantum dots-chitosan (PARG-GQDs-CS) as a novel strategy for surface modification of glassy carbon (GC) surface and preparation a new interface for measurement of MDA in human exhaled breath condensate (EBC). Nanocomposite PARG/CS/GQDs the method of precipitation out of place (ex situ) on the electrode surface was prepared. To verify sequestration nanobiopolymer synthesized Scanning electron microscope images (SEM) were recorded. To identify and study the behavior of malondialdehyde electrochemical methods such as cyclic voltammetry and differential pulse voltammetry were used. The scanning electron microscopy (SEM) images indicated immobilization of uniformly CS and GQDs onto PARG film. The modified electrode appeared as an effective electro activity for detection of MDA. Under the optimized analysis conditions and physiological pH, the prepared sensor showed one oxidation processes for MDA at potentials about 1 V vs. Ag/AgCl with a low limit of quantification (LLOQ) 5.94 nM. The Glassy carbon electrod modified by poly-arginine/chitosan/graphene quantum dots, has good electrical activity for Electro-oxidation malondialdehyde that could be due to synergistic effect poly-arginine, graphene quantum dots and chitosan to create many active sites for this purpose.