Surface modified pencil graphite electrodes (PGES) as micro/nanoplatforms to test/analysis of drugs/addictive materials

In recent years, drugs/addictive substances cause significant health and they can be characterized as substances when taken into the body outside of health applications, have different neurological, physiological and behavioral effects in the organism and lead to significant problems that lead to death when taken above certain doses. Legal regulations have been developed regarding these substances, whose possession in drug use, distribution and similar applications is considered as a crime. Some immunochemical (Elisa, EMIT, CEDIA, FPIA) and chromatographic techniques (GC-MS, LC-MS/MS) that give extremely precise results today in the test/analysis and screening processes are available, but the need for portable systems that provide fast and accurate results, especially in field tests and scans, is growing every day. In recent years, among these systems especially electrochemical based biosensors are most favorable and they can measure electrochemical changes in the presence of targeted drugs/similar substances based on different principles (such as voltametric, amperometric or conductometric). These are currently noteworthy as systems that are portable and can perform field measurements in a very short time. The scope of this study is surface modification of pencil graphite electrodes (PGEs) in an electrochemical based biosensor. In this context, PGEs were attempted to increase the surface areas/measurement capacities by creating micro/nanoscale wells or hills. Micro/nano wells are formed by the breath figure technique with a thin polymeric film and micro/nano hills are formed by precipitation of hydroxyapatite crystals on PGEs surfaces. Then, PGEs were treated with copper sulfate, allowing the micro/nano platforms to be decorated with copper oxides in basic conditions with NaOH. In the application stage of the study, a model drug was considered, and solutions of this substance were prepared in different concentrations by using phosphate buffer solution and a calibration curve was obtained with the modified PGEs. In the effectiveness tests of the platforms, quantitative measurements were made by using the same sample which concentration is unknown. The results were evaluated, and it was understood that the platform consisting of micro/nano hills in particular was promising, and it was decided to continue the work with real samples by using this method.