The resistive switching (RS) mechanism is resulted from the formation and dissolution of a conductive filament due to the electrochemical redox-reactions and can be identified with a pinched hysteresis loop on the I–V characteristic curve. In this work, the RS behaviour was demonstrated using a screen-printed electrode (SPE) and was utilized for creatinine sensing application. The working electrode (WE) of the SPE has been modified with a novel small organic molecule, 1,4-bis[2-(5-thiophene-2-yl)-1-benzothiopene]-2,5-dioctyloxybenzene (BOBzBT2). Its stability at room temperature and the presence of thiophene monomers were exploited to facilitate the cation transport and thus, affecting the high resistive state (HRS) and low resistive state (LRS) of the electrochemical cell. The sensor works based on the interference imposed by the interaction between the creatinine molecule and the radical cation of BOBzBT2 to the conductive filament during the Cyclic Voltammetry (CV) measurement. Different concentrations of BOBzBT2 dilution were evaluated using various concentrations of non-clinical creatinine samples to identify the optimised setup of the sensor. Enhanced sensitivity of the sensor was observed at a high concentration of BOBzBT2 over creatinine concentration between 0.4 and 1.6 mg dL−1—corresponding to the normal range of a healthy individual.

The sandwiched material-analyte layer in the surface plasmon resonance (SPR)-Otto configuration emulates an optical cavity and, coupled with large optical nonlinearity material, the rate of light escaping from the system is reduced, allowing the formation of a strong coupling regime. Here, we report an organic pentamer SPR sensor using the Otto configuration to induce a strong coupling regime for creatinine detection. Prior to that, the SPR sensor chip was modified with an organic pentamer, 1,4-bis[2-(5-thiophene-2-yl)-1-benzothiopene]-2,5-dioctyloxybenzene (BOBzBT2). To improve the experimental calibration curve, a normalisation approach based on the strong coupling-induced second dip was also developed. By using this procedure, the performance of the sensor improved to 0.11 mg/dL and 0.36 mg/dL for the detection and quantification limits, respectively.

The synthesis of novel material 1,4‐bis[2‐(5‐thiophen‐2‐yl)‐1‐benzothiophene]‐2,5‐dioctyloxybenzene pentamer (BOBzBT2) was carried out via Williamson etherification, bromination, and Suzuki coupling. Functionalization was carried out via the incorporation of dioctyloxy‐substituents on phenylene moiety to improve its solubility. The elongation of the π‐conjugation backbone was carried out through the addition of benzo[b]thiophene rings of BOBzBT2 to accelerate cation radicals′ formation. In FTIR, the disappearance of the stretching peak of υ(CBr) at 657 cm−1 confirms the coupling of benzo[b]thiophene rings end‐capped the BOBzBT2 UV‐visible shows the appearance of two broad bands at 343 nm and 422 nm, that related to π‐π* transition between thiophene and bithiophene groups with 2,5‐bis(dioctyloxy)benzene moiety in the π‐conjugated backbone, respectively. DSC shows that the BOBzBT2 is a high purity compound. A gradual relaxation occurred between BOBzBT2 with creatinine as observed in UV‐visible analysis. It is expected that the BOBzBT2 sensed creatinine via NH−S and NH−O hydrogen bonding interactions.

No abstract

No abstract