TECHNICAL AREA

The invention relates to the innovation in the part of the electronic measuring devicesused for routine control of blood sugar in contact with the blood sample.

PRIOR ART

In applications where the glucose sensor has been used for years, products in different designs have been introduced to the market by following similar methods. There are patents related to these products, and in addition to this, a large number ofpublications have been made.

In the current art, glucose sensor fabrication is based on the use of enzymes to achieve high selectivity and detection performance. On the other hand, using the biological compound in glucose sensors reveals some disadvantages, such as complex enzyme immobilization process and high cost, low stability of the enzyme layer, and synchronous short shelf life. All of these challenges hinder the further development of enzymatic glucose sensors.

BRIEF DESCRIPTION OF THE INVENTION

To address the shortcomings mentioned above, the detection of non- enzymatic blood glucose has been a focus in the last few years, which relies on the use of catalytically active nanomaterials instead of enzymes for glucose redox reactions. Researchers try different methods to make the most of the catalytic properties of nanomaterials.

In our invention, which was presented within the scope of our application, a unique lattice structure nanomaterial was obtained by the electrospinning technique. Thus, more stable and sensitive glucose sensors can be produced.

As diabetic patients who constantly use enzymatic-based measuring sticks know very well, significant errors occur in the values measured with these products after a certain period. It is recommended to obtain a new one immediately as a solution. With our invention, the frequency of such problems is decreasing. LIST OF FIGURES

Figure 1. SEM Image of Lattice Shaped Nanofibers Produced

DETAILED DESCRIPTION OF THE INVENTION

Our invention is based on the principle of obtaining palladium (Pd), silver (Ag), and grapheme oxide (GO) nanomaterials in the form of a lattice in specified proportions and with a new method. Many custom-made noble metal and metal oxide nanostructures, such as Pd, exhibit excellent electrocatalytic sensing properties against glucose and other analytes. Pd nanoparticles (NPs) are of great interest due to their superior chemical and electrochemical properties, including good chemical stability, excellent electrical conductivity, and remarkable electrocatalytic performance. However, agglomeration may occur during the synthesis of Pd NPs, affecting reactivity, stability, recyclability, and especially detection performance. To overcome these shortcomings, the fabrication of nanoalloys based on Pd metal with some transition metal is an effective strategy due to the increased synergistic effect due to their strong interaction. In addition, alloy formation results in defects within the structure that often affect the electronic cloud, hence the formation of increased electro-active sites for electron transfer.

Ag ⁺ ion has strong antibacterial properties and shows excellent and broadspectrum antibacterial activity against various bacterial propagules, bacterial spores, viruses, fungi, and other microorganisms. In addition, it has been reported that composite materials doped with small amounts of Ag ⁺ ions are not toxic to the human body. As the other form of silver, Ag NPs exhibit excellent antibacterial and electrical conductivity, and have a large specific surface area and intense surface activity. Ag NPs have also been chosen to improve nanofibers’ antibacterial properties and conductivity.

The unique properties of carbon-based materials enable the determination of many molecules of high biological importance using electrochemical methods with high sensitivity, fast, and reliability. Graphene is an atomic-level thin layer formed due to the sp2 hybridization of carbon atoms and the hexagonal arrangement in two dimensions. This atomic arrangement of graphene provides an unmatched high electrical conductivity, mechanical strength, and very high physical surface area. GO is substantially graphene with some functional groups on its surface. GO is a proper supporting element for ceramic composites due to its superior mechanical properties. Its unique electrical and thermal properties make it an exciting additive in producing multifunctional ceramics with vast application areas. Graphene-supported ceramics have great potential due to the contribution of graphene.

For this purpose, the electrospinning method was used. The electrospinning method provides an ideal sensor material structure by attaching the composite material to a fiber with a diameter of several hundred nanometers and forming a three-dimensional lattice structure on the collector that these fibers reach by rotating. In a single process, this method converts ionized metals (Ag ⁺ and Pd ²⁺ ) into uncharged nanoparticles. The properties of nanofibers produced by the electrospinning method are affected by parameters such as concentration, the distance between the syringe tip and collector, and flow rate. The production steps of our invention are as follows:

- First, a 10% water solution of polyvinyl alcohol (PVA), the support polymer, was prepared homogeneously. PVA is a binder material with high biocompatibility, water-soluble, and easily removed from the environment due to calcination. In addition, it has been preferred because its supply and price are competitive compared to its counterparts. The optimum concentration of the solution of PVA prepared in water was chosen as 10% by mass since it complies with criteria such as homogeneity, viscosity, and the rapid evaporation of the solvent during the electrospinning stage.

- 5 mmol AgNOs (0.8494 g) and PdCh (0.8867 g) as solid powder were added into 10 mL of 2 mg/mL GO (graphenoxide) dispersion solution and mixed well at 60°C.

- Then, this mixture was added to 10% PVA, preheated to 60°C, and dissolved in a magnetic stirrer by mixing it well. Thus, an electrospinning solution containing all the components for our composite material was prepared.

- The amount of GO was adjusted at 1% in 10% PVA. Due to its chemical properties, GO has a strong attraction between its layers and significantly affects the physical properties of the solution in which it is found. It is necessary to choose a concentration that gives the required contribution and does not interfere with the electrospinning process.

In this mixture, PVA acts as a support polymer and helps the nanoparticles to be arranged in the lattice structure. Composite materials in the PVA basic solution medium become filaments with a nanometers diameter due to electrospinning. The accumulation of the filaments in this structure in a multi-layered network will ensure the formation of a three-dimensional lattice structure. As a result of the calcination process, the organic component, namely PVA, is removed from the nanofiber textile material obtained in this way, and a material with a three- dimensional lattice structure is obtained from the ceramic material.

During the solution preparation stage, the details of the method in which we obtained nanofibers in the most appropriate size and properties as a result of the trials carried out to obtain nanofibers from the solution we prepared by electrospinning method are given below;

- First, 5 mL of polymer solution is drawn into the syringe and placed in the syringe pump,

- A high voltage of 11.5 kV from the power supply is applied to the syringe tip through the high voltage power supply,

- The solution flow rate is set at 0.3 mL per hour from the syringe pump, and the electrospinning process is initiated,

- The polymer from the syringe is formed into nanofibers by the electric field effect created by the high voltage applied.

By heat treatment of nanofibers, which are obtained in the form of textiles and consisting of a mixture of PVA/GO/Ag/Pd, in an oven at 400°C, ceramic sensor material is obtained in powder form and with a lattice structure. This process removes PVA, which is also used as a support polymer, from the environment. The sensor material is then dispersed as homogeneously as possible in the dimethylformamide solvent and dropped onto the screen-printed electrode surface with the help of a dropper. Dimethylformamide is a suitable dispersion solvent due to its physical and chemical properties. In addition to being suitable for preparing a homogeneous dispersion, it is preferred because it is easily removed from the environment during the drying phase. After drying, the glucose sensor is ready.

The sensor we obtained enables glucose to be detected more efficiently, which is very difficult to detect under normal conditions and with a conventional electrode. Pd, Ag, and GO materials in the sensor material we produce both facilitate and accelerate the oxidation reaction of glucose instead of the enzyme that functions as a catalyst in glucose sensors, which are available in the market and are widely used. Thus, a signal is obtained to detect the presence and concentration of glucose.