Spider silk has excellent properties such as elasticity, tensile strength, biocompatibility, and biodegradability. Furthermore, since it transmits light like an optical fiber, its application to various optical components used in the biomedical field is being researched.

A research team at Taiwan's Yang Ming Jiaotong University has developed a biosensor that monitors sugar concentrations from changes in the refractive index of solutions, using the properties of spider silk to transmit light. New optical sensors could be useful for measuring blood sugar levels and other biochemical analyses. The results of the study are published on August 2, 2022 in the journal Biomedical Optics Express.

Blood glucose measurement is important for diabetics, and it is recommended to self-monitor blood glucose before and after meals. However, conventional blood glucose meters are invasive and uncomfortable for the patient. There is also the problem of high cost.

The research team created an optical fiber with a diameter of just 100 μm by wrapping the silk of the Pleurotus nephila in a biocompatible photocurable resin. In order to further enhance the sensing ability, it is coated with gold. By dipping one end of the spider silk fiber into a liquid sample and connecting the other end to a measuring instrument, the refractive index of the solution can be used to determine the type and concentration of sugar in the sample.

When a solution containing glucose, sucrose, and fructose was measured at room temperature using a spider silk fiber optic sugar sensor, we were able to actually identify the type of sugar and measure its concentration. The sugar concentration used in this experiment covers the sugar concentration in human blood. In addition, the sensor has a response time of 0.1 milliseconds, enabling real-time measurements.

Not only is the sensor highly sensitive, biocompatible, reusable and cost-effective, it is so small that it can be placed in hard-to-reach areas such as the brain and heart. Application to implantable medical devices is also expected.

The research team is already developing software for point-of-care measurements using mobile devices. They also want to extend the capabilities to measure various other blood biochemicals, such as lactose and fat.