**6. Internet of things (IoT)-enabled enzyme embossed biosensor**

IoT -Enabled Enzyme Embossed Biosensor is a novel approach to detect vitamin D in clinical samples. The biosensor is a combination of enzyme immobilization and IoT technology that allows real-time monitoring of the sample without the need for manual intervention [24].

The biosensor is composed of a glass substrate coated with gold nanoparticles and decorated with graphene oxide sheets. The immobilization of enzymes, such as alkaline phosphatase (ALP) and glucose oxidase (GOx), on the surface of the graphene oxide sheets is carried out using a dip coating method. The ALP enzyme is used to convert 25-hydroxyvitamin D3 (25(OH)D3) to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), while the GOx enzyme is used to produce hydrogen peroxide (H2O2) in the presence of 1,25(OH)2D3. The H2O2 produced is then detected using IoT technology, and the amount of vitamin D present in the sample is calculated based on the concentration of H2O2 produced [24].

In a study by Ghosh and Koley [86], the IoT-enabled enzyme embossed biosensor was able to detect vitamin D with high sensitivity and selectivity. The biosensor showed a linear range of detection from 0.05 to 200 ng/mL, with a limit of detection of 0.02 ng/ mL. The authors also noted that the biosensor had good reproducibility and stability, with a relative standard deviation of less than 5% and a shelf life of up to 3 months.

The use of IoT technology in the biosensor allows for real-time monitoring of the sample without the need for manual intervention, making it a potential candidate for automated vitamin D determination in clinical settings. The biosensor can be easily integrated with IoT-enabled devices, such as smartphones or cloud-based systems, allowing remote access to the data generated by the biosensor.

In other studies, by Kishnani et al. [87] and Faham et al. [88], the IoT-enabled biosensor was used to detect vitamin D in human serum samples. The biosensor showed a linear range of detection from 0.01 to 100 ng/mL, with a limit of detection of 0.006 ng/mL. The biosensor also demonstrated high selectivity for vitamin D, with minimal interference from other substances present in the serum samples.

The authors noted that the biosensor had several advantages over conventional methods of vitamin D determination, including its high sensitivity and selectivity, low cost, and ease of use. The use of IoT technology in the biosensor also allowed for remote monitoring of the sample, making it a potential candidate for point-of-care testing in resource-limited settings.

In a review article [24, 87], the authors discussed the potential of IoT-enabled biosensors for the determination of vitamin D and other biomolecules. The authors highlighted the advantages of these biosensors, including their high sensitivity, selectivity, and real-time monitoring capabilities. The authors also noted that the use of IoT technology could improve the accessibility and affordability of vitamin D determination in resource-limited settings.

The feature and performance values of the described detection system are as follows. The linear range of detection spans from 0.01 to 200 ng/mL, indicating the

### *Vitamin D Detection Using Electrochemical Biosensors: A Comprehensive Overview DOI: http://dx.doi.org/10.5772/intechopen.112212*

concentration range within which the system can accurately measure. The limit of detection, ranging from 0.002 to 0.006 ng/mL, highlights the system's ability to detect even very low concentrations of the target substance. The sensitivity and selectivity of the system are both high, meaning it can accurately and specifically identify the target compound. The reproducibility of the system is good, with a relative standard deviation below 5%, indicating consistent results across multiple measurements. The stability of the system is also good, with a shelf life of up to 3 months. The advantages of this detection system include its high sensitivity and selectivity, real-time monitoring capabilities, low cost, and ease of use. These features make it suitable for a variety of applications, such as automated vitamin D determination in clinical settings and point-of-care testing in resource-limited settings. Overall, the IoT-enabled enzyme embossed biosensor shows great potential for the determination of vitamin D in clinical samples. The biosensor offers high sensitivity, selectivity, and real-time monitoring capabilities, making it a promising candidate for automated vitamin D determination in clinical settings.
