The MMTWENTY was designed as a portable electrochemical device specific for uric acid detection using mini protein mimicking native uricase (mp20) encapsulated onto microporous ZIF-8 as a bioreceptor fabricated onto reduced graphene oxide/screen-printed carbon electrode (rGO/SPCE) surface as a transducer, which eventually convert the biorecognition process into a measurable signal and then displayed  on the device screen.

There are several existing analytical methods that are well established, such as high-performance liquid chromatography (HPLC), spectrophotometric, electrochemical and flow-injection analysis. However, some of the techniques are too sophisticated, tedious in sample preparation, expensive and time-consuming, which limits their use in clinical laboratories. Electrochemical technique is one of the best approaches that could be used to minimize the limitations, and its simplicity, fast and accurate response make it widely explored for the development of point-of-care tests.

 

The utilization of native enzyme uricase for uric acid electrochemical biosensor construction is preferable as the biorecognition element is able to provide specific binding sites and recognize the targeted molecule. Commercially available uric acid POCTs also depend on the catalytic activity of immobilized uricase on electrodes. However, there are two major drawbacks to using native enzymes in the system: (i) the high cost of larger-scale production and (ii) non-stability under inappropriate conditions such as high temperature, unfavourable pH, and organic solvents, which cause the enzyme denaturation. For instance, EasyTouch-GU, UASure, BeneCheck TM Plus and HumaSens-Plus are several point of care tests (POCTs) products available in the market for monitoring purpose. However, several of the products were discovered to be least user-friendly with lack of accuracy as several attempts are needed for better precision.

 

Thus, to address the challenges, a mini protein (mp20) mimicking uricase is used as a replacement for the native structure. It is a small molecule of 20 amino acids that can interact with uric acid, with similar spectroscopic properties to its native counterpart, and is more stable, selective and economical to produce and use. The stability of mini protein 20 can be improved by encapsulating the mp20 within a metal organic framework (MOF). Due to its porous materials and high loading capacity, MOF is an attractive support for enzymes. MOF can protect the enzyme from denaturation and improve the enzymatic activity and stability.

 

Advantages 

 

• The MMTWENTY portable device, which adapts an electrochemical method for uric acid detection, is able to offer a simple, fast, sensitive, and non-tedious approach in comparison with conventional techniques.

 

• The electrode was constructed via easy fabrication using mini protein mimicking uricase (mp20) as a bioreceptor instead of native uricase, as it is more stable and cost-effective to use with similar specificity towards uric acid.

 

• The use of mini protein (mp20) encapsulated into high porosity ZIF-8 as bioreceptor could offer better stability which could prolonged its shelf life.

 

• The MMTWENTY portable device, which is built for sensitive detection of a low range of uric acid, could serve as an early monitoring device.

 

• The fabricated electrode which specific towards targeted uric acid can be reproduced at lower cos

 

Dr Shahrul Ainliah Alang Ahmad
Faculty of Science
Emel  : ainliah@upm.edu.my

 

Date of Input: 30/06/2022 | Updated: 30/06/2022 | asrizam