Calcium selective optical sensor based on calmodulin functionalized porous silicon

In this work an optical calcium sensor is fabricated using calmodulin surface functionalized macro-porous silicon. Porous silicon is prepared by electro-chemical etching process on silicon wafers, which were further calmodulin surface functionalized for effective calcium binding. Porous silicon provides many fold increase in surface area to volume ratio for absorption, and calmodulin provides effective calcium binding sites. Investigating with different bi-valent and mono-valent cations, the fabricated structure shows effective selectivity and multi-parametric optical response for calcium ions. Several Optical parameters such as reflectance, scattering loss and absorption loss were measured for calcium and other bi-valent and mono-valent cations at physiologically relevant concentrations, the sensor showed great discrimination towards calcium ion. Calcium being the most abundant cation present in the human body plays a significant role in cellular signalling pathways. Moreover Calcium is abundant in drinking water and is important for ecosystem maintenance. The sensor fabricated in this work finds application in calcium sensing in drinking water samples as well as in serum. Thus the sensor provides a highly sensitive, easy to use and cost-effective alternative for calcium detection and sensing.

Automated summary

An optical calcium sensor was fabricated using calmodulin surface-functionalized macro-porous silicon, showing effective selectivity and multi-parametric optical response for calcium ions. The sensor provides a highly sensitive, easy to use and cost-effective alternative for calcium detection and sensing in drinking water samples and serum.