Plasmonic Point-of-Care Device for Sepsis Biomarker Detection

The need for point-of-care (POC) devices for detecting the onset of sepsis has become critical since sepsis is one of the most prevalent causes of deaths worldwide in non-coronary intensive care units at the hospitals. Every one hour delay in exercising proper medication can lead to an exponential rise in mortality. Motivated by this, we propose a POC device for sepsis biomarker detection, which will complement traditional blood culture-based techniques for easy and quicker diagnosis and monitoring of sepsis state. The working principle of the device is based on amalgamation of surface plasmon resonance (SPR) technology with microfluidics. The sensing chip consists of a gold and graphene oxide coated patterned array of periodic nanoposts to detect target biomarker molecules in a limited sample volume. The nanoposts are functionalized with specific receptor molecules that serve as a nanostructured plasmonic crystal for SPR-based bio-sensing via the excitation of surface plasmon polaritons. The sensitivity of the device to one of the known sepsis biomarkers, Pro-calcitonin (PCT), was found to be 0.0643 a.u./ pg.ml
^-1
at lower concentration and 0.0224 a.u./ pg.ml
^-1
at higher concentration, and a LOD of 1.22 pg.ml
^-1
. The sensor chip provides an opportunity to dynamically measure antigen-antibody bindings and the soft-lithography based sensor manufacturing technology provides high reproducibility of the sensor response to PCT molecules even at a picomolar level. The microfluidics-based platform provides potential for future integration with other microfluidic devices viz. plasma separator for separating the PCT-sized molecules to enable blood sample measurements.