Sepsis is a severe inflammatory disorder caused by microorganisms and the human body secretion of cytokines that leads to organ dysregulation or dysfunction. C-reactive protein (CRP) is an acute-phase protein, which is a signature compound of cardiovascular disease and related infection biomarker. The normal level of CRP in a healthy person is 2 mg mL^-¹, while for a sepsis patient, it increases more than 1000 times. The extremely low concentration of CRP detection in human serum samples is challenging. The presence of cells, proteins, and other electrochemical bioactive molecules in a clinical sample influences the sensor probe and detriments the detection limit and sensitivity. Therefore, the major issues for the electrochemical CRP sensing in the serum sample include limited sensitivity, electrode fouling effect, redox couple current intensity reading, and antigen incubation time. To overcome these issues, we developed the conductive Ti₃C₂T_x MXene/CRP antibody (ab1)/bovine serum albumin (BSA) composite electrode (Ab₁/BSA/Ti₃C₂T_x). The design of the signal probe was as follows: porous redox active linker functionalized UiO metal-organic framework (MOF)/Ti₃C₂T_x was prepared, and its surface was grafted by secondary CRP Ab₂ like Ti₃C₂T_x/UiO-N=N-Φ(OH)₂/Ab₂. The UiO-N=N-Φ(OH)₂/Ti₃C₂T_x composite conferred the high surface area to anchor a high concentration of Ab₂ which aids CRP detection in a wide concentration range. The conductive MXene entrapped MOF containing redox couple allowed to enhance current intensity providing high sensitivity. The functional groups present on the surface of MOF acted as antifouling agents. The Ab₁ modified electrode incubated in the CRP serum sample and allowed to secondary Ab₂ signal probe the gained final electrode Ti₃C₂T_x/UiO-N=N-Φ(OH)₂/Ab₂/CRP/Ab₁/BSA/Ti₃C₂T_xunderwent the cyclic voltammetry study for the CRP quantification. CRP detection in serum sample studies indicates the possibility of Ti₃C₂T_x/UiO-N=N-Φ(OH)₂/Ab₂/CRP/Ab₁/BSA/Ti₃C₂T_xreal-time biosensing application.

Katarzyna Krukiewicz

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