Scorpion-Inspired, Hydrophobic, Highly Sensitive, and Paper-Based Magnetoelastic Biosensor for C-Reactive Protein Detection

C-reactive protein (CRP) in human blood has crucial clinical significance as a valid biomarker for acute infection or inflammation. There is an increasing demand for paper-based magnetoelastic (ME) biosensors with water repellency and convenience for CRP detection, currently. Herein, we have developed a paper-based ME biosensor with hydrophobic, highly sensitive, low-cost, and environmentally friendly methods. Based on inspiration from the scorpion, the V-shaped grooves were introduced into the biosensor to improve sensitivity. Photo paper (P-paper) functionalized with CoFe2O4 and MWCNTs was selected as the substrate for the sensor, while PDMS was used as a sealing layer to achieve the hydrophobicity of the sensor. AuNPs/PDMS was used to provide the biomodification site for CRP antibody binding. Due to the ME effect of CoFe2O4 and the electrical conductivity of MWCNTs, surface stress generated by specific binding of CRP antigen and CRP antibody is converted into electrical and magnetic signals. The results show that the limit of detection (LOD) was 100 pg/ml in the linear range from 100 pg/ml to 1000 ng/ml. In addition, the ME biosensor displays an outstanding performance in stability and specificity experiments.