Three-Dimensional Printed Flexible Magnetoelastic Biosensor for C-Reactive Protein Detection Based on Patterned PDMS/MnFe2O4 Film

For the first time, a flexible magnetoelastic (ME) biosensor with grid microstructure deposited on the PDMS/MnFe2O4 film is developed for the detection of C-reactive protein (CRP), a biomarker of cardiovascular diseases (CVDs) and inflammations. The patterning of flexible ME films was realized by fabricating mesh molds employing Three-Dimensional printing technology to enhance the sensitivity of the film to stress. CRP antibodies, which were specifically recognized to CRP, were modified on the surface of AuNPs assembled PDMS/MnFe2O4 film via gold-sulfur affinity. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and atomic force microscope (AFM) characterization proved that the biosensor successfully realized the surface biological functionalization modification and effectively recognized CRP. Due to the excellent magneto-electric properties of MnFe2O4 nanoparticles and the superior flexibility of PDMS, the flexible ME biosensor transforms the surface stress signal induced by the specific binding of CRP and antibody modified on the film into the electromagnetic signal. The flexible ME biosensor showed a wide linear range (10 ng/mL–
$100 ~\mu \text{g}$
/mL) and low detection limit (10 ng/mL), which is significantly lower than the minimal warning diagnosis limit of CVD. Some possible interfering substances were also measured for comparison, demonstrating that the biosensor possessed good selectivity. This flexible ME biosensor is applicable as an inexpensive, highly sensitive, easy-to-use, and disposable method for CRP detection, providing an attractive protocol for early CVD diagnosis and postoperative monitoring.