Temperature-compensated reflective microfiber biosensor with molecularly imprinted polymer-enhanced specificity for trace lysozyme concentration detection

We present a novel temperature‐compensated reflective optical probe‐based molecularly imprinted polymer (MIP) optical fiber biosensor of functionalized gold nanoparticles (AuNPs) for the specific detection of trace lysozyme. The MIP film is encapsulated on the surface of L‐cysteine‐modified AuNPs by surface imprinting, and the resulting functionalized AuNPs are bound to the optical fiber surface using self‐assembly of polyaniline (PANI), which, after using an elution solution, formed binding sites specific for lysozyme. The strong evanescent field of the reflective optical probe sensor sensed the small refractive index (RI) changes induced by specific binding of MIPs to lysozyme, which are ultimately converted into macroscopic wavelengths in the reflection spectrum of the sensor. The experimental results show that the functionalized AuNPs‐MIP sensor is capable of detecting lysozyme ultra‐sensitively in a concentration range of 0.5 ng/ml to 0.5 mg/ml in a background of phosphate buffer solution (PBS), with a sensitivity of 0.917 nm/(ng/ml) and a limit of detection (LOD) of 0.294 ng/ml. Meanwhile, in the real detection environments represented by egg white, artificial urine and wine, the good responses are also obtained with LOD of 0.414 ng/ml, 0.418 ng/ml and 0.403 ng/ml, respectively. This strategy provides a valuable method for lysozyme detection sensors, and also offers the possibility of future applications in the industries of healthcare, food and so on.