Abnormal human immunoglobulin G (IgG) may induce the risk of immune system disorder, infectious diseases, tumors and so on. However, the current detection methods exhibit low sensitivity, which limits their practical application. In this work, an SPR optical fiber sensor (SPR-OFS) with high sensitivity is designed for label-free detection of human IgG. It is fabricated using a heterostructure optical fiber coated with Au film/AuNPs and the Ti3C2Tx MXene biofunctionalized with goat anti-human IgG by polydopamine (PDA). In the experiment, the optimal thickness of the Ti3C2Tx MXene was explored and determined to be about 93 nm by comprehensively considering the refractive index (RI) sensitivity and spectral bandwidth of the SPR sensor. When the largest figure of merit (FOM) is calculated to be 17.8279 RIU−1, its RI sensitivity was ultimately found to be 2804.5 nm per RIU. The SPR-OFS was employed to detect human IgG within the concentration range of 0–30 μg mL−1 and its sensitivity is demonstrated to be 1.7046 nm (μg mL−1)−1. The SPR-OFS was also proved to have excellent linearity, specificity and stability. The proposed sensor offers outstanding performance with simple fabrication, providing a cutting-edge bioanalytical platform with potential applications in clinical diagnosis.
Ling-Xin Kong,Yan-Xin Zhang,Wei-Gang Zhang,Yun-Shan Zhang,Tie-Yi Yan,Peng-Cheng Geng,Biao Wang
Lab-on-tip technology opens a new door for optical fiber surface plasmon resonance (SPR) sensors. In this paper, we first demonstrate an ultra-compact reflective SPR microtip probe on the flat fiber end in experiment, which has a length of tens of microns and a diameter of several microns. Simulations and experiments show that this new fiber SPR microtip probe coated with a nano-goldfilm has excellent refractive index (RI) sensing characteristic and great potential for biochemical detection at single cell level. Based on the high RI sensitivity, a bio-probe assembled with Chitosan/Polysodium Styrene Sulfonate (Cs/PSS) nano-polyelectrolyte film and the sheep anti-human IgG-HRP is prepared to recognize human IgG specifically. Due to the high surface sensitivity, the SPR microtip probe exhibits an ultra-low detection limit for human IgG. Due to the high bulk sensitivity and high thermo-optical coefficient (TOC) of polydimethylsiloxane (PDMS), a reference temperature probe based on SPR microtip is proposed, which is used to compensate for the temperature cross-sensitivity of the bio-probe. This new SPR microtip probe can be used not only in optical fiber sensor, but also in Tip-Enhanced Near-Field Raman Microscopy and Scanning Near-Field Optical Microscope.
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