Differential Refractometric Biosensor for Reliable Human IgG Detection: Proof of Concept

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Abstract
A new sensing platform based on long-period fiber gratings (LPFGs) for direct, fast, and selective detection of human immunoglobulin G (IgG; Mw = 150 KDa) was developed and characterized. The transducer’s high selectivity is based on the specific interaction of a molecularly imprinted polymer (MIPs) design for IgG detection. The sensing scheme is based on differential refractometric measurements, including a correction system based on a non-imprinted polymer (NIP)-coated LPFG, allowing reliable and more sensitive measurements, improving the rejection of false positives in around 30%. The molecular imprinted binding sites were performed on the surface of a LPFG with a sensitivity of about 130 nm/RIU and a FOM of 16 RIU−1. The low-cost and easy to build device was tested in a working range from 1 to 100 nmol/L, revealing a limit of detection (LOD) and a sensitivity of 0.25 nmol/L (0.037 µg/mL) and 0.057 nm.L/nmol, respectively. The sensor also successfully differentiates the target analyte from the other abundant elements that are present in the human blood plasma.
Funding Information
  • National Funds through the Portuguese funding agency, FCT—Fundação para a Ciência e Tecnologia (PTDC/EEI-EEE/4832/2021, UIDB/50014/2020)
  • Fundação para a Ciência e a Tecnologia (PTDC/EEI-EEE/4832/2021, UIDB/50014/2020)

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