Towards sensitive label-free immunosensing by means of turn-around point long period fiber gratings.
Long period fiber gratings have been effectively used in the field of biochemical sensing since a few years. Compared to other well-known label-free optical approaches, long period gratings (LPGs) take advantage of the typical peculiarity of optical fibers. Coupling the propagating core mode with a high-order cladding mode near its turn-around point (TAP) was the strategy adopted to achieve good performances without additional coatings, except for the sensing and selective biolayer deposited on the fiber. Both the modeling and manufacturing of TAP LPGs were discussed. After the functionalization of the fiber surface with the deposition of a Eudragit L100 copolymer layer followed by immunoglobulin G (IgG) covalent immobilization, an IgG/anti-IgG bioassay was implemented along the grating region and the kinetics of antibody/antigen interaction was analyzed. A quantitative comparison between a TAP LPG and a non-TAP LPG was carried out to highlight the improvement of the proposed immunosensor. The real effectiveness and feasibility of an LPG-based biosensor were demonstrated by using a complex matrix consisting of human serum, which also confirmed the specificity of the assay, and a limit of detection of 70 μg L(-1) (460 pM) was achieved.
Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
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Chiavaioli
Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research, 196 Raja S C Mullick Road, Kolkata 700032, India. Electronic address: palas@cgcri.res.in.
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Biswas
Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy. Electronic address: c.trono@ifac.cnr.it.
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Trono
Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research, 196 Raja S C Mullick Road, Kolkata 700032, India.
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Bandyopadhyay
Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
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Giannetti
Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
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Tombelli
Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research, 196 Raja S C Mullick Road, Kolkata 700032, India.
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Basumallick
Central Glass and Ceramic Research Institute, Council of Scientific and Industrial Research, 196 Raja S C Mullick Road, Kolkata 700032, India.
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Dasgupta
Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
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Baldini
D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007118:Immunoassay / Q000295:instrumentation*; D007074:Immunoglobulin G / Q000032:analysis* / Q000276:immunology*; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling
D007074:Immunoglobulin G
Immunosensor; Label-free; Long period grating; Optical fiber biosensor; Serum; Turn-around point