A peanut type optical fiber biosensor based on SPR effect for chloramphenicol measurement

Abstract

A peanut-shaped fiber optic biosensor for chloramphenicol measurement based on the SPR effect includes a broadband light source (SLED), a sensing structure, and an OSA (Optical Spectrum Analysis System). The sensing structure includes a single-mode fiber, a peanut-shaped fiber, a Bragg fiber grating (FBG), and a surface functional modification region. The surface functional modification region includes an APTES-modified region, a gold film, and a CAP-BSA coupling region. This invention utilizes a peanut-shaped structure to couple more light from the single-mode fiber core into the cladding, enhancing the SPR effect and improving sensitivity. Specific detection of chloramphenicol is achieved through the CAP-BSA coupling region on the fiber surface. Temperature testing is performed using a cascaded Bragg fiber grating to establish a temperature-chloramphenicol concentration sensitivity coefficient matrix, reducing temperature interference with chloramphenicol concentration detection, resolving cross-sensitivity issues, and improving accuracy. This invention features a compact structure, simple fabrication, high accuracy, and high sensitivity.

Description

Technical Field

[0001] This utility model relates to a fiber optic biosensor, and more particularly to a peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement, belonging to the field of fiber optic sensor technology. Background Technology

[0002] In the field of drug residue detection, chloramphenicol, as a broad-spectrum antibiotic, is strictly limited in food due to its potential toxic side effects. Traditional detection methods such as gas chromatography (GC) and mass spectrometry (MS), while sensitive, have significant limitations. GC requires derivatization steps such as silanization to increase the volatility of chloramphenicol, but derivatization reactions are easily affected by environmental factors, and derivatization byproducts may interfere with the detection results. While GC-MS combines high sensitivity and structure confirmation capabilities, it also relies on complex sample preparation (such as liquid-liquid extraction and solid-phase extraction), making it cumbersome and prone to introducing contamination. Although LC-MS / MS does not require derivatization, it demands stringent mobile phase optimization; high matrix samples may inhibit ionization efficiency, requiring deuterated internal standards (such as D5-CAP) to correct errors, which is costly. Furthermore, both methods require expensive equipment and professional personnel, making them difficult to meet the needs of rapid screening at the grassroots level. Summary of the Invention

[0003] The purpose of this invention is to provide a fiber optic biosensor for chloramphenicol measurement, enabling specific detection of chloramphenicol. This invention features a compact structure, simple fabrication, high accuracy, and high sensitivity.

[0004] The technical solution adopted by this utility model to solve the technical problem is as follows:

[0005] A peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement is characterized by comprising a broadband light source SLED (1), a sensing structure (2), and an OSA spectrometer (3). The sensing structure (2) includes a single-mode fiber (201), a peanut-shaped fiber (202), a Bragg fiber grating (FBG) (203), and a surface functional modification region (204). The single-mode fiber is fused to the peanut-shaped fiber, and the other end of the peanut-shaped fiber is fused to the Bragg fiber grating (FBG). Then, a surface functional modification region is formed around the peanut-shaped fiber. The surface functional modification region (204) includes an APTES modification region (2041), a gold film (2042), and a CAP-BSA coupling region (2043). The APTES modification region, the gold film, and the CAP-BSA coupling region are formed sequentially from the inside to the outside on the peanut-shaped surface. The broadband light source SLED is connected to one end of the sensing structure (2), and the other end of the sensing structure (2) is connected to the OSA spectrometer.

[0006] The beneficial effects of this utility model are:

[0007] 1. By adopting the structure of peanut-shaped optical fiber, more light from the single-mode fiber core can be coupled into the cladding, enhancing the excitation effect of SPR effect and improving sensitivity. The wavelength shift relationship between the characteristic peak and chloramphenicol concentration can be obtained by analyzing the SPR characteristic peak drift.

[0008] 2. By using cascaded Bragg fiber gratings (FBGs), the relationship between the reflected wavelength of the FBG and temperature can be obtained by analyzing the transmission spectrum. The relationship between the SPR characteristic peak and temperature can be obtained by analyzing the SPR characteristic peak drift. This allows for the establishment of a temperature-chloramphenicol concentration sensitivity coefficient matrix, reducing the interference of temperature on chloramphenicol concentration detection, solving the cross-sensitivity problem, and improving accuracy. Attached Figure Description

[0009] Figure 1 This is a diagram of an experimental setup for a peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement, according to this invention. Figure 2 for Figure 1 A schematic diagram of the middle sensing structure (2). Figure 3 for Figure 2 A schematic diagram of the structure of the mid-surface modification functional area (204).

[0010] 1 is a broadband light source (SLED); 2 is a sensing structure; 3 is an OSA (Optical Spectrum Analyzer); 201 is a single-mode fiber; 202 is a peanut-shaped fiber; 203 is a Bragg fiber grating (FBG); 204 is a surface modification functional area; 2041 is an APTES-modified area; 2042 is a gold film; 2043 is a CAP-BSA coupling area. Detailed Implementation

[0011] The following is a detailed description of the structure and working principle of this utility model:

[0012] A peanut-shaped fiber optic biosensor for chloramphenicol measurement based on the SPR effect is characterized by including a broadband light source SLED (1), a sensing structure (2), and an OSA spectrometer (3); the sensing structure (2) includes a single-mode fiber (201), a peanut-shaped fiber (202), a Bragg fiber grating (FBG) (203), and a surface functional modification region (204); one end of the single-mode fiber (201) is fused with the peanut-shaped fiber (202) by discharge, and the other end of the peanut-shaped fiber (202) is fused with the single-mode fiber with the FBG engraved on it by discharge (203); the FBG (203) is engraved on the single-mode fiber using a femtosecond laser; the fused fiber grating is then... The sensing structure (2) was immersed in a piranha solution and oxidized at room temperature. The immersed area was rinsed with pure water and then allowed to dry naturally at room temperature. It was then immersed in an aminopropyltriethoxysilane (APTES) solution (1-5% ethanol) to introduce amino groups and form an APTES modified region (2041). A gold film was sputtered onto the surface of the APTES-treated sensing structure to form an SPR active layer and a gold film (2042). A CAP-BSA solution (0.1-1 mg / mL PBS) was coated onto the sensing structure after the gold film was coated, and the antigen was fixed by amino-glutaraldehyde crosslinking to form a CAP-BSA coupling region (2043). The broadband light source SLED (1) was connected to one end of the sensing structure (2); the other end of the sensing structure (2) was connected to the OSA spectrometer (3).

[0013] Working principle of a peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement:

[0014] A peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement Figure 1 The connections are shown. Light emitted from the broadband SLED propagates along the fiber core. When it reaches the bulge region of the peanut-shaped fiber, mode field mismatch occurs due to discontinuities in the core size, resulting in a beam splitting effect. Some core mode light is coupled into the cladding, exciting the propagation of higher-order cladding modes. At the peanut-shaped fiber bulge at the output end, the cladding mode and core mode couple again and interfere coherently. The coupled interference beam further propagates to the FBG region, where specific wavelengths are reflected while other wavelengths are transmitted. The interference spectrum is analyzed by connecting to an OSA spectrometer.

[0015] In the surface functionalized region, changes in chloramphenicol concentration lead to alterations in the local refractive index, and the gold film deposited in this region can excite the SPR effect. When the ambient refractive index changes due to variations in chloramphenicol concentration, it causes a shift in the position of the SPR characteristic peak, which is then reflected in the spectral response.

[0016] Furthermore, temperature changes also affect the biological activity of chloramphenicol. Therefore, this invention introduces a Bragg fiber grating (FBG) for temperature monitoring. Due to its high sensitivity to temperature changes, temperature-induced refractive index changes will simultaneously cause wavelength shifts in both the Bragg reflection wavelength and the SPR characteristic peak. By constructing a sensitivity coefficient matrix between temperature and chloramphenicol concentration, quantitative decoupling of the two parameters to the SPR resonance response can be achieved, effectively suppressing cross-sensitivity and improving the sensitivity and detection accuracy of the sensing system. Example

[0017] Figure 1 This is a schematic diagram of the structure of a peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement according to this utility model. In the sensing structure (2), the peanut-shaped fiber is 5cm long, the Bragg fiber grating (FBG) has a period of 500nm, a total length of 10mm, and a surface functional modification area length of 3cm; the broadband light source SLED has a spectral range of 600-1600nm, and the spectrometer used is OSA (Yokogawa AQ6370c); firstly, the single-mode fiber (201) is fused to one end of the peanut-shaped fiber (202) by discharge, and the other end of the peanut-shaped fiber (202) is fused to the single-mode fiber with the Bragg fiber grating (FBG) engraved by discharge (203). The Bragg fiber grating (FBG) (203) is engraved on the single-mode fiber using a femtosecond laser. 10 mg / mL CAP ethanol solution and 10 mg / mL BSA PBS solution were mixed at a molar ratio of 10:1, and 2% glutaraldehyde was added dropwise for 4 hours (4℃). The reaction was then terminated with 1M glycine. After dialysis purification, the mixture was lyophilized and stored. Piranha solution was prepared by mixing concentrated sulfuric acid and 30% hydrogen peroxide at a volume ratio of 3:1. The sensing structure (2) was completely immersed in the piranha solution, and the sensing area was hydroxylated for 10 minutes. After rinsing with ultrapure water, the structure was dried to better crosslink APTES. The structure was then immersed in 2% APTES ethanol solution for 30 minutes to introduce amino groups. After curing at 110℃, a 50 nm gold film was sputtered to form an SPR active layer. 0.5 mg / mL CAP-BSA PBS solution was coated on the surface of the gold film. The antigen was fixed by crosslinking with glutaraldehyde and non-specific sites were blocked with 1% BSA. The structure was rinsed with a mixture of 0.1M glycine and 10% DMF for 30 seconds to destroy the antigen-antibody binding and restore the SPR baseline.

[0018] Chloramphenicol Concentration Testing: Light emitted from a broadband SLED propagates along the fiber core. When it reaches the bulge region of the peanut-shaped fiber, mode field mismatch occurs due to discontinuities in the core size, resulting in a beam splitting effect. Some core modes are coupled into the cladding, exciting the propagation of higher-order cladding modes. In the surface functionalized region, changes in chloramphenicol concentration lead to changes in the local refractive index, and the gold film deposited in this region can excite the SPR effect. When the ambient refractive index changes due to variations in chloramphenicol concentration, it causes a shift in the position of the SPR characteristic peak. At the peanut-shaped fiber bulge at the output end, the cladding mode and the core mode couple again and interfere coherently. The coupled interference beam is further propagated to the FBG region, where specific wavelengths are reflected while other wavelengths are transmitted. The interference spectrum is analyzed by connecting to an OSA spectrometer to compare the SPR characteristic peaks with the reflected wavelengths of the FBG.

[0019] Temperature Testing: Light emitted from a broadband SLED propagates along the fiber core. When it reaches the bulge region of the peanut-shaped fiber, mode field mismatch occurs due to discontinuities in the core size, resulting in a beam splitting effect. Some core modes are coupled into the cladding, exciting the propagation of higher-order cladding modes. In the surface functionalized region, temperature changes alter the activity of chloramphenicol, leading to changes in antigen-antibody binding and resulting in different local refractive indices. The gold film deposited in this region can excite the SPR effect. When the ambient refractive index changes due to temperature, the position of the SPR characteristic peak shifts. At the peanut-shaped fiber bulge at the output end, the cladding mode and core mode couple again and interfere coherently. The coupled interference beam further propagates to the FBG region. Due to temperature changes, the grating period changes, causing a wavelength shift in specific reflected light while other wavelengths are transmitted. The interference spectrum is analyzed by connecting to an OSA spectrometer to compare the SPR characteristic peaks with the reflected wavelengths of the FBG.

[0020] The above embodiments are only one of the preferred embodiments among all the solutions of this utility model. Other simple modifications to a peanut-shaped fiber optic biosensor based on the SPR effect for chloramphenicol measurement are all within the scope of protection of this utility model.

Claims

1. A SPR based peanut type optical fiber biosensor for measurement of chloramphenicol characterized in that The system includes a broadband light source SLED (1), a sensing structure (2), and a spectrometer OSA (3). The sensing structure (2) includes a single-mode fiber (201), a peanut-shaped fiber (202), a Bragg fiber grating (FBG) (203), and a surface functional modification region (204). The single-mode fiber is fused to the peanut-shaped fiber, and the other end of the peanut-shaped fiber is fused to the Bragg fiber grating. Then, a surface functional modification region is formed around the peanut-shaped fiber. The surface functional modification region (204) includes an APTES modification region (2041), a gold film (2042), and a CAP-BSA coupling region (2043). The APTES modification region, the gold film, and the CAP-BSA coupling region are formed sequentially from the inside to the outside on the peanut-shaped surface. The broadband light source SLED is connected to one end of the sensing structure (2), and the other end of the sensing structure (2) is connected to the spectrometer OSA.

Images