CN104155280A - Self-reference quantization detection method of Raman optical fiber sensor - Google Patents

Abstract

The invention discloses a self-reference quantization detection method of a Raman optical fiber sensor, which belongs to the technical field of optical signal detection, and solves the problems of low quantization precision, high probability of environmental influences and high detection cost which are caused by the fact that an extra reference signal source needs to be set for existing trace analysis, detection and quantization of organic molecules and biological molecules, and a standard sample is likely to change. According to the quantization detection method, optical fibers for preparing the Raman optical fiber sensor are doped with semiconductor quantum dots with the Raman frequency of 100-550 cm<->, and the Raman light scattered spectrum signal intensity of the semiconductor quantum dots acts as the intensity of a standard reference signal. The method provided by the invention is high in quantization precision, is not affected by the environment, guarantees stable detection values, is free of the extra reference source of an analysis system, and is adaptive to trace detection and biomedical detection on organic molecules, biochemical bacterial warfare agents and biomolecules.

Description

Self-reference quantitative detection method of Raman optical fiber sensor

technical field

The invention belongs to the technical field of optical signal detection, and in particular relates to a self-reference quantitative detection method of a Raman optical fiber sensor.

Background technique

Raman optical fiber sensor is one of the sensing and detection methods applied to the low trace measurement of organic molecules and biomolecules in many fields. In the prior art, Raman optics including surface-enhanced Raman light scattering and Raman light scattering There have been many reports on the research of optical fiber sensors. However, the analytical detection results of most Raman optical fiber sensors are qualitative or semi-quantitative analytical detection. For the Raman optical fiber sensor for quantitative analysis and detection applications, it is necessary to use the Raman light scattering spectrum intensity of a standard sample with a known amount (or concentration) as a quantitative reference standard for analysis and detection, and quantify the signal intensity by drawing a standard curve analyze. However, the standard reference samples used for surface-enhanced Raman light scattering or Raman light scattering spectroscopy detection of various organic molecules and biomolecules are mostly organic standard samples or biological samples, and the optical properties of such samples are easily affected by time and environment And changes, thus affecting the stability, precision and accuracy of quantitative detection and inspection; In addition, for the instrument systemization of Raman optical fiber sensor, the instrument equipment needs to be equipped with standard signal reference optical path or reference source, which increases the analysis Complexity and cost of instrument design and construction.

Semiconductor quantum dots, such as CdTe, CdSe, and CdS, have low Raman light scattering frequencies. The LO phonon light scattering of CdTe is located at about 167 cm ^-1 , the LO phonon light scattering of CdSe is located at about 208 cm ^-1 and CdS The LO phonon light scattering is located at about 306 cm ^-1 . In the prior art, there are reports of doping glass with semiconductor quantum dots such as CdTe, CdSe and CdS, but these glass materials doped with semiconductor quantum dots are mainly used for the research of optical properties, and there is no relevant information about doping in optical fibers. The narrow-band low-frequency Raman light scattering signal of the medium quantum dot is used to report the reference signal intensity of the surface-enhanced Raman scattering or Raman light scattering detection of the molecule to be measured.

Contents of the invention

The purpose of the present invention is to solve the technical problems that the existing trace analysis, detection and quantification of organic molecules and biomolecules requires a separate reference signal source and the standard sample is variable, resulting in low quantification accuracy, easy to be affected by the environment, and high detection cost. A Raman optical fiber sensor self-reference quantitative detection method.

The self-reference quantitative detection method of the Raman optical fiber sensor of the present invention is to dope the semiconductor quantum dot with a Raman frequency of 100-550 ^cm in the optical fiber of the Raman optical fiber sensor, and use the Raman light of the semiconductor quantum dot The signal intensity of the scattering spectrum is used as the standard reference signal intensity of the Raman light scattering spectrum signal intensity of the analyte.

Further, it also includes taking the ratio/difference of the Raman light scattering spectrum signal intensity of the analyte and the Raman light scattering spectrum signal intensity of the semiconductor quantum dot as the quantitative analysis detection value, and then completing the analyte by drawing a standard curve. quantitative detection.

Further, the semiconductor quantum dots are CdTe, CdSe or CdS.

Further, the optical fiber is a glass optical fiber or a plastic optical fiber.

Further, the semiconductor quantum dots are doped in the fiber core or the total reflection layer of the fiber.

Further, the analytes are organic molecules, biomolecules, nanoparticles or biochemical bacterial warfare agent molecules.

Beneficial effects of the present invention:

(1) The semiconductor quantum dots CdTe, CdSe and CdS that the present invention adopts have narrow-band low-frequency Raman light scattering, and the Raman light scattering frequency of organic molecules and biomolecules is higher, generally all above 700cm ^-1 , so semiconductor Quantum dot Raman light scattering signal intensity is used as the standard reference signal intensity of the Raman light scattering signal intensity of the analyte, which does not interfere with the detection of the analyte;

(2) The self-referencing quantitative Raman optical fiber sensor of the present invention is used for instrumentation systemization, without additionally designing a standard signal reference source, which simplifies the structure of the instrument system, reduces testing costs, and improves the accuracy of the quantitative detection of the analyte Accuracy and accuracy, the detection value is stable, free from environmental interference;

(3) The doped semiconductor quantum dots of the present invention are suitable for Raman optical fiber sensors of various diameters and shapes, and are suitable for use in the entire Raman spectrum range, including surface-enhanced Raman light scattering spectroscopy detection or Raman Optical Fiber Sensors for Light Scattering Spectroscopic Detection.

Description of drawings

Fig. 1 is the Raman spectrum of 4-MBA molecule and the Raman spectrum of CdSe quantum dot in embodiment 1;

Fig. 2 is the standard curve of (I ₂₀₃ -I _analyte )/I ₂₀₃ and the concentration of analyte in embodiment 1;

Fig. 3 is the Raman spectrum of 4-MBA molecule in comparative example 1;

Fig. 4 is the standard curve in comparative example 1.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with specific embodiments, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the claims of the present invention.

The Raman optical fiber sensor self-reference quantitative detection method comprises the following steps:

(1) Doping the semiconductor quantum dots with a Raman frequency of ^100-550cm in the optical fiber for the preparation of the Raman optical fiber sensor, and then preparing the Raman optical fiber sensor, and the other components in the Raman optical fiber sensor remain unchanged, The semiconductor quantum dot is preferably CdTe, CdSe or CdS, the optical fiber can be glass optical fiber or plastic optical fiber, the doping position can be in the fiber core or the total reflection layer of the optical fiber, and the doping method is the prior art;

(2) The laser input end and the signal output end of the Raman optical fiber sensor of step (1) are coupled with the Raman spectrometer, so that the excitation light source can be coupled into the Raman optical fiber sensor, and the The Raman signal can be fed back to the analyzer for analysis;

(3) The sensing end of the Raman optical fiber sensor is inserted into the aqueous solution of the analyte or the buffer of the analyte to collect and detect the Raman signal, then the signal will be in the 100-550cm ^-1 spectral range and greater than The Raman light scattering spectrum signal intensity of the semiconductor quantum dot and the Raman light scattering spectrum signal intensity of the analyte were detected in the spectral range of 800cm ^-1 respectively, and the Raman light scattering spectrum signal intensity of the semiconductor quantum dot in the 100-550cm ^-1 spectral range The light scattering spectrum signal intensity is used as the standard reference signal intensity of the Raman light scattering spectrum signal intensity of the analyte in the spectral range greater than 800cm ^-1 ;

It is also possible to immobilize noble metal nanoparticles on the surface of the sensing end of the Raman optical fiber sensor, and combine the analyte with the noble metal nanoparticles on the surface of the optical fiber by covalent or adsorption methods for resonance surface-enhanced Raman spectroscopy analysis and detection;

(4) Analyze the relative intensity of the Raman light scattering spectrum signal of the object to be measured and the Raman light scattering spectrum signal of the semiconductor quantum dot, and then complete the detection of the object to be measured; usually the Raman light scattering spectrum signal of the object to be measured is The ratio or difference between the intensity and the Raman light scattering spectrum signal intensity of the semiconductor quantum dot is used as the quantitative Raman analysis detection value, such as the Raman light scattering spectrum of the semiconductor quantum dot Raman light scattering spectrum signal intensity I _{quantum dot} and the analyte The ratio of the difference between the signal strength I _analyte and the I _{quantum dot} , that is, (I _{quantum dot} -I _analyte )/I _{quantum dot} is the detection value of quantitative Raman analysis, and the detection value and the analyte concentration x The functional relationship draws a standard curve, and the standard curve is: (I _{quantum dot} -I _analyte )/I _{quantum dot} =a+bx, a, b are constants, and then the (I _{quantum dot} -I _analyte) obtained by detection )/I _{quantum dots} are substituted into the standard curve to obtain the analyte concentration x.

The analytes referred to in this embodiment are applicable to all substances analyzed and detected by Raman optical fiber sensors in the prior art. The common ones are organic molecules, biomolecules, nanoparticles or biochemical bacterial warfare agent molecules, and the analytes are usually used for analysis. Aqueous solution or buffer buffer; Nanoparticles (such as gold or silver nanoparticles) can be detected in any shape, such as spherical, rod, triangular and ellipsoidal.

Example 1

Embodiment 1 is illustrated in conjunction with Fig. 1 and Fig. 2

(1) Doping CdSe quantum dots in the optical fiber used by the Raman optical fiber sensor, the optical fiber is a glass optical fiber, and the doping position is in the fiber core;

(2) Coupling the laser input end and the signal output end of the Raman optical fiber sensor doped with the CdSe quantum dots in step (1) with the fluorescence analysis system;

(3) The sensing end of the Raman optical fiber sensor doped with CdSe quantum dots was directly inserted into the 4-MBA molecular solution compounded with the surface of silver nanoparticles at a concentration of 5 and 40 ng/mL respectively in a volume of 50 μL, and detected The surface-enhanced Raman spectrum of 4-MBA molecules at 1100 cm ^-1 and the Raman spectrum of CdSe quantum dots at 203 cm ^-1 , and the Raman spectrum intensity I ₂₀₃ of CdSe quantum dots at 203 cm ^-1 and 4-MBA molecules at 1100 cm ^-1 The ratio of the difference between the Raman spectrum intensity I _analyte of ¹ and I ₂₀₃ , that is (I ₂₀₃ -I _analyte )/I ₂₀₃ , and draw a standard curve as a function of this value and the concentration x of the analyte, Obtain (I ₂₀₃ -I _analyte )/I ₂₀₃ =0.2+0.41x;

(4) After the standard curve is obtained, the sensing end of the Raman optical fiber sensor in step (2) is directly inserted into 50 μL of 5, 10, 20, 30 ng/mL 4- In the MBA molecular solution, detect the surface-enhanced Raman spectrum of 4-MBA molecules at 1100cm ^-1 and the Raman spectrum of CdSe quantum dots at 203cm ^-1 , and obtain the Raman spectrum intensity I ₂₀₃ and 4 of CdSe quantum dots at 203cm ^- 1 -The ratio of the difference between the Raman spectrum intensity I of _the Raman spectrum intensity I of the MBA at 1100cm ^-1 and the I ₂₀₃ , that is, (I ₂₀₃ -I _{the analyte} )/I ₂₀₃ , which is substituted into the standard curve to obtain the concentration x of the analyte, The calculated concentration values are respectively close to 5, 10, 20, 30ng/mL, indicating that the present invention can be used for the self-reference _{quantitative detection of} Raman optical fiber sensor; The corresponding concentrations of 5, 10, 20, and 30ng/mL are the vertical and horizontal coordinates respectively, and the points determined by the horizontal and vertical coordinates are filled in the detection curve, and the obtained points are marked as a, b, c, and d in Figure 2. 2 It can be seen that the fitting value of the standard curve of Example 1 is R=0.999, indicating that the method of the present invention has higher accuracy and precision.

Fig. 1 is the surface-enhanced Raman spectrum of 4-MBA molecule and the Raman spectrum of CdSe quantum dot at 203cm ^-1 , and Fig. 2 is (I ₂₀₃ -I _analyte )/I ₂₀₃ and analyte concentration in embodiment 1 standard curve.

Comparative example 1

Illustrate Comparative Example 1 in conjunction with Fig. 3 and Fig. 4

(1) Coupling the laser input end and signal output end of the Raman optical fiber sensor without CdSe quantum dot doping with the fluorescence analysis system;

(2) Insert the Raman fiber sensor without CdSe quantum dot doping into 50 μL of the 4-MBA molecular solution compounded with the surface of silver nanoparticles at a concentration of 5 and 40 ng/mL respectively, and directly collect the 4-MBA molecule In the Raman spectrum at 1100cm ^-1 , the standard curve is drawn as a function of the Raman spectrum intensity of the 4-MBA molecules collected directly at these two concentrations at 1100cm ^-1 and the concentration of 4-MBA molecules. The standard curve is shown in Figure 4 ;

(3) Insert the Raman fiber optic sensor directly into 50 μL of the 4-MBA molecular solution compounded with the surface of silver nanoparticles with a concentration of 5, 10, 20, 30 and 40 ng/mL, respectively, and directly collect the corresponding concentration of 4-MBA Surface-enhanced Raman spectrum of molecules at 1100cm ^-1 ; the relationship between the Raman spectrum intensity of directly collected 4-MBA molecules at 1100cm ^-1 and the corresponding concentration of 4-MBA molecules is plotted on Figure 4 for its corresponding point value, are respectively a ₀ , b ₀ , c ₀ , d ₀ , e ₀ , and f ₀ , as can be seen from Figure 4, the fitting value of the standard curve and the detected value is R=0.969, indicating that the detection method of the present invention is more precise and accurate. high.

FIG. 3 is the Raman spectrum of 4-MBA molecules compounded with the surface of silver nanoparticles in Comparative Example 1; FIG. 4 is the standard curve in Comparative Example 1.

Apparently, the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those of ordinary skill in the technical field, without departing from the principle of the present invention, some improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention .

Claims (6)

1. Raman optical fiber sensor self-reference quantitative detection method, it is characterized in that, in the optical fiber of Raman optical fiber sensor, doping Raman frequency is the semiconductor quantum dot of 100-550cm ^-1 , and the Raman of semiconductor quantum dot The signal intensity of the light scattering spectrum is used as the standard reference signal intensity of the Raman light scattering spectrum signal intensity of the analyte. 2. Raman optical fiber sensor self-reference quantification detection method according to claim 1, is characterized in that, also comprises, with the Raman light scattering spectrum signal strength of analyte and the Raman light scattering spectrum signal of semiconductor quantum dot The intensity ratio/difference is used as the detection value of quantitative Raman analysis, and the quantitative detection of the analyte is completed by drawing a standard curve. 3. The Raman optical fiber sensor self-reference quantitative detection method according to claim 1 or 2, wherein the semiconductor quantum dots are CdTe, CdSe or CdS. 4. The Raman optical fiber sensor self-reference quantitative detection method according to claim 1 or 2, wherein the optical fiber is a glass optical fiber or a plastic optical fiber. 5. The Raman optical fiber sensor self-reference quantitative detection method according to claim 1 or 2, wherein the semiconductor quantum dots are doped in the fiber core or the total reflection layer of the fiber. 6. The Raman optical fiber sensor self-reference quantitative detection method according to claim 1 or 2, wherein the analyte is an organic molecule, a biomolecule, a nanoparticle or a biochemical bacterial warfare agent molecule.