CN-122016730-A - Method and device for detecting calcium ions by using optical fiber SPR-fluorescence

CN122016730ACN 122016730 ACN122016730 ACN 122016730ACN-122016730-A

Abstract

The invention belongs to the technical field of ion detection, and relates to a calcium ion detection method and device based on optical fiber SPR and fluorescence dual signals. The method comprises the steps of detecting calcium-calcein standard liquid by using an optical fiber sensing probe, establishing a dual-signal quantitative model of SPR signals and fluorescent signals, synchronously collecting dual signals of a liquid sample to be detected, and substituting signal values into the model to calculate the concentration of calcium ions. The device comprises a heterogeneous optical fiber probe module integrating an SPR and a fluorescence sensing unit, a microfluidic module for fixing a probe and transporting a sample, and a signal acquisition and processing module for synchronously exciting and acquiring double signals. According to the invention, the characteristic that the same indicator complex reaction synchronously induces the change of refractive index and fluorescence is utilized, the SPR signal and the fluorescence signal are obtained at the same time, and the two signals are verified cooperatively, so that the detection accuracy, the specificity and the anti-interference capability are obviously improved. The device integrates the microfluidic technology and has the advantages of small volume, small sample demand, quick response and simple operation.

Inventors

PENG XIAOLING
LI YANGYU
GUI XIN
Tang Hongmiao
TANG BIN
SHI SHENGHUI
LIANG YAN
DENG HAO

Assignees

重庆理工大学

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (10)

1. The method for detecting the calcium ions by using the optical fiber SPR-fluorescence is characterized by comprising the following steps of: S1, establishing a dual-signal model, namely detecting a series of calcium-calcein standard liquids with known concentrations by using an optical fiber sensing probe, synchronously acquiring Surface Plasmon Resonance (SPR) signals and fluorescent signals of the standard liquids, and establishing a dual-signal linear fitting curve model reflecting the relationship between the concentration of calcium ions and the SPR signals and the fluorescent signals; s2, synchronously collecting signals to be detected, namely synchronously collecting SPR signals and fluorescent signals in a liquid sample to be detected by using the optical fiber sensing probe; S3, calculating the concentration of calcium ions, namely substituting the SPR signal value and the fluorescent signal value acquired in the step S2 into the double-signal linear fitting curve model, and calculating to obtain the concentration of calcium ions in the liquid sample to be detected. The SPR signal is used for representing the medium refractive index change caused by the calcium-calcein complexation reaction, the fluorescent signal is used for representing the fluorescent intensity change caused by the calcium-calcein complexation reaction, and the two are used as mutually independent physical quantities to cooperatively participate in the quantitative calculation of the calcium ion concentration.
2. The method of claim 1, wherein the range of known concentrations of standard calcium-calcein solution is 200 μmol/L to 1400 μmol/L.
3. The method according to claim 1, wherein said calcein is used as a fluorescent indicator which specifically complex with calcium ions to cause a change in refractive index of a detection interface medium to excite the generation of said SPR signal, and simultaneously generates a change in fluorescence intensity under the action of excitation light to form said fluorescent signal.
4. The method for detecting calcium ions according to claim 1, further comprising the step of verifying the accuracy of the detection result by using a labeling recovery method after obtaining the detection concentration, wherein the method comprises the steps of adding a standard solution of calcium-calcein with a known concentration into the liquid sample to be detected, respectively obtaining SPR signals and fluorescence signals of the sample before and after labeling, and calculating the labeling recovery rate.
5. An apparatus for carrying out the method for detecting calcium ions according to any one of claims 1 to 4, comprising: The optical fiber sensing probe module adopts a heterogeneous optical fiber structure, and integrates an SPR sensing unit for sensing refractive index change and a fluorescence sensing unit for receiving fluorescence signals; the microfluidic module comprises a microfluidic chip (1), wherein the microfluidic chip (1) is provided with an adaptive clamping seat (A1) for fixing the optical fiber sensing probe module and a microfluidic channel for accommodating and transporting a liquid sample to be detected; the signal acquisition and processing module comprises an excitation light source (7) for exciting the fluorescent sensing unit, a broadband light source (8) for exciting the SPR sensing unit, an optical fiber coupling assembly for coupling light from the two light sources to the optical fiber sensing probe module and coupling an optical signal containing SPR and fluorescent information returned from the probe to a detection end, a spectrometer (14) for receiving the optical signal, and a data processing unit (15) for processing spectral data and calculating concentration.
6. The device of claim 5, wherein the SPR sensing unit is a gold film area positioned on the end face and the side face of the optical fiber and is responsible for sensing the refractive index change of the medium, and the fluorescent sensing unit is positioned in a solution area around the gold film and an optical fiber action area and is responsible for receiving fluorescent emission signals.
7. The device according to claim 5, characterized in that the excitation light source is a 405nm laser (7) and the broadband light source is a halogen light source (8) with an emission wavelength range covering 350-1000 nm.
8. The device according to claim 7, wherein the signal acquisition and processing module further comprises a long-wave pass filter (12) arranged in front of the optical path entrance of the spectrometer (14) for filtering the wavelength of the excitation light source (7) to pass fluorescent signals.
9. The apparatus of claim 5, wherein the heterogeneous optical fiber structure is formed by fusion-splicing a multimode optical fiber with a fine core optical fiber, and a gold film having a thickness of 40-50nm is deposited on an end region of the fine core optical fiber to constitute the SPR sensing unit.
10. The device of claim 5, wherein the microfluidic module further comprises a syringe pump, a waste reservoir, and a silica gel capillary, the silica gel capillary comprising a first capillary for connecting the syringe pump to the sample inlet of the microfluidic channel, and a second capillary for connecting the sample outlet of the microfluidic channel to the waste reservoir.

Description

Method and device for detecting calcium ions by using optical fiber SPR-fluorescence Technical Field The invention belongs to the technical field of ion detection, and relates to a method and a device for detecting calcium ions by combining optical fiber Surface Plasmon Resonance (SPR) and fluorescent dual signals. Background The concentration of calcium ions (Ca 2 +) is a key parameter for water environment monitoring, ecological research and resource utilization. The accurate, rapid and on-site detection is of great significance. At present, the detection of calcium ions mainly depends on methods such as an atomic absorption spectrometry, an inductively coupled plasma mass spectrometry, a colorimetry and the like, and the methods are accurate, but have huge equipment, complex operation and high cost, and are difficult to meet the requirements of on-site, in-situ and rapid monitoring. Therefore, the optical fiber sensing technology is introduced into the field because of the advantages of small volume, electromagnetic interference resistance, suitability for remote monitoring and the like. The existing optical fiber sensing scheme mostly adopts a single detection principle. For example, a fiber Surface Plasmon Resonance (SPR) -based sensor, such as a fiber SPR-based protein detection apparatus disclosed in chinese patent CN106526195A, has high sensitivity, but its SPR signal is susceptible to interference from temperature, salinity changes and other nonspecific adsorption in complex matrices in water, resulting in insufficient selectivity and quantitative accuracy for calcium ions. On the other hand, the optical fiber fluorescence-based sensor has strong specificity and quick response, but the fluorescence signal intensity is easily influenced by light source fluctuation, sample turbidity and scattering, and the detection stability and sensitivity face challenges, such as the optical fiber biochemical sensor disclosed in CN 113030035A. In addition, attempts have been made to fuse different principles to improve performance. A method for monitoring the concentration of calcium ions in deep tissues by utilizing the photoacoustic-fluorescence complementary principle is disclosed in CN 105548102A. However, this technology is biomedical tissue imaging, relies on photoacoustic effect and ultrasound detection, is complex in device, and is not suitable for environments requiring complex matrices and rapid detection in situ. Therefore, a technical scheme for detecting Ca2 + based on the synchronous acquisition of a spectrum signal and a fluorescence signal of an optical fiber probe under the condition of no marking and fully excavating the complementary characteristics of multi-mode information through a self-adaptive fusion mechanism is needed, so as to improve the detection sensitivity, stability and anti-interference capability. Disclosure of Invention In view of the above, the invention aims to overcome the defects that in the existing calcium ion detection technology, a large instrument is complex to operate and not portable, and an optical fiber sensor based on a single principle, such as pure SPR or pure fluorescence, has weak anti-interference capability in a complex liquid matrix, poor selectivity and insufficient detection accuracy, and is difficult to realize on-site rapid and micro detection, and provides an optical fiber SPR-fluorescence calcium ion detection method and device. The detection method comprises the following steps: S1, establishing a dual-signal model, namely detecting a series of calcium-calcein standard liquids with known concentrations by using an optical fiber sensing probe, synchronously acquiring Surface Plasmon Resonance (SPR) signals and fluorescent signals of the standard liquids, and establishing a dual-signal linear fitting curve model reflecting the relationship between the concentration of calcium ions and the SPR signals and the fluorescent signals; s2, synchronously collecting signals to be detected, namely synchronously collecting SPR signals and fluorescent signals in a liquid sample to be detected by using the optical fiber sensing probe; S3, calculating the concentration of calcium ions, namely substituting the SPR signal value and the fluorescent signal value acquired in the step S2 into the double-signal linear fitting curve model, and calculating to obtain the concentration of calcium ions in the liquid sample to be detected. The SPR signal is used for representing the medium refractive index change caused by the calcium-calcein complexation reaction, the fluorescent signal is used for representing the fluorescent intensity change caused by the calcium-calcein complexation reaction, and the two are used as mutually independent physical quantities to cooperatively participate in the quantitative calculation of the calcium ion concentration. Further, the calcein is used as a fluorescence indicator, and specifically performs complexation reaction with calcium ions to ca