Method for detecting organophosphorus pesticide by microfluidic chip based on fluorescent sensing film

Patent metadata

Field	Value
Publication number	US-12281990-B2
Application number	US-202218035938-A
Country	US
Kind code	B2
Filing date	Feb 28, 2022
Priority date	Feb 24, 2022
Publication date	Apr 22, 2025
Grant date	Apr 22, 2025

Abstract

The present invention belongs to the field of organophosphorus pesticide (OP) detection, and relates to a method for detecting an OP by a microfluidic chip based on a fluorescent sensing film. A porous fluorescent sensing film and the microfluidic chip are first constructed. The fluorescent sensing film is fabricated through layer-by-layer self-assembly of a platinum nanoparticle@oxalate-metal-organic framework (MOF) composite and a porous two-dimensional (2D) nanosheet, and has the functions of specifically detecting OPs and blocking macromolecular interferents. The microfluidic chip includes a sample channel, injection channels, reaction tanks, microfluidic channels, a detection tank, and an optical fiber channel, such that sample pretreatment and detection processes are integrated in the chip. An OP detection system is established by combining a portable constant-pressure syringe pump, a laser, a spectrometer, a signal transmitter, and a signal indicator, such that test devices are miniaturized and integrated and the OP detection is standardized.

First claim

What is claimed is:

1. A method for detecting an organophosphorus pesticide by a microfluidic chip based on a fluorescent sensing film, comprising the following steps:
step I: fabrication of a porous fluorescent sensing film:
S1: dissolving europium nitrate, pyromellitic acid, and oxalic acid in an acetonitrile-ethanol solution, stirring to obtain a mixed solution, and subjecting the mixed solution to a reaction at a specified temperature; purifying and drying to obtain a metal-organic framework powder, and redissolving the metal-organic framework powder in water to obtain a metal-organic framework solution; and
mixing an oxalate solution with the metal-organic framework solution under shaking for a specified period of time to obtain an oxalate-metal-organic framework composite solution, mixing the oxalate-metal-organic framework composite solution with a potassium chloroplatinate solution, shaking a resulting mixed solution at a specified temperature, and adding sodium borohydride to obtain a platinum nanoparticle-loaded oxalate-metal-organic framework composite solution, which is denoted as a Pt@TCPO-EuMOF solution;
S2: cleaning a quartz substrate, soaking the quartz substrate in a polydiallyldimethylammonium chloride solution, taking the quartz substrate out, soaking the quartz substrate in the Pt@TCPO-EuMOF solution obtained in S1, taking the quartz substrate out, and rinsing the quartz substrate with distilled water to obtain a Pt@TCPO-EuMOF film;
soaking the Pt@TCPO-EuMOF film successively in the polydiallyldimethylammonium chloride solution and the Pt@TCPO-EuMOF solution, taking the Pt@TCPO-EuMOF film out, and rinsing the Pt@TCPO-EuMOF film with distilled water, which is a soaking cycle; repeating the soaking cycle N times to finally form N+1 Pt@TCPO-EuMOF fluorescent sensing layers on a surface of the quartz substrate, which is denoted as a fluorescent sensing layer-modified quartz substrate, wherein N is a positive integer;
dissolving a molybdenum disulfide nanosheet, a polystyrene polymer, and polydiallyldimethylammonium chloride in ethanol according to a specified ratio to obtain a mixed solution, and soaking the fluorescent sensing layer-modified quartz substrate in the mixed solution M times to form M macromolecular barrier layers on surfaces of the fluorescent sensing layers to finally obtain an organophosphorus pesticide fluorescent sensing film comprising the fluorescent sensing layers and the macromolecular barrier layers, which is denoted as the porous fluorescent sensing film, wherein M is a positive integer;
step II: fabrication of the microfluidic chip:
wherein the microfluidic chip comprises a sample channel, reaction tanks, a detection tank, microfluidic channels, and an optical fiber channel;
a number of the reaction tanks is n, which are successively denoted as a first reaction tank, a second reaction tank, . . . a (n−1) th reaction tank, and an n th reaction tank;
a sample inlet is formed at an end of the microfluidic chip; the sample channel is formed at one end of the first reaction tank and is connected to the sample inlet, and the other end of the first reaction tank communicates with the second reaction tank, . . . the (n−1) th reaction tank, and the n th reaction tank successively through respective ones of the microfluidic channels; an end of the n th reaction tank communicates with one end of the detection tank through a corresponding one of the microfluidic channels, and the optical fiber channel is formed at the other end of the detection tank; and the detection tank does not communicate with the optical fiber channel;
n injection channels are provided at a side of the microfluidic chip, which are successively denoted as a first injection channel, a second injection channel, . . . a (n−1) th injection channel, and an n th injection channel; the first injection channel communicates with the first reaction tank, the second injection channel communicates with the second reaction tank, . . . the (n−1) th injection channel communicates with the (n−1) th reaction tank, and the n th injection channel communicates with the n th reaction tank;
a fluorescent sensing film access and visual detection port is formed above the detection tank; and the n is a positive integer;
the microfluidic chip is fabricated as follows:
using three-dimensional drawing software to design channel structures of the microfluidic chip, and with a dissolvable support material as a base material, printing a microfluidic channel model by a three-dimensional (3D) printer; fixing the microfluidic channel model in a container, pouring a mixture of polydimethylsiloxane and a curing agent thereof, and heating to a specified temperature such that the polydimethylsiloxane is hardened to obtain a microfluidic platform template; dissolving the microfluidic channel model in the microfluidic platform template with an organic solvent aqueous solution to obtain a microfluidic chip platform; pretreating an upper surface of the microfluidic chip platform such that the microfluidic channels on the upper surface communicate with an external environment;
converting a methyl group on a surface of the polydimethylsiloxane into a hydroxyl group by plasma technology, and sealing the upper surface of the microfluidic chip platform with a quartz substrate as an upper cover of the microfluidic chip platform;
forming the fluorescent sensing film access and visual detection port in a quartz substrate zone right above the detection tank for access of the fluorescent sensing film and acquisition of a fluorescence visualization signal; and processing the optical fiber channel at a side of the detection tank near an end to finally obtain a microfluidic chip for organophosphorus pesticide detection;
step III: establishment of an organophosphorus pesticide fluorescence colorimetric card and a quantitative detection model, specifically comprising the following steps:
establishing an organophosphorus pesticide microfluidic chip system, which mainly comprises a constant-pressure syringe pump, syringes, connecting tubes, a microfluidic chip, a fluorescent optical fiber, a laser, a spectrometer, a signal transmitter, and a signal indicator,
wherein the constant-pressure syringe pump is connected to the sample inlet of the microfluidic chip through a corresponding one of the connecting tubes for sample injection;
each of the syringes communicates with a respective injection channel of the injection channels through a respective one of the connecting tubes to add a reaction reagent to a respective reaction tank of the reaction tanks, wherein the reaction reagent is added to degrade acetylcholine to produce H 2 O 2 ;
one end of the fluorescent optical fiber is arranged in the optical fiber channel to acquire a fluorescence signal of the porous fluorescent sensing film in the detection tank, and the other end of the fluorescent optical fiber is connected to the laser and the spectrometer; and the spectrometer is configured to transmit an acquired porous fluorescent sensing film signal to the signal indicator through the signal transmitter;
preparing organophosphorus pesticide standards with h different concentration gradients, placing the porous fluorescent sensing film fabricated in the step I into the detection tank of the microfluidic chip, adding an organophosphorus pesticide standard of the organophosphorus pesticide standards by the constant-pressure syringe pump through the sample inlet, and adding the reaction reagent to the respective reaction tank through the respective injection channel by each of the syringes, such that the organophosphorus pesticide standard and the reaction reagent added are thoroughly mixed in the microfluidic channels to degrade the organophosphorus pesticide in the microfluidic channels into H 2 O 2 , and a reaction solution obtained after the reaction finally flows into the detection tank,

Assignees

• Univ Jiangsu

Inventors

• Hu Xuetao
• Zou Xiaobo
• Jiang Pei
• Shi Jiyong
• Zhang Xinai
• Huang Xiaowei
• Li Zhihua
• Li Yahui
• Li Wenting
• Zhang Junjun

Classifications

• G01N21/643 Primary

  non-biological material · CPC title

• C12Q1/46 Primary

  involving cholinesterase · CPC title

• C12Q1/32

  involving dehydrogenase · CPC title

• B01L2300/069

  Absorbents; Gels to retain a fluid · CPC title

• B01L2300/0654

  Lenses; Optical fibres · CPC title