A gas-sensitive optical sensor array, its fabrication method and application

Abstract

This invention discloses a gas-sensitive optical sensor array, its fabrication method, and its application. The gas-sensitive optical sensor array includes at least one of photoelectric sensing materials, wherein the photoelectric sensing material is Au nanoparticles, Au-S-(CH2)6CH3, Au-S-(CH2)9CH3, Au-S-PEG300-OH, Au-S-PEG400-OCH3, Au-S-PEG600-(CH2)2-COOH, or Au-S-PEG6. The invention develops a class of gold nanomaterials with superior photoelectric properties. Based on colorimetric methods, it further enhances the detection performance of array sensors with gas-solid interface interactions, improving the sensitivity of the sensor array to photochemical pollutants to the parts-per-billion (ppt) concentration level. Furthermore, it can characteristically distinguish different types of photochemical gases and their mixtures, thereby upgrading this technology into an ultrasensitive, visual optical sensor.

Description

Technical Field

[0001] This invention relates to the field of portable ultrasensitive detection technology for photochemical pollutants in the atmospheric environment, specifically to a gas-sensitive optical sensor array, its preparation method, and its application. Background Technology

[0002] The World Health Organization (WHO) classifies volatile organic compounds (VOCs) and industrial inorganic pollutants as a significant category of substances that can cause air and water pollution. Various organic and inorganic pollutants are ubiquitous in industrial production and daily life, and among them, photochemical pollutants are a significant category that not only causes chronic harm to the human body but can also, in severe cases, lead to carcinogenic, teratogenic, and mutagenic effects. For example, when the concentration of nitrogen dioxide in the air of a work area exceeds 20 mg / m³... 3 Or the nitrogen dioxide concentration in the indoor air exceeds 0.05 mg / m³ per hour. 3 When these conditions occur, the likelihood of photochemical pollutants causing disease in humans increases significantly. Therefore, detecting ultra-low concentrations of photochemical pollutants in indoor and outdoor environments is of great importance for environmental monitoring and disease prevention.

[0003] Currently, the mainstream technologies for detecting photochemical pollutants are based on high-precision standard gas chromatography, mass spectrometry, ion mobility spectrometry, spectroscopy, and "electronic nose" methods based on semiconductor heterojunctions or conductive polymers. However, the practical application of large instruments such as gas chromatographs or mass spectrometers is greatly limited because they are expensive, complex to operate, and not portable, making real-time gas monitoring in complex testing environments impossible. Traditional spectroscopic methods (such as infrared, ultraviolet, Raman, and photoionization methods) can generally only determine a few types of organic molecules containing specific functional groups, failing to achieve the separation, qualitative and quantitative analysis of multi-component gas mixtures in complex environments. The traditional electronic nose method, proposed in the 1980s, generally uses metal oxides (SnO2, ZnO, NiO, etc.) or conductive polymers as sensing elements, utilizing surface adsorption or the electrical signal generated by a single redox reaction (the reaction of the analyte with oxygen in the air) to identify simple VOC molecules. This method has limitations such as high operating temperature (generally >120℃), low detection limit, poor selectivity, complex detection equipment, and susceptibility to environmental interference (such as temperature and humidity changes).

[0004] Because most photochemical pollutants are small molecules with relatively simple chemical structures, they are prone to escape and difficult to capture and concentrate. As a result, there have been few inventions and reports of highly efficient and accurate in-situ detection technologies in recent years. Furthermore, high-precision standard gas chromatography, mass spectrometry, ion mobility spectrometry, and spectroscopy relying on large laboratory instruments, as well as "electronic nose" methods based on semiconductor heterojunctions or conductive polymers, cannot efficiently and quickly solve this problem in the fields of analytical chemistry and environmental monitoring. Summary of the Invention

[0005] In order to solve the problems raised in the above background art, the object of the present invention is to provide a gas-sensitive optical sensor array, a preparation method thereof, and an application thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a sensing material with optoelectronic properties, and the sensing material with optoelectronic properties is a gold nanomaterial, a ligand-functionalized gold nanomaterial;

[0007] The ligand is selected from one of HS-(CH2)6CH3, HS-(CH2)9CH3, HS-PEG300-OH, HS-PEG400-OCH3, HS-PEG600-(CH2)2-COOH, HS-PEG600-(CH2)2-COO-t-Bu, HS-PEG600-(CH2)2-OCH3, HS-PEG600-(CH2)2-NH2, HS-PEG600-(CH2)2-CONHPh, HS-PEG600-(CH2)2-CONH(CF2)8CH2CH3, HS-PEG600-(CH2)2-CONH(CH2)8CH=CH(CH2)7CH3 (PEG + number represents a polyethylene glycol chain with a corresponding molecular weight).

[0008] Further, the sensing material with optoelectronic properties is Au nanoparticles, Au-S-(CH2)6CH3, Au-S-(CH2)9CH3, Au-S-PEG300-OH, Au-S-PEG400-OCH3, Au-S-PEG600-(CH2)2-COOH, Au-S-PEG600-(CH2)2-COO-t-Bu, Au-S-PEG600-(CH2)2-OCH3, Au-S-PEG600-(CH2)2-NH2, Au-S-PEG600-(CH2)2-CONHPh, Au-S-PEG600-(CH2)2-CONH(CF2)8CH2CH3, Au-S-PEG600-(CH2)2-CONH(CH2)8CH=CH(CH2)7CH3.

[0009] On the other hand, the present invention provides a preparation method for any one of the above-mentioned sensing materials with optoelectronic properties. When the sensing material with optoelectronic properties is a gold nanomaterial, the method includes the following steps:

[0010] (1) Dissolve ascorbic acid in an organic solvent (such as dichloromethane) to obtain an ascorbic acid solution;

[0011] (2) Mix the chloroauric acid solution with the ascorbic acid solution described in step (1), then add the sodium borohydride solution dropwise while stirring continuously until the solution color gradually darkens to golden yellow; evaporate the organic solvent from the obtained product to obtain a brown solid, and after washing with organic solvent and water twice and drying, obtain gold nanomaterials.

[0012] Preferably, the concentration of the ascorbic acid solution is 0.05-0.2 mM;

[0013] Preferably, the concentration of the chloroauric acid solution is 20-25 mM;

[0014] Preferably, the concentration of the sodium borohydride solution is 0.05-0.2M;

[0015] Preferably, the volume ratio of the chloroauric acid solution, ascorbic acid solution, and sodium borohydride solution is 10:5:1;

[0016] When the photoelectric sensing material is a ligand-functionalized gold nanomaterial, the following steps are included:

[0017] (1) Dissolve the thiol ligand in an organic solvent (such as dichloromethane) to obtain a ligand solution;

[0018] (2) Mix the chloroauric acid solution with the ligand solution described in step (1), then add the sodium borohydride solution dropwise while stirring continuously until the solution color gradually darkens to golden yellow; evaporate the organic solvent from the obtained product to obtain a brown solid, and after washing with organic solvent and water twice and drying, obtain ligand-functionalized gold nanomaterials.

[0019] Preferably, the concentration of the ligand solution is 0.05-0.2 mM;

[0020] Preferably, the concentration of the chloroauric acid solution is 20-25 mM;

[0021] Preferably, the concentration of the sodium borohydride solution is 0.05-0.15M;

[0022] Preferably, the volume ratio of the chloroauric acid solution, the ligand solution, and the sodium borohydride solution is 10:5:1.

[0023] On the other hand, the present invention provides a gas-sensitive optical sensor array comprising at least one of the photoelectric sensing materials described above.

[0024] Furthermore, it also includes a carrier on which the photoelectric sensing material described above is printed.

[0025] Furthermore, the carrier includes paper chips, glass slides, and flexible polymer substrates (such as polymethyl methacrylate (PMMA) and polydimethylsiloxane (PDMS)).

[0026] Furthermore, it also includes O-rings and polycarbonate card slots.

[0027] In another aspect, the present invention provides a method for fabricating any of the above-described gas-sensitive optical sensor arrays, comprising the following steps:

[0028] (1) The carrier is hydrophobically treated;

[0029] (2) Dissolve gold nanomaterials or ligand-functionalized gold nanomaterials in water to obtain gold nano inks with a concentration greater than 20 mM (a more obvious visual signal can be detected when the gold nano products are concentrated to a concentration greater than 20 mM).

[0030] (3) Gold nano-ink is printed onto a hydrophobically treated carrier using a microarray chip spotter with a spotting needle;

[0031] Preferably, the water contact angle of the hydrophobicated carrier surface is 110-120°;

[0032] Preferably, the concentration of the gold nano-ink is 50 mM.

[0033] In another aspect, the present invention provides an application of any of the above-described gas-sensitive optical sensor arrays in detecting photochemical pollutants in the atmosphere.

[0034] The beneficial effects of this invention are as follows: This invention develops a class of gold nanomaterials with superior photoelectric properties, further improving the detection performance of this type of gas-solid interface array sensor based on colorimetry. The sensitivity of the sensor array to photochemical pollutants is increased to the part-in-a-billion (ppt) concentration level, and it can characteristically distinguish different types of photochemical gases and their mixtures, thus upgrading the technology to an ultrasensitive, visual optical sensor. Subsequently, a simple optical signal acquisition device based on portable micro-devices is built to conveniently and quickly scan, analyze, and build a database of the red, green, and blue optical signals before and after the array sensor reaction. Ultimately, real-time, convenient, ultrasensitive, and wide-range visual detection of the target gas is achieved, providing a theoretical basis and practical evidence for the practical application and commercialization of this technology in the detection of photochemical polluting gases. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the gas-sensitive optical sensor array structure in Embodiment 2 of the present invention;

[0036] Figure 2To investigate the gas reaction mechanism using ozone (O3) as an example;

[0037] Figure 3 The diffuse reflectance spectrum of sensor material No. 8 after reacting with different photochemical pollutants (1 ppm concentration) for 5 minutes;

[0038] Figure 4 This is a transmission electron microscope (TEM) image of the sensing material at point number 8 after it reacts with air or NO2.

[0039] Figure 5 The qualitative response pattern of the gas-sensitive optical sensor array prepared in Example 2 to 15 photochemical gases at a concentration level of 500 ppb for 5 minutes is shown.

[0040] Figure 6 The results show the quantitative analysis of four typical photochemical pollutants (NO2, O3, SO2, CH3COONO3) by the gas-sensitive optical sensor array prepared in Example 2. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and specific examples. The following embodiments or drawings are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0042] This invention utilizes a wet synthesis process to create a series of ligand-functionalized gold nanomaterials as a type of gas-sensitive optical sensor. By leveraging the superior local surface plasmon resonance properties of gold nanoparticles during gas-solid surface reactions, ultrasensitive detection and resolution of most photochemical pollutants are achieved. Gold nanomaterials are stable in air, resistant to oxidation, and possess high hydrophobicity, effectively preventing interference from external water vapor on the resistivity response during sensor operation. Furthermore, a variety of gold nanoparticle probes can be selected, including different morphologies, sizes, and ligand functionalizations, resulting in products with varying optical response sensitivities. This method yields a series of sensing materials with different photoelectric properties. Array sensors are fabricated on disposable carriers such as paper chips or glass slides using a needle-printing method, constructing appropriately sized laboratory-on-a-chip devices suitable for gas phase detection. This enables precise detection of various photochemical pollutants (single components and mixtures) at concentration levels of one part per billion (ppt).

[0043] Example 1: Preparation of 12 photoelectric sensing materials

[0044] Point number 1: Au-S-(CH2)6CH3

[0045] Point number 2: Au-S-(CH2)9CH3

[0046] Point number 3: Au-S-PEG300-OH

[0047] Point number 4: Au-S-PEG400-OCH3

[0048] Point number 5: Au-S-PEG600-(CH2)2-COOH

[0049] Point number 6: Au-S-PEG600-(CH2)2-COO-t-Bu

[0050] Point number 7: Au-S-PEG600-(CH2)2-OCH3

[0051] Point number 8: Au-S-PEG600-(CH2)2-NH2

[0052] Point number 9: Au-S-PEG600-(CH2)2-CONHPh

[0053] Point number 10: Au-S-PEG600-(CH2)2-CONH(CF2)8CH2CH3

[0054] Point number 11: Au-S-PEG600-(CH2)2-CONH(CH2)8CH=CH(CH2)7CH3

[0055] Point number 12: Au nanoparticles

[0056] Eleven thiol ligands or ascorbic acid were dissolved in 5 mL of dichloromethane to obtain 0.1 mM solutions of each ligand or ascorbic acid. A chloroauric acid mother liquor (0.5 mL, 25 mM) was mixed with the above ligand solutions. Sodium borohydride (0.5 mL, 0.1 M) was then added dropwise to the mixture while stirring continuously, and the solution color was observed to gradually deepen to a golden yellow. The product was subjected to rotary evaporation to remove the dichloromethane. The resulting brown solid was washed twice with organic solvent and water, dried, and then redissolved in 0.2 mL of water to obtain a 50 mM gold nano-ink. All 12 developed gold nano-inks exhibited good chemical stability; no significant aggregation or fading was observed within six months of preparation.

[0057] Example 2: Fabrication of a gas-sensitive optical sensor array

[0058] Using a glass slide as a carrier, and taking the 12 photoelectric sensing materials prepared in Example 1 as an example: A 75×25mm glass slide was sequentially treated with piranha solution and n-octyltriethoxysiloxane solution to hydrophobize the surface, resulting in a water contact angle of 115° on the hydrophobized slide surface. The 12 gold nano-inks synthesized in Example 1 (with diverse surface ligands that can form various sensors with different chemical properties, enhancing detection discrimination) were printed onto the surface-treated glass slide using a microarray chip spotting instrument (manufacturer: Beijing Biochip) with a spotting needle (divided into two rows, each row with 12 element dots, the second row repeating the first row). The photoelectric sensing materials were deposited on the non-permeable glass slide, forming circular sensor element dots. Each dot used approximately 30 nL of solvent and had a diameter of 0.4 mm. After solvent evaporation, it exhibited a characteristic brown color.

[0059] The printed glass slides were then assembled with O-rings and polycarbonate slots to form a detection microdevice, which was applied to the detection of photochemical pollutants. The detection microdevice measures 78 mm in length, 27 mm in width, and 9 mm in height. Its structural schematic diagram is shown below. Figure 1 As shown (the O-ring is embedded in a grooved polycarbonate slot and protrudes approximately 1 mm above the center plane of the slot. The front of the printed glass slide is pressed tightly against the O-ring and held in place by 12 protruding parts, thus forming a narrow, sealed airflow channel similar to an athletic track inside for gas detection. Both the inlet and outlet ports are located on the polycarbonate slot, on the left and right sides respectively.)

[0060] Subsequently, a simple optical signal acquisition device based on portable micro-devices was built to conveniently and quickly scan, analyze, and build a database of red, green, and blue optical signals before and after the sensor array reaction, ultimately achieving real-time, convenient, ultra-sensitive, and wide-range visual detection of the target gas.

[0061] Taking ozone (O3) as an example, the gas reaction mechanism is as follows: ozone, as a strong oxidant, induces ligands to peel off from the surface of gold nanoparticles, thereby causing the aggregation of gold nanoparticles. Taking ozone (O3) and element number 8 as an example, as... Figure 2 As shown, the reaction of element 8 with the photochemical gas ozone (O3) mainly depends on the conversion of amino groups to nitro groups and the formation of disulfide bonds between thiol groups, thereby causing the aggregation of gold nanoparticles and resulting in a visible signal. A small amount of the sensing material at point 8 prepared in Example 1 was reacted with different photochemical pollutants (1 ppm concentration) for 5 minutes, and its diffuse reflectance spectrum was measured as follows. Figure 3 As shown, the transmission electron microscope (TEM) image of point number 8 after the sensor material reacts with air or NO2 is as follows. Figure 4 As shown, the scale bar of the TEM image is 10 nm. From Figure 3 and Figure 4 The sensor material observed at point number 8 showed a strong response to a photochemical gas with strong oxidizing properties.

[0062] Example 3: Qualitative detection of 15 photochemical gases at a concentration level of 500 ppb using the gas-sensitive optical sensor array prepared in Example 2 over a 5-minute period.

[0063] The gas-sensitive optical sensor array prepared in Example 2 was used to perform qualitative detection of 15 photochemical gases at a concentration level of 500 ppb for 5 minutes. The test was conducted at 50% relative humidity, and was performed 5 times. The average value of the 5 parallel tests was taken. The qualitative response pattern is shown below. Figure 5 As shown, the pattern displays the red-green-blue (ΔRGB) signal response value of each gold nanoparticle in the array to each pollutant gas. The figure shows that the different responses of different element points to the same detected gas result in different response patterns, which can be used as a qualitative and quantitative basis for different photochemical pollutants. The response intensity mainly depends on the oxidizing power of the detected gas; the stronger the oxidizing power of the pollutant, the higher the average response intensity. For weakly oxidizing or reducing gases (such as ethylene and isoprene), the response pattern is weak and almost negligible. In summary, the sensor responses to 15 photochemical pollutants revealed that, based on the oxidizing properties of these gaseous compounds, they exhibit differentiated response patterns. This allows for the establishment of a molecular fingerprint-like material analysis mechanism for the identification and classification of different types of photochemical gases.

[0064] Example 4: Quantitative detection of four typical photochemical pollutants using the gas-sensitive optical sensor array prepared in Example 2.

[0065] The gas-sensitive optical sensor array prepared in Example 2 was used to quantitatively detect four typical photochemical pollutants (NO2, O3, SO2, CH3COONO3), and the results are as follows: Figure 6 As shown, a represents nitrogen dioxide (NO2), b represents ozone (O3), c represents sulfur dioxide (SO2), and d represents acetyl peroxynitrate (CH3COONO3). In each graph, the horizontal axis represents the concentration of the detected gas, and the vertical axis represents the rate of change of the response intensity over time (in minutes). The curves showing the rate of change of response intensity with concentration exhibit a clear linear relationship (R² calculated using the least squares method). 2 =0.997), and based on the approximately linear response intensity with concentration, accurate quantitative results (i.e., the slope of each curve) can be obtained. The slopes of the linear function curves are calculated as follows: nitrogen dioxide, 1.09; ozone, 0.89; sulfur dioxide, 0.82; acetyl peroxynitrate, 0.72.

[0066] In summary, the qualitative and quantitative results of the gas-sensitive optical sensor array in this application can be used in field atmospheric environmental monitoring to determine the types and contents of unknown photochemical pollutants.

[0067] The above description is only a specific embodiment of the present invention and not all embodiments. Any equivalent modifications made by those skilled in the art to the technical solutions of the present invention by reading the present invention specification shall be covered by the claims of the present invention.

Claims

1. A gas-sensitive optical sensor array for detecting photochemical pollutants in the atmosphere, characterized in that, It includes a carrier and multiple sensing units printed on the carrier, wherein the sensing units include photoelectric sensing materials. The photoelectric sensing materials are gold nanomaterials and ligand-functionalized gold nanomaterials. The photoelectric sensing materials are Au nanoparticles, Au-S-(CH2)6CH3, Au-S-(CH2)9CH3, Au-S-PEG300-OH, Au-S-PEG400-OCH3, Au-S-PEG600-(CH2)2-COOH, and Au-S-PEG600-(CH2)2-COO-. t -Bu, Au-S-PEG600-(CH2)2-OCH3, Au-S-PEG600-(CH2)2-NH2, Au-S-PEG600-(CH2)2-CONHPh, A u-S-PEG600-(CH2)2-CONH(CF2)8CH2CH3, Au-S-PEG600-(CH2)2-CONH(CH2)8CH=CH(CH2)7CH3.

2. The gas-sensitive optical sensor array according to claim 1, characterized in that, The carrier is hydrophobically treated, and its surface water contact angle is 110-120°.

3. The gas-sensitive optical sensor array according to claim 1, characterized in that, The carrier includes one of paper chips, glass slides, and flexible polymer substrates.

4. The gas-sensitive optical sensor array according to claim 1, characterized in that, It also includes O-rings and polycarbonate card slots.

5. The gas-sensitive optical sensor array according to claim 1, characterized in that, The preparation method of gold nanomaterials includes the following steps: (1) Dissolve ascorbic acid in an organic solvent to obtain an ascorbic acid solution; (2) Mix the chloroauric acid solution with the ascorbic acid solution described in step (1), then add the sodium borohydride solution dropwise while stirring continuously until the solution color gradually darkens to golden yellow; evaporate the organic solvent from the obtained product to obtain a brown solid, and after washing with organic solvent and water twice and drying, obtain gold nanomaterials. The concentration of the ascorbic acid solution is 0.05-0.2 mM; The concentration of the chloroauric acid solution is 20-25 mM; The concentration of the sodium borohydride solution is 0.05-0.2 M; The volume ratio of the chloroauric acid solution, ascorbic acid solution, and sodium borohydride solution is 10:5:1; The preparation method of ligand-functionalized gold nanomaterials includes the following steps: (1) Dissolve the thiol ligand in an organic solvent to obtain a ligand solution; (2) Mix the chloroauric acid solution with the ligand solution described in step (1), then add the sodium borohydride solution dropwise while stirring continuously until the solution color gradually darkens to golden yellow; evaporate the organic solvent from the obtained product to obtain a brown solid, and after washing with organic solvent and water twice and drying, obtain ligand-functionalized gold nanomaterials. The concentration of the ligand solution is 0.05-0.2 mM; The concentration of the chloroauric acid solution is 20-25 mM; The concentration of the sodium borohydride solution is 0.05-0.2 M; The volume ratio of the chloroauric acid solution, ligand solution, and sodium borohydride solution is 10:5:

1.

6. A method for fabricating a gas-sensitive optical sensor array, the method being used to fabricate a gas-sensitive optical sensor array as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) The carrier is hydrophobically treated; (2) Dissolve gold nanomaterials and ligand-functionalized gold nanomaterials in water to obtain gold nano-inks with a concentration greater than 20 mM. (3) Gold nano-ink is printed onto a hydrophobically treated carrier using a microarray chip spotting instrument and a spotting needle.

7. The preparation method according to claim 6, characterized in that, The concentration of the gold nano-ink is 50 mM.

8. The application of a gas-sensitive optical sensor array as described in any one of claims 1 to 5 in detecting photochemical pollutants in the atmosphere.

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