Preparation, screening and application of two-dimensional red phosphorus nanosheet

Abstract

The application provides preparation, screening and application of two-dimensional red phosphorus nanosheets. The two-dimensional red phosphorus nanosheets are layered materials with a size of 600-800 nm. Blocky commercial red phosphorus is derived into two-dimensional red phosphorus nanosheets with a large surface area by simple hydrothermal treatment and ice bath ultrasonic method, the molecular adsorption capacity is improved, and the SERS signal is also improved. Then, by changing the ultrasonic time, the size of the two-dimensional red phosphorus nanosheets adjusts the visible light absorption range and the band gap, and the red phosphorus nanosheets with the strongest SERS signal are screened by Raman characterization means. The two-dimensional red phosphorus nanosheets have stable properties, low cost and application prospect in biomedicine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biological materials, and particularly relates to preparation, screening and application of two-dimensional red phosphorus nanosheets. BACKGROUND

[0002] Two-dimensional materials have rich physical properties, such as van der Waals force, which makes them have band gap-dependent layered structure. Compared with traditional semiconductor materials, emerging two-dimensional (2D) material red phosphorus (RP) has a large active area, non-toxicity, high stability, and significant electronic conductivity of layered structure. In addition, red phosphorus has a wide absorption range of visible light, and these advantages make red phosphorus have broad application prospects in the fields of photocatalysis and electrochemistry, and therefore, at present, red phosphorus materials are mostly applied in the field of photocatalysis, and it is urgent to explore in the field of tumor marker detection.

[0003] It is known that phosphorus widely exists in animal and plant tissues and participates in very important metabolic processes in life activities, and is an indispensable element of the body. Red phosphorus has good biocompatibility, and is more stable in chemical properties than white phosphorus, is more inexpensive and easy to obtain than black phosphorus, and has a wide visible light absorption range, which makes it have the potential of band gap adjustment, and is expected to achieve continuous adjustment of SERS performance, and is expected to have good application prospects in the field of biomedicine.

[0004] Moreover, with the continuous development of nanomaterial research, phosphorus-based materials are an important research field in nanoscience. Phosphorus-containing nanomaterials, especially two-dimensional materials, are prone to react with oxygen and water, and finally degrade into non-toxic phosphate and phosphonate, which are harmless to the human body and the environment. However, the complicated preparation of phosphorus-based nanomaterials greatly limits the further development of phosphorus-based nanosheets. Therefore, it is urgent to develop a simple, safe and controllable, low-cost, environmentally friendly and easy-to-prepare method for two-dimensional red phosphorus nanomaterials. SUMMARY

[0005] An advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, wherein bulk red phosphorus is converted into nanosheet-shaped red phosphorus with a large surface area by a simple and efficient method, so that the molecular adsorption capacity of red phosphorus is significantly improved.

[0006] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, wherein the change in the size of the two-dimensional red phosphorus nanosheets prepared by the present application adjusts the visible light absorption range and the band gap thereof, and the two-dimensional red phosphorus nanosheets with the optimal SERS performance are obtained through characterization and screening.

[0007] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, wherein the two-dimensional red phosphorus nanosheets with the strongest Raman signal are screened by using a Raman laser, and the most optimal substrate is used to facilitate the application in the detection of SERS tumor markers.

[0008] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, wherein the red phosphorus has good biocompatibility and is harmless to the human body and the environment, which is conducive to environmental protection.

[0009] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, which is suitable for application in the detection of tumor markers, and the two-dimensional red phosphorus nanosheets are used as an immune substrate to construct a sandwich structure, and then combined with a 3D immune probe, which can significantly improve the sensitivity of SERS detection.

[0010] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, which has a simple preparation method, low cost and wide application range.

[0011] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, which has a simple preparation method, low cost and wide application range.

[0012] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, which has a simple preparation method, low cost and wide application range.

[0013] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, which has a simple preparation method, low cost and wide application range.

[0014] Another advantage of the present application is to provide a preparation, screening and application of two-dimensional red phosphorus nanosheets, which has a simple preparation method, low cost and wide application range.

[0015] According to an aspect of the present application, a preparation method of two-dimensional red phosphorus nanosheets is provided, comprising the following steps:

[0016] (1) grinding the bulk red phosphorus, and sieving with a screen;

[0017] (2) preparing a red phosphorus solution from the red phosphorus, and ultrasonicating;

[0018] (3) transferring the sample into an autoclave, and treating in a water bath;

[0019] (4) centrifuging and dispersing, washing, and taking the lower precipitate;

[0020] (5) ultrasonicating; and

[0021] (6) centrifuging.

[0022] In the step (1), the red phosphorus is ground with a mortar and sieved with a 300-mesh screen.

[0023] In the step (2), 1 g of red phosphorus is added into 60 ml of deionized water to prepare a red phosphorus solution with a concentration of 1 / 60 g / mL, and ultrasonicated for 30 min.

[0024] In the step (3), the sample is transferred into a 100-ml stainless steel autoclave with a polytetrafluoroethylene liner, and treated in a water bath at 200°C for 12 h.

[0025] In the step (4), the red phosphorus after the water bath treatment is centrifuged and dispersed, and then washed with anhydrous ethanol and deionized water for three times, respectively, and the lower precipitate is taken.

[0026] In the step (5), the red phosphorus obtained in the step (4) is dissolved in deionized water, and then transferred into an ultrasonic instrument, wherein the ultrasonic instrument is a probe-type ultrasonic instrument, and the ultrasonic power is 100 W.

[0027] In the step (5), the working time of the probe-type ultrasonic instrument is 5 s, and the intermittent time is 3 s, and the working time and the intermittent time are mutually spaced, and there are 99 times as a working cycle, and according to different working cycles, the following red phosphorus samples are obtained in turn: RP-0 without ultrasonicating, RP-2 taken out every two working cycles, RP-4 ultrasonicated for 4 working cycles, RP-8 ultrasonicated for 8 working cycles, RP-12 ultrasonicated for 12 working cycles, and RP-16 ultrasonicated for 16 working cycles.

[0028] In the step (6), the suspensions of the above RP-0, RP-4, RP-8, RP-12 and RP-16 are centrifuged at 4000 r / min for 10 min, and the supernatant is taken out, and two-dimensional red phosphorus nanosheets are obtained, wherein the size of the two-dimensional red phosphorus nanosheets gradually decreases with the increase of the ultrasonic cycle.

[0029] RP-0 has a size of 1-3 μm, RP-2 has a size of 400-450 nm, RP-4 has a size of 350-400 nm, RP-8 has a size of 300-3500 nm, RP-12 has a size of 200-300 nm, and RP-16 has a size of 100-200 nm.

[0030] According to another aspect of the present application, the present application further provides a screening method of two-dimensional red phosphorus nanosheets, comprising the following steps:

[0031] (A) dropping the prepared supernatant of two-dimensional red phosphorus nanosheets onto a 0.5*0.5 silicon wafer;

[0032] (B) drying at 60°C;

[0033] (C) dropping crystal violet molecules and drying again;

[0034] (D) testing the red phosphorus sample by using a Raman laser;

[0035] (E) drawing a Raman spectrum and selecting a substrate with the strongest Raman signal.

[0036] In the step (A), the supernatant of red phosphorus is RP-0, RP-2, RP-4, RP-8, RP-12 and RP-16, wherein the solution of each red phosphorus sample is 1 mg / mL, and the concentration of crystal violet in the step (C) is 1*10 -2 mg / mL.

[0037] In the above steps, a 532 nm Raman laser is used as an excitation source, the laser spot diameter is 12.5 mm, the laser power is 1 mw, and the integration time is 10 s.

[0038] According to another aspect of the present application, the present application further provides a two-dimensional red phosphorus nanosheet, which is a layered material and has a size of 600-800 nm.

[0039] According to another aspect of the present application, the present application further provides an application of two-dimensional red phosphorus nanosheets, wherein the layered two-dimensional red phosphorus nanosheets with a size of 600-800 nm are used as an immune substrate to construct a sandwich structure for the detection of SERS tumor markers. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a scanning electron microscope photo of RP-0 prepared according to a first preferred embodiment of the present application.

[0041] Figure 2 is a scanning electron microscope photo of RP-2 prepared according to the above first preferred embodiment of the present application.

[0042] Figure 3 is a scanning electron microscope image of RP-4 prepared according to the above first preferred embodiment of the present application.

[0043] Figure 4 is a scanning electron microscope image of RP-8 prepared according to the above first preferred embodiment of the present application.

[0044] Figure 5 is a scanning electron microscope image of RP-12 prepared according to the above first preferred embodiment of the present application.

[0045] Figure 6 is a scanning electron microscope image of RP-16 prepared according to the above first preferred embodiment of the present application.

[0046] Figure 7 is a Raman spectrum plotted from the Raman detection results of RP-0, RP-4, RP-8, RP-12, RP-16 against crystal violet prepared according to the above first preferred embodiment of the present application.

[0047] Figure 8 is a comparison result of Raman spectrum plotted from the Raman detection results of RP-2, RP-4, RP-8, RP-12 against crystal violet prepared according to the above preferred embodiment of the present application.

[0048] Figure 9 is a scanning electron microscope image of two-dimensional black phosphorus nanosheets (BP NSs) prepared according to the above preferred embodiment of the present application.

[0049] Figure 10 is a Raman spectrum plotted from the Raman detection results of RP-0, BP and RP-16 against crystal violet prepared according to the above preferred embodiment of the present application. DETAILED DESCRIPTION

[0050] The following description is presented to enable any person skilled in the art to practice the present application as claimed. The preferred embodiments disclosed herein are only examples of the present application and alternative embodiments will be apparent to those skilled in the art. The patentable scope of the present application is defined by the appended claims and can include other embodiments that offer optional preferred alternatives.

[0051] In the application, two-dimensional red phosphorus nanosheets are efficiently prepared by a hydrothermal method and an ice bath ultrasonic method, and a 532 nm Raman laser is used as a laser source to test each two-dimensional red phosphorus nanosheet sample prepared, so as to screen out two-dimensional red phosphorus with the strongest Raman signal as the optimal substrate, so as to construct a sandwich structure by taking two-dimensional red phosphorus as an immune substrate, and combine with an immune probe with a 3D structure, so as to be used for SERS tumor marker detection. The aggregation of molecules on the two-dimensional layered material is avoided, the sensitivity of SERS detection is improved, a non-noble metal substrate is used, and various defects existing in the traditional noble metal substrate are overcome, and the accuracy and convenience of detection are improved.

[0052] The application provides a preparation method of two-dimensional red phosphorus nanosheets.

[0053] (1) Grinding bulk red phosphorus and sieving to obtain a ground red phosphorus sample;

[0054] (2) Preparing a red phosphorus solution from the red phosphorus sample and ultrasonically treating the solution;

[0055] (3) Transferring the sample solution into a high-pressure kettle and treating with a water bath;

[0056] (4) Centrifuging and dispersing, washing, and taking the lower precipitate;

[0057] (5) Ultrasonically treating and taking a sample; and

[0058] (6) Centrifuging. Example 1

[0059] In the step (1), a small amount of bulk red phosphorus (RP) is ground in a mortar, and then a 300-mesh sieve is used to sieve and obtain a ground red phosphorus sample;

[0060] In the step (2), 1 g of the red phosphorus sample is added into 60 ml of deionized water to prepare a red phosphorus solution with a concentration of 1 / 60 g / ml, and the solution is ultrasonically treated for 30 min;

[0061] In the step (3), the sample in the step (2) is transferred into a 100-ml polytetrafluoroethylene-lined stainless steel high-pressure kettle, and is subjected to hydrothermal treatment at 200 DEG C, and the water bath treatment time is 12 h;

[0062] In the step (4), after the water bath treatment is completed, the obtained sample is centrifuged and dispersed, and then is washed with anhydrous ethanol and deionized water for three times respectively, and the lower precipitate is taken;

[0063] The step (5) comprises the following two steps:

[0064] Step (501): The red phosphorus obtained in the above step (4) is dissolved in deionized water again, and is transferred to an ultrasonic instrument, which is preferably a probe-type ultrasonic instrument.

[0065] The ultrasonic power of the probe-type ultrasonic instrument is 100 W, the working time is 5 seconds, the intermittent time is 3 seconds, the working time and the intermittent time are alternated, and there are 99 times in total, which is called one working cycle.

[0066] Step (502): First, a part of the non-ultrasonic red phosphorus sample is taken as RP-0, and then the red phosphorus sample after ultrasonic treatment for 2 working cycles is taken as RP-2.

[0067] In the step (6), the above RP-2 suspension is centrifuged at 4000 rpm for 10 min to remove the non-ultrasonic blocky red phosphorus, the supernatant is taken out, and two-dimensional red phosphorus nanosheets (RP-2) are obtained, which are placed in a refrigerator and packaged for storage.

[0068] Figure 1 The scanning electron microscope photo of RP-0 prepared in the first embodiment of the present disclosure is shown; from Figure 1 It can be seen that RP-0 is a non-ultrasonic red phosphorus sample, and the wrinkles on the side indicate that the blocky red phosphorus is composed of multiple layers of closely packed sheets, with a size of about 1 micrometer to 3 micrometers.

[0069] Figure 2 The scanning electron microscope photo of RP-2 prepared in the first embodiment of the present disclosure is shown; from Figure 2 It can be seen that the red phosphorus sample is not a blocky material before ultrasonic treatment, and gradually changes to a layered material after two cycles of ultrasonic treatment, and the size gradually decreases, wherein the size of RP-2 is about 400 nanometers to 450 nanometers. Embodiment Two

[0070] In the step (1), a small amount of blocky red phosphorus (RP) is ground in a mortar, and then a 300-mesh sieve is used to obtain a ground red phosphorus sample;

[0071] In the step (2), 1 g of the above red phosphorus sample is added to 60 ml of deionized water to prepare a red phosphorus solution with a concentration of 1 / 60 g / ml, and is ultrasonically treated for 30 min;

[0072] In the step (3), the sample in the step (2) is transferred to a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and is hydrothermally treated at 200°C, with a water bath treatment time of 12 h;

[0073] In the step (4), after the water bath treatment is completed, the obtained sample is centrifugally dispersed, and then the lower precipitate is taken after being washed with anhydrous ethanol and deionized water for 3 times respectively;

[0074] The step (5) comprises the following two steps:

[0075] Step (501): The red phosphorus obtained in the above step (4) is dissolved in deionized water again, and is transferred into an ultrasonic instrument, which is preferably a probe type ultrasonic instrument.

[0076] The ultrasonic power of the probe type ultrasonic instrument is 100 W, the working time is 5 seconds, the intermittent time is 3 seconds, the working time and the intermittent time are alternated, and there are 99 times in total, which is called one working cycle.

[0077] Step (502): The red phosphorus sample after 4 working cycles of ultrasonic treatment is taken as RP-4.

[0078] In the step (6), the above RP-4 suspension is centrifuged at 4000 rpm for 10 min to remove the non-ultrasonic blocky red phosphorus, and the supernatant is taken out to obtain two-dimensional red phosphorus nanosheets (RP-4), which is placed in a refrigerator and packaged for storage.

[0079] Figure 3 The scanning electron microscope photo of the RP-4 prepared in the embodiment one of the present disclosure; from Figure 3 It can be seen that the PR-4 obtained after four treatment cycles is a layered material, that is, the non-ultrasonic RP-0 is converted into a layered material after four working cycles of ultrasonic treatment, and the size is smaller, wherein the size of the RP-4 is about 350 nanometers to 400 nanometers. Embodiment three

[0080] In the step (1), a small amount of blocky red phosphorus (RP) is ground in a mortar, and then a 300 mesh screen is used to take out the ground red phosphorus sample;

[0081] In the step (2), 1 g of the above red phosphorus sample is added into 60 ml of deionized water to prepare a red phosphorus solution with a concentration of 1 / 60 g / ml, and is ultrasonically treated for 30 min;

[0082] In the step (3), the sample in the step (2) is transferred into a 100 ml polytetrafluoroethylene lined stainless steel autoclave, and is hydrothermally treated at 200℃, and the water bath treatment time is 12 h;

[0083] In the step (4), after the water bath treatment is completed, the obtained sample is centrifugally dispersed, and then the lower precipitate is taken after being washed with anhydrous ethanol and deionized water for 3 times respectively;

[0084] The step (5) comprises the following two steps:

[0085] Step (501): The red phosphorus obtained in the above step (4) is dissolved in deionized water again, and is transferred to an ultrasonic instrument, which is preferably a probe-type ultrasonic instrument.

[0086] The ultrasonic power of the probe-type ultrasonic instrument is 100 W, the working time is 5 seconds, the intermittent time is 3 seconds, the working time and the intermittent time are alternated, and there are 99 times in total, which is called one working cycle.

[0087] Step (502): The red phosphorus sample after 8 working cycles of ultrasonic treatment is taken as RP-8.

[0088] In the step (6), the above RP-8 suspension is centrifuged at 4000 rpm for 10 min to remove the non-ultrasonic blocky red phosphorus, and the supernatant is taken out to obtain two-dimensional red phosphorus nanosheets (RP-8), which is placed in a refrigerator and packaged for storage.

[0089] Figure 4 The scanning electron microscope photo of the RP-8 prepared in Example Three of the present disclosure; from As can be seen from Figure 4 , after ultrasonic treatment, the red phosphorus sample is converted from blocky material to layered material, and the size of the RP-8 obtained after 8 treatment cycles is about 300 nanometers to 350 nanometers. Example Four

[0090] In the step (1), a small amount of blocky red phosphorus (RP) is ground in a mortar, and then a 300-mesh sieve is used to screen to obtain a ground red phosphorus sample;

[0091] In the step (2), 1 g of the above red phosphorus sample is added to 60 ml of deionized water to prepare a red phosphorus solution with a concentration of 1 / 60 g / ml, and is ultrasonically treated for 30 min;

[0092] In the step (3), the sample in the step (2) is transferred to a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and is hydrothermally treated at 200°C, with a water bath treatment time of 12 h;

[0093] In the step (4), after the water bath treatment is completed, the obtained sample is centrifuged and dispersed, and then the lower precipitate is taken after being washed with anhydrous ethanol and deionized water for 3 times respectively;

[0094] The step (5) comprises the following two steps:

[0095] Step (501): The red phosphorus obtained in the above step (4) is dissolved in deionized water again, and is transferred to an ultrasonic instrument, which is preferably a probe-type ultrasonic instrument.

[0096] The ultrasonic power of the probe-type ultrasonic instrument is 100 W, the working time is 5 seconds, the intermittent time is 3 seconds, the working time and the intermittent time are alternated, and there are 99 times in total, which is called one working cycle.

[0097] Step (502): The red phosphorus sample after 12 working cycles of ultrasonic treatment is taken as RP-12.

[0098] In the step (6), the above RP-12 suspension is centrifuged at 4000 rpm for 10 min to remove the non-ultrasonic blocky red phosphorus, the supernatant is taken out, and two-dimensional red phosphorus nanosheets (RP-12) are obtained, which are placed in a refrigerator and packaged for storage.

[0099] Figure 5 The scanning electron microscope photo of the RP-12 prepared in Example Four of the present disclosure; from Figure 5 It can be seen that after ultrasonic treatment, the red phosphorus sample is transformed from blocky to layered, and the size of RP-12 after 12 cycles of ultrasonic treatment is about 200 nm to 300 nm on average. Example Five

[0100] In the step (1), a small amount of blocky red phosphorus (RP) is ground in a mortar, and then a 300-mesh sieve is used to take out the ground red phosphorus sample;

[0101] In the step (2), 1 g of the above red phosphorus sample is added to 60 ml of deionized water to prepare a red phosphorus solution with a concentration of 1 / 60 g / ml, and is ultrasonically treated for 30 min;

[0102] In the step (3), the sample in the step (2) is transferred to a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and is hydrothermally treated at 200°C, with a water bath treatment time of 12 h;

[0103] In the step (4), after the water bath treatment is completed, the obtained sample is centrifugally dispersed, and then the lower precipitate is taken out after being washed with anhydrous ethanol and deionized water for 3 times respectively;

[0104] The step (5) includes the following two steps:

[0105] Step (501): The red phosphorus obtained in the above step (4) is dissolved in deionized water again, and is transferred to an ultrasonic instrument, which is preferably a probe-type ultrasonic instrument.

[0106] The ultrasonic power of the probe ultrasonic instrument is 100 W, the working time is 5 seconds, the interval time is 3 seconds, the working time and the interval time are alternated, and there are 99 times in total, which is referred to as one working cycle.

[0107] Step (502): Take the red phosphorus sample after 16 working cycles of ultrasonic as RP-16.

[0108] In the step (6), the above RP-16 suspension is centrifuged at 4000 rpm for 10 min to remove the non-ultrasonic blocky red phosphorus, the supernatant is taken out, and two-dimensional red phosphorus nanosheets (RP-16) are obtained and placed in a refrigerator for packaging and storage.

[0109] Figure 6 The scanning electron microscope photo of the RP-16 prepared in the fifth embodiment of the present disclosure; from Figure 6 It can be seen that after ultrasonic treatment, the red phosphorus sample is converted from a blocky material to a layered material, and the size of the RP-16 is about 100-200 nanometers on average. Embodiment six

[0110] In order to compare with red phosphorus, a black phosphorus sample is prepared by the same method as that for preparing the red phosphorus sample, so as to compare the structural changes of red phosphorus and black phosphorus after the same conditions. The specific preparation method of the black phosphorus sample (BPNSs) is as follows.

[0111] In the step (1), a small amount of blocky red black phosphorus (BP) is ground into black phosphorus powder in a mortar, and then a 300-mesh sieve is used to obtain the ground black phosphorus sample;

[0112] In the step (2), 1 g of the above black phosphorus sample is added into 60 ml of deionized water to prepare a black phosphorus solution with a concentration of 1 / 60 g / ml, and ultrasonic treatment is performed for 30 min;

[0113] In the step (3), the black phosphorus sample solution in the step (2) is transferred into a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and hydrothermal treatment is performed at 200°C, and the water bath treatment time is 12 h;

[0114] In the step (4), after the water bath treatment is completed, the obtained sample is centrifuged and dispersed, and then the lower precipitate is taken out after being washed with anhydrous ethanol and deionized water for 3 times respectively;

[0115] The step (5) includes the following two steps:

[0116] Step (501): The black phosphorus obtained in the step (4) is dissolved in deionized water again, and is transferred into an ultrasonic instrument, which is preferably a probe ultrasonic instrument.

[0117] The probe ultrasonic instrument has an ultrasonic power of 100 W, a working time of 5 seconds, and an intermittent time of 3 seconds, and the working time and the intermittent time are alternately arranged, and the peeling is performed for 4 hours.

[0118] Step (502): taking the black phosphorus sample after peeling for 4 hours as the BPNSs.

[0119] In the step (6), the above BPNSs suspension is centrifuged at 2000 pm for 10 min to remove the non-ultrasonic bulk black phosphorus, the upper dispersion liquid is centrifuged at 10000 pm for 10 min, the supernatant is taken out, the black phosphorus nanosheet (BPNSs) is obtained, and the black phosphorus nanosheet is placed in a refrigerator and packaged for storage.

[0120] Figure 9 The scanning electron microscope photos of the BPNSs prepared in the fifth embodiment of the present disclosure are shown; from Figure 9 It can be seen that after ultrasonic treatment, the size of the ultrasonic black phosphorus nanosheet is about 1500 nm to 2000 nm on average.

[0121] The present application also provides a screening method of two-dimensional red phosphorus nanosheet, wherein the screening method comprises the following steps:

[0122] (A) taking the supernatant of the prepared two-dimensional red phosphorus nanosheet and dropping it on a 0.5*0.5 silicon wafer;

[0123] (B) drying at 60°C;

[0124] (C) dropping the crystal violet molecule and drying again;

[0125] (D) testing the red phosphorus sample by using a Raman laser;

[0126] (E) drawing a Raman spectrum and selecting the substrate with the strongest Raman signal.

[0127] In the step (A), 20 microliters of the supernatant of the two-dimensional red phosphorus nanosheet (RP-0, RP-2, RP-4, RP-8, RP-12, RP-16 and BPNSs) prepared in the embodiments one, two, three, four, five and six is taken and dropped on a 0.5*0.5 silicon wafer.

[0128] In the steps (B) and (C), drying is performed at a temperature of 60°C, then 20 microliters of crystal violet (Crystal Violet, CV) is dropped, and drying is performed again.

[0129] In the step (D), a Raman laser with a laser wavelength of 532 nm is used as an excitation source, the laser spot diameter is 12.5 microns, the numerical aperture is 0.55, the laser power is set to 1 mw, and the integration time is 10 s. Five samples are tested respectively, and the Raman spectrum is drawn, and the strongest Raman signal base is selected

[0130] Figure 7 The SERS spectrum of RP-0, RP-4, RP-8, RP-12, RP-16 on crystal violet is shown, and the Raman signal at 1616 cm -1 -1, 7010, 5423, 4652, 3488, respectively, wherein the SERS enhancement effect of RP-4 is the best.

[0131] Figure 8 The SERS spectrum of RP-2, RP-4, RP-8, RP-12 on crystal violet is shown, and the Raman signal at 1616 cm -1 -1, 7010, 5423, 4652, respectively, wherein the SERS enhancement effect of RP-4 is the best, and the enhancement factor reaches 10 5 .

[0132] Figure 10 The SERS spectrum of RP-0, RP-16 and BPNSs on crystal violet (CV) is shown, and the Raman signal at 1616 cm -1 -1, 3488, 2744, respectively, from Figure 10 It can be seen that the SERS performance of black phosphorus nanosheet is obviously weaker than that of RP, and from the above experimental process, it can be seen that the ultrasonic time required for peeling the BP nanosheet is longer. Although the SERS performance of RP from bulk to layered material is improved, the enhancement factor is only 10 4 .

[0133] Through the above comparison, we can find that in the present application, bulk black phosphorus and bulk red phosphorus can be converted to layered materials after ultrasonic treatment, but through experiments, it is found that compared with red phosphorus, black phosphorus takes longer time to peel off, and after peeling off, the SERS performance of black phosphorus nanosheet is not as good as that of red phosphorus nanosheet, therefore, red phosphorus nanosheet is more suitable as a substrate.

[0134] Moreover, through the comparison of red phosphorus nanosheets with different ultrasonic cycles, it is found that the SERS signal enhancement of red phosphorus nanosheet (RP-4) after four ultrasonic cycles is the best, and it is more suitable as a substrate.

[0135] In the present application, first, by adopting a simple hydrothermal treatment and ice bath ultrasonic method, the bulk red phosphorus is derived into two-dimensional red phosphorus nanosheets with large surface area, the molecular adsorption capacity is improved, and the SERS signal is also improved; second, by changing the ultrasonic time, the size of the two-dimensional red phosphorus nanosheets adjusts the visible light absorption range and the band gap, and the red phosphorus nanosheets with the strongest SERS signal are screened out through Raman characterization means. Third, red phosphorus can be degraded into non-toxic phosphate, has biocompatibility, and has stable properties, low cost, and application prospect in biomedicine.

[0136] In order to improve the sensitivity of SERS detection of tumor markers, a sandwich structure is constructed based on the optimal red phosphorus nanosheet substrate, and the introduction of 3D MoS2 NFs as an immune probe avoids the aggregation of molecules on the two-dimensional layered material, and also effectively reduces the interference of the fluorescence background.

[0137] That is, through the above experiments and test results, it can be known that through the preparation method of the two-dimensional red phosphorus nanosheet provided by the present application, two-dimensional red phosphorus nanosheets can indeed be obtained, and the Raman signal enhancement factor of the two-dimensional red phosphorus nanosheet is higher than that of black phosphorus nanosheet. Moreover, through the comparison of the Raman signal spectrum between the two-dimensional red phosphorus nanosheets with different ultrasonic cycles, it can be found that the two-dimensional red phosphorus nanosheet with four ultrasonic cycles is a layered material, and the Raman signal enhancement effect is the best, and it is most suitable as a substrate and most suitable for application in the detection of tumor markers.

[0138] Therefore, the two-dimensional red phosphorus nanosheet (RP-4) with the best performance can be used as an immune substrate to construct a sandwich structure, and then combined with a 3D immune probe, the sensitivity of SERS detection can be significantly improved.

[0139] The preparation method of the two-dimensional red phosphorus nanosheet provided by the present application is simple, the two-dimensional red phosphorus nanosheet prepared has good performance and strong Raman signal, which opens up a new research direction for the application of phosphorus-based nanomaterials in the field of tumor detection, and this is helpful for the expansion and application of phosphorus-based nanomaterials in the field of tumor marker detection.

[0140] Those skilled in the art will understand that the embodiments of the present application shown in the above description and the accompanying drawings are only examples and do not limit the present application. The purpose of the present application has been completely and effectively achieved. The function and structural principle of the present application has been shown and explained in the embodiments, and the embodiments of the present application can have any modification or modification without departing from the principle.

Claims

1. A method for preparing two-dimensional red phosphorus nanosheets, characterized by, The method comprises the following steps: (1) grinding bulk red phosphorus and sieving with a screen; (2) preparing a red phosphorus solution from the red phosphorus and ultrasonating; (3) transferring the red phosphorus solution to an autoclave and treating in a water bath; (4) centrifugally dispersing, washing and taking the lower precipitate; (5) ultrasonating using a probe-type ultrasonic instrument, taking samples, wherein the working time of the probe-type ultrasonic instrument is 5 s, the intermittent time is 3 s, the working time and the intermittent time are mutually spaced, and a working cycle comprises 99 times, and according to different working cycles, the following red phosphorus samples are obtained in turn: RP-0 is not ultrasonated, RP-2 is taken out every two working cycles, and RP-4, RP-8, RP-12 and RP-16 are taken out every four working cycles in turn; (6) centrifuging to obtain supernatant of two-dimensional red phosphorus nanosheets, and dropping the supernatant of the two-dimensional red phosphorus nanosheets onto a silicon wafer and drying; (7) dropping crystal violet molecules and drying again to obtain two-dimensional red phosphorus nanosheets; and (8) testing the two-dimensional red phosphorus nanosheets using a Raman laser, drawing a Raman spectrum and selecting a substrate with the strongest Raman signal.

2. The method for preparing two-dimensional red phosphorus nanosheets according to claim 1, wherein in the step (1), the red phosphorus is ground with a mortar and sieved through a 300-mesh screen.

3. The method for preparing two-dimensional red phosphorus nanosheets according to claim 2, wherein in the step (2), 1 g of red phosphorus is added to 60 ml of deionized water to prepare a red phosphorus solution with a concentration of (1 / 60) g / mL, and ultrasonated for 30 min.

4. The method for preparing two-dimensional red phosphorus nanosheets according to claim 3, wherein in the step (3), the red phosphorus solution is transferred to a 100-ml stainless steel autoclave with a polytetrafluoroethylene liner, and treated in a water bath at 200 ℃ for 12 h.

5. The method for preparing two-dimensional red phosphorus nanosheets according to claim 4, wherein in the step (4), the red phosphorus after water bath treatment is centrifugally dispersed, then washed with anhydrous ethanol and deionized water for three times respectively, and the lower precipitate is taken.

6. The method for preparing two-dimensional red phosphorus nanosheets according to claim 5, wherein in the step (5), the red phosphorus obtained in the step (4) is dissolved in deionized water and then transferred to an ultrasonic instrument, wherein the ultrasonic instrument is a probe-type ultrasonic instrument, and the ultrasonic power is 100 W.

7. The method for preparing two-dimensional red phosphorus nanosheets according to claim 6, wherein in the step (6), the suspensions of RP-0, RP-2, RP-4, RP-8, RP-12 and RP-16 are centrifuged at 4000 r / min for 10 min, and the supernatant is taken to obtain two-dimensional red phosphorus nanosheets, wherein the size of the two-dimensional red phosphorus nanosheets gradually decreases with the increase of the ultrasonic cycle.

8. The method of claim 7, wherein the size of RP-0 is 1-3 μm, the size of RP-2 is 400-450 nm, the size of RP-4 is 350-400 nm, the size of RP-8 is 300-3500 nm, the size of RP-12 is 200-300 nm, and the size of RP-16 is 100-200 nm.

9. The method of claim 1, wherein a 532 nm Raman laser is used as an excitation source, the laser spot diameter is 12.5 mm, the laser power is 1 mw, and the integration time is 10 s.

10. The two-dimensional red phosphorus nanosheets prepared according to the preparation method of any one of claims 1 to 8, characterized in that, The two-dimensional red phosphorus nanosheet is a layered material with a size of 300-400 nm.

11. Use of two-dimensional red phosphorus nanosheets prepared according to the production method of any one of claims 1 to 8, characterized in that, The layered two-dimensional red phosphorus nanosheet with a size of 300-400 nm is used as an immune substrate to construct a sandwich structure for SERS tumor marker detection.

Images