An ultrahydrophobic microneedle patch integrating micro-invasive blood sampling and SERS blood detection functions, and a preparation method and application thereof

Abstract

The application discloses an integrated minimally invasive blood sampling and SERS blood detection function super-hydrophobic microneedle patch and a preparation method and application thereof, and belongs to the field of clinical laboratory medicine and biosensing technology. The microneedle sampling layer containing arrayed conical protrusions is prepared by mold casting-vacuum forming, the microneedle sampling layer is sequentially modified with a polydopamine coating, a silver nanoparticle array layer and a hydrophobic protective layer, and a super-hydrophobic microneedle patch integrating sampling-enhancement-detection is constructed. The super-hydrophobic microneedle patch can realize minimally invasive and painless blood sampling, can highly sensitively detect hemoglobin and glucose and other substances in blood based on the surface-enhanced Raman spectroscopy effect, the detection time is less than 1 min, the anti-biological interference capability is strong, large equipment is not needed, and the super-hydrophobic microneedle patch can be directly deployed in a street blood donation scene, significantly improves blood donation screening efficiency and safety, and can solve the problems that the existing blood donation screening technology relies on large equipment, the sampling invasiveness is strong, and the detection efficiency is low.

Description

Technical Field

[0001] This invention belongs to the field of clinical laboratory medicine and biosensor technology, specifically relating to a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions, its preparation method, and its application. Background Technology

[0002] In clinical diagnosis and daily health management, the accuracy and convenience of detecting biomarkers such as hemoglobin, blood glucose, and tyrosine directly determine the scientific validity and timeliness of assessments of human health status, playing an irreplaceable role in the diagnosis, monitoring, and prognosis of various diseases. Changes in hemoglobin levels and structural abnormalities are crucial references for doctors in diagnosing diseases such as sickle cell anemia and acute myocardial injury; dynamic and precise control of blood glucose levels is a core requirement for the management of diabetic patients; and tyrosine metabolism disorders are closely related to the development and progression of malignant diseases such as Parkinson's disease and tumors. Therefore, developing a technology that can rapidly, minimally invasively, and with high sensitivity simultaneously detect multiple biomarkers has always been a critical issue that urgently needs to be addressed in clinical practice and health management.

[0003] Currently, commonly used biomarker detection methods in clinical and routine applications generally suffer from numerous unavoidable shortcomings, affecting not only detection efficiency and accuracy but also significantly limiting their applicability and scope of application. Regarding adaptability to different testing scenarios, traditional methods heavily rely on large-scale biochemical analyzers and ELISA readers. These devices are bulky, complex to operate, and can only function in fixed laboratory environments, making them unsuitable for outdoor scenarios such as mobile street screenings. Furthermore, sample transport typically takes over 30 minutes, resulting in low detection efficiency and failing to meet the practical needs of immediate testing. In terms of sampling experience and compliance, traditional testing often employs venipuncture, a method that carries significant pain and infection risks. Statistics show that approximately 15%–20% of potential blood donors and those undergoing health screenings forgo testing or blood donation due to concerns about puncture-related risks, significantly reducing screening and recruitment efficiency and imposing a substantial physiological and psychological burden on patients requiring long-term monitoring. In terms of detection accuracy and anti-interference ability, the biological matrix such as proteins and lipids contained in blood samples are prone to non-specific adsorption during the detection process, resulting in high background noise and poor signal stability. Among these issues, the false positive rate is high, which seriously affects the reliability of the test results. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions, as well as its preparation method and application, to solve the technical problems of existing blood donation screening technology that rely on large equipment, have strong sampling invasiveness, low detection accuracy and low efficiency.

[0005] To achieve the above objectives, the present invention employs the following technical solution: The first aspect of the present invention discloses a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions, comprising a microneedle sampling layer, wherein a polydopamine coating, a silver nanoparticle array layer and a hydrophobic protective layer are sequentially laminated on the surface of the microneedle sampling layer. The microneedle sampling layer is composed of a thermoplastic polyurethane integrally molded substrate and an array of conical protrusions grown on the substrate.

[0006] Preferably, the hydrophobic protective layer is a superhydrophobic coating formed by modification with 1H,1H,2H,2H-perfluorodecyl mercaptan.

[0007] In a second aspect, this invention discloses a method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions. The method involves injecting a thermoplastic polyurethane solution into a microneedle mold to obtain a microneedle sampling layer; forming a polydopamine coating on the surface of the microneedle sampling layer through dopamine self-polymerization; depositing silver nanoparticles on the surface of the polydopamine coating to form a silver nanoparticle array layer; and preparing a hydrophobic protective layer on the surface of the silver nanoparticle array layer to obtain the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions.

[0008] Preferably, the thermoplastic polyurethane solution is formed by mixing thermoplastic polyurethane with N,N-dimethylformamide.

[0009] Preferably, silver nanoparticles are deposited on the surface of the polydopamine coating by chemical reduction to form a silver nanoparticle array layer.

[0010] More preferably, dilute ammonia is added dropwise to silver nitrate solution to obtain silver ammonia solution; the microneedle sampling layer modified with polydopamine coating is immersed in silver ammonia solution to achieve the deposition of silver nanoparticles.

[0011] Preferably, a hydrophobic protective layer is prepared on the surface of the silver nanoparticle array layer by vapor treatment with 1H,1H,2H,2H-perfluorodecylthiol to obtain a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions.

[0012] A third aspect of the present invention discloses the application of a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions in blood testing.

[0013] The fourth aspect of the present invention discloses a method for detecting blood substances using a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions. Capillary whole blood is collected through an array of conical protrusions on the superhydrophobic microneedle patch, and then Raman spectroscopy is used to detect the collected capillary whole blood. Qualitative analysis is achieved through characteristic peak comparison to obtain the detection results of the substances to be tested in the blood.

[0014] Preferably, the detection is performed under the condition of an excitation wavelength of 532 nm.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood testing functions. 1) The microneedle sampling layer contains an array of conical protrusions, enabling minimally invasive and painless blood collection. The entire microneedle sampling layer is made of flexible, highly elastic, and biocompatible thermoplastic polyurethane, which avoids skin inflammation and allergic reactions during blood collection and does not contaminate the blood sample, ensuring the accuracy of subsequent SERS test results. 2) In the polydopamine coating, dopamine, rich in catechol structures, can be oxidized and self-polymerized under alkaline conditions to form polydopamine (PDA). This not only has excellent adhesion properties, firmly binding inorganic and organic material surfaces, but also the abundant catechol groups on the surface can reduce silver ions in situ, providing a reliable interface basis for subsequent nano-metal loading. 3) The silver nanoparticle array layer can construct a continuous and dense conductive network on the microneedle surface, giving the material stable and excellent conductivity. At the same time, this array has a large specific surface area and uniform distribution characteristics, which can exert a good broad-spectrum antibacterial effect and reduce the risk of infection from transdermal use. Furthermore, silver nanoparticle arrays can construct micro-nano rough morphologies, achieve efficient hydrophobic modification in conjunction with low surface energy reagents, and firmly adhere to the substrate surface through in-situ growth of polydopamine, with strong interlayer bonding, stable overall structure, and good biocompatibility; 4) The design of the hydrophobic protective layer can repel hydrophilic interfering substances (such as proteins, lipids, salt ions, etc.) in blood samples through hydrophobic interactions, reduce non-specific adsorption to lower background noise, avoid signal crosstalk during multi-marker detection, and protect the internal nano-metal layer from oxidation and corrosion, maintain SERS signal stability and detection repeatability, and further synergistically enrich hydrophobic target molecules, improving the molecular enrichment efficiency and detection sensitivity of microneedles; 5) By hydrophobically modifying the silver-based surface-enhanced Raman spectroscopy (SERS) active substrate, hydrophobic interfaces can effectively repel hydrophilic interfering substances such as proteins and salt ions, reducing non-specific adsorption; at the same time, target molecules can be selectively enriched and concentrated to the plasma hot spot region, improving signal intensity and stability while reducing background noise, thereby reducing false positive rate and significantly improving the accuracy and reliability of detection results. The fabricated superhydrophobic microneedle patch integrates "sampling-enhancement-detection" and possesses excellent superhydrophobicity. Even after treatment under harsh conditions such as extreme temperature and UV aging, its superhydrophobic properties remain, demonstrating excellent environmental stability. Based on the SERS effect, it can highly sensitively detect substances such as hemoglobin and glucose in blood with a detection time of <1 min. It has strong resistance to biological interference, requires no large equipment, and can be directly deployed in street blood donation scenarios, significantly improving the efficiency and safety of blood donation screening. It can solve the pain points of existing blood donation screening technologies, such as reliance on large equipment, highly invasive sampling, and low detection efficiency, and has important clinical application value and industrialization prospects.

[0016] This invention provides a method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood testing functions. The method employs an ordered modification sequence: polydopamine coating → nano-metal functional layer → hydrophobic protective layer. 1) Using flexible, highly elastic, and biocompatible thermoplastic polyurethane as the substrate material, an ordered array of microneedles is prepared using a template replication method to form a microneedle sampling layer. 2) Utilizing the self-polymerization properties of dopamine in a weakly alkaline environment, a polydopamine coating is applied to the surface of the microneedle sampling layer. Its strong adhesion ensures a stable bond between the functional layers and the microneedle sampling layer. Simultaneously, the catechol groups of polydopamine are used to in-situ reduce silver nanoparticles, uniformly loading silver nanoparticles to construct a silver nanoparticle array layer, effectively improving the uniformity of the SERS substrate and preserving the protective layer. 3) A silver-based conductive layer is deposited on the microneedle sampling layer modified with polydopamine coating to construct a silver nanoparticle array layer. The high sensitivity enhancement of SERS is achieved by relying on the local surface plasmon resonance effect. Combined with the local enrichment effect of microneedles, the enrichment efficiency of target molecules is improved and the detection limit is reduced to meet the needs of early clinical disease screening. 4) Low surface energy hydrophobic modification is carried out using 1H,1H,2H,2H-perfluorodecylthiol to modify the hydrophobic protective layer. The hydrophobic interface repels biological matrices such as proteins and lipids in the blood, reduces non-specific adsorption and signal interference, and achieves signal fidelity for simultaneous detection of multiple biomarkers. At the same time, the good combination of polydopamine and microneedle matrix further optimizes the biocompatibility of the material.

[0017] This invention provides a method for detecting blood substances using a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions. After collecting the blood sample using the superhydrophobic microneedle patch, irradiation with 532 nm excitation light will produce multiple characteristic peaks in the Raman spectrum, among which 676 cm⁻¹ is the most prominent. -1 The peak originates from the pyrrole breathing vibration of the heme group in hemoglobin, 758 cm⁻¹ -1 The peak originates from the deformation vibration of heme pyrrole, 1132 cm⁻¹ -1 The peak is related to the CO stretching vibration of glucose, at 1173 cm⁻¹. -1 The peak corresponds to the vibrational mode of tyrosine, indicating that this method can simultaneously detect multiple biomarkers in blood samples. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the fabrication process of the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions of the present invention. Figure 2 This is a schematic diagram illustrating the blood testing using the superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood testing functions according to the present invention. Figure 3The images show scanning electron microscope (SEM) images of the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions at different preparation stages of the present invention; where (a) TPU; (b) PT; (c) APT; (d) FAPT; scale bar: 200 μm; Figure 4 The following are material element analysis diagrams of the coatings at different preparation stages of the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions of the present invention; wherein, (a) XPS full spectrum of TPU, PT, APT, and FAPT; (b) C 1s XPS spectrum of TPU and PT; (c) O 1s XPS spectrum of TPU and PT; (d) Ag 3d XPS spectrum of APT; (e) F 1s XPS spectrum of FAPT; Figure 5 The figures show the hydrophobicity test results of the coating surface of the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions at different preparation stages of the present invention; where (a) is the contact angle of TPU, PT, APT, and FAPT; (b) is the water contact angle of FAPT after being placed at different temperatures for 24 hours; (c) is the water contact angle during the UV lamp irradiation process; and (d) is the contact angle at different tilt angles. Figure 6 This is a diagram showing the optical morphological evolution of blood concentrated on the surface of a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions according to the present invention. Figure 7 This invention utilizes a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions to detect Raman spectra of donor blood samples; where the horizontal axis represents the Raman shift (cm). -1 ); ordinate: Raman intensity (au); excitation wavelength: 532 nm; integration time: 10 s; Figure 8 shows the stability repeatability verification results of the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions of the present invention; where (a) is a single SERS spectrum of different blood samples on the surface of the superhydrophobic microneedle patch, and SERS spectra of different blood samples measured at 20 points on the surface of the superhydrophobic microneedle patch; (b) Sample 1; (c) Sample 2; (d) Sample 3. Detailed Implementation

[0019] To enable those skilled in the art to understand the features and effects of the present invention, the following description and definitions are only general descriptions of the terms and expressions mentioned in the specification. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0024] In this article, "room temperature" refers to a temperature of approximately 20°C to 35°C, or approximately 23°C to 28°C, or approximately 25°C. It can be 20°C, 25°C, 30°C, or 33°C.

[0025] This invention provides a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood testing functions, including a microneedle sampling layer, wherein the surface of the microneedle sampling layer is sequentially coated with a polydopamine (PDA) coating, a silver nanoparticle (AgNPs) array layer and a hydrophobic protective layer. The microneedle sampling layer is composed of an integrally molded thermoplastic polyurethane (TPU) substrate and an array of conical protrusions grown on the substrate. The hydrophobic protective layer is a superhydrophobic coating modified with 1H,1H,2H,2H-perfluorodecyl mercaptan (PFDT).

[0026] This invention also provides a method for preparing the aforementioned superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions, such as... Figure 1As shown, firstly, a thermoplastic polyurethane solution is injected into a microneedle mold to obtain a microneedle sampling layer; secondly, a polydopamine coating is formed on the surface of the microneedle sampling layer by dopamine self-polymerization; then, silver nanoparticles are deposited on the surface of the polydopamine coating by chemical reduction to form a silver nanoparticle array layer; finally, a hydrophobic protective layer is prepared on the surface of the silver nanoparticle array layer by PFDT vapor treatment to obtain a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions.

[0027] This invention also provides a method for blood testing using a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions, such as... Figure 2 As shown, capillary whole blood was collected through an array of conical protrusions on the surface of a superhydrophobic microneedle patch. Then, the collected capillary whole blood was detected by a Raman spectrometer with an excitation wavelength of 532 nm. Qualitative analysis was achieved by comparing characteristic peaks to obtain the blood test results.

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading this description, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0029] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0030] I. Preparation of a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood testing functions 1. Preparation of TPU casting solution: Thermoplastic polyurethane (TPU) particles were added to N,N-dimethylformamide (DMF) and mixed. The mixture was then magnetically stirred at 70°C for 4 h until the TPU particles were completely dissolved, thus obtaining a 10 wt% uniform TPU casting solution, which provides a stable precursor for microneedle molding. 2. Preparation of the microneedle sampling layer: After the TPU casting solution obtained in step 1 has cooled to room temperature, it is injected into a polydimethylsiloxane (PDMS) microneedle molding mold (20). In the 50 array, air bubbles in the mold are removed by vacuum degassing process, and TPU casting liquid is added to ensure the integrity of the patch structure; then it is naturally dried and cured at room temperature, demolded, and the microneedle sampling layer (TPU) is obtained. 3. Modification of polydopamine (PDA) coating: Weigh 0.2 g of dopamine hydrochloride (DA) powder and dissolve it in 100 mL of 10 mM Tris-HCl buffer solution with a pH of 8.5 to prepare a dopamine oxidative polymerization reaction solution; Immerse the microneedle sampling layer obtained in step 2 into the dopamine oxidative polymerization reaction solution and stir magnetically at room temperature for 24 h to allow dopamine hydrochloride to oxidize and polymerize on the surface of the microneedle sampling layer to form a polydopamine coating; After the reaction is completed, wash the sample three times each with ethanol and ultrapure water to remove unreacted dopamine hydrochloride and byproducts to obtain a microneedle sampling layer (PT) modified with a polydopamine coating.

[0031] 4. Deposition of silver-based conductive layer: Dissolve 0.1 M silver nitrate (AgNO3) in 50 mL of deionized water to prepare silver nitrate solution; add 2 wt% dilute ammonia solution dropwise to the silver nitrate solution until the mixed solution changes from clear to turbid and then back to clear, then stop adding dilute ammonia solution to prepare silver ammonia solution; immerse the microneedle sampling layer modified with polydopamine coating obtained in step 3 into the silver ammonia solution and react magnetically at room temperature for 24 h, using the reducing property of polydopamine to reduce silver ions, thereby depositing on the surface of polydopamine coating to form a silver nanoparticle array layer; after the reaction is completed, wash the sample with ethanol and ultrapure water in sequence to remove residual silver ammonia solution, and obtain the microneedle sampling layer (APT) with deposited silver conductive layer.

[0032] 5. Construction of superhydrophobic surface: 100 μL of 1H,1H,2H,2H-perfluorodecylthiol was mixed with 40 mL of anhydrous ethanol to obtain a hydrophobic modification solution; the microneedle sampling layer with the deposited silver conductive layer obtained in step 4 was immersed in the hydrophobic modification solution and reacted for 12 h, so that 1H,1H,2H,2H-perfluorodecylthiol was bonded to the surface of the silver nanoparticle array layer through silver-sulfur bonds, introducing low surface energy perfluoroalkyl chains; after the reaction, the composite material was rinsed with deionized water and dried at room temperature to obtain a superhydrophobic microneedle patch (FAPT, hereinafter referred to as superhydrophobic microneedle patch) integrating minimally invasive blood collection and SERS blood detection functions.

[0033] II. Performance Characterization of Superhydrophobic Microneedle Patches Integrating Minimally Invasive Blood Collection and SERS Blood Detection Functions 1. Structural characterization During the fabrication of superhydrophobic microneedle patches, scanning electron microscopy was used to observe the surface morphology of the coating at different fabrication stages.

[0034] The results are as follows Figure 3 As shown, it can be seen that the microneedle sampling layer obtained in 1) has a microneedle array structure and a very smooth and flat surface. Figure 3(a)). 2) Under weakly alkaline conditions, dopamine can undergo oxidative self-polymerization to form a polydopamine coating of a certain thickness on the substrate surface; after modification with dopamine, the surface of the microneedle sampling layer becomes rougher, some nanostructures appear, and they are tightly adsorbed on the surface of the microneedle sampling layer ( Figure 3 (b) 3) Utilizing the ability of catechol groups and amino active groups on the surface of polydopamine to reduce metal ions in situ, by placing the prepared microneedle sampling layer modified with polydopamine coating into a silver ammonia solution to react and reduce the silver ammonia solution, a stable silver nanolayer is formed on the surface, and a complete conductive network is formed at the same time. The microneedle sampling layer with deposited silver conductive layer was successfully prepared, which provides a foundation for the subsequent preparation of superhydrophobic materials; it can be seen that Ag nanoparticles are distributed on the surface of the microneedle sampling layer with deposited silver conductive layer ( Figure 3 (c) 4) Utilizing the strong coordination between transition metal Ag and thiol ligands, 1H,1H,2H,2H-perfluorodecylthiol was successfully linked to the surface of the microneedle sampling layer of the deposited silver conductive layer, thereby endowing the microneedle sampling layer of the deposited silver conductive layer with a low surface energy and successfully constructing a superhydrophobic microneedle patch; after the microneedle sampling layer of the deposited silver conductive layer was modified with 1H,1H,2H,2H-perfluorodecylthiol, fluorine-containing molecules were grafted onto the surface of silver nanoparticles through Ag-S bonds. By comparing the scanning electron microscope images before and after modification ( Figure 3 (c) and Figure 3 As can be seen from (d), the surface morphology remains basically unchanged after modification.

[0035] 2. Elemental Analysis During the fabrication of superhydrophobic microneedle patches, X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition of the coatings at different fabrication stages.

[0036] The results are as follows Figure 4 As shown, it can be seen that 1) the XPS full spectrum of the microneedle sampling layer exhibits characteristic peaks of C 1s (~285 eV), N 1s (~400 eV) and O 1s (~532 eV), which are consistent with the basic elemental composition of polyurethane (C, H, O, N). Figure 4 (a) The C 1s of the microneedle sampling layer can be fitted with three characteristic peaks: the highest intensity CC peak (~284.8 eV) corresponds to the main carbon chain skeleton; the CO peak (~286.5 eV) belongs to oxygen-containing carbon structures such as ether bonds and hydroxyl groups; the C=O peak (~288.8 eV) corresponds to amide / ester carbonyl groups ( Figure 4(b)). 2) The O 1s peak of the microneedle sampling layer can be fitted as two peaks: the main peak C=O (~532.0 eV) corresponds to the carbonyl structure, and the weaker CO peak (~533.5 eV) corresponds to the ether bond and hydroxyl group. However, the XPS full spectrum of the microneedle sampling layer modified with polydopamine coating is still C1s, N 1s, and O 1s, and no new element peaks appear. Figure 4 (c) indicates that the polydopamine modification did not change the matrix element types; the C 1s of the microneedle sampling layer of the polydopamine coating can still be fitted as three peaks, with slight changes in peak intensity: CC is still the strongest peak, corresponding to the aromatic ring of polydopamine and the original carbon chain; the CO peak intensity is significantly improved, due to the large number of phenolic hydroxyl groups and ether bonds in polydopamine; the C=O peak intensity changes slightly, which is due to the superposition of the quinone structure formed by the oxidation of polydopamine and the original carbonyl group of polyurethane. Figure 4 (b) This result indicates that polydopamine has been successfully modified onto the surface of the microneedle sampling layer and introduced more oxygen-containing functional groups; the O 1s of the microneedle sampling layer modified with polydopamine coating still has two peaks, the relative proportion of the C=O main peak has slightly decreased, while the intensity of the CO peak has significantly increased, which is also attributed to the abundant phenolic hydroxyl groups and ether bond structure in polydopamine. Figure 4 (c)). 3) In addition to C, O, and N, the XPS full spectrum of the microneedle sampling layer of the deposited silver conductive layer clearly shows the 3d characteristic peaks of elemental Ag; magnification of the Ag 3d region reveals two sets of adjacent characteristic peaks with an energy difference of approximately 6 eV, consistent with the characteristic electron binding energy of metallic silver ( Figure 4 (d) This result indicates that the loaded silver exists in a zero-valent metallic state, rather than silver ions or silver oxide. This bimodal structure further confirms that silver nanoparticles have been successfully coated on the surface of the microneedle sampling layer modified with a polydopamine coating. 4) The XPS full spectrum of the superhydrophobic microneedle patch shows the addition of a characteristic F 1s (~689 eV) peak on the basis of the microneedle sampling layer with deposited silver conductive layer, along with a characteristic S element peak. The S2p binding energy is approximately 162.0 eV. Figure 4 (e) indicates that fluorine-containing molecules are grafted onto the surface of silver nanoparticles via Ag-S bonds. This result shows that 1H,1H,2H,2H-perfluorodecylthiols have been successfully grafted onto the surface of AgNPs, achieving low surface energy modification of the microneedle sampling layer surface.

[0037] 3. Hydrophobicity test 1) Superhydrophobicity assessment In the fabrication process of superhydrophobic microneedle patches, the surface hydrophilicity and hydrophobicity of the coating at different fabrication stages were characterized and evaluated using the static water contact angle method. The specific steps are as follows: The coating sample to be tested was fixed on the sample stage of the contact angle measuring instrument. The contact angle measuring instrument was turned on, and the droplet parameters were set to deionized water with a volume of 2 μL. The needle tip was controlled to release the liquid slowly and uniformly. Five non-overlapping test areas were randomly selected on the surface of the coating sample to be tested, and the static water contact angle test was performed sequentially. The droplet morphology was photographed and the contact angle value was read. After removing outliers, the average contact angle of the five valid data sets was calculated, and the hydrophilicity and hydrophobicity of the coating sample to be tested were evaluated based on the average contact angle value.

[0038] Test results are as follows Figure 5 As shown in Figure (a), the contact angles of the microneedle sampling layer, the microneedle sampling layer modified with a polydopamine coating, the microneedle sampling layer with a deposited silver conductive layer, and the superhydrophobic microneedle patch are 93.33°, 68.71°, 101.68°, and 158.28°, respectively. The superhydrophobic microneedle patch exhibits excellent superhydrophobicity.

[0039] 2) Environmental stability assessment Further evaluation of the environmental stability of the hydrophobicity of the superhydrophobic microneedle patch was conducted. The specific steps were as follows: the superhydrophobic microneedle patch was placed in a refrigerator (-26°C), a room temperature, and a 100°C oven for 24 h, respectively, and then its water contact angle was tested according to the method in step 1).

[0040] Test results are as follows Figure 5 As shown in Figure (b), it can be seen that the water contact angle of the superhydrophobic microneedle patch after different temperature treatments is greater than 150.0°, indicating that the superhydrophobic microneedle patch has excellent environmental stability.

[0041] 3) Assessment of resistance to ultraviolet aging To evaluate the anti-aging performance of the sample during use, an accelerated UV aging experiment was conducted. The specific steps are as follows: the superhydrophobic microneedle patch was placed under a UV lamp for 12 h, and then the water contact angle at different time periods was tested according to the method in step 1).

[0042] Test results are as follows Figure 5 As shown in (c), after 12 h of UV irradiation, the water contact angle of the superhydrophobic microneedle patch decreased slightly, but remained above 150.0°, which fully demonstrates that the superhydrophobic microneedle patch sample has excellent UV aging resistance.

[0043] 4) Investigation of hydrophobic patterns To further investigate the hydrophobic mode of the superhydrophobic microneedle patch, the contact angle of the superhydrophobic microneedle patch at different tilt angles was tested according to the method in step 1).

[0044] Test results are as follows Figure 5 As shown in (d), the shape of the droplet changes as the tilt angle increases (from 45° to 180°), but it remains firmly attached to the sample surface. This result demonstrates that the prepared superhydrophobic microneedle patch exhibits superhydrophobic properties similar to rose petals.

[0045] 4. Detection of blood concentration effect 4 μL of blood was dropped onto the surface of a superhydrophobic microneedle patch, and the morphological evolution of the blood droplet on the superhydrophobic microneedle patch surface over time was continuously recorded at room temperature.

[0046] Test results are as follows Figure 6 As shown, when blood is immediately added to the superhydrophobic microneedle patch (0 min), the blood droplet exhibits a full hemispherical outline on the patch surface. The contact line is stably anchored by the arrayed conical protrusions, without significant spreading. This phenomenon directly demonstrates the hydrophobic properties of the surface modified with 1H,1H,2H,2H-perfluorodecylthiol, effectively inhibiting liquid wetting and diffusion. Between 2 and 4 min, the droplet begins to slowly shrink due to water evaporation, slightly reducing its volume. However, the contact line remains firmly fixed by the arrayed conical protrusions, demonstrating the pinning effect of the conical protrusions on the contact line, preventing analyte dilution caused by droplet slippage or spreading. The fact that the contact line remains fixed by the conical protrusions and the droplet shape remains symmetrical indicates that the hydrophobic interface effectively resists water spreading and penetration. Between 4 and 8 min, the blood continues to concentrate, and the droplet volume further decreases. Between 8 and 12 minutes, the blood droplets contracted rapidly, their volume further decreased, and they converged from the edges to the center. The "pinning" effect of the arrayed conical protrusions maintained the contact line position, preventing droplet diffusion. At 30 minutes, the blood droplet volume decreased significantly, but it still maintained a compact hemispherical shape, without drying, spreading, or substrate wetting. This indicates that the hydrophobic interface remained stable during the long-term evaporation of the droplets, continuously providing a confined concentration space for the target molecules. These results demonstrate that the superhydrophobic microneedle patch achieves efficient concentration of blood droplets through the synergistic effect of the hydrophobic coating and the arrayed conical protrusions: the hydrophobic interface inhibits liquid spreading, and the arrayed conical protrusions anchor the contact line, ultimately enriching trace target molecules in the SERS "hotspot" region of the Ag nanoparticles on the surface, laying a solid foundation for subsequent high-sensitivity SERS detection.

[0047] III. Blood Substance Detection Using Superhydrophobic Microneedle Patches Integrating Minimally Invasive Blood Collection and SERS Blood Detection Functions 1. Minimally invasive sampling: The skin of the subject's fingertip is gently pressed against the microneedle array structure of the superhydrophobic microneedle patch prepared in step one, with a pressure of 5~10 N and a time of 5~10 s, to collect 3 μL of whole blood, which is then mixed in an anticoagulant tube. 2. Raman Detection: A portable Raman spectrometer (laser power 50 mW, integration time 10 s) with an excitation wavelength of 532 nm was used to detect the collected whole blood samples, ranging from 600 to 2000 cm⁻¹. -1 Spectroscopy, through the comparison of characteristic peaks, enables qualitative analysis of blood.

[0048] Table 1. Analysis of blood substances corresponding to Raman spectroscopy.

[0049]

[0050] Test results as follows Figure 7 As shown in Table 1, after human blood was mixed in an anticoagulant tube, Raman spectra measured under 532 nm excitation light showed characteristic peaks at multiple positions. These peaks correspond to various vibrational modes of biomolecules in the blood. The peak at 676 cm⁻¹ is a prime example. -1 The peak originates from the pyrrole respiration vibration of the heme groups in hemoglobin. 758 cm⁻¹ -1 The peak originates from the deformation vibration of heme pyrrole. 997 cm⁻¹ -1 The peak originates from the phenylalanine loop respiration pattern in the protein. 1132 cm⁻¹ -1 The peak is related to the CO stretching vibration of glucose or the vibration of heme. 1173 cm⁻¹ -1 The peak corresponds to the tyrosine vibrational mode. 1225 cm⁻¹ -1 The peak belongs to the skeletal vibration of protein amide III. 1304 cm⁻¹ -1 The peak is correlated with the CH deformation vibration of lipids or proteins. 1343 cm⁻¹ -1 The peak originates from the symmetrical stretching vibration of the heme pyrrole semi-ring. 1376 cm⁻¹ -1 The peak is attributed to the stretching vibration of heme pyrrole. 1587 cm⁻¹ -1 The peak represents the C=C vibration of the heme porphyrin ring. 1639 cm⁻¹ -1 The peaks originate from the C=C vibration of heme or the amide I band of proteins. These peaks collectively reveal the dominant contribution of hemoglobin in the blood, while also reflecting the presence of components such as blood glucose and proteins.

[0051] IV. Stability Evaluation of Superhydrophobic Microneedle Patches Integrating Minimally Invasive Blood Collection and SERS Blood Detection Functions Referring to the method in step three, superhydrophobic microneedle patches were used to detect blood substances, and the tests were repeated 20 times at different locations on different blood samples.

[0052] The results are shown in Figure 8. From the single spectrum in Figure 8(a), it can be seen that the signal intensities of the three different blood samples (1, 2, and 3) are slightly different, further indicating that the SERS platform can achieve a sensitive response to the concentration of target molecules in blood, providing reliable technical support for non-invasive blood biochemical analysis. Figures 8(b), (c), and (d) show the SERS spectra of blood samples 1, 2, and 3 after 20 repeated tests at different locations. It can be observed that the peak positions and shapes of each spectral line are highly overlapping, with no obvious peak shift, although the intensity varies slightly. This may be due to the continuous concentration of blood droplets during the test. This proves that the Ag nanoparticles on the surface of the superhydrophobic microneedle patch are uniformly distributed, and the hydrophobic coating is stable, maintaining long-term stability of its structure and chemical properties during multiple tests.

[0053] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions, characterized in that, It includes a microneedle sampling layer, the surface of which is sequentially coated with a polydopamine coating, a silver nanoparticle array layer and a hydrophobic protective layer; The microneedle sampling layer is composed of a thermoplastic polyurethane integrally molded substrate and an array of conical protrusions grown on the substrate.

2. The superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions according to claim 1, characterized in that, The hydrophobic protective layer is a superhydrophobic coating formed by modification with 1H,1H,2H,2H-perfluorodecylthiol.

3. The method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions as described in claim 1 or 2, characterized in that, A thermoplastic polyurethane solution is injected into a microneedle mold to obtain a microneedle sampling layer. A polydopamine coating is formed on the surface of the microneedle sampling layer by dopamine self-polymerization. Silver nanoparticles are deposited on the surface of the polydopamine coating to form a silver nanoparticle array layer. A hydrophobic protective layer is prepared on the surface of the silver nanoparticle array layer to obtain a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions.

4. The method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions according to claim 3, characterized in that, The thermoplastic polyurethane solution is formed by mixing thermoplastic polyurethane with N,N-dimethylformamide.

5. The method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions according to claim 3, characterized in that, Silver nanoparticles were deposited on the surface of a polydopamine coating using a chemical reduction method to form a silver nanoparticle array layer.

6. The method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions according to claim 5, characterized in that, Dilute ammonia solution was added dropwise to silver nitrate solution to obtain silver ammonia solution; a microneedle sampling layer modified with polydopamine coating was immersed in silver ammonia solution to achieve the deposition of silver nanoparticles.

7. The method for preparing a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions according to claim 3, characterized in that, A hydrophobic protective layer was prepared on the surface of the silver nanoparticle array layer by vapor treatment with 1H,1H,2H,2H-perfluorodecylthiol, resulting in a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions.

8. The application of the superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions as described in claim 1 or 2 in blood testing.

9. A method for detecting blood substances using a superhydrophobic microneedle patch integrating minimally invasive blood collection and SERS blood detection functions as described in claim 1 or 2, characterized in that, Capillary whole blood is collected by an array of conical protrusions on a superhydrophobic microneedle patch that integrates minimally invasive blood collection and SERS blood detection functions. Then, Raman spectroscopy is used to detect the collected capillary whole blood. Qualitative analysis is achieved by comparing characteristic peaks to obtain the detection results of the substances to be tested in the blood.

10. The method according to claim 9, characterized in that, The detection was performed under the condition of an excitation wavelength of 532 nm.

Images