Photosensitizer, suture line comprising same and preparation method of suture line

Abstract

The invention belongs to the field of suture lines, and particularly discloses a photosensitizer, a suture line comprising the photosensitizer and a preparation method of the suture line. The photosensitizer comprises a conjugated polymer and is loaded on the surface of the suture line, so that the suture line has good antibacterial performance and a good fluorescence labeling function to realize fluorescence imaging and real-time monitoring.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of sutures, in particular to a photosensitizer, sutures comprising the same and methods of making the same. BACKGROUND

[0002] Sutures are widely used in various aspects of clinical surgery, playing a crucial role in promoting wound healing. Currently, various types of sutures have been developed, from metal wires to animal and plant fibers (such as silk, linen, human hair, and sheep or goat intestines), as well as synthetic fibers made of artificially synthesized non-absorbable polymers (such as nylon, polypropylene) and absorbable polymers (such as polyglycolic acid, polylactic acid and their copolymer PGLA). Due to the adhesion and infiltration of bacteria at the surgical site, subsequent surgical site infections (SSI) have become a common complication of suturing. Unfortunately, most of the sutures currently used have limited effectiveness in preventing SSI, and the only antibacterial suture is Coated VICRYL Plus antibacterial suture based on triclosan produced by Johnson & Johnson. Clinical feedback shows that this special suture can effectively prevent bacterial colonization and reduce the risk of SSI, however, triclosan has many negative effects, such as bacterial resistance, disruption of hormone secretion and potential risk associated with cancer.

[0003] Therefore, there are currently a large number of studies aimed at developing antibacterial sutures by incorporating antibiotics, metal antibacterial agents and other antibacterial materials into sutures. However, challenges such as drug resistance and cytotoxicity still exist, which hinder the development of effective antibacterial sutures. In addition to preventing infection, it is crucial to monitor the integrity of sutures in real time in a clinical environment, especially when sutures are used in hidden areas such as subcutaneous tissue. Because the rupture of sutures in these areas can cause serious complications such as peritonitis and hemorrhage. At the same time, monitoring the status of sutures helps doctors predict the degree of wound healing. However, due to the lack of traceability of sutures, there are still few reports on the use of visible light to monitor the status of subcutaneous wound sutures.

[0004] At present, in vivo imaging technology enables researchers to directly monitor the cell activity and gene behavior of living organisms. Due to its simple operation, intuitive results and high sensitivity, the technology has been widely used in the fields of life science, medical research and drug development. In recent years, photodynamic therapy (PDT) is one of the in vivo imaging technologies that has attracted more and more attention from researchers. Photodynamic therapy involves the use of a photosensitizer molecule, such as a conjugated polymer photosensitizer, which, when activated by a specific wavelength of light, produces reactive oxygen species (ROS) to kill bacteria, fungi and other microorganisms without causing cytotoxicity or drug resistance. In addition, it can also emit visible light, so that the location and state of the photosensitizer can be monitored. Today, photodynamic therapy has been applied in many fields such as wound care, oral medicine, dermatology, etc. Conjugated polymer photosensitizers have been widely studied in solution sterilization or in vivo infection treatment, but there are few studies on conjugated polymer photosensitizers as antibacterial surface materials, and even fewer studies in the field of suture surface antibacterial. SUMMARY

[0005] In view of the defects of the prior art that the photosensitizer on the suture is not firmly loaded, and the photosensitivity and antibacterial effects are poor, the present application provides a photosensitizer, a suture comprising the same, and a preparation method and application thereof.

[0006] To achieve the above-mentioned purpose, the specific technical solutions include the following:

[0007] In one aspect, the present application provides a photosensitizer comprising a conjugated polymer, the conjugated polymer comprising a poly4,6-diyne sebacic acid backbone and a plurality of side chains on the poly4,6-diyne sebacic acid backbone, at least one of the side chains comprising a [CH(CH3)2]2N(CH2)2NH- group, the side chain comprising the [CH(CH3)2]2N(CH2)2NH- group being grafted to the poly4,6-diyne sebacic acid backbone by an amide bond.

[0008] The above-mentioned conjugated polymer (referred to as DPA-PDDA) of the present application is based on a poly4,6-diyne sebacic acid (PDDA) basic skeleton, and a positively charged N,N-diisopropylethylenediamine (DPA) group is grafted on the side chain of PDDA. It is a positively charged conjugated polymer, which has the characteristics of realizing fluorescence imaging by emitting fluorescence, high photodynamic sterilization efficiency, good biocompatibility and biological safety.

[0009] Preferably, the conjugated polymer is obtained by reacting poly4,6-diyne sebacic acid with N,N-diisopropylethylenediamine.

[0010] Preferably, the number average molecular weight of the poly-4,6-diyne sebacic acid is 5000-50000 Da, and can be 5000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000 Da, etc., and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be exhaustive listing of specific point values included in the range.

[0011] Further preferably, the grafting rate of the N,N-diisopropylethylamine group in the conjugated polymer is 10%-95%, more preferably 55%-70%, and more specifically can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, etc., and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be exhaustive listing of specific point values included in the range. Nuclear magnetic resonance is used to test the grafting rate of the N,N-diisopropylethylamine group in the conjugated polymer.

[0012] In a second aspect, the present application provides a suture, comprising a suture base and the photosensitizer loaded on the surface of the suture base, wherein the photosensitizer comprises the conjugated polymer.

[0013] The positively charged conjugated polymer described above is used as a photosensitizer in a suture, and is uniformly and firmly adsorbed on the surface of the suture by electrostatic adsorption, which endows the suture with good fluorescent labeling function to realize fluorescent imaging, good antibacterial performance and good biocompatibility, so that the suture can realize the removal of adherent bacteria and biofilm, and real-time fluorescent monitoring of the suture in surgery by the naked eye.

[0014] Preferably, in the suture, the loading amount of the conjugated polymer loaded on the surface is 20-140 ng / cm 2 , and can be 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130 ng / cm 2 , etc., and specific point values between the above-mentioned point values, limited to the length and for the sake of simplicity, the present application will not be exhaustive listing of specific point values included in the range.

[0015] The method for testing the loading of the conjugated polymer is as follows: Under light-protected conditions, an etched wire substrate with a surface area of ​​S is immersed in an aqueous solution containing M0 units of conjugated polymer. After immersion, the etched wire substrate and the post-immersion solution are obtained. The etched wire substrate is then washed with water and dried sequentially to obtain the suture and the post-wash solution. The post-immersion solution and the post-wash solution are combined and then freeze-dried to obtain M1 units of conjugated polymer. The surface area S of the etched wire substrate is calculated from its diameter and length. The loading of the conjugated polymer (ng / cm²) is also measured. 2 ) = (M0-M1) / S.

[0016] Preferably, the average diameter of the wire substrate is 0.01-1.3 mm, more preferably 0.1-1.2 mm, and can specifically be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 mm, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0017] Preferably, the material of the wire matrix includes polylactic acid (PLA).

[0018] Preferably, the polylactic acid has a number average molecular weight of 10,000 Da-160,000 Da, more preferably 81,000 Da-145,000 Da, and more specifically, it can be 10,000, 30,000, 50,000, 70,000, 90,000, 110,000, 130,000, 150,000, 160,000 Da, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0019] Using polystyrene with a known molecular weight as a reference, and with 5% chloroform and 95% tetrahydrofuran as mobile phases, the number-average molecular weight of polylactic acid was determined by gel permeation chromatography (GPC) under a 2414RI (refractive index) detector.

[0020] Thirdly, the present invention provides a method for preparing the aforementioned suture, comprising the following steps:

[0021] S1. Poly(4,6-diyne-decanedioic acid), N,N-diisopropylethylenediamine, sodium N-hydroxysuccinimide sulfonate and 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added to 2-morpholine ethanesulfonic acid buffer solution and reacted. The mixture was then dialyzed and lyophilized to obtain the conjugated polymer.

[0022] S2. The base material of the suture thread is obtained by melt spinning;

[0023] S3. The suture substrate is plasma etched; under light-protected conditions, the etched suture substrate is immersed in a solution containing the conjugated polymer, and then washed and dried sequentially to obtain the suture.

[0024] Preferably, in step S1, the molar ratio of poly(4,6-diyne-decanoic acid) and N,N-diisopropylethylenediamine is 1:(0.2-30).

[0025] Preferably, in step S1, the molar ratio of poly(4,6-diyne sebacic acid), sodium N-hydroxysuccinimide sulfonate and 1-ethyl-(3-dimethylaminopropyl)carbodiimide is 1:(1-2):(5-15).

[0026] Preferably, in step S1, the concentration of 2-morpholine ethanesulfonic acid in the 2-morpholine ethanesulfonic acid buffer is 0.5-2 mol / L.

[0027] Preferably, in step S1, the reaction time is 6-48 hours.

[0028] Preferably, in step S2, the temperature of the melt spinning is 170-220°C.

[0029] Preferably, in step S3, the plasma etching time is 2-15 minutes.

[0030] Preferably, in step S3, the soaking time is 1-24 hours.

[0031] Preferably, in step S3, the concentration of the conjugated polymer in the solution containing the conjugated polymer is 0.2-20 mg / mL.

[0032] Preferably, in step S3, the drying temperature is 35-45°C.

[0033] Compared with the prior art, the present invention has the following beneficial effects: the suture surface of the present invention is uniformly and firmly loaded with a positively charged conjugated polymer DPA-PDDA photosensitizer, which gives the suture a good fluorescent labeling function to achieve fluorescence imaging and good antibacterial properties, so that the suture can remove adhering bacteria and biofilms, and the suture can be monitored for fluorescence in real time by the naked eye during surgery. Attached Figure Description

[0034] Figure 1 The synthetic route of DPA-PDDA of this invention involves grafting DPA onto the carboxyl group on the side chain of PDDA. Figure 1 The DPA-PDDA structure in the product only represents one of the grafting possibilities.

[0035] Figure 2 This is the 1H NMR spectrum of PDDA, with D2O as the solvent used in the test.

[0036] Figure 3 The NMR spectrum of DPA-PDDA with a grafting rate of 95% is shown in the form of 1H NMR, with D2O as the solvent used in the test.

[0037] Figure 4 The NMR spectrum of DPA-PDDA with a grafting rate of 70% is shown in the form of 1H NMR, with D2O as the solvent used in the test.

[0038] Figure 5 The 1H NMR spectrum of DPA-PDDA with a grafting rate of 55% is shown, with D2O as the solvent used in the test. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of the present invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, all raw materials used in the embodiments and comparative examples of the present invention are commercially available, and the same raw materials were used in all parallel experiments.

[0040] (1) PLA:

[0041] PLA-1: PLAFY802, molecular weight 145000Da, purchased from Anhui Fengyuan Biotechnology Co., Ltd.

[0042] PLA-2: PLA FY601, molecular weight 106000Da, purchased from Anhui Fengyuan Biotechnology Co., Ltd.

[0043] PLA-3: PLA FY201, molecular weight 81000Da, purchased from Anhui Fengyuan Biotechnology Co., Ltd.

[0044] PLA suture spinning process: PLA is used as raw material, and a 28:1 single-screw extruder is used. The temperatures of each zone of the extruder are set to 215℃, 210℃, 210℃, 195℃, and 175℃; the hot drawing temperature is 100℃. In addition, PLA monofilaments of different diameters are obtained by adjusting the spinneret orifice diameter, the metering pump, and the draw ratio.

[0045] (2) PDDA:

[0046] PDDA-A: Polymerization temperature is 100℃, and the molecular weight detected by electrophoresis is 5000 Da;

[0047] PDDA-B: Polymerization temperature is 120℃, and the molecular weight detected by electrophoresis is 20000 Da;

[0048] PDDA-C: Polymerization temperature is 140℃, and the molecular weight detected by electrophoresis is 50,000 Da;

[0049] Different molecular weights of PDDA are obtained by controlling the polymerization temperature. The specific synthesis process is as follows:

[0050] 4-Pentyn-1-ol (476 mmol) was dissolved in 30 g of acetone and reacted with CuCl (1.41 mmol) and tetramethylethylenediamine (TMEDA, 2.41 mmol) as catalysts under oxygen-purified and stirred conditions at room temperature for 6 hours. After the reaction was complete, the reaction mixture was removed by rotary evaporation under vacuum to remove all acetone. 100 mL of ethyl acetate was added to dissolve the acetone, and most of the catalysts CuCl and TMEDA were removed by repeated small extractions with saturated brine.

[0051] The product was further purified by silica gel column chromatography, using a mixture of dichloromethane and ethyl acetate as eluent. The solvent was collected and evaporated under vacuum to obtain a white crystalline solid, 4,6-diynyldecanediol (C10-OH). 1 ¹H NMR analysis showed a purity of ≥99.5%.

[0052] Dissolve 3.8 g of C10-OH in 50 g of acetone and place the solution in a nested reaction flask with circulating water. Add 20 mL of freshly prepared 2.672 mol / L acetone dropwise under low temperature and stirring conditions (4°C, circulating water). -1 Jones' reagent (26.72 g chromium trioxide, 23 mL concentrated sulfuric acid, diluted to 100 mL with deionized water). The circulating water was removed, and the reaction continued at room temperature for 24 h. The reaction was stopped by adding an appropriate amount of isopropanol, and the blue-green chromium salt solid was removed by filtration through filter paper at normal pressure. The ethyl acetate phase was collected by extraction with ethyl acetate and acid-base. The product was further purified by silica gel column chromatography, using a mixture of dichloromethane and ethyl acetate as the eluent. The solvent was collected and evaporated under vacuum to give a white solid of 4,6-diyne-decanedioic acid (DDA). 1 The purity was determined to be approximately 97% by ¹H NMR.

[0053] 4-Methylaminopyridine (4.54 g, 42 mmol) was dissolved in 15 mL of acetone, and diethyl oxalate (2.92 g, 21 mmol) was added dropwise under stirring at room temperature. After reacting for 10 hours, the solvent was removed under vacuum. 60 mL of methanol was added to the remaining solid and heated until dissolved. The solid was then volatilized and crystallized at room temperature in the dark. The crystals were rinsed with methanol pre-cooled to 4 °C to remove colored impurities, and dried under vacuum to obtain a white needle-like solid, N,N'-bis(pyridin-4-methyl)oxalamide (M4).

[0054] Weigh 1 g of DDA (5.15 mmol) and dissolve it in 250 mL of methanol. Dissolve 1.392 g of ligand M4 (5.15 mmol) in 250 mL of methanol. After thoroughly mixing the DDA and M4 methanol solutions, place them in a glass crystallizing dish and allow them to evaporate and crystallize at room temperature in the dark. Needle-shaped eutectic crystals slowly grow over approximately one week. Place the eutectic crystals in a vacuum oven, evacuate to a vacuum level less than 0.1 MPa, and heat to 100-140 °C (100 °C prepares PDDA-A, 120 °C prepares PDDA-B, and 140 °C prepares PDDA-C). Maintain this temperature for 12 hours, then turn off the heating and allow the mixture to return to room temperature and then to atmospheric pressure. Transfer the solid from the crystallizing dish to 400 mL of 1 g L... -1 The PDDA solid was dissolved in NaOH aqueous solution by thorough stirring. The solution was filtered through a sintered glass funnel at normal pressure, and the filtrate was collected. Dilute hydrochloric acid was slowly added dropwise to the filtrate until the red PDDA solid particles were completely precipitated. One-third of the volume of methanol was added to the filtrate, and the mixture was stirred thoroughly for 5 minutes. The solution was then filtered through filter paper at normal pressure, and the PDDA solid was collected. Finally, the collected PDDA solid was washed with a small amount of methanol and filtered to form flakes, which were then dried in a vacuum drying oven. PDDA-A, PDDA-B, and PDDA-C were obtained, respectively.

[0055] The molecular weight of PDDA was determined using agarose gel electrophoresis (AGE). AGE was performed using a DYCP-31DN horizontal electrophoresis system. A 3.5% (w / w) agarose gel containing the nucleic acid dye Gelred was used, with 1×TAE buffer, at 150V for 45 min. Molecular weight calibration was performed using a DNA marker, D2000 Plus (5000–100 bp, molecular weight range 3250–65.0 kDa) and a 10 bp DNA Ladder (150–10 bp, molecular weight range 97.5–6.5 kDa). After electrophoresis, the agarose gel was first imaged with fluorescence using the ChemiDoc XRS+System, and then soaked in 1% (v / v) hydrochloric acid solution for 1 hour until the PDDA bands turned red before photographing. The color signal intensity and migration distance of the PDDA bands were extracted using ImageJ 1.51 J8 software.

[0056] (3) DPA-PDDA:

[0057] The preparation method of DPA-PDDA includes the following steps:

[0058] Synthesis of DPA-PDDA:

[0059] 100 mg PDDA (1 eq) was reacted with 148.7 mg–1487 mg N,N-diisopropylethylenediamine (DPA, 0.2–30 eq) in 0.1 M 2-morpholine ethanesulfonic acid buffer at pH 7.1 for 24 h in the presence of sodium N-hydroxysuccinimide sulfonate (NHS, 1.5 eq) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC, 10 eq) as catalysts. The small molecules were then removed by dialyzing in pure water, and the resulting product was lyophilized to obtain DPA-PDDA. The synthetic route is as follows: Figure 1 As shown.

[0060] Characterization of PDDA and DPA-PDDA:

[0061] 2 mg of lyophilized PDDA and DPA-PDDA were weighed and dissolved in D2O, and then subjected to proton nuclear magnetic resonance spectroscopy. Some test results are shown below. Figure 2 As shown; the grafting rate of DPA in DPA-PDDA can be calculated by NMR integration, and the grafting rate of DPA (%) = molar amount of DPA group / initial molar amount of carboxyl group in PDDA side chain × 100%.

[0062] The grafting rate of DPA can be adjusted by changing the molar ratio of PDDA and N,N-diisopropylethylenediamine in the reactants. Due to electrostatic repulsion and steric hindrance, the grafting rate of DPA is difficult to achieve 100%, but it can approach 100% by adding an excess of DPA. For convenient preparation, stable positively charged DPA, and good antibacterial effect, the grafting rate is controlled between 55% and 95%. The DPA is named according to its grafting rate; for example, 10% DPA-PDDA represents a grafting rate of 10%, and 70% DPA-PDDA represents a grafting rate of 70%.

[0063] The specific molar ratio of PDDA to N,N-diisopropylethylenediamine in the preparation of DPA-PDDA with different DPA grafting rates is shown in Table 1.

[0064] Table 1

[0065]

[0066] The aforementioned sodium N-hydroxysuccinimide sulfonate (NHS), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC), 2-morpholinoethanesulfonic acid (MES), and N,N-diisopropylethylenediamine (DPA) are all commercially available.

[0067] (3) The methicillin-resistant Staphylococcus aureus (ATCC 6538P) and Escherichia coli (ATCC 8739) used in the following antimicrobial tests were obtained from the Guangdong Provincial Microbial Culture Collection Center.

[0068] Examples 1-9

[0069] A suture, the preparation method of which includes the following steps:

[0070] S1. Preparation of PLA sutures: Pre-dried PLA slices were poured into a 28:1 single-screw extruder for sequential spinning and hot drawing to obtain suture matrix of corresponding size; wherein, the spinning temperature of each zone was 215℃, 210℃, 210℃, 195℃, and 175℃, and the hot drawing temperature was 100℃. By adjusting the die diameter range, metering pump, and drawing process, 0.2mm monofilament PLA sutures were prepared.

[0071] Preparation of S2, DPA-PDDA-PLA sutures:

[0072] The PLA suture was etched in an oxygen plasma cleaner for 5 minutes to improve the negative charge on the surface.

[0073] Dissolve 0.2-20 mg DPA-PDDA in 1 L of deionized water to obtain DPA-PDDA aqueous solutions of different concentrations; immerse PLA sutures that have undergone plasma etching in DPA-PDDA aqueous solutions of different concentrations and incubate at 23°C in the dark for 2 h; then rinse the DPA-PDDA-PLA sutures with deionized water several times until the rinsing solution becomes colorless; place the rinsed DPA-PDDA-PLA sutures in a vacuum drying oven at 37°C and dry for 24 h.

[0074] By weighing the DPA-PDDA aqueous solution and washing solution before and after freeze-drying incubation, the mass loss of DPA-PDDA can be measured. The total mass of DPA-PDDA loaded on the suture surface can then be calculated. Furthermore, the DPA-PDDA loading amount (ng / cm²) on the suture surface can be calculated based on the suture surface area. 2 ).

[0075] By adjusting the concentration of the DPA-PDDA aqueous solution, sutures with different surface-loaded DPA-PDDA levels can be prepared. Table 2 shows the different DPA-PDDA types, PLA types, and DPA aqueous solution concentrations used in Examples 1-9.

[0076] Comparative Example 1

[0077] Compared with Example 2, this comparative example uses the 0.2mm monofilament PLA-2 suture from step S1 for subsequent antibacterial performance testing, and does not perform step S2.

[0078] Comparative Example 2

[0079] Compared with Example 2, this comparative example directly used PDDA to treat 0.2mm monofilament PLA-2 sutures. The specific steps are as follows.

[0080] A suture, the preparation method of which includes the following steps:

[0081] Preparation of S1 PLA sutures: Pre-dried PLA-2 chips were poured into a 28:1 single-screw extruder for sequential spinning and hot drawing to obtain suture matrix of corresponding size; wherein, the spinning temperature of each zone was 215℃, 210℃, 210℃, 195℃, and 175℃, and the hot drawing temperature was 100℃. By adjusting the die diameter range, metering pump, and drawing process, 0.2mm monofilament PLA-2 sutures were prepared.

[0082] Preparation of S2 and PDDA-PLA sutures:

[0083] The PLA-2 suture was etched in a plasma cleaner for 5 minutes to improve the negative charge on the surface.

[0084] Dissolve 2g of PDDA-B in 1L of deionized water to obtain a PDDA-B aqueous solution with a concentration of 2g / L. Immerse the plasma-etched PLA-2 sutures in the 2g / L PDDA-B aqueous solution and incubate at 23°C in the dark for 2 hours. Then rinse the PDDA-B-stained sutures with deionized water several times until the rinsing solution becomes colorless. Place the rinsed PDDA-PLA sutures in a vacuum drying oven at 37°C and dry for 24 hours.

[0085] By weighing the PDDA-B aqueous solution and washing solution before and after freeze-drying incubation, the mass loss of PDDA-B can be measured. The total mass of PDDA-B loaded on the suture surface can then be calculated. Furthermore, the PDDA-B loading amount (ng / cm²) on the suture surface can be calculated based on the suture surface area. 2 ).

[0086] Comparative Example 3

[0087] Compared to Example 2, this comparative example directly used DPA to treat 0.2mm monofilament PLA-2 sutures. The specific steps are as follows.

[0088] A suture, the preparation method of which includes the following steps:

[0089] S1, Preparation of PLA sutures: Pre-dried PLA-2 chips were poured into a single-screw extruder and the spinning temperature in each zone was 215, 210, 210, 195, and 175℃. By adjusting the die diameter range, metering pump, and drawing process, 0.2mm monofilament PLA-2 sutures were prepared.

[0090] Preparation of S2 and DPA-PLA sutures:

[0091] The PLA-2 suture was etched in a plasma cleaner for 5 minutes to improve the negative charge on the surface.

[0092] Dissolve 2g of DPA in 1L of deionized water to make a 2g / L DPA aqueous solution; immerse the plasma-etched PLA-2 suture in the 2g / L DPA aqueous solution and incubate at 23°C in the dark for 2 hours; then rinse the DPA-stained suture with deionized water several times until the rinsing solution becomes colorless; place the rinsed DPA-PLA suture in a vacuum drying oven at 37°C and dry for 24 hours.

[0093] By weighing the DPA aqueous solution and washing solution before and after freeze-drying incubation, the mass loss of DPA can be measured, and the total mass of DPA loaded on the suture surface can be calculated. Furthermore, the DPA loading amount (ng / cm²) on the suture surface can be calculated based on the suture surface area. 2 ).

[0094] Table 2

[0095]

[0096] As shown in Table 2, with the increase of DPA grafting rate in DPA-PDDA, the adsorption capacity of DPA-PDDA on the PLA suture matrix surface also increases. Compared with PDDA, DPA-PDDA has a stronger adsorption capacity on the PLA suture surface, making it easier to load onto the suture matrix. The final photosensitizer loading on the suture is significantly increased, and the photosensitizer loading is basically unaffected by the molecular weight of the PLA suture matrix.

[0097] Antibacterial performance test:

[0098] (1) Methods for antibacterial tests of PDDA and DPA-PDDA: To examine the antibacterial activity of PDDA and DPA-PDDA, bacterial suspensions (1×10⁻⁶) were prepared. 6 (CFU / mL) was mixed with PDDA and DPA-PDDA. The sample was incubated at 37°C in the dark for 30 minutes under white light (50mW / cm²). 2 The system was treated for 30 minutes. The bacterial suspension was then diluted and plated on agar plates. Antimicrobial activity was determined by counting the number of colonies on the agar plates.

[0099] (2) Method for antibacterial test of sutures: To examine the antibacterial properties of sutures, a 10 cm long suture was placed in a 24-well plate, and 10 μL of bacterial suspension (1×10⁻⁶) was dropped onto its surface. 6 CFU / mL). Incubate the sample in the dark at 37°C for 30 minutes, or incubate in the dark for 30 minutes followed by exposure to white light (50 mW / cm²). 2 Irradiate for 10 or 20 minutes. Then, dilute the bacterial suspension and spread it onto agar plates. The antibacterial activity of the suture is determined by counting the number of colonies on the agar plates.

[0100] Antibacterial activity was evaluated by inhibition rate, and the calculation formula is as follows: Inhibition rate = [1 - (number of colonies in the administration group (i.e., the antibacterial agent) / number of colonies in the blank group)] × 100.

[0101] (3) The sutures from Examples 1-9 were soaked in PBS buffer solution for 30 days. The sutures before and after soaking were excited with a light source of approximately 450-490 nm. Bright fluorescence signals were observed in the 530-590 nm channel of a fluorescence imaging device. It is evident that the DPA-PDDA of this invention, as a photosensitizer for sutures, can be relatively firmly loaded onto the sutures and exhibits good fluorescence photosensitivity, enabling the sutures to have excellent fluorescent labeling function for achieving fluorescence imaging and real-time monitoring.

[0102] Table 3

[0103]

[0104]

[0105] PDDA, due to its carboxyl-containing side chains, carries a negative charge and therefore does not adhere to negatively charged bacteria, thus exhibiting no antibacterial effect. DPA-PDDA, however, demonstrates good photodynamic bactericidal effects against Staphylococcus aureus and Escherichia coli, exhibiting broad-spectrum photodynamic bactericidal activity. Furthermore, with increasing DPA grafting rate, the zeta potential of DPA-PDDA gradually increases, enhancing its positive charge and bacterial adhesion, leading to a higher antibacterial rate under light. 70% DPA-PDDA (DPA-PDDA-4) even exhibits some antibacterial effect in the dark, while under light conditions, the generation of ROS through photodynamic therapy significantly enhances its bactericidal ability.

[0106] Table 4

[0107]

[0108] As shown in Table 4, after loading DPA-PDDA onto the suture substrate, the suture exhibits excellent antibacterial properties, enabling it to remove adhering bacteria and biofilms. Furthermore, real-time fluorescence monitoring of the suture during surgery can be achieved using a fluorescence imaging device.

[0109] Based on the analysis of Comparative Example 2 and Example 2, PDDA is negatively charged and has difficulty adsorbing onto PLA sutures. Therefore, the antibacterial effect of the product obtained by impregnating the suture matrix with PDDA is low.

[0110] Examples 1-7 show that when the DPA grafting rate is low, the adsorption capacity of DPA-PDDA on the PLA suture surface is also weak. As the DPA grafting rate increases, the adsorption capacity of DPA-PDDA on the PLA suture surface is enhanced. With the increase of the DPA grafting rate and the DPA-PDDA loading on the PLA suture surface, the photodynamic antibacterial ability is enhanced.

[0111] As shown in Examples 3 and 7, the DPA grafting rate in DPA-PDDA reaches over 70%, and the loading amount of DPA-PDDA on the suture surface is over 100 ng / cm². 2 When the above conditions are met, PLA sutures exhibit excellent photodynamic antibacterial ability, and even have a certain antibacterial ability under dark conditions.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A photosensitizer, characterized in that, The conjugated polymer includes a poly(4,6-diyne-decanedioic acid) backbone and a plurality of side chains located on the poly(4,6-diyne-decanedioic acid) backbone, at least one of the side chains including a [CH(CH3)2]2N(CH2)2NH- group, the side chain including the [CH(CH3)2]2N(CH2)2NH- group being grafted onto the poly(4,6-diyne-decanedioic acid) backbone via an amide bond.

2. The photosensitizer as described in claim 1, characterized in that, The conjugated polymer is obtained by reacting poly(4,6-diyne-decanedioic acid) with N,N-diisopropylethylenediamine. Preferably, the number-average molecular weight of the poly(4,6-diyne-decanedioic acid) is 5000-50000 Da, as determined by agarose gel electrophoresis.

3. The photosensitizer as described in claim 2, characterized in that, The grafting rate of the N,N-diisopropylethylenediamine group is 10%-95%.

4. A suture, characterized in that, The invention comprises a linear matrix and a photosensitizer according to any one of claims 1-3 loaded on the surface of the linear matrix, wherein the photosensitizer comprises the conjugated polymer.

5. The suture as described in claim 4, characterized in that, The loading amount of the conjugated polymer on the suture surface is 20-140 ng / cm. 2 .

6. The suture as described in claim 4, characterized in that, The average diameter of the wire matrix is ​​0.01-1.3 mm.

7. The suture as described in claim 4, characterized in that, The material of the wire matrix includes polylactic acid.

8. The suture as described in claim 7, characterized in that, The polylactic acid has a number-average molecular weight of 10,000 Da to 160,000 Da.

9. A method for preparing the suture according to any one of claims 4-8, characterized in that, Includes the following steps: S1. Poly(4,6-diyne-decanedioic acid), N,N-diisopropylethylenediamine, sodium N-hydroxysuccinimide sulfonate and 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added to 2-morpholine ethanesulfonic acid buffer solution and reacted. The mixture was then dialyzed and lyophilized to obtain the conjugated polymer. S2. The base material of the suture thread is obtained by melt spinning; S3. The line substrate is plasma etched; Under light-protected conditions, the etched suture substrate is immersed in a solution containing the conjugated polymer, and then washed and dried sequentially to obtain the suture.

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