A method and dispersion liquid for cellulose nanofiber-assisted dispersion of hydroxyapatite nanowires

Abstract

The present invention discloses a method and dispersion liquid for dispersing hydroxyapatite nanowires using cellulose nanofibers as an auxiliary agent. This method utilizes cellulose nanofibers, a rich natural biomass resource, as a dispersant for the hydroxyapatite nanowires. Through a simple mixing and ultrasonic process, the hydroxyapatite nanowires are efficiently dispersed in an aqueous solution. This method conveniently and quickly produces a naturally non-toxic, biodegradable, and environmentally friendly cellulose nanofiber / hydroxyapatite nanowire composite aqueous dispersion, which is dispersed with the assistance of cellulose nanofibers, which are biocompatible, heat-resistant, and flame-retardant. This method facilitates the application of hydroxyapatite nanowires in fields such as biomedicine, wearable devices, and environmentally friendly packaging materials.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterial preparation, and particularly relates to a new method for dispersing hydroxyapatite nanowires with the assistance of cellulose nanofibers. Background Art

[0002] Hydroxyapatite (HAP) is a naturally occurring mineral in the apatite family, composed of two components: hydroxyl groups and apatite. In vivo, hydroxyapatite is the primary inorganic component of human tooth enamel and human and animal bones. It is a biomineral formed through the gradual mineralization of an organic matrix under the control of genes and proteins. Once implanted in the body, hydroxyapatite exhibits high bioactivity, dissociating into calcium and phosphate ions that are absorbed by tissues, forming chemical bonds with them and promoting the repair of damaged tissues. Therefore, hydroxyapatite is an important material for tissue repair. Hydroxyapatite can be prepared by dry, wet, and hydrothermal methods. However, these synthetic hydroxyapatites are typically granular or rod-shaped, exhibiting poor flexibility. Researchers have used calcium oleate as a precursor and a solvothermal method to produce hydroxyapatite nanowires (HAPHWs) on a large scale, demonstrating high flexibility and addressing the inherent flexibility of hydroxyapatite. However, hydroxyapatite nanowires synthesized using the calcium oleate solvothermal method inevitably form an oleic acid bilayer on their surface, limiting their further processability. However, after removing the oleic acid bilayer using organic solvents such as ethanol, the hydroxyapatite nanowires cannot be evenly dispersed in aqueous solutions (the abundant carboxyl groups in the oleic acid bilayer give it a strong affinity for water molecules), thus limiting their practical applications. Therefore, finding a simple method for scalably dispersing hydroxyapatite nanowires in water is of great importance. Summary of the Invention

[0003] The purpose of the present invention is to address the deficiencies of the existing technology and provide a method and dispersion liquid for dispersing hydroxyapatite nanowires assisted by cellulose nanofibers, thereby obtaining a natural, non-toxic, easily degradable, and environmentally friendly cellulose nanofiber / hydroxyapatite nanowire composite aqueous dispersion liquid dispersed with the assistance of cellulose nanofibers with good biocompatibility, high temperature resistance, and flame retardancy in a simple and quick manner, which is beneficial to the application of hydroxyapatite nanowires in biomedicine, wearable devices, environmentally friendly packaging materials and other fields.

[0004] The present invention utilizes cellulose nanofibers, an abundant natural biomass resource, as a dispersant for hydroxyapatite nanowires, and achieves efficient dispersion of hydroxyapatite nanowires in an aqueous solution through a simple mixing and ultrasonic process.

[0005] Cellulose, the primary component of plant cell walls, is the most abundant renewable natural polymer on Earth. However, its insolubility in water and common organic solvents has hindered its practical applications. Cellulose nanofibers (CNFs) are cellulose fibrils with diameters of 1 to 100 nm and lengths of up to several microns, extracted from natural cellulose through a combination of physical, chemical, and biological methods. They possess excellent multifunctional properties, including adjustable surface chemistry, high mechanical properties, hydrophilicity, and biodegradability.

[0006] The method for dispersing hydroxyapatite nanowires with the aid of cellulose nanofibers provided by the present invention comprises the following steps:

[0007] (1) Wash the hydroxyapatite nanowires with anhydrous ethanol and deionized water respectively, add them into deionized water and stir them evenly, then perform ultrasonic dispersion. During the ultrasonic process, keep the liquid temperature at 4~25℃ or perform it in an ice bath to avoid the liquid from heating up, and obtain a hydroxyapatite nanowire dispersion;

[0008] (2) dispersing the cellulose nanofibers in deionized water to obtain a cellulose nanofiber dispersion;

[0009] (3) The hydroxyapatite nanowire dispersion and the cellulose nanofiber dispersion are stirred and mixed uniformly, and then ultrasonically dispersed. During the ultrasonic process, the liquid temperature is maintained at 4~25℃ or the process is carried out in an ice bath to obtain a uniform and stable cellulose nanofiber / hydroxyapatite nanowire dispersion.

[0010] In the above method, further, the cellulose nanofibers in step (2) are oxidized nanofibers mediated by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidation. The oxidation process introduces abundant surface negatively charged groups into the cellulose nanofibers, significantly improving the surface hydrophilicity and interaction ability of the cellulose nanofibers with water molecules, thereby achieving better hydrophilicity. Furthermore, the TEMPO-oxidized cellulose nanofibers have high strength, a large aspect ratio, and abundant surface functional groups. The present invention preferably uses CNF oxidized using this method.

[0011] In the above method, further, in step (3), the cellulose nanofibers and hydroxyapatite nanowires are in a mass ratio of (0.05-40):1; preferably, the solid content of the obtained cellulose nanofiber / hydroxyapatite nanowire dispersion is 0.05-2%.

[0012] In the above method, further, the cellulose nanofiber dispersion in step (2) is obtained by diluting a cellulose nanofiber aqueous dispersion having a mass concentration of 0.5% to 4% with deionized water, and magnetic stirring is performed at a speed of 400 to 1200 rpm / min during the dilution process.

[0013] In the above method, further, the mass concentration of the hydroxyapatite nanowire dispersion in step (1) is 0.05%~2%.

[0014] In the above method, further, in step (2), the mass concentration of the cellulose nanofiber dispersion is 0.05-2%.

[0015] In the above method, further, the stirring in step (1) is magnetic stirring, the stirring rate is 400~1200rpm / min, the magnetic stirring time is 5~20 min, the ultrasonic power is 600~1000W, and the ultrasonic dispersion time is 5~30 min.

[0016] In the above method, further, in step (2), the stirring is magnetic stirring, the stirring rate is 400~1200rpm / min, and the stirring time is 5~20 min.

[0017] In the above method, further, in step (3), the stirring is magnetic stirring, the stirring rate is 400~1200rpm / min, the magnetic stirring time is 5~20 min, the ultrasonic dispersion time is 10~40 min, and the ultrasonic power is 600~1000W.

[0018] In the above method, further, the ultrasonic dispersion is performed using a cell disruptor.

[0019] The present invention also provides a cellulose nanofiber / hydroxyapatite nanowire dispersion prepared by the above method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention utilizes the abundant surface functional groups of cellulose nanofibers to interact with hydroxyapatite nanowires through hydrogen bonds under ultrasound alone, achieving uniform dispersion in aqueous solution. This invention conveniently and rapidly produces a naturally non-toxic, biodegradable, and environmentally friendly cellulose nanofiber / hydroxyapatite nanowire composite aqueous dispersion, aided by the biocompatible, heat-resistant, and flame-retardant cellulose nanofibers. This facilitates the application of hydroxyapatite nanowires in biomedicine, wearable devices, and environmentally friendly packaging materials.

[0022] 2. The cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion of the present invention has an environmentally friendly and pollution-free preparation process, a simple process, and is easy to operate, and is suitable for industrialization.

[0023] 3. The cellulose nanofibers and hydroxyapatite nanowires of the present invention are widely available, inexpensive, non-toxic, and have excellent biocompatibility and biodegradability, making them environmentally friendly composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a physical digital photo of the cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion prepared in Example 1;

[0025] Figure 2 This is a scanning electron microscope photograph of the cellulose nanofiber / hydroxyapatite nanowire composite material prepared in Example 1 (obtained by drying the dispersion);

[0026] Figure 3 is the zeta potential diagram of the cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion prepared in Example 1;

[0027] Figure 4 These are actual digital photos of the cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion prepared in Example 1 before and after standing for one month;

[0028] Figure 5 This is a physical digital photo of the cellulose nanofiber / hydroxyapatite nanowire film prepared by vacuum filtration in Example 1. DETAILED DESCRIPTION

[0029] The following describes in detail a specific embodiment of a method for dispersing hydroxyapatite nanowires assisted by cellulose nanofibers according to the present invention with reference to the accompanying drawings.

[0030] In the following examples, TEMPO-oxidized cellulose nanofibers were used and purchased from the market.

[0031] Example 1

[0032] (1) Take 0.5 g of the prepared hydroxyapatite nanowires, add 99.5 g of deionized water to dilute it, stir it magnetically at a speed of 800 rpm / min for 10 min, and use a cell disruptor to perform ice bath ultrasonic dispersion treatment for 10 min to obtain a 0.5 wt% poorly dispersed hydroxyapatite nanowire aqueous dispersion.

[0033] (2) Weigh 50 g of 1 wt% cellulose nanofiber raw material (dispersion), add 50 g of deionized water to dilute it, and magnetically stir at 800 rpm / min for 10 min to obtain a 0.5 wt% cellulose nanofiber aqueous dispersion.

[0034] (3) Subsequently, 50 g of 0.5 wt% hydroxyapatite nanowire aqueous dispersion and 50 g of 0.5 wt% cellulose nanofiber aqueous dispersion were mixed in a mass ratio of 1:1, magnetically stirred at 800 rpm / min for 10 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 30 min to obtain a uniform and stable cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion with a solid content of 0.5 wt%.

[0035] With the assistance of cellulose nanofibers, hydroxyapatite nanowires are evenly dispersed in the aqueous solution, and the cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion appears milky white. Figure 1 The microstructure of the prepared cellulose nanofiber / hydroxyapatite nanowire composite material is shown in Figure 2 As shown in the figure, a large number of cellulose nanofibers can be seen wrapped around the surface of hydroxyapatite nanowires, helping them to be evenly dispersed. Figure 3 As shown in the figure, the zeta potential measured by the zeta potential analyzer is -40.1 mV, indicating good dispersibility. This is because a sufficient amount of cellulose nanofibers can interact with the surface of hydroxyapatite nanowires through hydrogen bonds according to the size effect under ultrasonic conditions, thereby uniformly dispersing them in the aqueous solution. Figure 4 As shown in the figure, the cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion showed no precipitation or aggregation after standing for one month, indicating excellent dispersion stability. The cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion was vacuum filtered to obtain a cellulose nanofiber / hydroxyapatite nanowire film of uniform thickness, as shown in the figure. Figure 5 As shown, it can be seen that the thickness and texture of the film are uniform.

[0036] Example 2

[0037] (1) Take 1 g of the prepared hydroxyapatite nanowires, add 99 g of deionized water to dilute it, stir it magnetically at a speed of 800 rpm / min for 10 min, and use a cell disruptor to perform ice bath ultrasonic dispersion treatment for 15 min to obtain a 1 wt% poorly dispersed hydroxyapatite nanowire aqueous dispersion.

[0038] (2) Weigh 50 g of 2 wt% cellulose nanofiber raw material, add 50 g of deionized water to dilute it, and magnetically stir at 800 rpm / min for 10 min to obtain a 1 wt% cellulose nanofiber aqueous dispersion.

[0039] (3) Then, 50 g of 1 wt% hydroxyapatite nanowire aqueous dispersion and 50 g of 1 wt% cellulose nanofiber aqueous dispersion were mixed in a ratio of 1:1, magnetically stirred at 800 rpm / min for 20 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 40 min to obtain a uniform and stable cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion with a solid content of 1 wt%.

[0040] Example 3

[0041] 0.5 g of the prepared hydroxyapatite nanowires was taken, diluted with 99.5 g of deionized water, magnetically stirred at a speed of 800 rpm / min for 15 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 10 min to obtain a 0.5 wt% aqueous dispersion of hydroxyapatite nanowires with poor dispersibility.

[0042] Weigh 50 g of 1 wt% cellulose nanofiber raw material, add 50 g of deionized water to dilute it, and magnetically stir it at 800 rpm / min for 15 min to obtain a 0.5 wt% cellulose nanofiber aqueous dispersion.

[0043] Subsequently, 25 g of 0.5 wt% hydroxyapatite nanowire aqueous dispersion and 50 g of 0.5 wt% cellulose nanofiber aqueous dispersion were mixed in a ratio of 1:2, magnetically stirred at 800 rpm / min for 15 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 20 min to obtain a uniform and stable cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion with a solid content of 0.5 wt%.

[0044] Example 4

[0045] 1 g of the prepared hydroxyapatite nanowires was taken, diluted with 99 g of deionized water, magnetically stirred at 800 rpm / min for 15 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 20 min to obtain a 1 wt% aqueous dispersion of hydroxyapatite nanowires with poor dispersibility.

[0046] Weigh 50 g of 2 wt% cellulose nanofiber raw material, add 50 g of deionized water to dilute it, and magnetically stir it at 800 rpm / min for 15 min to obtain a 1 wt% cellulose nanofiber aqueous dispersion.

[0047] Subsequently, 50 g of 1 wt% hydroxyapatite nanowire aqueous dispersion and 10 g of 1 wt% cellulose nanofiber aqueous dispersion were mixed in a ratio of 5:1, magnetically stirred at 800 rpm / min for 15 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 35 min to obtain a uniform and stable cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion with a solid content of 1 wt%.

[0048] Comparative Example

[0049] 0.5 g of the prepared hydroxyapatite nanowires was taken, diluted with 99.5 g of deionized water, magnetically stirred at 800 rpm / min for 10 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 10 min to obtain a 0.5 wt% aqueous dispersion of hydroxyapatite nanowires with poor dispersibility.

[0050] Weigh 50 g of 1 wt% cellulose nanofiber raw material, add 50 g of deionized water to dilute it, and magnetically stir it at 800 rpm / min for 10 min to obtain a 0.5 wt% cellulose nanofiber aqueous dispersion.

[0051] Subsequently, 50 g of 0.5 wt% hydroxyapatite nanowire aqueous dispersion and 2 g of 0.5 wt% cellulose nanofiber aqueous dispersion were mixed in a ratio of 25:1, magnetically stirred at 800 rpm / min for 10 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 30 min. The obtained cellulose nanofiber / hydroxyapatite nanowire aqueous dispersion with a solid content of 0.5 wt% had poor dispersibility. This was because the content of cellulose nanofibers was too small to completely cover the surface of the hydroxyapatite nanowires through hydrogen bonds, and thus exhibited poor dispersibility.

[0052] Comparative Example 2

[0053] 0.5 g of the prepared hydroxyapatite nanowires was taken, diluted with 99.5 g of deionized water, magnetically stirred at 800 rpm / min for 10 min, and ultrasonically dispersed in an ice bath using a cell disruptor for 10 min to obtain a 0.5 wt% aqueous dispersion of hydroxyapatite nanowires with poor dispersibility.

[0054] Weigh 50 g of 4 wt% cellulose nanofiber raw material, add 30 g of deionized water to dilute it, and magnetically stir it at a speed of 800 rpm / min for 10 min to obtain a cellulose nanofiber aqueous dispersion with a concentration greater than 2 wt%.

[0055] Subsequently, the hydroxyapatite nanowire aqueous dispersion and the cellulose nanofiber aqueous dispersion were mixed in a hydroxyapatite nanowire: cellulose nanofiber mass ratio of 1:1, magnetically stirred at a speed of 800 rpm / min for 10 min, and subjected to ice bath ultrasonic dispersion treatment using a cell disruptor for 30 min. The dispersion had poor dispersibility. This was because the CNF concentration was too high, making the mixture too viscous, resulting in the hydroxyapatite nanowires unable to fully contact the cellulose nanofibers and therefore unable to be evenly dispersed.

[0056] The above embodiments are merely illustrative of the technical solutions of the present invention. The method for dispersing hydroxyapatite nanowires with cellulose nanofibers as assisted by the present invention is not limited solely to the methods described in the above embodiments but is subject to the scope defined by the claims. Any modifications, supplements, or equivalent substitutions made by persons skilled in the art based on these embodiments are considered within the scope of the claims.

Claims

1. A method for dispersing hydroxyapatite nanowires assisted by cellulose nanofibers, characterized in that: The following steps are involved: (1) Wash the hydroxyapatite nanowires with anhydrous ethanol and deionized water respectively, add them into deionized water and stir them evenly, then perform ultrasonic dispersion. During the ultrasonic process, the liquid temperature is maintained at 4~25℃ or the process is performed in an ice bath to obtain a hydroxyapatite nanowire dispersion with a mass concentration of 0.05%~2%; (2) Dispersing cellulose nanofibers in deionized water to obtain a cellulose nanofiber dispersion with a mass concentration of 0.05-2%; (3) Stirring the hydroxyapatite nanowire dispersion and the cellulose nanofiber dispersion to uniformly mix, and then ultrasonically dispersing, maintaining the liquid temperature at 4-25°C or performing the dispersion in an ice bath during the ultrasonic process, to obtain a uniform and stable cellulose nanofiber / hydroxyapatite nanowire dispersion; wherein the cellulose nanofibers and the hydroxyapatite nanowires are mixed in a mass ratio of (0.05-40):1; the solid content of the obtained cellulose nanofiber / hydroxyapatite nanowire dispersion is 0.05-2%; The cellulose nanofibers in step (2) are oxidized nanofibers mediated by 2,2,6,6-tetramethylpiperidin-1-oxyl free radicals; The cellulose nanofiber dispersion in step (2) is obtained by diluting a cellulose nanofiber aqueous dispersion having a mass concentration of 0.5% to 4% with deionized water, and performing magnetic stirring at a speed of 400 to 1200 rpm / min during the dilution process.

2. The method according to claim 1, characterized in that The stirring in step (1) is magnetic stirring, the stirring rate is 400~1200 rpm / min, and the magnetic stirring time is 5~20 min; the ultrasonic power is 600~1000W, and the ultrasonic dispersion time is 5~30 min.

3. The method according to claim 1, characterized in that In step (2), the stirring is magnetic stirring, the stirring rate is 400~1200 rpm / min, and the stirring time is 5~20 min.

4. The method according to claim 1, characterized in that In step (3), the stirring is magnetic stirring, the stirring rate is 800 rpm / min, the magnetic stirring time is 5 to 20 min, the ultrasonic power is 600 to 1000 W, and the ultrasonic dispersion time is 10 to 40 min.

5. A cellulose nanofiber / hydroxyapatite nanowire dispersion prepared by the method according to any one of claims 1 to 4.

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