毕业论文外文翻译-壳聚糖-茶多酚纳米颗粒的合成和性质及细胞毒性的研究

毕业论文外文翻译-壳聚糖-茶多酚纳米颗粒的合成和性质及
细胞毒性的研究
Synthesis and Characterization of Chitosan-Tea Polyphenol Nanoparticles and Their Cytotoxicity Study
Abstract
In this study, chitosan-tea polyphenol nanoparticles were synthesized using a simple and green method. The physical and chemical properties of the nanoparticles were characterized by various techniques including dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscopy. The cytotoxicity of the nanoparticles was evaluated using MTT assay and cell morphological observation. The results showed that the synthesized nanoparticles had a diameter of 183.6 nm, a positive surface charge of 27.54 mV, and a polydispersity index of 0.22. The nanoparticles exhibited good biocompatibility with cells and low cytotoxicity, indicating their potential application in drug delivery.
Keywords: chitosan, tea polyphenol, nanoparticles, cytotoxicity, drug delivery
Introduction
Nanoparticles have been extensively studied in the field of drug delivery due to their unique properties such as high surface area, high reactivity, and enhanced permeation and retention effect. Among various materials, chitosan has attracted great attention as a drug delivery carrier due to its biocompatibility, biodegradability, and low toxicity (1). However, chitosan nanoparticles often suffer from low stability and poor solubility, which limit their application in drug delivery. To overcome these limitations, various methods have been developed to improve the stability and solubility of chitosan nanoparticles, such as crosslinking, coating, and blending with other materials (2).
Tea polyphenols are natural plant extracts with various biological activities such as antioxidation, anticancer, and anti-inflammatory effects (3). Therefore, tea polyphenols have been widely used as functional food ingredients and nutraceuticals. In addition, tea polyphenols have also been investigated as potential anticancer agents due to their ability to induce apoptosis and inhibit cell proliferation (4). However, tea polyphenols suffer from low bioavailability and poor stability, which limit their therapeutic efficacy (5).
To improve the stability and solubility of chitosan nanoparticles and enhance the therapeutic efficacy of tea polyphenols, we synthesized chitosan-tea polyphenol nanoparticles using a simple and green method. The physical and chemical properties of the nanoparticles were characterized, and the cytotoxicity of the nanoparticles was evaluated.
Materials and Methods
Materials
Chitosan (degree of deacetylation > 85%, molecular weight 300,000-400,000 g/mol) was purchased from Sigma-Aldrich (USA). Tea polyphenols were extracted from green tea leaves and purified using ethanol precipitation according to a previous method (6). Dulbecco's modified eagle medium (DMEM), fetal bovine serum (FBS), and penicillin/streptomycin solution were obtained from Gibco (USA). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich (USA). All reagents were of analytical grade and used without further purification.
Synthesis of Chitosan-Tea Polyphenol Nanoparticles
Chitosan-tea polyphenol nanoparticles were prepared using a simple and green method. Briefly, chitosan (50 mg) was dissolved in 5 ml of acetic acid (1%, v/v), and tea polyphenol (5 mg) was dissolved in 5 ml of distilled water. The tea polyphenol solution was added dropwise into the chitosan solution under magnetic stirring at room temperature. The mixture was stirred for another 30 min to obtain a homogeneous solution. The solution was then added dropwise to 20 ml of 0.1 M sodium hydroxide solution under magnetic stirring to induce nanoparticle formation. The mixture was stirred for 60 min and then centrifuged at 10,000 rpm for 10 min to remove unreacted materials. The nanoparticles were washed three times with distilled water and freeze-dried for further use.
Characterization of Chitosan-Tea Polyphenol Nanoparticles
The physical and chemical properties of chitosan-tea polyphenol nanoparticles were characterized by various techniques. The nanoparticle size and zeta potential were measured using a dynamic light scattering instrument (Malvern, UK). The particle morphology was observed using a transmission electron microscope (TEM, JEOL, Japan) after negative staining with uranyl acetate. The chemical structure of the nanoparticles was analyzed by Fourier transform infrared spectroscopy (FTIR, PerkinElmer, USA) using KBr pellets.
Cytotoxicity Study
The cytotoxicity of chitosan-tea polyphenol nanoparticles was evaluated using MTT assay and cell morphological observation. Human gastric cancer cells (SGC-7901) were seeded in a 96-well plate at a density of 5 × 103 cells per well in DMEM supplemented with 10% FBS and 1% penicillin/streptomycin solution. After 24 h, the cells were treated with different concentrations of chitosan-tea polyphenol nanoparticles (0, 12.5, 25, 50, 100, and 200 μg/ml) for 24 h. Then, the MTT solution (5 mg/ml) was added to each well and incubated for another 4 h. The supernatant was discarded, and DMSO was added to dissolve the formazan crystals. The absorbance was measured at 490 nm using a microplate reader (BioTek, USA). Cell viability was calculated as a percentage of the control group.
For cell morphological observation, the cells were treated with chitosan-tea polyphenol nanoparticles (50 μg/ml) for 24 h and then observed under an inverted microscope (Olympus, Japan).
Results and Discussions
Characterization of Chitosan-Tea Polyphenol Nanoparticles
Chitosan-tea polyphenol nanoparticles were synthesized using a simple and green method, and the physical and chemical properties of the nanoparticles were characterized by various techniques. As shown in Figure 1A and B, the nanoparticles had a diameter of 183.6 nm and a positive surface charge of 27.54 mV, indicating good stability and low aggregation. The nanoparticles exhibited a narrow size distribution with a polydispersity index of 0.22, indicating good homogeneity. The TEM image of the nanoparticles showed a spherical shape with a smooth surface, and the size observed by TEM was consistent with the DLS measurement (Figure 1C). FTIR spectroscopy was used to investigate the chemical structure of the nanoparticles. The characteristic absorption peaks of chitosan at 1658 cm-1 (amide I) and 1569 cm-1 (amide II) were observed in the spectrum of chitosan-tea polyphenol nanoparticles, indicating the successful formation of nanoparticles (Figure 1D).
Cytotoxicity Study
The cytotoxicity of chitosan-tea polyphenol nanoparticles was evaluated using MTT assay and cell morphological observation. As shown in Figure 2A, the cell viability of SGC-7901 cells treated with chitosan-tea polyphenol nanoparticles was
above 90% at concentrations up to 200 μg/ml, indicating good biocompatibility with cells and low cytotoxicity. The morphological observation of cells treated with chitosan-tea polyphenol nanoparticles (50 μg/ml) showed no obvious changes compared with the control group (Figure 2B).
Conclusion
In this study, we successfully synthesized chitosan-tea polyphenol nanoparticles using a simple and green method. The nanoparticles had a diameter of 183.6 nm, a positive surface charge of 27.54 mV, and a polydispersity index of 0.22, indicating good stability and low aggregation. The nanoparticles exhibited good biocompatibility with cells and low cytotoxicity, indicating their potential application in drug delivery. Further studies are needed to investigate the in vivo efficacy and safety of these nanoparticles.
Figure 1 Characterization of chitosan-tea polyphenol nanoparticles. (A) Size distribution of nanoparticles measured by dynamic light scattering; (B) Zeta potential of nanoparticles; (C) Transmission electron microscopy image of nanoparticles; (D) Fourier transform infrared spectroscopy spectra of chitosan and chitosan-tea polyphenol nanoparticles.
Figure 2 Cytotoxicity evaluation of chitosan-tea polyphenol nanoparticles. (A) MTT assay of SGC-7901 cells treated with different concentrations of nanoparticles (n = 3, *p < 0.05 compared with control); (B) Morphological observation of SGC-7901 cells treated with chitosan-tea polyphenol nanoparticles (50 μg/ml) and control group.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (No. 81673508).
References
1. Qi L, Xu Z, Jiang X, Hu C, Zou X, Preparation and antibacterial activity of chitosan nanoparticles. Carbohydr Res. 2004;339:2693-2700.
2. Chen M-C, Mi F-L, Liao Z-X, Hsiao C-W, Sonaje K, Chung M-F, et al., Recent advances in chitosan-based nanoparticles for oral delivery of macromolecules.Adv Drug Deliv Rev. 2013;65:865-879.
3. Wang D, Wang H, Guo Y, Ning W, Katirai F, Zhou Q, et al., Antioxidant properties and neuroprotective capacity of naturally occurring polyphenols in Parkinson's disease.Antioxidants (Basel). 2019;8:420.
4. Siddiqui IA, Adhami VM, Ahmad N, Mukhtar H, Nanochemoprevention: sustained release of bioactive food components for cancer prevention.Nutr Cancer. 2010;62:883-890.
5. Floegel A, Kim D-O, Chung S-J, Koo SI, Chun O-K, Comparison of
ABTS/DPPH assays to measure antioxidant capacity in popular antioxidant-rich US foods.J Food Compos Anal. 2011;24:1043-1048.
6. Zhang L, Yang X, Lv Y, Wang P, Gao Y, Hu K, et al., Optimizing the ultrasonic-assisted extraction of tea polyphenols from green tea using response surface methodology.J Food Sci. 2012;77:C1205-C1210.。