Hou Xuemei, Zhao Huijing, Zhang Ke-Qin, Meng Kai
College of Textile and Clothing Engineering, Soochow University, No. 178 Ganjiang Road, Suzhou 215006, China.
National Engineering Laboratory for Modern Silk (Suzhou), No. 199 Ren'ai Road, Industrial Park, Suzhou 215123, China.
Materials (Basel). 2022 Dec 9;15(24):8787. doi: 10.3390/ma15248787.
In recent years, there has been an increase in demand for pH color-changing materials. These materials can visually communicate signals to people by connecting pH changes with color information. Embedding pH indicators into fibers to create flexible color-changing materials is an effective way to develop daily wearable products. For the stability of the indicator and the indirect contact of the indicator with the human body, it is usually necessary to encapsulate it in capsules. In this study, different pH indicators (Thymol Blue-TB, Bromocresol Green-BCG, and Bromocresol Purple-BCP) were mixed into a wide-domain pH color-changing indicator and encapsulated with ethyl cellulose (EC) by the flash nanoprecipitation (FNP) method using a new-type droplet-shaped confined impinging jet mixer. The effects of flow rate, core-to-wall ratio, and mixed solution concentration on the formation of the nanocapsules were investigated. In addition, the morphology, particle size, size distribution, dispersion stability, and encapsulation efficiency were systematically studied. At a core-to-wall ratio of 1:2, a mixed solution with a concentration of 6 mg/mL and a feed flow rate of 40 mL/min produced nanocapsules with an average particle size of 141.83 ± 0.98 nm and a PDI of 0.125 ± 0.01. Furthermore, a zeta potential with a range of -31.83 ± 0.23 mV and an encapsulation efficiency of 75.20 ± 1.72% were observed at 1:2 core-to-wall ratios. It was concluded that the color of the nanocapsules continuously changed from yellow to green and green to blue when the pH range was increased from 3 to 10. The color-changing nanocapsules were then embedded into sodium alginate hydrogel fibers, resulting in the same color-changing trend (pH 3-10) as that obtained for the nanocapsules. This study can be useful for the pH monitoring of various body fluids, such as wound exudate, urine, and sweat.
近年来，对pH变色材料的需求不断增加。这些材料可以通过将pH变化与颜色信息联系起来，以视觉方式向人们传达信号。将pH指示剂嵌入纤维中以制造柔性变色材料是开发日常可穿戴产品的有效方法。为了保证指示剂的稳定性以及使其与人体间接接触，通常需要将其封装在胶囊中。在本研究中，将不同的pH指示剂（百里酚蓝 - TB、溴甲酚绿 - BCG和溴甲酚紫 - BCP）混合制成宽域pH变色指示剂，并使用新型液滴形受限撞击射流混合器通过闪式纳米沉淀（FNP）法用乙基纤维素（EC）进行封装。研究了流速、核壳比和混合溶液浓度对纳米胶囊形成的影响。此外，还系统研究了其形态、粒径、粒径分布、分散稳定性和包封率。在核壳比为1:2、浓度为6 mg/mL的混合溶液和进料流速为40 mL/min的条件下，制备出平均粒径为141.83 ± 0.98 nm、多分散指数（PDI）为0.125 ± 0.01的纳米胶囊。此外，在核壳比为1:2时，观察到zeta电位范围为 - 31.83 ± 0.23 mV，包封率为75.20 ± 1.72%。得出的结论是，当pH范围从3增加到10时，纳米胶囊的颜色从黄色连续变为绿色，再从绿色变为蓝色。然后将变色纳米胶囊嵌入海藻酸钠水凝胶纤维中，得到与纳米胶囊相同的变色趋势（pH 3 - 10）。该研究可用于各种体液（如伤口渗出液、尿液和汗液）的pH监测。
