基于金属卟啉偶联聚合物的葡萄糖传感器及血糖监测研究

糖尿病是一种由胰岛素分泌和作用异常所引起的血糖代谢紊乱疾病，严重威胁着全球四亿多人口的生命健康。精准的血糖检测是糖尿病诊断及预后管理重要的一环。目前常见的血糖检测方法包括：间隔性指尖采血的检测方法和植入式连续性血糖监测方法。其中，连续性血糖监测能够实时提供血糖数据，是目前最具应用前景的糖尿病管理手段。商用的连续性血糖监测方法大多基于电化学传感方法而开发，在组织损伤、信号漂移等方面仍面临着较大的挑战。近年来，基于光学的连续性血糖检测方法引起了研究者的广泛关注。高亮度且生物相容性优良的磷光纳米材料表现出巨大的应用潜力，基于该种材料开发的新型光学血糖传感器为解决上述问题提供了方案。然而基于磷光纳米材料的葡萄糖传感器仍存在着稳定性差、准确性低等问题。

本论文利用金属卟啉偶联聚合物制备纳米探针，进一步偶联葡萄糖氧化酶研发了具有内参比特性的葡萄糖传感器。该传感器包括氧敏感的钯卟啉偶联聚合物和共价连接聚合物的罗丹明两部分，能够实时监测活体血糖浓度的动态变化。实验结果表明，传感器的双通道（620 nm，670 nm）发光强度比值与血糖浓度变化有着密切相关性，适应于构建比率型光学传感器。为了进一步提高体内血糖监测系统的长期稳定性，本研究将过氧化氢酶偶联至葡萄糖传感器的表面来产生酶级联系统，消耗血糖监测过程中所产生的毒副产物过氧化氢，降低其细胞毒性。细胞水平的结果显示，过氧化氢酶可以大幅提高传感材料的生物相容性，提高孵育细胞的存活率。14天的长期活体实验结果显示偶联过氧化氢酶的传感器的长期稳定性优于单酶传感器，与单酶传感器相比，灵敏度提升了1.3倍。综上，本研究制备了具有内参比特性的植入式光学连续性血糖传感器，能够实现活体的实时血糖检测；通过偶联过氧化氢酶进一步构建酶级联系统，延长了血糖实时监测的时效，为提升血糖传感的器长期稳定性的提供了有益参考。

Diabetes, characterized by abnormal insulin secretion and function, poses a threat to the health of 400 million people around the world. Accurate detection of blood glucose levels is a significant step of the diagnosis and management of diabetes. Currently, the common methods for blood glucose management mainly include intermittent fingerstick testing and invasive continuous glucose monitoring (CGM). CGM offers real-time blood glucose data and has emerged as a highly promising modality for diabetes management. While commercial continuous glucose monitoring devices predominantly rely on electrochemical sensing methods, they encounter challenges such as tissue damage and signal drift. Optical-based continuous glucose monitoring has garnered significant attention from researchers in recent years. Phosphorescent nanomaterials with the advantages of small size distribution and high biocompatibility, hold immense potential for the development of novel long-term optical blood glucose sensors. However, there are still many issues to be resolved, such as stability and accuracy that require further refinement.

Here, an optical glucose sensor with internal reference characteristics was designed and prepared by incorporating glucose oxidase (GOx) on the surface of luminescent nano-probe, which was covalent incorporation of metalloporphyrin. The sensor mainly consists of oxygen-sensitive palladium porphyrin-conjugated polymers and rhodamine which were covalently linked with polymer, and it can monitor real-time changes in blood glucose levels in vivo. Experimental results indicate that the ratio of the dual-channel (670 nm, 620 nm) luminescence intensity of the sensor is closely related to changes in blood glucose concentration, rendering it suitable for constructing a ratio-type optical sensor.

Furthermore, to enhance the long-term stability of the glucose monitoring system in vivo, catalase (CAT) was conjugated to the sensor surface, creating an enzymatic cascade system that effectively decomposed the toxic by-product hydrogen peroxide (H₂O₂) generated during glucose monitoring, thereby reducing cytotoxicity. The results of in vitro experiments demonstrated that catalase significantly improved the biocompatibility of the sensing material and increased cell viability. Subsequently, the results of long-term experiment in vivo conducted over 14 days indicated that the catalase-coupled NP-GOx-CAT exhibited superior photostability compared to the single enzyme sensor NP-GOx, improving the sensitivity up to 230%. In conclusion, this study developed an implantable optical glucose sensor with internal reference characteristics, which can achieve real-time glucose monitoring in vivo. The enzyme cascade system was further constructed by conjugating with catalase, which significantly prolonged the time of real-time blood glucose monitoring, and offered valuable insights for enhancing the long-term stability of blood glucose sensing.

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