植入式葡萄糖感測器之設計製作與動物實驗探討

Design, implementation and in vivo studies of an implantable glucose biosensor

楊泱澧(Yang-Li Yang)

指導教授 ： 婁世亮

中原大學/工學院/生物醫學工程研究所/博士(2011年)

https://doi.org/10.6840/CYCU.2011.00034

摘要

本論文之目的為開發ㄧ植入式無線葡萄糖感測系統，並植入於老鼠體內探討其功能性。本系統包含外部控制系統之人機介面及植入式電化學葡萄糖感測器，藉由無線射頻技術使得控制系統與植入端達到雙向傳輸之目的。外部系統以無線射頻耦合方式提供內部植入端所需的電能，藉射頻載波編碼方式命令植入端進行電化學感測，並將感測得之訊號傳送至外部顯示。植入端系統之微小化及封裝是為了便於將之植入老鼠體內，除了自製的微小化電極外，以聚二甲基矽氧烷封裝植入端系統，此微小化電極組乃是將工作電極、參考電極及輔助電極沉積於一矽晶上。本研究另一主軸為降低蛋白質吸附於工作電極，在此是以熱塑性聚氨酯(thermoplastic polyurethane, TPU)當作外層薄膜，將葡萄糖氧化酶(glucose oxidase, GOx)固定於TPU與微小電極之間，並於模擬組織間質液之環境中(組織間質替代液)以AUTOLAB PGSTAT 10測量葡萄糖濃度，藉此評估蛋白質吸附之程度，評估結果顯示，濃度為30 mg/ml之TPU具有降低蛋白質吸附之特性，以該TPU濃度製作之電極於模擬環境中測量亦有21天的穩定性，值得重視的是，該電極中之酵素活行仍維持在100%左右。此外，植入式感測系統之特性探討亦相當重要，本研究以所開發之系統與AUTOLAB進行探討，以相同之感測電極分別偵測不同濃度之過氧化氫，藉此評估植入式感測系統之解析度，由結果顯示，本系統及AUTOLAB之解析度分別為114及< 9.7 nA，有鑑於此，TPU薄膜應用於植入式葡萄糖感測系統之最佳濃度需得進一步評估，這項評估的結果顯示，以20 mg/ml TPU為固定酵素之薄膜，於組織間質替代液中檢測不同濃度之葡萄糖，本研究完成的系統其所擷取之電流訊號具有可分辨性。吾人乃將此感測器埋植於正常與糖尿病老鼠之體內進行實驗，當靜脈血糖濃度產生變化時，系統亦能測量出組織間質液之葡萄糖濃度有顯著差異，靜脈血糖濃度變化之時間點與本系統在組織間質液所偵測得葡萄糖濃度變化之對應時間點有30至170分鐘的遲滯。

關鍵字

植入式葡萄糖感測器 ； 無線射頻技術 ； 糖尿病 ； 熱塑性聚氨酯 ； 葡萄糖氧化酶

並列摘要

This thesis developed an implantable wireless glucose sensing system and studied its functionality in rats. The system includes an external controller for serving as a human-system interaction interface and an implant unit for electrochemically sensing glucose. The communications between the controller and the implant are through a pair of antenna (or coils) based on peer-to-peer radio frequency (RF) technology. The electric power of the implant is supplied by the controller by means of RF coupling. The commands issued from the controller to the implant and the glucose signals sent back from the electrochemical analyzer of the implant to the controller all rely on the wireless RF technology. To be able to utilize the implant in rats, the implant unit requires not only miniaturization but also hermetically packaging. The whole part of the implant unit was sealed with poly-dimethylsiloxane except for a mini-electrode set. It is self-developed and is a piece of silicon containing working, reference and counter electrodes. This work also focuses on reducing protein absorption on surface of the electrode set when it is implanted within the rats. The working electrode modified with various TPU concentrations for GOx immobilization was used to evaluate the impact of the protein absorption. The evaluation study was carried out in simulated interstitial fluid (interstitial fluid surrogate, ISF surrogate) by an AUTOLAB PGSTAT10. Results indicate that 30 mg/ml of TPU reduced protein absorption most effectively. The modified electrode exhibited excellent stability as well because the TPU retained approximately 100% of GOx activity for more than 21 days. How the performance of the entire implantable glucose sensing system is even important in this work. Hydrogen peroxide signal measurements by the developed system and AUTOLAB were performed to evaluate the signal detection resolution. Results indicate the resolutions of the developed system and AUTOLAB were 114 and < 9.7 nA, respectively. This implied the TPU membrane to be used with the developed glucose sensing system requires modifications. The experimental results indicate that the developed system can detect a distinguishable glucose current response from ISF surrogate by using a 20 mg/ml TPU membrane. This implantable glucose biosensor with a TPU membrane was subsequently implanted in normal and diabetic rats. The signal responses obtained from the study rats’ ISF exhibited a significant difference when the blood glucose level changed. A comparison of intravenous and ISF glucose levels revealed a 30 to 170 minutes delay.

並列關鍵字

radio frequency technology ； thermoplastic polyurethane (TPU) ； glucose oxidase (GOx) ； implantable glucose biosensor ； diabetes mellitus

參考文獻

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