在資源有限的地區，使用方便、一次性的定點照護檢測(POCT)能有助於及早篩檢及避免嚴重疾病發生。而藉由進一步的定量分析可以進行更準確的診斷，而非僅單純的陰性、陽性二分法。本研究開發一種能藉由簡易比色法的診斷裝置，以達到快速檢測檢體中的生物標誌物(biomarker)的目的，此裝置包含免疫微珠(immunocomplexed microbeads, dp = 40 µm)、表面修飾含有抗體的金奈米粒子AuNP和含有45 μm孔徑之多孔性水凝膠(porous hydrogel)之毛細管(capillary tube)。在所提出的方法中，當目標生物標記物存在時，具功能性的金奈米粒子會附著在直徑較大的免疫微珠上，形成”金奈米粒子-生物標誌物-免疫微珠”型態之三明治結構免疫複合物。之後將其注入多孔性水凝膠的玻璃毛細管中，使其通過多孔性水凝膠，再由玻璃毛細管頂端的海綿吸收液體提供驅動的流力，幫助後續檢體完全流過多孔水凝膠進行尺寸篩選。當帶有金奈米粒子的免疫複合物聚集形成較大的體積時，會因而阻塞而留於多孔水凝膠入口端處。此時該處將會隨生物標誌物濃度上升而有逐漸加深的紅色產生。量化部份，我們使用智慧手機拍攝裝置對應不同濃度的目標生物標記物造成的顏色的變化，並使用影像分析軟體進行精確的定量分析。最終研究結果顯示，本技術僅需1 µL的檢體，檢測極限（LOD）即能達到200 ng / mL且與使用常規分光光度計獲得的濃度測量值相比，準確性已可達79%。此外，我們也透過從比較臨床眼淚檢體中因糖尿病性視網膜病變所產生的生物標記物脂蛋白Lipocalin-1(LCN-1)濃度變化來做評估。結果中發現所有健康受試者眼淚檢體中的LCN-1水平皆低於其他糖尿病受試者（PDR或NPDR患者），證明了該設備的實用性與驗證本技術在臨床應用中的潛力。總體而言，本研究開發之毛細管診斷裝置可實現居家照護，並為資源有限的地區提供低成本、簡單且可靠的早期診斷工具。

Handy and disposable point-of-care diagnostics facilitate early screening of severe diseases in resource-limited areas. To support the urgent needs demanded in the inconvenient sites, a simple colorimetric diagnostic device consisting of a capillary tube, immunocomplexed particles, and a porous hydrogel was developed herein to realize rapid detection of biomarkers in bioanalytes. In the proposed approach, functionalized gold nanoparticles would attach to large capture particles (dp=40 µm) to form sandwiched immunocomplexes in the presence of target biomarkers. A porous hydrogel with a pore size of 45 µm was filled inside a glass capillary for size sieving. A dark red color would progressively emerge when the sandwiched immunocomplexed particles were blocked by the porous hydrogel because of the aggregated gold nanoparticles. The visible colorimetric aggregation was also recorded using a smartphone and analyzed with imaging software. The limit of detection of the technique eventually reached 200 ng/mL. Only 1 µL of sample fluid was required for the detection. It was shown that the proposed detection could reach 79% accuracy compare to those obtained using conventional spectrophotometry technique. The practicability of the proposed device was demonstrated by measuring a diabetic retinopathy biomarker, Lipocalin-1 (LCN-1), from human tear. All healthy subjects showed lower intensity levels than the other diabetic counterparts (PDR or NPDR patients), implying the potential of the technique used in clinical applications. Overall, the diagnostic platform presented in this study promotes the point-of-care-testing and provides a low-cost, compact, and reliable tool for early diagnosis in resource-limited areas.

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