早期偵測如 HE4 等癌症生物標誌物對於提升卵巢癌的治療成效至關重要。然而，傳統診斷工具在檢測低濃度標誌物時，往往缺乏足夠的靈敏度。側向流分析 (LFA) 具備免儀器、快速且易於操作的優勢，適合應用於現場檢測 (POC)，但在早期癌症診斷中，其靈敏度仍是一大限制。
本研究探討金奈米粒子 (AuNPs) 尺寸對針對 HE4 標誌物之 LFA 靈敏度的影響。實驗中合成了四種尺寸 (25、39、69 與 88 nm) 的 AuNPs，並進行膠體穩定性表徵，利用 MUA 作為連結基進行表面修飾，透過 EDC/NHS 化學反應將單株抗 HE4 抗體共價鍵結於 AuNPs 表面。接著將修飾後的 AuNP 引入夾心式 LFA 中，使 HE4 分子被 AuNPs 標記的抗體與檢測線上的次級抗體夾擊捕捉。結果顯示，在所測試的尺寸中，69 nm AuNPs 兼具最佳訊號強度與流動速率平衡，檢測極限 (LOD) 達到 0.1 ng/mL，優於多數先前報導的 AuNP-LFA 系統。較小粒徑的 AuNPs 具有較佳的流動性，而較大粒徑則提供較強的光學訊號，凸顯了尺寸依賴的性能取捨關係。
本研究結果顯示，奈米粒子尺寸與表面功能化對 LFA 靈敏度具有關鍵影響。其中，69 nm AuNPs 在流體動力學與訊號增強間達到最佳平衡，能高靈敏檢測臨床相關濃度的 HE4。此研究證明，透過策略性優化奈米材料特性，可顯著提升檢測效能。本系統兼具低成本與高效能，適用於早期卵巢癌檢測，並適合在資源有限的現場檢測應用。

Early detection of cancer biomarkers, such as human epididymis protein 4 (HE4), is crucial for improving outcomes in ovarian cancer. However, conventional diagnostic tools often lack the sensitivity needed to detect low biomarker concentrations. Lateral flow assays (LFAs) provide an affordable, rapid, and user-friendly platform suitable for point-of-care (POC) applications, but their limited sensitivity remains a major challenge in early-stage cancer diagnostics.
This study evaluates the impact of gold nanoparticle (AuNP) size on the sensitivity of LFAs for HE4 detection. Four AuNP sizes (25, 39, 69, and 88 nm) were synthesized, characterized for colloidal stability, and functionalized with 11-mercaptoundecanoic acid (MUA) linkers. Monoclonal anti-HE4 antibodies were covalently conjugated to the AuNPs using EDC/NHS chemistry. The functionalized AuNPs were integrated into a sandwich-format LFA, in which HE4 was captured between AuNP-labeled antibodies and secondary antibodies immobilized on the test line. Among the tested sizes, 69 nm AuNPs achieved the optimal balance between signal intensity and flow rate, reaching a limit of detection (LOD) of 0.1 ng/mL—superior to several previously reported AuNP-based LFA systems. While smaller AuNPs exhibited enhanced mobility, larger particles generated stronger optical signals, revealing a size-dependent trade-off in assay performance.
These results underscore the critical influence of nanoparticle size and surface functionalization on LFA sensitivity. Specifically, 69 nm AuNPs provided the best compromise between flow dynamics and signal enhancement, enabling highly sensitive HE4 detection at clinically relevant levels. This work demonstrates that rational optimization of nanomaterial properties can substantially improve LFA performance, offering a cost-effective and portable solution for early ovarian cancer detection, particularly in resource-limited settings.

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