Francis Shinto Mundackal, Sanabria Hugo, Podila Ramakrishna
Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA.
Biosensors (Basel). 2025 Apr 24;15(5):269. doi: 10.3390/bios15050269.
Colloidal quantum dots (QDs) and graphene hybrids have emerged as promising platforms for optoelectronic and biosensing applications due to their unique photophysical and electronic properties. This study investigates the fundamental mechanism underlying the photoluminescence (PL) quenching and recovery in graphene-QD hybrid systems using single-layer graphene field-effect transistors (SLG-FETs) and time-resolved photoluminescence (TRPL) spectroscopy. We demonstrate that PL quenching and its recovery are primarily driven by charge transfer, as evidenced by an unchanged fluorescence lifetime upon quenching. Density functional theory calculations reveal a significant charge redistribution at the graphene-QD interface, corroborating experimental observations. We also provide a simple analytical quantum mechanical model to differentiate charge transfer-induced PL quenching from resonance energy transfer. Furthermore, we leverage the charge transfer mechanism for ultrasensitive biosensing to detect biomarkers such as immunoglobulin G (IgG) at femtomolar concentrations. The sensor's electrical response, characterized by systematic shifts in the Dirac point of SLG-FETs, confirms the role of analyte-induced charge modulation in PL recovery. Our findings provide a fundamental framework for designing next-generation graphene-based biosensors with exceptional sensitivity and specificity.
胶体量子点（QDs）与石墨烯的杂化物因其独特的光物理和电子特性，已成为光电子和生物传感应用中颇具前景的平台。本研究利用单层石墨烯场效应晶体管（SLG-FETs）和时间分辨光致发光（TRPL）光谱，探究了石墨烯-QD杂化体系中光致发光（PL）猝灭和恢复的基本机制。我们证明，PL猝灭及其恢复主要由电荷转移驱动，猝灭时荧光寿命不变即为明证。密度泛函理论计算揭示了石墨烯-QD界面处显著的电荷重新分布，证实了实验观察结果。我们还提供了一个简单的解析量子力学模型，以区分电荷转移诱导的PL猝灭和共振能量转移。此外，我们利用电荷转移机制进行超灵敏生物传感，以检测飞摩尔浓度的生物标志物，如免疫球蛋白G（IgG）。该传感器的电响应以SLG-FETs狄拉克点的系统性偏移为特征，证实了分析物诱导的电荷调制在PL恢复中的作用。我们的研究结果为设计具有卓越灵敏度和特异性的下一代基于石墨烯的生物传感器提供了一个基本框架。
