Nurjis Farwa, Ali Rafaqat, Ali Hina
National Institute of Lasers and Optronics College, Pakistan Institute of Engineering and Applied Sciences Nilore 45650 Islamabad Pakistan
RSC Adv. 2025 Aug 28;15(37):30711-30726. doi: 10.1039/d5ra04569j. eCollection 2025 Aug 22.
Quantum dots (QDs) have diverse applications, ranging from optics and energy to biomedical. In this study, carbon quantum dots (CQDs) were synthesized using glucose and tryptophan as precursors using one-step microwave (MW) and sand bath (SB) thermal methods, and the CQDs exhibit distinct photoluminescence behaviors. CQD-SB shows enhanced and stable fluorescence despite its amorphous structure, likely due to prolonged thermal treatment, facilitating the formation of robust surface states and stable reaction products. Notably, CQD-SB generates a dual emissive bands activated at both shorter and longer excitation wavelengths (330-390 nm) reveals both core-localized and surface bound group emission. This stable dual emission suggests a hybrid fluorescence mechanism involving excitation, concentration and size-dependent effects. However, CQD-MW possesses a partially crystalline structure and exhibits excitation-dependent dual emission even at higher excitation energies, showing less stability. This behavior of CQD-MW is due to rapid carbonization and limited passivation owing to instant microwave heating. Fluorescence staining reveals that CQD-SB offers stronger and more stable blue and green emission in human buccal and onion epidermal cells, supporting its potential as an efficient bioimaging probe and alternative to synthetic dyes.
量子点（QDs）有多种应用，涵盖从光学、能源到生物医学等领域。在本研究中，以葡萄糖和色氨酸为前驱体，采用一步微波（MW）和沙浴（SB）热法合成了碳量子点（CQDs），且CQDs表现出独特的光致发光行为。尽管CQD-SB具有非晶结构，但其荧光增强且稳定，这可能归因于延长的热处理过程，有利于形成稳健的表面态和稳定的反应产物。值得注意的是，CQD-SB在较短和较长激发波长（330 - 390 nm）下均能产生双发射带，揭示了核心局域发射和表面结合基团发射。这种稳定的双发射表明存在一种涉及激发、浓度和尺寸依赖效应的混合荧光机制。然而，CQD-MW具有部分晶体结构，即使在较高激发能量下也表现出激发依赖的双发射，稳定性较差。CQD-MW的这种行为是由于微波瞬间加热导致快速碳化和有限的钝化作用。荧光染色显示，CQD-SB在人颊细胞和洋葱表皮细胞中能提供更强且更稳定的蓝色和绿色发射，支持其作为高效生物成像探针以及合成染料替代品的潜力。
