Szapoczka Wiktoria Karolina, Olla Chiara, Carucci Cristina, Truskewycz Adam Leo, Skodvin Tore, Salis Andrea, Carbonaro Carlo Maria, Holst Bodil, Thomas Peter James
Department of Physics and Technology, University of Bergen, 5007 Bergen, Norway.
Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Italy.
Nanomaterials (Basel). 2024 Sep 2;14(17):1434. doi: 10.3390/nano14171434.
Ocean acidification has become a major climate change concern requiring continuous observation. Additionally, in the industry, pH surveillance is of great importance. Consequently, there is a pressing demand to develop robust and inexpensive pH sensors. Ratiometric fluorescence pH sensing stands out as a promising concept. The application of carbon dots in fluorescent sensing presents a compelling avenue for the advancement of pH-sensing solutions. This potential is underpinned by the affordability of carbon dots, their straightforward manufacturing process, low toxicity, and minimal susceptibility to photobleaching. Thus, investigating novel carbon dots is essential to identify optimal pH-sensitive candidates. In this study, five carbon dots were synthesized through a simple solvothermal treatment, and their fluorescence was examined as a function of pH within the range of 5-9, across an excitation range of 200-550 nm and an emission range of 250-750 nm. The resulting optical features showed that all five carbon dots exhibited pH sensitivity in both the UV and visible regions. One type of carbon dot, synthesized from m-phenylenediamine, displayed ratiometric properties at four excitation wavelengths, with the best results observed when excited in the visible spectrum at 475 nm. Indeed, these carbon dots exhibited good linearity over pH values of 6-9 in aqueous Carmody buffer solution by calculating the ratio of the green emission band at 525 nm to the orange one at 630 nm (I525nm/I630nm), demonstrating highly suitable properties for ratiometric sensing.
海洋酸化已成为气候变化方面一个需要持续监测的重大问题。此外，在工业领域，pH值监测也至关重要。因此，迫切需要开发出坚固且低成本的pH传感器。比率荧光pH传感作为一个很有前景的概念脱颖而出。碳点在荧光传感中的应用为推进pH传感解决方案提供了一条引人注目的途径。这种潜力得益于碳点价格低廉、制造工艺简单、毒性低以及光漂白敏感性小。因此，研究新型碳点对于确定最佳的pH敏感候选物至关重要。在本研究中，通过简单的溶剂热法合成了五种碳点，并在200 - 550 nm的激发范围和250 - 750 nm的发射范围内，考察了它们在5 - 9的pH范围内荧光随pH值的变化情况。所得光学特性表明，所有这五种碳点在紫外和可见光区域均表现出pH敏感性。由间苯二胺合成的一种碳点在四个激发波长下呈现比率特性，在475 nm的可见光谱激发时观察到最佳结果。实际上，通过计算525 nm处绿色发射带与630 nm处橙色发射带的比率（I525nm/I630nm），这些碳点在水相卡莫迪缓冲溶液中pH值为6 - 9时表现出良好的线性，显示出非常适合用于比率传感的特性。
