Molecular Photonics Group, Van't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, PO Box 94157, 1090 GD, Amsterdam, The Netherlands.
Molecular Cytology (MC), van LeeuwenHoek Centre for Advanced Microscopy (LCAM), University of Amsterdam, PO Box 1212, 1000 BE, Amsterdam, The Netherlands.
Photochem Photobiol Sci. 2024 Sep;23(9):1641-1657. doi: 10.1007/s43630-024-00618-2. Epub 2024 Sep 2.
The long-lived green luminescence of human bone (that has been heated to 600 °C for a short duration) is attributed to a carbon quantum dot material (derived from collagen) encapsulated and protected by an inorganic matrix (derived from bone apatite) and is more intense in dense rigid and crystalline parts of (healthy) human bones. The strong collagen-apatite interaction results (upon decomposition) in a protective inorganic environment of the luminescent centers allowing long-lived triplet-based emission of a carbon (quantum) dot-like material at room temperature, as well as resilience against oxidation between 550 and 650 °C. The graphitic black phase (obtained upon heating around 400 °C) is a precursor to the luminescent carbon-based material, that is strongly interacting with the crystalline inorganic matrix. Human bone samples that have been heated to 600 °C were subjected to steady-state and time-resolved spectroscopy. Excitation-emission matrix (EEM) luminescence spectroscopy revealed a broad range of excitation and emission wavelengths, indicating a heterogeneous system with a broad density of emissive states. The effect of low temperature on the heat-treated bone was studied with Cryogenic Steady State Luminescence Spectroscopy. Cooling the bone to 80 K leads to a slight increase in total emission intensity as well as an intensity increase towards to red part of the spectrum, incompatible with a defect state model displaying luminescent charge recombination in the inorganic matrix. Time-resolved spectroscopy with an Optical Multichannel Analyzer (OMA) and Time Correlated Single Photon Counting (TCSPC) of these samples showed that the decay could be fitted with a multi-exponential decay model as well as with second-order decay kinetics. Confocal Microscopy revealed distinct (plywood type) structures in the bone and high intensity-fast decay areas as well as a spatially heterogeneous distribution of green and (fewer) red emissive species. The use of the ATTO 565 dye aided in bone-structure visualization by chemical adsorption. Conceptually our data interpretation corresponds to previous reports from the material science field on luminescent powders.
人类骨骼（经短时间加热至 600°C）的长寿命绿色发光归因于一种碳量子点材料（源自胶原蛋白），被无机基质（源自骨磷灰石）包裹和保护，在（健康）人类骨骼的致密、刚性和结晶部分更为强烈。强的胶原-磷灰石相互作用导致（在分解时）发光中心的保护性无机环境，允许室温下基于三重态的碳（量子）点样材料的长寿命发射，以及在 550 至 650°C 之间的氧化抗性。在加热至约 400°C 时获得的石墨黑相是发光碳基材料的前体，它与结晶无机基质强烈相互作用。已加热至 600°C 的人类骨骼样品进行了稳态和时间分辨光谱分析。激发-发射矩阵（EEM）发光光谱显示出广泛的激发和发射波长，表明具有广泛发射态密度的非均匀体系。低温对热处理骨骼的影响通过低温稳态发光光谱进行了研究。将骨骼冷却至 80 K 会导致总发射强度略有增加，并且光谱的红色部分强度增加，这与显示在无机基质中发光电荷复合的缺陷态模型不兼容。使用光学多通道分析仪（OMA）和时间相关单光子计数（TCSPC）对这些样品进行时间分辨光谱分析表明，衰减可以用多指数衰减模型以及二阶衰减动力学来拟合。共焦显微镜显示骨骼中存在明显的（胶合板类型）结构以及高强度-快速衰减区域，以及绿色和（较少）红色发射物质的空间异质分布。使用 ATTO 565 染料通过化学吸附有助于骨骼结构可视化。从概念上讲，我们的数据解释与材料科学领域关于发光粉末的先前报告相对应。
