Biological mineralized tissues are hybrid materials with complex hierarchical architecture composed of biominerals often embedded in an organic matrix. The atomic-scale comprehension of surfaces and organo-mineral interfaces of these biominerals is of paramount importance to understand the ultrastructure, the formation mechanisms as well as the biological functions of the related biomineralized tissue. In this communication we demonstrate the capability of DNP SENS to reveal the fine atomic structure of biominerals, and more specifically their surfaces and interfaces. For this purpose, we studied two key examples belonging to the most significant biominerals family in nature: apatite in bone and aragonite in nacreous shell. As a result, we demonstrate that DNP SENS is a powerful approach for the study of intact biomineralized tissues. Signal enhancement factors are found to be up to 40 and 100, for the organic and the inorganic fractions, respectively, as soon as impregnation time with the radical solution is long enough (between 12 and 24 h) to allow an efficient radical penetration into the calcified tissues. Moreover, ions located at the biomineral surface are readily detected and identified through ³¹P or ¹³C HETCOR DNP SENS experiments. Noticeably, we show that protonated anions are preponderant at the biomineral surfaces in the form of HPO₄²⁻ for bone apatite and HCO₃²⁻ for nacreous aragonite. Finally, we demonstrate that organo-mineral interactions can be probed at the atomic level with high sensitivity. In particular, reliable ¹³C-{³¹P} REDOR experiments are achieved in a few hours, leading to the determination of distances, molar proportion and binding mode of citrate bonded to bone mineral in native compact bone. According to our results, only 80% of the total amount of citrate in bone is directly interacting with bone apatite through two out of three carboxylic groups.

生物矿化组织是杂种材料，具有复杂的层次结构，通常由嵌入有机基质中的生物矿物组成。这些生物矿物质的表面和有机矿物质界面的原子尺度理解对于了解相关生物矿化组织的超微结构，形成机理以及生物学功能至关重要。在本交流中，我们展示了DNP SENS揭示生物矿物的精细原子结构的能力，尤其是其表面和界面的能力。为此，我们研究了自然界中最重要的生物矿物质家族的两个关键实例：骨中的磷灰石和珍珠质的壳中的文石。结果，我们证明了DNP SENS是研究完整的生物矿化组织的有力方法。一旦自由基溶液的浸渍时间足够长（在12至24小时之间）以允许有效的自由基渗透到有机溶剂中，发现有机和无机部分的信号增强因子分别高达40和100。钙化组织。而且，位于生物矿物质表面的离子易于通过检测和识别³¹ P或¹³ C HETCOR DNP SENS实验。值得注意的是，我们显示质子化阴离子在生物矿物表面上占优势，对于骨磷灰石而言为HPO ₄ ^2-，对于珍珠质文石为HCO ₃ ^2-。最后，我们证明可以在原子水平上以高灵敏度探测有机-矿物相互作用。特别是可靠的¹³ C- { ³¹P} REDOR实验在几个小时内就完成了，从而确定了柠檬酸根与天然致密骨中的骨矿物结合的距离，摩尔比例和结合方式。根据我们的结果，骨骼中柠檬酸总量的仅80％通过三个羧基中的两个直接与骨磷灰石相互作用。