CSIRO Materials Science and Engineering, Bag 10, Clayton, VIC, 3169, Australia.
Adv Healthc Mater. 2013 Jun;2(6):836-45. doi: 10.1002/adhm.201200262. Epub 2013 Jan 7.
The mesoporous structure of sol-gel prepared gadolinium and europium doped silicate nanoparticles has been found to be highly dependent on the formulated composition, with synthesised samples displaying both disordered and hexagonally ordered mesoporous packing symmetry. The degree of pore ordering within the nanoparticles has a strong correlation with the total lanthanide (Gd(3+) and Eu(3+) ) concentration. The gadolinosilicates are excellent magnetic resonance imaging (MRI) longitudinal (T1 ) agents. The longitudinal relaxivity (r1 ) and transverse (r2 ) relaxivity, a measure of MRI contrast agent efficiency, were up to four times higher than the clinically employed Omniscan (gadodiamide); with r1 up to 20.6 s(-1) mM(-1) and r2 of 66.2 s(-1) mM(-1) compared to 5.53 and 4.64 s(-1) mM(-1) , respectively, for Omniscan. In addition, the europium content of all the samples studied is below the self-quenching limit, which results in a strong luminescence response from the nanoparticles on excitation at 250 nm. The Eu-Gd silicate nanoparticles act as bimodal imaging agents for MRI and luminescence. These mesoporous nanoparticles also have the potential to serve as encapsulation and controlled release matrices for pharmaceuticals. They are therefore a promising multimodal theranostic platform.
溶胶-凝胶法制备的掺镝和掺铕硅酸盐纳米粒子的介孔结构高度依赖于所制定的组成，合成的样品显示出无序和六方有序介孔堆积对称性。纳米粒子中孔有序度与总镧系元素（Gd(3+)和Eu(3+)）浓度密切相关。钆硅酸盐是优秀的磁共振成像（MRI）纵向（T1）造影剂。纵向弛豫率（r1）和横向（r2）弛豫率，MRI 造影剂效率的一种衡量标准，比临床使用的 Omniscan（钆喷酸葡胺）高 4 倍；r1 高达 20.6 s(-1) mM(-1)，r2 高达 66.2 s(-1) mM(-1)，而 Omniscan 的 r1 和 r2 分别为 5.53 和 4.64 s(-1) mM(-1)。此外，所有研究样品的铕含量均低于自猝灭极限，这导致纳米粒子在 250nm 激发下产生强烈的发光响应。Eu-Gd 硅酸盐纳米粒子可作为 MRI 和发光的双模成像剂。这些介孔纳米粒子还有可能作为药物的封装和控制释放基质。因此，它们是一种很有前途的多模式治疗平台。
