pH-Sensitive MR Responses Induced by Dendron-Functionalized SPIONs.
pH-Sensitive MR Responses Induced by Dendron-Functionalized SPIONs.
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DOI：
10.1021/jp306128v
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发表时间：
2013-01-31
影响因子：
3.7
通讯作者：
Goodson, Boyd M.
中科院分区：
文献类型：
--
作者：
Saha, Indrajit;Chaffee, Kathleen E.;Duanmu, Chuansong;Woods, Brooke M.;Stokes, Ashley M.;Buck, Laura E.;Walkup, Laura L.;Sattenapally, Narsimha;Huggenvik, Jodi;Gao, Yong;Goodson, Boyd M.
我们报告了一系列调查的pH值敏感的磁共振（MR）响应的各种表面功能化的SPION（超顺磁性氧化铁纳米粒子）。首先，用三代不同的三聚氰胺-树枝化基元对~12 nm高度单晶SPION核进行官能化，以得到具有高摩尔弛豫率（例如，在7 T下R2 m ~300 mM−1·s−1，在0.5 T下R1 m ~20-30 mM−1·s−1）和优异的水稳定性的试剂。摩尔弛豫率被发现表现出极大的敏感性，pH值在生理相关的离子强度，观察到尖锐的拐点附近的三聚氰胺单体的pKa值的pH值。观察到效应的强度随着树枝化基元产生的增加而增长（伴随着主要pH拐点位置的偏移）。相反的行为R2 m和R2 m * 的趋势可以被利用，以提供一个比例的MR响应pH值。结合TEM和相应的MR测量从不同的离子强度的解决方案，这些结果是一致的pH值敏感的行为起源于瞬态的，可逆的SPION集群调制的SPION表面电荷密度和溶液离子强度之间的相互作用。还介绍了HeLa细胞培养物中SPION细胞摄取和MR响应的研究。最后，与具有替代功能的次氮基三乙酸或聚（1-乙烯基咪唑）的衍生物的SPION的MR响应的比较表明，这些类型的pH敏感的MR响应可以高度依赖于表面物种的化学组成（因此可以通过合理的设计进行调制）。
We report a series of investigations of the pH-sensitive magnetic resonance (MR) responses of various surface-functionalized SPIONs (superparamagnetic iron oxide nanoparticles). First, functionalization of ~12 nm highly monocrystalline SPION cores with three different generations of melamine-dendrons was optimized to give agents with high molar relaxivities (e.g. R2m~300 mM−1·s−1 at 7 T and R1m~20–30 mM−1·s−1 at 0.5 T) and excellent aqueous stabilities. Molar relaxivities were found to exhibit great sensitivity to pH at physiologically-relevant ionic strengths, with sharp inflections observed at pH values near the pKa of the melamine monomer. The strength of the effect was observed to grow with increasing dendron generation (with concomitant shift in the position of the main pH inflection). Opposing behavior in R2m and R2m* trends may be exploited to provide a ratiometric MR response to pH. Combined with TEM and corresponding MR measurements from solutions of varying ionic strengths, these results are consistent with the pH-sensitive behavior originating from transient, reversible SPION clustering modulated by an interplay between SPION surface charge density and solution ionic strength. Studies of SPION cellular uptake and MR response in HeLa cell cultures are also presented. Finally, comparisons with the MR responses of SPIONs with alternative functionalities—derivatives of nitrilotriacetic acid or poly(1-vinylimidazole)—indicate that these types of pH-sensitive MR responses can be highly dependent upon the chemical composition of the surface species (and thus amenable to modulation through rational design).
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影响因子：
2.9
作者：
Hashim, Arig Ibrahim;Zhang, Xiaomeng;Wojtkowiak, Jonathan W.;Martinez, Gary V.;Gillies, Robert J.
通讯作者：
Gillies, Robert J.
影响因子：
3.3
作者：
Ackerman, JJH;Soto, GE;Evelhoch, JL
通讯作者：
Evelhoch, JL
影响因子：
--
作者：
GILLIES, RJ;LIU, Z;BHUJWALLA, Z
通讯作者：
BHUJWALLA, Z
影响因子：
8.6
作者：
Duanmu, Chuansong;Saha, Indrajit;Gao, Yong
通讯作者：
Gao, Yong
影响因子：
3.3
作者：
Dahnke, Hannes;Liu, Wei;Herzka, Daniel;Frank, Joseph A.;Schaeffter, Tobias
通讯作者：
Schaeffter, Tobias