21394-68-3Relevant articles and documents
A highly sensitive luminescent probe based on Ru(II)-bipyridine complex for Cu2+, L-Histidine detection and cellular imaging
Zhang, Shi-Ting,Li, Panpan,Liao, Caiyun,Luo, Tingting,Kou, Xingming,Xiao, Dan
, p. 161 - 169 (2018)
A ruthenium(II) bipyridyl complex conjugated with functionalized Schiff base (RuA) has been synthesized and functioned as a luminescent probe. The luminescence of RuA was greatly quenched by Cu2+ due to its molecular coordination with paramagnetic Cu2+. Subsequently, the addition of L-Histidine can turn on the luminescence of the RuA-Cu(II) ensemble, which can be attributed to the replacement of RuA in RuA-Cu(II) ensemble by L-Histidine. On the basis of the quenching and recovery of the luminescence of RuA, we proposed a rapid and highly sensitive on-off-on luminescent assay for sensing Cu2+ and L-Histidine in aqueous solution. Under the optimal conditions, Cu2+ and L-Histidine can be detected in the concentration range of 5 nM–9.0 μM and 50 nM–30 μM, respectively, and the corresponding detection limits were calculated to be 0.35 and 0.44 nM (S/N=3), separately. The proposed luminescent probe has been successfully utilized for the analysis of Cu2+ and L-Histidine in real samples (drinking water and biological fluids). Furthermore, the probe revealed good photostability, low cytotoxicity and excellent permeability, making it a suitable candidate for cell imaging and labeling in vitro.
Manipulation of Glutathione-Mediated Degradation of Thiol-Maleimide Conjugates
Wu, Haocheng,Levalley, Paige J.,Luo, Tianzhi,Kloxin, April M.,Kiick, Kristi L.
, p. 3595 - 3605 (2018/11/02)
The retro Michael-type addition and thiol exchange of thioether succinimide click linkages in response to thiol-containing environments offers a novel strategy for the design of glutathione-sensitive degradable hydrogels for controlled drug delivery. Here we characterize the kinetics and extent of the retro Michael-type addition and thiol exchange with changes in both the pKa of the thiols and the identity of N-substituents of maleimides. A series of N-substituted thioether succinimides were prepared through typical Michael-type addition. Model studies (1H NMR, HPLC) of 4-mercaptophenylacetic acid (MPA, pKa 6.6) conjugated to N-ethyl maleimide (NEM), N-phenyl maleimide (NPM), or N-aminoethyl maleimide (NAEM) and then incubated with glutathione showed half-lives of conversion from 3.1 to 18 h, with extents of conversion from approximately 12% to 90%. The variations in the rates of exchange and hydrolytic ring opening appear to be mediated by resonance effects, electron-withdrawing capacity of the N-substituted moiety, as well as the potential for intramolecular catalytic hydrogen bonding of amine substituents with water (particularly in the case of ring opening). Further model studies of 4-mercaptohydrocinnamic acid (MPP, pKa 7.0) and N-acetyl-l-cysteine (NAC, pKa 9.5) conjugated to selected N-substituted maleimides and then incubated with glutathione showed half-lives of conversion from 3.6 to 258 h, with extents of conversion from approximately 1% to 90%. A higher pKa of the thiol decreased the rate of the exchange reaction and limited the impact of other electronic effects of N-substituents on the extents of conversion. Additional factors affecting the conversion kinetics were studied on NEM conjugates. The kinetics of the retro Michael-type addition and exchange reaction were not hindered by thiol traps of lower pKa, but were retarded in conditions of lower pH. These studies shed light into details of thiol and maleimide design that could be used to tune the rates of degradation of drug and polymer conjugates for a variety of applications.
Tunable degradation of maleimide-Thiol adducts in reducing environments
Baldwin, Aaron D.,Kiick, Kristi L.
experimental part, p. 1946 - 1953 (2012/07/01)
Addition chemistries are widely used in preparing biological conjugates, and in particular, maleimide-thiol adducts have been widely employed. Here, we show that the resulting succinimide thioether formed by the Michael-type addition of thiols to N-ethylm
