Adam_bluto

Publication date: August 2017
Source:Sensors and Actuators B: Chemical, Volume 247
Author(s): Yi-Wei Wang, Liye Chen, Mingfang Liang, Hui Xu, Shurong Tang, Huang-Hao Yang, Hongbo Song
A novel fluorescence immunoassay has been developed for alpha-fetoprotein (AFP) detection based on copper ions (Cu²⁺) regulated formation of quantum dots in situ. In place of traditionally used fluorophore or enzyme for signal amplification, CuO nanoparticles (NPs) were used as signal amplifier to enhance the detection sensitivity. In the presence of AFP, CuO NPs-labeled antibody can be specifically captured through the sandwich-type immunoreaction. By the use of l-cysteine (Cys) as stabilizer, aqueous fluorescent CdS quantum dots (QDs) can be formed by a facile synthesis method. After acid dissolution, numerous Cu²⁺ ions were released from the CuO NPs, which can act as catalyst to catalyze the oxidization of Cys and thus greatly reduce the amount of CdS QDs formed. The fluorescence intensity showed a good linear relationship with the AFP concentration in the range from 1 to 80ng/mL, as low as 0.45ng/mL AFP can be detected. The high throughput, disposability, sensitivity and accuracy of the proposed fluorescence immunoassay showed good applicability in clinical diagnosis.

Graphical abstract

Publication date: 4 February 2016
Source:Analytica Chimica Acta, Volume 906
Author(s): Manman Dong, Xia Liu, Qian Dang, Honglan Qi, Yin Huang, Qiang Gao, Chengxiao Zhang
A novel, sensitive and versatile electrogenerated chemiluminescence biosensing platform is developed for monitoring activity and inhibition of protein kinase based on Ru(bpy)3 ²⁺ functionalized gold nanoparticles (Ru(bpy)3 ²⁺-AuNPs) mediated signal transduction. Ru(bpy)3 ²⁺-AuNPs were formed by functionalizing AuNPs with Ru(bpy)3 ²⁺ through electrostatic interactions and were used as thiol-versatile signal probe. Casein kinase II (CK2) and cAMP-dependent protein kinase (PKA), two classical protein kinase implicated in disease, were chosen as model protein kinases while a CK2-specific peptide (CRRRADDSDDDDD) and a PKA-specific peptide (CLRRASLG) were employed as molecular substrate for CK2 and PKA, respectively. The specific peptide was self-assembled onto the gold electrode via Au–S bond to form ECL biosensor. Upon thiophosphorylation of the peptide on the electrode in the presence of protein kinase and co-substrate adenosine-5’-(γ-thio)-triphosphate, Ru(bpy)3 ²⁺-AuNPs was assembled onto the thiophosphorylated peptides via Au–S bond. The Ru(bpy)3 ²⁺-AuNPs attached on electrode surface produce detectable ECL signal in the presence of coreactant tripropylamine. This strategy is promising for multiple protein kinase assay and kinase inhibitor profiling with high sensitivity, good selectivity and versatility. The ECL intensity is proportional to the activity of CK2 in the range of 0.01–0.5 unit/mL with a low detection limit of 0.008 unit/mL and to the activity of PKA in the range of 0.01–0.4 unit/mL with a detection limit of 0.005 unit/mL. Additionally, this assay was applied to the detection of CK2 in serum samples and the inhibition of CK2 and PKA. This work demonstrates that the developed ECL method can provide a sensitive and versatile platform for the detection of kinase activity and drug-screening.

Graphical abstract