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The accurate therapeutic evaluation for chronic myeloid leukemia (CML) drug is of great importance to minimize side effects and enhance efficacy. Herein, a facile and precise surface-enhanced scattering (SERS) approach based on coupled plasmonic field has been introduced to evaluate the therapeutic outcomes of antileukemia drug through ultrasensitive assay of caspase-3 activity in apoptotic cells. Caspase-3 as an apoptosis indicator could specifically cleave the N-terminus of biotinylated DEVD-peptide (biotin-Gly-Asp-Gly-Asp-Glu-Val-Asp-Gly-Cys) immobilized on the Au nanoparticle-decorated TiO 2 nanotube arrays (TiO 2 /Au NTAs) substrate. After the enzyme cleavage with caspase-3, Raman-labelled Au nanostar (AuNS) probes captured the residual DEVD-peptides via the recognition between streptavidin and biotin, thus resulting in an enhanced Raman response on the SERS platform. The variation of Raman intensity revealed caspase-3 activity that reflected the chemotherapeutic effect. On this platform, AuNS nanoprobes offered a large number of binding sites and intrinsic “hot spots” for Raman reporters, while TiO 2 /Au NTAs rendered a homogenously coupled electromagnetic field between the adjacent repeated units over the large area. In particular, a spatially expanding plasmonic field formed by coupling AuNSs with TiO 2 /Au NTAs would further heighten Raman enhancement. Taking these advantages, the strong and uniform Raman signals were achieved. Furthermore, the practicability investigation witnessed that the proposed SERS strategy was available to evaluate the therapeutic effect of dasatinib on CML K562 cells. The developed method possesses fascinating advantages of cost-effectiveness, excellent reproducibility and high sensitivity, which endows it with promising potential in apoptosis monitoring and anticancer drug development. [ABSTRACT FROM AUTHOR]

Abstract: A sensitive colorimetric detection for biomolecules based on aptamer was described. Poly(dimethylsiloxane) (PDMS)–gold nanoparticles (AuNPs) composite film was used as a platform for immobilizing anti-target aptamer. PDMS–AuNPs composite film only covered with aptamer showed high inhibiting ability towards silver reduction, after target molecules were conjugated on the modified surface, the catalytic efficiency of AuNPs for silver reduction was increased. In this system, the darkness density of silver enhancement was applied for target quantitative measurement. Lysozyme and adenosine 5′-triphosphate (ATP) were tested as the models, quantitative measurements with imaging software or semiquantitative measurements with naked eyes were carried out in the range of 1×10−2–1μg/mL and 1×10−4–1×103 μg/mL, the volume of reagent using in each assay is 15μL or less. We speculated that aptamer-target conjugates’ inhibition ability for AuNPs’ catalytic efficiency toward silver reduction might come from charge and spatial effects. This study can offer a completely novel and relatively general approach for colorimetrical aptamer sensors with good analytical properties and potential applications. The sensor could be coupled with digital transmission of images for remote monitoring system in diagnosis, food control, and environmental analysis. [Copyright &y& Elsevier]

Abstract: The nanocomposite composed of carboxymethyl chitosan (CMCS) and gold nanoparticles was successfully prepared by a novel and in situ process. It was characterized by transmission electron microscopy (TEM) and Fourier transform infrared spectrophotometer (FTIR). The nanocomposite was hydrophilic even in neutral solutions, stable and inherited the properties of the AuNPs and CMCS, which make it biocompatible for enzymes immobilization. HRP, as a model enzyme, was immobilized on the silica sol–gel matrix containing the nanocomposite to construct a novel H2O2 biosensor. The direct electron transfer of HRP was achieved and investigated. The biosensor exhibited a fast amperometric response (5s), a good linear response over a wide range of concentrations from 5.0×10−6 to 1.4×10−3 M, and a low detection limit of 4.01×10−7 M. The apparent Michaelis–Menten constant () for the biosensor was 5.7×10−4 M. Good stability and sensitivity were assessed for the biosensor. [Copyright &y& Elsevier]