Search

The production of bimetallic nanoparticles with ultrasmall sizes is the constant pursuit in chemistry and materials science because of their promising applications in catalysis, electronics and sensing. Here we report ambient-temperature preparation of bimetallic NPs with tunable size and composition using microfluidic-controlled co-reduction of two metal precursors on silicon surface. Instead of free diffusion of metal ions in bulk system, microfluidic flow could well control the local ions concentration, thus leading to homogenous and controllable reduction rate among different nucleation sites. By controlling precursor concentration, flow rate and reaction time, we rationally design a series of bimetallic NPs including Ag-Cu, Ag-Pd, Cu-Pt, Cu-Pd and Pt-Pd NPs with ultrasmall sizes (∼ 3.0 nm), tight size distributions (relative standard deviation (RSD) < 21%), clean surface, and homogenous elemental compositions among particles (standard deviation (SD) of weight ratios < 3.5%). This approach provides a facile, green and scalable method toward the synthesis of diverse bimetallic NPs with excellent activity.

Background Ex vivo and in vivo detection and imaging of adenosine triphosphate (ATP) is critically important for the diagnosis and treatment of diseases, which still remains challenges up to present. Results We herein demonstrate that ATP could be fluorescently detected and imaged ex vivo and in vivo. In particular, we fabricate a kind of fluorescent ATP probes, which are made of titanium carbide (TC) nanosheets modified with the ROX-tagged ATP-aptamer (TC/Apt). In the constructed TC/Apt, TC shows superior quenching efficiency against ROX (e.g., ~ 97%). While in the presence of ATP, ROX-tagged aptamer is released from TC surface, leading to the recovery of fluorescence of ROX under the 545-nm excitation. Consequently, a wide dynamic range from 1 μM to 1.5 mM ATP and a high sensitivity with a limit of detection (LOD) down to 0.2 μM ATP can be readily achieved by the prepared TC/Apt. We further demonstrate that the as-prepared TC/Apt probe is feasible for accurate discrimination of ATP in different samples including living cells, body fluids (e.g., mouse serum, mouse urine and human serum) and mouse tumor models. Conclusions Fluorescence detection and imaging of ATP could be readily achieved in living cells, body fluids (e.g., urine and serum), as well as mouse tumor model through a new kind of fluorescent ATP nanoprobes, offering new powerful tools for the treatment of diseases related to abnormal fluctuation of ATP concentration.

There currently exists increasing concerns on the development of a kind of high-performance SERS platform, which is suitable for sensing applications ranging from the molecular to cellular (e.g., bacteria) level. Herein, we develop a novel kind of universal SERS chip, made of graphene (G)-silver nanoparticle (AgNP)-silicon (Si) sandwich nanohybrids (G@AgNPs@Si), in which AgNPs are in situ grown on a silicon wafer through hydrofluoric acid-etching-assisted chemical reduction, followed by coating with single-layer graphene via a polymer-protective etching method. The resultant chip features a strong, stable, reproducible surface-enhanced Raman scattering (SERS) effect and reliable quantitative capability. By virtues of these merits, the G@AgNPs@Si platform is capable for not only molecular detection and quantification but also cellular analysis in real systems. As a proof-of-concept application, the chip allows ultrahigh sensitive and reliable detection of adenosine triphosphate (ATP), with a detection limit of ∼1 pM. In addition, the chip, serving as a novel multifunctional platform, enables simultaneous capture, discrimination, and inactivation of bacteria. Typically, the bacterial capture efficiency is 54% at 10

Rapid, sensitive, and accurate detection of adenosine triphosphate (ATP), the primary energy molecule, is critical for the elucidation of its unique roles in cell signaling and many cellular reactions. Up to date, a major challenge is still remaining for fabricating surface-enhanced Raman scattering (SERS) aptamer sensors (aptasensors) suitable for accurate and reliable quantification of ATP. Herein, we develop the ratiometric silicon SERS aptasensor for ATP detection, which is made of uniform silver nanoparticles (Ag NPs)-modified silicon wafer (Ag NPs@Si), followed by the functionalization with double-stranded DNA (dsDNA I). The dsDNA I is formed by the aptamer and its complementary DNA (cDNA), which contains two independent segments (e.g., 5'-Cy3-labeled DNA-C1, 3'-ROX-labeled DNA-C2). In the presence of ATP, ROX-DNA-C2 is dissociated from dsDNA I due to the formation of aptamer/ATP complex, leading to the attenuation of ROX signals, and meanwhile, Cy3 signals remain constant ascribed to the formation of dsDNA II caused by the supplementation of aptamer. As a result, ratiometric signals of the ratio of ROX intensity to Cy3 intensity (I