This paper describes a visual sensor array for pattern recognition analysis of proteins based on two different optical signal changes: colorimetric and fluorometric, by using two types of novel blue-emitting collagen protected gold nanoclusters and macerozyme R-10 protected gold nanoclusters with lower synthetic demands. Eight proteins have been well-discriminated by this visual sensor array, and protein mixtures after one-dimensional polyacrylamide gel electrophoresis also could be well-discriminated. The possible mechanism of this sensor array was illustrated and validated by fluorescence spectra, X-ray photoelectron spectroscopy (XPS), fluorescence lifetime, isothermal titration calorimetry (ITC), and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) experiments. It was attributed to that the adsorption of proteins onto the surface of gold nanoclusters (Au NCs), forming the protein-Au NCs complex. Furthermore, serums from normal and hepatoma patients were also effectively discriminated by this visual sensor array, showing feasible potential for diagnostic applications.

There are only a few systematic rules about how to selectively control the formation of DNA-templated metal nanoparticles (NPs) by varying sequence combinations of double-stranded DNA (dsDNA), although many attempts have been made. Herein, we develop a facile method for sequence-dependent formation of fluorescent CuNPs by using dsDNA as templates. Compared with random sequences, AT sequences are better templates for highly fluorescent CuNPs. Other specific sequences, for example, GC sequences, do not induce the formation of CuNPs. These results shed light on directed DNA metallization in a sequence-specific manner. Significantly, both the fluorescence intensity and the fluorescence lifetime of CuNPs can be tuned by the length or the sequence of dsDNA. In order to demonstrate the promising practicality of our findings, a sensitive and label-free fluorescence nuclease assay is proposed.

A novel fluorescence resonance energy transfer (FRET)-based platform using polydopamine nanospheres (PDANSs) as energy acceptors and dual colored Au NCs as energy donors for simultaneous detection of multiple tumor-related microRNAs with DNase-I-assisted target recycling amplification was developed for the first time. On the basis of monitoring the change of the recovered fluorescence intensity at 445 and 575 nm upon the addition of targets miRNA-21 and let-7a, these two microRNAs (miRNAs) can be simultaneously quantitatively detected, with detection limits of 4.2 and 3.6 pM (3σ) for miRNA-21 and let-7a, which was almost 20 times lower than that without DNase I. Additionally, semiquantitative determination of miRNA-21 and let-7a can also be realized through photovisualization. Most importantly, serums from normal and breast cancer patients can be visually and directly discriminated without any sample pretreatment by confocal microscope experiments, demonstrating promising potential for auxiliary clinical diagnosis.