Plasmonic nanostructures possessing unique and versatile optoelectronic properties have been vastly investigated over the past decade. However, the full potential of plasmonic nanostructure has not yet been fully exploited, particularly with single-component homogeneous structures with monotonic properties, and the addition of new components for making multicomponent nanoparticles may lead to new-yet-unexpected or improved properties. Here we define the term "multi-component nanoparticles" as hybrid structures composed of two or more condensed nanoscale domains with distinctive material compositions, shapes, or sizes. We reviewed and discussed the designing principles and synthetic strategies to efficiently combine multiple components to form hybrid nanoparticles with a new or improved plasmonic functionality. In particular, it has been quite challenging to precisely synthesize widely diverse multicomponent plasmonic structures, limiting realization of the full potential of plasmonic heterostructures. To address this challenge, several synthetic approaches have been reported to form a variety of different multicomponent plasmonic nanoparticles, mainly based on heterogeneous nucleation, atomic replacements, adsorption on supports, and biomolecule-mediated assemblies. In addition, the unique and synergistic features of multicomponent plasmonic nanoparticles, such as combination of pristine material properties, finely tuned plasmon resonance and coupling, enhanced light-matter interactions, geometry-induced polarization, and plasmon-induced energy and charge transfer across the heterointerface, were reported. In this review, we comprehensively summarize the latest advances on state-of-art synthetic strategies, unique properties, and promising applications of multicomponent plasmonic nanoparticles. These plasmonic nanoparticles including heterostructured nanoparticles and composite nanostructures are prepared by direct synthesis and physical force- or biomolecule-mediated assembly, which hold tremendous potential for plasmon-mediated energy transfer, magnetic plasmonics, metamolecules, and nanobiotechnology.

Multicomponent Plasmonic Nanoparticles: From Heterostructured Nanoparticles to Colloidal Composite Nanostructures.

Colorimetric sensors and biosensors exhibit promising potential toward the detection of metallic cations, anions, organic dyes, drugs, pesticides and other toxic pollutants due to their easy fabrication, quick detection, and high sensitivity and selectivity, as well as easy naked-eye sensing In this work, we present the recent advances (since 2014) made in the fabrication of colorimetric sensors for the environmental monitoring of toxic pollutants To understand the relationships between the type, structure, and functions of nanomaterials as building units and the sensing performance of the designed colorimetric sensors, the fabrication of several sensor platforms based on functional nanomaterials (such as metal nanoparticles, metal oxides, quantum dots, two-dimensional nanozymes, organic probes, and Schiff bases) are demonstrated and discussed The sensing mechanisms of the considered colorimetric sensors based on the aggregation of nanoparticles, decomposition of nanoparticles, nanozymes, fluorescence on–off, ligand–receptor interactions, and photonic structures are introduced and discussed in detail In addition, instrument-based colorimetric sensors and advanced colorimetric sensor products for high-performance environmental monitoring are presented Finally, the advantages and disadvantages of various colorimetric sensors in environmental monitoring are analyzed and compared It is expected that this work will be valuable for readers to understand the fabrication and sensing mechanisms of various colorimetric biosensors and promote their development in environmental science, materials science, nanotechnology, food science, and bioanalysis

Recent advances in the design of colorimetric sensors for environmental monitoring

Nitrogen-doped fluorescence carbon dots as multi-mechanism detection for iodide and curcumin in biological and food samples.

Lead(II) ion (Pb2+) contamination can be accumulated along the food chain and cause a serious threat to public health. Plenty of research effort has thus been devoted to the development of fast, sensitive and selective biosensors for monitoring Pb2+. Aptamer especially Pb2+ based DNAzymes (obtained from a large DNA library via in vitro selection) and DNA molecules are highly selective for a number of metal ions. Therefore, aptamer-based biosensors have been extensively studied for Pb2+ ion detection with a high sensitivity. In this review, we explain the current progress of Pb2+ aptamer-based sensors mainly in three groups: fluorescent; colorimetric; and electrochemical biosensors.

Aptamer-based biosensors for detection of lead(II) ion: a review

In this study, the silver nanoclusters (Ag NCs) with aggregation-induced emission property were synthesized successfully by reflux method using silver nitrate (AgNO3) as raw material and N-acetyl-L-cysteine (NAC) as the reductant and capped ligand. The synthesis process was simple, environmentally friendly and the process did not require the addition of other surfactants or common reductant such as sodium borohydride, ascorbic acid. The obtained Ag NCs possessed the special Ag(0)@Ag(I)–SR core-shell structure with aggregation-induced emission characteristic. The Ag NCs exhibited strong green luminescence with an optimal emission wavelength of 494 nm, high quantum yield of 0.44, microsecond long life of 11.07 μs and high content of Ag(I) component. In addition, the obtained Ag NCs were used to detect the tetracycline (TC) with the range of linearity from 1.12 μM to 230 μM and a detection limit of 0.47 μM on account of the quenching mechanism of the internal filtration effect (IFE) and the static quenching effect between tetracycline and Ag NCs. The proposed sensing method based on NAC@Ag NCs showed good sensitivity and selectivity for tetracycline, wide range of linearity, low detection limit and strong anti-interference ability. This method had been applied to detect tetracycline concentration reliably and accurately in actual sample milk.

Guofeng Xing

Papers

A novel fluorometric and colorimetric sensor for iodide determination using DNA-templated gold/silver nanoclusters.