A surface-enhanced Raman scattering optrode prepared by in situ photoinduced reactions and its application for highly sensitive on-chip detection

Research progress on pesticide residue detection based on microfluidic technology

The problem of pesticide residue contamination has attracted widespread attention and poses a risk to human health. The current traditional pesticide residue detection methods have difficulty meeting rapid and diverse field screening requirements. Microfluidic technology integrates functions from sample preparation to detection, showing great potential for quick and accurate high-throughput detection of pesticide residues. This paper reviews the latest research progress on microfluidic technology for pesticide residue detection. First, the commonly used microfluidic materials are summarized, including silicon, glass, paper, polydimethylsiloxane, and polymethyl methacrylate. We evaluated their advantages and disadvantages in pesticide residue detection applications. Second, the current pesticide residue detection technology based on microfluidics and its application to real samples are summarized. Finally, we discuss this technology's present challenges and future research directions. This study is expected to provide a reference for the future development of microfluidic technology for pesticide residue detection.

Self-assembly on optical fibers: a powerful nanofabrication tool for next generation "lab-on-fiber" optrodes

Self-assembly offers a unique resource for the preparation of discrete structures at the nano- and microscale, which are either not accessible by other fabrication techniques or require highly expensive and technologically demanding processes. The possibility of obtaining spontaneous organization of separated components, whether they are molecules, polymers, nano- or micro-objects, into a larger functional unit, enables the development of ready-to-use plug and play devices and components at lower costs. Expanding the applicability of self-assembly approaches at the nanoscale to non-conventional substrates would open up new avenues towards multifunctional platforms customized for specific applications. Recently, the combination of the amazing morphological and optical features of self-assembled patterns with the intrinsic properties of optical fibers to conduct light to a remote location has demonstrated the potentiality to open up new intriguing scenarios featuring unprecedented functionalities and performances. The integration of advanced materials and structures at the nanoscale with optical fiber substrates is the idea behind the so-called lab-on-fiber technology, which is an emerging technology at the forefront of nanophotonics and nanotechnology research. Self-assembly processes can have a key role in implementing cost-effective solutions suitable for the mass production of technologically advanced platforms based on optical fibers towards their real market exploitation. Novel lab-on-fiber optrodes would arise from the sustainable integration of functional materials at the nano- and microscale onto optical fiber substrates. Such devices are able to be easily integrated in hypodermic needles and catheters for in vivo theranostics and point-of-care diagnostics, opening up new frontiers in multidisciplinary technological development to be exploited in life science applications. This work is conceived to provide an overview of the latest strategies, based on self-assembly processes, which have been implemented for the realization of lab-on-fiber optrodes with particular emphasis on the perspectives and challenges that lie ahead. We discuss the main fabrication techniques and strategies aimed at developing new multifunctional optical fiber nanoprobes and their application in real scenarios. Finally, we highlight some of the other self-assembly processes that have not yet been applied to optical fiber sensors, but have the potentiality to be exploited in the fabrication of future lab-on-fiber devices.

Advancements in the preparation of high-performance liquid chromatographic organic polymer monoliths for the separation of small-molecule drugs

The various advantages of organic polymer monoliths, including relatively simple preparation processes, abundant monomer availability, and a wide application range of pH, have attracted the attention of chromatographers. Organic polymer monoliths prepared by traditional methods only have macropores and mesopores, and micropores of less than 50 nm are not commonly available. These typical monoliths are suitable for the separation of biological macromolecules such as proteins and nucleic acids, but their ability to separate small molecular compounds is poor. In recent years, researchers have successfully modified polymer monoliths to achieve uniform compact pore structures. In particular, microporous materials with pores of 50 nm or less that can provide a large enough surface area are the key to the separation of small molecules. In this review, preparation methods of polymer monoliths for high-performance liquid chromatography, including ultra-high cross-linking technology, post-surface modification, and the addition of nanomaterials, are discussed. Modified monolithic columns have been used successfully to separate small molecules with obvious improvements in column efficiency.

Macroporous materials: microfluidic fabrication, functionalization and applications

This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields.

Surface-enhanced Raman spectroscopy and microfluidic platforms: challenges, solutions and potential applications

The review provides an overview of the development in the field of surface-enhanced Raman spectroscopy combined with microfluidic platforms.

Fe3O4@Graphene Oxide@Ag Particles for Surface Magnet Solid-Phase Extraction Surface-Enhanced Raman Scattering (SMSPE-SERS): From Sample Pretreatment to Detection All-in-One

A multifunctional magnetic graphene surface-enhanced Raman scattering (SERS) substrate was fabricated successfully by the layer-by-layer assembly of silver and graphene oxide (GO) nanoparticles (NPs) on the magnetic ferroferric oxide particles (Fe3O4@GO@Ag). This ternary particle possesses magnetic properties, SERS activity, and adsorption ability simultaneously. Owing to the multifunction of this Fe3O4@GO@Ag ternary complex, we put forward a new method called a surface magnetic solid-phase extraction (SMSPE) technique, for the SERS detections of pesticide residues on the fruit peels. SMSPE integrates many sample pretreatment procedures, such as surface extraction, separation sample, and detection, all-in-one. So this method shows great superiority in simplicity, rapidity, and high efficiency above other standard methods. The whole detection process can be finished within 20 min including the sample pretreatment and SERS detection. Owing to the high density of Ag NPs, the detection sensitivity is high enough that the lowest detectable concentrations are 0.48 and 40 ng/cm(2) for thiram and thiabendazole, which are much lower than the maximal residue limits in fruit prescribed by the U.S. Environmental Protection Agency. This multifunctional ternary particle and its corresponding analytical method have been proven to be applicable for practical samples and also valuable for other surface analysis.

Design and preparation of a recyclable microfluidic SERS chip with integrated Au@Ag/TiO2 NTs

Design and preparation of a recyclable microfluidic SERS chip with integrated Au@Ag/TiO₂ NTs.

Note: A portable Raman analyzer for microfluidic chips based on a dichroic beam splitter for integration of imaging and signal collection light paths

An integrated and portable Raman analyzer featuring an inverted probe fixed on a motor-driving adjustable optical module was designed for the combination of a microfluidic system. It possesses a micro-imaging function. The inverted configuration is advantageous to locate and focus microfluidic channels. Different from commercial micro-imaging Raman spectrometers using manual switchable light path, this analyzer adopts a dichroic beam splitter for both imaging and signal collection light paths, which avoids movable parts and improves the integration and stability of optics. Combined with surface-enhanced Raman scattering technique, this portable Raman micro-analyzer is promising as a powerful tool for microfluidic analytics.

Analytical characterization using surface-enhanced Raman scattering (SERS) and microfluidic sampling

With the rapid development of analytical techniques, it has become much easier to detect chemical and biological analytes, even at very low detection limits. In recent years, techniques based on vibrational spectroscopy, such as surface enhanced Raman spectroscopy (SERS), have been developed for non-destructive detection of pathogenic microorganisms. SERS is a highly sensitive analytical tool that can be used to characterize chemical and biological analytes interacting with SERS-active substrates. However, it has always been a challenge to obtain consistent and reproducible SERS spectroscopic results at complicated experimental conditions. Microfluidics, a tool for highly precise manipulation of small volume liquid samples, can be used to overcome the major drawbacks of SERS-based techniques. High reproducibility of SERS measurement could be obtained in continuous flow generated inside microfluidic devices. This article provides a thorough review of the principles, concepts and methods of SERS-microfluidic platforms, and the applications of such platforms in trace analysis of chemical and biological analytes.