Integration of capillary electrophoresis with gold nanoparticle-based colorimetry

AuNPs-COFs Core-Shell Reversible SERS Nanosensor for Monitoring Intracellular Redox Dynamics

The redox homeostasis in living cells is greatly crucial for maintaining the redox biological function, whereas accurate and dynamic detection of intracellular redox states still remains challenging. Herein, a reversible surface-enhanced Raman scattering (SERS) nanosensor based on covalent organic frameworks (COFs) was prepared to dynamically monitor the redox processes in living cells. The nanosensor was fabricated by modifying the redox-responsive Raman reporter molecule, 2-Mercaptobenzoquione (2-MBQ), on the surface of gold nanoparticles (AuNPs), followed by the in situ coating of COFs shell. 2-MBQ molecules can repeatedly and quickly undergo reduction and oxidation when successively treated with ascorbic acid (AA) and hypochlorite (ClO^-) (as models of reductive and oxidative species, respectively), which resulted in the reciprocating changes of SERS spectra at 900 cm^-1. The construction of the COFs shell provided the nanosensor with great stability and anti-interference capability, thus reliably visualizing the dynamics of intracellular redox species like AA and ClO^- by SERS nanosensor. Taken together, the proposed SERS strategy opens up the prospects to investigate the signal transduction pathways and pathological processes related with redox dynamics.

Highly stable gold nanoparticles in an aqueous solution without any stabilizer prepared by a solution plasma process evaluated through capillary zone electrophoresis

Gold nanoparticles (AuNP) were prepared by a solution plasma process in the presence of H₂O₂, and they were dispersed in an aqueous solution without any stabilizer generally used. The dispersion stability of the AuNP in an aqueous solution was evaluated by capillary zone electrophoresis (CZE). An anionic broad peak was detected with the AuNP by CZE based on its wide variations in size and net charge. The broad peak also suggests that the AuNP were well dispersed in an aqueous solution. The dispersion stability of AuNP was evaluated from the viewpoints of long-term dispersion, salt concentration, and organic co-solvent. The anionic broad peak attributed to the dispersed AuNP was successfully detected for at least 55 weeks from the preparation with less shot signals of the aggregates. The AuNP was also well dispersed in aqueous NaCl solutions with its concentrations up to 30 mmol L^-1, as well as with ethanol co-solvent up to 40%(v/v). The AuNP prepared by the solution plasma process was proved to be highly stable in an aqueous solution.

Recent advances in nanomaterial-assisted detection coupled with capillary and microchip electrophoresis

Nanomaterials have drawn much attention because of their unique properties enabling them to play important roles in various applications in different areas. This review covers literature data in the Web of Science from January 2017 to August 2020, focusing on the applications of nanomaterials (nanoparticles, quantum dots, nanotubes, and graphene) in CE and MCE to achieve enhanced sensitivity of several detection techniques: fluorescence, colorimetry, amperometry, and chemiluminescence /electrochemiluminescence. For the articles surveyed, the types of nanomaterials used, detection mechanisms, analytical performance, and applications are presented and discussed.

Preparation of photosensitive diazotized poly (vinyl alcohol-b-styrene) covalent capillary coatings for capillary electrophoresis separation of proteins

In this paper, we have developed a novel method for the preparation of covalently connected capillary coatings in which diazotized poly (vinyl alcohol-b-styrene) (diazo-P(VA-b-St)) was used as a photosensitive coating agent. Firstly, the diazo-P(VA-b-St) coating was self-assembled on the inner surface of the capillary, and then irradiated by ultraviolet (UV) light to convert the ionic bonding into covalent bonding through the unique photochemical reaction of diazo groups. The covalently connected coatings inhibited the protein adsorption on the inner surface of the capillary, as a result, the baseline protein separation of ribonuclease A (RNase A), lysozyme (Lyz) and bovine serum albumin (BSA) were attained by utilizing the capillary electrophoresis (CE). The covalently connected diazo-P(VA-b-St) capillary coatings have greater CE separation performance with magnificent repeatability and enhanced stability, when compared with non-covalently coated or bare capillaries. This strategy to synthesize photosensitive diazo-P(VA-b-St) capillary coatings for their use in capillary electrophoresis separation of proteins is highly environment-friendly as it does not involve the use of extremely noxious and moisture penetrating coatings of silane.