A minireview of recent developments in ozone detection using optical chemodosimeters

The development of optical chemodosimeters for ozone detection has been an important research subject in recent years because of the environmental and biological relevance of ozone. The design and development of ozone chemodosimeters, as well as their numerous applications from 2009 to 2022, have all been thoroughly covered in this minireview. In this review, chemodosimeters are categorised according to their distinctive reaction mechanism with ozone. The comparative data for each of these chemodosimeters have also been provided here. We have also discussed the difficulties and potential prospects of this fast-evolving discipline. To the best of our knowledge, this is the first review that has comprehensively analysed the progress made in the development of ozone chemodosimeters.

Rapid and sensitive online determination of ozone via gas-liquid chemiluminescence synergistically enhanced by graphene quantum dots and Triton X-100

The determination of the ozone concentration in the atmosphere is an urgent need but most current methods are limited by large-scale equipment or complex procedures. Herein, a gas-liquid chemiluminescence (GL-CL) assay based on a portable GL-CL detector platform was reported for the fast and sensitive online determination of ozone. Graphene quantum dots (GQDs) and Triton X-100 were employed to synergistically enhance the CL intensity of chromotropic acid (CA)-ozone. The increase was about seven-fold upon the addition of GQDs and Triton X-100. The potential enhancement mechanism was also investigated. The speculated CL enhancement mechanism was that GQDs could catalyze dissolved oxygen in the CA solution to produce more free radicals in the presence of UV-light, and these radicals converted CA into more active compounds that could react with ozone and emit photons. The free radicals, active compounds and luminophores were protected from water quenching by micelles produced by dissolving Triton X-100 in water and as a result, CL was markedly enhanced. Most importantly, the response time of the GL-CL detector platform towards ozone was less than 0.5 s. Based on this outcome, a GL-CL assay for detecting atmospheric ozone was successfully developed with a linear range from 0.1 to 150 ppbv and a detection limit of 0.02 ppbv. This work provides a rapid and sensitive method for the online measurement of ozone, and has great potential in environmental applications; the potential applications of GQDs and Triton X-100 in the field of GL-CL have also been highlighted.

Applications of SERS in the Detection of Stress-Related Substances

A wide variety of biotic and abiotic stresses continually attack plants and animals, which adversely affect their growth, development, reproduction, and yield realization. To survive under stress conditions, highly sophisticated and efficient tolerance mechanisms have been evolved to adapt to stresses, which consist of the variation of effector molecules playing vital roles in physiological regulation. The development of a sensitive, facile, and rapid analytical methods for stress factors and effector molecules detection is significant for gaining deeper insight into the tolerance mechanisms. As a nondestructive analysis technique, surface-enhanced Raman spectroscopy (SERS) has unique advantages regarding its biosensing applications. It not only provides specific fingerprint spectra of the target molecules, conformation, and structure, but also has universal capacity for simultaneous detection and imaging of targets owing to the narrow width of the Raman vibrational bands. Herein, recent progress on biotic and abiotic stresses, tolerance mechanisms and effector molecules is summarized. Moreover, the development and promising future trends of SERS detection for stress-related substances combined with nanomaterials as substrates and SERS tags are discussed. This comprehensive and critical review might shed light on a new perspective for SERS applications.

A new silver nanochain SERS analytical platform to detect trace hexametaphosphate with a rhodamine S molecular probe

Using AgNO3 as the precursor, stable silver nanochain (AgNC) sols, orange-red in color, were prepared using hydrazine hydrate. A strong surface plasmon resonance Rayleigh scattering (RRS) peak occurred at 420 nm plus two surface plasmon resonance (SPR) absorption peaks at 410 nm and 510 nm. Rhodamine S (RhS) cationic dye was absorbed on the as-prepared AgNC substrate to obtain a RhS-AgNC surface-enhanced Raman scattering (SERS) nanoprobe that exhibited a strong SERS peak at 1506 cm(-1) and a strong RRS peak at 375 nm. Upon addition of the analyte sodium hexametaphosphate (HP), it reacted with RhS, which resulted in a decrease in the SERS and RRS peaks that was studied in detail. The decreased SERS and RRS intensities correlated linearly with HP concentration in the range of 0.0125-0.3 µmol/L and 0.05-1.0 µmol/L, with a detection limit of 6 nmol/L and 20 nmol/L HP respectively. Due to advantages of high sensitivity, good selectivity and simple operation, the RhS molecular probes were used to determine HP concentration in real samples.

SERS quantitative analysis of trace HSA with a Coomassie brilliant blue G-250 molecular probe in nanogold sol substrate

A SERS quantitative analysis method was developed for the detection of trace HSA with a Coomassie brilliant blue G-250 probe in nanogold sol substrate.

SERS quantitative detection of trace human chorionic gonadotropin using a label-free Victoria blue B as probe in the aggregated immunonanogold sol substrate

Nanogold particles (NG) were modified by anti-rabbit antibody (RAb) against human chorionic gonadotropin to obtain an immunonanogold probe (ING). In pH 7.0 Na2HPO4-citrate buffer solution containing KCl, ING probes formed large aggregates in which Victoria blue B (VBB) molecules were adsorbed on the surface and which exhibited strong surface-enhanced Raman scattering (SERS) at a peak of 1612 cm(-1). After addition of human chorionic gonadotropin (hCG) an immune reaction with the ING probe occurred to form dispersive ING-hCG complexes with non-SERS activity that led to a decreased SERS peak at 1612 cm(-1). The decreased SERS intensity was linear to the concentration of hCG over 2.4-73.2 ng/mL. The ING reaction was studied in detail by SERS, scanning electron microscope (SEM), resonance Rayleigh scattering (RRS), surface plasmon resonance (SPR) absorption and laser scattering techniques. SERS quenching was observed and discussed.

Utilization of triangle nanosilver to prepare spherical nanosilver and quantitatively detect trace titanium by SERS

The blue triangle nanosilver (BAgNP) sol was prepared by the two reducers of NaBH4 and H2O2. Using BAgNP as the precursor, a small spherical nanosilver (AgNP) sol in yellow was synthesized by addition of suitable amounts of X (-) (X = Cl, Br, and I). The oxidization process of BAgNP to AgNP was studied in detail by resonance Rayleigh scattering (RRS), surface-enhanced Raman scattering (SERS), laser scattering, surface plasmon resonance (SPR) absorption, and microscope techniques. It has been observed that NaCl accelerated the oxidizing BAgNP to form AgNP, and an oxidizing mechanism and quasi-nanograting Raman-scattering enhanced mechanism were developed to explain the phenomena. Using the BAgNP sol as substrate and based on the catalysis of Ti(IV) on the BrO3 (-) oxidizing safranine T (ST) molecular probe with a strong SERS peak at 1,535 cm(-1), a new catalytic SERS quantitative method was developed for the determination of 1.0 to 100 ng/mL Ti, with a detection limit of 0.4 ng/mL.