Chemiluminescence of off-line and on-line gold nanoparticle-catalyzed luminol system in the presence of flavonoid

A multi-responsive Au NCs@PMLE/Ca2+ antitumor hydrogel formed in situ on the interior/surface of tumors for PT imaging-guided synergistic PTT/O2-enhanced PDT effects

At present, although phototherapy and related imaging have proven to be promising cancer diagnosis and treatment strategies, the free diffusion of photosensitizers into normal tissues can cause side effects, and the efficiency of photodynamic therapy (PDT) can also be limited by the tumor hypoxic microenvironment. Herein, we designed and prepared a new cancer nanoplatform containing Au nanoclusters (NCs)@Premna microphylla leaf extract (PMLE) with both responsiveness to near-infrared (NIR) laser irradiation and tumor microenvironment (TME) by facile redox and coordination reactions. Then, the Au NCs@PMLE/Ca²⁺ hydrogel was constructed in situ inside and on the surface of tumors for locoregional antitumor activity under 808 nm laser irradiation. The Au NCs@PMLE nanoplatform showed distinguished performance in killing cancer cells and alleviating tumor hypoxia by enhancing the temperature of the tumor sites and producing reactive oxygen species (ROS) under NIR irradiation as well as catalyzing hydrogen peroxide (H₂O₂) decomposition in TME for oxygen (O₂) generation via catalase in PMLE. The ultra-small size of about 3 nm of the Au NCs in this nanoplatform was obtained using the biological molecules present in PMLE as reductants and coordination agents simultaneously, which also demonstrated the outstanding capability of photothermal (PT) imaging and photothermal therapy (PTT) towards tumors. Furthermore, the Au NCs@PMLE/Ca²⁺ hydrogel formed in situ through natural PMLE and intrinsic Ca²⁺ in TME could not only improve the biocompatibility of the nanoplatform and stability of Au NCs but was also highly concentrated around the tumor thus enhancing the therapeutic efficiency and inhibiting its migration to normal tissues, decreasing the side effects. The results of the experiments confirmed that the Au NCs@PMLE/Ca²⁺ hydrogel possessed PT imaging-guided NIR laser/TME-responsive synergetic cancer PTT/O₂-enhanced PDT and remarkable locoregional antitumor effect for cancer therapy. This work may open a new versatile route for multi-responsive localized cancer therapeutic nanoplatforms.

Natural catalyst for Luminol chemiluminesence - Application to validate peroxide levels in commercial hair dyes

Herein, we report hydrothermally treated green leaves (Moringa Oleifera) extract exploited as an efficient and highly-sensitive catalyst to catalyse the Chemiluminescence (CL) reaction of luminol. In the absence of enhancer, this green and hydrothermally treated catalyst (GHT) was found to significantly enhance the CL intensity about 3.5 fold as compared to the traditionally used K₃ Fe(CN)₆ catalyst. The structure and surface morphology of the catalyst was elucidated by XPS, SEM, XRD and Raman spectroscopy. The synergistic effect of the catalyst in the CL reaction was systematically investigated in the presence of hydrogen peroxide using UV Visible and chemiluminesence spectroscopy. Studies show that the sensitivity of the catalyst could be amplified by adjusting several parameters such as pH of the medium, concentrations of the base and luminol. The sensitivity of the novel-type catalyst was examined through the validation of hydrogen peroxide levels in the commercial hair dye samples. Remarkably, the catalyst displayed ultra-sensitivity to hydrogen peroxide as the limit of detection (LOD) of H₂ O₂ using this catalyst is determined to be 0.02 μM under optimized conditions. In general, the proposed inexpensive, eco-friendly, and non-toxic catalyst could enable the determination of the hydrogen peroxide for diverse analytical applications.

Nanomaterial-enhanced chemiluminescence reactions and their applications

Chemiluminescence (CL) analysis is a trace analytical method that possesses advantages including high sensitivity, wide linear range, easy operation, and simple instruments. With the development of nanotechnology, many nanomaterial (NM)-enhanced CL systems have been established in recent years and applied for the CL detection of metal ions, anions, small molecules, tumor markers, sequence-specific DNA, and RNA. This review summarizes the research progress of the nanomaterial-enhanced CL systems the past five years. These CL reactions include luminol, peroxyoxalate, lucigenin, ultraweak CL reactions, and so on. The CL mechanisms of the nanomaterial-enhanced CL systems are discussed in the first section. Nanomaterials take part in the CL reactions as the catalyst, CL emitter, energy acceptor, and reductant. Their applications are summarized in the second section. Finally, the challenges and opportunities are discussed.

Chemiluminescence of 3-aminophthalic acid anion-hydrogen peroxide-cobalt (II)

The 3-aminophthalic acid anion is a light emitter in luminol chemiluminescence. In the present study, the chemiluminescence of the 3-aminophthalic acid anion itself in the presence of hydrogen peroxide-cobalt (II) was studied. The results indicated that 3-aminophthalic acid anion is highly chemiluminescent in the typical hydrogen peroxide-cobalt (II) system. The peak wavelength of this chemiluminescence and the kinetic profile of the 3-aminophthalic acid anion-hydrogen peroxide-cobalt (II) reaction showed similarity with that of luminol, but the chemiluminescence of 3-aminophthalic acid anion had a much lower background signal. In addition, the chemiluminescence mechanism of 3-aminophthalic acid anion-hydrogen peroxide-cobalt (II) was also discussed and speculated as the interaction between 3-aminophthalic acid anion and singlet oxygen.