Green and shape-tunable synthesis of ellagic acid crystalline particles by tannic acid for neuroprotection against oxidative stress.

Oxidative stress (OS) plays an important role in the emergence and prevention of neurodegenerative diseases, such as Alzheimer's disease (AD). Excess reactive oxygen species (ROS) accumulated in a neuronal cell can lead to OS, producing cell injury and death. Seeking nanoantioxidants against AD-related oxidative stress has attracted a lot of attention, especially those potential antioxidant agents derived from natural polyphenols. However, the transformation of abundant plant polyphenols to antioxidative biomaterials against OS is still challenging. In this work, we report a new method to transform amorphous tannic acid (TA) into tailorable shaped ellagic acid (EA) crystalline particles without using an organic solvent. EA crystalline particles were generated from TA, which underwent a chemical transformation, in situ metal phenolic coordination and acid-induced assembly process, and the size and shape could be controlled by varying the amount of acid. As-prepared EA crystalline particles showed excellent stability in water and lysosomal mimicking fluid and possess unique fluorescence properties and a strong response in mass spectrometry, which is beneficial for their imaging analysis in cells and tissues. More importantly, EA particles have shown significant H2O2-related ROS scavenging ability, a high cellular uptake capacity, an excellent neuroprotective effect in PC12 cells, a high drug loading capacity and BBB permeability to enter the brain. Our study suggested that the EA crystalline particles show great potential for OS-mediated AD treatment.

Triple Sensing Modes for Triggered ß-Galactosidase Activity Assays Based on Kaempferol-Deduced Silicon Nanoparticles and Biological Imaging of MCF-7 Breast Cancer Cells.

ß-Galactosidase (ß-Gala) is an essential biomarker enzyme for early detection of breast tumors and cellular senescence. Creating an accurate way to monitor ß-Gala activity is critical for biological research and early cancer detection. This work used fluorometric, colorimetric, and paper-based color sensing approaches to determine ß-Gala activity effectively. Via the sensing performance, the catalytic activity of ß-Gala resulted in silicon nanoparticles (SiNPs), fluorescent indicators obtained via a one-pot hydrothermal process. As a standard enzymatic hydrolysis product of the substrate, kaempferol 3-O-ß-d-galactopyranoside (KOßDG) caused the fluorometric signal to be attenuated on kaempferol-silicon nanoparticles (K-SiNPs). The sensing methods demonstrated a satisfactory linear response in sensing ß-Gala and a low detection limit. The findings showed the low limit of detection (LOD) as 0.00057 and 0.098 U/mL for fluorometric and colorimetric, respectively. The designed probe was then used to evaluate the catalytic activity of ß-Gala in yogurt and human serum, with recoveries ranging from 98.33 to 107.9%. The designed sensing approach was also applied to biological sample analysis. In contrast, breast cancer cells (MCF-7) were used as a model to test the in vitro toxicity and molecular fluorescence imaging potential of K-SiNPs. Hence, our fluorescent K-SiNPs can be used in the clinic to diagnose breast cellular carcinoma, since they can accurately measure the presence of invasive ductal carcinoma in serologic tests.

A novel "Turn-on" fluorometric assays triggered reaction for ß-glucosidase activity based on quercetin derived silicon nanoparticles and its potential use for cell imaging.

ß-Glucosidase (ß-Gluco) is an enzyme that is crucial to numerous diseases, including cancer, and in sector of industries, it is used in the manufacturing of food. Measuring its enzymatic activity is critical for biomedical studies and other activities. Herein, we have developed a novel and precise fluorescent sensing method for measuring ß-Gluco activity based on the production of yellow-green fluorescent quercetin-silicon nanoparticles (Q-SiNPs) produced from quercetin (QN) as a reducing agent and 3-[2-(2-aminoethyl amino) ethylamino] propyl-trimethoxy silane (AEEA) as a silane molecule. ß-Gluco hydrolyzed quercetin-3-O-ß-d-glucopyranoside (QO-ß-DG) to produce QN, which was then used to produce Q-SiNPs. Reaction parameters, including temperature, time, buffer, pH, and probe concentration, were carefully tuned in this study. Subsequently, the fluorescence intensity was performed, showing good linearity (R2 = 0.989), a broad linear dynamic range between 0.5 and 12 U L-1, and a limit of detection (LOD) as low as 0.428 U L-1, which was proven by fluorescence measurements. Most importantly, various parameters were detected and characterized with or without ß-Gluco. The designed probe was successively used to assess ß-Gluco activity in human serum and moldy bread. However, the mathematical findings revealed recoveries for human serum ranging from 99.3 to 101.66% and for moldy bread from 100.11 to 102.5%. Additionally, Q-SiNPs were well suited to being incubated in vitro with L929 and SiHa living cells, and after using an Olympus microscope, imaging showed good fluorescence cell images, and their viability evinced minimal cytotoxicity of 77% for L929 and 88% for SiHa. The developed fluorescence biosensor showed promise for general use in diagnostic tests. Therefore, due to this outstanding sensing modality, we anticipate that this research can provide a novel schematic project for creating simple nanostructures with a suitable plan and a green synthetic option for enzyme activity and cell imaging.

Green-emitting functionalized silicon nanoparticles as an "off-on" fluorescence bio-probe for the sensitive and selective detection of mercury (II) and 3-mercaptopropionic acid.

Herein, we developed a class of functionalized silicon nanoparticles (F-SiNPs) bio-probes named thiol-conjugated F-SiNPs. They combine excellent biocompatibility with small dimensions (<10 nm) and biological usefulness with sustained and robust fluorescence (3.32% photoluminescent quantum yield). Identifying 3-Mercaptopropionic acid (3-MPA), which lowers the quantity of gamma-aminobutyric acid in the brain, and mercury (Hg2+) was a crucially important step since their excessive levels are a sign of several disorders. Using F-SiNPs as a fluorescent bio-probe, we provided an "off-on" technique for sensitively and selectively determining Hg2+ and 3-MPA in this study. The 3-(2-aminoethylamino) propyl (dimethoxymethylsilane) and basic fuchsin as precursors were hydrothermally treated to produce the F-SiNPs exhibiting green fluorescence. Our results suggest that Hg2+ reduced the fluorescence of F-SiNPs because of strong ionic interactions and metal-ligand binding among many thiols and carboxyl groupings at the surface of Hg2+ and F-SiNPs. Additionally, the resultants demonstrated that after being quenched by Hg2+, the produced F-SiNPs led to the distinctive "off-on" response to 3-MPA. Moreover, the method could detect Hg2+ and 3-MPA with limits of detection of 0.065 µM and 0.017 µM, respectively. The technique employed is quick, easy, affordable, and environmentally friendly. The sensing platform has successfully determined Hg2+ and 3-MPA in urine, water, and human serum samples.

Preparation of Electrospun Active Molecules Membrane Application to Atmospheric Free Radicals.

Atmospheric reactive oxygen species (ROS) play a key role in the process of air pollution and oxidative damage to organisms. The analysis of ROS was carried out by the capture-derivative method. Therefore, it is necessary to prepare an effective molecular membrane to trap and detect ROS. Electrospinning membranes were prepared by combining the electrospinning technique with chrysin, baicalein, scutellarin, genistein, quercetin, and baicalin. By comparing the structures of the membranes before and after the reaction, the fluorescence enhancement characteristics of the reactive molecular membranes and the atmospheric radicals were studied. The ability of the active molecular membranes to trap atmospheric radicals was also studied. It was found that the genistein active molecular membrane had good trapping ability in four environments. The fluorescence enhancement rates in ROS, OH radical and O3 simulated environments were 39.32%, 7.99% and 11.92%, respectively. The fluorescence enhancement rate in atmospheric environment was 16.16%. Indeed, the sites where the atmospheric radicals react with the active molecular membranes are discussed. It is found that it is mainly related to the 5,7 phenolic hydroxyl of ring A, catechol structure and the coexistence structure of 4' phenolic hydroxyl of ring B and 7 phenolic hydroxyl of ring A. Therefore, the genistein molecular membrane has shown great potential in its trapping ability and it is also environmentally friendly.

Hydroxyl, hydroperoxyl free radicals determination methods in atmosphere and troposphere.

The hydroxyl radical (•OH) has a crucial function in the oxidation and removal of many atmospheric compounds that are harmful to health. Nevertheless, high reactivity, low atmospheric abundance, determination of hydroxyl, and hydroperoxyl radical's quantity is very difficult. In the atmosphere and troposphere, hydroperoxyl radicals (HO2) are closely demanded in the chemical oxidation of the troposphere. But advances in technology have allowed researchers to improve the determination methods on the research of free radicals through some spectroscopic techniques. So far, several methods such as laser-induced fluorescence (LIF), high-performance liquid chromatography (HPLC), and chemical ionization mass spectroscopy have been identified and mostly used in determining the quantity of hydroxyl and hydroperoxyl radicals. In this systematic review, we have advised the use of scavenger as an advance for further researchers to circumvent some of these problems caused by free radicals. The primary goal of this review is to deepen our understanding of the functions of the most critical free radical (•OH, HO2) and also understand the currently used methods to quantify them in the atmosphere and troposphere.