2-nitrobenzoic Acid Research Articles

Chip-Scale Aptamer Sandwich Assay Using Optical Waveguide-Assisted Surface-Enhanced Raman Spectroscopy

Chip-scale optical waveguide-assisted surface-enhanced Raman spectroscopy (SERS) that used nanoparticles (NPs) was demonstrated. The Raman signals from Raman reporter (RR) molecules on NPs can be efficiently excited by the waveguide evanescent field when the molecules are in proximity to the waveguide surface. The Raman signal was enhanced by plasmon resonance due to the NPs close to the waveguide surface. The optical waveguide mode and the NP-induced field enhancement were calculated using a finite difference method (FDM). The sensing performance of the waveguide-assisted SERS device was experimentally characterized by measuring the Raman scattering from various RRs, including 4-mercaptobenzoic acid (4-MBA), 5,5′-dithio-bis-(2-nitrobenzoic acid) (DTNB), and malachite green isothiocyanate (MGITC). The observed Raman spectral features were identified and assigned to the complex vibrational modes associated with different reporters. A low detection limit of 1 nM was achieved. In addition, the device sensing method was applied to the detection of the biomarker cardiac troponin I (cTnI) using an aptamer sandwich assay immobilized on the device surface. Overall, the optical waveguides integrated with SERS show a miniaturized sensing platform for the detection of small molecules and large proteins, potentially enabling multiplexed detection for clinically relevant applications.

Highly sensitive SERS-based lateral flow immunoassay of fipronil using bimetallic Au@Ag@Ag nanorods.

Abimetallic core-shell-shell nanorods structure with gap-embedded Raman reporter 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB) was developed and applied as a SERS-active nanotag in surface-enhanced Raman scatteringlateral flow immunoassay (SERS-LFIA) of theinsecticide fipronil. Due to the strong SERS signal of the AuDTNB@AgDTNB@AgNRods, fipronil is detected with extremely low detection limit of 4.6pg/mL. To the best of our knowledge, the proposed technique is the first SERS-LFIA of fipronil, proven to be effective in the selective determination of the target analyte and capable of detecting fipronil in a matrix of food samples (cucumber and apple juice) with recoveries of 97.0-117.0%. Moreover, the applied functionalization of the SERS nanotag with anti-species antibodies has provided a versatile immunoprobe that could improve performance of different LFIAs.

Targeting Candida albicans O-acetyl-L-homoserine sulfhydrylase (Met15p) in antifungal treatment

Fungal infections are a serious threat to public health as they are becoming increasingly frequent. A major problem stems also from a rising fungal resistance to currently available antifungal therapies, therefore novel molecular targets are highly desirable. Exploration of enzymes participating in the biosynthesis pathways of essential amino acids such as L-methionine (L-Met) may provide new insights into pharmaceutical development. The MET15 gene from Candida albicans, encoding O-acetyl-L-homoserine sulfhydrylase (Met15p), an enzyme catalyzing the second step in that pathway, was cloned and expressed in two versions: as N and C-terminal oligo-His-tagged fusion proteins. The recombinant enzymes revealed appropriate activity, and catalyzed conversion of O-acetyl-L-homoserine and a sulfide ion to produce L-homocysteine. A new RP-HPLC-DAD method, using the enzymatic reaction product pre-column derivatization with 5,5’-dithio-bis-(2-nitrobenzoic acid) was developed and used by us to determine Met15p activity. Newly synthesized compounds as well as two commercially available exhibited a Met15p inhibitory effect which was related to antifungal activity. Fungal cells’ sensitivity to inhibitors depending on the presence or absence of L-Met in the medium clearly indicated Met15p targeting. Moreover, the synergistic effect of the first methionine biosynthetic enzyme affecting inhibitor and Met15p inhibitors indicate that methionine biosynthesis pathway enzymes are promising molecular targets.

An efficient and practical synthesis of ferroptosis inducer erastin

Erastin, a classic ferroptosis inducer, mediates ferroptosis through various molecular pathways. A highly efficient and convenient synthesis of erastin has been developed, starting from 2-nitrobenzoic acid through 7 steps in an overall yield of 21.6%. This synthesis approach features the efficient construction of the key quinazolinone core and highly selective bromination.

Degradation of P-Nitrobenzoic Acid and 4-Chlorobenzoic Acid by Catalytic Ozonation with Modified Birnessite-Type MnO2 as Catalyst

Degradation of P-Nitrobenzoic Acid and 4-Chlorobenzoic Acid by Catalytic Ozonation with Modified Birnessite-Type MnO2 as Catalyst

Silver shelled gold nanorods for sensitive detection of cholesterol and triglycerides

We report the synthesis of bimetallic plasmonic nanostructure of silver shelled gold nanorods (Ag–Au NRs), subsequently employed for the selective detection of cholesterol (Cho) and triglycerides (TGl) utilizing Surface Enhanced Raman Spectroscopy (SERS). In this direction, the gold nanorods (Au NRs) were synthesized via seed mediated growth method followed by forming a silver shell with reduction of AgNO3 onto Au NRs. Ag–Au NRs showed significantly augmented SERS property owing to hybridization of Localized Surface Plasmon Resonances (LSPR) of silver and gold. The enhanced plasmonic property was thus employed for biosensing. For this, two different Raman reporter molecules, 5,5′–dithiobis–(2–nitrobenzoic acid) (DTNB) and 4–aminothiophenol (4ATP) were immobilized separately on Ag–Au NRs to synthesize SERS active nanoprobes, before the attachment of the bioreceptors – cholesterol oxidase (ChOx) and lipase (Lp) to form ChOx–DTNB–Ag–Au NRs and Lp–4ATP–Ag–Au NRs. These nanoprobes were then utilized for the quantification of Cho and TGl via liquid mode Raman spectroscopic study. The change in SERS spectral intensity of DTNB and 4ATP were systematically recorded in reference to the baseline sample to mark the calibration for both Cho and TGl. Additionally, interference studies considering effects of ascorbic acid, glucose, sodium and potassium ion were performed to unveil excellent selectivity of the proposed method.

Novel Strategy of Treating 2-Nitrobenzoic Acid Crystals with Energetic N2 Neutrals Using Cold Plasma

The organic adduct compounds of 2-nitrobenzoic acid crystals were grown as optically transparent crystals using the conventional slow evaporation solution technique. The crystals were powdered and irradiated with cold plasma. Cell parameter analysis confirmed the formation of a new crystalline material that resides in the triclinic P crystal system with space group P1. Fourier transform infrared spectra were recorded using the KBr pellet technique to determine the vibrational functional groups in the compound. Powder X-ray diffraction analysis was used to reveal the crystalline orientation of the powdered samples of the grown crystals. The obtained full width at half maximum for the (001) plane in the XRD spectrum indicates the excellent crystalline quality of the 2-nitrobenzoic acid crystals. The recorded UV–Vis absorption spectra reveal that the grown powdered crystal samples possess cut-off edges wavelengths at 428 and 428 nm and 353 and 354 nm for pure and plasma-treated samples, respectively. The optical energy bandgaps were found to be 2.0, 2.25, 4.06, and 4.02 eV for the pure and plasma-treated samples, respectively. The photoluminescence spectra show the blue emissions of the crystal. The FE-SEM images show the morphological modifications in which rounded platelets appear on the surfaces of the treated crystals.

Electron paramagnetic resonance study of the paramagnetic centers in gamma-irradiated 2-nitrobenzoic acid single crystal

2-nitrobenzoic acid (C7H5NO4) (2NBA) single crystals were made paramagnetic using 60Co-gamma rays. An attempt was made to detect the resonance form formed in 2-nitrobenzoic acid single crystal with Electron Paramagnetic Resonance (EPR) Spectroscopy. EPR spectra were taken at 125 K in three different axes of the crystal. As a result of EPR analysis of gamma irradiated 2NBA single crystal, it was understood that 2NBA anion radical was formed. The principal values of the hyperfine structure constants, the principal values of the g-tensor and their direction cosines were calculated.

Rapid and effective protocol to measure glutathione peroxidase activity

Abstract Background Intracellular hydroperoxides are harmful reactive oxygen species that can cause damage. Cells depend on antioxidant enzymes such as glutathione peroxidase (GPx) to prevent their accumulation. GPx is present in all cell compartments, including the cytosol, mitochondria, and peroxisomes. This article will present a rapid and reliable method for measuring GPx activity, which has been rigorously tested and proven dependable. Results The enzyme samples are incubated in a phosphate buffer containing specific concentrations of glutathione (GSH) and peroxide and then incubated for a suitable time to react before Ellman's reagent (5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) is added. This method, designed for ease of use, is effective and straightforward. When GSH reacts with DTNB, mixed disulfides (GS-S-DTNB) are formed, where the thiol group replaces one of the nitrobenzoic acid moieties in DTNB. The release of the nitrobenzoic acid group as nitro-2-thiobenzoate anion (TNB−) creates a yellow anion that can be measured spectrophotometrically at a wavelength of 412 nm. The intensity of the yellow color is directly proportional to the unreacted glutathione concentration. GPx activity was linked to decreased absorbance of the TNB− anion, providing a sensitive and relatively specific method for detecting thiol groups in various biological samples. Conclusion This study utilized a Box–Behnken design (BBD) to apply to response surface modeling (RSM) to determine the best conditions for measuring GPx activity. The efficiency of the new protocol was validated by comparing GPx activity in matched samples using the Bland–Altman plot analysis and reference methods. The new protocol was just as accurate as the reference one, with a correlation coefficient of 0.9991. Graphical abstract

Responsive Supramolecular Nanomicelles Formed through Self-Assembly of Acyclic Cucurbit[n]uril for Targeted Drug Delivery to Cancer Cells.

The supramolecular drug delivery systems (SDDSs) based on host-guest recognition through noncovalent interactions, capable of responsive behavior and dynamic switching to external stimuli, have attracted considerable attention in cancer therapy. In this study, a targeted dual-functional drug delivery system was designed and synthesized. A hydrophilic macrocyclic host molecule (acyclic cucurbit[n]uril ACB) was modified with folic acid (FA) as a targeting ligand. The guest molecule consists of a disulfide bond attached to adamantane (DA) and cannabidiol (CBD) at both ends of the response element of glutathione. Recognition and self-assembly of host and guest molecules successfully functionalize supramolecular nanomicelles (SNMs), targeting cancer cells and releasing drugs in a high glutathione environment. The interactions between host and guest molecules were investigated by using nuclear magnetic resonance (NMR), fluorescence titration, Fourier-transform infrared spectroscopy (FT-IR), and thermal analysis (TGA). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirmed the nanostructure of the SNMs. Experimentation with 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) demonstrated the responsiveness of SNMs to glutathione (GSH). In vitro cytotoxicity assays demonstrated that SNMs had a greater targeting efficacy for four types of cancer cells (HeLa, HCT-116, A549, and HepG2) compared to normal 293T cells. Cellular uptake studies revealed that HeLa cells more readily absorbed SNMs, leading to their accumulation in the tumor cell cytoplasm. Fluorescence colocalization assays verified that SNMs efficiently accumulated in organelles related to energy metabolism and signaling, including mitochondria and the endoplasmic reticulum, affecting cellular metabolic death. Both flow cytometry and confocal nuclear staining assays confirmed that SNMs effectively induced apoptosis over time, ultimately resulting in the death of cancer cells. These findings demonstrate that SNMs exhibit excellent targeting ability, responsiveness, high bioavailability, and stability, suggesting significant potential in drug delivery applications.

Slow magnetic relaxation in rare μ2[sbnd]O-Bridged Holmium(III) and Erbium(III) chain compounds

Lanthanide chain compounds with slow relaxation of the magnetization (SRM) behavior have garnered wide attention due to their rich physical phenomena and wide applications. However, the study with non-Dy3+ ions are still rare, mainly due to the challenges in balancing single-ion magnetic anisotropy and intrachain exchange couplings. In this work, two new μ2O-bridged homospin chain compounds: [Ln(L)2(phen)(μ2OH)(μ2H2O)]n (Ln = Ho(1), Er(2), HL = 4-nitrobenzoic acid, phen = 1,10-phenanthroline), were synthesized under solvothermal conditions and fully characterized. Both compounds exhibit weak but effective intrachain couplings transmitted by single-O bridges, leading to Ising-like chain behavior. Dynamic magnetic measurements within the temperature range revealing this special chain behavior indicate that both compounds also exhibit SRM behavior. Such results suggest they could be categorized to the family of single-chain magnets, which are rarely reported for lanthanide compounds with non-radical ligands and non-Dy3+ systems.

Antimicrobial activities of modified and unmodified pectin obtained from peels of Irvingia gabonensis, Cola milleni, and Theobroma cacao on specific pathogenic organisms

The antibacterial and antifungal activities of ethanolic extracts of pectin derived from the peels of Theobroma cacao, Cola milleni, and Irvingia gabonensis were investigated against phytopathogenic bacteria and fungi. The agar diffusion method was employed to test the extracts against Staphylococus aureus, Pseudomonas aeroginosa, Chromobacterium violaceum, Streptococcus feacalis, Xanthomonas axonopodis, Erwinia carotovora, Sclerotium rulfsii, Pythophthora palmivora, and Pyricularia oryzae. Significant differences (p<0.05) were observed in all control groups. The extracts inoculated with Streptomycin exhibited the highest activity against all bacterial strains. Conversely, the unmodified extracts of pectin samples from cola, cocoa, and wild mango displayed the least inhibitory activity against the tested bacterial strains, while the modified extracts with Chloro Acetic Acid (CAA), Para Amino Benzoic Acid (PABA), and Para Nitro Benzoic Acid (PNBA) showed varying inhibitory effects. The control sample inoculated with Mancozeb demonstrated the highest zone of inhibition against all fungal strains in the three pectin samples. However, the modified pectin samples exhibited increased inhibitory effects compared to the unmodified pectin extract, although the results were closer to the control. The higher values of modified pectin can be attributed to the presence of modifying agents such as long-chain hydrocarbons, acetic acid, chloro compounds, carboxyl, benzene rings, amino groups, and nitro groups. The presence of secondary metabolites in the pectin samples may also contribute to the higher values observed in both modified and unmodified samples. Overall, the results indicate the fungicidal and bactericidal potential of the extracts against the tested organisms, suggesting their potential use as broad-spectrum antimicrobial agents.

Highly Selective Electrosynthesis of 1H-1-Hydroxyquinol-4-ones-Synthetic Access to Versatile Natural Antibiotics.

1H-1-Hydroxyquinolin-4-ones represent a broad class of biologically active heterocycles having an exocyclic N,O motif. Electrosynthesis offers direct, highly selective, and sustainable access to 1-hydroxyquinol-4-ones by nitro reduction. A versatile synthetic route starting from easily accessible 2-nitrobenzoic acids was established. The broad applicability of this protocol was demonstrated on 26 examples with up to 93% yield, highlighted by the naturally occurring antibiotics Aurachin C and HQNO. The practicability and technical relevance were underlined by multigram scale electrolysis.

Ellman's Assay on the Surface: Thiol Quantification of Human Cofilin-1 Protein through Surface Plasmon Resonance.

Oxidative stress on cysteine (Cys)-containing proteins has been associated with physiological disorders, as suggested for the human cofilin-1 (CFL-1) protein, in which the oxidized residues are likely implicated in the aggregation process of α-synuclein, leading to severe neuronal injuries. Considering the relevance of the oxidation state of cysteine, quantification of thiols may offer a guide for the development of effective therapies. This work presents, for the very first time, thiol quantification within CFL-1 in solution and on the surface following classic and adapted versions of Ellman's assay. The 1:1 stoichiometric Ellman's reaction occurs between 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB), and the free thiol of the cysteine residue, producing two 2-nitro-5-thiobenzoate (TNB2-) ions, one of which is released into the medium. While in solution, the thiol concentration was determined by the absorbance of the released TNB2-, on the surface, the mass of the attached TNB2- ion to the protein allowed the quantification by means of the multiparametric surface plasmon resonance (MP-SPR) technique. The SPR angle change after the interaction of DTNB with immobilized CFL-1 gave a surface coverage of 26.5 pmol cm-2 for the TNB2- ions (ΓTNB2-). The ratio of this value to the surface coverage of CFL-1, ΓCFL-1 = 6.5 ± 0.6 pmol cm-2 (also determined by MP-SPR), gave 4.1 as expected for this protein, i.e., CFL-1 contains four Cys residues in its native form (reduced state). A control experiment with adsorbed oxidized protein showed no SPR angle change, thus proving the reliability of adapting Ellman's assay to the surface using the MP-SPR technique. The results presented in this work provide evidence of the heterogenization of Ellman's assay, offering a novel perspective for studying thiol-containing species within proteins. This may be particularly useful to ensure further studies on drug-like molecules that can be carried out with validated oxidized or reduced CFL-1 or other analogous systems.

Rapid detection of African swine fever virus via SERS probe-modified sandwich hybridization assay.

Rapid and reliable detection method for African swine fever virus (ASFV) is proposed by surface-enhanced Raman spectroscopy (SERS). The ASFV target DNA can be specifically captured by sandwich hybridization between nanomagnetic beads and a SERS probe. Experimental results show that the significant Raman signal of the SERS probe with gold nanoparticles and a molecular reporter DTNB (5,5'-dimercapto-bis (2-nitrobenzoic acid)) can be adopted for detecting the hybridization chain reaction of ASFV DNA. The advantage of the SERS sandwich hybridization assay is the large response range from the single molecule level to 108 copies per mL, which not only can overcome the tedious timerequired for theamplification reaction but also provides a comparative method to polymerase chain reaction. Furthermore, real samples of African swine fever virus were detected from different subjects of swine fever virus including porcine reproductive respiratory syndrome virus and Japanese encephalitis virus. The proposed biosensor method can rapidly detect ASFV correctly within 15min as a simple, convenient, low-cost detection approach. The biosensor can be used as a platform for the determination in biological, food, and environmental analytical fields.

A dual-mode immunochromatographic sensor with photothermal and surface-enhanced Raman scattering for sensitive detection of aflatoxin B1

Multimodal lateral flow immunoassay has displayed the great potential to improve the flexibility and practicality of point-of-care testing. Herein, this study developed a dual-mode photothermal (PT) and surface-enhanced Raman scattering (SERS) immunochromatographic sensor for sensitive detection of aflatoxin B1 (AFB1). The bifunctional waxberry-like core-satellite nanoparticles loaded with 5,5′-Dithiobis (2-nitrobenzoic acid) (DTNB) were prepared and coupled with antibody to form PT@SERS nanoprobes for qualitative and quantitative detection of AFB1. The photothermal conversion efficiency and SERS enhancement factor of the nanoprobes were 42.11 % and 1.59 × 107, respectively. Under the optimal conditions, the limit of detection of PT assay was 0.033 ng/mL with a linear range of 0.05–10 ng/mL (R2 = 0.997); the limit of detection of SERS assay was 0.0073 ng/mL with a linear range of 0.005–10 ng/mL (R2 = 0.998). The results of the specificity analysis indicated no cross-reactions with the other toxins. The recoveries of the spiked corn and peanut were from 85.39 % to 112.15 % (PT assay) and 80.04 % to 106.57 % (SERS assay), respectively. The assay demonstrated that the developed dual-mode sensor provided a promising option for achieving the rapid detection of AFB1.

Ice crystals and oxidative stress affect the viability of Areca catechu seeds following cryopreservation

This study aimed to examine the effects of ice crystals and oxidative stress on seed viability in the context of cryopreservation, with the ultimate goal of identifying potential solutions to address the persistently low regeneration rate observed in recalcitrant medicinal plant seeds following cryopreservation. Using differential scanning calorimetry technology alongside seeds germination at different moisture levels after cryopreservation helped determine the best moisture content and freezing process for Areca catechu seeds. Seeds with 17–21 % moisture content and treated with PVS2 vitrification solution showed higher survival rates after cryopreservation. The oxidative markers of A. catechu seed embryos exhibited alterations due to vitrification freezing. However, there was no substantial association between seed viability and oxidative markers, such as reactive oxygen species (ROS), suggesting that oxidative damage mediated by ROS is not the primary factor contributing to the diminished viability of A. catechu seeds following cryopreservation. The inclusion of vitamin E, reduced glutathione (GSH), and 2-nitrobenzoic acid in the vitrification cryoprotectant achieved some improvement in seed viability of approximately 10 times, with GSH exhibiting the most pronounced optimizing effect.

Ceria nanocatalyst-supported oxidative organic transformations of aromatic alcohols and p-nitrotoluene

Hydrothermally derived nanocubes of CeO2(10 nm) were explored as an efficient heterogeneous catalyst in the partial oxidation of aromatic alcohols to the corresponding aldehydes and aerobic oxidation ofp-nitrotoluene top-nitrobenzoic acid. The CeO2nanocatalyst was characterized by x-ray diffraction, transmission electron microscopy (TEM), energy dispersive spectroscopy, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared spectroscopy, thermal gravimetric analysis and ultraviolet-visible spectroscopy. TEM/high-resolution TEM micrographs reveal a morphology of mostly cubic nanostructures with exposed highly active {100} and {110} facets. The surface area of nanoceria was determined by BET analysis and found to be 33.8 m2g-1. To demonstrate the universality of the catalytic system, the selective oxidation of different substrates of benzylic alcohol and complete oxidation ofp-nitrotoluene was investigated under mild conditions. Absolute selectivity towards their respective aldehydes was found to be 99.50% (benzaldehyde), 90.18% (p-chlorobenzaldehyde), 99.71% (p-nitrobenzaldehyde), 98.10% (p-fluorobenzaldehyde), 94.66% (p-anisaldehyde) and 86.14% (cinnamaldehyde). Moreover, the catalytic oxidative transformation of nitrotoluene results in 100% conversion with 99.29% selectivity towards nitrobenzoic acid.

Exploring the Chemistry, Reactions, Applications, and Biomedical Potentials of 2-Nitrobenzaldehyde and 2-Chlorobenzaldehyde

This article investigates the diverse chemical reactions and applications of 2-nitrobenzaldehyde, exploring its versatility in synthetic organic chemistry. The focus is on key reactions such as reduction to yield 2-aminobenzaldehyde, Schiff base synthesis with primary amines, Michael addition reactions, Sandmeyer reaction for the formation of 2-nitrobenzoic acid, selenium dioxide oxidation to 2-nitrobenzoic acid, and condensation reactions leading to benzanthrone derivatives. Each reaction pathway is discussed along with its potential applications in various fields. The second part of the review shifts the spotlight to 2-chlorobenzaldehyde, emphasizing its physical and chemical properties. Further exploration of 2-chlorobenzaldehyde's chemical reactivity reveals its engagement in nucleophilic addition reactions, alcoholysis reactions, acetylation reactions, reductive amination reactions, Witting reactions, and halogenation reactions. These reactions showcase the compound's adaptability and utility in diverse synthetic pathways. This article also discusses the biomedical application of 2-chlorobenzaldehyde and 2-nitrobezaldehyde.

Multifunctional Lanthanide Metal-Organic Frameworks Are Used for Fluorescence Sensing of Bi3+, HPO42-, Flu, and PNBA and Application.

Using a nitrogen-containing tricarboxylic acid ligand (imidazole-1-yl) benzene-2,4,6-tricarboxylic acid (H3ttc) and lanthanide metal elements (Dy, Eu, Nd, and Gd), four lanthanide metal organic frameworks (Ln-MOFs) with the same structure, namely, {[Dy2 (Httc)3]·1.5DMF}n(1), {[Eu2 (Httc)3]·1.5DMF}n(2), {[Nd2 (Httc)3]·1.5DMF}n(3), and {[Gd2 (Httc)3]·1.5DMF}n(4), were synthesized under solvothermal conditions. The characterization analysis showed that the four isomorphic Ln-MOFs were trigonal crystals of the R3̅c space group, with good phase purity and thermal stability. Fluorescence analysis showed that complex 1 can be an excellent fluorescence sensor for Bi3+, HPO42-, and fluridine (Flu), while complex 2 can be an excellent fluorescence sensor for p-nitrobenzoic acid (PNBA). And their sensing mechanisms were discussed in detail. The fluorescent test paper and fluorescent seal were prepared by using the excellent luminescence properties of 1 and 2, and the pesticide on the surface of cherry tomato was detected. The applicability of these MOFs as fluorescence sensors was proved. Therefore, Ln-MOFs are expected to have unpredictable application prospects in the field of environmental detection.