Positively Charged Gold Nanoparticles for Hydrogen Peroxide Detection

One-Pot Synthesis of Tannic Acid-Au Nanoparticles for the Colorimetric Determination of Hydrogen Peroxide and Glucose

This study introduces a novel one-pot method employing tannic acid (TA) to synthesize stable gold nanoparticles (TA-AuNPs), which are characterized using transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. We apply these TA-AuNPs in a newly developed colorimetric assay for hydrogen peroxide (H2O2) detection that utilizes the oxidation of iodide (I-) on TA-AuNPs, leading to a detectable yellow color change in the solution. The reaction kinetics are captured by the rate equation R = 0.217[KI]0.61[H2O2]0.69. The possible sensing mechanism was proposed through density functional theory calculations. At the optimum conditions, the proposed TA-AuNPs/I- system demonstrated a linear relationship between H2O2 concentration and absorbance intensity (λ = 350 nm) and achieved a limit of detection (LOD) of 7.33 μM. Furthermore, we expand the utility of this approach to glucose detection by integrating glucose oxidase into the system, resulting in a LOD of 10.0 μM. Application of this method to actual urine samples yielded spiked recovery rates ranging from 96.6-102.0% and relative standard deviations between 3.00-8.34%, underscoring its efficacy and potential for real-world bioanalytical challenges.

Application of nanopesticides and its toxicity evaluation through Drosophila model

Insects feed on plants and cause the growth of plants to be restricted. Moreover, the application of traditional pesticides causes harmful effects on non-target organisms and poses serious threats to the environment. The use of conventional pesticides has negative impacts on creatures that are not the intended targets. It also presents significant risks to the surrounding ecosystem. Insects that are exposed to these chemicals eventually develop resistance to them. This review could benefit researcher for future development of nanopesticides research. This is because a holistic approach has been taken to describe the multidimensional properties of nanopesticides, health and environmental concerns and its possible harmful effects on non-target organisms and physiochemical entities. The assessment of effects of the nanopesticides is also being discussed through the drosophotoxicology. The future outlooks have been suggested to take a critical analysis before commercialization or formulation of the nanopesticides.

Spectroscopic/colorimetric dual-mode rapid and ultrasensitive detection of reactive oxygen species based on shape-dependent silver nanostructures

Excessive production of reactive oxygen species (ROS) from endogenous and exogenous pathways is linked to oxidative stress and various diseases. Although a variety of ROS probes have been developed, their multistep synthesis strategies and complicated instrumental operating procedures limit their frequent use. In this work, different shaped silver nanostructures including nanoparticles, nanoprisms, and nanocubes were utilized to demonstrate simple spectroscopic and colorimetric techniques for sensitive ROS detection. The nanostructures displayed different sensing behaviours recorded via plasmon tuning with morphological changes upon exposure to ROS. Among the nanostructures, silver nanocubes were found to be extremely efficient in recognising a particular ROS, namely hypochlorite ions. The detection limits of this ROS were calculated to be 23.76 nM, 85.71 nM, and 36.37 nM for silver nanoparticles, nanoprisms, and nanocubes, respectively. A time-dependent microscopic examination was carried out and revealed that the presence of hypochlorite ions deteriorates structural morphologies. The formation of highly reactive chlorite, chlorate, and chloride ions in hypochlorite ion solution was ascribed to the significant spectroscopic and microscopic changes in all the nanostructures. The attenuation of plasmonic peaks and etching of nanostructures by ROS were supported by the increment of the oxidation state of silver. In addition, silver nanocubes were successfully applied to recognize ROS in Spinacia oleracea and real water samples. The results confirm the potentiality of silver nanostructures for sensitive detection of ROS in biological and environmental systems.

Rapid Surface-Enhanced Raman Spectroscopy Detection of Chlorothalonil in Standard Solution and Orange Peels with Pretreatment of Ultraviolet Irradiation

At present, the detection of chlorothalonil is generally based on chromatography and immunoassay; both of which are time-consuming and costly. In this study, Surface-enhanced Raman Spectroscopy (SERS) has been successfully utilized in the detection of chlorothalonil coupled with photochemistry and meanwhile, gold nanoparticles were prepared to enhance the Raman signal. Two Raman peaks (2246 cm^- 1 and 2140 cm^- 1) of chlorothalonil were appeared after ultraviolet (UV) irradiation compared to the original solution. Chlorothalonil generated excited and weakened C≡N bonds in its structure by absorbing UV energy, thus leading to two kinds of corresponding peaks. These two kinds of peaks were both selected as analytical peaks in chlorothalonil detection. Different light sources and solvents were made different contributions to the final spectra. Chlorothalonil methanol solution under 302 nm wavelength irradiation was performed the best. The 2246 cm^- 1 sharp peak represented to the normal C≡N bond appeared at first, which overall trend was significantly increased followed by a gradual decrease. The 2140 cm^- 1 broad peak represented to the weakened C≡N bond appeared later, which overall trend was increased as the irradiation time passing by and then kept stable. Natural bond orbital (NBO) analysis indicates that the downshift of C≡N bond from 2246 cm^- 1 to 2140 cm^- 1 is due to the increase of electronic populations of π* orbital of C≡N bond transited from π orbital excited by UV irradiation. The positively charged C≡N bond had more chance to approach negatively charged gold nanoparticles. The detection limit of chlorothalonil was as low as 0.1 ppm in the standard solution. Orange peels spiked with chlorothalonil oil were also detected in this paper to confirm the practical operability of this method. The SERS method may be further developed as a rapid detection of pesticides that contains a triple bond by utilizing photochemistry.

Selected nanotechnologies and nanostructures for drug delivery, nanomedicine and cure

The development of nanoparticle-based drugs has provided many opportunities to diagnose, treat and cure challenging diseases. Through the manipulation of size, morphology, surface modification, surface characteristics, and materials used, a variety of nanostructures can be developed into smart systems, encasing therapeutic and imaging agents with stealth properties. These nanostructures can deliver drugs to specific tissues or sites and provide controlled release therapy. This targeted and sustained drug delivery decreases the drug-related toxicity and increases the patient's compliance with less frequent dosing. Nanotechnology employing nanostructures as a tool has provided advances in the diagnostic testing of diseases and cure. This technology has proven beneficial in the treatment of cancer, AIDS, and many other diseases. This review article highlights the recent advances in nanostructures and nanotechnology for drug delivery, nanomedicine and cures.

A functional FePt@MOFs (MIL-101(Fe)) nano-platform for high efficient colorimetric determination of H2O2

Surface-modified FePt nanoparticles were loaded into metal–organic frameworks in a facile in situ way and the resulting material (FePt@MOFs NCs) acted as a high efficient colorimetric detection agent for H₂O₂.

Recent progress of algae and blue-green algae-assisted synthesis of gold nanoparticles for various applications

The hazardous effects of current nanoparticle synthesis methods have steered researchers to focus on the development of newer environmentally friendly and green methods for synthesizing nanoparticles using nontoxic chemicals. The development of environmentally friendly methods of nanoparticle synthesis with different sizes and shapes is one of the pressing challenges for the current nanotechnology. Several novel green approaches for the synthesis of AuNPs have been explored using different natural sources, such as plants, algae, bacteria, and fungi. Among organisms, algae and blue-green algae are of particular interest for nanoparticle synthesis. Gold nanoparticles (AuNPs) have a range of applications in medicine, diagnostics, catalysis, and sensors because of their significant key roles in important fields. AuNPs have attracted a significant interest for use in a variety of applications. The widespread use of AuNPs can be accredited to a combination of optical, physical, and chemical properties as well as the miscellany of size, shape, and surface composition that has been adopted through green synthesis methods.