Gallic acid-functionalized silver nanoparticles as colorimetric and spectrophotometric probe for detection of Al3+ in aqueous medium

Sensitive and specific detection of trace Al3+ ions using an upconversion nanoparticle-xylenol orange complex via the inner filter effect

We have developed a novel fluorescence sensor based on upconversion nanoparticles (UCNPs) for the rapid and sensitive detection of trace aluminum ions (Al3+). The sensor utilizes the inner filter effect (IFE) between the UCNPs and the xylenol orange-aluminum complex (XO-Al3+), resulting in significant fluorescence quenching at 543 nm upon Al3+ binding. This quenching correlates directly with the Al3+ concentration, allowing for quantitative detection within a range of 0-30 μM and achieving an ultra-low detection limit of 0.19 μM. Selectivity of the sensor is enhanced by the incorporation of ascorbic acid, which masks interfering Fe3+ ions, thus ensuring accurate determination of Al3+ even in the presence of other metal ions. The UCNPs-XO sensor exhibits excellent stability and reproducibility, and minimal interference from commonly co-existing substances. This makes it suitable for the detection of Al3+ in various matrices, including food products and environmental water samples. Our work offers a significant advancement in Al3+ detection, with potential applications in food safety, environmental monitoring, and public health.

Synthesis of F127-GA@ZnO nanogel as a cisplatin drug delivery pH-sensitive system

In this study, a novel drug delivery system based on zinc oxide nanoparticles (ZnO NPs) was developed for the enhanced delivery of cisplatin (CPT) to improve cancer treatment. The ZnO NPs were synthesized from guava leaf extract and then surface-functionalized with gallic acid (GA) to improve their biocompatibility and drug loading capacity. Pluronic F127, a biocompatible polymer, was then conjugated to the GA-modified ZnO NPs to further enhance their stability and cellular uptake. The resulting NPs were characterized by various techniques, including FT-IR, UV-Vis, SEM, TEM, 1H NMR, and DLS. The drug loading and release profiles of CPT from the NPs were investigated, showing high CPT loading capacity and pH-dependent release behavior. The in vitro cytotoxicity of the NPs was evaluated against various cancer cell lines, demonstrating enhanced cytotoxicity compared to free CPT. Overall, this study highlights the potential of GA and Pluronic-modified ZnO NPs as a promising drug delivery system for enhanced CPT delivery and improved cancer therapy.

Silver-loaded poly(vinyl alcohol)/polycaprolactone polymer scaffold as a biocompatible antibacterial system

A chronic nonhealing wound poses a significant risk for infection and subsequent health complications, potentially endangering the patient's well-being. Therefore, effective wound dressings must meet several crucial criteria, including: (1) eliminating bacterial pathogen growth within the wound, (2) forming a barrier against airborne microbes, (3) promoting cell proliferation, (4) facilitating tissue repair. In this study, we synthesized 8 ± 3 nm Ag NP with maleic acid and incorporated them into an electrospun polycaprolactone (PCL) matrix with 1.6 and 3.4 µm fiber sizes. The Ag NPs were anchored to the matrix via electrospraying water-soluble poly(vinyl) alcohol (PVA), reducing the average sphere size from 750 to 610 nm in the presence of Ag NPs. Increasing the electrospraying time of Ag NP-treated PVA spheres demonstrated a more pronounced antibacterial effect. The resultant silver-based material exhibited 100% inhibition of gram-negative Escherichia coli and gram-positive Staphylococcus aureus growth within 6 h while showing non-cytotoxic effects on the Vero cell line. We mainly discuss the preparation method aspects of the membrane, its antibacterial properties, and cytotoxicity, suggesting that combining these processes holds promise for various medical applications.

"AND"-Logic gate-based colorimetric detection of thiocyanate in milk samples using AgNP-EBF as plasmonic nano sensor

At present, the uses of food additives globally are much of a concern due to their after effects upon consumption in higher proportions. Although different sensing strategies are available for their detection, a need for simple, rapid and cost-effective strategy is much of a concern. Herein, we developed a plasmonic nano sensor i.e., AgNP-EBF which was considered as the transducer component for the AND logic gate-based system with Cu²⁺ and thiocyanate as inputs. Optimization and detection of thiocyanates were performed through UV-visible colorimetric sensing procedures where the logic gate allowed the detection of thiocyanate in the range of 100 nM-1 µM with LOD of 53.60 nM within 5-10 min. The proposed system showed high selectivity towards the detection of thiocyanate rather than other interferences. To check the credibility of the proposed system, the logic gate was applied for detection of thiocyanates in real milk samples.

On Recent Developments in Biosynthesis and Application of Au and Ag Nanoparticles from Biological Systems

Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) are extensively studied nanoparticles (NPs) and are known to have profound applications in medicine. The researcher made continuous efforts for the environmental-friendly and economical methods, such as biogenic methods known as green synthesis. There are many strategies for separating and applying gold (Au) and silver (Ag) nanoparticles, of which biological routes have emerged as efficient, low-cost, and environmentally friendly techniques. This review focuses on recent developments of green synthesized AuNPs and AgNPs using biogenic sources such as algae, animals, plants, microbes, bacteria, fungi, and so on. Hence, it discusses their numerous biomedical applications and separating Au and Ag nanoparticles from plants, bacteria, fungi, and algae.

Smartphone-based microfluidic chip modified using pyrrolidine-1-dithiocarboxylic acid for simultaneous colorimetric determination of Cr3+ and Al3+ ions

A portable µ-chip-based colorimetric device was developed for the determination of Cr³⁺ and Al³⁺ ions. The silver nanoparticles were modified with pyrrolidine-1-dithiocarboxylic acid ammonium salt as a novel ligand for the first time. The color of modified AgNPs in the test zone immediately changes after the addition of Cr³⁺ and Al³⁺ ions. The resulting color changes were detected by the naked eye or were taken by a smartphone camera. The obtained images were analyzed by RGB software to assay the Cr³⁺ and Al³⁺ ions concentration. Under optimized experimental conditions, the linear ranges are 0.1-220 and 0.01-250 µM for Cr³⁺ and Al³⁺ ions, respectively. The probe has a limit of detections of 10.66 and 3.55 nM for Cr³⁺ and Al³⁺ in an aqueous solution. In the case of µ-chip, the concentration ranges are 0.1-200 μM and 0.01-220 μM for Cr³⁺ and Al³⁺ ions, with detection limits of 9.18 and 2.30 nM, respectively. The µ-chip showed great potential as a fast detection tool for the monitoring of Cr³⁺ and Al³⁺ ions in real samples such as river water samples.

The Effects of Nature-Inspired Synthesis on Silver Nanoparticle Generation

A wide range of methods can be used for nature-inspired metallic nanoparticle (NP) synthesis. These syntheses, however, are ongoing in the presence of diverse mixtures of different chemical compounds, and all or only a few of these contribute to resultant particle properties. Herein, the linden (Tilia sp.) inflorescence leachate and pure citric and protocatechuic acids were chosen for Ag-AgCl nanoparticle (NP) synthesis, and the resultant particles were then compared. We focused on the following four issues: (1) preparation of Ag-AgCl NPs using the Tilia sp.-based phytosynthetic protocol, (2) analytical determination of the common phenolic, nonphenolic, and inorganic profiles of three Tilia sp. types from different harvesting locations, (3) preparation of Ag-AgCl NPs using a mixture of citric and protocatechuic acids based on chromatographic evaluation, and (4) comparison of Tilia-based and organic acid-based syntheses. Our research confirms that the Tilia organic and inorganic profiles in biomasses are influenced by the harvesting location, and the three sites influenced both the morphology and final NP size. Our processing method was uniform, and this enabled great Ag-AgCl NP reproducibility for each specific biomass. We were then able to prove that the simplified organic acid-based synthesis produced even smaller NPs than Tilia-based synthesis. These findings provide better understanding of the significant influence on NP final properties resulting from other organic acids contained in the linden.

Dual colorimetric sensing of ascorbic acid and thyroxine using Ag-EGCG-CTAB via a DFT approach

In this work, a colorimetric approach for the detection of ascorbic acid (AA) and thyroxine (TH) was developed by synthesizing cost-effective silver nanoparticles (AgNPs) decorated with epigallocatechin gallate (EGCG) and CTAB. EGCG is the major bioactive chemical constituent that played a significant role in this study. The environment around the nanoparticle (NP) was controlled by adding CTAB surfactants. The synthesized NPs were characterized by different advanced techniques including XRD, XPS, SEM, and TEM. UV-visible spectra were thoroughly analyzed for sensing of AA and TH and the colour change of the solution can be visually monitored. The change in the localized surface plasmon resonance (LSPR) properties was used as an asset for the detection of AA and TH. A good linear relationship was obtained in both the sensing schemes with a limit of detection (LoD) of 0.67 μM and 0.33 μM for AA and TH respectively. Furthermore, the nanoparticles (NP) were implemented for real-sample analysis (pharmaceutical tablets). A cost-effective filter paper strip-based method coupled with smartphone scanning sensing was developed for the detection of AA. The interaction of AA and TH with the probe was depicted by a density functional theory (DFT) analysis. The synthesized NPs show tremendous selectivity towards AA and TH and excellent potential for practical applications.

Simultaneous detection of aqueous aluminum(III) and chromium(III) using Persea americana reduced and capped silver nanoparticles

There is a significant interest to develop sensing devices that detect water toxins, especially heavy metal ions. Although there have already been numerical reports on detecting toxic heavy metal ions, the use of adaptable devices could enable a broader range of sensing applications. Here, we used fresh peel extract (PeA) and dried peel extract (DPeA) of Persea americana (Avocado) as a reducing and capping agent to synthesize and stabilize AgNPs. The dimensions of NPs were controlled by tuning pH, temperature, and volume of the reducing agent. The sensitivity and selectivity of the AgNPs toward various metal ions viz. Ni(II), Cd(II), Al(III), Hg(II), Cr(III), Ba(II), Pb(II), Zn(II), Co(II), Mn(II), Cu(II), Ca(II), Mg(II), and K(I) were studied. The detection probe was found to be selective and sensitive toward Al(III) and Cr(III) ions with the detection limit of 0.04 ppm and 0.05 ppm, respectively. High-resolution transmission electron microscope (HRTEM), ultraviolet-visible (UV-Vis) spectroscopy, and dynamic light scattering (DLS) analysis results confirm an agglomeration-based mechanism for sensing both metal ions. This method can be exploited for the colorimetric detection of toxic heavy metals in real water samples.

Au@Ag Core@Shell Nanoparticles Synthesized with Rumex hymenosepalus as Antimicrobial Agent

In this work, we used a sequential method of synthesis for gold-silver bimetallic nanoparticles with core@shell structure (Au@AgNPs). Rumex hymenosepalus root extract (Rh), which presents high content in catechins and stilbenes, was used as reductor agent in nanoparticles synthesis. Size distribution obtained by Transmission Electron Microscopy (TEM) gives a mean diameter of 36 ± 11 nm for Au@AgNPs, 24 ± 4 nm for gold nanoparticles (AuNPs), and 13 ± 3 nm for silver nanoparticles (AgNPs). The geometrical shapes of NPs were principally quasi-spherical. The thickness of the silver shell over AuNPs is around 6 nm and covered by active biomolecules onto the surface. Nanoparticles characterization included high angle annular dark field images (HAADF) recorded with a scanning transmission electron microscope (STEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), UV-Vis Spectroscopy, Zeta Potential, and Dynamic Light Scattering (DLS). Fourier Transform Infrared Spectrometer (FTIR), and X-ray Photoelectron Spectroscopy (XPS) show that nanoparticles are stabilized by extract molecules. A growth kinetics study was performed using the Gompertz model for microorganisms exposed to nanomaterials. The results indicate that AgNPs and Au@AgNPs affect the lag phase and growth rate of Escherichia coli and Candida albicans in a dose-dependent manner, with a better response for Au@AgNPs.

Exploiting Fruit Waste Grape Pomace for Silver Nanoparticles Synthesis, Assessing Their Antioxidant, Antidiabetic Potential and Antibacterial Activity Against Human Pathogens: A Novel Approach

Grape pomace, a most abundant and renewable wine industry waste product was utilized as a suitable reducing, capping, and stabilizing biomolecules for green synthesis of silver nanoparticles (AgNPs). The physicochemical properties of biosynthesized grape pomace extract (GPE)-AgNPs were duly appraised via UV-Visible spectroscopy, X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy. The analytical studies revealed that the GPE-AgNPs were well formed and stable in nature. The functional groups of organic molecules of GPE are present on the surface of AgNPs with average NPs diameter in the range of 20-35 nm. GPE-AgNPs exhibited significant free radical scavenging activity mainly DPPH radical (IC₅₀, 50.0 ± 2.25 μg/mL) and ABTS radical (IC₅₀, 38.46 ± 1.14 μg/mL). Additionally, the synthesized AgNPs showed noticeable inhibition of carbohydrate hydrolyzing enzymes mainly, α-amylase (IC₅₀, 60.2 ± 2.15 μg/mL) and α-glucosidase (IC₅₀, 62.5 ± 2.75 μg/mL). The GPE fabricated AgNPs showed noteworthy antibacterial potential against infectious bacteria viz., Escherichia coli and Staphylococcus aureus. The reaction mechanism of antibacterial activity was studied by measuring the bacterial cell membrane breakage and cytoplasmic contents, mainly, nucleic acid, proteins, and reducing sugar. Therefore, this research attempt illustrated the potential of GPE as a novel source intended for the biosynthesis of AgNPs that may open up new horizons in the field of nanomedicine.