Nanoparticles In Aqueous Media Research Articles

Solvent‐Induced Flower‐ and Cudgel‐Shaped Porous Organic Polymers: Effective Supports of Palladium Nanoparticles for Dehalogenation in Net Water

AbstractDehalogenation of aromatic halides is one of the most important reactions for detoxification of water ecosystems; at the same time the ability is inevitably tied to the dispersibility of catalyst in aqueous medium. Herein, we present aporous organic polymers containing hydrophilic urea groups (UPOPs) for effective immobilization of palladium nanoparticles (NPs) through a facile urea‐forming condensation reaction. The urea groups not only serve as an intriguing linkage of organic framework, but also endows Pd@UPOPs outstanding dispersibility in H2O. The morphology of UPOPs have exerted important influence upon the size and dispersion of palladium NPs as well as their catalytic performances. The palladium NPs are well dispersed on the surface of UPOP‐1 with an average size of 2.1±0.3 nm. In contrast, palladium NPs on UPOP‐2 exhibit a dual size distribution with an average diameter of 2.0±0.4 and 4.2±0.4 nm. The dehalogenation reactions of chlorobenzene have demonstrated that Pd@UPOP‐1 with flower‐shaped morphology show higher catalytic activity, recyclability and stability than that of Pd@UPOP‐2 with cudgel‐shaped morphology. This work offers/supplies a new insight for the development of efficient catalytic systems based on porous organic polymers supported metal NPs in aqueous medium.

Bioremoval of PVP-coated silver nanoparticles using Aspergillus niger: the role of exopolysaccharides.

Extensive use of engineered nanoparticles has led to their eventual release in the environment. The present work aims to study the removal of Polyvinylpyrrolidone-coated silver nanoparticles (PVP-Ag-NPs) using Aspergillus niger and depict the role of exopolysaccharides in the removal process. Our results show that the majority of PVP-Ag-NPs were attached to fungal pellets. About 74% and 88% of the PVP-Ag-NPs were removed when incubated with A. niger pellets and exopolysaccharide-induced A. niger pellets, respectively. Ionized Ag decreased by 553 and 1290-fold under the same conditions as compared to stock PVP-Ag-NP. PVP-Ag-PVP resulted in an increase in reactive oxygen species (ROS) in 24 h. Results show an increase in PVP-Ag-NPs size from 28.4 to 115.9 nm for A. niger pellets and 160.3 nm after removal by stress-induced A. niger pellets and further increased to 650.1 nm for in vitro EPS removal. The obtained findings show that EPS can be used for nanoparticle removal, by increasing the net size of nanoparticles in aqueous media. This will, in turn, facilitate its removal through conventional filtration techniques commonly used at wastewater treatment plants.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-18018-9.

Preparation, characterization and investigation of the anti-‎human ovarian cancer of silver nanoparticles green-formulated by Salvia officinalis leaf ‎aqueous extract ‎

IntroductionIn the present study, we decided to prepare and formulate a new chemotherapeutic drug (silver nanoparticles in ‎aqueous medium using Salvia officinalis leaf aqueous extract) for the treatment of human ovarian cancer in the in ‎vitro condition.Material and methodsThe organometallic chemistry tests such as Scanning Electron Microscopy (SEM), UV–Visible Spectroscopy ‎‎(UV-Vis), and Fourier Transformed Infrared Spectroscopy (FT‐IR) were used for characterizing of silver ‎nanoparticles. For investigating the antioxidant potentials of AgNO3, Salvia officinalis aqueous extract, and ‎silver nanoparticles, the DPPH test was used in the presence of butylated hydroxytoluene as the positive ‎control. To survey the cytotoxicity and anti-human ovarian cancer activities of AgNO3, Salvia officinalis ‎aqueous extract, and silver nanoparticles, MTT assay was used on the human ovarian cancer cell lines i.e., Caov-‎‎3‎, SK-OV-3, and PA-1‎. ‎ResultsIn UV-Vis, the clear peak in the wavelength of 421 nm indicated the formation of silver nanoparticles. In FT-IR ‎test, the presence of many antioxidant compounds with related bonds caused the excellent condition for ‎reducing of silver in the silver nanoparticles. The silver nanoparticles inhibited half of the DPPH molecules in ‎the concentration of 251 µg/mL. The best result of anti-human ovarian cancer effects of silver nanoparticles ‎against the above cell lines was observed in the case of the SK-OV-3 cell line. ‎ConclusionsSilver nanoparticles had very low cell viability and anti-human ovarian cancer properties dose-dependently ‎against Caov-3‎, SK-OV-3, and PA-1 cell lines without any cytotoxicity on the normal cell line (HUVECs). ‎

Upconverting Nanoparticles in Aqueous Media: Not a Dead-End Road. Avoiding Degradation by Using Hydrophobic Polymer Shells

Upconverting Nanoparticles in Aqueous Media: Not a Dead-End Road. Avoiding Degradation by Using Hydrophobic Polymer Shells

Upconverting Nanoparticles in Aqueous Media: Not a Dead-End Road. Avoiding Degradation by Using Hydrophobic Polymer Shells.

The stunning optical properties of upconverting nanoparticles (UCNPs) have inspired promising biomedical technologies. Nevertheless, their transfer to aqueous media is often accompanied by intense luminescence quenching, partial dissolution by water, and even complete degradation by molecules such as phosphates. Currently, these are major issues hampering the translation of UCNPs to the clinic. In this work, a strategy is developed to coat and protect β-NaYF4 UCNPs against these effects, by growing a hydrophobic polymer shell (HPS) through miniemulsion polymerization of styrene (St), or St and methyl methacrylate mixtures. This allows one to obtain single core@shell UCNPs@HPS with a final diameter of ≈60-70nm. Stability studies reveal that these HPSs serve as a very effective barrier, impeding polar molecules to affect UCNPs optical properties. Even more, it allows UCNPs to withstand aggressive conditions such as high dilutions (5µgmL-1 ), high phosphate concentrations (100mm), and high temperatures (70°C).The physicochemical characterizations prove the potential of HPSs to overcome the current limitations of UCNPs. This strategy, which can be applied to other nanomaterials with similar limitations, paves the way toward more stable and reliable UCNPs with applications in life sciences.

Optical properties of dextran-stabilized silicon nanoparticles in aqueous medium

Silicon nanoparticles (Si-NPs) with initial sizes of the order of 100 nm were prepared by femtosecond laserablation-fragmentation of microcrystalline silicon in water followed by drying and resuspending in wateror in aqueous solutions of dextran. The prepared aqueous suspensions of Si-NPs without dextran and withdextran coating were investigated by means of the scanning electron microscopy, dynamic light scatteringand optical absorption spectroscopy in the spectral range from 250 to 800 nm. The optical absorption ofuncoated Si-NPs in an aqueous medium with different pH-level varied from 4 to 8 was found to decreasewith time because of a process of the dissolution of those NPs in water. The dissolution rate dependednonmonotonically on the solution acidity (pH level) and the corresponding times were in the range from 50to 180 hours. The addition of dextran into the solution was found to significantly decrease the dissolutionrate of Si-NPs to 300 hours because of the coating of NPs with a polymer shell. The obtained results canbe useful to develop new biomedical technologies involving Si-NPs as stabilized theranostics (therapy anddiagnostics) agents. Key words: nanoparticles, dextran, biopolymer, optics, absorbance.

Competitive and multiple adsorption of humic and fulvic acids on spherical silver and gold engineered nanoparticles in aqueous media: A first-principles study

Experimental studies have confirmed that engineered nanoparticles have different shapes such as cylindrical and spherical just to mention a few. The different shapes of engineered nanoparticles are likely to interact with natural organic matter in the aquatic environment. It is evident that when two or more different NOM’s adsorbed on molecules are going to compete for active sites. To understand the competitive and multiple adsorptions of humic acid (HA) and fulvic acid (FA) on spherical silver and gold engineered nanoparticles in aqueous media, dispersion-corrected density functional theory (DFT-D) has been used. For this purpose, HA and FA were used as model compounds for NOM. The results provide evidence of molecular interactions, competition for adsorption sites between NOM’s and Ag and Au spherical engineered nanoparticles, which are critical to understanding engineered nanoparticles behaviour and toxicity in the natural environment. The adsorption energy results of the mixtures of four HA and FA on Ag and Au spherical engineered nanoparticles have the highest adsorption energy of −1.94 eV and −3.40 eV respectively. Global reactivity descriptors such as ionization potential, electron affinity, chemical potential, hardness and electrophilicity index which give insights on adsorption of FA and HA on Ag and Au spherical engineered nanoparticles were calculated.

Highly Efficient Modular Construction of Functional Drug Delivery Platform Based on Amphiphilic Biodegradable Polymers via Click Chemistry.

Amphiphilic copolymers with pendant functional groups in polyester segments are widely used in nanomedicine. These enriched functionalities are designed to form covalent conjugates with payloads or provide additional stabilization effects for encapsulated drugs. A general method is successfully developed for the efficient preparation of functional biodegradable PEG-polyester copolymers via click chemistry. Firstly, in the presence of mPEG as initiator, Sn(Oct)2-catalyzed ring-opening polymerization of the α-alkynyl functionalized lactone with D,L-lactide or ε-caprolactone afforded linear mPEG-polyesters bearing multiple pendant alkynyl groups. Kinetic studies indicated the formation of random copolymers. Through copper-catalyzed azide-alkyne cycloaddition reaction, various small azido molecules with different functionalities to polyester segments are efficiently grafted. The molecular weights, polydispersities and grafting efficiencies of azido molecules of these copolymers were investigated by NMR and GPC. Secondly, it is demonstrated that the resulting amphiphilic functional copolymers with low CMC values could self-assemble to form nanoparticles in aqueous media. In addition, the in vitro degradation study and cytotoxicity assays indicated the excellent biodegradability and low cytotoxicity of these copolymers. This work provides a general approach toward the preparation of functional PEG-polyester copolymers in a quite efficient way, which may further facilitate the application of functional PEG-polyesters as drug delivery materials.

Transformable Helical Self-Assembly for Cancerous Golgi Apparatus Disruption.

Golgi apparatus is a major subcellular organelle responsible for drug resistance. Golgi apparatus-targeted nanomechanical disruption provides an attractive approach for killing cancer cells by multimodal mechanism and avoiding drug resistance. Inspired by the poisonous twisted fibrils in Alzheimer's brain tissue and enhanced rigidity of helical structure in nature, we designed transformable peptide C6RVRRF4KY that can self-assemble into nontoxic nanoparticles in aqueous medium but transformed into left-handed helical fibrils (L-HFs) after targeting and furin cleavage in the Golgi apparatus of cancer cells. The L-HFs can mechanically disrupt the Golgi apparatus membrane, resulting in inhibition of cytokine secretion, collapse of the cellular structure, and eventually death of cancer cells. Repeated stimulation of the cancers by the precursors causes no acquired drug resistance, showing that mechanical disruption of subcellular organelle is an excellent strategy for cancer therapy without drug resistance. This nanomechanical disruption concept should also be applicable to multidrug-resistant bacteria and viruses.

Self-Assembling Antioxidants for Ischemia-Reperfusion Injuries.

Significance: Ischemia-reperfusion (IR) injury is a major component of severe damage in vascular occlusion during stroke, myocardial infarction, surgery, and organ transplantation, and is exacerbated by the excessive generation of reactive oxygen species (ROS), which occurs particularly during reperfusion. With the aging of the population, IR injury is becoming a serious problem in various organs, such as the kidney, brain, and heart, as well as in the mesenteric capillaries. Recent Advances: To prevent reperfusion injuries, natural and synthetic low-molecular-weight (LMW) antioxidants have been well studied. Critical Issues: However, these LMW antioxidants have various problems, including adverse effects due to excessive cellular uptake and their rapid clearance by the kidney, and cannot fully exert their potent antioxidant capacity in vivo. Future Directions: To overcome these problems, we designed and developed redox polymers with antioxidants covalently conjugated with them. These polymers self-assemble into nanoparticles in aqueous media, referred to as redox nanoparticles (RNPs). RNPs suppress their uptake into normal cells, accumulate at inflammation sites, and effectively scavenge ROS in damaged tissues. We had developed two types of RNPs: RNPN, which disintegrates in response to acidic pH; and RNPO, which does not collapse, regardless of the environmental pH. Utilizing the pH-sensitive and -insensitive characteristics of RNPN and RNPO, respectively, RNPs were found to exhibit remarkable therapeutic effects on various oxidative stress disorders, including IR injuries. Thus, RNPs are promising nanomedicines for use as next-generation antioxidants. This review summarizes the therapeutic impacts of RNPs in the treatment of kidney, cerebral, myocardial, and intestinal IR injuries. Antioxid. Redox Signal. 36, 70-80.

Targeted and activatable nanosystem for fluorescent and optoacoustic imaging of immune-mediated inflammatory diseases and therapy via inhibiting NF-κB/NLRP3 pathways

Immune-mediated inflammatory diseases (IMIDs) represent a diverse group of diseases and challenges remain for the current medications. Herein, we present an activatable and targeted nanosystem for detecting and imaging IMIDs foci and treating them through blocking NF-κB/NLRP3 pathways. A ROS-activatable prodrug BH-EGCG is synthesized by coupling a near-infrared chromophore with the NF-κB/NLRP3 inhibitor epigallocatechin-3-gallate (EGCG) through boronate bond which serves as both the fluorescence quencher and ROS-responsive moiety. BH-EGCG molecules readily form stable nanoparticles in aqueous medium, which are then coated with macrophage membrane to ensure the actively-targeting capability toward inflammation sites. Additionally, an antioxidant precursor N-acetylcysteine is co-encapsulated into the coated nanoparticles to afford the nanosystem BH-EGCG&NAC@MM to further improve the anti-inflammatory efficacy. Benefiting from the inflammation-homing effect of the macrophage membrane, the nanosystem delivers payloads (diagnostic probe and therapeutic drugs) to inflammatory lesions more efficiently and releases a chromophore and two drugs upon being triggered by the overexpressed in-situ ROS, thus exhibiting better theranostic performance in the autoimmune hepatitis and hind paw edema mouse models, including more salient imaging signals and better therapeutic efficacy via inhibiting NF-κB pathway and suppressing NLRP3 inflammasome activation. This work may provide perceptions for designing other actively-targeting theranostic nanosystems for various inflammatory diseases.

Multilevel Chirality Transfer from Amino Acid Derivatives to Circularly Polarized Luminescence-Active Nanoparticles in Aqueous Medium.

Chirality at different levels is widely observed in nature, but the clue to connect it all together, and the way chirality transfers among different levels are still obscure. Herein, a l-/d-lysine-based self-assembly system was constructed, in which two-step chirality transfer among three different levels was observed in aqueous solution. The chirality originated from the point chirality of amino acid derivatives l-/d-PyLys hydrochloride, and was transferred to the planar conformational chirality of water-soluble pillar[5]arene pR-/pS-WP5. Then, with the aid of pR-/pS-WP5, nanoparticles were formed that exhibited L-/R-handed circularly polarized luminescence with a dissymmetry factor of up to ±0.001, arising from pyrene chiral excimers. This multilevel chirality transfer not only provides a perspective to trace potential clues, and to pursue certain ways by which the chirality transfers, but also offers a strategy to create controllable CPL emission in aqueous media.

Micronization and coating of bioflavonoids extracted from Citrus sinensis L. peels to preparation of sustained release pellets using supercritical technique

Bioflavonoids such as hesperidin and hesperetin as anticancer and antioxidant agents are widely used in the formulation of many herbal drugs. Recently, promising evidence for the prevention and treatment of COVID 19 using these compounds has been reported. Unfortunately, these compounds are often insoluble in aqueous media and have low stability in gastric acid environment. These factors reduced the bioavailability of related oral dosage forms in digestive system. Reduction of particle size and controlled release delivery system can decline the mentioned problems. In the presented research, extraction of bioflavonoids from Citrus sinensis L. (sweet orange) peels was performed using supercritical carbon dioxide. Experimental central composite design was employed for determination of optimal conditions. Qualification analysis was performed using LC–MS, and hesperidin and hesperetin were identified in herbal extract. Micronization and coating of the flavonoids nanoparticles on sugar spheres have been performed using an inhouse developed supercritical technique. Characterization of coated nanoparticles was done using FESEM and ImageJ software. The in vitro antioxidant activity of coated samples was investigated by ferrous ion chelating activity. According to the extraction results, concentration of ethanol as organic co-solvent has the greatest effect on the extraction yield. Analysis of FESEM images illustrated that nanoparticles of extract components with particle size distribution of 5–100 nm were coated successfully. The solubility and antioxidant activity of nanoparticles in aqueous media have increased significantly compared to original form. This process led to increasing dissolution rate and improving the oral bioavailability of flavonoids.Graphical abstract

Synthesis of copper and copper oxide nanoparticles with different morphologies using aniline as reducing agent

Copper nanoparticles (CuNPs) are synthesized by chemical reduction of CuSO4·5H2O salt in presence of aniline as reducing agent. The effects of CuSO4·5H2O concentration, reaction temperature, molar ratio of [aniline]/[CuSO4·5H2O], reaction media and presence of surface capping agent of sodium dodecyl sulfate (SDS) on the morphology and size of CuNPs are investigated. The results of X-ray diffraction (XRD) and UV-VIS-NIR spectroscopy exhibited that CuNPs tend to form cupric oxide (CuO) and cuprous oxide (Cu2O) nanoparticles in aqueous media, but choosing ethylene glycol as reaction media diminished the copper oxide formation with acting as surface capping agent. Field emission scanning electron microscopy (FE-SEM) images showed that prepared nanoparticles had morphology of almond-like and flaky-like in water and ethylene glycol whereas presence of SDS led to formation spherical particles. Also, increasing CuSO4·5H2O concentration in ethylene glycol increased the specific surface area (SSA) of CuNPs.

In Vitro Degradation and Cytotoxicity Response of Biobased Nanoparticles Prepared by Thiol-ene Polymerization in Miniemulsion

Biodegradability is a key feature for the application of polymeric devices in medicine. This study reports an experimental and theoretical study of the degradation of poly(thioether-ester) (PTEe) nanoparticles in aqueous media. The α,ω-diene diester derived from vegetable oil, 1,3-propylene diundeca-10-polenoate (Pd10e), was used as monomer in the solvent-free synthesis of Pd10e-based nanoparticles (A-PTEe nanoparticles) via thiol-ene miniemulsion polymerization. The theoretical partition coefficients of A-PTEe and a PTEe based on dianhydro-d-glucityl diundec-10-enoate (DGU) (B-PTEe nanoparticles) were calculated using density functional theory (DFT), in order to compare their degradation behavior. The results showed that A-PTEe is more hydrophilic than B-PTEe, thus indicating the possible faster degradation of the former. The experimental degradation studies showed that, in fact, A-PTEe nanoparticles are faster degraded than B-PTEe, presenting substantial molecular weight decrease, which confirms the theoretical results. The effects of degradation could be observed in the chemical composition and thermal properties of the polymer. Considering its applicability potential as a biomaterial due to its fast degradation behavior, the cytotoxicity of A-PTEe nanoparticles and its degradation products were evaluated. In vitro assays confirmed the biocompatibility of A-PTEe nanoparticles and its degradation products when exposed on fibroblasts and red blood cells. These results suggest A-PTEe nanoparticles can be promising candidates as biobased nanocarriers for biomedical applications.

Finding Nano: Challenges Involved in Monitoring the Presence and Fate of Engineered Titanium Dioxide Nanoparticles in Aquatic Environments

In recent years, titanium dioxide (TiO2) has increasingly been used as an inorganic ultraviolet (UV) filter for sun protection. However, nano-TiO2 may also pose risks to the health of humans and the environment. Thus, to adequately assess its potential adverse effects, a comprehensive understanding of the behaviour and fate of TiO2 in different environments is crucial. Advances in analytical and modelling methods continue to improve researchers’ ability to quantify and determine the state of nano-TiO2 in various environments. However, due to the complexity of environmental and nanoparticle factors and their interplay, this remains a challenging and poorly resolved feat. This paper aims to provide a focused summary of key particle and environmental characteristics that influence the behaviour and fate of sunscreen-derived TiO2 in swimming pool water and natural aquatic environments and to review the current state-of-the-art of single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) approaches to detect and characterise TiO2 nanoparticles in aqueous media. Furthermore, it critically analyses the capability of existing fate and transport models to predict environmental TiO2 levels. Four particle and environmental key factors that govern the fate and behaviour of TiO2 in aqueous environments are identified. A comparison of SP-ICP-MS studies reveals that it remains challenging to detect and characterise engineered TiO2 nanoparticles in various matrices and highlights the need for the development of new SP-ICP-MS pre-treatment and analysis approaches. This review shows that modelling studies are an essential addition to experimental studies, but they still lack in spatial and temporal resolution and mostly exclude surface transformation processes. Finally, this study identifies the use of Bayesian Network-based models as an underexplored but promising modelling tool to overcome data uncertainties and incorporates interconnected variables.

Self-Assembled Binaphthyl-Bridged Amphiphilic AABB Phthalocyanines: Nanostructures for Efficient Antimicrobial Photodynamic Therapy.

Herein, the photodynamic activity of phthalocyanine (pc)-assembled nanoparticles against bacterial strains is demonstrated. The photosensitizers (PS) studied in this work are two chiral ZnII Pcs (PS-1 and PS-2), with an AABB geometry (where A and B refer to differently substituted isoindole constituents). They contain differently functionalized, chiral binaphthyloxy-linked A isoindole units, which determine the hydrophobicity of the system, and cationic methyl pyridinium moieties in the other two isoindoles to embody hydrophilicity. Both compounds have the ability to self-assemble into nanoparticles in aqueous media and have proved efficient in the photo-inactivation of Staphylococcus aureus and Escherichia coli, selected as models of Gram-positive and Gram-negative bacteria. The average size of the nanoparticles was determined by substitution at the binaphthyl core and, in turn, influences the toxicity of the PS. Thus, PS-1, presenting a nonsubstituted binaphthyl core, forms larger nanoparticles with a larger cationic surface than the octyl-functionalized PS-2. Although both PSs present similar structure and photophysical features, the self-assembled nanostructures of PS-1 are more effective at killing both types of strain, showing an outstanding photo-inactivation capacity with the Gram-negative E. coli.

Highly selective and sensitive electrochemical sensing of trace Zn2+ ions, by grafted Tricholoma mushroom polysaccharide/Ag composite nanoparticles in aqueous medium

Herein, we report a highly sensitive, selective and simple electrochemical sensor for the detection of Zn2+ ions in less than 1 nM concentration range in aqueous environment. A naturally occurring and frequently cultivated Tricholoma mushroom polysaccharide is used for the preparation of novel sensor. In the present investigation we demonstrate an electrochemical sensor, grafted Tricholoma mushroom polysaccharide‐based silver composite nanoparticles (TMPSGP‐Ag NPs) which show remarkable electrochemical sensing performance of Zn2+ ions without interfering with the other relevant metal ions. The sensing performance is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimised condition. The limit of detection (LOD) is found to be 0.53 nM, which is much lower than some other reported works as well as lower than the limit of World Health Organization (WHO). The stability, reproducibility and repeatability properties of the sensor are examined where a satisfactory result is obtained. The practical application of the proposed sensor is tested by the detection of Zn2+ ions using river water sample with an excellent performance. Therefore, the developed sensor can be used as a highly efficient and effective Zn2+ ions detector in aqueous medium.

Improving the stability of plasmonic magnesium nanoparticles in aqueous media.

This work describes two different core–shell architectures based on Mg nanoparticles (NPs) synthesised in order to improve Mg's stability in aqueous solutions. The shell thickness in Mg–polydopamine NPs can be modulated from 5 to >50 nm by ending the polymerization at different times; the resulting structures stabilize the metallic, plasmonic core in water for well over an hour. Mg–silica NPs with shells ranging from 5 to 30 nm can also be prepared via a modified Stöber procedure and they retain optical properties in 5% water-in-isopropanol solutions. These new architectures allow Mg nanoplasmonics to be investigated as an alternative to Ag and Au in a broader range of experimental conditions for a rich variety of applications.

Pyrene Associates As a New Highly Sensitive Sensor for Monitoring the Content of Silver Nanoparticles in Aqueous Media

A study is performed of the luminescence of pyrene molecules solubilized in a supramolecular ordered structure formed as a result of the self-organization of molecules of cationic surfactant cetyltrimethylammonium bromide (CTAB) in the presence of trace amounts of aggregated silver nanoparticles (NPs). The study is performed using dilute aqueous solutions of CTAB and at CTAB concentrations that exceed the critical micelle concentration. The formation of a number of pyrene associates (high-energy excimers) that glow in the short-wavelength region of the optical spectrum is observed, relative to the glow of a low-energy dimer (470 nm), and the intensity of the glow of the resulting associates depends on the concentration of silver aquasol introduced into the considered solution. The phenomenon is explained by the location of pyrene molecules near the surfaces of aggregated silver nanoparticles, which have high-density electromagnetic fields caused by surface plasmon resonance. It is found that pyrene associates can be used as sensors for determining trace amounts of silver NPs in aqueous media.