Search Results (3,134)

The increasing use of nanomaterials in modern industries and consumer products has led to the release of various contaminants into wastewater streams and the surrounding environment. However, nanoparticle detection and characterisation in wastewater remain analytically challenging due to the presence of dissolved metals, suspended solids, natural colloids, and heterogeneous particulate matter. In this study, we demonstrate an integrated analytical workflow combining single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) with transmission electron microscopy (TEM) and ImageJ version 1.54g image analysis for the comprehensive characterisation of engineered nanoparticles (ENPs) in industrial wastewater. In contrast to earlier research on well-defined manufactured nanoparticles in controlled laboratory suspensions, this work uses complementary analytical techniques to analyse real industrial wastewater, allowing for quantitative elemental analysis, particle sizing, and morphological confirmation in South Africa. Additionally, a supporting bibliometric analysis serves as supporting evidence to identify research trends and knowledge gaps, revealing limited application of integrated analytical workflows to complex industrial wastewater matrices. Analytical conditions were optimised according to the recommendations of previous publications, with a dwell period of 3 μs to limit particle coincidence and enable reliable single-particle detection. The combined approach was effectively applied to characterise silver (AgENPs) and gold (AuENPs) nanoparticles with median particle sizes of 14 nm and 8 nm, respectively. The particle number concentrations ranged from 3.00 × 10⁷ to 3.60 × 10⁸ particles L⁻¹ for AgENPs and 3.80 × 10⁸ particles L⁻¹ for AuENPs. Comparing dissolved metal concentrations with particle mass concentrations gave some insight into the partitioning of metals between the dissolved and nanoparticulate fractions. Moreover, bibliometric analysis has shown that despite the exponential growth of research on SP-ICP-MS, very few studies have simultaneously employed analytical techniques to describe nanoparticles in complicated industrial wastewater matrices. These results show the utility of integrating complementary analytical approaches for the reliable characterisation of particulate pollutants in environmentally relevant samples and promote improved environmental monitoring and risk assessment of manufactured nanoparticles. Full article

As a core component of vitamin B12, Co²⁺ is closely associated with the health, life performance, and productivity of ruminants. Therefore, the selective and sensitive detection of Co²⁺ is of great significance. In this work, using the Au–S bond as an “anchor”, a ternary nanocomposite (CDs-AuNPs-GSH) with synergistic functions was constructed by combining gold nanoparticles (AuNPs) with glutathione (GSH) through hydrogen bonding and electrostatic interactions with functional groups on the surface of carbon dots (CDs). The resulting nanocomposite was employed as a fluorescence sensor for Co²⁺ detection. Under optimal conditions at pH 6.0, the sensor exhibited a good linear relationship over the Co²⁺ concentration range of 0.5–125.0 mM, with a limit of detection (LOD) of 0.38 mM. The interaction mechanism between Co²⁺ and the composite was systematically investigated using various characterization methods. The results indicated that Co²⁺, owing to its strong coordination ability, enriches on the surface of the composite, subsequently triggering dynamic fluorescence quenching via an electron transfer pathway. The sensor was successfully applied to determine Co²⁺ in mixed livestock and poultry feed samples, with recovery rates ranging from 89.4% to 103.9%, demonstrating its potential for on-site detection in feed analysis. Full article

The degradation of organic pollutants through photocatalysis is currently a major research focus. Core–shell heterostructures of metal semiconductors have been widely recognized as an effective strategy for enhancing photocatalytic performance, particularly when alloy nanoparticles are incorporated due to their unique electronic and catalytic properties. However, conventional synthetic approaches typically rely on high-temperature and high-pressure conditions, which often induce undesirable particle overgrowth and aggregation. Herein, AuPt bimetallic alloy nanoparticles were successfully fabricated via two successive in situ redox processes under room-temperature and ambient-pressure conditions, which were in situ integrated with Cu₂O to form multilevel core–shell composite particles. Structurally, an octahedral Cu₂O crystal serves as the inner core (denoted as Cu₂O_(O)), sequentially coated with a Cu₂O nanoparticle (denoted as Cu₂O_(P)) interlayer and a AuPt alloy nanoparticle shell. Functionally, the enhanced photocatalytic activity of Cu₂O_(O)@Cu₂O_(P)@AuPt was proven to be attributed to a dual function of AuPt, which includes an adsorption-induced polarized interface and an efficient charge-transfer mediator with the ohmic contact. This work demonstrates a mild and versatile synthetic strategy for constructing semiconductor–alloy heterostructures, offering valuable insights into the rational design of highly efficient and stable photocatalysts. Full article

Osteosarcoma, the most common primary malignant bone tumor in adolescents, faces treatment challenges due to metastasis and chemoresistance. This study developed a novel Au@Rh core–shell nanoparticle system functionalized with indocyanine green (ICG) to overcome hypoxia-limited photodynamic therapy (PDT). Au@Rh nanoparticles were synthesized via wet chemistry and characterized by UV-Vis spectroscopy, TEM, and cyclic voltammetry (CV). The system exhibited a core–shell morphology, well-defined crystalline planes, photothermal conversion and electrocatalytic activity. The Au@Rh nanoparticles (109 nm total size, 90 nm Au core, and 15 nm Rh shell) demonstrated dual functionality: the gold core provided photothermal conversion (a 7 °C temperature increase under NIR irradiation), while the rhodium shell exhibited pH-independent electrocatalytic activity for H₂O₂ decomposition, generating oxygen to alleviate tumor hypoxia. Crucially, the system showed excellent biocompatibility, with no significant cytotoxicity in both osteosarcoma (HOS) or normal osteoblast (hFOB) cells after 48 h of exposure. When activated by NIR irradiation (808 nm, 16.6 J/cm²), the complete Au@Rh-ICG system achieved selective 67% cytotoxicity in HOS cells versus only 30% in hFOB cells, demonstrating targeted therapeutic efficacy. These results position Au@Rh-ICG as a promising theranostic platform for osteosarcoma treatment, combining enhanced PDT with photothermal therapy while addressing tumor hypoxia. Full article

Early detection of lung cancer remains challenging due to the extremely low concentrations of disease-specific biomarkers, which limit the development of highly sensitive and reliable point-of-care (PoC) diagnostic devices. Electrochemical biosensors integrating graphene oxide (GO) and gold nanoparticles (AuNPs) have emerged as promising platforms for the rapid, sensitive, and selective detection of lung cancer biomarkers, enabling more timely diagnosis. Biomarkers such as carcinoembryonic antigen (CEA), cytokeratin-19 fragments (CYFRA 21-1), neuron-specific enolase (NSE), and circulating tumour DNA are increasingly investigated for PoC applications since they can be detected in various biological fluids associated with lung cancer. Nanocomposite materials, particularly GO/AuNP hybrids, provide synergistic advantages by combining the large surface area and abundant functional groups of GO for stable immobilization of biorecognition elements with the excellent conductivity and bioconjugation capability of AuNPs that enhance signal transduction. This review critically discusses key biomarker targets for lung cancer, the properties of GO and Au in biosensing, and the role of AuNP/GO nanocomposites in improving biosensor performance. It further examines the application of electrochemical biosensors for lung cancer biomarker detection, highlighting recent developments. Additionally, the review outlines current challenges limiting clinical translation and PoC implementation, provides recommendations to address these barriers, and discusses future perspectives for improving the detection of low-abundance biomarkers for early lung cancer diagnosis. Ultimately, these technologies seem promising for the development of rapid diagnostic tools equivalent to established platforms such as lateral-flow immunoassays. Full article

Background: Effective management of bone defects remains a major clinical challenge, driving continuous efforts to develop bioactive, localized delivery systems that support bone regeneration. Gold nanoparticles (AuNPs) have gained attention in regenerative medicine for their capacity to modulate cellular activity. Yet, their application in functional delivery systems for bone repair is still limited. Chitosan (CS), a naturally derived biopolymer, exhibits notable osteoinductive properties, particularly when used to modify nanoparticulate carriers. Objectives: In this study, AuNPs and chitosan-coated gold nanoparticles (CS-AuNPs) were formulated, characterized, and incorporated into gel preparations to evaluate their physicochemical properties and therapeutic potential in a rat tibial bone defect model. Methods: AuNPs were synthesized and either left uncoated or coated with CS to enhance biological activity. Both formulations were examined for particle size, zeta potential, X-ray diffraction, and Fourier-transform infrared spectroscopy (FTIR). The resulting nanoparticles were integrated into gel bases, which were assessed for gel strength, swelling index, viscosity, and pH. The in vivo study involved surgically induced bone defects in the tibias of albino rats treated with either formulation. Healing outcomes were assessed via histological analysis, quantification of newly formed bone, immunohistochemical staining, radiographic imaging, and measurement of bone-related markers using RT-qPCR. Results: The CS-AuNP gel formulation demonstrated significantly improved bone regeneration compared to the uncoated counterpart, as evidenced by histological findings, increased bone volume in radiographs, stronger immunohistochemical expression of the VEGF angiogenic protein marker, and increased genetic expression of osteogenic markers. Conclusions: Incorporating CS-AuNPs into gel formulations offers a promising approach for enhancing bone healing. The superior performance of the CS-coated system highlights its potential as a promising localized therapy for managing bone defects. Full article

Nanoparticles combining gold and iron oxide are promising for a wide range of biomedical applications, including photothermal therapy, radiotherapy enhancement, drug delivery, and diagnostic imaging. However, their long-term biodistribution and safety profile remain largely unexplored. Here, we synthesized Fe₃O₄@AuNP core–satellite nanoparticles (Fe₃O₄@AuNPs) using femtosecond laser ablation, functionalized them with 15 kDa polyethylene glycol (PEG), and characterized them using a panel of physicochemical techniques. Healthy C57BL/6 mice received an intravenous injection of Fe₃O₄@AuNPs at 730 mg Au/kg and 82 mg Fe/kg, respectively. Biodistribution was monitored by computed tomography (CT) and magnetic resonance imaging (MRI) over 12 months, after which gold and iron concentrations were measured ex vivo, and long-term toxicity was assessed via histology and blood biochemistry. Nanoparticles accumulated predominantly in the liver and spleen. Quantitative analysis of CT images revealed a gradual decrease in gold content, while MRI showed a progressive reduction in negative contrast in the liver between 6 and 12 months, suggesting possible changes in the Fe₃O₄ core structure. Over the one-year observation period, no differences in behavior or body weight gain were detected between the treated and control groups. Histological examination revealed no pathological changes other than mild age-related alterations. These findings provide a baseline for the long-term behavior of laser-ablated core–satellite Fe₃O₄@AuNPs, which is essential for their further development in diagnostic and theranostic applications. Full article

In this work, we developed a novel, ultrasensitive fluorescence sensing platform for determination of organophosphorus pesticides (OPs), using chlorpyrifos as a representative model analyte. The sensing strategy was constructed upon the key inner filter effect (IFE) between graphitic carbon nitride (g-C₃N₄) nanosheets and silver-coated gold core–shell nanoparticles (Au@Ag NPs). Initially, gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), and Au@Ag NPs were successfully synthesized, and their fluorescence quenching efficiencies toward g-C₃N₄ were systematically evaluated. Owing to the superior spectral overlap with the fluorescence emission of g-C₃N₄, Au@Ag NPs exhibited the most obvious quenching effect and were thereby selected as the optimal quencher for sensor fabrication. Then, acetylcholinesterase (AChE) catalyzed the hydrolysis of acetylthiocholine (ATCH) into thiocholine. The generated thiocholine then induced aggregation of Au@Ag NPs via electrostatic and Ag-S interactions, which reduced the IFE efficiency and ultimately restored the fluorescence of g-C₃N₄. In contrast, the presence of chlorpyrifos effectively inhibits AChE activity, thereby suppressing ATCH hydrolysis and the subsequent aggregation of Au@Ag NPs. The fluorescence intensity of g-C₃N₄ was quenched by Au@Ag NPs and the signal was low. Under optimal experimental conditions, the response signal was found to be proportional to chlorpyrifos (CPF). This work presents a rapid, cost-effective, and highly sensitive approach for CPF residue analysis, holding great potential for applications in food safety monitoring and environmental surveillance. Full article

The presence of aflatoxin B1 (AFB1) is ubiquitous in the environment, and it is considered one of the most powerful natural carcinogenic substances. In this study, a highly sensitive electrochemical aptasensor was designed to detect aflatoxin B1 (AFB1) in peanuts. Iron–cobalt-doped magnetic carbon (Fe-Co/NPC) was used to enhance the conductivity of the electrode and catalytic performance, providing an increased specific surface area. Gold nanoparticles (AuNPs) were used to immobilize an aptamer. And cDNA-polyacrylic acid (cDNA-PAA) nanogels served as a high-density carrier for cDNA and an active signal amplification unit, significantly increasing the charge transfer resistance (Rct) through steric hindrance and electrostatic repulsion. Unlike traditional aptasensors that relied on passive blocking agents, we designed a competitive displacement mechanism. AFB1 competed with cDNA-PAA during detection in order to bind to the aptamer, which resulted in the removal of the non-conductive complex and a substantial increase in the electrochemical signal. Under the optimal conditions, the aptasensor had a linear response range of 1–1000 ng/L and a limit of detection (LOD) of 0.3 ng/L. It displayed high specificity, reproducibility, and stability. In spiked peanut samples, the recoveries ranged from 98.04% to 100.86%. Due to its sensitivity and reliability, this aptasensor has a great determination of AFB1 in food safety applications. Full article

Gold nanoparticles (AuNPs) can improve hole injection in OLEDs but may also induce LSPR-related optical perturbation and exciton quenching. To exploit their hole-injection-promoting effect while suppressing possible exciton quenching, AuNPs with diameters of 3.5–4.0 nm were synthesized by citrate reduction and doped into PEDOT:PSS as a hole injection layer modifier. Photoluminescence measurements revealed absorption-related wavelength-dependent optical perturbation from exposed AuNPs, with the strongest effect on red emission and only a minor effect on blue emission. AuNPs embedded in PEDOT:PSS caused only slight changes in PL spectra and PL decay behavior, indicating that obvious exciton quenching was avoided. OLEDs with AuNP-doped PEDOT:PSS exhibited reduced turn-on voltages and increased maximum current efficiencies from 22.4 to 27.0 cd/A, 7.64 to 15.6 cd/A, and 16.8 to 29.0 cd/A for blue, red, and green devices, respectively. These results indicate that sub-5 nm AuNPs embedded in PEDOT:PSS can improve device performance by enhancing hole-injection capability, while their wavelength-dependent exciton-quenching effect is negligible. Full article

Sickle cell disease (SCD) and thalassemia are genetic disorders that necessitate accurate diagnosis for effective management and improved patient outcomes. The advent of nanotechnology has paved the way for innovative, precise detection methods, offering enhanced sensitivity and specificity. The present systematic review aims to assess the analytical performance of nanotechnology-based detection methods for SCD and thalassemia, with a focus on evaluating the analytical performance and identifying the most sensitive nanotechnology-based techniques. An extensive literature search was conducted across five databases (ScienceDirect, PubMed, Embase, Google Scholar), yielding 23 studies that met the inclusion criteria. These studies showcased the potential of nanotechnology-based methods for detecting SCD and thalassemia. The studies utilized diverse samples, including blood, serum, genomic DNA, and purchased oligonucleotides, with most reporting limit of detection (LOD) values. Specifically, gold nanoparticles (AuNPs) exhibited exceptional sensitivity, with detection limits ranging from 2.6 aM to 0.035 pM. Surface modification and functionalization of AuNPs significantly enhance their detection capabilities. Other nanostructures, including silver nanoparticles, quantum dots, and graphene quantum dots, also demonstrate promising diagnostic capabilities. The results showed that nanotechnology-based methods demonstrated improved analytical sensitivity, with LOD ranging from 2.6 aM to 50 nM. This systematic review provides a comprehensive overview of the analytical performance of nanotechnology-based detection methods, shedding light on their potential to revolutionize diagnosis and treatment. Overall, it highlights the transformative potential of nanotechnology in improving molecular diagnostic accuracy for SCD and thalassemia. Full article

2,4-Dichlorophenoxyacetic acid (2,4-D) is an extensively applied organic compound, primarily for agricultural weed control and plant growth agents. Although 2,4-D usually exists in the environment in low volumes, the detection of 2,4-D is critical for human health and environmental safety. In this work, a biophotonic biosensor was fabricated by coating the surface of a tapered optical fiber with gold nanoparticles (AuNPs) to excite the localized surface plasmon resonance (LSPR) and functionalizing the fiber with molybdenum disulfide nanosheets (MoS₂-NSs)/zinc oxide nanowires (ZnO-NWs) to extend the effective sensing area. Due to the inhibitory effect of 2,4-D on the hydrolytic activity of ALP, the refractive index (RI) around the sensor surface changes, leading to a shift in the LSPR peak wavelength. According to this sensing technique, the sensor can detect concentrations in the range of 1–10 mg/L, with a limit of detection (LOD) of 0.29 mg/L. The stability, repeatability and selectivity tests show that the sensor has good stability and selectivity. In the actual sample detection experiment, the recovery rates of apples and Chinese cabbage were 96.2–100.4% and 83.8–108.8%, respectively, which indicated that the detection method had good accuracy for the detection of target substances in actual samples. Thus, the proposed sensor has an important application in the detection of 2,4-D herbicides. Full article

Neuropeptide Y (NPY) is a stress-modulating neuropeptide and a promising biomarker for non-invasive assessment. Herein, a sensitive electrochemical aptasensor was developed on reduced graphene oxide/gold nanoparticle (rGO/AuNP)-modified screen-printed electrodes for selective NPY detection. A methylene blue (MB)-labeled NPY-specific aptamer was immobilized on the electrode surface through Au–S chemistry, and square-wave voltammetry (SWV) was used for signal readout. The rGO/AuNP-modified interface provided high conductivity and a large effective surface area, facilitating electron transfer and probe immobilization. Under optimized conditions, the aptasensor exhibited a linear detection range of 10–10,000 pg mL⁻¹ in PBS with a low detection limit of 1.17 pg mL⁻¹ and good linearity (R² = 0.991). In addition, the sensor showed satisfactory selectivity, reproducibility, and mechanical stability. Recovery tests in artificial sweat yielded recoveries of 91.8–107.8% with relative standard deviations below 5%, demonstrating good analytical accuracy in complex matrices. Combined with an agarose-hydrogel-assisted sampling interface and a reverse-iontophoresis-compatible wearable platform, this low-cost and facile sensing strategy provides a portable proof-of-concept approach for NPY analysis in artificial sweat and shows potential for future wearable-oriented biofluid monitoring. Full article

A biological/synthetic hybrid graft copolymer was obtained by grafting poly(acrylic acid) (PAA, synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization) to amylopectin (AMP). The novel graft copolymer presents amphiphilic properties due to the inherent insolubility of AMP in water and was further utilized as a mediator for the synthesis of gold nanoparticles (AuNPs) following an environmentally friendly in situ procedure. The AMP-g-PAA copolymer formation by the interaction of the PAA end groups with the C(6)-OH groups on an AMP backbone was confirmed by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and 1D (proton (¹H NMR) and carbon (¹³C NMR) nuclear magnetic resonance, and Distortionless Enhancement by Polarization Transfer (DEPT)) and 2D (correlation (COSY) and heteronuclear single quantum coherence (HSQC)) spectroscopies. The calculated degree of substitution of 1.17 suggests that the grafting was done at one OH from the three in an anhydroglycosidic unit (AGU) (preferably at that in C6 position), with a mean grafting efficiency of 76%. Additional information obtained using thermogravimetric analysis shows that the thermal decomposition of AMP-g-PAA occurs in two steps, with a residual mass of ~16 wt% at 700 °C, higher than AMP or PAA, indicating increased thermal stability of the copolymer. Dynamic and electrophoretic light scattering (DLS and ELS) measurements were used to determine the hydrodynamic size and ionic charge of the AMP-g-PAA self-assemblies in aqueous solution as well as their stability. The AMP-g-PAA was subsequently tested as a reducing agent in the environmentally friendly synthesis of AuNPs in aqueous solution, at different incubation temperatures, reaction duration, and inorganic/polymer weight ratios. The development of the surface plasmon resonance band of AuNPs, observed in UV–vis spectra, was consistently monitored over the reaction time. DLS analysis indicated time-dependent changes in the AuNPs’ particle size distributions, while scanning transmission electron microscopy confirmed that the AuNPs formed at the inorganic/polymer weight ratio of 0.36 and at 60 °C were predominantly well-dispersed, spherical-shaped nanoparticles. The AuNPs synthesized in situ within the copolymer matrix did not introduce additional cytotoxicity compared to the parent copolymer alone, with the composites representing a promising safety baseline for further investigation in biomedical applications. Full article

Paracetamol (PA) ranks among the most frequently prescribed over-the-counter analgesic and antipyretic agents worldwide; nonetheless, overdose scenarios are associated with severe hepatotoxic and nephrotoxic consequences, while its incomplete metabolic removal renders it a persistent micropollutant in surface and wastewater systems. These concerns underscore the urgent need for rapid, cost-efficient, and highly sensitive analytical tools capable of quantifying PA at trace levels in complex matrices. In the present study, spherical gold nanoparticles (AuNPs) were fabricated through an environmentally benign route exploiting an aqueous extract of Juniperus sp. leaves as the reducing and capping agent, with polyvinylpyrrolidone (PVP) serving as an additional colloidal stabilizer. The resulting nanoparticles were immobilized on a glassy carbon electrode to construct an AuNPs/PVP/GCE sensing platform. Physicochemical characterization by UV–Vis spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) verified the spherical morphology, narrow size distribution, and colloidal stability of the synthesized AuNPs, and further confirmed a 3.5-fold enlargement of the electroactive surface area relative to the unmodified electrode. Under fully optimized conditions, the fabricated sensor delivered a well-defined linear voltammetric response toward PA oxidation across the concentration interval of 0.05–0.31 µM (R² = 0.9939), with a limit of detection of 0.024 µM and a limit of quantification of 0.080 µM. The sensor retained its analytical accuracy in the presence of common co-existing species, including ascorbic acid, uric acid, dopamine, caffeine, ibuprofen, and adrenaline. Quantitative determination of PA in commercial tablet formulations via the standard addition approach yielded results in close agreement with the declared content, confirming the practical suitability of the AuNPs/PVP/GCE platform for routine pharmaceutical quality control. Full article