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Alzheimer’s disease (AD) is a major health challenge worldwide, especially among the elderly. The disease is associated with cognitive and memory deficits. This study investigated the effect of Hibiscus sabdariffa synthesized-gold nanoparticles (HS-AuNPs) on AlCl3-induced memory deficits in rats. Forty-two male Wistar rats were divided into six groups (n = 7). Group I served as control. Rats in group II - V were exposed to AlCl3 (100 mg/kg) to induce AD. Group III - V rats were treated with 5 mg/kg donepezil, 5 and 10 mg/kg HS-AuNPs, respectively, for 14 days. Behavioral tests were carried out on the rats on day 28 and 42. At the end of animal experiment, rats were sacrificed and used for various biochemical assays and gene expression. The AD rats showed memory and learning impairment, and these conditions were ameliorated by HS-AuNPs. Significant (p

In this work, gold nanoparticles@Ti3C2 MXenes nanocomposites with excellent properties were combined with toehold-mediated DNA strand displacement reaction to construct an electrochemical circulating tumor DNA biosensor. The gold nanoparticles were synthesized in situ on the surface of Ti3C2 MXenes as a reducing and stabilizing agent. The good electrical conductivity of the gold nanoparticles@Ti3C2 MXenes composite and the nucleic acid amplification strategy of enzyme-free toehold-mediated DNA strand displacement reaction can be used to efficiently and specifically detect the non-small cell cancer biomarker circulating tumor DNA KRAS gene. The biosensor has a linear detection range of 10 fM −10 nM and a detection limit of 0.38 fM, and also efficiently distinguishes single base mismatched DNA sequences. The biosensor has been successfully used for the sensitive detection of KRAS gene G12D, which has excellent potential for clinical analysis and provides a new idea for the preparation of novel MXenes-based two-dimensional composites and their application in electrochemical DNA biosensors.

Megavoltage radiotherapy and cisplatin-based chemotherapy are the primary glioblastoma treatments. Novel nanoparticles have been designed to reduce adverse effects and boost therapeutic effectiveness. In the present study, we synthesized the SPIO@AuNP-Cisplatin-Alginate (SACA) nanocomplex, composed of a SPIO core, a gold shell, and an alginate coating. SACA was characterized using transmission electron microscopy (TEM) and dynamic light scattering (DLS). U87-MG human glioblastoma cells and the HGF cell line (a healthy primary gingival fibroblast) were treated in multiple groups by a combination of SACA, cisplatin, and 6 MV X-ray. The MTT assay was used to assess the cytotoxicity of cisplatin and SACA (at various concentrations and for 4 h). Following the treatments, apoptosis and cell viability were evaluated in each treatment group using flow cytometry and the MTT assay, respectively. The findings demonstrated that the combination of SACA and 6 MV X-rays (at the doses of 2 and 4 Gy) drastically decreased the viability of U87MG cells, whereas the viability of HGF cells remained unchanged. Moreover, U87MG cells treated with SACA in combination with radiation exhibited a significant increase in apoptosis, demonstrating that this nanocomplex effectively boosted the radiosensitivity of cancer cells. Even though additional in vivo studies are needed, these findings suggest that SACA might be used as a radiosensitizer nanoparticle in the therapy of brain tumors.

Single‐particle tracking and optical tweezers are powerful techniques for studying diverse processes at the microscopic scale. The stochastic behavior of a microscopic particle contains information about its interaction with surrounding molecules, and an optical tweezer can further facilitate this observation with its ability to constrain the particle to an area of interest. Although these techniques found their initial applications in biology, they can also shed new light on microscopic interface phenomena by unveiling nanoscale morphologies and molecular‐level interactions in real time, which are obscured in traditional ensemble analysis. Here, the application of single‐particle tracking and optical tweezers are demonstrated for studying molecular interactions at solid–liquid interfaces. Specifically, the surfactant behaviors at the water–glass interface are investigated by tracing gold nanoparticles that are optically trapped on these molecules. The underlying mechanisms governing the particle motion, which can be explained by hydrophobic interactions, disruptions, and rearrangements among surfactant monomers at the interfaces, are discovered. These interpretations are further supported by statistical analysis of an individual trajectory and comparison with theoretical predictions. The findings provide new insights into the surfactant dynamics and also illustrate the promise of single‐particle tracking and optical manipulation for studying nanoscale physics and chemistry of surfaces and interfaces. [ABSTRACT FROM AUTHOR]

A breakthrough in cosmeceuticals by utilizing insects as major ingredients in cosmetic products is gaining popularity. Therefore, the interest in rare sources of ingredients, for instance, from the Oryctes rhinoceros beetle, can bring huge benefits in terms of turning pests into wealth. In this study, curcumin was chosen as the active ingredient loaded into chitosan-gold nanoparticles (CCG-NP). Curcumin is unstable and has poor absorption, a high rate of metabolism, and high sensitivity to light. These are all factors that contribute to the low bioavailability of any substance to reach the target cells. Therefore, chitosan extracted from O. rhinoceros could be used as a drug carrier to overcome these limitations. In order to overcome these limitations, CCG-NPs were synthesized and characterized. Chitosan was isolated from O. rhinoceros and CCG-NPs were successfully synthesized at 70 °C for 60 min under optimal conditions of a reactant ratio of 2:0.5 (0.5 mM HAuCl4: 0.1% curcumin). Characterizations of CCG-NP involved FTIR analysis, zeta potential, morphological properties determination by FE-SEM, particle size analysis, crystallinity study by XRD, and elemental analysis by EDX. The shape of the CCG-NP was round, its size was 128.27 d.nm, and the value of the zeta potential was 20.2 ± 3.81 mV. The IC50 value for cell viability is 58%, indicating a mild toxicity trait. To conclude, CCG-NP is a stable, spherical, nano-sized, non-toxic, and homogeneous solution. [ABSTRACT FROM AUTHOR]

Asthma is an inflammatory disease that affects the airways. Inflammation of the airway and reversible bronchoconstriction eventually lead to obstruction of the airways, breathlessness and asthma attack. Gold nanoparticles are among the most widely used nanoparticles and have many applications for pharmaceutical and medical purposes. Cortistatin is a neuropeptide that exhibits anti-inflammatory effects. In this study, spherical gold nanoparticles were conjugated to the Cortistatin peptide, for effective and targeted drug delivery to the airways of asthmatic mice. After synthesizing spherical gold nanoparticles and conjugation the Cortistatin, asthma model was produced and treatment with a nano-drug. The levels of inflammatory cytokines, Specific and total IgE, inflammatory gene expression, the number of goblet cells, and the amount of mucus secretion and eosinophilic inflammation in lung tissues were studied. The results showed that Cortistatin-nanoparticle could control allergic and inflammatory factors and the anti-inflammatory effects of Cortistatin peptide-bound nanoparticle are far greater than those of the peptide alone. Increasing the anti-inflammatory effect of peptide-bound nanoparticle versus peptide alone, confirmed the effective, targeted and correct drug delivery of peptide-nanoparticle combination to inflamed areas in lung tissue. [ABSTRACT FROM AUTHOR]

In this work, an electrochemical aptasensor was described for the determination of prostate‐specific antigen (PSA). Aptamer chains were decorated on the surface of a glassy carbon electrode (GCE) via carbon quantum dots/Au nanoparticles (Au/CQD). Structural analysis that was used to characterize the prepared materials shows that Au/CQD nanoparticles synthesized in a spherical shape with an average size of 70 nm. Furthermore, the combination of Au nanoparticles with CQD resulted in formation of crystalline the structure of the Au/CQD composite. To study the electrochemical performance of the prepared aptasensor, cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy were used. The results show that the aptasensor has a good selectivity to PSA over other biomaterials with the time optimized about 30 min. K4[Fe(CN)6] was used as an electrochemical probe with the limit of detection about 2 fg⋅mL–1. To avoid the hazardous nature of K4[Fe(CN)6], a label‐based aptasensor was prepared using methylene blue as an electrochemical signal producer. They provide the capability of electrochemical detection in buffer phosphate solution with high sensitivity. [ABSTRACT FROM AUTHOR]

Dacarbazine (DB) is an antineoplastic drug extensively used in cancer therapy. However, present limitations on its performance are related to its low solubility, instability, and non-specificity. To overcome these drawbacks, DB was included in β-cyclodextrin (βCD), which increased its aqueous solubility and stability. This new βCD@DB complex has been associated with plasmonic gold nanoparticles (AuNPs), and polyethylene glycol (PEG) has been added in the process to increase the colloidal stability and biocompatibility. Different techniques revealed that DB allows for a dynamic inclusion into βCD, with an association constant of 80 M−1 and a degree of solubilization of 0.023, where βCD showed a loading capacity of 16%. The partial exposure of the NH2 group in the included DB allows its interaction with AuNPs, with a loading efficiency of 99%. The PEG-AuNPs-βCD@DB nanosystem exhibits an optical plasmonic absorption at 525 nm, a surface charge of −29 mV, and an average size of 12 nm. Finally, laser irradiation assays showed that DB can be released from this platform in a controlled manner over time, reaching a concentration of 56 μg/mL (43% of the initially loaded amount), which, added to the previous data, validates its potential for drug delivery applications. Therefore, the novel nanosystem based on βCD, AuNPs, and PEG is a promising candidate as a new nanocarrier for DB. [ABSTRACT FROM AUTHOR]

This work demonstrates the incorporation of gold nanoparticles (AuNPs) into crosslinker-free poly(N-isopropylacrylamide), PNIPAM, particles in situ and the examination of their structural and catalytic properties. The formation process of the AuNPs across the crosslinker-free PNIPAM particles are compared to that of crosslinked PNIPAM particles. Given the relatively larger free volume across the crosslinker-free polymer network, the AuNPs formed by the in situ reduction of gold ions are detectably larger and more polydisperse, but their overall integration efficiency is slightly inferior. The structural features and stability of these composite particles are also examined in basic and alcoholic solvent environments, where the crosslinker-free PNIPAM particles still offer comparable physicochemical properties to the crosslinked PNIPAM particles. Interestingly, the crosslinker-free composite particles as a colloidal catalyst display a higher reactivity toward the homocoupling of phenylboronic acid and reveal the importance of the polymer network density. As such, the capability to prepare composite particles in a controlled polymer network and reactive metal nanoparticles, as well as understanding the structure-dependent physicochemical properties, can allow for the development of highly practical catalytic systems. [ABSTRACT FROM AUTHOR]

A key process in the development of atherosclerotic plaques is the recruitment of monocytes into the artery wall. Using spectral photon-counting computed tomography we examine whether monocyte deposition within the artery wall of ApoE-/- mouse can be detected. Primary mouse monocytes were labelled by incubating them with 15 nm gold nanoparticles coated with 11-mercaptoundecanoic acid The monocyte uptake of the particle was confirmed by electron microscopy of the cells before injection into 6-week-old apolipoprotein E deficient (ApoE-/-) mouse that had been fed with the Western diet for 10 weeks. Four days following injection, the mouse was sacrificed and imaged using a MARS spectral photon counting computed tomography scanner with a spectral range of 7 to 120 KeV with five energy bins. Imaging analysis showed the presence of X-ray dense material within the mouse aortic arch which was consistent with the spectral characteristic of gold rather than calcium. The imaging is interpreted as showing the deposition of gold nanoparticles containing monocytes within the mouse aorta. The results of our study determined that spectral photon-counting computed tomography could provide quantitative information about gold nanoparticles labelled monocytes in voxels of 90 × 90 × 90 µm3. The imaging was consistent with previous micro-CT and electron microscopy of mice using the same nanoparticles. This study demonstrates that spectral photon-counting computed tomography, using a MARS small bore scanner, can detect a fundamental atherogenic process within mouse models of atherogenesis. The present study demonstrates the feasibility of spectral photon-counting computed tomography as an emerging molecular imaging modality to detect atherosclerotic disease. [ABSTRACT FROM AUTHOR]

This work demonstrates the rapid coating of gold nanoparticles (AuNPs) onto electrospun composite polyacrylonitrile (PAN) nanofibers containing a large amount of graphene oxide (GO) and reduced graphene oxide (rGO) for photothermally-driven applications. A modification of GO with a cationic surfactant greatly improves its loading efficiency into the PAN nanofibers, and the subsequent hydrazine treatment readily converts the integrated GO into rGO. Rapid loading of AuNPs onto these membranes results in measurably higher photothermal heating characteristics than the pristine PAN, GO-PAN, and rGO-PAN membranes under a solar-simulated light source. The light-induced heating properties are then utilized in the removal of organic dyes in an aqueous solution. While the GO-PAN and rGO-PAN membranes remove the dyes via physical adsorption, the AuNP-loaded membranes show an additional catalytic decomposition process, resulting in detectably faster removal rates. The degradation of the organic dyes is accelerated under a solar simulated light source due to the light-enhanced heating and photocatalytic properties of the integrated AuNPs. The ability to maximize the dual properties of these membranes can greatly reduce toxic organic pollutants, which can lead to the development of practical water purification systems under sunlight irradiation. [ABSTRACT FROM AUTHOR]

The challenges of a heme protein and enzyme-based H2O2 sensor was subdued by developing a highly sensitive and practically functional amperometric gold nanoparticles (Au NPs)/SnO2 nanofibers (SnO2 NFs) composite sensor. The composite was prepared by mixing multiporous SnO2 NFs (diameter: 120–190 nm) with Au NPs (size: 3–5 nm). The synthesized Au NPs/SnO2 NFs composite was subsequently coated on a glassy carbon electrode (GCE) and displayed a well-defined reduction peak during a cyclic voltammetry (CV) analysis. The SnO2 NFs prevented the aggregation of Au NPs through its multiporous structure and enhanced the catalytic response by 1.6-fold. The SnO2 NFs-supported GCE/Au NPs/SnO2 NFs composite sensor demonstrated a very good catalytic activity during the reduction of hydrogen peroxide (H2O2) that displayed rapid amperometric behavior within 6.5 s. This sensor allowed for highly sensitive and selective detection. The sensitivity was 14.157 µA/mM, the linear detection range was from 49.98 µM to 3937.21 µM (R2 = 0.99577), and the lower limit of detection was 6.67 µM. Furthermore, the developed sensor exhibited acceptable reproducibility, repeatability, and stability over 41 days. In addition, the Au NPs/SnO2 NFs composite sensor was tested for its ability to detect H2O2 in tap water, apple juice, Lactobacillus plantarum, Bacillus subtilis, and Escherichia coli. Therefore, this sensor would be useful due to its accuracy and sensitivity in detecting contaminants (H2O2) in commercial products. [ABSTRACT FROM AUTHOR]

The use of gold nanoparticles as drug delivery systems has received increasing attention due to their unique properties, such as their high stability and biocompatibility. However, gold nanoparticles have a high affinity for proteins, which can result in their rapid clearance from the body and limited drug loading capabilities. To address these limitations, we coated the gold nanoparticles with silica and PEG, which are known to improve the stability of nanoparticles. The synthesis of the nanoparticles was carried out using a reduction method. The nanoparticles' size, morphology, and drug loading capacity were also studied. The SEM images showed a spherical and homogeneous morphology; they also showed that the coatings increased the average size of the nanoparticles. The results of this study provide insight into the potential of gold nanoparticles coated with silica and PEG as drug delivery systems. We used ibuprofen as a model drug and found that the highest drug load occurred in PEG-coated nanoparticles and then in silica-coated nanoparticles, while the uncoated nanoparticles had a lower drug loading capacity. The coatings were found to significantly improve the stability and drug load properties of the nanoparticles, making them promising candidates for further development as targeted and controlled release drug delivery systems. [ABSTRACT FROM AUTHOR]

Objectives: Gold nanoparticles are very popular metallic nanomaterials and they have a wide spectrum of biomedical applications. This study was aimed to the production of stable and monodisperse polyethyleneimine (PEI) and polyethylene glycol (PEG) coated gold nanoparticles (AuNP20 and AuNP50), investigation of their in vivo biochemical effects in the BALB/c mice. Methods: Gold nanoparticles were synthesized and their surfaces were modified by PEI and PEG. All the necessary physicochemical characterizations were performed. After the single high dose i.v. injection (5 mg Au/kg animal weight) of the AuNP groups, their in vivo biochemical effects were evaluated multiparametrically in the mice on day 14. Results: Highly monodisperse and stable AuNPs were synthesized successfully. Significant changes in the biochemical hemogram parameters were observed depending on the surface coatings of the AuNPs. PEI and PEG surface coatings increased biocompatibility. No excessive oxidative stress response was observed in all the gold nanoparticle groups. Conclusions: It has been concluded that the surface chemistry of the particles is a more decisive parameter than the size in terms of in vivo biochemical toxicity. The surface functionalization, stability and biocompatibility of the AuNPs are important parameters for the potential biomedical applications of gold nanoparticles in future studies. [ABSTRACT FROM AUTHOR]

Introduction: In this study, we aimed to identify the benefits in image contrast enhancement of Folic acid-Cysteamine conjugated gold nanoparticles (FA-Cys-AuNPs) by comparing Contrast to Noise ratio (CNR) of gold nanoparticles (AuNPs) to iodinated compound CT images. The CNR was assessed in different tube voltages, concentrations, and incubation times in nasopharyngeal KB cancer cells. Material and Methods: FA-Cys-AuNPs and Omnipaque suspension were scanned at different concentration ranges (500-2000 µg/ml) and energy ranges (80-140 kVp) with CT imaging modality. FA-Cys-AuNPs and AuNPs were incubated in nasopharyngeal cancer cells at different incubation times (6, 12, and 24 h) and concentration ranges (200-500 µM). Finally, the contrast enhancement was assessed using CNR value at different tube voltages. Results: Results showed that the formed FA-Cys-AuNPs with an Au core size of 15 nm in all concentrations and tube potentials from 80 to 140 kVp display greater CNR than Omnipaque. The CNR value was increased by increasing concentration and energy. At 140 kVp and 2000 µg/ml, the CNR value of FA-Cys-AuNPs was 2.25 times greater than Omnipaque. At 140 kVp, 500 µM and 24 h incubation, the CNR values of targeted cells were approximately 1.5 times higher than non-targeted cells. At 140 kVp, and 500 µM, the CNR value of targeted cells with 24 h incubation time was 2.66 times greater than the targeted cells incubated with 6 h. Conclusion: These findings suggested that the designed FA-Cys-AuNPs could be a good candidate contrast agent for molecular CT imaging. [ABSTRACT FROM AUTHOR]

This study aims to investigate the detection limits of gold nanoparticle (GNP) concentrations by Monte Carlo (MC) modeling of benchtop polychromatic K‐ and L‐shell X‐ray fluorescence mapping system. In Monte Carlo N‐Particle (MCNP version 6.1) simulations, a 0.25‐cm‐diameter cylinder containing GNPs of various concentrations (i.e., 0.005%–1.0% gold by weight, wt%) was assumed to be located at the center of a cylindrical water phantom of various diameters (1.0–10 cm). Two different sets of incident pencil beam X‐rays and detectors were modeled to stimulate X‐ray fluorescence (XRF) of GNPs: (1) 62 kVp and silicon drift detector for L‐XRF, (2) 105 kVp and cadmium telluride detector for K‐XRF. The detection limits were calculated for given radiation doses to the center of phantom (375–1500 mGy). When the diameter of the phantom was 1 cm, the detection limits for L‐XRF and K‐XRF were an order of 0.001 wt% and of 0.01 wt%, respectively. The detectability of K‐XRF turned out to be superior to that of L‐XRF for the phantoms greater than or equal to 3 cm in diameter. The MC results will provide a guide for developing an optimal benchtop XRF imaging system for in vivo preclinical imaging, depending on the sizes of GNP‐loaded objects, GNP concentrations, and radiation doses. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) are well known to interact with cells, leading to different cell behaviors such as cell proliferation and differentiation capacity. Biocompatibility and biological functions enhanced by nanomedicine are the most concerning factors in clinical approaches. In the present research, AuNP solutions were prepared at concentrations of 1.25, 2.5, 5 and 10 ppm for biocompatibility investigations. Ultraviolet–visible spectroscopy was applied to identify the presence of AuNPs under the various concentrations. Dynamic Light Scattering assay was used for the characterization of the size of the AuNPs. The shape of the AuNPs was observed through a Scanning Electron Microscope. Afterward, the mesenchymal stem cells (MSCs) were treated with a differentiation concentration of AuNP solutions in order to measure the biocompatibility of the nanoparticles. Our results demonstrate that AuNPs at 1.25 and 2.5 ppm could significantly enhance MSC proliferation, decrease reactive oxygen species (ROS) generation and attenuate platelet/monocyte activation. Furthermore, the MSC morphology was observed in the presence of filopodia and lamellipodia while being incubated with 1.25 and 2.5 ppm AuNPs, indicating that the adhesion ability was enhanced by the nanoparticles. The expression of matrix metalloproteinase (MMP-2/9) in MSCs was found to be more highly expressed under 1.25 and 2.5 ppm AuNP treatment, relating to better cell migrating ability. Additionally, the cell apoptosis of MSCs investigated with Annexin-V/PI double staining assay and the Fluorescence Activated Cell Sorting (FACS) method demonstrated the lower population of apoptotic cells in 1.25 and 2.5 ppm AuNP treatments, as compared to high concentrations of AuNPs. Additionally, results from a Western blotting assay explored the possibility that the anti-apoptotic proteins Cyclin-D1 and Bcl-2 were remarkably expressed. Meanwhile, real-time PCR analysis demonstrated that the 1.25 and 2.5 ppm AuNP solutions induced a lower expression of inflammatory cytokines (TNF-α, IL-1β, IFN-γ, IL-6 and IL-8). According to the tests performed on an animal model, AuNP 1.25 and 2.5 ppm treatments exhibited the better biocompatibility performance, including anti-inflammation and endothelialization. In brief, 1.25 and 2.5 ppm of AuNP solution was verified to strengthen the biological functions of MSCs, and thus suggests that AuNPs become the biocompatibility nanomedicine for regeneration research. [ABSTRACT FROM AUTHOR]

Irreversible electroporation (IRE) is a non-thermal tumor ablation technique that delivers short pulses of strong electric fields to cancer tissues and induces cell death through the destruction of cell membranes. Here, we synthesized gold-doped mesoporous silica nanoparticles (Au-MSNs) via incipient wetness impregnation and evaluated the therapeutic potentials of combination therapy with IRE. The fabricated Au-MSNs had around 80–100 nm of particle size and were successfully end-doped with Au nanoparticles. Combination treatment of IRE (800 V/cm) and Au-MSNs (100 μg/mL) increased cell membrane permeability by 25-fold compared with single IRE treatment. Cellular reactive oxygen species (ROS) and lipid peroxidation of EMT-6 cells were significantly increased by 14- and 265-fold, respectively, under combination treatment of IRE (800 V/cm) and Au-MSNs (100 µg/mL). Cytotoxic cell death increased by 28% under a combination treatment of IRE (800 V/cm) and Au-MSNs (100 ug/mL) over single IRE. Our studies suggest that the combination treatment of IRE with Au-MSNs can enhance the therapeutic efficacy of IRE for breast cancer. [ABSTRACT FROM AUTHOR]

In this study, there are two objectives had been done. The first involved the fabrication of a white light emitting diode (LED) with a high color rendering index (CRI) through the near-ultraviolet excitation of red, green, and blue phosphors, and the phosphor ratios were adjusted to obtain a color temperature of 2800 K. Due to this LED had relatively low brightness, the addition of gold nanoparticles at various concentrations had been done to enhance light reflection within the LED, thereby improving the light output. The nanoparticle diameters were measured through high-resolution transmission electron microscopy, and the chromaticity coordinates, CRI, luminous flux, and radiation power of the light source were measured using an integrating sphere. Finally, a white LED with a high CRI and a high light intensity was successfully developed. [ABSTRACT FROM AUTHOR]

Lipopolysaccharide (LPS) poses a considerable threat to food safety and human health. A colorimetric assay for LPS detection based on LPS binding aptamer (LBA) and SYBR Green I (SG) mediated aggregation of gold nanoparticles (AuNPs) was established. In the absence of LPS, the LBA was absorbed onto the AuNPs surface which prevented SG-induced aggregation of AuNPs, and the sensing system exhibited red color. When LPS was added, it interacted with the LBA, forming a complex. At higher LPS concentration, many LBAs were exhausted resulting in SG-induced aggregation of AuNPs, and color change from red to blue. The range of colorimetric detection of LPS was linear in 0–12 EU/mL, with a limit of detection of 0.1698 EU/mL. Spiked LPS in real samples and interfering substances were also identified. This assay ingeniously using the fluorescent dye SG as an effective trigger of AuNPs aggregation, is rapid and facile than most of those earlier reported LBA-based LPS assays, and there is potential to be modified to construct assays for other targets. • Simple and fast detection of lipopolysaccharide (LPS) is of great importance. • A colorimetric LPS assay based on aptamer, SYBR Green I and AuNPs was proposed. • Selective detection of LPS with a detection limit of 0.1698 EU/mL was realized. [ABSTRACT FROM AUTHOR]

Metal nanoparticles are effective radiosensitizers that locally enhance radiation doses in targeted cancer cells. Compared with other metal nanoparticles, gold nanoparticles (GNPs) exhibit high biocompatibility, low toxicity, and they increase secondary electron scatter. Herein, we investigated the effects of active-targeting GNPs on the radiation-induced bystander effect (RIBE) in prostate cancer cells. The impact of GNPs on the RIBE presents implications for secondary cancers or spatially fractionated radiotherapy treatments. Anti-prostate-specific membrane antigen (PSMA) antibodies were conjugated with PEGylated GNPs through EDC–NHS chemistry. The media transfer technique was performed to induce the RIBE on the non-irradiated bystander cells. This study focused on the LNCaP cell line, because it can model a wide range of stages relating to prostate cancer progression, including the transition from androgen dependence to castration resistance and bone metastasis. First, LNCaP cells were pretreated with phosphate buffered saline (PBS) or PSMA-targeted GNPs (PGNPs) for 24 h and irradiated with 160 kVp X-rays (0–8 Gy). Following that, the collected culture media were filtered (sterile 0.45 µm polyethersulfone) in order to acquire PBS- and PGNP- conditioned media (CM). Then, PBS- and PGNP-CM were transferred to the bystander cells that were loaded with/without PGNPs. MTT, γ-H2AX, clonogenic assays and reactive oxygen species assessments were performed to compare RIBE responses under different treatments. Compared with 2 Gy-PBS-CM, 8 Gy-PBS-CM demonstrated a much higher RIBE response, thus validating the dose dependence of RIBE in LNCaP cells. Compared with PBS-CM, PGNP-CM exhibited lower cell viability, higher DNA damage, and a smaller survival fraction. In the presence of PBS-CM, bystander cells loaded with PGNPs showed increased cell death compared with cells that did not have PGNPs. These results demonstrate the PGNP-boosted expression and sensitivity of RIBE in prostate cancer cells. [ABSTRACT FROM AUTHOR]

Single domain antibodies (sdAb) are the recombinant variable heavy domains derived from camelid heavy-chain antibodies. While they have binding affinities equivalent to conventional antibodies, sdAb are only one-tenth the size and possess numerous advantages such as excellent thermal stability with the ability to refold following denaturation, and inexpensive production in Escherichia coli or yeast. However, their small size does have drawbacks, one being that they can lose activity upon attachment or adsorption to surfaces, or may fail to adsorb efficiently, as they are highly soluble. This can make the transition from using conventional antibodies to sdAb nontrivial for assay development. Specifically, it is often necessary to re-optimize the protocols and tailor the recombinant sdAb through protein engineering to function efficiently in handheld assays, which currently are utilized for point of care testing and field applications. This work focuses on optimizing the integration of sdAb into rapid vertical flow assays. To achieve this goal, we engineered sdAb-based constructs and developed general protocols for the attachment of the sdAb to both gold nanoparticles and a support membrane. We achieved a limit of detection of 0.11 µg/mL for toxins staphylococcal enterotoxin B and ricin, both potential biothreat agents. Additionally, we demonstrated the ability to detect the nucleocapsid protein of SARS-CoV-2, a common target of antigen tests for COVID-19. [ABSTRACT FROM AUTHOR]

In the study, human serum albumin functionalized gold nanoparticles (HSA-AuNPs) were fabricated benefiting from the unique properties of HSA and AuNP to achieve tamoxifen delivery to breast cancer cells for renewing tumor targeting with unconventional nanoparticles. The release pattern of tamoxifen (TMX), the cell viability, oxidative DNA damage, and total antioxidant capacity of HSA-AuNP with and without TMX were assessed on BT-474 and MDA MB-231 breast cancer cell lines. The outcomes indicated that TMX entrapped HSA-AuNP can induce cancer cell death in a dose-dependent aspect and could be proved via further studies as a potential drug delivery agent. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (GNPs) have immense potential in biomedicine, but understanding their interactions with serum proteins is crucial as it could change their biological profile due to the formation of a protein corona, which could then affect their ultimate biodistribution in the body. Grafting GNPs with polyethylene glycol (PEG) is a widely used practice in research in order to decrease opsonization of the particles by serum proteins and to decrease particle uptake by the mononuclear phagocyte system. We investigated the impact of PEGylation on the formation of protein coronae and the subsequent uptake by macrophages and MDA-MB-231 cancer cells. Furthermore, we investigated the in vivo biodistribution in xenograft tumor-bearing mice using a library of 4 and 10 nm GNPs conjugated with a gadolinium chelate as MRI contrast agent, cancer-targeting aptamer AS1411 (or CRO control oligonucleotide), and with or without PEG molecules of different molecular weight (Mw: 1, 2, and 5 kDa). In vitro results showed that PEG failed to decrease the adsorption of proteins; moreover, the cellular uptake by macrophage cells was contingent on the different configurations of the aptamers and the length of the PEG chain. In vivo biodistribution studies showed that PEG increased the uptake by tumor cells for some GNPs, albeit it did not decrease the uptake of GNPs by macrophage-rich organs. [ABSTRACT FROM AUTHOR]

Nanoparticles can promote the accumulation of drugs in tumors. However, they find limited clinical applications because they cannot easily penetrate the stroma of cancer tissues, and it is difficult to control drug release. We developed a multiresponse multistage drug-delivery nanogel with improved tumor permeability and responsiveness to the tumor microenvironment for the controlled delivery of anticancer agents. For this purpose, ~100 nm multistage drug delivery nanogels with pH, redox, near-infrared stimulation, and enzyme responsiveness were grown in situ using 20 nm gold nanoparticles (AuNPs) via an emulsion-aiding crosslinking technique with cysteine crosslinker. An alginate cysteine AuNP (ACA) nanocarrier can efficiently load the cationic drug doxorubicin (DOX) to produce a multistage drug delivery nanocarrier (DOX@ACA). DOX@ ACA can maintain the slow release of DOX and reduce its toxicity. In cancer tissues, the high pH and reductase microenvironment combined with the in vitro delivery of alginate and near-infrared light drove drug release. The developed nanoparticles effectively inhibited cancer cells, and in vivo evaluations showed that they effectively enhanced antitumor activity while having negligible in vivo toxicity to major organs. [ABSTRACT FROM AUTHOR]

Recently there had been a great interest in biologically synthesized nanoparticles (NPs) as potential therapeutic agents. The shortcomings of conventional non-biological synthesis methods such as generation of toxic byproducts, energy consumptions, and involved cost have shifted the attention towards green syntheses of NPs. Among noble metal NPs, gold nanoparticles (AuNPs) are the most extensively used ones, owing to the unique physicochemical properties. AuNPs have potential therapeutic applications, as those are synthesized with biomolecules as reducing and stabilizing agent(s). The green method of AuNP synthesis is simple, eco-friendly, non-toxic, and cost-effective with the use of renewable energy sources. Among all taxa, cyanobacteria have attracted considerable attention as nano-biofactories, due to cellular uptake of heavy metals from the environment. The cellular bioactive pigments, enzymes, and polysaccharides acted as reducing and coating agents during the process of biosynthesis. However, cyanobacteria-mediated AuNPs have potential biomedical applications, namely, targeted drug delivery, cancer treatment, gene therapy, antimicrobial agent, biosensors, and imaging. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) were synthesized using citrate reduction, also known as the Turkevich method. The AuNPs were compared with the commercially available product and later subjected to characterization. The AuNPs were 13 nm in diameter with a 2.7 × 108 M−1cm−1 extension coefficient. The calculated concentration was 5.1 nM through the Beer–Lambert law using UV–vis absorbance spectra. Further detailed characterization was applied, such as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), elemental analysis using electro and DLS instruments, energy-dispersive X-ray spectroscopy (EDS), XRD, and Zeta potential. The synthesized AuNPs had a higher UV-absorbance peak of 0.93 in comparison to commercially available nanoparticles at 5.8 identical conditions. The characterization confirmed successful fabrication of colloidal-citrate-capped AuNPs and their dispersed and aggregated state with induced salt concentration. The shape and morphology were confirmed through XRD, showing a face-centered cubic lattice of {111}, confirmed at 38.1 round shape, and a crystalline lattice. AuNPs tend to be applied in sensing, detection, drug delivery, pharmaceuticals, and other applications in the environment and materials. Other applications include environmental contaminant detection, colorimetric sensors, antimicrobial applications, biosensing and drug delivery, tissue engineering, nanomedicines, optoelectronics, and catalysts. [ABSTRACT FROM AUTHOR]

Objective: Hypericum perforatum is a herbal medicine used in traditional medicine for the treatment of depression due to its antidepressant and anti-inflammatory activities. Therefore, we evaluated the therapeutic efficacy of H. perforatum extract (HPE) in combination with gold nanoparticles (HPE-GNP) against experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Materials and Methods: EAE was induced in C57BL/6 mice with subcutaneous injection of MOG35-55 emulsified in complete Freund's adjuvant, and intraperitoneal pertussis toxin. Mice were treated with drugs in free (HPE) and nano-form (HPE-GNP) preparations. Splenocytes were isolated from all mice and the level of inflammatory and anti-inflammatory cytokines were evaluated by ELISA. The expression of T cells' transcription factors was also assessed using Real-Time PCR.Results: Clinical score was reduced after HPE-GNP treatment. This change was associated with a decrease in the incidence and infiltration of inflammatory cells into the central nervous system. Additionally, treatment with HPE-GNP decreased the level of pro-inflammatory cytokines (IFN-γ, IL-17A and IL-6) and increased anti-inflammatory cytokines (TGF-β, IL-10 and IL-4). The real-time analysis revealed a decrease in the level of T-bet and ROR-γt but an increase in FoxP3 and GATA3 expression.Conclusion: The current study demonstrated that HPE-GNP could potentially reduce clinical and pathological complications of EAE, but laboratory data showed that HPE-GNP was significantly more effective than HPE in the treatment of EAE.

Objective(s): Several studies reported the apoptotic and lytic activity of melittin (Mel) in different tumor cells. In this study, a novel nano-complex was developed composed of AS1411aptamers, melittin and gold nanoparticle for the treatment of breast cancer cells. Materials and Methods: Gold nanoparticles (GNP) were synthesized using reduction of tetrachloroauric acid (HAuCl4). Melittin modified with cysteine and AS1411aptamer conjugated to the gold nanoparticle. Gel retardation assay was used to prove the formation of GNP-Mel-AS1411 complex. Physicochemical properties of complex were investigated by Dynamic Light Scattering (DLS). The cytotoxicity of Mel and GNP-Mel-AS1411 complex were evaluated in both MCF‐7 (target) and L929 (non-target) cells by the MTT assay. Results: The average size of GNP and GNP-Mel-AS1411 complex were 20 ± 2.5 and 270.5± 3.2 respectively. The results of MTT assay revealed that this nanocomplex was more cytotoxic in MCF‐7 (cell viability = 19% ± 2%) and less cytotoxic in L929 cells (cell viability = 73% ± 1.6%).Conclusion: The results of this study indicated that the gold nanoparticle-melittin-AS1411 complex had a potential value in cancer cell targeted delivery of melittin.

Abstract Background To take advantages, such as multiplex capacity, non-photobleaching property, and high sensitivity, of surface-enhanced Raman scattering (SERS)-based in vivo imaging, development of highly enhanced SERS nanoprobes in near-infrared (NIR) region is needed. A well-controlled morphology and biocompatibility are essential features of NIR SERS nanoprobes. Gold (Au)-assembled nanostructures with controllable nanogaps with highly enhanced SERS signals within multiple hotspots could be a breakthrough. Results Au-assembled silica (SiO2) nanoparticles (NPs) (SiO2@Au@Au NPs) as NIR SERS nanoprobes are synthesized using the seed-mediated growth method. SiO2@Au@Au NPs using six different sizes of Au NPs (SiO2@Au@Au50–SiO2@Au@Au500) were prepared by controlling the concentration of Au precursor in the growth step. The nanogaps between Au NPs on the SiO2 surface could be controlled from 4.16 to 0.98 nm by adjusting the concentration of Au precursor (hence increasing Au NP sizes), which resulted in the formation of effective SERS hotspots. SiO2@Au@Au500 NPs with a 0.98-nm gap showed a high SERS enhancement factor of approximately 3.8 × 106 under 785-nm photoexcitation. SiO2@Au@Au500 nanoprobes showed detectable in vivo SERS signals at a concentration of 16 μg/mL in animal tissue specimen at a depth of 7 mm. SiO2@Au@Au500 NPs with 14 different Raman label compounds exhibited distinct SERS signals upon subcutaneous injection into nude mice. Conclusions SiO2@Au@Au NPs showed high potential for in vivo applications as multiplex nanoprobes with high SERS sensitivity in the NIR region. Graphical Abstract

[Display omitted] • A sensitive and visual biosensor method for metallothionein detection is established. • The assay combines Hg2+-coordinated DNA probe with Cas12a/crRNA amplification. • Detection of metallothionein in fish organs with the developed sensor is demonstrated. The accurate and sensitive detection of metallothionein (MT) is of great significance in the fields of biomedical, toxicological and environmental sciences. In this work, based on the high affinity interaction between MT and the heavy metal ions of Hg2+ and the significant signal amplification capability of Cas12a/crRNA enzyme as well, we report a simple and highly sensitive method for visual detection of MT, a biomarker in fish for heavy metal ion-induced water bio-pollution. The target MT molecules bind Hg2+ in the Hg2+- complexed hairpin DNA probes to unfold the hairpin structure into ssDNAs, which hybridize with the partial dsDNA duplexes via strand displacement to yield specific sequence-containing dsDNAs. Cas12a/crRNA recognizes these specific sequences to activate its enzyme activity to cyclically cleave the ssDNA linkers in the blue colored gold nanoparticle aggregates to transit their color into red to realize visual detection of MT. Owing to the signal amplification by Cas12a/crRNA, as low as 25 nM of MT can be visually detected with naked eye. In addition, our colorimetric detection method has high selectivity for MT against other interference proteins and can detect MT in the livers and kidneys of crucian carps bought from a local supermarket. Moreover, the developed assay overcomes the limitations of conventional MT detection methods in terms of complexity, high cost and low sensitivity and can therefore offer new methods for monitoring water bio-pollutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Divalent ions (Mg2+, Ca2+) attract gold nanoparticles more strongly than monovalent ions (Na+, K+). • Magnesium ions interact with gold nanoparticles about six times more intensely than sodium ions. • Ion concentration and interactions significantly affect ion mobility and hydration. This study provides a comprehensive analysis of the interactions between negatively charged gold nanoparticles (Au) 144 (SRCOO1−) 60 and both divalent (Mg2+, Ca2+) and monovalent (Na+, K+) ions in aqueous solution, employing molecular dynamics simulations. The investigation focuses on elucidating the energetics, hydrogen bond patterns and radial distribution of ions surrounding gold nanoparticles. Our results reveal distinct differences in the Coulombic and van der Waals energies between gold nanoparticles and ions, as well as between gold nanoparticles and water, which exert influence on hydrogen bond patterns and lifetimes, as even as ion and water mobility. These findings have important implications for potential applications in nanotechnology and materials science. This research contributes to a deeper understanding of ion-nanoparticle interactions and provides valuable insights for the design and development of new nanomaterials with properties and functionalities. [ABSTRACT FROM AUTHOR]

In response to the growing demand for biomolecular diagnostics, metasurface (MS) platforms based on high-Q resonators have demonstrated their capability to detect analytes with smart data processing and image analysis technologies. However, high-Q resonator meta-atom arrays are highly sensitive to the fabrication process and chemical surface functionalization. Thus, spectrum scanning systems are required to monitor the resonant wavelength changes at every step, from fabrication to practical sensing. In this study, we propose an innovative dielectric resonator-independent MS platform that enables spectrometer-less biomolecule detection using artificial intelligence (AI) at a visible wavelength. Functionalizing the focused vortex MS to capture gold nanoparticle (AuNP)-based sandwich immunoassays causes the resulting vortex beam profiles to be significantly affected by the localized surface plasmon resonance (LSPR) occurring between AuNPs and meta-atoms. The convolutional neural network algorithm was carefully trained to accurately classify the AuNP concentration-dependent focused vortex beam, facilitating the determination of the concentration of the targeted diagnostic biomolecule. Successful in situ identification of various biomolecule concentrations was achieved with over 99 % accuracy, indicating the potential of combining an LSPR-susceptible MS platform and AI for continuously tracking various chemical and biological compounds. [Display omitted] • A dielectric resonator-independent and localized surface plasmon resonance-susceptible metasurface platform. • Diverse vortex beam patterns generation due to the localized surface plasmon resonance of gold nanoparticles on meta-atoms. • Determination of the concentration of targeted diagnostic molecules assisted by artificial intelligence. [ABSTRACT FROM AUTHOR]

• DiODA cultivates fewer deviations from its regular all-trans conformer than ODA. • DiODA passivation shows more intra- and intermolecular order than ODA passivation. • Pure diODA molecules show much less trans-gauche [CH 3 -CH 2 -] end-defects than ODA. This work reveals that diOctadecylamine (diODA) outperforms its primary amine counterpart ODA in intra- and intermolecular order, forming passivation monolayers on 5 nm small gold nanoparticles. We support this conclusion by meticulously analyzing the differences in the Fourier Transform Infrared (FTIR) spectrum of diODA and ODA molecules in their pure- and coordinated-to-gold-nanoparticle phases. Detailed diODA spectral data are scarce in the literature and are absent for diODA-passivated nanoparticles, whose merits have gone unnoticed. The analysis compares the signatures of defects and all indicators for molecular packing in the ligand. The results align with the High-Resolution Transmission Electron Microscopy (HR-TEM) based analysis. We observe unexpectedly that pure diODA molecules are not prone to form trans-gauche (TG) [CH 3 -CH 2 -gauche] end-conformation. At the same time, an intensive absorption structure at the relevant TG position around 760 cm−1 indicates its presence in pure ODA. The spectrum of pure ODA indicates higher energy of the internal kink defects in the vicinity of 1306 cm−1 than pure diODA. In the coordinated phase, both molecules reduce their initial energy. However, the observed better-pronounced red shift of the structures reveals a crystal-like chain arrangement for diODA. Consequently, the HR-TEM images reveal a spontaneous formation of 2D arrangement only for diODA passivated nanoparticles having nearly twice as large gold core separation as the one provided by ODA molecules. The present analysis can be used as a preliminary test in demanding applications where tightly packed coatings of nanoparticles with impenetrable organic passivation are essential. [ABSTRACT FROM AUTHOR]

This study investigates the behaviour of gold nanoparticles (AuNPs) when exposed to chlorpyrifos, an agricultural pesticide, and its application in detecting the pesticide via surface-enhanced Raman spectroscopy (SERS). Under synergistic addition of NaCl, AuNPs undergo agglomeration at lower chlorpyrifos concentrations but aggregation at higher concentrations, resulting in a distinctive nonlinear SERS response. A linear relationship is obtained between 0.001 and 1 ppm with detection limit (LOD) of 0.009 ppm, while an inverse response is observed at higher concentrations (1–1000 ppm) with a LOD of 1 ppm. Combining the colorimetric response of AuNP solutions, their absorbance spectra, and principal component analysis can improve detection reliability. The assay, coupled with a simple recovery method using acetonitrile swabbing, achieves high reproducibility in detecting chlorpyrifos in cucumber, even at concentrations as low as 0.11 ppm. This approach can be tailored for various chlorpyrifos concentrations not only in cucumbers but also in different food matrices. [Display omitted] • With NaCl, AuNPs agglomerate at low and aggregate at high chlorpyrifos concentrations. • Optimized assay exhibits linear relationship from 10−3-1 ppm, inversely correlated at 1–103 ppm. • Simple acetonitrile swabbing achieves high reproducible chlorpyrifos detection in cucumber. • Combining AuNP colour change, absorbance spectra, and PCA enhances detection reliability. [ABSTRACT FROM AUTHOR]

We have conducted a new comparison of gold nanoparticles functionalized by primary- and secondary amine with the same chain length. Our hypothesis suggests that the adaptive steric conformation of the secondary amine molecular branches makes a marked additional contribution to the well-established role of the ligand chain length. We characterize the importance of this factor based on diOctadecylamine (diODA) and Octadecylamine (ODA) passivated gold nanoparticles by using high-resolution transmission electron microscopy (HR-TEM) and selective area electron diffraction (SAED). The results evidenced that the diODA coordination to the inorganic core forms a more efficient and impenetrable protective coating. The SAED patterns show a more homogeneous distribution of the small crystalline domains in the gold core. TEM images show a smooth spherical shape of the diODA nanoparticles and a lack of interparticle coalescence cases. The diODA-passivation provides nanoparticles with nearly twice the effective ligand length than its ODA equivalent. This results in their spontaneous arrangement in domains with expressed crystal-like order despite the relatively large size-dispersity before passivation. The surface free energy of coatings, formed by diODA passivated gold nanoparticles, is twice as small as measured on the ODA-nanoparticle-coated surfaces. [Display omitted] • DiOctadecylamine- compared to Octadecylamine-capped gold nanoparticles: • Formed more efficient protective monolayers. • Resulted in more homogeneous gold core crystalline domains. • Results in a superior effective ligand length and tends to self-arrange regularly. • Formed hydrophobic coatings with twice lower surface free energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • C. trachomatis infection accounts for the majority of all sexually transmitted infections. • The effective prevention, treatment, and laboratory diagnosis of this type of infection are very important in human society. • The use of nanotechnology science and gold nanoparticle-based methods for the rapid detection of C. trachomatis infection is a new approach in laboratory. Chlamydia trachomatis infections greatly affect people's quality of life and significantly contribute to the prevalence of sexually transmitted diseases. These infections are especially common in low-income countries and regions, such as the Middle East, Asia, Africa, and South America. The World Health Organization (WHO) acknowledges that C. trachomatis is a major global health concern, with a staggering 128.5 million new cases reported among adults in 2020. Consequently, it is vital to establish efficient laboratory diagnostic methods for this infection. However, the existing diagnostic techniques have limitations, emphasizing the necessity for new, rapid diagnostic platforms that can swiftly identify this pathogen with great accuracy, without the need for skilled technicians or significant expenses. One promising approach for addressing these challenges is the utilization of nanotechnology and gold nanoparticle-based methods to rapidly detect C. trachomatis infection. In this systematic review, our objective is to evaluate the latest advancements in utilizing gold nanoparticle-based methods for laboratory detection of C. trachomatis. We conducted a comprehensive search of biomedical databases and collected all relevant manuscripts published from 2010 to 2023. This review presents newly developed methods for detecting C. trachomatis infection using gold nanoparticles. Also, we discusses the advantages and disadvantages of these methods, as shown in recent studies, and compares them to other approaches using different parameters. [ABSTRACT FROM AUTHOR]

Lactose, or milk sugar, is one of the essential carbohydrates included in the human diet. Its most significant source is milk and other dairy products. Still, due to the ever-increasing percentage of the population with lactose intolerance, there is a need to detect and quantify it in food products. Surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) method on gold nanoparticle enhanced steel target (AuNPET) was used to rapidly detect and quantify lactose with a minimum sample pretreatment including molecular weight cut-off ultrafiltration. The carbohydrate was tested directly in the concentration range from 500 µg/mL to 1 µg/mL, which corresponds to 1.46 nmol to 2.92 pmol per analyzed spot. Limit of detection (LOD) of 0.14 µg/mL or 0.42 µM is one of the best among the techniques used to determine lactose. In addition, the quantitative approach based on mass spectrometry of milk samples shown in this study made it possible to decide on lactose concentration in real samples. • Lactose was tested directly on SALDI AuNPs target in the concentration range from 500 µg/mL to 1 µg/mL. • SALDI MS made it possible to achieve an LOD value of 0.14 µg/mL with linearity from 1 to 25 µg/mL. • The achieved LOD value is one of the best among analytical methods used for lactose determination. • SALDI MS based on AuNPs allowed detection of lactose in both pure solutions and milk samples. • AuNPs-SALDI MS allowed quantification of lactose in milk samples with a minimum sample pretreatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • We report one way for synthesis of Chinese tower-like nanogold using glutathione as chiral inducer. • The formed nanogold offers excellent catalytic activity due to full exposure of high-index faces. • The introduction of graphene quantum dot induce production of viscous Ti 3 C 2 T X -nanogold hydrogel. • Proposed electrochemical method for fipronil shows superhigh sensitivity and selectivity. The current electrochemical methods cannot meet the requirements of sensitivity, specificity and stability for detection of pesticides in vegetable and fruit. The paper reports an electrochemical method for detection of fipronil integrating Ti 3 C 2 T X -Chinese tower-like nanogold (CT-Au) with DNA tetrahedron (T-DNA) and catalytic hairpin assembly. Firstly, CT-Au was synthesized by formation, growth of trioctahedron gold nanocrystal and subsequent structural evolution in L-glutathione. Then, it was combined with Ti 3 C 2 T X to form Ti 3 C 2 T X -CT-Au hydrogel via self-assembly of Ti 3 C 2 T X nanosheets induced by arginine-functionalized graphene quantum dot. The resulting Ti 3 C 2 T X -CT-Au film offers good catalytic activity owing to more exposure of high-index faces, conductivity and mechanical property owing to the existence of three-dimensional Ti 3 C 2 T X network. The modified electrode with Ti 3 C 2 T X -CT-Au was developed for electrochemical detection of fipronil, coupling with T-DNA and DNA cycle. In the presence of fipronil, fipronil triggers the DNA cycle and results in the immobilization of ferrocene molecules on the electrode surface, producing a significant signal amplification. Differential pulse voltammetry current linearly increases with increasing fipronil between 1 × 10−18 and 1 × 10−13 M with detection limit of 4.3 × 10−19 M (S/N = 3). The proposed analytical method exhibits outstanding sensitivity, selectivity and reproducibility. It has been satisfactorily applied in electrochemical detection of fipronil in vegetable and fruit. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) can be described as nanozymes, species that are able to mimic the catalytic activities of several enzymes, such as oxidase/peroxidase, reductase, or catalase. Most studies in the literature focus on the colloidal suspension of AuNPs, and it is obvious that their immobilization could open the doors to new applications thanks to their increased stability in this state. This work aimed to investigate the behavior of surfaces covered by immobilized AuNPs (iAuNPs). Citrate-stabilized AuNPs (AuNPs-cit) were synthesized and immobilized on glass slides using a simple dip coating method. The resulting iAuNPs were characterized (surface plasmon resonance, microscopy, quantification of immobilized AuNPs), and their multi-enzymatic-like activities (oxidase-, peroxidase-, and catalase-like activity) were evaluated. The comparison of their activities versus AuNPs-cit highlighted their added value, especially the preservation of their activity in some reaction media, and their ease of reuse. The huge potential of iAuNPs for heterogeneous catalysis was then applied to the degradation of two model molecules of hospital pollutants: metronidazole and methylene blue.

Gold nanoparticles (Au NPs) have become one of the building blocks for superior assembly and device fabrication due to the intrinsic, tunable physical properties of nanoparticles. With the development of DNA nanotechnology, gold nanoparticles are organized in a highly precise and controllable way under the mediation of DNA, achieving programmability and specificity unmatched by other ligands. The successful construction of abundant gold nanoparticle assembly structures has also given rise to the fabrication of a wide range of sensors, which has greatly contributed to the development of the sensing field. In this review, we focus on the progress in the DNA-mediated assembly of Au NPs and their application in sensing in the past five years. Firstly, we highlight the strategies used for the orderly organization of Au NPs with DNA. Then, we describe the DNA-based assembly of Au NPs for sensing applications and representative research therein. Finally, we summarize the advantages of DNA nanotechnology in assembling complex Au NPs and outline the challenges and limitations in constructing complex gold nanoparticle assembly structures with tailored functionalities.

The development of sensor technology enables the creation of DNA-based biosensors for biomedical applications. Herein, a quartz tuning fork (QTF) sensing system was employed as a transducer for biomedical applications to address indirect DNA damage associated with gold nanoparticles (GNPs) and enhance the effectiveness of low-dose gamma radiation in radiation therapy. The experiment included two stages, namely during and after irradiation exposure; shift frequencies (Δf) were measured for 20 min in each stage. During the irradiation stage, the QTF response to DNA damage was investigated in a deionized aqueous solution with and without 100 nm GNPs at different concentrations (5, 10, 15, and 20 µg/mL). Upon exposure to gamma radiation for 20 min at a dose rate of 2.4 µGy/min, the ratio of Δf/ΔT indicates increased fork displacement frequencies with or without GNPs. Additionally, DNA damage associated with high and low GNP concentrations was evaluated using the change in the resonance frequency of the QTF. The results indicate that GNPs at 15 and 10 µg/mL were associated with high damage-enhancement ratios, while saturation occurred at 20 µg/mL. At 15 µg/mL, significant radiotherapy enhancement occurred compared to that at 10 µg/mL at 10 min after exposure. In the post-irradiation stage, the frequency considerably differed between 15 and 10 µg/mL. Finally, these results significantly depart from the experimental predictions in the post-radiation stage. They exhibited no appreciable direct effect on DNA repair owing to the absence of an environment that promotes DNA repair following irradiation. However, these findings demonstrate the potential of enhancing damage by combining GNP-mediated radiation sensitization and biosensor technology. Thus, QTF is recommended as a reliable measure of DNA damage to investigate the dose enhancement effect at various GNP concentrations.

Since contact lenses directly contact the cornea, the surface roughness of the lens may cause various side effects. In addition, gold nanoparticles can realize a variety of colors and characteristics depending on their shape and size. In this study, the surface roughness of tinted lenses containing gold nanoparticles of various sizes was analyzed using atomic force microscopy (AFM) at aspect ratio(surface to volume ratio) ranging from 1:1 to 1:10. The characteristics of the lenses were then confirmed. As a result, tinted lenses with different colors depending on the size of the gold nanoparticles were manufactured. The surface roughness of the lens decreased with increasing size of the gold nanoparticles. However, at aspect ratio of 1:10, increase in surface roughness was observed. In addition, it was confirmed that the wettability and antibacterial properties of the lens had the same effect according to the average surface roughness value. Therefore, it was confirmed that the addition of gold nanoparticles reduced the surface roughness of the lens, which had a great effect on properties such as wettability and antimicrobial properties of the lens. The produced copolymer controls the surface roughness of the lens, and thus it is judged that it can be used as a material for various ophthalmology applications.

The COVID-19 pandemic has underscored the critical need for virus detection methods that are precise, simple, quick, and cost-effective. Electrochemical immunoassay-based methods are a practical solution given their ability to quickly, inexpensively, sensitively, and selectively detect the virus at the point of care. This study details the immunomagnetic capture of SARS-CoV-2 nucleocapsid protein in nasal samples, followed by electrochemical detection using gold nanoparticle labels on a screen-printed carbon electrode. We determined ideal conditions for the size of the gold nanoparticles and the length of the deposition time to maximize the electrochemical signal. The limit of detection for nucleocapsid protein was determined to be 2.64 ng/mL in PBS. The assay was successfully demonstrated to detect nucleocapsid protein in SARS-CoV-2-positive samples with a viral load as low as Ct = 25 (p-value < 0.0001 vs. negative patient control).

The co-assembly of block copolymers (BCPs) and inorganic nanoparticles (NPs) under emulsion confinement allows facile access to hybrid polymeric colloids with controlled hierarchical structures. Here, the effect of inorganic NPs on the structure of the hybrid BCP particles and the local distribution of NPs are studied, with a particular focus on comparing Au and Fe3O4 NPs. To focus on the effect of the NP core, Au and Fe3O4 NPs stabilized with oleyl ligands were synthesized, having a comparable diameter and grafting density. The confined co-assembly of symmetric polystyrene-b-poly(1,4-butadiene) (PS-b-PB) BCPs and NPs in evaporative emulsions resulted in particles with various morphologies including striped ellipsoids, onion-like particles, and their intermediates. The major difference in PS-b-PB/Au and PS-b-PB/Fe3O4 particles was found in the distribution of NPs inside the particles that affected the overall particle morphology. Au NPs were selectively localized inside PB domains with random distributions regardless of the particle morphology. Above the critical volume fraction, however, Au NPs induced the morphological transition of onion-like particles into ellipsoids by acting as an NP surfactant. For PS-b-PB/Fe3O4 ellipsoids, Fe3O4 NPs clustered and segregated to the particle/surrounding interface of the ellipsoids even at a low volume fraction, while Fe3O4 NPs were selectively localized in the middle of PB domains in a string-like pattern for PS-b-PB/Fe3O4 onion-like particles.