Search Results (227)

FLASH radiotherapy, which delivers radiation at ultrahigh dose rates (UHDRs) exceeding 40 Gy/s, has attracted considerable attention because of its potential to spare normal tissues while maintaining tumour control. Gold nanoparticles (GNPs) are promising radiosensitizers that enhance radiation-induced biological effects through increased production of reactive oxygen species (ROS) and subsequent DNA damage. However, the influence of GNPs on DNA damage under FLASH irradiation remains poorly understood. In this study, Geant4-DNA Monte Carlo simulations were performed to investigate the effects of GNP size and dose rate on DNA damage during UHDR electron-beam irradiation. DNA damage was quantified through both direct and indirect mechanisms based on energy deposition in DNA backbone segments and interactions between radiation-induced radical species and DNA, and was evaluated relative to equivalent water nanoparticle (WNP) controls. The results demonstrated a dose rate-dependent reduction in both relative single-strand breaks (RSSBs) and relative double-strand breaks (RDSBs) arising from direct and indirect DNA damage mechanisms. For the 10 keV monoenergetic model condition, the 10 nm GNP produced the greatest radiosensitization among the particle sizes investigated, with the matched GNP/WNP analysis showing a maximum 5-fold enhancement in direct SSB yields. In contrast, substantially weaker GNP-specific enhancement and no comparable size-dependent effect were observed at 1 MeV. These findings demonstrate that GNP-mediated radiosensitization depends on both nanoparticle size and electron energy under the irradiation conditions investigated. The greater enhancement observed for the 10 nm GNP at 10 keV should therefore not be interpreted as identifying a universally optimal GNP size for FLASH radiotherapy. Full article

Background/Objectives: Human adenoviruses (HAdVs) are widely used as vectors for vaccines and gene therapy; however, pre-existing immunity can reduce their efficacy. Therefore, rapid and accessible serological methods are required to assess antibody levels against adenoviruses. Lateral flow immunochromatographic assay (LFIA) sensitivity depends on the label and antigen. In this study, we aimed to develop and evaluate LFIA systems based on gold nanoparticles (GNPs) and quantum dots (QDs) using a recombinant HAdV hexon protein. Methods: A recombinant HAdV hexon protein fragment (rhHAdV, 35 kDa; amino acids A120-R316) was expressed in Escherichia coli and purified using Ni²⁺ affinity chromatography. Protein identity was confirmed using sodium dodecyl sulfate–polyacrylamide gel electrophoresis, Western blotting, and liquid chromatography–tandem mass spectrometry analyses. Two LFIA formats were developed using Protein G-conjugated GNPs (GNP-G) and QDs (QD-G). Agreement with the reference ELISA was evaluated using 90 human serum samples. Results: The rhHAdV antigen demonstrated reactivity with anti-adenovirus-positive human sera in ELISA. Antibody detection was achieved at serum dilutions of up to 1:300 and 1:1000 for the GNP- and QD-based LFIA, respectively. The GNP-G and QD-G LFIA formats demonstrated positive percent agreements of 96.9% and 100%, respectively, while both assays showed a negative percent agreement of 98.2% compared with the reference ELISA. Conclusions: The findings demonstrate the feasibility of a QD-based LFIA for qualitative detection of antibodies reactive with the recombinant HAdV-B3 hexon fragment. Full article

The unique physicochemical properties of gold nanoparticles (GNPs) have made them versatile tools for biomedical applications, such as imaging, therapy, and drug delivery. The surface modification of GNPs with polymers or biomolecules can enhance their colloidal stability and facilitate internalization into cells. However, the efficient and biocompatible delivery to the central nervous system remains a major challenge, as many existing nanocarriers show poor capacity to cross the blood-brain barrier. We developed a method to coat GNPs with linear polyethyleneimine (GNP@PEI) through a chemical reduction bottom-up approach, in which linear PEI hydrochloride acts simultaneously as a reducing and stabilizing agent of colloidal dispersion. This strategy yielded monodisperse spherical GNP@PEI nanoparticles with an average diameter of 50 nm. The physicochemical profile, biocompatibility, and capacity for neural uptake of this potentially brain-targeted nanoplatform were then evaluated. GNP@PEI nanoparticles exhibited high biocompatibility in several primary neural cultures and cell lines, with cellular uptake showing clear cell-type-dependent differences. In vivo studies carried out in a murine model demonstrated that after the intranasal or intraperitoneal administrations of GNP@PEI nanoparticles, detectable levels of gold were found in several organs, including the brain. Collectively, these findings highlight the potential of GNP@PEI as a promising nanoplatform for brain-targeted delivery and for advancing the development of therapeutic strategies for neurological disorders. Full article

A lateral flow immunoassay (LFIA) utilizing two types of marker conjugates—magnetite nanoparticles (MNPs) with specific antibodies and gold nanoparticles (GNPs) with anti-species antibodies—was proposed and realized for the detection of the pesticide paraquat. In this assay, the MP conjugate is used to concentrate the target analyte from the tested sample and then to form labeled immune complexes at the test strip, while the GNP conjugate is then applied for the integration into the formed complexes in the binding zone. The magnetic preconcentration allows for working with large volumes of samples, and the following treatment by the GNP conjugate enhances the coloration by five times for reliable analyte revelation in lower concentrations. In the course of the assay implementation, its conditions have been optimized, and the efficiency of the paraquat determination in orange samples was confirmed. The achieved detection limits were 1.2–3.7 ng/mL for visual assessment and 0.12–0.48 ng/mL for the instrumental one, with paraquat detection rates ranging from 96% to 120%. The implementation of the assay in combination with the stage of magnetic concentration allows for the collection of paraquat from large volumes of samples and detects it in this way in concentrations up to two orders of magnitude smaller. Full article

Background: Gold nanoparticles (GNPs) are widely used in nanomedicine as drug carriers, including in targeted radionuclide therapy where therapeutic radionuclides are bound to GNPs. Quantitative assessment of their biodistribution is essential. X-ray fluorescence imaging (XFI) is well suited for detecting high-Z elements, but its quantitative accuracy is compromised by strong attenuation effects, particularly in L-shell XFI where low-energy fluorescence (~10 to 12 keV) is heavily absorbed in tissue. Methods: We developed a computed tomography (CT)-guided attenuation correction algorithm for L-shell XFI. The method generates energy-dependent attenuation maps from co-registered CT data and performs voxel-wise corrections along both excitation and emission paths. The approach was tested on an ex vivo murine tumor sample resected three hours after intratumoral injection of 34.7 μg PEG-modified GNPs. Results: Application of the CT-guided correction substantially improved the relative accuracy of L-shell XFI reconstructions compared to uncorrected data. The corrected distribution maps showed consistent mass recovery across different measurement geometries, demonstrating that the algorithm compensates for the theoretically expected attenuation due to heterogeneous biological tissue. Conclusions: This study provides a proof-of-principle that CT-based attenuation correction enables more reliable and quantitative L-shell XFI of GNPs in biological samples. The approach represents a promising step toward accurate nanoparticle biodistribution assessment in biomedical research, including preclinical studies in targeted radionuclide therapy. Full article

Listeria monocytogenes is a major foodborne pathogen associated with increasing global public health concern due to numerous outbreaks. Rapid pathogen detection is critical for reducing both the incidence and severity of foodborne illnesses. Recent advances in nanotechnology are transforming analytical methods, particularly for detecting foodborne pathogens. Magnetic nanoparticles (MNPs) and gold nanoparticles (GNPs) are among the most widely used nanomaterials in this field. This study investigated the potential use of MNPs and GNPs for the rapid and specific isolation of L. monocytogenes from fresh salad, deli meat, and frozen vegetables. L. monocytogenes (ATCC 19117) served as the model organism for biosensing and target capture. Results showed that the limits of detection (LoDs) for the GNP-based plasmonic/colorimetric biosensor and the MNP-based biosensor were 2.5 ng/µL DNA and 1.5 CFU/mL, respectively. Both GNPs and MNPs specifically detected L. monocytogenes even in the presence of closely related pathogens. Integration of MNPs and GNPs significantly enhanced the sensitivity of L. monocytogenes detection. Within one hour, naturally contaminated pre-packaged salad samples demonstrated clear evidence of effective direct capture by MNPs and specific identification by GNPs. This combined approach enables rapid and accurate on-site detection of L. monocytogenes, facilitating timely intervention and reducing the risk of contaminated foods reaching consumers. Full article

Cancer treatments are limited by poor tumor specificity and toxicity. We tested a radiosensitizing approach using PEG/RGD-functionalized gold nanoparticles (GNPs), a lipid-nanoparticle–encapsulated docetaxel prodrug (LNP_DTX–P), and external-beam radiotherapy (RT). In MIA PaCa-2 xenografts, intravenous GNPs (2 mg/kg) and LNP_DTX–P (6 mg/kg) were given before 5 Gy RT. Both LNP_DTX–P + RT and GNPs + LNP_DTX–P + RT reduced tumor volume by ~40% and significantly prolonged survival versus RT alone (p < 0.001). Adding GNPs did not enhance efficacy, indicating LNP_DTX–P was the main driver under this regimen. These results demonstrate nanocarrier-enabled radiosensitization in vivo and support further studies toward clinical translation. Full article

Nanoparticles (NPs) of noble metals such as gold have garnered significant attention due to their novel optical and catalytic properties, their theranostic properties, as they are biocompatible, and they attract considerable interest in a range of applications including targeted drug delivery. In this study, a fractional factorial design (FFD) is applied to systematically investigate the influence of key synthesis parameters (independent variables) at a low level (−1) and a high level (+1), including the reducing agent type (chitosan or trisodium citrate), concentration of reducing agent (10 to 40 mg), pH (3.5 to 8.5), temperature (60 to 100 °C), agitation time (5 to 15 min), and agitation speed (400 to 1200 rpm), on the dependent parameters—particle size and polydispersity index of gold nanoparticles (GNPs). The goal of this study was to provide a comprehensive understanding of the interplay between these parameters and their interaction effect on the characteristics of gold nanoparticles. A fractional factorial design allowed for efficient screening of the parameter space while minimizing the number of experiments required. The results demonstrated that pH, reducing agent, reducing agent–concentration, reducing agent–concentration of reducing agent–pH, and reducing agent–temperature interactions played significant roles in determining the particle size of the synthesized GNPs. Moreover, pH and reducing agent–concentration were identified as the major factors influencing the dispersity of the NPs. This study sheds light on the complex relationships between synthesis parameters and NP characteristics, offering an insight into the capacity for optimizing the synthesis process in order to tailor the desired properties of GNPs. The findings contribute to the growing field of NP synthesis and advance the understanding of the underlying mechanisms governing the formation of GNPs with specific size and dispersity characteristics. Full article

Lateral flow immunoassays (LFAs) are widely recognized as a powerful and versatile analytical platform. Nevertheless, the development of multiplex formats remains a distinct challenge. The aim of this study was to develop a multiplex LFA using gold nanoparticles (GNPs) as a label, selected for their ease of synthesis and functionalization with biomolecules. We provide practical recommendations regarding protein–hapten synthesis, membrane selection, application buffer composition, and methods to improve the long-term stability of the freeze-dried gold conjugate. The developed assay shows good tolerance to high-fat milk, stability at elevated temperatures, and promising sensitivity, with visual detection limits of 4–100 ng/mL for $\beta$-lactams, 1–10 ng/mL for tetracyclines, 50 ng/mL for streptomycin, and 0.3 ng/mL for chloramphenicol. Full article

Ultrahigh dose rate (UHDR) radiotherapy, also known as FLASH radiotherapy (FLASH-RT), has shown potential for increasing tumor control while sparing normal tissue. In parallel, gold nanoparticles (GNPs) have been extensively explored as radiosensitizers due to their high atomic number and ability to enhance the generation of reactive oxygen species (ROS) through water radiolysis. In this study, we investigate the synergistic effects of UHDR electron beams and GNP-mediated radiosensitization using Monte Carlo (MC) simulations based on the Geant4-DNA code. A spherical water phantom with embedded GNPs of varying sizes (5–100 nm) was irradiated using pulsed electron beams (100 keV and 1 MeV) at dose rates of 60, 100, and 150 Gy/s. The chemical yield of ROS near the GNPs was quantified and compared to an equivalent water nanoparticle model, and the yield enhancement factor (YEF) was used to evaluate radiosensitization. Results demonstrated that YEF increased with smaller GNP sizes and at lower UHDR, particularly for 1 MeV electrons. A maximum YEF of 1.25 was observed at 30 nm from the GNP surface for 5 nm particles at 60 Gy/s. The elevated ROS concentration near GNPs under FLASH conditions is expected to intensify DNA damage, especially double-strand breaks, due to increased hydroxyl radical interactions within nanometric distances of critical biomolecular targets. These findings highlight the significance of nanoparticle size and beam parameters in optimizing ROS production for FLASH-RT. The results provide a computational basis for future experimental investigations into the combined use of GNPs and UHDR beams in nanoparticle-enhanced radiotherapy. Full article

Background: Gold nanoparticles (GNPs) are increasingly studied for their potential to enhance wound healing, but their overall efficacy remains uncertain. Methods: We conducted a systematic meta-analysis (search date: 14 May 2025) across five databases. Included were randomized animal studies comparing GNPs to placebo, reporting wound closure percentages and relevant variance measures. Risk of bias was assessed using Cochrane and CAMARADES tools. Cohen’s d was used to estimate effect size under a random-effects model. Results: Thirty-one studies met the inclusion criteria. The pooled effect size was d = 4.52 (95% CI: 3.61 to 5.43; z = 9.73; p < 0.001), indicating a significant benefit of GNPs. Although heterogeneity was moderate to high, results consistently favored GNPs. Conclusion: GNPs significantly accelerate wound healing in animal models, supporting their potential as therapeutic agents. Full article

Objectives: In this research study, we introduce a novel approach to develop an innovative nanocarrier system comprising gold nanoparticles (GNPs) loaded with doxorubicin (D) in combination with natural molecules, such as trans-resveratrol (R), piperine (P), and icariin (Ic), against human cervical cancer. The final objective is to improve the anticancer efficacy of doxorubicin on HeLa and CaSki cell lines. Methods: Resveratrol was also used for the synthesis of GNP_R1 nanoparticles. Multi-functional GNPs loaded with D, R, P, and Ic (e.g., GNP_R1@D/R/P/Ic) were successfully prepared and fully characterized by SPR, TEM, HR-TEM, XRD, AFM, DLS, and zeta potential. They were investigated for in vitro stability in various biological media. The cytotoxicity activity was tested on HeLa and CaSki cell lines, using the MTT assay, for their applications as anticancer agents. Results: Our results demonstrate that the novel multi-functional GNPs (such as GNP_R1@D/R and GNP_R1@D/R/P/Ic) can effectively target the cervical cancer cells, improving the bioavailability of therapeutic agents and enhancing their cytotoxicity against cervical cancer cells. In vitro assessments demonstrated that the multi-functional GNPs exhibited improved stability and potential anticancer efficacy on human cervical cancer cells. Conclusions: The described strategy connects the benefits of biomolecules with functional nanoparticles toward the development of various GNP_R1@D/R/P/Ic nanocarriers for their applications as anticancer agents against human cervical cancer. This study provides compelling evidence that the innovative nanoparticles can enhance the therapeutic efficacy of doxorubicin against cervical cancer and offer a more advantageous alternative compared to doxorubicin monotherapy. Full article

Multivalent lectin–glycan interactions (MLGIs) are vital for viral infection, cell-cell communication and regulation of immune responses. Their structural and biophysical data are thus important, not only for providing insights into their underlying mechanisms but also for designing potent glycoconjugate therapeutics against target MLGIs. However, such information remains to be limited for some important MLGIs, significantly restricting the research progress. We have recently demonstrated that functional nanoparticles, including ∼4 nm quantum dots and varying sized gold nanoparticles (GNPs), densely glycosylated with various natural mono- and oligo- saccharides, are powerful biophysical probes for MLGIs. Using two important viral receptors, DC-SIGN and DC-SIGNR (together denoted as DC-SIGN/R hereafter), as model multimeric lectins, we have shown that α-mannose and α-manno-α-1,2-biose (abbreviated as Man and DiMan, respectively) coated GNPs not only can provide sensitive measurement of MLGI affinities but also reveal critical structural information (e.g., binding site orientation and mode) which are important for MLGI targeting. In this study, we produced mannuronic acid (ManA) coated GNPs (GNP-ManA) of two different sizes to probe the effect of glycan modification on their MLGI affinity and antiviral property. Using our recently developed GNP fluorescence quenching assay, we find that GNP-ManA binds effectively to both DC-SIGN/R and increasing the size of GNP significantly enhances their MLGI affinity. Consistent with this, increasing the GNP size also significantly enhances their ability to block DC-SIGN/R-augmented virus entry into host cells. Particularly, ManA coated 13 nm GNP potently block Ebola virus glycoprotein-driven entry into DC-SIGN/R-expressing cells with sub-nM levels of EC₅₀. Our findings suggest that GNP-ManA probes can act as a useful tool to quantify the characteristics of MLGIs, where increasing the GNP scaffold size substantially enhances their MLGI affinity and antiviral potency. Full article

Background/Objectives: Bacterial infections remain among the top ten major public health concerns, contributing to a high number of incidences of disease and mortality worldwide, exacerbated by the rise of multidrug-resistant bacteria (MDRB). Consequently, it is crucial to develop novel antimicrobial strategies, including the use of functional nanoparticles. Gold nanoparticles (GNPs) have emerged as promising candidates due to their unique optical properties, particularly their ability to efficiently convert absorbed light into heat through the photothermal (PT) effect, which can be harnessed for bacteria eradication. Methods: Chitosan was modified with 3-mercaptopropionic acid to introduce sulfur groups, facilitating gold deposition onto chitosan nanoparticle (TCNPs) surface. The gold shell was subsequently formed via a seed-mediated method, wherein gold seeds were adsorbed onto TCNPs and further grown to form the shell. Photothermal effect on the bacterial viability was evaluated. Results: TCNPs with a size of 178 nm and spherical morphology were obtained. After the gold shell (TCNP@Au) exhibited a photothermal conversion efficiency of 31%, making them a promising photothermal agent for bacterial clearance. Notably, the viability of Escherichia coli was significantly reduced in the presence of TCNP@Au and was almost eradicated upon PT treatment. In contrast, TCNP@Aus were non-toxic for Staphylococcus aureus. Conclusions: TCNP@Au demonstrated favorable photothermal properties, presenting a novel nanoplatform for antibacterial applications, particularly against Gram-negative bacteria. However, further investigation is required to optimize the PT-based strategies against Gram-positive bacteria, such as S. aureus. Full article

Gold nanomaterials have garnered significant attention in biomedicine owing to their tunable size and morphology, facile surface modification capabilities, and distinctive optical properties. The surface functionalization of these nanoparticles can enhance their safety and efficacy in nanomedical applications. In this study, we examined the biological effects of gold nanoparticles (GNPs) with three distinct surface modifications (polyethylene glycol, chitosan, and polyethylenimine) in murine models, elucidating their mechanisms of action on hepatic tissue at both the transcriptomic and metabolomic levels. Our findings revealed that PEG-modified GNPs did not significantly alter any major metabolic pathway. In contrast, CS-GNPs markedly affected the metabolic pathways of retinol, arachidonic acid, linoleic acid, and glycerophospholipids (FDR < 0.05). Similarly, PEI-GNPs significantly influenced the metabolic pathways of retinol, arachidonic acid, linoleic acid, and sphingolipids (FDR < 0.05). Through a comprehensive analysis of the regulatory information within these pathways, we identified phosphatidylcholine compounds as potential biomarkers that may underlie the differential biological effects of the three functionalized GNPs. These findings provide valuable experimental data for evaluating the biological safety of functionalized GNPs. Full article