Search

Hydrogen peroxide (H2O2) plays critical roles innumerous biological process, including cell proliferation, differentiation, and apoptosis; oxidative stress and cancer cells related metabolic activities. But its accurate detection remains challenging. This [...]

Silicon-based nanoparticles (SiNPs) have been investigated for their applications in a wide variety of cell labeling with low toxicity and biocompatibility. However, SiNPs are frequently reported to have a strong [...]

Metal-containing nanoparticles are now common in applications ranging from catalysts to biomarkers. However, little research has focused on per-particle metal content in multicomponent nanoparticles. In this work, we used single-particle inductively coupled plasma mass spectrometry (ICP-MS) to determine the per-particle metal content of silica nanoparticles doped with tris(2,2′-bipyridyl)ruthenium(II). Monodispersed silica nanoparticles with varied Ru doping levels were prepared using a water-in-oil microemulsion method. These nanoparticles were characterized using common bulk-sample methods such as absorbance spectroscopy and conventional ICP-MS, and also with single-particle ICP-MS. The results showed that averaged concentrations of metal dopant measured per-particle by single-particle ICP-MS were consistent with the bulk-sample methods over a wide range of dopant levels. However, the per-particle amount of metal varied greatly and did not adhere to the usual Gaussian distribution encountered with one-component nanoparticles, such as gold or silver. Instead, the amount of metal dopant per silica particle showed an unexpected geometric distribution regardless of the prepared doping levels. The results indicate that an unusual metal dispersal mechanism is taking place during the microemulsion synthesis, and they challenge a common assumption that doped silica nanoparticles have the same metal content as the average measured by bulk-sample methods. [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiNPs) have been used as vehicles for drug delivery, molecular detection, and cellular manipulations in nanoneuromedicine. SiNPs may cause adverse effects in the brain including neurotoxicity, neuroinflammation, neurodegeneration, and enhancing levels of amyloid beta (A[beta]) protein--all pathological hallmarks of Alzheimer's disease. Therefore, the extent to which SiNPs influence A[beta] generation and the underlying mechanisms by which this occurs deserve investigation. Our studies were focused on the effects of SiNPs on endolysosomes which uptake, traffic, and mediate the actions of SiNPs. These organelles are also where amyloidogenesis largely originates. We found that SiNPs, in primary cultured hippocampal neurons, accumulated in endolysosomes and caused a rapid and persistent deacidification of endolysosomes. SiNPs significantly reduced endolysosome calcium stores as indicated by a significant reduction in the ability of the lysosomotropic agent glycyl-L-phenylalanine 2-naphthylamide (GPN) to release calcium from endolysosomes. SiNPs increased Ap1-40 secretion, whereas 2 agents that acidified endolysosomes, ML-SA1 and CGS21680, blocked SiNP-induced deacidification and increased generation of Ap1-40. Our findings suggest that SiNP-induced deacidification of and calcium release from endolysosomes might be mechanistically linked to increased amyloidogenesis. The use of SiNPs might not be the best nanomaterial for therapeutic strategies against Alzheimer's disease and other neurological disorders linked to endolysosome dysfunction. Key words: Alzheimer's disease, amyloid beta protein, endolysosomes, nanoparticles, ML-SA1, silica nanoparticles, SiNP. Les nanoparticules de silice (ou SiNP pour << silica nanoparticles >>) ont ete utilisees en nanoneuromedecine comme vehicule en vue du largage de medicaments, de la detection moleculaire et de la manipulation cellulaire. Par contre, les SiNP pourraient entrainer des effets indesirables dans le cerveau, notamment de la neurotoxicite, de la neuroinflammation, de la neurodegenerescence, ainsi que l'augmentation des taux de la proteine beta amyloide (A[beta]) : toutes des caracteristiques de la maladie d'Alzheimer. Par consequent, l'etendue de l'influence des SiNP sur la production d'Ap et les modes d'action sous-jacents meritent d'etre etudies. Nos etudes etaient centrees sur les effets des SiNP sur les endolysosomes, lesquels recueillent les SiNP, les font circuler et participent a la mediation de leurs effets. Ces organites sont aussi largement a la base de l'amyloidogenese. Dans des cultures de neurones de l'hippocampe primitifs, nous avons observe que les SiNP s'accumulent dans les endolysosomes et y entrainent une desacidification rapide et persistante. Les SiNP entrainaient une diminution importante des stocks de calcium dans les endolysosomes dont temoignait une diminution notable de la capacite du GPN (glycyl-L-phenylalanine 2-naphthylamide), un agent lysosomotrope, d'en liberer du calcium. Les SiNP entrainaient une augmentation de la secretion de l'Ap1-40 alors que le ML-SA1 et le CGS21680, deux agents qui entrainaient une acidification des endolysosomes, permettaient d'inhiber la desacidification et l'augmentation de la production d'Ap1-40 engendrees par les SiNP. Nos resultats laissent entendre que les modes d'action de la desacidification et de la liberation du calcium des endolysosomes engendrees par les SiNP pourraient etre lies a une augmentation de l'amyloidogenese. En somme, les SiNP pourraient ne pas etre les meilleurs nanomateriaux a utiliser dans des strategies visant le traitement de la maladie d'Alzheimer ou d'autres maladies neurologiques liees au dysfonctionnement des endolysosomes. [Traduit par la Redaction] Mots-cles : maladie d'Alzheimer, proteine amyloide beta, endolysosomes, nanoparticules, ML-SA1, nanoparticules de silice, SiNP., Introduction The discovery of silica nanoparticles (SiNPs) has led, in part, to the growth of nanotechnology in various fields including electronics, aerospace engineering, health care, and biomedicine (Singh et al. [...]

Recently, nano-based cancer therapeutics have been researched and developed, with some nanomaterials showing anticancer properties. When it comes to cancer treatment, graphene quantum dots (GQDs) contain the ability to generate 1O2, a reactive oxidative species (ROS), allowing for the synergistic imaging and photodynamic therapy (PDT) of cancer. However, due to their small particle size, GQDs struggle to remain in the target area for long periods of time in addition to being poor drug carriers. To address this limitation of GQDs, hollow mesoporous silica nanoparticles (hMSNs) have been extensively researched for drug delivery applications. This project investigates the utilization and combination of biomass-derived GQDs and Stöber silica hMSNs to make graphene quantum dots-hollow mesoporous silica nanoparticles (GQDs-hMSNs) for fluorescent imaging and dual treatment of cancer via drug delivery and photodynamic therapy (PDT). Although the addition of hMSNs made the newly synthesized nanoparticles slightly more toxic at higher concentrations, the GQDs-hMSNs displayed excellent drug delivery using fluorescein (FITC) as a mock drug, and PDT treatment by using the GQDs as a photosensitizer (PS). Additionally, the GQDs retained their fluorescence through the surface binding to hMSNs, allowing them to still be used for cell-labeling applications. [ABSTRACT FROM AUTHOR]

The advancing field of nanoscience has produced lower mass, smaller size, and expanded chemical composition nanoparticles over recent years. These new nanoparticles have challenged traditional analytical methods of qualification and quantification. Such advancements in nanoparticles and nanomaterials have captured the attention of toxicologists with concerns regarding the environment and human health impacts. Given that nanoparticles are only limited by size (1–100 nm), their chemical and physical characteristics can drastically change and thus alter their overall nanotoxicity in unpredictable ways. A significant limitation to the development of nanomaterials is that traditional regulatory and scientific methods used to assess the biological and environmental toxicity of chemicals do not generally apply to the assessment of nanomaterials. Significant research effort has been initiated, but much more is still needed to develop new and improved analytical measurement methods for detecting and quantitating nanomaterials in biological and environmental systems. [ABSTRACT FROM AUTHOR]

An ultrasensitive and versatile assay for biomarkers has been developed using graphene/gold nanoparticles (AuNPs) composites and single-particle inductively-coupled plasma/mass spectrometry (spICP-MS). Thrombin was chosen as a model biomarker for this study. AuNPs modified with thrombin aptamers were first non-selectively adsorbed onto the surface of graphene oxide (GO) to form GO/AuNPs composites. In the presence of thrombin, the AuNPs desorbed from the GO/AuNPs composites due to a conformation change of the thrombin aptamer after binding with thrombin. The desorbed AuNPs were proportional to the concentration of thrombin and could be quantified by spICP-MS. By counting the individual AuNPs in the spICP-MS measurement, the concentration of thrombin could be determined. This assay achieved an ultralow detection limit of 4.5 fM with a broad linear range from 10 fM to 100 pM. The method also showed excellent selectivity and reproducibility when a complex protein matrix was evaluated. Furthermore, the diversity and ready availability of ssDNA ligands make this method a versatile new technique for ultrasensitive detection of a wide variety of biomarkers in clinical diagnostics. [ABSTRACT FROM AUTHOR]

An ultrasensitive assay is described for the detection and determination of Hg2+(aq) in water samples based on single-particle inductively-coupled plasma/mass spectrometry (spICP-MS). In the presence of Hg2+(aq), AuNPs modified with a segment of single-stranded DNA aggregate due to the formation of the well-known thymine (T)-Hg2+-T complex. Single particle (sp) ICP-MS is used quantify the degree of aggregation by the overall decrease in number of detected AuNPs or NP aggregates. Compared with most other Hg2+ assays that use the same principle of aggregation-dispersion with DNA modified AuNPs, this method has a much lower detection limit of (0.031 ng L−1, 155 fM) and a wider (10,000-fold) linear range (up to 1 μg L−1). The method also showed good practical potential because of its minimal interference from the water sample matrix. [ABSTRACT FROM AUTHOR]

The 3′–5′ exonuclease enzyme plays a dominant role in multiple pivotal physiological activities, such as DNA replication and repair processes. In this study, we designed a sensitive graphene oxide (GO)-based probe for the detection of exonuclease enzymatic activity. In the absence of Exo III, the strong π–π interaction between the fluorophore-tagged DNA and GO causes the efficient fluorescence quenching via a fluorescence resonance energy transfer (FRET). In contrast, in the presence of Exo III, the fluorophore-tagged 3′-hydroxyl termini of the DNA probe was digested by Exo III to set the fluorophore free from adsorption when GO was introduced, causing an inefficient fluorescence quenching. As a result, the fluorescence intensity of the sensor was found to be proportional to the concentration of Exo III; towards the detection of Exo III, this simple GO-based probe demonstrated a highly sensitive and selective linear response in the low detection range from 0.01 U mL−1 to 0.5 U mL−1 and with the limit of detection (LOD) of 0.001 U mL−1. Compared with other fluorescent probes, this assay exhibited superior sensitivity and selectivity in both buffer and fetal bovine serum samples, in addition to being cost effective and having a simple setup. [ABSTRACT FROM AUTHOR]

G-quadruplex/hemin (G/H) complex has been broadly used in bioanalytical chemistry for the peroxidase-mimicking application. The property of G/H complex makes it possible to catalyze the decomposition of H2O2. The hydroxyl radical (OH) generated during the procedure has a higher antibacterial performance than the original H2O2. Herein, an efficient and biocompatible antibacterial system, which provides the same antibacterial efficiency at lower H2O2 concentration to alleviate the H2O2 toxicity, has been demonstrated based on the conversion of H2O2 to OH. With adding G/H complex as the additive, the antibacterial activity of H2O2 vastly enhanced against both Gram-positive and Gram-negative bacteria in vitro experiment. Furthermore, the designed antibacterial system was also applied on the mice wound model in vivo and showed outstanding antibacterial activity to prevent wound infection and facilitate wound healing., Yuqian Xing * (G1), Qinqin Pu (2), Xiao Liu (1), Min Wu (2), and Julia Xiaojun Zhao (1) (1) Chemistry, Department of Biomedical Sciences, University of North Dakota, Grand Forks, [...]

Engineered nanoparticles are now used in many industrial fields and consumer products but challenges persist in the rapid and simultaneous characterization of their elemental composition along with concentration, size, and size distribution at a very low concentration. To address these challenges, we have applied the technique of single particle inductively coupled plasma-mass spectrometry (sp-ICP-MS) and demonstrated high level of performance. The technique uses a traditional ICP-MS to perform a particle-by-particle analysis with high sensitivity and isotopic specificity. In this study, we used National Institute of Standards and Technology (NIST)-certified gold nanoparticles (Au-NPs) with different diameters (10, 30, and 60 nm) to validate that our sp-ICP-MS system for both sensitive and selective nanomaterial characterization. In addition to validating the certified size and particle concentration characteristics of the Au-NP reference materials, we confirmed our sp-ICP-MS measurements with transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results of this study indicate that our sp-ICP-MS system works well for the Au-NPs with different diameters, and the particle size observed by sp-ICP-MS corresponded to TEM observation. Furthermore, the particle size and particle concentration can be simultaneously measured in the mixture of 50 [micro]g/L, 60 nm Au-NPs and 10 [micro]g/L, 30 nm Au-NPs., Juan Han * (G), Yuqiang Wang, Julia Xiaojun Zhao, and David T Pierce Department of Chemistry, University of North Dakota, Grand Forks, ND Support: This work was supported by ND-INBRE [...]

HISTORY The Proceedings of the North Dakota Academy of Science (NDAS) was first published in 1948, with Volume 1 reporting the business and scientific papers presented for the 40th Annual [...]

One of the major challenges associated with modeling the influence of the cellular microenvironment on cell growth and differentiation is finding suitable substrates for growing the cells in a manner that recapitulates the cell-cell and cell-microenvironmental interactions in vitro. As one approach to address the challenge, we have developed graphene oxide (GO) 3D scaffold with tunable hardness and porosity for application in cell culture systems. The synthetic method of GO 3D scaffold is simple, easily reproducible and low cost, which is combination of poly(ethylene)(glycol) (PEG) with GO together with a salt leaching approach (NaCl) with a controlled application of heat during the synthetic process to tailor the mechanical properties, porosity and pore size distribution of the resulting GO 3D scaffold. Varying the ratio of NaCl to GO controls porosity, pore size, and pore connectivity for the GO 3D mesh. When the porosity is less than 90%, with an increasing ratio of NaCl to GO, the number of pores increases with good interconnectivity. A qualitative comparison of the pores on the surface image of the 3D scaffold with the pores in cross section confirms that the interior pores appear bigger and more interconnected in the interior of the scaffold. The GO 3D mesh generated with this approach provides an ideal scaffold that can be modified and optimized for a variety of in vitro applications with a range of cells types., Ying Zhang * (P1), Karen Xiao Liu (1), Kayla Michelson (2), Eric Schepp (1), Yuqian Xing (1), Diane Darland (2), and Julia Xiaojun Zhao (1) (1) Chemistry, University of North [...]

Cancer has been considered as one of the most intimidating problems in human life. To fight with various cancers, multiple functional therapies have been developed and the cooperative consequence is not only the simple addition. Graphene based materials such as graphene oxide, reduced graphene oxide have great potential to serve as photothermal therapy agents. In this project, bifunctional cancer treatment system was designed to contain a core of reduced graphene oxide, a shell of mesoporous silica, and an outmost layer of double strand DNAs for a combination of photothermal and chemo-therapy. The doxorubicin was loaded in the silica layer. In a remote control manner, the nanoparticles were irradiated by a near infrared laser to cause the reduced graphene oxide releasing the heat, which leads to the dsDNAs despiralization. Thus, the drug was driven to the outside of the nanoparticles through the pores. This drug delivery system showed low drug release at physiological pH and higher release under acidic conditions. In vitro study, the bifunctional nanoparticles prove to be low toxicity to the cancer cells and normal cells. The data proved its great potential in new cancer therapy., Karen Xiao Liu * (G), Xuefei Zhang, Yuqian Xing, Ying Zhang, and Julia Xiaojun Zhao Chemistry Department, UND Support: This work was supported by North Dakota Department of Commerce, Research [...]

Rapid, efficient and accurate nucleic acid molecule detection is important in the screening of diseases and pathogens, yet remains a limiting factor at point of care (POC) treatment. Microfluidic systems are characterized by fast, integrated, miniaturized features which provide an effective platform for qualitative and quantitative detection of nucleic acid molecules. The nucleic acid detection process mainly includes sample preparation and target molecule amplification. Given the advancements in theoretical research and technological innovations to date, nucleic acid extraction and amplification integrated with microfluidic systems has advanced rapidly. The primary goal of this review is to outline current approaches used for nucleic acid detection in the context of microfluidic systems. The secondary goal is to identify new approaches that will help shape future trends at the intersection of nucleic acid detection and microfluidics, particularly with regard to increasing disease and pathogen detection for improved diagnosis and treatment. [ABSTRACT FROM AUTHOR]

A facile bottom-up method for the synthesis of highly fluorescent graphene quantum dots (GQDs) has been developed using a one-step pyrolysis of a natural amino acid, L-glutamic acid, with the [...]

A facial bottom-up method for the synthesis of fluorescent graphene quantum dots (GQDs) was developed by one-step pyrolysis of glutamic acid. The GQDs showed relatively strong blue, green and red photoluminescent (PL) under the irradiation of ultra-violet, blue and green light, respectively. Interestingly, the GQDs emit NIR fluorescence in the range of 800-850 nm with the excitation dependent manner. The quantum yield of GQDs in the blue range was 66.7% when they were irradiated at 360 nm. And the quantum yield of GQDs when they were irradiated at 780 nm was 1.6%, which demonstrated the upconversion fluorescence properties. For both the regular fluorescence and upconversion fluorescence of GQDs, they both showed the well-known excitation-dependent PL behavior. Furthermore, the feasibility of using for the fluorescence in vivo imaging in mice was investigated, which showed their potential in the bioimaging applications because of their great biocompatibility and low cytotoxicity. In addition, the GQDs show the intrinsic peroxidase-like catalytic activity, which is similar to graphene sheet and carbon nanotubes. Coupled with ABTS, the GQDs can be used for the detection of hydrogen peroxide with the limit of detection of 20 [micro]M., Xu Wu *, Julia Xiaojun Zhao Department of Chemistry, University of North Dakota, Grand Forks, ND, [...]

Surface enhanced fluorescence (SEF) is an important topic in medical and microscopy imaging. Increasing fluorescence efficiency leads to better medical imaging with fewer fluorescence materials needed. Nano-scale objects lend their [...]

Metal nanoshells are of great interests, especially gold nanoshells, due to their tunable optical resonances, inertness in biological medium, good biocompatibility, and ready bioconjugation. In this study, we described the [...]

A novel ultrasensitive, molecular beacon (MB) based sensing system for the mercury ion ([Hg.sup.2+]) was developed. In the design, the assistant probe is introduced into the hybridization buffer containing MB. [...]

We have developed a simple and sensitive DNA sensor utilizing DNA amplification (autonomous DNA machine) and gold nanoparticles (AuNPs). As low as 1 pM of target DNA was detected using [...]

Mercury is a very toxic element, which may cause severe healthy problems even at a very low concentration (the maximum allowable level of mercury in drinking water is 2 ppb). [...]

A number of fluorescent nanoparticles (NPs) have been used as fluorescent labeling materials for bioanalysis. The biological targets include tissues, living cells, DNAs and protein molecules. As more extensive usages [...]

The mechanisms of metal-enhanced fluorescence have been extensively studied and applied to many areas, including bioanalysis. However, in spite of these well developed mechanisms, the rapid development of nanotechnology has [...]

Gold nanorods (AuNRs) have become an important type of metallic nanomaterial in recent years. As labeling nanomaterials, AuNRs have been used in a wide variety of biological applications. In this [...]

The need for sensitive determinations of trace amount of analytes has driven a rapid development of various novel nanomaterials. The photoactive nanomaterials is one of the most promising signaling reagents [...]