Accumulation Of AuNPs Research Articles

Laser-textured hybrid Tin-gold SERS platforms for ultra-trace analyte detection from contaminants

In this study, we report the ultra-trace analyte detection from the complex mixtures of contaminants employing hybrid Sn–Au SERS substrates composed of AuNPs deposited on textured Sn substrates fabricated through a laser-ablation synthesis strategy. The hierarchically arranged sharp micro-pyramids with densely decorated micro/nano-surface features were obtained under the optimized fabrication parameters and depicted the highest SERS performance due to the accumulation of AuNPs within nanoscale inter-particle gaps. The versatility of the synthesized hybrid SERS substrates was explored utilizing a wide category of analytes, including organic dyes (MB and DTTCI), explosives (AN and PA), and biomolecules (adenine and l-tryptophan) exhibiting highly reproducible (relative standard deviation < 10%) SERS signals with the limit-of-detection (LOD) down to 0.32 pM, 3.2 fM, 0.37 μM, 2.93 nM, 0.26 nM, and 0.14 μM concentrations, respectively. Furthermore, the developed SERS sensors were tested for the trace-level identification of specific analytes from the interfering signals of background contaminant species. The two-plex simultaneous detection of AN and adenine molecules exhibit one-order higher LOD 1.25 μM and 1.21 nM, respectively, from the interfering fixed MB concentration. We also demonstrate sensitive identification of thiram and RhB molecules from the complex mixtures of real matrices such as apple juice and chili powder with high detection sensitivity. With Sn-TAu substrates, the well-defined SERS features of thiram and RhB molecules from real matrices exhibit >80% overall intensity compared to pure analytes, along with nano-molar detectability.

An Artificial Miniaturized Peroxidase for Signal Amplification in Lateral Flow Immunoassays.

Signal amplification strategies are widely used for improving the sensitivity of lateral flow immunoassays (LFiAs). Herein, the artificial miniaturized peroxidase Fe(III)-MimochromeVI*a (FeMC6*a), immobilized on gold nanoparticles (AuNPs), is used as a strategy to obtain catalytic signal amplification in sandwich immunoassays on lateral flow strips. The assay scheme uses AuNPs decorated with the mini-peroxidase FeMC6*a and anti-human-IgG as a detection antibody (dAb), for the detection of human-IgG, as a model analyte. Recognition of the analyte by the capture and detection antibodies is first evidenced by the appearance of a red color in the test line (TL), due to the accumulation of AuNPs. Subsequent addition of 3,3',5,5'-tetramethylbenzidine (TMB) induces an increase of the test line color, due to the TMB being converted into an insoluble colored product, catalyzed by FeMC6*a. This work shows that FeMC6*a acts as an efficient catalyst in paper, increasing the sensitivity of an LFiA up to four times with respect to a conventional LFiA. Furthermore, FeMC6*a achieves lower limits of detection that are found in control experiments where it is replaced with horseradish peroxidase (HRP), its natural counterpart. This study represents a significant proof-of-concept for the development of more sensitive LFiAs, for different analytes, based on properly designed artificial metalloenzymes.

99mTc-labeled keratin gold-nanoparticles in a nephron-like microfluidic chip for photo-thermal therapy applications

Biocompatible gold nanoparticles (AuNPs) are particularly interesting for photo-thermal therapy (PTT) of cancer treatment because of their ability to convert light into heating efficiently. Nevertheless, the random accumulation of AuNPs in tissues, mainly determined by their retention time in the bloodstream, is one of the main limiting factors for their use in PTT applications. For this reason, efficient targeting and monitoring of AuNPs in the selected tissues is of paramount importance. This manuscript reports on a new generation of 99mTc-labeled AuNPs coated with keratin (Ker-AuNPs) and their spatial localization investigated by nuclear imaging techniques on an animal-free model. The effective radiolabeling of Ker-AuNPs with 99mTc is achieved using the chelating agent diethylenetriaminepentaacetic acid (DTPA), resulting in the 99mTc-DTPA-Ker-AuNPs nanoconjugate. The 99mTc-DTPA-Ker-AuNPs display a radiochemical purity of 90.7% and excellent photo-thermal properties. In addition, the biocompatibility of the 99mTc-DTPA-Ker-AuNPs with healthy human embryonic kidney (HEK293T) cells is shown. A Lab-On-a-Chip (LoC) approach is used to localize and study the stability of 99mTc-DTPA-Ker-AuNPs under dynamic conditions. To this end, the nanoconjugates are injected into a polydimethylsiloxane microfluidic chip mimicking the renal filtering unit, the nephron, and monitored via radio-imaging and thermo-optical experiments. These detailed studies establish that DTPA-assisted 99mTc-labeled Ker-AuNPs are excellent candidates as biocompatible and non-invasive radiolabeled nanotherapeutic for PTT-based applications.

Nanoparticle-Driven Controllable Mitochondrial Regulation through Lysosome-Mitochondria Interactome.

Precise subcellular manipulation remains challenging in quantitative biological studies. After target modification and hierarchical assembly, nanoparticles can be functionalized for intracellular investigation. However, it remains unclear whether nanoparticles themselves can progressively manipulate subcellular processes, especially organellar networks. Mitochondria act as the energetic supply, whose fission dynamics are often modulated by molecular reagents. Here, using different-sized gold nanoparticles (AuNPs) as a model, we demonstrated the nanoparticle-driven controllable regulation on mitochondria. Compared with molecular reagents, AuNPs could induce size-dependent mitochondrial fission without detectable cell injury, and this process was reversible along with intracellular AuNPs' clearance. Mechanistically, it was attributed to the AuNPs-induced enhanced organelle interactome between lysosomes and mitochondria. Lysosomal accumulation of AuNPs induced lysosomal swelling and lysosomal motility alterations, promoting mitochondrial fission through the increased "kiss" events during the "kiss-and-run" moving of the lysosome-mitochondria interactome. This study highlights the fundamental understanding to fully explore the intrinsic capability of nanoparticles by engineering their basic properties. Also, it provides practical guidance to investigate the delicate nanolevel regulation on biological processes.

Proximity hybridization induced rolling circle amplification for label-free SERS detection of the depression marker human apolipoprotein A4

A new label-free method was developed for SERS detection of human apolipoprotein A4. Rolling circle amplification (RCA) was used, which could induce the production of AuNPs (poly adenine and adsorption gold nanoparticles). When there were two DNA labeled antibodies and target protein, MB1 (molecular beacon 1) was unfolded and the substrate was modified in the homogeneous solution, and the proximate complex was formed. The unfolded molecular beacon worked as a primer in the hybridization with the RCA template to start RCA, which could produce many long sequences of DNA containing amounts of adenines. The AuNPs were bound with the long-repeated adenine in the RCA product, causing accumulation of AuNPs on the surface of the electrode. It was indicated that the spectral characteristics of adenine at 736 cm−1 strongly dominated the SERS spectrum of DNA. Adenine worked as an internal marker for detecting human apolipoprotein A4 by using label-free SERS method. When the conditions were optimal, the detection of human apolipoprotein A4 was carried out from 10 pg mL−1 to 1000 ng mL−1, and the detection limit was low (4.1 pg mL−1). Meanwhile, the specificity was also excellent because the antibody could specifically bind with the corresponding antigen. In addition, since adenine was dominant in SERS spectra and the affinity between AuNPs and poly adenine was high, the detection procedure could be performed without any sophisticated modification. This method might provide a promising strategy for diagnosis in clinical practice.

Photothermal and Photodynamic Therapy of Tumors with Plasmonic Nanoparticles: Challenges and Prospects.

Cancer remains one of the leading causes of death in the world. For a number of neoplasms, the efficiency of conventional chemo- and radiation therapies is insufficient because of drug resistance and marked toxicity. Plasmonic photothermal therapy (PPT) using local hyperthermia induced by gold nanoparticles (AuNPs) has recently been extensively explored in tumor treatment. However, despite attractive promises, the current PPT status is limited by laboratory experiments, academic papers, and only a few preclinical studies. Unfortunately, most nanoformulations still share a similar fate: great laboratory promises and fair preclinical trials. This review discusses the current challenges and prospects of plasmonic nanomedicine based on PPT and photodynamic therapy (PDT). We start with consideration of the fundamental principles underlying plasmonic properties of AuNPs to tune their plasmon resonance for the desired NIR-I, NIR-2, and SWIR optical windows. The basic principles for simulation of optical cross-sections and plasmonic heating under CW and pulsed irradiation are discussed. Then, we consider the state-of-the-art methods for wet chemical synthesis of the most popular PPPT AuNPs such as silica/gold nanoshells, Au nanostars, nanorods, and nanocages. The photothermal efficiencies of these nanoparticles are compared, and their applications to current nanomedicine are shortly discussed. In a separate section, we discuss the fabrication of gold and other nanoparticles by the pulsed laser ablation in liquid method. The second part of the review is devoted to our recent experimental results on laser-activated interaction of AuNPs with tumor and healthy tissues and current achievements of other research groups in this application area. The unresolved issues of PPT are the significant accumulation of AuNPs in the organs of the mononuclear phagocyte system, causing potential toxic effects of nanoparticles, and the possibility of tumor recurrence due to the presence of survived tumor cells. The prospective ways of solving these problems are discussed, including developing combined antitumor therapy based on combined PPT and PDT. In the conclusion section, we summarize the most urgent needs of current PPT-based nanomedicine.

Does repeated gold-nanoparticles administration affect pars distalis hormonal and folliculo-stellate cells in adult male albino rats?

Worldwide, nanoparticles especially gold-nanoparticles (Au-NPs) are widely used in medicine, cancer treatment and cosmetic industry. They are easily conjugated with different biomedical and biological agents and effortlessly absorbed with few side effects. The pars distalis of the pituitary gland is considered as the maestro of the endocrine peripheral glands since it secrets trophic hormones that controls their functions. 5-10% of the non-granular pars distalis cells are folliculo-stellate cells (FSCs) that support the granular cells' functions. The aim of the study was to explore the histological and the biochemical effects of repeated exposure to Au-NPs on the pars distalis in adult male albino rats with highlighting the impact on FSCs. Thirty-six adult male albino rats were divided equally into control group and Au-NPs group (received 40 μg/kg/day of 11 ± 2 nm spherical Au-NPs orally for 2 weeks). Then, rats were euthanized and deposition of Au-NPs in pars distalis was investigated. Biochemical investigations and histological studies including hematoxylin and eosin staining, periodic acid Schiff's reaction, immunohistochemistry (IHC) for S-100, connexin 43 (Cx43) and Cytochrome-C (Cyt-C) as well as electron-microscopic and morphometric studies were carried out. The Au-NPs group demonstrated structural disorganization in the pars distalis, inflammation, congestion and increased extracellular PAS-positive colloid deposition due to the accumulation of Au-NPs. A significant increase in the immunoreactivity of S-100, Cx43 and Cyt-c, along with a significant increase in TNF-a, MDA, and bFGF content in the pituitary homogenates, was noted as compared to the control group. Ultrastructurally, degenerative changes were observed in the secretory cells. FSCs showed proliferation and increased phagocytic activity. Repetitive exposure of adult male albino rats to Au-NPs prompted the accumulation of these nanoparticles in the pars distalis that was accompanied by cellular degeneration and dysfunction of the secretory cell and proliferation of FSCs. Thus, monitoring of the pars distalis hormonal levels might be useful for early detection of some hazardous effects possibly associated with the use of gold-nanoparticles.

Heterogenous Internalization of Nanoparticles at Ultra-Trace Concentration in Environmental Individual Unicellular Organisms Unveiled by Single-Cell Mass Cytometry.

The application and consumption of nanoparticles (NPs) inevitably result in the contamination of environmental water. The internalized NPs in unicellular organisms could travel to human bodies along food chains and raise health concerns. Current research failed to determine the characteristics of cellular uptake of NPs by unicellular organisms at extremely low concentration in the real environment. We here developed a label-free high-throughput mass cytometry method to investigate gold NP (AuNP) uptake in a unicellular organism (Tetrahymena thermophila) at the single-cell level. The limit of detection for Au is as low as to 6.67 × 10-18 g/cell, which equals ∼5.3 5 nm AuNPs. We demonstrated that active engulfment pathways were responsible for the cellular accumulation of AuNPs and T. thermophila could also eliminate the cellular AuNPs rapidly. The interaction between AuNPs and T. thermophila is highly dependent on the sizes of nanoparticles; i.e., the population of T. thermophila containing AuNPs decreased with the increment of the diameters of AuNPs when exposed to the same mass concentration. For each type of AuNP, distinct heterogeneous cellular uptake of AuNPs by T. thermophila was observed. Intriguingly, for 5 nm AuNP, even at 0.001 ng/mL, some T. thermophila cells could concentrate AuNPs, indicating a real environmental concern even when water was contaminated by only trace level of NPs. This method represents a promising tool for simultaneous determination of physiological status of cells together with the intracellular level of heavy metal or metallic NPs in study of biological effects.

Function of gold nanoparticles in oral cancer beyond drug delivery: Implications in cell apoptosis

Gold nanoparticles (AuNPs) are used to deliver drugs and therapeutic small molecule inhibitors to cancer cells. Evidence shows that AuNPs coated with nuclear localization sequence can cross the nuclear membrane and induce cellular apoptosis. To determine the therapeutic role of AuNPs, we compared two nanoconstructs conjugated to doxorubicin (DOX) through pH-sensitive and pH-resistant linkers. We tested DOX nanoconjugates' cytotoxicity, cellular and nuclear uptake in oral squamous cell carcinoma cell line. Furthermore, we evaluated the therapeutic effect of pH-sensitive and pH-resistant DOX bioconjugates in hamster buccal pouch carcinoma model. Our data indicate that pH-resistant and pH-sensitive DOX-nanoconjugates were equally localized in cancer cells, but the pH-resistant DOX nanoparticles were more localized in the nuclei inducing a 2-fold increase in the apoptotic effect compared with the pH-sensitive DOX nanoparticles. Our in vivo results show significantly higher tumor shrinkage and survival rates in animals treated with DOX pH-resistant AuNPs compared with pH-sensitive ones. Our findings suggest that AuNPs enhance the cytotoxic effect against cancer cells in addition to acting as drug carriers. DOX pH-resistant AuNPs enhanced accumulation of AuNPs in cancer cells' nuclei inducing a significant cellular apoptosis which was confirmed using in vitro and in vivo experiments without deleterious effects on blood cell count.

Gold Nanoparticles Induce Oxidative Stress and Apoptosis in Human Kidney Cells.

Gold nanoparticles (AuNPs) are highly attractive for biomedical applications. Therefore, several in vitro and in vivo studies have addressed their safety evaluation. Nevertheless, there is a lack of knowledge regarding their potential detrimental effect on human kidney. To evaluate this effect, AuNPs with different sizes (13 nm and 60 nm), shapes (spheres and stars), and coated with 11-mercaptoundecanoic acid (MUA) or with sodium citrate, were synthesized, characterized, and their toxicological effects evaluated 24 h after incubation with a proximal tubular cell line derived from normal human kidney (HK-2). After exposure, viability was assessed by the MTT assay. Changes in lysosomal integrity, mitochondrial membrane potential (ΔΨm), reactive species (ROS/RNS), intracellular glutathione (total GSH), and ATP were also evaluated. Apoptosis was investigated through the evaluation of the activity of caspases 3, 8 and 9. Overall, the tested AuNPs targeted mainly the mitochondria in a concentration-dependent manner. The lysosomal integrity was also affected but to a lower extent. The smaller 13 nm nanospheres (both citrate- and MUA-coated) proved to be the most toxic among all types of AuNPs, increasing ROS production and decreasing mitochondrial membrane potential (p ≤ 0.01). For the MUA-coated 13 nm nanospheres, these effects were associated also to increased levels of total glutathione (p ≤ 0.01) and enhanced ATP production (p ≤ 0.05). Programmed cell death was detected through the activation of both extrinsic and intrinsic pathways (caspase 8 and 9) (p ≤ 0.05). We found that the larger 60 nm AuNPs, both nanospheres and nanostars, are apparently less toxic than their smaller counter parts. Considering the results herein presented, it should be taken into consideration that even if renal clearance of the AuNPs is desirable, since it would prevent accumulation and detrimental effects in other organs, a possible intracellular accumulation of AuNPs in kidneys can induce cell damage and later compromise kidney function.

Sculpting Artificial Edges in Monolayer MoS2 for Controlled Formation of Surface-Enhanced Raman Hotspots.

Hotspot engineering has the potential to transform the field of surface-enhanced Raman spectroscopy (SERS) by enabling ultrasensitive and reproducible detection of analytes. However, the ability to controllably generate SERS hotspots, with desired location and geometry, over large-area substrates, has remained elusive. In this study, we sculpt artificial edges in monolayer molybdenum disulfide (MoS2) by low-power focused laser-cutting. We find that when gold nanoparticles (AuNPs) are deposited on MoS2 by drop-casting, the AuNPs tend to accumulate predominantly along the artificial edges. First-principles density functional theory (DFT) calculations indicate strong binding of AuNPs with the artificial edges due to dangling bonds that are ubiquitous on the unpassivated (laser-cut) edges. The dense accumulation of AuNPs along the artificial edges intensifies plasmonic effects in these regions, creating hotspots exclusively along the artificial edges. DFT further indicates that adsorption of AuNPs along the artificial edges prompts a transition from semiconducting to metallic behavior, which can further intensify the plasmonic effect along the artificial edges. These effects are observed exclusively for the sculpted (i.e., cut) edges and not observed for the MoS2 surface (away from the cut edges) or along the natural (passivated) edges of the MoS2 sheet. To demonstrate the practical utility of this concept, we use our substrate to detect Rhodamine B (RhB) with a large SERS enhancement (∼104) at the hotspots for RhB concentrations as low as ∼10-10 M. The single-step laser-etching process reported here can be used to controllably generate arrays of SERS hotspots. As such, this concept offers several advantages over previously reported SERS substrates that rely on electrochemical deposition, e-beam lithography, nanoimprinting, or photolithography. Whereas we have focused our study on MoS2, this concept could, in principle, be extended to a variety of 2D material platforms.

Endocytosis mechanism in physiologically-based pharmacokinetic modeling of nanoparticles

BackgroundThe physiologically based pharmacokinetic (PBPK) model is a useful tool to predict the pharmacokinetics of various types of nanoparticles (NPs). The endocytosis mechanism plays a key role in pharmacokinetics of NPs. However, the effect of endocytosis mechanism both in the blood and tissue are seldom considered in PBPK model. ObjectivesTo investigate the biodistribution of intravenously injected pegylated AuNPs in mice and human using PBPK model considering the endocytosis mechanism both in the blood and tissue. MethodsTaking polyethylene glycol-coated gold nanoparticles (AuNPs) as an example, we developed a PBPK model to explore biodistribution of different size AuNPs. In the model, we considered the role of endocytosis mechanism both in the blood and tissue. In addition, the size-dependent permeability coefficient, excretion rate constant, phagocytic capacity, uptake rate, and release rate were derived from literatures. The mice PBPK model was extrapolated to the human by changing physiology parameters and the number of phagocytic cell (PCs). ResultsAuNPs were primarily distributed in the blood, liver, and spleen regardless of particle size, and almost all captured by the PCs in the liver and spleen, while few was captured in the blood. There are more organ distribution and longer circulation for smaller NPs. The 24-h accumulation of AuNPs decreased with increasing size in the most organ, while the accumulation of AuNPs showed an inverted U-shaped curve in the liver and slight U-shaped curve in the blood. The human results of model-predicted displayed a similar tendency with those in mice. Size, partition coefficients, and body weight were the key factors influencing the organ distribution of AuNPs. ConclusionsThe size played an important role on the distribution and accumulation of AuNPs in various tissues. Our PBPK model was well predicted the NPs distribution in mice and human. A better understanding of these mechanisms could provide effective guides for nanomedine delivery.

Size dependent effects of Gold Nanoparticles in ISO-induced Hyperthyroid Rats

In this study, we applied different sizes of gold nanoparticles (Au-NPs) to isoproterenol (ISO)-induced hyperthyroid heart disease rats (HHD rats). Single dose of 5, 40, 100 nm Au-NPs were injected intravenously. Cardiac safety tests were evaluated by cardiac marker enzymes in serum and cardiac accumulation of Au-NPs were measured by ICP-MS. Our results showed that size-dependent cardiac effects of Au-NPs in ISO-induced hyperthyroid rats. 5 nm Au-NPs had some cardiac protective effect but little accumulation in heart, probably due to smaller size Au-NPs can adapt to whole body easily in vivo. Histological analysis and TUNEL staining showed that Au-NPs can induce pathological alterations including cardiac fibrosis, apoptosis in control groups, however they can protect HHD groups from these harmful effects. Furthermore, transmission electron microscopy and western blotting employed on H9C2 cells showed that autophagy presented in Au-NPs treated cells and that Au-NPs can decrease LC3 II turning to LC3 I and decrease APG7 and caspase 12 in the process in HHD groups, while opposite effects on control groups were presented, which could be an adaptive inflammation reacts. As there are few animal studies about using nanoparticles in the treatment of heart disease, our in vivo and in vitro studies would provide valuable information before they can be considered for clinical use in general.

A gold nanoparticle-based lateral flow biosensor for sensitive visual detection of the potato late blight pathogen, Phytophthora infestans

Phytophthora infestans, the causal agent of late blight in potatoes and tomatoes, is the most important and ongoing pathogenic threat to agricultural production worldwide. Rapid and early identification of P. infestans is an essential prerequisite for countering the further spread of infection. In this study, a novel method for visual detection of P. infestans has been developed by integrating universal primer mediated asymmetric PCR with gold nanoparticle (AuNP)-based lateral flow biosensor. We employed asymmetric PCR to generate large amounts of single-stranded DNA (ssDNA) by amplifying a region of P. infestans-specific repetitive DNA sequence. The ssDNA products were then applied to the lateral flow biosensor to perform a visual detection using sandwich-type hybridization assays. In the presence of target DNA, sandwich-type hybridization reactions among the AuNP–probe, target DNA and capture probe were performed on the test line of the biosensor, and then a characteristic red band was produced for the accumulation of AuNPs. Quantitative analysis obtained by recording the optical intensity of the red band demonstrated that this biosensor could detect as little as 0.1 pg μL−1 genomic DNA. Furthermore, the specificity of the biosensor was confirmed by detecting three other Phytophthora species and two pathogenic fungi. We believe this method has potential application in early prediction of potato late blight disease and instigation of management actions to reduce the risk of epidemic development.

Intracellular accumulation of gold nanoparticles by multipotent bone marrow-derived mesenchymal stem cells

Gold nanoparticles formed by mesenchymal stem cells have tremendous diagnostic and therapeutic potential in cancer. Bone marrow-derived mesenchymal stem cells (BM-MSCs) grown to ∼90% confluency exhibited intracellular gold nanoparticles (AuNPs) accumulation when incubated in 1 mM auric chloride in phosphate buffered saline (PBS) at pH 7.4 for 28 days. Scanning electron microscopy (SEM) and elemental mapping confirmed the growth and distribution of AuNPs within cells and on cell membranes, respectively. Transmission electron microscopy (TEM) of ultrathin-microtome sections of BM-MSCs incubated in auric chloride solution showed the accumulation of AuNPs throughout cells, especially on cell membranes, and within cytoplasm (especially vesicles) and nuclei. Raman spectroscopy showed the interaction of accumulated AuNPs with intracellular proteins, fatty acids, and nucleic acids, and results suggested that these AuNPs could, by enhancing Raman signals, be used to monitor cellular process. The results obtained demonstrated for the first time, the ability of BM-MSCs to bioreduce Au(III) and produce biocompatible AuNPs in cytoplasm and nuclei. This synthesis of gold nanoparticles in BM-MSCs, as intracellular accumulations, without using any added reducing or capping/stabilizing agent is potentially useful for several nano(bio)technological and biomedical applications.

Dielectric properties of AuNPs/PEGMEA/PEGDA nanocomposite film prepared with an α−amino ketone by in-situ photochemical method

Dielectric properties and AC conductivity of in-situ formed AuNPs/PEGMEA/PEGDA nanocomposite film was investigated at room temperature. Frequency dependent dielectric constant shows that there are two main relaxation mechanisms for both samples. First of these mechanisms which correspond to dipolar polarization of long polymer chain was observed at frequencies between 0.1 – 103 Hz, 0.1–104 Hz for PEGMEA/PEGDA film and AuNPs/PEGMEA/PEGDA nanocomposite film, respectively. This mechanism has dielectric constant of 10.8, 14.1 for PEGMEA/PEGDA film and AuNPs/PEGMEA/PEGDA nanocomposite film, respectively. The second mechanism which was attributed to dipolar polarization of chain branches was observed at frequencies between 102 – 106 Hz, 105–107 Hz for PEGMEA/PEGDA film and AuNPs/PEGMEA/PEGDA nanocomposite film, respectively. This mechanism has dielectric constant of 9.6 for PEGMEA/PEGDA film and 10.3 for AuNps/PEGMEA/PEGDA nanocomposite film which cured in the presence of Irg-907 as Type I initiator by using medium pressure mercury light. These relaxation mechanisms can also be detected at frequency dependence of dielectric dissipation (tan δ) as Cole-Cole fitted relaxation peaks and of AC conductivity graphs as frequency independent (DC-like), and frequency dependent regions. DC-like region, it was thought that the main effect of AuNPs was observed, has values for AuNPs/PEGMEA/PEGDA nanocomposite film and PEGMEA/PEGDA film as 6 × 10−7 and 2 × 10−8 S/cm, respectively. In addition to these two polarization mechanisms, electrode polarization was observed at frequencies lower than 1 Hz for AuNps/PEGMEA/PEGDA nanocomposite film due to accumulation of AuNPs.

A lateral flow assay for the determination of human tetanus antibody in whole blood by using gold nanoparticle labeled tetanus antigen.

The authors describe a lateral flow assay (LFA) for the antibody against the infectious bacterium Clostridium tetani. Gold nanoparticles (AuNPs) were linked to tetanus antigen and are captured in the test line via the formation of a sandwich structure composed of AuNP-labeled tetanus antigen, tetanus antibody, and tetanus antigen. This leads to the formation of a characteristic red line due to the accumulation of AuNPs. The formation of the color line allows for a highly sensitive and selective detection of tetanus antibody, both with bare eyes and by smartphone-based quantitative analysis. This assay offers a wide detection range from 0 to 0.5IU·mL-1 and has a linear relationship from 0.01 to 0.1IU·mL-1 with an experimental detection limit of 0.01IU·mL-1. This assay is simple, fast, inexpensive and highly selective. When applied to the detection of tetanus antibody in spiked whole blood, it provided reliable results that compared well to those obtained with a commercial ELISA kit. Graphical abstract ᅟ.

Junction opener protein increases nanoparticle accumulation in solid tumors

Carcinomas contain tight junctions that can limit the penetration and therefore therapeutic efficacy of anticancer agents, especially those delivered by nano-carrier systems. The junction opener (JO) protein is a virus-derived protein that can transiently open intercellular junctions in epithelial tumors by cleaving the junction protein desmoglein-2 (DSG2). Co-administration of JO was previously shown to significantly increase the efficacy of various monoclonal antibodies and chemotherapy drugs in murine tumor models by allowing for increased intratumoral penetration of the drugs. To investigate the size-dependent effect of JO on nanocarriers, we used PEGylated gold nanoparticles (AuNPs) of two different sizes as model drugs and investigated their biodistribution following JO protein treatment. By inductively coupled plasma mass spectrometry (ICP-MS), JO was found to significantly increase bulk tumor accumulation of AuNPs of 35nm but not 120nm particles in both medium (200–300mm3) and large (500–600mm3) tumors. Image analysis of tumor sections corroborates this JO-mediated increase in tumor accumulation of AuNPs. Quantitative intratumoral distribution analyses show that most nanoparticles were found within 100μm of the vasculature, and that the penetration profiles of AuNPs are not significantly affected by JO treatment at the 6h timepoint.

Single gold nanoparticle plasmonic spectroscopy for study of chemical-dependent efflux function of single ABC transporters of single live Bacillus subtilis cells.

ATP-binding cassette (ABC) membrane transporters serve as self-defense transport apparatus in many living organisms and they can selectively extrude a wide variety of substrates, leading to multidrug resistance (MDR). The detailed molecular mechanisms remain elusive. Single nanoparticle plasmonic spectroscopy highly depends upon their sizes, shapes, chemical and surface properties. In our previous studies, we have used the size-dependent plasmonic spectra of single silver nanoparticles (Ag NPs) to study the real-time efflux kinetics of the ABC (BmrA) transporter and MexAB-OprM transporter in single live cells (Gram-positive and Gram-negative bacterium), respectively. In this study, we prepared and used purified, biocompatible and stable (non-aggregated) gold nanoparticles (Au NPs) (12.4 ± 0.9 nm) to study the efflux kinetics of single BmrA membrane transporters of single live Bacillus subtillis cells, aiming to probe chemical dependent efflux functions of BmrA transporters and their potential chemical sensing capability. Similar to those observed using Ag NPs, accumulation of the intracellular Au NPs in single live cells (WT and ΔBmrA) highly depends upon the cellular expression of BmrA and the NP concentration (0.7 and 1.4 nM). The lower accumulation of intracellular Au NPs in WT (normal expression of BmrA) than ΔBmrA (deletion of bmrA) indicates that BmrA extrudes the Au NPs out of the WT cells. The accumulation of Au NPs in the cells increases with NP concentration, suggesting that the Au NPs most likely passively diffuse into the cells, similar to antibiotics. The result demonstrates that such small Au NPs can serve as imaging probes to study the efflux function of the BmrA membrane transporter in single live cells. Furthermore, the dependence of the accumulation rate of intracellular Au NPs in single live cells upon the expression of BmrA and the concentration of the NPs is about twice higher than that of the same sized Ag NPs. This interesting finding suggests the chemical-dependent efflux kinetics of BmrA and that BmrA could distinguish nearly identical sized Au NPs from Ag NPs and might possess chemical sensing machinery.

Nucleic Acid Biosensor Synthesis of an All-in-One Universal Blocking Linker Recombinase Polymerase Amplification with a Peptide Nucleic Acid-Based Lateral Flow Device for Ultrasensitive Detection of Food Pathogens.

In this study, a whole-course nucleic-acid-constructed biosensor that combines the all-in-one concepts of the universal blocking linker recombinase polymerase amplification (UBLRPA) and a peptide nucleic acid (PNA)-based lateral flow device (PLFD) has been developed for the ultrasensitive detection of food pathogens. Using the preamplification UBLRPA principle, a universal linker and C3 space blocker were utilized to produce the universal linker single-duplex DNA products. The developed amplification system was employed to convert duplex products to a single strand. In the signal recognition strategy, a special PNA probe was successfully employed in the portable PLFD. The UBLRPA products were identified visually using the PLFD through dual hybridization (a PNA probe on the gold nanoparticle (Au-NP) was combined with a universal linker on the end of the products; a PNA capture probe was used on the test line and a universal linker on the other end of the products). The accumulation of Au-NPs produced a characteristic red band, enabling the visual detection of a food pathogen without further testing. To demonstrate the value of the all-in-one biosensor, Salmonella enterica subsp. enterica serovar typhimurium was used as a model organism. The biosensor showed high selectivity and extraordinary repeatability using S. typhimurium, and the limit of detection was 4 CFU mL-1. Furthermore, when milk samples artificially contaminated with S. typhimurium were analyzed, the analysis was completed within 30 min without complicated instrumentation. The results exhibited good precision and recovery. This portable all-in-one biosensor demonstrates great promise for the screening of pathogens in food and environmental samples.