Luminescent gelatin nanospheres by encapsulating CdSe quantum dots

Quantum dots (QDs) have been encapsulated within gelatin nanoparticles (GNPs), which gives GNPs fluorescent properties and improves the biocompatibility of QDs. Hydrophilic CdSe QDs were produced through thermodecomposition following the ligand‐exchange method, and were then encapsulated in GNPs. The results of high‐resolution transmission electron microscopy and transmission electron microscopy show that CdSe QDs and QDs‐encapsulated GNPs (QDs‐GNPs) have average diameters of 5 ± 1 and 150 ± 10 nm, respectively. Results of both high‐resolution transmission electron microscopy and confocal laser scanning microscopy indicate that CdSe QDs are successfully encapsulated within GNPs. The QDs‐GNPs have distinctive fluorescent properties with maximum emission at 654 nm, with a 24 nm red‐shift comapred with hydrophilic mercaptoundecanoic acid (MUA)‐modified QDs. In addition, an in vitro cytotoxicity test shows that QDs‐GNPs do not have any toxic effect on cells. It is expected that QDs‐GNPs might be an excellent candidate as a contrast agent in bio‐imaging. Copyright © 2013 John Wiley & Sons, Ltd.     

Cellular Uptake of Gold Nanoparticles and Their Behavior as Labels for Localization Microscopy

Gold nanoparticles (GNPs) enhance the damaging absorbance effects of high-energy photons in radiation therapy by increasing the emission of Auger-photoelectrons in the nm-μm range. It has been shown that the incorporation of GNPs has a significant effect on radiosensitivity of cells and their dose-dependent clonogenic survival. One major characteristic of GNPs is also their diameter-dependent cellular uptake and retention. In this article, we show by means of an established embodiment of localization microscopy, spectral position determination microscopy (SPDM), that imaging with nanometer resolution and systematic counting of GNPs becomes feasible, because optical absorption and plasmon resonance effects result in optical blinking of GNPs at a size-dependent wavelength. To quantify cellular uptake and retention or release, SPDM with GNPs that have diameters of 10 and 25 nm was performed after 2 h and after 18 h. The uptake of the GNPs in HeLa cells was either achieved via incubation or transfection via DNA labeling. On average, the uptake by incubation after 2 h was approximately double for 10 nm GNPs as compared to 25 nm GNPs. In contrast, the uptake of 25 nm GNPs by transfection was approximately four times higher after 2 h. The spectral characteristics of the fluorescence of the GNPs seem to be environment-dependent. In contrast to fluorescent dyes that show blinking characteristics due to reversible photobleaching, the blinking of GNPs seems to be stable for long periods of time, and this facilitates their use as an appropriate dye analog for SPDM imaging.     

Label-free and homogeneous DNA hybridization detection using gold nanoparticles-based chemiluiminescence system

We find that the catalytic activity of gold nanoparticles (GNPs) on luminol-H₂O₂ chemiluminescence (CL) system is greatly enhanced after it is aggregated by 0.5 M NaCl. We use this observation to design a CL detection of DNA hybridization. It is based on that the single- and double-stranded oligonucleotides have different propensities to adsorb on GNPs in colloidal solution, and the hybridization occurred between the probe DNA and target DNA can result in aggregation of the GNPs, producing strong CL emission. In the assay, no covalent functionalization of the GNPs, the probe, or the target DNA is required. The assay, including hybridization and detection, occurs in homogenous solution. The detection limit of target DNA (3σ) was estimated to be as low as 1.1 fM. The sensitivity was increased more than 6 orders of magnitude over that of GNPs-based colorimetric method. The present CL method for DNA hybridization detection offers the advantages of being simple, cheap, rapid and sensitive.     

A gold nanoparticle-mediated enzyme bioreactor for inhibitor screening by capillary electrophoresis

A facile protocol to prepare highly effective and durable in-line enzyme bioreactors inside capillary electrophoresis (CE) columns was developed. To demonstrate the methodology, l-glutamic dehydrogenase (GLDH) was selected as the model enzyme. GLDH was first immobilized onto 38-nm-diameter gold nanoparticles (GNPs), and the functionalized GNPs were then assembled on the inner wall at the inlet end of the CE capillary treated with polyethyleneimine (PEI), producing an in-line GLDH bioreactor. Compared with a GLDH bioreactor prepared by immobilizing GLDH directly on PEI-treated capillary, the GNP-mediated bioreactor showed a higher enzymatic activity and a much better stability. The in-capillary enzyme bioreactor was proven to be very useful for screening of GLDH inhibitors deploying the GLDH-catalyzed α-ketoglutaric acid reaction. The screening assay was preliminarily validated by using a known GLDH inhibitor, namely perphenazine. A Z′ factor value of 0.95 (n = 10) was obtained, indicating that the screening results were highly reliable. Screening of GLDH inhibitors present in medicinal plant extracts by the proposed method was demonstrated. The inhibition percentages were found to be 53% for Radix scutellariae, 45% for Radix codonopsis, 37% for Radix paeoniae alba, and 0% for the other 22 extracts tested at a concentration of 0.6 mg extract/ml.     

Activated Notch2 signaling inhibits differentiation of cerebellar granule neuron precursors by maintaining proliferation.

In the developing cerebellar cortex, granule neuron precursors (GNPs) proliferate and commence differentiation in a superficial zone, the external granule layer (EGL). The molecular basis of the transition from proliferating precursors to immature differentiating neurons remains unknown. Notch signaling is an evolutionarily conserved pathway regulating the differentiation of precursor cells of many lineages. Notch2 is specifically expressed in proliferating GNPs in the EGL. Treatment of GNPs with soluble Notch ligand Jagged1, or overexpression of activated Notch2 or its downstream target HES1, maintains precursor proliferation. The addition of GNP mitogens Jagged1 or Sonic Hedgehog (Shh) upregulates the expression of HES1, suggesting a role for HES1 in maintaining precursor proliferation.     

Biogenic synthesis of <Emphasis Type="Italic">Marsilea quadrifolia</Emphasis> gold nanoparticles: a study of improved glucose utilization efficiency on 3T3-L1 adipocytes

This study aims mainly to provide an insight and understanding of the effect of glucose utilization efficiency of biogenic gold nanoparticles (GNPs) synthesized through the mediation of Marsilea quadrifolia (M. quadrifolia) methanol extract on 3T3-L1 adipocytes. The biosynthesized GNPs were characterized by UV visible spectrophotometry and FTIR. Simultaneously, the nature, stability, and morphological characteristics were analyzed by XRD, TG-DTA, SEM-EDS, HRTEM, and SAED. The results of characterization studies were used to assess the properties of GNPs. The in vitro cytotoxicity screening indicates that 100 μM of biogenic GNPs were displayed 71.23 ± 1.56% of cellular viability in 3T3-L1 adipocyte cells. Subsequently, increased glucose utilization of biosynthesized GNPs based on a dose-dependent manner on 3T3-L1 has also been demonstrated. The effect of GNPs (30 μg) on glucose uptake was higher than that of insulin and metformin. Moreover, the observed results clearly highlight that the biogenic GNPs have higher efficiency of glucose utilization and cellular viability in 3T3-L1 adipocytes with lower toxicity.     

Intercomparison of dose enhancement ratio and secondary electron spectra for gold nanoparticles irradiated by X-rays calculated using multiple Monte Carlo simulation codes

PurposeTargeted radiation therapy has seen an increased interest in the past decade. In vitro and in vivo experiments showed enhanced radiation doses due to gold nanoparticles (GNPs) to tumors in mice and demonstrated a high potential for clinical application. However, finding a functionalized molecular formulation for actively targeting GNPs in tumor cells is challenging. Furthermore, the enhanced energy deposition by secondary electrons around GNPs, particularly by short-ranged Auger electrons is difficult to measure. Computational models, such as Monte Carlo (MC) radiation transport codes, have been used to estimate the physical quantities and effects of GNPs. However, as these codes differ from one to another, the reliability of physical and dosimetric quantities needs to be established at cellular and molecular levels, so that the subsequent biological effects can be assessed quantitatively.MethodsIn this work, irradiation of single GNPs of 50 nm and 100 nm diameter by X-ray spectra generated by 50 and 100 peak kilovoltages was simulated for a defined geometry setup, by applying multiple MC codes in the EURADOS framework.ResultsThe mean dose enhancement ratio of the first 10 nm-thick water shell around a 100 nm GNP ranges from 400 for 100 kVp X-rays to 600 for 50 kVp X-rays with large uncertainty factors up to 2.3.ConclusionsIt is concluded that the absolute dose enhancement effects have large uncertainties and need an inter-code intercomparison for a high quality assurance; relative properties may be a better measure until more experimental data is available to constrain the models.     

Bio-Synthesis of Gold Nanoparticles by <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> and Assessment of Their Conjugation Possibility with Two Types of β-Lactam Antibiotics without Any Additional Linkers

In the present study, biosynthesis of gold nanoparticles (GNPs) by Fusarium oxysporum was carried out and their conjugation possibility with two β-lactam antibiotics was evaluated. F. oxysporum was cultured and the fungal culture supernatant was subjected to the 1 mmol final concentration of chloroauric acid solution. The produced GNPs were analyzed using visible spectrophotometer, X-ray diffraction analysis (XRD) and transmission electron microscope (TEM). After the purification of GNPs, they were subjected to penicillin G and ceftriaxone without any additional linkers. Finally, the mixture was analyzed using visible spectrophotometer, Fourier transform infrared spectroscopy (FTIR) and TEM and subjected to antibacterial activity test using the well diffusion method. Results confirmed the presence of GNPs in the F. oxysporum culture supernatant after the addition of chloroauric acid. TEM results showed that GNPs were spherical and amorphous with sizes around 10–25 nm and XRD confirmed the presence of GNPs in the fungal culture supernatant. After the incubation of GNPs with the antibiotics, FTIR results demonstrated the successful linking of GNPs with the corresponded antibiotics and TEM images showed that GNPs sizes were bigger than the pure ones (around 50–100 nm). Finally the antibacterial activity test indicated that absolutely, the antibacterial properties of the GNPs-β-lactam antibiotics was lowered or not changed in contrast to the pure antibiotics. The present study showed that GNPs had high tendency of conjugation with antibiotics but unlike the previous researches, linking of the antibiotics to GNPs always cannot improve their antibacterial activity based on the antibiotics that were used. The high conjugation affinity of GNPs made them a good candidate as detoxification agent in diverse areas of medicine or environmental sciences.     

Ginger (Zingiber Officinale)-derived nanoparticles in Schistosoma mansoni infected mice: Hepatoprotective and enhancer of etiological treatment

BackgroundNanotechnology has been manufactured from medicinal plants to develop safe, and effective antischistosmal alternatives to replace today’s therapies. The aim of the study is to evaluate the prophylactic effect of ginger-derived nanoparticles (GNPs), and the therapeutic effect of ginger aqueous extract, and GNPs on Schistosoma mansoni (S. mansoni) infected mice compared to praziquantel (PZQ), and mefloquine (MFQ).Methodology/principal findingsEighty four mice, divided into nine different groups, were sacrificed at 6^th, 8^th, and 10^th week post-infection (PI), with assessment of parasitological, histopathological, and oxidative stress parameters, and scanning the worms by electron microscope. As a prophylactic drug, GNPs showed slight reduction in worm burden, egg density, and granuloma size and number. As a therapeutic drug, GNPs significantly reduced worm burden (59.9%), tissue egg load (64.9%), granuloma size, and number at 10^th week PI, and altered adult worm tegumental architecture, added to antioxidant effect. Interestingly, combination of GNPs with PZQ or MFQ gave almost similar or sometimes better curative effects as obtained with each drug separately. The highest therapeutic effect was obtained when ½ dose GNPs combined with ½ dose MFQ which achieved 100% reduction in both the total worm burden, and ova tissue density as early as the 6^th week PI, with absence of detected eggs or tissue granuloma, and preservation of liver architecture.Conclusions/significanceGNPs have a schistosomicidal, antioxidant, and hepatoprotective role. GNPs have a strong synergistic effect when combined with etiological treatments (PZQ or MFQ), and significantly reduced therapeutic doses by 50%, which may mitigate side effects and resistance to etiological drugs, a hypothesis requiring further research. We recommend extending this study to humans.     

An in-silico method to predict and quantify the effect of gold nanoparticles in X-ray imaging

PurposeOver the last few years studies are conducted, highlighting the feasibility of Gold Nanoparticles (GNPs) to be used in clinical CT imaging and as an efficient contrast agent for cancer research. After ensuring that GNPs formulations are appropriate for in vivo or clinical use, the next step is to determine the parameters for an X-ray system’s optimal contrast for applications and to extract quantitative information. There is currently a gap and need to exploit new X-ray imaging protocols and processing algorithms, through specific models avoiding trial-and-error procedures and provide an imaging prognosis tool. Such a model can be used to confirm the accumulation of GNPs in target organs before radiotherapy treatments with a system easily available in hospitals, as low energy X-rays.MethodsIn this study a complete, easy-to-use, simulation platform is designed and built, where simple parameters, as the X-ray’s specifications and experimentally defined biodistributions of specific GNPs are imported. The induced contrast and images can be exported, and accurate quantification can be performed. This platform is based on the GATE Monte Carlo simulation toolkit, based on the GEANT4 toolkit and the MOBY phantom, a realistic 4D digital mouse.ResultsWe have validated this simulation platform to predict the contrast induction and minimum detectable concentration of GNPs on any given X-ray system. The study was applied to preclinical studies but is also expandable to clinical studies.ConclusionsAccording to our knowledge, no other such validated simulation model currently exists, and this model could help radiology imaging with GNPs to be truly deployed.     

A sensitive assay of mercury using fluorescence correlation spectroscopy of gold nanoparticles

We described a new and sensitive method for the determination of mercury ions (Hg²⁺) on the basis of fluorescence correlation spectroscopy (FCS) and recognition of oligonucleotides. In this assay, 30‐nm gold nanoparticles (GNPs) were modified with oligonucleotides containing thymine bases (T) as fluorescent probes, and the principle of this assay was based on the specific binding of Hg²⁺ by two DNA thymine bases. When two GNPs labelled with different oligonucleotides were mixed with a sample containing Hg²⁺, the T‐Hg²⁺‐T binding reaction should cause GNPs to form dimers (or oligomers), which would lead to a significant increase in the characteristic diffusion time of GNPs in the detection volume. The FCS method is a single molecule detection method and can sensitively detect the change in the characteristic diffusion time of GNPs before and after binding reactions. The quantitative analysis was performed according to the relation between the change in the characteristic diffusion time of GNPs and the concentration of Hg²⁺. Under optimal conditions, the linear range of this method was from 0.3 nM to 100 nM, and the detection limit was 0.14 nM for Hg²⁺. This new method was successfully applied for direct determination of Hg²⁺ levels in water and cosmetics samples. Copyright © 2014 John Wiley & Sons, Ltd.     

The gold nanoparticle size and exposure duration effect on the liver and kidney function of rats: In vivo

Nanoparticles (NPs) offer a great possibility for biomedical application, not only to deliver pharmaceutics, but also to be used as novel diagnostic and therapeutic approaches. Currently, there are no data available regarding to what extent the degree of the toxicity and the accumulation of gold nanoparticles (GNPs) are present in in vivo administration. This study aimed to address the GNP size and exposure duration effect on the liver and kidney function of rats: in vivo.MethodsA total of 30 healthy male Wistar-Kyoto rats of the same age (12 weeks old) and weighing 220–240 g of King Saud University colony were used. Animals were randomly divided into groups, two GNP-treated rat groups and one control group (CG). The 50 μl of 10 and 50 nm GNPs was intraperitoneally administered in rats for exposure duration of 3 days. Then, several biochemical parameters such as aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alanine transaminase (ALT), alkaline phosphatase (ALP), urea (UREA) and creatinine (CREA) were evaluated.ResultsIn this study, the AST values increased with the administration of 10 and 50 nm GNPs compared with the control. The AST values significantly increased with 10 nm GNPs compared with 50 nm GNPs and control. The GGT and ALT values decreased with the administration of 10 and 50 nm GNPs compared with the control. The GGT and ALT values significantly decreased with 50 nm GNPs compared with 10 nm GNPs and control. The ALP values significantly decreased with the administration of 10 and 50 nm GNPs compared with the control. The decrease in ALP values with 10 nm GNPs was higher than those compared with 50 nm GNPs. In this study, the levels of UREA and CREA values increased in a non significant manner after the administration of 10 and 50 nm GNPs compared with the control.ConclusionsThis study demonstrates that the increase in the enzymes AST and the decrease in ALP are smaller GNPs (10 nm) size-dependent for exposure duration of 3 days; while the decrease in the enzymes GGT and ALT are bigger GNPs (50 nm) size-dependent. The levels of UREA and CREA values indicated no significant changes with the administration of 10 and 50 nm GNPs for exposure duration of 3 days compared with the control. The administration of 10 and 50 nm GNPs for short exposure duration of 3 days induced only significant variations with some liver enzymes while kidney showed no significant variations. This study suggests that synthesis and metabolism of GNPs as well as the protection of the liver will be more important issues for medical applications of gold-based nanomaterials in future.     

Gold nanoparticles based dipstick immunoassay for the rapid detection of dichlorodiphenyltrichloroethane: An organochlorine pesticide

Gold nanoparticles (GNPs) based dipstick competitive immunoassay was developed to detect organochlorine pesticide such as DDT at nanogram level (ppb). GNPs of definite size were synthesized and conjugated to anti-DDT antibodies (IgY), which served as the detecting reagent. DDA-BSA conjugate (antigen) was immobilized on to nitro cellulose (NC) membrane containing strip. GNPs conjugated anti-DDT antibodies were treated with different concentrations of free DDT ranging from 0.7 ng mL⁻¹ to 1000 ng mL⁻¹ to form an immunocomplex. This immunocomplex solution was further reacted with DDA-BSA conjugate immobilized NC membrane containing strips by dipping the strip in the immunocomplex solution. The free GNPs conjugated anti-DDT antibodies present in the immunocomplex solution were targeted for competitive binding with immobilized DDA-BSA on NC membrane containing strip. Depending on the concentration of free DDT in the sample the binding of GNPs conjugated anti-DDT antibodies to the immobilized DDA-BSA varied and was detected by the development of red color (due to gold nanoparticles) in the detection zone of NC membrane containing strips. The intensity of color development was inversely proportional to the DDT concentration with maximum intensity at zero DDT concentration. The lowest detection limit of DDT was determined to be 27 ng mL⁻¹ with the optimized conditions. The dipstick technique based on GNPs is suitable for the detection of several toxins in food and environmental samples and can be applied for rapid on-site testing of pesticides.     

Improved efficiency and stability of secnidazole – An ideal delivery system

Secnidazole (α,2-Dimethyl-5-nitro-1H-imidazole-1-ethanol) is a highly effective drug against a variety of G⁺/G⁻ bacteria but with significant side effects because it is being used in very high concentration. In this study, gold nanoparticles (GNP_S) were selected as a vehicle to deliver secnidazole drug at the specific site with more accuracy which made the drug highly effective at substantially low concentrations. The as-synthesized GNPs were capped with Human Serum Albumin (HSA) and subsequently bioconjugated with secnidazole because HSA provides the stability and improves the solubility of the bioconjugated drug, secnidazole. The quantification of covalently bioconjugated secnidazole with HSA encapsulated on enzymatically synthesized GNPs was done with RP-HPLC having SPD-20 A UV/VIS detector by using the C-18 column. The bioconjugation of GNPs with secnidazole was confirmed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The bioconjugated GNPs were characterized by UV–VIS spectroscopy, TEM, Scanning Electron Microscopy (SEM) and DLS. Zeta potential confirmed the stability and uniform distribution of particles in the emulsion of GNPs. The separation of bioconjugated GNPs, unused GNPs and unused drug was done by gel filtration chromatography. The minimal inhibitory concentration of secnidazole-conjugated gold nanoparticles (Au-HSA-Snd) against Klebsiella pneumonia (NCIM No. 2957) and Bacillus cereus (NCIM No. 2156) got improved by 12.2 times and 14.11 times, respectively, in comparison to pure secnidazole. Precisely, the MIC of Au-HSA-Snd against K. pneumonia (NCIM No. 2957) and B. cereus (NCIM No. 2156) were found to be 0.35 and 0.43 μg/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 μg/ml, respectively.     

Biogenic synthesis of gold nanoparticle using fractioned cellular components from eukaryotic algae and cyanobacteria

In the present investigation fractioned cellular components like intact pigment bearing thylakoids/chloroplasts, carotenoids, protein, polysaccharides were extracted from the cyanobacterium Anabaena sphaerica and green alga Chlorococcum infusionum. Each of these extracts was used separately in search for efficient reducing agents during gold nanoparticle (GNP) production in pro‐ and eukaryotic algal cell systems. The whole biomass and extracted compounds or cellular structures were exposed in 25 mg L^?1 aqueous hydrogen tetrachloroaurate solutions separately at room temperature. Isolated viable chloroplasts from C. infusionum and thylakoids from A. sphaerica were found to be able to reduce gold ions. The protein extracts of both strains were also able to synthesize GNP at 4°C. Extracted polysaccharides of the two strains responded differently. Polysaccharides from A. sphaerica showed positive response in GNP synthesis, whereas no change was observed for C. infusionum. The carotenoids extracts from both strains acted like an efficient reducing agent. Initially the reducing efficiency of these extracted components was confirmed by the appearance of purple color in biomass or in experimental media. The GNPs, synthesized within the biomass were extracted by sonication with sodium citrate. The UV–vis spectroscopy of extracted purple colored suspensions and media showed the absorption bands at approximately 530–540 nm indicating a strong positive signal of GNP synthesis. Transmission electro n microscopy determined the size and shapes of the particles. The X‐ray diffraction study of the synthesized GNP revealed that the 2θ values appeared at 38.2°, 44.5°, 64.8° and 77.8°. Amongst all, isolated thylakoids and chloroplast showed only spherical GNP production with variable size range at pH 4. Monodisperse GNPs were also synthesized by isolated thylakoids and chloroplast at pH 9. A detailed morphological change of gold treated biomass was revealed employing scanning electron microscopy. The fluorescent property of gold loaded cells was studied by fluorescence microscopy.     

Bioaccumulation and toxicity of gold nanoparticles after repeated administration in mice

Gold nanoparticles (GNPs) offer a great promise in biomedicine. Currently, there is no data available regarding the accumulation of nanoparticles in vivo after repeated administration. The purpose of the present study was to evaluate the bioaccumulation and toxic effects of different doses (40, 200, and 400 μg/kg/day) of 12.5 nm GNPs upon intraperitoneal administration in mice every day for 8 days.The gold levels in blood did not increase with the dose administered, whereas in all the organs examined there was a proportional increase on gold, indicating efficient tissue uptake. Although brain was the organ containing the lowest quantity of injected GNPs, our data suggest that GNPs are able to cross the blood-brain barrier and accumulate in the neural tissue. Importantly, no evidence of toxicity was observed in any of the diverse studies performed, including survival, behavior, animal weight, organ morphology, blood biochemistry and tissue histology. The results indicate that tissue accumulation pattern of GNPs depend on the doses administered and the accumulation of the particles does not produce sub-acute physiological damage.     

Intracellular uptake,transport, and processing of gold nanostructures

Abstract

The emerging field of nanomedicine requires better understanding of the interface between nanotechnology and medicine. Better knowledge of the nano-bio interface will lead to better tools for diagnostic imaging and therapy. In this review, recent progress in understanding of how size, shape, and surface properties of nanoparticles (NPs) affect intracellular fate of NPs is discussed. Gold nanostructures are used as a model system in this regard since their physical and chemical properties can be easily manipulated. The NP-uptake is dependent on the physiochemical properties, and once in the cell, most of the NPs are trafficked via an endo-lysosomal path followed by a receptor-mediated endocytosis process at the cell membrane. Within the size range of 2–100 nm, Gold nanoparticles (GNPs) of diameter 50 nm demonstrate the highest uptake. Cellular uptake studies of gold nanorods (GNRs) show that there is a decrease in uptake as the aspect ratio of GNRs increases. Theoretical models support the size- and shape-dependent NP-uptake. The intracellular transport of targeted NPs is faster than untargeted NPs. The surface ligand and charge of NPs play a bigger role in their uptake, transport, and organelle distribution. Exocytosis of NPs is dependent on size and shape as well; however, the trend is different compared to endocytosis. GNPs are now being incorporated into polymer and lipid based NPs to build multifunctional devices. A multifunctional platform based on gold nanostructures, with multimodal imaging, targeting, and therapeutics; hold the possibility of promising directions in medical research.