Morphologically Well-defined Gold Nanoparticles Embedded in Thermo-Responsive Hydrogel Matrices

2004 ◽  
Vol 820 ◽  
Author(s):  
Chun Wang ◽  
Nolan T. Flynn ◽  
Robert Langer
Keyword(s):  
Gold Nanoparticles ◽  
Au Nanoparticles ◽  
Nanocomposite Materials ◽  
Thiol Groups ◽  
Surface Charges ◽  
Bulk Properties ◽  
Nanocomposite Hydrogels ◽  
Long Term Stability ◽  
Equilibrium Swelling

AbstractNanocomposite materials consisting of colloidal gold (Au) nanoparticles embedded in thermo-responsive poly(N-isopropylacrylamide) (PNIPAm) hydrogels are synthesized. Thiol groups that bind to both Au3+ ions and colloidal Au are incorporated into the side-chains of the PNIPAm hydrogels through copolymerization. This report describes formation of morphologically well-defined Au nanoparticles with varying long-term stability inside the hydrogel matrices containing adjustable concentrations of thiols. Compared with the non-Au containing PNIPAm hydrogels, the Au-PNIPAm nanocomposite hydrogels have shown higher degrees of equilibrium swelling and different temperature-triggered phase transitions. It is hypothesized that these remarkable changes in hydrogel bulk properties are related to the different morphologies and sizes, and possibly the amount of surface charges, of the Au nanoparticles.

scholarly journals Universal Method for Producing Reduced Graphene Oxide/Gold Nanoparticles Composites with Controlled Density of Grafting and Long-Term Stability

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 602 ◽  
Author(s):  
Szustakiewicz ◽  
Kołsut ◽  
Leniart ◽  
Lewandowski
Keyword(s):  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Hybrid Nanostructures ◽  
Ex Situ ◽  
Universal Method ◽  
Term Stability ◽  
Long Term Stability ◽  
Reduced Graphene

In this study, we report a universal approach allowing the non-covalent deposition of gold nanoparticles on reduced graphene oxide surface in a controlled fashion. We used a modified Hummers method to obtain graphene oxide, which then underwent surficial functionalization with carboxyl moieties coupled with simultaneous reduction. Nanoparticles were synthesized ex-situ and capped with a thiolated poly-ethylene glycol (PEG) ligand. The interactions between the surface of modified graphene oxide and nanoparticle ligands enabled the formation of stable hybrid graphene-nanoparticles materials in the aqueous phase. Using this technique, we were able to cover the surface of graphene with gold nanoparticles of different shapes (spheres, rods, triangles, stars, and bipyramids), broad range of sizes (from 5 nm to 100 nm) and controlled grafting densities. Moreover, materials obtained with this strategy exhibited long-term stability, which coupled with the versatility and facility of preparation, makes our technique appealing in the light of increasing demand for new graphene-based hybrid nanostructures.

scholarly journals The interaction effect of bacterial cellulose with gold nanoparticles obtained by metal-vapor synthesis

2019 ◽  
Vol 488 (4) ◽  
pp. 391-396
Author(s):  
M. S. Rubina ◽  
M. A. Pigaleva ◽  
I. E. Butenko ◽  
A. V. Budnikov ◽  
A. V. Naumkin ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Ir Spectroscopy ◽  
Bacterial Cellulose ◽  
Interaction Effect ◽  
Au Nanoparticles ◽  
Cellulose Nanofibrils ◽  
Composite Films ◽  
Metal Vapor ◽  
Nanocomposite Materials ◽  
Metal Core

In the present work, a promising method was proposed for the formation of new functional nanocomposite materials based on bacterial cellulose and Au nanoparticles obtained by a biocompatible and environmentally friendly metal vapor synthesis. The structure and composition of the composite films surface were studied by XPS, SEM, and IR spectroscopy. It was determined that Au nanoparticles effectively chemisorb the bacterial cellulose nanofibrils forming nanoparticles with a size of about 25 nm with a metal core-hydrocarbon shell structure.

scholarly journals Chemiresistors Based on Bisdithiocarbamate Interlinked Gold Nanoparticles

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 933
Author(s):  
Yelyena Daskal ◽  
Susann Rabe ◽  
Rosemarie Dittrich ◽  
Christiane Oestreich ◽  
Yvonne Joseph
Keyword(s):  
Gold Nanoparticles ◽  
Volatile Organic Compounds ◽  
Gold Nanoparticle ◽  
Organic Compounds ◽  
Sensing Properties ◽  
Term Stability ◽  
Long Term Stability ◽  
Volatile Organic ◽  
Assembly Structure

The assembly, structure, composition and sensing properties of novel bisdithiocarbamate based gold nanoparticle networks have been investigated. The sensing properties have been studied with vapors of toluene, 1-propanol, water, and 4-methyl-2-pentanone. We demonstrated that bisdithiocarbamates based chemiresistive sensors show sensing properties versus volatile organic compounds (VOC) comparable to thiol based composites but that they are superior in their long term stability.

Stability and Change in Emotional Intelligence: Exploring the Transition to Young Adulthood

2005 ◽  
Vol 26 (2) ◽  
pp. 100-106 ◽  
Author(s):  
James D.A. Parker ◽  
Donald H. Saklofske ◽  
Laura M. Wood ◽  
Jennifer M. Eastabrook ◽  
Robyn N. Taylor
Keyword(s):  
High School ◽  
Emotional Intelligence ◽  
Postsecondary Education ◽  
Life Transition ◽  
Full Time ◽  
Major Life ◽  
Long Term Stability ◽  
Time Period ◽  
Transition From High School

Abstract. The concept of emotional intelligence (EI) has attracted growing interest from researchers working in various fields. The present study examined the long-term stability (32 months) of EI-related abilities over the course of a major life transition (the transition from high school to university). During the first week of full-time study, a large group of undergraduates completed the EQ-i:Short; 32 months later a random subset of these students (N = 238), who had started their postsecondary education within 24 months of graduating from high school, completed the measures for a second time. The study found EI scores to be relatively stable over the 32-month time period. EI scores were also found to be significantly higher at Time 2; the overall pattern of change in EI-levels was more than can be attributed to the increased age of the participants.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

The Stability of the WHO Reference Thromboplastin NIBS & C 67/40

1979 ◽  
Vol 42 (04) ◽  
pp. 1135-1140 ◽  
Author(s):  
G I C Ingram
Keyword(s):  
Human Brain ◽  
Collaborative Study ◽  
Calibration Constant ◽  
Long Term Stability ◽  
Freeze Dried ◽  
Show Evidence ◽  
Human Material ◽  
Reference Preparation ◽  
The Stability

SummaryThe International Reference Preparation of human brain thromboplastin coded 67/40 has been thought to show evidence of instability. The evidence is discussed and is not thought to be strong; but it is suggested that it would be wise to replace 67/40 with a new preparation of human brain, both for this reason and because 67/40 is in a form (like Thrombotest) in which few workers seem to use human brain. A �plain� preparation would be more appropriate; and a freeze-dried sample of BCT is recommended as the successor preparation. The opportunity should be taken also to replace the corresponding ox and rabbit preparations. In the collaborative study which would be required it would then be desirable to test in parallel the three old and the three new preparations. The relative sensitivities of the old preparations could be compared with those found in earlier studies to obtain further evidence on the stability of 67/40; if stability were confirmed, the new preparations should be calibrated against it, but if not, the new human material should receive a calibration constant of 1.0 and the new ox and rabbit materials calibrated against that.The types of evidence available for monitoring the long-term stability of a thromboplastin are discussed.

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