Understanding the linear correlation between diffusion coefficient and molecular weight. A model to estimate diffusion coefficients in acetonitrile solutions

Valencia, Drochss P.; González, Felipe J.

doi:10.1016/j.elecom.2010.11.032

Cited by 87 publications

(47 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[11] Cyclic voltammetry analysis of EDOT or EDOT-Dex (Figure2), respectively,s hows that the typical trace crossingo nt he reverse sweep,w hich is attributed to the initial stages of polymer nucleationa nd growth on the electrode surface, is present only in the case of pristine EDOT monomer. [13] As reportedi nF igures S1-2, electrodeposition in multiple scan mode of EDOT enables the progressive formationo fa PEDOTf ilm, as confirmed by the increase of both capacitive and faradaic current upon multiple cycles.O nthe contrary,t he same procedure applied to EDOT-Dex did not provide any evidence of polymer formation.I nf act, the dramatic decrease of the peak current during the second potential sweep (see Figure S1 b) suggestst hat, upon oxidation, EDOT-Dex is likely to decompose at the electrode interface rather than promoting the polymer formation,p resumably due to steric hindrance. [13] As reportedi nF igures S1-2, electrodeposition in multiple scan mode of EDOT enables the progressive formationo fa PEDOTf ilm, as confirmed by the increase of both capacitive and faradaic current upon multiple cycles.O nthe contrary,t he same procedure applied to EDOT-Dex did not provide any evidence of polymer formation.I nf act, the dramatic decrease of the peak current during the second potential sweep (see Figure S1 b) suggestst hat, upon oxidation, EDOT-Dex is likely to decompose at the electrode interface rather than promoting the polymer formation,p resumably due to steric hindrance.…”

supporting

confidence: 53%

Biochemically Controlled Release of Dexamethasone Covalently Bound to PEDOT

Carli

Trapella

Armirotti

et al. 2018

Chemistry A European J

View full text Add to dashboard Cite

PEDOT (Poly(3,4-ethylenedioxythiophene)) is one of the most promising electrode materials for biomedical applications like neural recording and stimulation, thanks to its enhanced biocompatibility and electronic properties. Drug delivery by PEDOT is typically achieved by incorporating drugs as dopants during the electrodeposition procedure and a subsequent release can be promoted by applying a cathodic trigger that reduces PEDOT while enabling the drug to diffuse. This approach has several disadvantages including, for instance, the release of contaminants mainly due to PEDOT decomposition during electrochemical release. Herein we describe a new strategy based on the formation of a chemical linkage between the drug and the conductive polymer. In particular, dexamethasone was successfully integrated into a new electropolymerized PEDOT-Dex composite, leading to a self-adjusting drug release system based on a biochemically hydrolysable bond between dexamethasone and PEDOT.

show abstract

supporting

confidence: 53%

Biochemically Controlled Release of Dexamethasone Covalently Bound to PEDOT

Carli

Trapella

Armirotti

et al. 2018

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Comparing the D values for acetoin and lactic acid with the D values for the majority photolysis products with lower D values, the ratio is found to be in the range of 1.4:1-1.6:1 (D acetoin/lactic acid / D majority product ratio). Doubling the size/mass of the molecule (i.e., either a homodimer or heterodimer of the small molecules) should lower the measured D value by approximately √2 depending on the molecular geometry, suggesting that the majority of the photolysis products are approximately twofold the size of the individual molecules already identified (i.e., acetoin, lactic acid) (41,42). These D values indicate that the major products of photolysis of PA are small oligomers.…”

Section: Resultsmentioning

confidence: 93%

Photochemistry of aqueous pyruvic acid

Griffith

Carpenter

Shoemaker³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

125

289

View full text Add to dashboard Cite

The study of organic chemistry in atmospheric aerosols and cloud formation is of interest in predictions of air quality and climate change. It is now known that aqueous phase chemistry is important in the formation of secondary organic aerosols. Here, the photoreactivity of pyruvic acid (PA; CH 3 COCOOH) is investigated in aqueous environments characteristic of atmospheric aerosols. PA is currently used as a proxy for α-dicarbonyls in atmospheric models and is abundant in both the gas phase and the aqueous phase (atmospheric aerosols, fog, and clouds) in the atmosphere. The photoreactivity of PA in these phases, however, is very different, thus prompting the need for a mechanistic understanding of its reactivity in different environments. Although the decarboxylation of aqueous phase PA through UV excitation has been studied for many years, its mechanism and products remain controversial. In this work, photolysis of aqueous PA is shown to produce acetoin (CH 3 CHOHCOCH 3 ), lactic acid (CH 3 CHOHCOOH), acetic acid (CH 3 COOH), and oligomers, illustrating the progression from a three-carbon molecule to four-carbon and even six-carbon molecules through direct photolysis. These products are detected using vibrational and electronic spectroscopy, NMR, and MS, and a reaction mechanism is presented accounting for all products detected. The relevance of sunlight-initiated PA chemistry in aqueous environments is then discussed in the context of processes occurring on atmospheric aerosols.

show abstract

“…Measurement of molecular diffusion using pulsed field gradient (PFG) NMR is a way to extract the microstructural information (19). Diffusion of large molecules, such as lipids or triglycerides, in adipose tissue is influenced by several factors, including molecular weight, temperature, lipid droplet size, and chemical composition (20)(21)(22)(23)(24). Recently, the diffusion properties of intramyocellular (IMCL) and extramyocellular lipids in the skeletal muscle of rodents (25) and humans (26) have been investigated, and restricted diffusion has been observed in IMCL.…”

Section: Nmr Data Acquisition and Analysismentioning

confidence: 99%

Differentiating brown and white adipose tissues by high-resolution diffusion NMR spectroscopy

Verma

Nagashima

Yaligar

et al. 2017

Journal of Lipid Research

View full text Add to dashboard Cite

majority of body fat, which is utilized for energy storage, whereas BAT is a minor portion that is involved in thermogenesis, due to the presence of uncoupling protein 1 (UCP1) in the mitochondria. In addition to the differences in energy storage and expenditure, BAT is a highly heterogeneous, densely vascularized tissue with abundant oxygen, blood supply, and iron-rich mitochondria (6, 7). WAT is composed of unilocular lipid droplets, whereas BAT is composed of multilocular lipid droplets scattered throughout the cytoplasm and surrounded by mitochondria.Positron emission tomography (PET) has been the gold standard for imaging BAT (8, 9) because of a selective image contrast of activated BAT by the increased uptake of 18 F-deoxyglucose. However, PET is not suitable for longitudinal studies because it requires injection of exogenous radioactive tracers. Magnetic resonance (MR)-based methods are more promising for real-time and long-term observation of fat accumulation and consumption (10). Traditional MR-based approaches exploit the differences in the water content in WAT and BAT using chemical shift imaging or the Dixon technique (11-13). Imaging of water and fat permits quantitative assessment of the fat fraction. Additionally, the differences in iron content, perfusion, and vasculature have been exploited by T 2 and T 2 * relaxation techniques (14, 15). However, although WAT and BAT are manually separable by color and texture, they cannot be easily distinguished by MR because of the similarity in their magnetic and chemical characteristics (14,15).Applications of nontraditional MR methodologies for selectively detecting BAT have been attempted. Branca and Warren (16, 17) have studied focusing on intermolecular multiple-quantum coherences through dipolar Abstract There are two types of fat tissues, white adipose tissue (WAT) and brown adipose tissue (BAT), which essentially perform opposite functions in whole body energy metabolism. There is a large interest in identifying novel biophysical properties of WAT and BAT by a quantitative and easy-to-run technique. In this work, we used high-resolution pulsed field gradient diffusion NMR spectroscopy to study the apparent diffusion coefficient (ADC) of fat molecules in rat BAT and WAT samples. The ADC of fat in BAT and WAT from rats fed with a chow diet was compared with that of rats fed with a high-fat diet to monitor how the diffusion properties change due to obesity-associated parameters such as lipid droplet size, fatty acid chain length, and saturation. Feeding a high-fat diet resulted in increased saturation, increased chain lengths, and reduced ADC of fat in WAT. The ADC of fat was lower in BAT relative to WAT in rats fed both chow and high-fat diets. Diffusion of fat was restricted in BAT due to the presence of small multilocular lipid droplets. Our findings indicate that in vivo diffusion might be a potential way for better delineation of BAT and WAT in both lean and obese states.-Verma, S. K., K. Nagashima, J. Yaligar, N. Michael, S. S. Lee, T. Xianfeng, V...

show abstract

Understanding the linear correlation between diffusion coefficient and molecular weight. A model to estimate diffusion coefficients in acetonitrile solutions

Cited by 87 publications

References 13 publications

Biochemically Controlled Release of Dexamethasone Covalently Bound to PEDOT

Biochemically Controlled Release of Dexamethasone Covalently Bound to PEDOT

Photochemistry of aqueous pyruvic acid

Differentiating brown and white adipose tissues by high-resolution diffusion NMR spectroscopy

Contact Info

Product

Resources

About